JPH05246131A - Ink jet recording paper - Google Patents

Abstract

PURPOSE:To obtain a paper for ink jet recording having high ink absorbability, high resolution, high ink absorbing speed and high coloring properties. CONSTITUTION:A paper for ink jet recording wherein there exist at least two peaks on the pore opening distribution curve of 0.2-10mum and 0.05mum or smaller of a paper consisting of a fibrous substance and a filler and the cumulative vol. of the pore opening of 0.05mum or smaller is at least 0.05ml/g. It is possible thereby to obtain a paper for ink jet recording having good balance of high ink absorbability, high resolution, high ink absorbing speed and high coloring properties and being ordinary paper-like.

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 paper, and more particularly to an ink jet recording paper having a high image density, a clear image color tone and a good resolution suitable for multicolor recording.

[0002]

2. Description of the Related Art In recent years, ink jet recording systems are characterized by high speed, low noise, easy multicoloring, great flexibility in recording patterns, and no need for development or fixing. It is rapidly spreading in various applications including hard copy devices. Furthermore, the image formed by the inkjet method is comparable to that of the normal multicolor printing, and when the number of copies is small, it is cheaper than the ordinary plate-making method. Instead, it is being tried to apply it to the fields of multicolor printing and color photography.

Since high-quality papers and coated papers used for general printing have extremely poor ink absorbency, the ink remains on the surface for a long time even after the completion of ink jet recording, and touches a part of the apparatus or a handling person. If the recording surface is rubbed due to overlapping of sheets ejected continuously or the like, the image is stained with the residual ink. Further, in the high-density image area, there is a problem that a large amount of ink is mixed or flowed out without being absorbed, which is not practical. That is, as the recording sheet, a high density and clear image can be obtained,
Moreover, it is required at the same time that the absorption of the ink is fast and the ink does not flow out, and that the resolution of the ink dots is suppressed by suppressing the lateral diffusion of the ink dots on the surface of the recording sheet.

Several proposals have hitherto been made to solve these problems. For example, Japanese Patent Laid-Open No. 52-
No. 53012 discloses an inkjet recording paper obtained by infiltrating a low-sized base paper with a paint for surface processing. Further, JP-A-53-49113 discloses an ink jet recording paper in which a sheet containing urea-formalin resin powder is impregnated with a water-soluble polymer. Further, JP-A-55-5830 discloses an ink jet recording paper having a support surface provided with an ink-absorptive coating layer, and JP-A-55-51583 discloses non-colloidal silica as a pigment in a coating layer. Is disclosed in Japanese Patent Application Laid-Open No. Sho 5
No. 5-146786 discloses an inkjet recording paper provided with a water-soluble polymer coating layer. Further, JP-A-55-11829 has a layer structure of two or more layers, the outermost layer has an ink absorbency of 1.5 to 5.5 mm / min, and the second layer has an ink absorbency of 5.5. A method of adjusting the spread of the ink dots and the absorption speed by setting it to 60.0 mm / min is disclosed.

[0005]

However, the technical idea represented by Japanese Patent Laid-Open No. 52-53012 is to obtain resolution by sacrificing ink absorbability to some extent. The technical idea as typified by No. 53-49113 has a drawback that although the ink absorbency and the resolution are obtained to some extent, the ink does not easily come out due to the deep penetration of the ink into the sheet layer. The sheet is not satisfactory.
Then, as a method for improving these drawbacks, Japanese Patent Laid-Open Publication No.
It has been considered to provide an ink-absorbent coating layer on the surface of a support as represented by No. 5-5830. It is true that an inkjet sheet that does not have a coating layer on its surface, that is, a pigment coating layer with greater ink absorption than a so-called high-quality paper type inkjet sheet, or a polymer coating layer that adsorbs coloring components in the ink is , The ink absorption, the resolution and the color reproducibility have been improved. However, while the inkjet recording sheet has been improved, the inkjet recording application and apparatus have also made remarkable progress and become faster, and accordingly, a large amount of ink is supplied to the same point of the inkjet recording sheet, and high speed is achieved. Inkjet recording with high resolution, high density, high ink absorption capacity, and high ink absorption speed, which not only absorbs a large amount of paper but also appears to be in a dry state immediately after the ink adheres because it requires sheet feeding. Sheets have come to be requested.

Further, ink jet recording is used in the field where high-quality paper is conventionally used depending on the application. In that case, as described above, a recording sheet provided with an ink-absorptive coating layer is not preferred, and it is like a high-quality paper. Inkjet sheets with high print quality are required. In order to obtain a high quality paper-like inkjet recording paper with high printing quality as described above, the inventors of the present invention have a surface with which the ink first comes in contact with a pore size of an appropriate size, and have a high resolution and a clear color tone. In order to maintain the above, it has been found that it is necessary to use an filler having a large specific surface area, that is, a filler having an extremely small primary particle diameter to form an ink receiver having an extremely large pore volume.

[0007]

The present invention relates to an ink jet recording paper having the following requirements having high ink absorption capacity, high resolution, high ink absorption speed and high colorability, and is particularly used for multicolor ink jet recording. High value.
That is, the peak of the pore distribution curve on the ink receiving surface of the ink jet recording paper prepared by adding a filler to the fibrous material and making with a paper machine has peaks of at least 0.2 to 10 μm and 0.05 μm.
It is an object of the invention to provide an inkjet recording paper characterized in that the cumulative volume of pores having a diameter of 0.05 m or less and 0.05 μm or less is 0.05 ml / g or more. Ink jet recording paper that meets the above requirements has a fast ink absorption speed and appears to be dry after ink is attached, and even if the human body or a part of the device does not stain the image with residual ink, it has a high resolution. It gives a clear image in color and is like high-quality paper.

The reason is that, in the ink which is instantly absorbed in the large voids formed by the fibrous substance, in the next step, primary particles having an average particle diameter of 0.2 μm or less are aggregated to form secondary and tertiary aggregates. It is presumed that this is because the pores are taken in by the voids formed by the filler having pores with an extremely large pore volume of 0.05 μm or less. When a substance having a primary particle size of 0.2 μm or less is used as a filler, a retention agent is usually used, and the primary particles have a secondary particle size of 1 to 100 μm
Since it is retained in the pulp fiber as a secondary agglomerate, it is possible to internally add the primary particles as it is.

In the present invention, the fibrous substance mainly comprises wood pulp, but if necessary, synthetic pulp, synthetic fiber, glass fiber and the like can be used together.

In the present invention, the filler includes synthetic silica, synthetic alumina, light calcium carbonate, zinc oxide, synthetic organic pigments, etc., preferably synthetic silica, synthetic alumina, which satisfy the requirements of the present invention. There is no particular limitation as long as it is a substance. In addition to these fillers having pores of 0.05 μm or less, calcium carbonate usually used,
Inorganic pigments such as kaolin (white clay), talc and titanium oxide, and organic pigments such as plastic pigments and urea-formalin resins can be used in combination. Hole 0.05μm
The addition amount of the filler having the following pores is such that the cumulative volume of pores having a diameter of 0.05 μm or less measured on the ink jet recording paper by the mercury penetration method is 0.05 ml / g or more, preferably 0.07 ml / g or more. However, it is preferable that the amount is usually 5% or more when measured as ash content.

In the present invention, a sizing agent, a dry paper strength improver, a wet paper strength improver, a retention improver, a drainage improver, a colorant, a defoaming agent and a slime control which are usually used in a papermaking process. There is no problem in adding agents and the like.

The ink jet recording paper according to the present invention produced in this manner has pore distribution curve peaks at two points of at least 0.2 to 10 μm and 0.05 μm or less, and pores of 0.05 μm or less. Cumulative volume of 0.0
It should be 5 ml / g or more.

The measurement of the pore distribution curve referred to in the present invention is performed by ME.
RCURY PRESSURE PROSIMETE
R MOD220 (manufactured by Carlo Erba Co., Ltd.) is used, and the so-called mercury injection method (more specifically, EW WASHBURN,
Proc.Natl.Acad.Sci., 7, p115 (1921), H.M. L. R
ITTER, L.A. E. DRAKE, Ind.Eng.Chem.Ana
L., 17, p782, p787 (1945), L.A. C. DRAKE, In
d. Eng. Chem., 41, p780 (1949), and H.M. P. GRA
CE, J. Amer.Inst.Chem.Engrs., 2, p307 (1956)
, Etc.) void volume distribution curve (Urano, “Surface” 13 (10), p588 (1975), Onogi, Yamauchi, Murakami, Imamura, Kappa Gikyo, 28, 99 ( 1974))
The pore size distribution (differential curve) of was calculated and obtained.

The surface tension of mercury is 482,536 dyne / cm,
The contact angle used is 141 °, and the absolute mercury pressure is 1 to 2000 kg / c.
The measurement was carried out by changing to m ² . For the measurement, about 1 g of the sample was precisely weighed, and the cumulative pore volume (ml / g) per unit sample was measured by the porosimeter described above. The dust was differentiated and plotted as the frequency with respect to the pore radius (μm). In the present invention, the cumulative pore volume (Vml / g) of 0.05 μm or less means a pore diameter of 0.05 μm in the cumulative pore volume curve of an inkjet recording sheet, that is, 150 kg of mercury pressure in this measuring method.
/ Cm ² at the time the cumulative pore volume of the (V150ml / g) and mercury pressure 2000 kg / cm ² at a cumulative pore volume (V2000ml / g) refers to the value given by the following equation. Cumulative pore volume (Vml / g) of 0.05 μm or less = V2000-V150. Since one peak of the pore distribution curve is in the range of 0.2 to 10 μm, the absorption of ink is extremely fast and the ink becomes apparently dry.
When the pore diameter is 10 μm or more, the ink absorbability is good but the circularity of the ink dot is lacking. On the other hand, when the pore diameter has a peak at 0.05 to 0.2 μm, the color tone due to irregular reflection of light is It is not preferable because a decrease occurs. Furthermore, if one peak of the pore distribution curve is not less than 0.05 μm, or even if there is a cumulative pore volume of 0.05 μm or less, 0.05 ml
If it is less than / g, the resolution of the image and the sharpness of the color tone cannot be obtained. The larger the cumulative pore volume of 0.05 μm or less, the more preferable. However, in order to increase the cumulative pore volume, it is necessary to increase the addition amount of the filler, which causes a decrease in strength. Therefore, in the present invention, 0.05 ml / g or more, more preferably 0.07 or more. It is more than ml / g.

[0015]

When the ink-jet recording paper of the present invention is used to print an image or print by an ink-jet method, the color tone of the ink is clear, the resolution is good, the absorption speed of the ink is fast, and it is practical for high-quality paper. A record of sufficient value is obtained. As described above, the present invention makes the ink-jet recording paper have a pore size within a specific range, and further has a cumulative pore volume not more than a specific pore size mainly due to the filler to be a specific value or more, thereby providing good absorbability. In addition, a high quality paper-like ink jet recording paper having a high absorption speed, clear color in the recorded image portion and good dot resolution can be obtained. Since these ink jet recording suitability tend to be contradictory to each other, for example, if absorption is made faster, sharpness of color tone is lost or resolution is poor. It has been found that the present invention can set these conflicting recording aptitudes in good ranges, and can obtain an inkjet recording paper having an excellent balance that is not present in any conventionally known inkjet recording paper.

[0016]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
In addition, the part shown in an Example means a weight part. The methods for measuring various inkjet suitability values in the examples are shown below.

(1) Resolution An ink droplet having a diameter of 100 μm of a water-based ink for ink jet is adhered to the surface, and after being absorbed, the area marked by the ink droplet is measured, and the value calculated as the diameter is assumed as a perfect circle. Used (μm). The smaller the diameter, the better the resolution. (2) Colorability With respect to four color water-based inks of cyan, magenta, yellow and black printed by an inkjet device, the density of each color was measured by a Sakura Densitometer PDA45. The higher the value, the better the color.

Comparative Example 1 70 parts of LBKP having a freeness of 350 ml, freeness of 390 ml
Pulp slurry consisting of 30 parts of NBKP, talc 2
5 parts were added, and 1 part of CatoF (cationized starch manufactured by Oji National Co., Ltd.) was added as a yield improver to obtain a basis weight of 70.
Paper of g / m ² was made with a Fourdrinier paper machine. Using this paper as an inkjet recording paper, the mercury penetration method and inkjet suitability were measured. The measurement results are shown in Table 1 below.

Comparative Example 2 70 parts of LBKP having a freeness of 350 ml and a freeness of 390 ml
20 parts of Pergopack M2 (fine powdered urea-formalin resin manufactured by Ciba-Geigy Co., Ltd.) was added to a pulp slurry consisting of 30 parts of NBKP, and 1 part of CatoF was added to make paper in the same manner as in Comparative Example 1, and a basis weight of 70 g / m ² of paper was obtained. Using this paper as an inkjet recording paper, the mercury penetration method and inkjet suitability were measured. The measurement results are shown in Table 1.

Example 1 90 parts of LBKP having a freeness of 350 ml, freeness of 390 ml
15 parts of VITASEAL # 1500 (synthetic silica manufactured by Taki Chemical Co., Ltd.) was added to a pulp slurry consisting of 10 parts of NBKP, and 1 part of CatoF was added to produce paper in the same manner as in Comparative Example 1, and the basis weight was 68 g / m ² . Got the paper. Using this paper as an inkjet recording paper, the mercury penetration method and inkjet suitability were measured. The measurement results are shown in Table 1.

[0021]

[Table 1]

[0022]

The measurement results of the examples show that the inkjet recording paper has excellent inkjet suitability.

Claims (1)

[Claims] 1. The peak of the pore distribution curve of paper composed of fibrous substance and filler is at least 0.2 to 10 μm and 0.
An ink jet recording paper, characterized in that the cumulative volume of pores of 0.05 μm or less and 0.05 μm or less is 0.05 ml / g or more.