JPH115360A - Recording sheet material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording sheet material having excellent ink absorbency and ink coloring characteristic with small drop of powder by improving a coating film strength. SOLUTION: In the recording sheet material comprising a base material and an ink receptive layer provided on the material, the layer contains whisker- like calcium carbonate so that particle size of the carbonate is 3 to 50 μm of a long diameter and 0.3 to 2.0 μm of a short diameter, an aspect ratio (long diameter/short diameter) is 5 to 50, BET specific surface area is 25 m<2> /g or less, and bulk of a value measured according to JIS K 5101 is 7.0 ml/g or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet material, and more particularly to a recording sheet material having a high image density, excellent ink absorbability, and a small amount of powder when cutting the recording sheet material.
The present invention relates to a recording sheet material useful for an ink jet system.

[0002]

2. Description of the Related Art Ink-jet recording is a method of recording images, characters, etc. by spraying ink droplets by various operations and attaching the droplets to a recording sheet material such as paper.
It has advantages such as low noise, easy multi-color printing, and large-format recording. At present, it is widely used in various fields such as various printers, facsimile machines and computer terminals, and is rapidly spreading.

In particular, various improvements have been made to the recording sheet material used in the ink jet recording system in terms of the ink composition of the ink jet recording apparatus so that paper used for ordinary printing and writing instruments can be used. However, with the improvement of inkjet recording performance such as high-speed and high-definition devices and the expansion of applications, higher performance is also required for recording sheet materials.

[0004] In the ink jet recording system, usually, an aqueous ink is used from the viewpoint of safety and hygiene, and the ink attached to the ink jet recording sheet material needs to be rapidly absorbed. That is, in the case of a color ink jet printer using a plurality of ink nozzles, it is necessary that a previously ejected ink droplet be absorbed by a sheet material before the next ink droplet is ejected. The material is required to have a high ink absorption capacity.

[0005] The performance required of the ink jet recording sheet material is as follows. (1) Absorption of ink: Ink is absorbed in a short time. (2) Print density: High optical density. (3) Print quality: dot edges must be sharp. (4) Color developing property: The color tone of the printed portion is good. (5) Transportability: There is little generation of paper dust and there is no transport failure. (6) Dimensional stability: no dimensional change and no curling after printing. (7) Paper texture: Smooth surface, high whiteness and good writability.

Several proposals have hitherto been made to satisfy these requirements. For example, in order to solve the above-mentioned problem (1), a coating layer contains silica powder or alumina powder having high ink absorbability. In this case, although the ink absorptivity of the recording paper can be improved, there is a disadvantage that the color developability is inferior because the smoothness and the gloss are insufficient.

As a method for improving the smoothness and glossiness of the recording paper, a method of applying a super calender to the surface of the recording paper and finishing the surface smoothly (Japanese Patent Laid-Open No. 57-1678).
No. 79) or a plasticizer which contains thermoplastic resin or thermoplastic resin particles in a recording paper, and after printing on the recording paper, applies heat or pressure to the recording paper or dissolves or swells the thermoplastic resin. And / or a method of treating the surface of the recording paper with an organic solvent (for example, JP-A-53-50744).
JP-A-59-196285, JP-A-59-204
591, JP-A-59-202891, JP-A-59-202891
204591, JP-A-59-204592 and JP-A-59-222381). However, these methods can improve the smoothness and glossiness of the recording paper, but have the disadvantage of reducing the ink absorbency.

On the other hand, there has been proposed a method in which a specific amount of calcium carbonate composite silica is used together with another pigment as a pigment in a coating layer provided by a casting coating method. In this case, however, the ink absorbency, the color developing property, and the print density can be satisfied, but there is a problem in that the strength of the coating film is reduced and powder fall occurs. In particular, recently, the transport speed of the printer is high, and powder dropping may cause troubles due to clogging of inkjet nozzles.

In order to prevent powder falling, a method has been proposed in which a silicon-containing water-soluble polymer and a porous inorganic pigment are used in combination (Japanese Patent Application Laid-Open No. Sho 62-273881). However, in this method, the powder absorption was prevented by the polymer, and the ink absorption was insufficient.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and improves the strength of a coating film by blending a specific whisker-like calcium carbonate to prevent powder falling. It is possible to maximize the characteristics of the porous inorganic pigment used in combination, and simultaneously achieve the above-mentioned requirements in recording a color image using a plurality of color inks by an ink jet recording method, in particular, ink absorption and ink color development. An object of the present invention is to provide a recording sheet material that can be satisfied.

[0011]

That is, the present invention provides a recording sheet material comprising a base material and an ink receiving layer provided on the base material, wherein the ink receiving layer contains whisker-like calcium carbonate. The whisker-like calcium carbonate has a particle diameter of 3 to 50 μm in major axis and 0.3 to 2.0 in minor axis.
μm, the aspect ratio (major axis / minor axis) is 5 to 50,
The BET specific surface area is 25 m ² / g or less and the bulk is JIS
The recording sheet material has a content of 7.0 ml / g or more as measured by K5101. The present invention includes a specific whisker-like calcium carbonate, thereby preventing the porous inorganic pigment from falling off and maximizing the ink absorbency, which is the original characteristic of the porous inorganic pigment. This solves the conflicting problem between absorbency and coating strength.

The recording sheet material of the present invention is obtained by using a conventionally known plain paper, processed paper, synthetic paper, plastic film or the like as a base material and providing the ink receiving layer on the base material.

The whisker-like calcium carbonate used in the present invention is disclosed in, for example, JP-A-3-88714 and JP-A-4-321.
It may be manufactured by the method described in No. 515 or the like, and is mixed with the coating resin composition as a water slurry or powder.
The whisker-like calcium carbonate used in the present invention has a major axis of 3 to 50 μm, preferably 5 to 40 μm, and a minor axis of 0.3.
To 2.0 µm, preferably 0.5 to 1.6 µm.
If the major axis is less than 3 μm and the minor axis is less than 0.3 μm, powder fall cannot be prevented. On the other hand, when the major axis exceeds 50 μm and the minor axis exceeds 2.0 μm, the surface smoothness is inferior, so that the coloring property as a recording sheet material is inferior. In addition, the particle diameter of the whisker-like calcium carbonate refers to an average of values measured by an electron microscope.

The BET specific surface area of the whisker-like calcium carbonate used in the present invention is 25 m ² / g or less, preferably 20 m ² / g. BET specific surface area is 25m ² /
When it is larger than g, the viscosity of the coating resin composition increases and powder dropping cannot be prevented.

The aspect ratio of the whisker-like calcium carbonate is 5 to 50. If it is less than 5, powder falling cannot be prevented, and if it exceeds 50, whiskers are entangled, and the dispersibility of the coating resin composition is poor, and the workability during coating is poor.

The bulk of the whisker-like calcium carbonate is 7.0 ml / g or more as measured according to JIS K5101 “Pigment test method, apparent specific volume (static method)”. If the bulk is less than 7.0 ml / g, powder drop cannot be prevented.

The surface treatment of the whisker-like calcium carbonate used in the present invention may be performed, if necessary, with a fatty acid, rosin,
The surface treatment may be performed with a surfactant such as αβ unsaturated carboxylic acid, or a titanate or silane coupling agent.

In the present invention, the ratio of the whisker-like calcium carbonate to the porous inorganic pigment is preferably in the range of 3:97 to 50:50, more preferably 5:95 to 40:60.
Range. Whisker-like calcium carbonate ratio of 3
If less, it will not be able to demonstrate the prevention of powder drop,
On the other hand, when the ratio of the whisker-like calcium carbonate is more than 50, the coloring property at the time of recording tends to deteriorate.

Examples of the porous inorganic pigment used in the present invention include synthetic amorphous silica, synthetic spherical silica, calcium phosphate compound, synthetic alumina, clay, talc, diatomaceous earth, fine particle calcium carbonate, calcium sulfate, barium sulfate, satin white, Examples thereof include aluminum silicate and calcium carbonate composite silica. These may be used alone or in combination of two or more. Synthetic silica is particularly preferable because of excellent color developing properties and ink absorption. In addition, when synthetic spherical silica is used as the porous inorganic pigment, it is possible to form an interparticle space optimal for ink absorption and a pore structure suitable for dye adsorption, and further, a whisker-like calcium carbonate in the ink receiving layer. And a stronger ink receiving layer is formed. As the synthetic spherical silica used in the present invention, the average diameter of the secondary particles is 1.0 to 100 μm, and the average internal pore diameter is 30 to
Those in the range of 400 ° are particularly preferred.

The ink receiving layer in the present invention is prepared by adding whisker-like calcium carbonate, a porous inorganic pigment, a water-soluble polymer, a polymer emulsion, an organic solvent-soluble resin, etc. to a coating liquid for a recording sheet. The working liquid is applied on a substrate and dried.

The water-soluble polymer used in the present invention includes:
Examples thereof include starch, gelatin, casein, gum arabic, sodium alginate, carboxymethylcellulose, polyvinyl alcohol, polyvinylpyrrolidone, and sodium polyacrylate. These may be used alone or in combination of two or more.

The polymer emulsion used in the present invention includes styrene-butadiene latex, acrylonitrile-butadiene latex, methyl methacrylate-
In addition to polymer latexes such as butadiene latex, vinyl acetate latex, and ethylene vinyl acetate latex, polyethylene emulsions, polystyrene emulsions, ionomer emulsions and the like can be mentioned, and these can be used alone or in combination of two or more. Further, one or more of various additives such as a dispersant, a fluorescent dye, a ph regulator, an antifoaming agent, a lubricant, a preservative, a surfactant, and a waterproofing agent are used as necessary.

Among the above components, the water-soluble polymer, polymer emulsion and organic solvent-soluble resin used as a binder are 3 to 3 parts by weight per 100 parts by weight of whisker-like calcium carbonate, porous inorganic pigment and other additives. 100 parts by weight, preferably 10 to 80 parts by weight, is used, but the ratio is not particularly limited as long as the amount is sufficient for binding of these fillers.

The solid content of the coating solution is preferably in the range of about 1 to 50% by weight. The coating liquid is applied on the substrate by a known method, for example, a roll coater method, a blade coater method, an air knife coater method, or the like, usually in an amount of about 1 to 50 g / m ² (dry coating amount). Preferably, about ² to 30 g / m ² (dry coating amount) is applied.

A recording sheet material provided with an ink receiving layer on a substrate can be used as it is as a recording sheet material in the present invention, but if necessary, it can be further provided with a surface smoothness using a super calender or the like. is there.

[0026]

The present invention will be described below in detail with reference to examples and comparative examples, but these examples do not limit the present invention.

Example 1, Comparative Examples 1-3 Using a high-quality paper having a basis weight of 80 g / m ² as a base material, a coating solution prepared according to the formulation shown in Table 1 was dried at a coating amount of 20 g / m ² . Coating was performed by a blade coater method at a ratio and dried by a conventional method to obtain a recording sheet material.

Using the above recording sheet material, ink jet recording was performed by an ink jet printer (manufactured by Canon), and the ink jet recording characteristics were evaluated by the following method. Table 1 shows the results.

(1) Color Chromogenicity The color clarity of the ink jet recorded image was visually evaluated,
It was evaluated on a 4-point scale according to the following criteria. ：: Extremely clear. ：: Clear. Δ: Slightly unclear. X: Very unclear.

(2) Color Density Cyan solid printing was measured with a Macbeth densitometer TR-524.

(3) Ink Absorption Using an inkjet printer, ink bleed (flow)
The number of hits (the number of overwriting) until the occurrence of was measured, and the best one was marked with ◎, the worst one was marked with ×, ◎, ○, △, ×
Was evaluated by ranking.

(4) Coating strength The surface of the ink receiving layer of the recording sheet material is made of 3H, H, and HB.
Writing was performed with a pencil of a book, and those that were powdered were evaluated as x, and those that were not powdered were evaluated as o.

(5) The dot diameter was measured using a stereo microscope.

[0034]

[Table 1]

Examples 2 to 3 and Comparative Example 4 As shown in Table 2, except that the amount of the whisker-like calcium carbonate was changed to prepare a coating solution, Example 1 and Comparative Examples 1 to 3 were performed.
In the same manner as in the above, a recording sheet material was obtained, and ink jet recording characteristics were evaluated. Table 2 shows the results. The results of Example 1 are also shown.

[0036]

[Table 2]

As is evident from the above results, the addition of the specific whisker-like calcium carbonate maximizes the effect of the porous inorganic pigment, prevents powder from falling off the coating film, and improves the ink jet recording method. , The physical properties required for recording a color image using a plurality of color inks, in particular, the ink absorbency and the color developability can be simultaneously satisfied.

[0038]

The recording sheet material of the present invention satisfies various requirements, such as high image density and excellent ink absorbency, and has little powder loss during conveyance and cutting of recording paper. Useful for high performance.

Claims (2)

[Claims] 1. A recording sheet material comprising a base material and an ink receiving layer provided on the base material, wherein the ink receiving layer contains whisker-like calcium carbonate, and a particle diameter of the whisker-like calcium carbonate. But the major axis 3-50μ
m, the minor axis is 0.3 to 2.0 μm, the aspect ratio (major axis / minor axis) is 5 to 50, the BET specific surface area is 25 m ² / g or less, and the bulk is 7 as measured by JIS K5101. A recording sheet material having a density of at least 0.0 ml / g. 2. The ink receiving layer contains a whisker-like calcium carbonate (A) and a porous inorganic pigment (B).
The recording sheet material according to claim 1, wherein the weight ratio of (B) is in the range of 3/97 to 50/50.