JP2002103792A - Ink jet recording sheet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording sheet for an ink jet printer having gloss of a photographic printing sheet style, excellent ink absorbing speed and ink absorbing amount. SOLUTION: An ink jet recording sheet comprises at least one porous ink acceptive layer on a base. In this case, the sheet comprises at least one porous ink acceptive layer having two peaks in a range of 6 to 100 nm of a pore size of 6 to 100 nm of a pore distribution curve measured by a mercury porosimeter for the acceptive layer.

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 and a method for producing the same, and more particularly, to an ink jet recording sheet.
The present invention relates to an ink jet recording sheet having a photographic photographic paper gloss and having both a high ink absorption speed and an ink absorption amount, and a method for manufacturing the same.

[0002]

2. Description of the Related Art An ink jet recording system is a recording system suitable for personal use because color printing can be performed at a low cost with a simple apparatus. In recent years, full color and high resolution have been achieved, and the ink jet recording system has rapidly spread. . Since the ink used in the ink jet system contains a large amount of solvent, it is necessary to discharge a large amount of ink in order to obtain a high print density. Therefore, as the ink receiving layer provided on the ink jet recording sheet, a material capable of sufficiently absorbing the ejected ink is required. Further, since the ink droplets are ejected continuously, if the next droplet is ejected before the first droplet is absorbed, it causes bleeding or uneven density, and a clear image cannot be obtained. Therefore, the ink receiving layer is required to have a high absorption rate as well as the absorption amount. Further, in addition to the above requirements for image quality, various performances such as ink drying properties, water resistance of printed matter, and image storage stability when stored for a long period of time are required.

In order to satisfy the above requirements, many ink jet recording sheets provided with a resin or pigment ink receiving layer have been proposed and are commercially available. The resin-based receiving layer is generally formed by applying an aqueous solution of a water-soluble resin such as polyvinyl alcohol, polyvinylpyrrolidone, a water-soluble cellulose derivative, or gelatin to a base sheet and drying. In the resin-based receiving layer, the discharged ink is absorbed by the dissolution and swelling of the receiving layer, so that there is an advantage that the ink absorption amount per unit weight of the receiving layer is large. In addition, there is an advantage that the printing density is high and the gloss is high because of high transparency. However, there are disadvantages that the image quality is poor due to the low ink absorption speed, and the ink drying speed is low and the water resistance is also poor.

[0004] The pigment-based receiving layer is formed by adding a water-soluble resin such as polyvinyl alcohol or a cellulose derivative as a binder resin to a pigment such as silica, alumina, pseudoboehmite, calcium carbonate or kaolin. In the pigment-based receiving layer, the ink is quickly absorbed into the pores formed by the pigment particles by capillary action to form an image, so that the image quality is good and the ink drying property is good. However, the ink receiving layer must have a sufficient pore volume to absorb a large amount of ink to be ejected, and requires a large amount of coating.

In JP-B-63-22977, the peak of the pore distribution curve of the uppermost ink receiving layer is 0.2 to 1
There is proposed an ink receiving layer which is located at 0 μm and has two peaks of a pore distribution curve of the entire ink receiving layer at 0.2 to 10 μm and 0.05 μm or less. Here, a high absorption rate and high image quality are obtained by taking the ink instantly absorbed into the large gaps in the uppermost layer into the gaps having a pore diameter of 0.05 μm or less. However, to obtain a receiving layer having such a pore distribution, it is necessary to use a pigment having a large secondary particle diameter. When such a pigment is used, the light transmittance is hindered, the receiving layer becomes opaque, and not only the print density is lowered, but also the gloss is low due to the decrease in surface smoothness, which is required in recent inkjet printing. , High gloss photo quality could not be obtained.

Japanese Patent Application Laid-Open No. 9-183267 proposes an ink receiving layer in which the uppermost layer contains colloidal silica and the pore distribution curve has a peak in the range of pore diameter of 2 to 100 nm. When a pore peak is present in this range, the ink absorption speed is increased, and since colloidal silica is used, the gloss is excellent and the transparency is good. However, there is a drawback that the receiving layer has a low pore volume and two receiving layers must be provided in order to absorb a large amount of ink.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, and to provide an ink jet printer having a photographic paper-like gloss and an excellent ink absorption speed and ink absorption amount. An object of the present invention is to provide a recording sheet for a printer.

[0008]

In the pore distribution curve obtained by the measurement with a mercury porosimeter, the pore diameter is 6 to 100.
In general, a porous ink receiving layer having a peak in the range of nm can quickly absorb the ink by virtue of its strong capillary force to obtain a clear image. However, in recent years, high-quality images have been required for ink-jet printing,
Accordingly, the ink ejection amount has also increased. In the case of a porous receiving layer having a pore diameter in the above range and having only one peak as shown in FIG. 2, the ink absorption amount may be insufficient to absorb a large amount of ejected ink instantaneously. In many cases, there is a tendency that ink overflows and print density unevenness called beading occurs. The present inventors have made intensive studies and found that the ink receiving layer having two peaks in the range of pore diameter of 6 to 100 nm as shown in FIG. 1 has a high ink absorption rate and instantaneously absorbs a large amount of ink. Have been found possible, and the present invention has been completed.

That is, the first invention of the present invention relates to an ink jet recording sheet having at least one porous ink receiving layer provided on a substrate, wherein a pore distribution curve of the same layer measured by a mercury porosimeter is used. Pore size 6-100
an ink jet recording sheet having at least one porous ink receiving layer having two peaks in the range of nm.

[0010] The second invention is "the ink jet recording sheet according to the first invention, characterized in that, of the two peaks, the peak with the larger intensity is in the range of pore diameter of 10 to 25 nm." is there.

[0011] The third invention is based on the invention that the pore volume of a layer having two peaks in the porous ink receiving layer has a pore diameter of 6 to 20;
0-1.5 ml / g in the range of 0 nm
Or the inkjet recording sheet according to the second invention "
It is.

[0014] A fourth invention is the "ink-jet recording sheet according to any one of the first to third inventions, wherein the base material is a synthetic resin film or a synthetic resin laminated paper".

According to a fifth aspect of the present invention, a layer having two peaks among the porous ink receiving layer has an average particle diameter of 1 μm or less and a pore volume in a range of 6 to 200 nm of 0.4 to 2.
The inkjet recording sheet according to any one of the first to fourth inventions, wherein the inkjet recording sheet comprises 5 ml / g of a fine pigment and a binder resin.

According to a sixth aspect of the present invention, there is provided a water-based paint comprising a porous ink receiving layer containing a fine pigment and a binder resin, and containing the binder resin in a proportion of 3 to 28 parts by weight based on 100 parts by weight of the fine pigment. Coating the coating material, then irradiating the coating layer with an electron beam to hydrogel the coating layer, followed by drying to form a porous ink receiving layer.
The method for producing an ink jet recording sheet according to any one of the inventions described above.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, measurement of pore distribution using a mercury porosimeter will be described. The pore distribution is Micrometrics Pore Sizer 9320 (manufactured by Shimadzu Corporation)
And the pore distribution was calculated from the void volume distribution curve obtained by the mercury intrusion method. The measurement of the pore diameter by the mercury intrusion method was calculated using the following equation derived assuming that the cross section of the pore was circular.

D = -4γCOS θ / P where D: pore diameter, γ: surface tension of mercury, θ: contact angle, P: pressure.

The surface tension of mercury is 482.536 dyn /
cm, the contact angle used was 130 °, and the high pressure part measurement (0
３０30000 psia, measured pore size 6 μm to 6 nm). The average pore volume of the ink receiving layer is calculated from a previously measured weight of the ink receiving layer and a void volume distribution curve. In the pore distribution curve of the ink receiving layer in the present invention,
Since it has a peak in the range of 6 to 100 nm and the base of the peak extends to 200 nm, the pore volume in the range of 6 to 200 nm was integrated and determined.

Next, the ink receiving layer of the present invention will be described. The porous ink receiving layer in the present invention has a pore distribution curve obtained by the measurement using the mercury porosimeter,
As shown in FIG. 1, it has two peaks in the range of pore diameter of 6 to 100 nm. An example having two peaks in this range is also described in the example of JP-A-9-183267. However, when two ink receiving layers are provided, one is provided in each of the receiving layers. This is the appearance of peaks that are present each time. On the other hand, in the porous ink receiving layer according to the invention, the pore size of at least one of the receiving layers is 6 to 1.
JP-A-9-183 has two peaks in the range of 00 nm and two peaks in one receiving layer.
267 is different from the invention. When the peak of the pore diameter exists only in a range of less than 6 nm, a sufficient ink absorption rate cannot be obtained, and uneven printing density called ink overflow or beading occurs. The peak of the pore diameter is 100 nm.
In the receiving layer existing only in the range exceeding the range, the ink tends to spread, and a clear image cannot be obtained. Further, the transparency is lowered, the print density is lowered, and the glossiness is lost.

In the porous ink receiving layer of the present invention, it is preferable that, of the two peaks having a pore diameter in the range of 6 to 100 nm, the peak having the larger intensity is in the range of 10 to 25 nm. The pores in this range have a strong capillary force, so that the ejected ink can be instantaneously absorbed. Further, if there is another pore peak in the range of pore diameter of 6 to 100 nm, the pore volume contributing to ink absorption increases,
A large amount of ink once absorbed by the pores in the range of 5 nm can be immediately taken in, and the ink can be absorbed without overflow even if the ink is successively ejected.

The pore volume of the ink receiving layer measured by the above method in the range of pore diameter of 6 to 200 nm is 0.5.
It is preferably 1.5 ml / g. Pore size 6-2
If the pore volume of 00 nm is smaller than 0.5 ml / g, a large amount of ink to be ejected cannot be sufficiently absorbed unless the coating amount of the ink receiving layer is significantly increased, and the image is disturbed by ink overflow. There is fear. On the other hand, the pore diameter 6
If the pore volume of ~ 200 nm is larger than 1.5 ml / g, the fixability of the dye may be reduced or the strength of the ink receiving layer may be reduced.

Hereinafter, the method for forming the ink receiving layer of the present invention will be described. The ink receiving layer of the present invention is manufactured by solidifying a pigment with a binder resin. The pigments used include silica, aluminosilicate, kaolin, clay, calcined clay, zinc oxide, tin oxide, aluminum hydroxide, boehmite, pseudoboehmite, alumina, calcium carbonate, satin white, aluminum silicate, smectite, magnesium silicate, and carbonic acid. Various pigments known in the field of general coated paper or ink jet recording paper, such as magnesium, magnesium oxide, diatomaceous earth, styrene-based plastic pigment, urea resin-based plastic pigment, benzoguanamine-based plastic pigment, and the like, but are not limited thereto. is not. Among these pigments, silica, aluminum hydroxide, boehmite, pseudoboehmite, and alumina are particularly preferably used because of their large pore volume and excellent ink absorbability.

As a form of the pigment, a fine pigment having an average particle diameter of 1 μm or less is preferable in order to obtain an ink receiving layer having high gloss and high transparency. Further, it is preferable that the fine pigment is a secondary particle composed of primary particles having an average primary particle diameter of 5 to 100 nm, preferably 6 to 40 nm, since the pore volume is high.
The average particle size of the secondary particles obtained by aggregating these primary particles is 1 μm.
Hereinafter, preferably 9 to 800 nm, more preferably 10 to 800 nm.
６００600 nm, most preferably 15-400 nm. If the primary particle diameter or the secondary particle diameter of the pigment is too small, it is difficult to form voids contributing to ink absorption, and there is a possibility that the pore volume of the receiving layer is reduced and the ink absorbency is reduced. On the other hand, if the primary particle diameter or the secondary particle diameter is too large, the transparency of the receiving layer is reduced, and the print density and gloss may be reduced.
The primary particle size of the pigment referred to in the present invention is all the particle size (Martin size) observed with an electron microscope (SEM and TEM).
It is. The secondary particle diameter is a value measured by the dynamic light scattering method and calculated from analysis using the cumulant method.

In order to obtain an ink-receiving layer having a high ink absorption capacity, it is preferable that the fine pigment has a high pore volume, but the fine pigment preferably used in the present invention has a fine pore volume (pore diameter of 6 to 200 nm). Is preferably 0.4 to 2.5 ml / g, more preferably 0.6 to 2.0 ml / g, and particularly preferably 0.7 to 1.8 ml / g. The pore volume is a value measured with a mercury porosimeter.

The method for producing these fine pigments is not particularly limited, but one of the means is to pulverize and disperse a commercially available pigment (having a particle size of several μm) by applying a strong force by mechanical means. There is a method of obtaining. That is, bre
aking down method (method of breaking up bulk raw materials)
Is obtained by Examples of the mechanical means include mechanical methods such as an ultrasonic homogenizer, a pressure homogenizer, a nanomizer, a high-speed rotation mill, a roller mill, a container driving medium mill, a medium stirring mill, a jet mill, and a sand grinder. The obtained fine pigment may be in the form of a colloid or a slurry. As another preferred method for producing a fine pigment, JP-A-5-32
413 and JP-A-7-76161.

As the binder resin, a water-dispersible resin and a water-soluble polymer can be used, but a water-soluble polymer is preferable.
Examples of the water-soluble polymer include polyvinyl alcohol, polyethylene oxide, polyalkylene oxide, polyvinylpyrrolidone, water-soluble polyvinyl acetal, poly-N-vinylacetamide, polyacrylamide, polyacryloylmorpholine, polyhydroxyalkyl acrylate, polyacrylic acid, Hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, gelatin,
And casein and their water-soluble derivatives. Further, a copolymer containing each of the above resins or a water-soluble derivative may be used. In addition to using these resins alone,
Two or more kinds can be used as a mixture.

In addition to the main components such as the pigment and the binder resin, various additives are used according to the purpose. For example, a cationic resin as an ink fixing agent can be used. Examples of the cationic resin include N, N-dimethylaminoethyl acrylate quaternary, N, N-dimethylaminoethyl methacrylate quaternary, N, N-dimethylaminopropylacrylamide quaternary, vinyl imidazolium methochloride, Resins containing cationic structural units such as diallyldimethylammonium chloride, monoallylamine hydrochloride, diallylamine hydrochloride and the like are included. When these cationic resins are mixed and added to a dispersion of an anionic pigment such as silica, the paint temporarily gels due to the electrostatic properties of both, but is redispersed using mechanical means such as a homogenizer. By doing so, it can be used. It is also possible to mix an inorganic salt, alumina sol, or the like as the cationic substance. Other additives, such as dispersants, thickeners, defoamers, coloring agents, antistatic agents, wetting agents, etc. used in the production of general coated paper, and for improving the storage stability of printed images UV absorbers and light stabilizers can be appropriately added.

The method for forming the above-mentioned pigment-based receiving layer is not particularly limited.
The following method is preferably used to obtain a receiving layer having two peaks in the range of 100 nm to 100 nm. The above pigment 10
1 to 100 parts by weight, preferably 3 to 28 parts by weight, more preferably 5 to 5 parts by weight of the binder resin, based on 0 parts by weight.
Applying an aqueous paint containing 20 parts by weight to a substrate,
Then, the coating layer is irradiated with an electron beam to hydrogel, and then dried to form a receptor layer. The preferred pigment in the present invention is a fine pigment having a small particle size, but when coating a paint containing the fine pigment, film formation failure due to cracking is likely to occur due to strong capillary force generated upon drying after coating. . However, in the method using an electron beam as described above, since cracks can be prevented, the amount of binder resin mixed with the pigment can be reduced. Therefore, many voids can be provided in the receiving layer, and a receiving layer having two peaks in the range of pore diameter of 6 to 100 nm as in the present invention can be easily obtained. By drying after the coating film is gelled once by an electron beam, drying shrinkage is suppressed as compared with the case of only normal drying, so it is considered that relatively large voids between secondary particles are also generated in the coating film. . The hydrogel is a polymer having a three-dimensional network structure in a state of being swollen with a solvent containing water as a main component, and refers to a state of no fluidity.

As an electron beam irradiation method, for example, a scanning method, a curtain beam method, a broad beam method, or the like is employed. The acceleration voltage when irradiating the electron beam is 1
About 100 to 300 kV is appropriate. The irradiation amount of the electron beam is preferably adjusted in a range of about 0.1 to 20 Mrad. If it is less than 0.1 Mrad, it will not cure sufficiently,
Irradiation exceeding d is not preferable because it may deteriorate the base material.

As the substrate sheet in the present invention, a synthetic resin film of polyethylene terephthalate, polyvinyl chloride, polycarbonate, polyimide, cellulose triacetate, cellulose diacetate, polyethylene, polypropylene or the like, or a synthetic resin laminate paper such as polyethylene laminate paper is used. It is preferable because it is easy to obtain an ink jet recording sheet having a high gloss and is suitably used depending on the purpose.

When the adhesion to the ink-receiving layer formed on the surface of these substrates is insufficient, an undercoat layer can be applied or various easy adhesion treatments such as corona discharge treatment can be applied. The thickness of the substrate is preferably 50 to 500 μm in consideration of the paper passing property of the printer.

As the coating method, known coating means such as a bar coating method, a roll coating method, a blade coating method, an air knife coating method, a gravure coating method, a die coating method and a curtain coating method can be used. This is not the case.

The coating amount is 1 to 50 g / dry weight.
m ² is preferable, and more preferably 3 to 25 g / m ^2.
It is. Here, if the amount is less than 1 g / m ² , the ink absorption tends to be insufficient, and if the amount is more than 50 g / m ² , curling is likely to occur and the cost is increased, which is not preferable.

A back layer may be provided on the side opposite to the ink receiving layer of the base sheet in order to suppress the curl of the ink jet recording sheet and improve the transportability. The configuration of the back surface layer and the accompanying easy adhesion treatment of the back surface of the base sheet can be selected according to the application, and are not particularly limited. However, in view of coating properties and costs, hydrophilic resins are mainly used. It is preferable to provide a back layer as a component. In the present invention, sufficient ink absorptivity can be obtained even if only one porous ink receiving layer is used, but two or more layers can be provided. For example, an undercoat layer containing the pigment and the resin binder can be provided.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Parts and percentages are by weight unless otherwise specified.
Indicate weight%.

[Method of Measuring Pore Volume of Pigment] The aqueous dispersion of the pigment was dried at 105 ° C., and the pore volume of the obtained powder sample was measured using a Micrometrics pore sizer 9320 (manufactured by Shimadzu Corporation). It was determined by integrating the pore volumes in the range of 6 to 200 nm.

[Determination of Average Particle Size of Pigment] Laser particle size analyzer by dynamic light scattering method (LPA3000, manufactured by Otsuka Electronics Co., Ltd.)
/ 3100) was measured in a state where the aqueous dispersion of the pigment was sufficiently diluted with distilled water. The average particle size used was a value calculated from analysis using the cumulant method.

[Method for Producing Silica Sol A (Dispersion)] Silica having an average primary particle diameter of 7 nm (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL30) produced by a gas phase method
0) was dispersed in a hydraulic ultrahigh-pressure homogenizer (Microfluidizer M11, manufactured by Mizuho Industry Co., Ltd.).
(0-E / H) three times. The pore volume of the fine silica was 1.2 ml / g. 10 parts of an 11% aqueous solution of diallyldimethylammonium chloride / acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) was added to 100 parts of the dispersion as an ink fixing agent, and the mixture was gelled. Was further dispersed in the same homogenizer to produce an aqueous silica dispersion having an average secondary particle diameter of 100 nm. This dispersion had a solids concentration of 11%, a silica concentration of 10%, and a diallyldimethylammonium chloride / acrylamide copolymer concentration of 1%.
The pore volume of this silica fine pigment was 1.0 ml / g.

[Production Method of Silica Sol B (Dispersion)] Synthetic amorphous silica having an average particle size of 7.5 μm produced by a gel method (trade name: Silojet P612, manufactured by Grace Devison, specific surface area: 287 m ² / g) ) Was pulverized and dispersed by a sand grinder, and further repeatedly pulverized and dispersed by a hydraulic ultra-high pressure homogenizer used in the method for producing silica sol A, to obtain silica 20 having an average secondary particle diameter of 300 nm.
% Aqueous dispersion was prepared. The pore volume of this silica fine pigment was 0.5 ml / g.

<Example 1> 15 parts of a 10% aqueous solution of partially saponified polyvinyl alcohol (Kuraray Co., Ltd., trade name: PVA-235) was mixed with 100 parts of silica sol A,
A paint having a solid content concentration of 10.9% containing 15 parts of polyvinyl alcohol with respect to 100 parts of silica was prepared. This coating material was coated on a transparent polyethylene terephthalate film having a thickness of 100 μm as a base material (trade name: Lumirror 100-Q80D, manufactured by Toray Industries, Inc.) at a coating weight of 25 g / dry weight.
Bar coating was performed so as to obtain m ² . This was immediately irradiated with an electron beam having an acceleration voltage of 175 kV and an irradiation dose of 5 Mrad by an electron beam irradiation apparatus (Electron Curtain manufactured by ESI). After irradiation, the hydrogel film was dried at 100 ° C. to obtain an ink jet recording sheet of the present invention. Table 1 shows the method for forming the ink receiving layer of the ink jet recording sheet. Further, the pore distribution and the image quality of the ink receiving layer in this ink jet recording sheet were evaluated by the following methods, and are shown in Table 2.

[Measurement of Pore Distribution of Ink Receiving Layer] The pore distribution of the ink receiving layer in the ink jet recording sheets of Examples and Comparative Examples of the present invention was measured as follows. Micrometrics pore sizer 9320
Using (manufactured by Shimadzu Corporation), the pore position was calculated from the pore volume distribution curve obtained by the mercury intrusion method, and the peak position was obtained. Further, from the obtained pore distribution curve, 6 to
It was determined by integrating the pore volume in the range of 200 nm. In the receiving layer of each of Examples and Comparative Examples, the pore diameter is 6 to 100 n.
m, the number of peaks, the peak positions and the pore diameters of 6 to 20
Table 1 shows the pore volumes in the range of 0 nm.

Evaluation method of image quality of ink jet recording sheet [Ink absorption speed] The ink absorption speed of the ink receiving layer in the present invention was evaluated by the following method. Inkjet printer (EPSON,
In the recommended print mode for super fine paper of PM-800C), solid colors of cyan, magenta, yellow and black were printed. The PPC paper was pressed against the printing portion by hand, and whether or not the ink was transferred was visually inspected. The time until transfer disappeared was measured and evaluated in the following three steps. : Less than 1 second: 1 second or more and less than 30 seconds ×: 30 seconds or more

[Ink Absorption Amount] The ink absorption amount of the ink receiving layer in the present invention was evaluated by the following method. A mixed color of red, green, and blue was printed on the ink jet recording sheet by the above method, and the presence or absence of ink overflow and the uniformity of print density were evaluated on the following three scales. : No ink overflow and good uniformity. : No ink overflow, but poor density uniformity. ×: Overflow of ink is observed.

<Example 2> 10% of the partially saponified polyvinyl alcohol used in Example 1 was added to 100 parts of silica sol A.
The present invention was carried out in the same manner as in Example 1 except that a paint having a solid content concentration of 10.8% containing 20 parts of polyvinyl alcohol with respect to 100 parts of silica, prepared by mixing 20 parts of an aqueous solution, was used. An ink jet recording sheet was obtained. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Example 3 100 parts of silica sol prepared by mixing 30 parts of a 5% aqueous solution of completely saponified polyvinyl alcohol (Kuraray Co., Ltd., trade name: PVA-140H) with 100 parts of silica sol A was used. An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1, except that a paint having a solid content of 9.6% containing 15 parts of polyvinyl alcohol was used. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

<Example 4> 10% of the partially saponified polyvinyl alcohol used in Example 1 was added to 100 parts of silica sol B.
The present invention was carried out in the same manner as in Example 1 except that a paint having a solid content concentration of 17.7% containing 15 parts of polyvinyl alcohol with respect to 100 parts of silica, prepared by mixing 30 parts of an aqueous solution, was used. An ink jet recording sheet was obtained. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Example 5 An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that a polyethylene-based synthetic resin laminated paper was used as the base material. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

<Comparative Example 1> 10 parts of the partially saponified polyvinyl alcohol used in Example 1 was added to 100 parts of silica sol A.
An ink jet recording sheet was prepared in the same manner as in Example 1 except that a paint having a solid content of 10.8% containing 30 parts of polyvinyl alcohol with respect to 100 parts of silica was prepared by mixing 30 parts of an aqueous solution. I got Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Comparative Example 2 A solid prepared by mixing 60 parts of a 5% aqueous solution of the fully saponified polyvinyl alcohol used in Example 3 with 100 parts of silica sol A, containing 30 parts of polyvinyl alcohol per 100 parts of silica An ink jet recording sheet was obtained in the same manner as in Example 1 except that a paint having a concentration of 8.8% was used. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Comparative Example 3 The coating material used in Comparative Example 2 was bar-coated on the transparent polyethylene terephthalate film used in Example 1 so that the coating amount was 25 g / m ² by dry weight. It dried at ° C and obtained the ink jet recording sheet. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Comparative Example 4 An ink jet recording sheet was obtained in the same manner as in Comparative Example 3 except that the paint used in Example 4 was used. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Comparative Example 5 A 20% aqueous dispersion of cationic silica having an average secondary particle size of 300 nm, silica sol C
(Product name: Silo Jet 703, manufactured by Grace Devison)
C, pore volume 0.63 ml / g, specific surface area 224 m ² /
g) 100 parts of a 5% aqueous solution of fully saponified polyvinyl alcohol used in Example 3 was mixed with 120 parts of 100 parts of silica.
An ink jet recording sheet was obtained in the same manner as in Comparative Example 3 except that a paint having a solid concentration of 11.8% contained in 0 part was used. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

Comparative Example 6 An ink jet recording sheet was obtained in the same manner as in Comparative Example 1, except that a polyethylene-based synthetic resin laminated paper was used as the base material. Table 1 shows the method of forming the ink receiving layer, and Table 2 shows the measurement results of the pore distribution and the image quality evaluation results.

[0053]

[Table 1]

[0054]

[Table 2]

As is clear from the examples in Table 2, the ink jet recording sheet having the ink receiving layer having two peaks in the range of the pore diameter of 6 to 100 nm has a sufficiently high ink absorption rate and has two peaks. Therefore, the pore volume is large and the ink absorption amount is also large. In particular, in Examples 1 and 5, even though silica having a pore volume of 1.0 ml / g was used, the pore volume of the ink receiving layer was 1.22 ml / g, which was larger than that. Also in Example 4, the pore volume of the ink receiving layer using silica having a pore volume of 0.5 ml / g was 0.77 ml / g. In addition, Examples 1 to
The peak with the larger intensity among the two peaks of No. 5 had the smaller pore diameter, and was in the range of the pore diameter of 10 to 25 nm. On the other hand, in the ink jet recording sheet having only one peak in the above-mentioned pore diameter range as in each comparative example, the ink absorption rate was low and the pore volume was difficult to increase, so that the ink absorption amount was insufficient.

[0056]

By providing the ink receiving layer with two peaks in the pore diameter range of 6 to 100 nm, an ink jet recording sheet having a high ink absorption rate and high ink absorption amount can be obtained. The ink jet recording sheet of the present invention has both ink absorbency, glossiness and ink drying property.

[Brief description of the drawings]

FIG. 1 is a diagram of a pore distribution curve of an ink receiving layer in an ink jet recording sheet of the present invention. V indicates the pore volume of the ink receiving layer, and D indicates the pore diameter of the ink receiving layer.

FIG. 2 is a diagram of a pore distribution curve of an ink receiving layer having only one peak in a range of pore diameter of 6 to 100 nm.

Claims (6)

[Claims] 1. An ink jet recording sheet having at least one porous ink receiving layer provided on a base material, wherein a pore distribution curve measured by a mercury porosimeter for the same layer has two pore diameters in a range of 6 to 100 nm. An ink jet recording sheet having at least one porous ink receiving layer having a peak. 2. The ink jet recording sheet according to claim 1, wherein a peak having a higher intensity among the two peaks is in a range of a pore diameter of 10 to 25 nm. 3. The porous ink receiving layer according to claim 1, wherein the layer having two peaks has a pore volume of 0.5 to 1.5 ml / g in a pore diameter of 6 to 200 nm. Inkjet recording sheet. 4. The ink jet recording sheet according to claim 1, wherein the substrate is a synthetic resin film or a synthetic resin laminated paper. 5. A layer having two peaks in the porous ink receiving layer is one having an average particle diameter of 1 μm or less and a pore diameter of 6 to 20.
The ink jet recording sheet according to any one of claims 1 to 4, comprising a fine pigment having a pore volume of 0.4 to 2.5 ml / g in a range of 0 nm and a binder resin. 6. A porous ink receiving layer containing a fine pigment and a binder resin, and an aqueous paint containing a binder resin in a ratio of 3 to 28 parts by weight with respect to 100 parts by weight of the fine pigment is applied to a substrate, The method for producing an ink jet recording sheet according to any one of claims 1 to 5, wherein the coating layer is hydrogelled by irradiation with an electron beam and then dried to form a porous ink receiving layer. Method.