JP3328602B2 - Inkjet recording paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material for recording by using an ink comprising a water-soluble dye, and more particularly to an ink jet recording paper capable of obtaining a high-quality recorded image having excellent light fastness.

[0002]

2. Description of the Related Art Ink jet recording is a recording method in which ink droplets are ejected by various methods to form an image. It is easy to achieve high speed and full color printing, the sound during printing is small, and the apparatus is inexpensive. Because it has such features as
In recent years, it has remarkably spread. In particular, recent full-color inkjet printers have realized high resolution and high gradation comparable to silver halide photography as a result of the miniaturization of ink droplets and the improvement of ink significantly, and digital images taken with a digital camera etc. The number of users who directly print with an inkjet printer is also increasing.

[0003] Also, since the recorded image is of high quality,
Similar to silver halide photographs, the number of cases of posting or storage for a long period of time is increasing, and the demand for long-term storability, particularly image light fastness, is also increasing for ink jet recording paper as well as high image quality (high quality) of the image. It is getting. However, since dye ink is used in a general inkjet printer, the recorded image is discolored and the image quality is deteriorated due to the influence of ultraviolet light included in sunlight or irradiation light of a fluorescent lamp. Therefore, in order to improve such problems,
Although measures to use pigment ink etc. may be adopted,
From the viewpoint of the sharpness of color development, it is desired to improve the light resistance of the dye ink system.

As a means for improving the light fastness of an image by a dye ink system, a method of incorporating a benzotriazole compound and a hindered phenol compound in the dye ink (JP-A-9-132742) is disclosed. For example, a method of adding a benzophenone-based or benzotriazole-based ultraviolet absorber (JP-A-57-87988, JP-A-63-222885), and a method of adding a hindered amine-based antioxidant (Japanese Patent Laid-Open No. 61-1987). -14
No. 65913), or a method using a combination of a zinc oxide powder and a cationic resin (Japanese Patent Application Laid-Open No. 7-32725).

However, in any of these cases,
There is a drawback that it is difficult to uniformly disperse the above-mentioned additives, and it has not yet been possible to obtain a sufficient effect on image light fastness, and it cannot be sufficiently satisfied in terms of high image quality. Was. Also, a method of adding a phenolic antioxidant (JP-A-9-1922)
Although these methods have been proposed, these methods have an effect on the light fastness of the image portion, but have the disadvantage that the white light fastness is insufficient, such as yellowing of a blank portion of the ink jet recording paper.

As a method for improving storage stability including water resistance, a method of adding a cationic resin and magnesium sulfate (JP-A-61-43593) or a method of adding a water-soluble salt of a cationic resin and aluminum is used. (Japanese Patent Application Laid-Open No. 61-57379) and the like have been proposed. However, in the case of using a water-soluble salt of aluminum, the image quality is not sufficient, and in the case of using magnesium sulfate, there is a disadvantage that the image quality is small but the light resistance is not sufficient.

[0007]

SUMMARY OF THE INVENTION The present inventors have studied to solve the above-mentioned drawbacks. As a result, when printing was performed on ink-jet paper in which only a water-soluble aluminum salt was blended in the ink-receiving layer, a unit was printed. It has been found that the printing portion where the amount of ink adhered per area is large has metallic luster, and the image quality is degraded. Metallic luster is particularly likely to occur in high-quality (photo-type) inkjet printers that have a relatively large ink ejection volume. Further, when a coloring layer containing colloidal silica as a main component is provided on the ink receiving layer, even if the amount of ink adhered is small, metallic luster occurs, which is a particular problem.

[0008] Although the cause of the metallic luster is not clear, it is considered that one of the causes is that an aluminum ion and a dye form a complex. As a result of further studies by the present inventors,
By simultaneously containing a specific amount of a water-soluble magnesium salt together with a water-soluble aluminum salt in the ink receiving layer,
The inventors have found that the metallic luster of the printed portion can be suppressed, and have reached the present invention. Accordingly, it is an object of the present invention to provide a high-quality inkjet recording paper which is excellent in image light fastness, ink absorption and color development, and has a glossiness, which is recorded using an ink comprising a water-soluble dye. .

[0009]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
What is claimed is: 1. An ink jet recording sheet comprising an ink receiving layer mainly comprising a pigment and a binder on at least one surface of a support, wherein the ink receiving layer is composed of a water-soluble aluminum salt (A) and a water-soluble magnesium salt ( M)
(A) and (M) are achieved by the ink jet recording paper characterized in that the content of each salt in the ink receiving layer satisfies the following relational expression. 3 ≦ a + m ≦ 5 and 1 ≦ a ≦ 2 where a is an aluminum ion equivalent (mmol / 100 g of pigment) and m is a magnesium ion equivalent (mmol / 100 g of pigment).

Here, the aluminum (or magnesium) ion conversion value is a value obtained by converting the relationship between the amount of aluminum (or magnesium) ion to the amount of pigment contained in the ink receiving layer, per 100 g of the pigment. is there. For example, aluminum sulfate (Al
The aluminum ion conversion value a when ₂ (SO ₄ ) ₃ ) is contained in 100 g of pigment per 100 g of pigment is calculated by the following equation. a (mmol / 100 g of pigment) = W × (2 × 1/34)
2.17: Al ₂ (SO ₄ ) ₃ molecular weight) × 1,000 Further, by providing a color-forming layer containing colloidal silica as a main component on the ink receiving layer, an ink jet recording paper having excellent glossiness can be obtained. be able to.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The support in the present invention can be appropriately selected from known sheet-like supports. In the present invention, paper made from wood cellulose is particularly preferable. The above paper is mainly composed of pulp for papermaking. As papermaking pulp, LBPK, N
Examples include, but are not limited to, chemical pulp such as BPK, mechanical pulp such as GP and TMP, and waste paper pulp. These pulp are used alone or in combination as needed. Further, it is also possible to use a so-called laminated paper or the like in which a resin film is bonded to the surface of the paper or processed with a molten resin.

The ink receiving layer according to the present invention is a coating layer having a pigment and a binder as main components and having an ink absorbing ability. Pigments used herein include light and heavy calcium carbonate, kaolin, clay, talc, titanium dioxide, zinc oxide, satin white, magnesium silicate, calcium silicate, aluminum silicate, aluminum hydroxide, alumina, pseudoboehmite, carbonate White pigments such as magnesium, silica, and zeolite are exemplified. In the present invention, these synthetic silicas are preferred, but in particular,
White carbon and anhydrous silica described in Chemistry Handbook, Applied Chemistry (published by Maruzen Co., Ltd. on October 15, 1986, edited by The Chemical Society of Japan) at page 256 are preferred, and white carbon is most preferred.

The type of the binder used in the ink receiving layer is not particularly limited as long as it has a strong adhesive force to paper as a support and forms a film after drying. Examples of such a binder include starches such as oxidized starch, esterified starch, enzyme-modified starch, and cationized starch, various polyvinyl alcohols having different degrees of saponification and derivatives thereof, casein, proteins such as soy protein, carboxymethyl cellulose. And water-dispersible polymer compounds such as acrylic emulsion, vinyl acetate emulsion, vinylidene chloride emulsion, styrene-butadiene latex, acrylonitrile-butadiene latex, and polyester dispersion.

In the ink receiving layer thus constituted, the total of the water-soluble aluminum salt and the water-soluble magnesium salt is 3 mmol / 100 g of pigment / 100 g of pigment / 100 g of pigment in terms of aluminum ion and magnesium ion. The water-soluble aluminum salt is contained in an amount of 1 mmol / 100 g of pigment to 2 mmol / 100 g of pigment in terms of aluminum ion. In particular, the total amount of the water-soluble aluminum salt and the water-soluble magnesium salt was 3.5 mmol / pigment 10 in terms of aluminum ion and magnesium ion.
It is preferable that the amount is in the range of 0 g to 4.5 mmol / 100 g of the pigment, and that the content of the water-soluble aluminum salt is 1.5 mmol / 100 g to 2.0 mmol / 100 g of the pigment in terms of aluminum ion.

If the sum of the water-soluble aluminum salt and the water-soluble magnesium salt, or the amount of the water-soluble aluminum salt is less than the above lower limit, the light resistance is not sufficient. If either of them exceeds the upper limit value, metallic gloss can be seen only in the image portion where the amount of ink adhered is large, so that gloss unevenness occurs in the image and the quality of the entire image deteriorates.

The water-soluble aluminum salt used in the present invention includes, for example, aluminum sulfate, aluminum ammonium sulfate, aluminum potassium sulfate, aluminum sodium sulfate, aluminum nitrate, and aluminum chloride. Among them, aluminum sulfate is preferred. . On the other hand, as the water-soluble magnesium salt, for example, magnesium sulfate, magnesium chloride, magnesium acetate and the like can be mentioned, but magnesium sulfate is particularly preferable.

Further, it is preferable to appropriately add a dye fixing agent, which is a cationic resin, to the ink receiving layer in order to impart image water resistance. As such a dye fixing agent,
For example, dicyandiamide / alkylamine polycondensate,
Dicyandiamide / formalin polycondensate, polyethyleneimine derivative, alkylamine / epichlorohydrin polycondensate, polymethacrylic acid quaternary ammonium salt derivative, polydiallyldimethylammonium chloride, etc.
Commercially available dye fixing agents can be mentioned. Such dye fixing agents can be used alone or in combination of two or more. In the present invention, further, an antifoaming agent, a surface sizing agent, a water-proofing agent, a pH adjuster, an ultraviolet absorber, an antioxidant, a dye or a color pigment for adjusting the hue, a fluorescent dye, etc. It can be appropriately added to the ink receiving layer as long as the effect is not impaired.

In the present invention, the coating amount of the ink receiving layer provided on the support is preferably from 5 to 25 g / m ² , more preferably from 7 to ²⁰ g / m ² , in terms of solid content.
When the ink receiving layer is less than 5 g / m ² , sufficient ink absorbency cannot be obtained and bleeding or the like occurs, and when the ink receiving layer exceeds 25 g / m ² , the ink absorbing capacity becomes excessive. Since the recording density is reduced, high-quality image quality cannot be obtained. The amount of pigment used in the ink receiving layer is 4
It is preferably at least 0% by weight, particularly preferably at least 60% by weight.

In the present invention, it is preferable to provide a color forming layer containing colloidal silica as a main component on the ink receiving layer. In this case, from the viewpoint of improving the ink absorbency, the shape of the colloidal silica is preferably a non-spherical shape in which beads are connected in a bead shape or a ring shape. If necessary, an antifoaming agent, a cationic resin, or the like can be appropriately added as long as the effects of the present invention are not impaired.

The coating amount of the color forming layer is 1 to 6 g / m2 in solid content.
² , and more preferably 1.5 to 5 g / m ² . When the color-forming layer is less than 1 g / m ² , high recording density and glossiness cannot be obtained, and when it exceeds 6 g / m ² , ink absorbency decreases. Furthermore, in order to achieve silver halide photographic image reproduction, the 75-degree glossiness of the ink jet recording paper of the present invention is preferably 30% or more, and particularly preferably 35% or more.

As means for providing the ink receiving layer and the color forming layer on the support, various coating apparatuses such as a blade coater, a roll coater, an air knife coater, a bar coater, a curtain coater, a gravure coater and a gate roll coater can be used. Can be used. Further, as the surface finish, various calenders such as a machine calender, a soft calender, and a super calender can be used alone or in combination.

[0022]

The ink jet recording paper of the present invention has no metallic luster in the printed area, has excellent image light fastness, and has a glossy feeling even when recording is performed using an ink comprising a water-soluble dye. Paper. In particular, when a color-forming layer is provided, generally, metallic luster is easily generated.
The effects of the present invention appear remarkably.

[0023]

EXAMPLES Hereinafter, the specific structure of the recording paper of the present invention will be described with reference to examples, and the characteristics of the recording paper will be described in comparison with comparative examples. However, the present invention is not limited thereto. is not. In the examples, “parts” all represent “parts by weight”. The average primary particle diameter of the beaded colloidal silica is a value measured by a BET method, and the secondary particle length is a value measured by a laser scattering method.

Embodiment 1 FIG. 93 parts of hardwood bleached kraft pulp (L-BKP) having a freeness of 440 mlcsf and softwood bleached kraft pulp (N-BK) having a freeness of 520 mlcsf
P) A slurry comprising 7 parts, 7 parts of talc, 1.5 parts of a sulfuric acid band, 0.4 part of a sizing agent, and 0.02 part of a retention aid was prepared, and papermaking was performed by a conventional method using a twin-wire paper machine. After that, pre-drying was performed using a cylinder dryer, and then oxidized starch was applied on both sides to 4 g / m ² using a two-roll size press device, machine calendered, and smoothness was 35 seconds. With a basis weight of 160
g / m ² of base paper was obtained.

On this base paper, the following coating liquid 1 was applied to a solid content of 13 g / m ² using a Meyer bar coater, and then treated at a linear pressure of 80 kg / cm using a calender device. A receiving layer was provided. Further, the following coating liquid 2 was applied on the ink receiving layer at a rate of 2 g /
m ^2, and then treated with a calender at a linear pressure of 100 kg / cm, and a basis weight of 175 g / m ^2.
Was obtained. In addition, the composition of the coating liquids 1 and 2 is shown below, except for water, which is a solid content.

[0026]Coating liquid 1.  Synthetic silica (average secondary particle diameter: 4 μm): 100 parts Polyvinyl alcohol (PVA117: Kuraray Co., Ltd.)
15 parts water-soluble aluminum salt (aluminum sulfate 18 hydrate)
(Anhydrous content)): 0.34 parts (2.0 ion equivalent in terms of Al ion)
Lmol / pigment 100g) Water-soluble magnesium salt (magnesium sulfate heptahydrate (no
(Water content)): 0.20 parts (1.7 mM in terms of Mg ion)
Dye / pigment 100 g) Dye fixing agent (quaternary ammonium salt type polymer): 5 parts Water: 550 parts

[0027]1. coating liquid  Beaded colloidal silica (average primary particle size: 10 to 20)
nm, secondary particle length: 50 to 300 nm): 100 parts Water: 420 parts

Embodiment 2 FIG. The addition amount of magnesium sulfate heptahydrate (anhydrous component) used in coating solution 1 was 0.30 parts (Mg
An ink jet recording paper was obtained in exactly the same manner as in Example 1 except that the ion conversion was 2.5 mmol / 100 g of pigment.

Embodiment 3 FIG. The addition amount of aluminum sulfate 18 hydrate (anhydride) used in the coating liquid 1 was 0.21 part (A
An ink jet recording paper was obtained in exactly the same manner as in Example 2 except that the amount was 1.2 mmol / l ion conversion / 100 g of pigment.

Embodiment 4 FIG. An ink jet recording paper was obtained in exactly the same manner as in Example 1 except that the coating amount of the coating liquid 2 was changed to 5 g / m ² .

Embodiment 5 FIG. An ink jet recording paper was obtained in exactly the same manner as in Example 1 except that the coating amount of the coating liquid 2 was 9 g / m ² .

Embodiment 6 FIG. 0.8 g / m of coating amount of coating liquid 2
Except that a ² to obtain an ink jet recording paper in the same manner as in Example 1.

Embodiment 7 FIG. Other than not applying the coating liquid 2,
Inkjet paper was obtained in exactly the same manner as in Example 1.

Comparative Example 1 The addition amount of magnesium sulfate heptahydrate (anhydrous component) used in coating solution 1 was 0.40 parts (Mg
An ink jet recording paper was obtained in exactly the same manner as in Example 1 except that the ion conversion was 3.3 mmol / 100 g of pigment.

Comparative Example 2 The addition amount of magnesium sulfate heptahydrate (anhydrous component) used in coating solution 1 was 0.10 parts (Mg
An ink jet recording paper was obtained in exactly the same manner as in Example 1 except that the ion conversion was 0.8 mmol / 100 g of pigment.

Comparative Example 3 The addition amount of aluminum sulfate 18 hydrate (anhydride) used in the coating liquid 1 was 0.41 part (A
An ink jet recording paper was obtained in exactly the same manner as in Example 2 except that the amount was 2.4 mmol / l ion conversion / 100 g of pigment.

Comparative Example 4 The addition amount of aluminum sulfate 18 hydrate (anhydride) used in the coating liquid 1 was 0.14 parts (A
An ink jet recording sheet was obtained in exactly the same manner as in Example 2 except that the amount was changed to 0.8 mmol / l ion / 100 g of pigment.

Comparative Example 5 Example 1 was repeated except that the addition amount of magnesium sulfate heptahydrate (anhydrous component) used in the coating liquid 1 was 0 parts (0 mmol in terms of Mg ion / 100 g of pigment).
In the same manner as in the above case, an ink jet recording paper was obtained.

Comparative Example 6 The addition amount of aluminum sulfate 18 hydrate (anhydrous content) used in coating liquid 1 was 0 parts (0 mmol in terms of Al ion / 100 g of pigment), and the addition amount of magnesium sulfate heptahydrate (anhydrous content) was 0. An ink jet recording sheet was obtained in exactly the same manner as in Example 1 except that the amount was .48 parts (4.0 mmol in terms of Mg ion / 100 g of pigment).

The evaluation results of the ink jet recording papers obtained in Examples and Comparative Examples are as summarized in Table 1.
The evaluation symbols in the table can be used without any problem as long as they are ◎ and ○.

[Table 1]

(1) 75-degree specular glossiness The 75-degree specular glossiness was measured according to JIS P8142 using a specular gloss meter GM-26D manufactured by Murakami Color Research Laboratory.

(2) Inkjet recording test The recording test was performed using an inkjet printer (PM-750).
C, manufactured by Seiko Epson Corporation), and a predetermined solid and image pattern were recorded and evaluated according to the following criteria.

A. Image light resistance Light resistance tester (Xenon weather meter SC700-
(WN, manufactured by Suga Test Instruments Co., Ltd.), the recording density of the magenta ink after the treatment for 25 hours was measured, and the residual ratio of the recording density before the treatment was evaluated according to the following criteria. A: Recording density residual rate of 90% or more. ：: Recording density residual rate of 70% or more and less than 90%. Δ: Recording density residual rate of 50% or more and less than 70%. ×: Residual recording density rate of less than 50%.

B. Metallic gloss A black solid image pattern was printed, and the metallic gloss was visually evaluated according to the following criteria. A: No metallic luster is observed. ：: Almost no metallic luster is observed. Δ: Metal luster is slightly recognized. X: Metallic luster is remarkably recognized.

C. Recording Density A black solid image pattern was printed, and the recording density was measured using a Macbeth densitometer (RD915, manufactured by Macbeth).

D. Ink Absorbability A pattern in which solid images of magenta and green (mixed color of cyan and yellow) were adjacent to each other was printed, and bleeding (bleed) at the boundary was visually evaluated according to the following criteria. The bleeding at the boundary between magenta and green becomes black, which enables more strict evaluation. A: No bleeding was observed at the boundary. ：: Almost no bleeding was observed at the boundary. Δ: Bleeding was slightly observed at the boundary. X: Bleeding is remarkably observed at the boundary.

Continuation of the front page Examiner Sadafumi Noda (56) References JP-A-10-6639 (JP, A) JP-A-9-314989 (JP, A) JP-A-10-100531 (JP, A) JP JP-A-61-57379 (JP, A) JP-A-61-43593 (JP, A) JP-A-11-321088 (JP, A) JP-A-11-321090 (JP, A) A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (3)

(57) [Claims] 1. An ink jet recording paper comprising an ink receiving layer having a pigment and a binder as main components on at least one surface of a support, wherein the ink receiving layer is composed of a water-soluble aluminum salt (A) and It contains a water-soluble magnesium salt (M), and the content of each of the salts (A) and (M) in the ink receiving layer is 3 ≦ a + m ≦ 5 and 1 ≦ a ≦ 2
An ink jet recording sheet, characterized by being: Here, a is an aluminum ion conversion value (mmol / pigment 1)
00g), and m is a value in terms of magnesium ion (mmol / 100 g of pigment). 2. The ink jet recording paper according to claim 1, wherein a color forming layer mainly composed of colloidal silica is provided on the ink receiving layer. 3. The ink jet recording paper according to claim 1, wherein the 75 ° glossiness of the recording paper surface is 30% or more.