JP2003200650A - Inkjet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording sheet, which is excellent in lustrous properties under the condition that an excellent ink absorbency is kept unchanged and can prevent cracks from developing at the coating and drying in the formation of an ink accepting layer. <P>SOLUTION: In the inkjet recording sheet, on at least one side of the base material sheet of which the fine silica particle-containing ink accepting layer is formed, the fine silica particles, the average particle diameter of which is 30 nm or less, are employed as the fine silica particles. At the same time, the ink accepting layer includes a swelling clay compound, which is pulverized to a state that the average particle diameter of secondary particles is 300 nm or less, as an inorganic binder. The preferable loadings of the swelling clay compound to 100 pts.wt. of the fine silica particles lie within the range of 1 to 35 pts.wt. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ink jet recording sheet having an ink receiving layer formed on at least one side of a substrate sheet.

[0002]

2. Description of the Related Art As one of methods for outputting image information and character code information created by a personal computer or the like to a recording medium such as paper or OHP film, ink containing a water-soluble dye is used as a recording nozzle of a printer. In addition, an inkjet recording method in which an electric field, heat, pressure or the like is ejected as a driving source onto the surface of a recording medium to form an image is mentioned.

For a recording paper (inkjet recording sheet) used in such an ink jet recording system, the ink absorption speed is fast, the ink does not flow out or bleed even when the printing dots overlap, and It is required that the density is high, the color tone is bright and vivid, the lateral diffusion of the print dots is not unnecessarily large, and the edges of the print dots are smooth and not blurred. In particular, when the ink absorption speed of the recording paper is slow, the ink droplets mix with other ink droplets before being absorbed by the ink receiving layer, causing uneven printing such as cissing and bleeding, resulting in a marked decrease in image quality. To do. Therefore, whether or not it has high ink absorbency is a particularly important issue for the inkjet recording sheet.

In order to meet the above requirements, many ink jet recording sheets have been conventionally proposed. For example, a recording paper obtained by wetting a low-size base paper with a coating material for surface processing (Japanese Patent Laid-Open No. 52-53012), and a recording paper having an ink-absorbing coating layer on the surface of a support (Japanese Patent Laid-Open No. 55-5
No. 830), recording paper containing non-colloidal silica powder as a pigment in the underlayer (JP-A-56-157), recording paper in which an inorganic pigment and an organic pigment are used in combination (Japanese Patent Publication No. 57-10).
No. 7878), recording paper having two pore distribution peaks (Japanese Patent Laid-Open No. 58-110287), recording paper consisting of two upper and lower porous layers (Japanese Patent Laid-Open No. 62-111782), and fine powder layer. Recording paper having
No. 786, No. 61-148092, No. 62-1
149475, etc.), recording paper containing pigments or silica fine particles having specific physical properties (Japanese Patent Laid-Open No. 63-252).
779, JP-A-1-108083, and 2-
No. 136279, No. 3-65376, No. 3-
No. 27976), and recording paper containing silica fine particles such as colloidal silica (Japanese Patent Laid-Open Nos. 57-14091, 60-219083, and 60-21098).
4, gazette 61-20797 gazette, gazette 61-188.
183, JP-A-5-278324 and 6-
No. 92011, No. 6-183134, No. 7-
137431, 7-276789, etc.),
Recording paper containing fine particles of hydrated alumina (Patent Document 2)
No. 276671, No. 3-67684, No. 3-
No. 215082, No. 3-251488, No. 4
No. 6,798,86, No. 4,263,983, No. 5
No. 16517, etc.) has been proposed.

Most of these recording papers are void type ink jet recording sheets in which the ink receiving layer (ink absorbing layer) has a void structure. Alumina hydrate fine particles and silica fine particles are mentioned as one of the substances forming the void structure. However, when alumina fine particles are used, there is a problem that the production cost becomes high. When used, not only is it easy to form a void structure, but it is also available at a relatively low cost, and its primary particle size is 50
If the thickness is less than or equal to nm, there is an advantage that the sheet gloss of the inkjet recording sheet and the ink absorbency can be compatible. A void type inkjet recording sheet using such silica fine particles is a support obtained by dispersing silica fine particles in a water-soluble binder such as polyvinyl alcohol to obtain a support called ordinary paper or inkjet recording paper. It is manufactured by providing a porous ink-receiving layer by applying the composition on the above and drying it. Further, regarding silica fine particles, it has been proposed to use secondary fine particles having an average particle diameter of 10 to 150 nm in which primary fine particles having an average particle diameter of 3 to 40 nm are aggregated (JP-A-10-7).
1764).

On the other hand, as a support for ink jet recording sheets, a paper support has been used for many years. In recent years, however, a silver salt photographic tone recording sheet has been demanded.
A support having a high surface smoothness and good water resistance, for example, a resin film support such as a polyester film, a resin-laminated paper obtained by laminating a polyolefin resin or the like on both sides of paper has been used. Due to this, cockling after printing, which was a problem with the paper support,
It is possible to greatly improve the texture, gloss and water resistance.

[0007]

However, when silica fine particles are used in the void layer, a recording sheet having a certain degree of gloss can be obtained, but on the other hand, since the fine particles are fine particles, cracks occur during coating and drying. It is easy and it is hard to say that the gloss is comparable to that of silver halide photography.

When a water resistant support is used,
Unlike the case of using paper, the support itself does not absorb ink, so by coating a relatively thick coating for the ink receiving layer on the support to form a thick ink receiving layer, sufficient ink absorption is achieved. However, if the coating thickness of the ink-receiving layer coating material is increased, there is a problem that cracks tend to occur when the coating material is dried. The problem is that when a water resistant support having a higher smoothness is used, the ink receiving layer is not completely fixed on the support but easily moves during coating and drying of the ink receiving layer coating material. for,
This is especially noticeable.

In order to suppress cracking, it has been attempted to increase the ratio of the binder resin component such as polyvinyl alcohol to the inorganic binder such as silica fine particles in the ink receiving layer, but the void structure in the ink receiving layer. However, there is a problem that the ink absorbency is deteriorated.

As described above, in the conventional ink jet recording sheet, none of the present invention satisfies all the properties of good gloss, prevention of cracks during coating and drying, and good ink absorbability at the same time. is there.

The present invention is intended to solve the above-mentioned problems of the prior art, and provides an ink jet recording sheet which is excellent in ink absorption and glossiness and does not cause cracks in the ink receiving layer during production. With the goal.

[0012]

Means for Solving the Problems The present inventors have found that in an ink receiving layer in which silica fine particles are dispersed in a binder resin,
When the compounding ratio of the binder resin is reduced to improve the ink absorbency, cracks are likely to occur in the ink receiving layer, but silica fine particles having a specific primary particle diameter are used and a specific secondary binder is used as an inorganic binder. By using a swelling clay compound having a particle size in combination, it is possible to impart good ink absorbability and gloss to the ink receiving layer containing silica fine particles, even if the blending ratio of the binder resin is reduced.
Moreover, they have found that cracks can be prevented from occurring in the ink receiving layer during manufacturing, and have completed the present invention.

That is, according to the present invention, in an ink jet recording sheet in which an ink receiving layer containing silica fine particles is formed on at least one surface of a substrate sheet, the average particle diameter of primary particles of the silica fine particles is 30 nm or less, Also provided is an ink jet recording sheet characterized in that the ink receiving layer contains a swelling clay compound in which secondary particles have an average particle size of 300 nm or less as an inorganic binder.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The ink jet recording sheet of the present invention comprises
It is an inkjet recording sheet in which an ink receiving layer is formed on at least one surface of a base sheet. Here, in the ink receiving layer, silica fine particles having an average particle diameter of primary particles of 30 nm or less and an average particle diameter of secondary particles of 3 as an inorganic binder are used.
And a swelling clay compound finely divided to a size of 00 nm or less.

In the present invention, as the silica fine particles used in the ink receiving layer, precipitation method silica fine particles synthesized by an ordinary wet method, silica fine particles produced by a gel method, colloidal silica fine particles or a dry method, for example, a gas phase Examples include silica fine particles synthesized by the method. Among them, colloidal silica fine particles and silica fine particles synthesized by a vapor phase method can be preferably used. In particular, silica fine particles synthesized by a vapor phase method, which can be easily made into fine particles down to the level of primary particles and which can realize a high porosity, can be preferably used. Here, a flame hydrolysis method is mentioned as a general method for synthesizing silica fine particles by a gas phase method, and specifically, a method of burning silicon tetrachloride with hydrogen and oxygen is mentioned.

In the present invention, the average particle size of primary particles of silica fine particles used in the ink receiving layer is as follows.
It is 30 nm or less, preferably 5 to 15 nm. When the primary particle size of the silica fine particles exceeds 30 nm, the ink absorbency is lowered, and further the light transmittance (transparency) of the receiving layer is lowered, so that the density of the printed image is lowered and the image becomes unclear, which is not preferable. . Specific examples of silica fine particles synthesized by a vapor phase method in which the average particle diameter of primary particles is 5 to 15 nm include
Examples include those specified by trade names QS series (Tokuyama Corporation) and Aerosil series (Japan Aerosil Co., Ltd.).

The average primary particle diameter of the silica fine particles is 3
Those having a thickness of less than nm are difficult to manufacture and are difficult to obtain stably.

In the present invention, the fine silica particles used in the ink receiving layer, for example, fine silica particles synthesized by the gas phase method, are usually present as secondary particles formed by aggregating primary particles. The average particle size of the secondary particles is 250 nm to improve the surface gloss.
Until the following, it is preferable to use a known atomizing device (for example, a high-speed mixer having a shear rate of 15 m / s or more, a high-pressure homogenizer, an ultrasonic homogenizer, etc.) to atomize and pulverize.

In the present invention, the swelling clay compound used as the inorganic binder in the ink receiving layer is preferably a layered inorganic polymer having an ion exchange ability because it has a function of fixing the dye in the ink jet ink. There is no particular limitation on the shape, and the shape is amorphous, layered, needle-shaped,
Any shape such as a sphere can be used. In addition, it is preferable to select the type of the swelling clay compound according to the ionicity of the dye used in the inkjet ink. For example, when the water-soluble dye used in the inkjet ink is an anionic dye, it is preferable to use an anion-exchangeable layered inorganic polymer, and when the water-soluble dye is a cationic dye, a cation is used. It is preferable to use an exchangeable layered inorganic polymer.

Specific examples of the swelling clay compound usable in the present invention include hydrotalcite group minerals and smectite group clay minerals. These are layered inorganic polymers made of AlO ₆ octahedral sheet, and both natural and synthetic products can be used. These chemical compositions are magnesium aluminum hydroxide carbonate, and specific examples thereof include those specified by trade names KW2100 and KW2200 (both are Kyowa Chemical Industry Co., Ltd.).

Clay minerals of the smectite group can be further classified into several types, such as montmorillonite, hectorite, beidellite, sauconite, iron saponite, saponite, nontrolite hectite, etc., depending on their composition, but basically they are SiO ₄ tetrahedra. The sheet is formed by stacking unit layers having a three-layer structure in which an AlO ₆ octahedral sheet or a MgO ₆ octahedral sheet is sandwiched. Specific examples of the clay mineral of the smectite group include, for example, Laponite manufactured by Nippon Silica Co., Ltd. and Cope Chemical Co., Ltd.
And synthetic smectite manufactured by Kunimine Industry Co., Ltd.

The swelling clay compounds which can be used in the present invention are
Usually, the primary particles are present as agglomerated secondary particles, but in order to improve the surface gloss of the inkjet recording sheet and prevent cracks during coating and drying when forming the ink receiving layer, the average of the secondary particles is A particle having a particle diameter of 300 nm or less is used. This is because the average particle size of the secondary particles is 30.
This is because if it exceeds 0 nm, cracks are likely to occur during coating and drying when forming the ink receiving layer, and it is difficult to obtain good gloss on the surface of the inkjet recording sheet. Here, the average particle diameter of the primary particles of the swelling clay compound is preferably 80 nm or less. If it exceeds 80 nm, cracking tends to occur during coating and drying when forming the ink receiving layer, and it tends to be difficult to obtain good gloss on the surface of the inkjet recording sheet.

The swelling clay compound can be micronized by a known micronizing device (for example, a high-speed mixer having a shear rate of 15 m / s or more, a high-pressure homogenizer, an ultrasonic homogenizer, etc.), but it is more efficient. In order to obtain a finely divided product, it is preferable to use a medium stirring type disperser.

In the present invention, if the content of the swelling clay compound in the ink receiving layer is too low, cracks during coating and drying of the ink receiving layer are not prevented and the gloss of the ink jet recording sheet is not sufficient, and too high. Since the ink absorbency of the ink receiving layer is lowered, it is preferably 1 to 35 parts by weight, more preferably 5 to 25 parts by weight, based on 100 parts by weight of the silica fine particles.

In the present invention, the binder resin used in the ink receiving layer may be the binder resin used in conventional ink jet recording sheets. For example, cellulose derivatives such as oxidized starch, etherified starch, carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein, polyvinyl alcohol and their derivatives; maleic anhydride resin, ordinary styrene-butadiene copolymer; methyl methacrylate. -Conjugated diene-based polymer latex such as butadiene copolymer; Acrylic-based polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester; Vinyl-based polymer latex such as ethylene-vinyl acetate copolymer Or a functional group-modified polymer latex with a functional group-containing monomer such as carboxyl group of these various polymers; thermosetting resin such as melamine resin, urea resin; other polymethylmethacrylate, polyurethane resin, unsaturated poly Ester trees sunny, vinyl chloride - vinyl acetate copolymer, polyvinyl butyral, alkyd resins. These are 1 type alone or 2
A combination of two or more species can be used.

Particularly preferable binder resins include completely or partially saponified polyvinyl alcohol and various modified polyvinyl alcohols, and among them, partially saponified polyvinyl alcohol having a saponification degree of 85 to 95 mol% is preferable. Among these partially saponified polyvinyl alcohols, those having an average degree of polymerization of 500 to 4000 are particularly preferable in order to improve the film-forming property and the film brittleness, and in order to improve the cracks during coating and drying. More preferably, the average degree of polymerization is 1700 to 3500.

When polyvinyl alcohol is used in the ink receiving layer, another binder resin may be used in combination within the range that does not impair the effects of the present invention. The amount of the other binder resin used is usually preferably 40 parts by weight or less with respect to 100 parts by weight of polyvinyl alcohol.

In the present invention, the content of the binder resin in the ink receiving layer is preferably 10 to 40 parts by weight, more preferably 15 parts by weight with respect to 100 parts by weight of silica fine particles.
~ 30 parts by weight.

In the present invention, the ink receiving layer may contain known additives in addition to the above-mentioned essential components such as silica fine particles, a swelling viscosity compound and a binder resin. For example, a cationic substance, a hardening agent, a dispersant,
Leveling agents, preservatives, viscosity stabilizers, pH adjusters, plasticizers, UV absorbers, optical brighteners, oil drops such as hydrophobic high boiling point organic solvents, other hydrophilic resins, dispersion resins, emulsion resins, etc. Can be blended.

In the present invention, the thickness of the ink receiving layer is
If it is too thin, when a large amount of ink is ejected to the ink receiving layer, the ink droplets mix with other ink droplets before they are absorbed by the ink receiving layer, causing uneven printing such as cissing and bleeding, thus improving the image quality. If it is too thick and too thick, the ink absorbency is improved, but cracks are likely to occur during coating and drying when forming the ink receiving layer. Therefore, it is preferably 10 g / m ² or more in terms of solid content of the ink receiving layer. The thickness is more preferably 15 to 40 g / m ² .

As the support for the ink jet recording sheet of the present invention, a conventional ink jet recording sheet support can be used. For example, a known paper support, plastic support, composite support, etc. can be used. Can be appropriately used, but in order to obtain a clear image at a higher printing density, it is preferable to use a hydrophobic support which does not allow the ink liquid to penetrate into the support.

Specific examples of the plastic support include polyester (eg, polyethylene terephthalate),
A transparent plastic film made of a material such as cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, polyimide is mentioned. Of these, polyethylene terephthalate film is preferable. As a preferable thickness of such a transparent plastic film,
It is about 50 to 300 μm.

In the case of producing a more silver salt photographic ink jet recording sheet, resin-coated paper having a polyolefin resin coating layer in which a white pigment or the like is added to at least one of base papers, that is, RC paper is used as a support. It is preferable to use as.

Further, various back coat layers can be coated on the support on the side opposite to the ink receiving layer for antistatic property, transport property, curl preventive property and the like. The back coat layer may contain an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder resin, a latex, a curing agent, a pigment, a surfactant and the like in an appropriate combination.

The ink jet recording sheet of the present invention comprises
A coating material for an ink receiving layer in which silica fine particles and a swelling clay compound are uniformly dispersed in a binder resin, a known coater on a support, for example, a curtain coater, an air knife coater, a roll coating coater, a slide bead coater, a rod. It can be manufactured by coating with a bar coater or the like and drying.

The silica fine particles and the swelling clay compound may be dispersed at the same time or separately. When they are carried out separately, it is preferable to further carry out a dispersing operation after mixing the respective dispersions.

In the ink jet recording sheet of the present invention, the ink receiving layer may be composed of two or more layers. In this case, these ink receiving layers may have the same structure or different structures. Good. In addition to the ink receiving layer, an ink fixing layer, an undercoat layer, an intermediate layer, a protective layer and the like similar to those of conventional ink jet recording sheets may be appropriately provided.

[0039]

EXAMPLES The present invention will be specifically described below with reference to examples, but the contents of the present invention are not limited to the examples.
In addition, when "part" is described in the unit, it means a solid content part by weight.

Reference Example 1 (Preparation of Dispersion Liquid) <Silica Fine Particle Dispersion Liquid> Of the components shown in Table 1, ion-exchanged water, isopropyl alcohol, a defoaming agent and borax were mixed, and the mixture was stirred with a stirrer. On the other hand, vapor phase silica was added thereto, and polyvinyl alcohol was further added. The obtained mixture was mixed with a high pressure homogenizer (15 MR
-8TA, Doei Shoji Co., Ltd., was crushed 5 times at a pressure of 500 Kg / m ² to prepare a milky white dispersion liquid.

[0041]

[Table 1] Ingredients parts by weight gas phase method silica (average particle diameter of primary particles 7 nm) 100 (Aerosil A-300, Nippon Aerosil Co., Ltd.) Dispersant (SD10, Toagosei Co., Ltd.) 1 Borax 2 Polyvinyl alcohol (saponification degree 88 %, Average degree of polymerization 3500) 25 Defoamer (Surfynol GA, Nissin Chemical Industry Co., Ltd.) 0.01 Isopropyl alcohol 100 Ion-exchanged water 840

<Swelling Clay Compound Dispersion (A)> Of the components shown in Table 2, ion-exchanged water and a dispersant were mixed, and hydrotalcite was added thereto while stirring the mixture with a stirrer. The obtained mixture was circulated in a medium stirring type disperser (Nanomill (0.6 L), Asada Iron Works Co., Ltd.) so that the average residence time was 40 minutes to prepare a milky white dispersion liquid.

The average particle size of the secondary particles of the swelling clay compound dispersed in the obtained dispersion was measured by a laser Doppler particle size analyzer (Microtrac UPA, Nikkiso Co., Ltd.). , 95 nm.

[0044]

[Table 2] Ingredients By weight Hydrotalcite 100 (KW2200, Kyowa Chemical Industry Co., Ltd.) Dispersant (SD10, Toagosei Co., Ltd.) 1 Ion-exchanged water 570

<Swellable clay compound dispersion (B)> Swellable clay compound dispersion (B) except that the average residence time of the swellable clay compound dispersion (A) in a medium stirring type disperser was changed to 10 minutes. A milky white dispersion liquid was prepared by repeating the same operation as in the preparation of A), and the average particle diameter of the secondary particles of the swelling clay compound dispersed in the dispersion liquid was measured. It was 260 nm.

<Swellable clay compound dispersion (C)> Swellable clay compound dispersion (C) except that the average residence time of the swellable clay compound dispersion (A) in a medium stirring type disperser was changed to 5 minutes. A milky white dispersion liquid was prepared by repeating the same operation as in the preparation of A), and the average particle diameter of the secondary particles of the swelling clay compound dispersed in the dispersion liquid was measured. , 320 nm.

<Swelling Clay Compound Dispersion (D)> Of the components shown in Table 3, ion-exchanged water and a dispersant were mixed, and the mixture was stirred with a stirrer, and synthetic hectorite was added thereto. The obtained mixture was circulated in a medium stirring type disperser (Nanomill (0.6 L), Asada Iron Works Co., Ltd.) so that the average residence time was 10 minutes to prepare a translucent dispersion liquid.

The average particle size of the secondary particles of the swelling clay compound dispersed in the obtained dispersion was measured by a laser Doppler particle size analyzer (Microtrac UPA, Nikkiso Co., Ltd.). , 110 nm.

[0049]

[Table 3] Ingredients by weight Synthetic Hectorite 100 (Laponite RDS, Nippon Silica Industry Co., Ltd.) Dispersant (SD10, Toagosei Co., Ltd.) 1 Ion-exchanged water 910

<Swellable clay compound dispersion (E)> A swellable clay compound dispersion except that the average residence time of the swellable clay compound dispersion (D) in a medium stirring type disperser was changed to 5 minutes. A milky white dispersion liquid was prepared by repeating the same operation as the operation for preparing (D), and the average particle diameter of the secondary particles of the swelling clay compound dispersed in the dispersion liquid was measured. However, it was 185 nm.

<Swellable Clay Compound Dispersion (F)> The swellable clay compound dispersion (D) was replaced with a medium stirring type disperser.
A milky white dispersion liquid is prepared by repeating the same operation as the operation for preparing the swelling clay compound dispersion liquid (D), except that the shearing speed is 25 m / s for 10 minutes with a high-speed stirrer. Furthermore, the average particle size of the secondary particles of the swelling clay compound dispersed in the dispersion was measured to find 3
It was 10 nm.

<Calcium Carbonate Dispersion (G)> Of the components shown in Table 4, ion-exchanged water and a dispersant were mixed, and calcium carbonate was added thereto while stirring the mixture with a stirrer. The average residence time of the obtained mixture was 6 using a medium stirring type disperser (Nanomill (0.6 L), Asada Iron Works Co., Ltd.).
Circulation treatment was performed for 0 minutes to prepare a translucent dispersion liquid.

The average particle size of the secondary particles of the swelling clay compound dispersed in the obtained dispersion was measured by a laser Doppler particle size analyzer (Microtrac UPA, Nikkiso Co., Ltd.). , 820 nm.

[0054]

[Table 4] Ingredients by weight Calcium carbonate 100 (Shiraglossa DD, Shiraishi Calcium Co., Ltd.) Dispersant (SD10, Toagosei Co., Ltd.) 1 Ion-exchanged water 940

Reference Example 2 (Preparation of Ink Receptive Layer Coating Material) The silica fine particle dispersion prepared in Reference Example 1, the swelling clay compound dispersions (A) to (F) and the calcium carbonate dispersion (G) were mixed with silica. An ink receiving layer coating material was prepared by mixing the swelling clay compound with respect to the fine particles while stirring with a stirrer so that the solid content ratio was as shown in Table 5.

Examples 1 to 8 and Comparative Examples 1 to 6 100 μm, which is the support of the ink jet recording sheet.
m-thick transparent polyester film (D-
535, ICI Co., Ltd.) and 20 g in terms of solid content of each ink receiving layer coating material prepared in Reference Example 2 using a comma coater.
/ M ² was applied, the coated surface was cooled at 5 ° C for 60 seconds, and then dried at 100 ° C for 3 minutes to form an ink receiving layer, thereby preparing an inkjet recording sheet.

(Evaluation of Inkjet Recording Sheet) Regarding the obtained inkjet recording sheet, the "glossiness" of the surface, the degree of "cracking" at the time of formation of the ink receiving layer, and the "ink" are described as follows. Absorbency "was tested and evaluated. The results obtained are shown in Table 5.

Glossiness The ink jet recording sheet was visually observed from the direction of an elevation angle of 60 degrees, and the glossiness was evaluated according to the following criteria.

[0059] Rank criteria ◎: When gloss is particularly high ○: When gloss is high B: When gloss is slightly inferior, but practically no problem ×: When the gloss is extremely poor

Cracking The ink receiving layer of the ink jet recording sheet was visually observed and the degree of cracking was evaluated according to the following criteria.

Rank Criteria ⊚: No cracks are observed in the ink receiving layer ○: Very slight cracks in part of the ink receiving layer Δ: Part of the ink receiving layer has cracks, but practically When there is no problem x: When there is a strong crack on the entire surface of the ink receiving layer

Ink Absorption The ink-jet recording sheet PM manufactured by Seiko Epson Co., Ltd. is used for the ink receiving layer of the ink jet recording sheet.
Solid printing was performed using genuine ink at -800C, and immediately after printing, the printed portion was touched with a finger to visually observe whether the ink adhered to the finger, and the ink absorbency was evaluated according to the following criteria. .

[0063] Rank criteria ○: When ink does not adhere to the finger Δ: A little adhered, but practically no problem ×: When a large amount is attached

[0064]

[Table 5] Secondary particles 100 parts by weight of silica fine particles Swelling viscosity relative to average particle size of dispersion Example of ink type (μm) Amount of soil compound (part) Gloss Crack Absorption 1 A 95 1 △ △ ○ 2 A 95 5 ○ ○ ○ 3 A 95 10 ○ ◎ ○ 4 A 95 25 ◎ ◎ ◎ ○ 5 A 95 35 ◎ ◎ △ 6 B 260 5 △ △ ○ 7 D 110 10 ◎ ◎ ○ 8 E 185 10 ◎ ◎ ○ Comparative Example 1 A 95 50 ◎ ◎ × 2 − − 0 × × ○ 3 A 95 0.5 Δ × ○ 4 C 320 5 × × ○ 5 F 310 10 ○ × ○ 6 G 820 10 × × ×

From the results shown in Table 5, the swelling clay compound having an average secondary particle diameter of 300 nm or less was added to the silica fine particle dispersion in an amount of 1 to 3 with respect to 100 parts by weight of the silica fine particles.
The ink jet recording sheets of Examples 1 to 8 added in an amount of 5 parts by weight exhibited ink absorbency and glossiness above a level at which there was no practical problem, and inks below a level at which there was no practical problem. It can be seen that cracking of the receiving layer is suppressed.

On the other hand, in the case of the ink jet recording sheet of Comparative Example 1, since the swelling clay compound was too much,
There is no problem in glossiness and cracking, but the ink absorbency is insufficient, and in the case of the inkjet recording sheet of Comparative Example 2, the swelling clay compound was not added, and In the case of the inkjet recording sheet, it can be understood that both of them have a problem in terms of cracking because the blending amount is insufficient.

Further, in the case of the ink jet recording sheets of Comparative Example 4 and Comparative Example 5, a sufficient swelling viscosity compound was added, but the average particle size of the secondary particles was too large to disperse the particles. It is understood that both of them have a problem in terms of cracking in particular, since the properties are deteriorated. In the case of the ink jet recording sheet of Comparative Example 6, since the inorganic substances other than the swelling sticky compound are added, it is understood that all the evaluations are insufficient.

[0068]

EFFECT OF THE INVENTION According to the ink jet recording sheet of the present invention, while maintaining excellent ink absorbency, it is possible to have excellent glossiness and to prevent cracks during coating and drying when forming the ink receiving layer.

Claims (7)

[Claims] 1. An ink jet recording sheet having an ink receiving layer containing silica fine particles formed on at least one side of a substrate sheet, wherein the average particle diameter of primary particles of the silica fine particles is 30 nm or less, and An ink jet recording sheet, wherein the layer contains a swelling clay compound having an average secondary particle size of 300 nm or less as an inorganic binder. 2. The ink jet recording sheet according to claim 1, wherein the compounding amount of the swelling clay compound is in the range of 1 to 35 parts by weight with respect to 100 parts by weight of the silica fine particles. 3. The ink jet recording sheet according to claim 2, wherein the swelling clay compound is a layered inorganic polymer having an ion exchange ability. 4. The ink jet recording sheet according to claim 3, wherein the layered inorganic polymer is a hydrotalcite group mineral. 5. The ink jet recording sheet according to claim 3, wherein the layered inorganic polymer is a smectite group clay mineral. 6. The ink jet recording sheet according to claim 1, wherein the silica fine particles are synthesized by a gas phase method. 7. The silica fine particles 100 are used as the ink receiving layer.
The binder resin is contained in an amount of 10 to 40 parts by weight based on parts by weight, and the binder resin contains a partially saponified polyvinyl alcohol having an average degree of polymerization of 1700 to 3500 and a degree of saponification of 85 to 95 mol%. An ink jet recording sheet as described in Crab.