JPH10193777A - Inkjet recording material - Google Patents

Abstract

(57) [Problem] To provide an ink-jet recording material capable of rapidly absorbing ink and having good ink absorbability and obtaining a printed image without bleeding or overflow, containing an alumina hydrate. An object of the present invention is to provide an ink jet recording material free of cracks in a coating film of an ink absorbing layer when a liquid is applied on a support to form an ink absorbing layer. In an inkjet recording material comprising an alumina hydrate and a water-soluble binder, the alumina hydrate has an average aspect ratio of 3 to 7 and a pore radius of 2 nm or more.
Alumina hydrate having a plate-like pseudo-boehmite structure having a pore volume of 0.1 ml / g or more in a range of nm or less, a polymerization degree of 2000 or more as a water-soluble binder, and a saponification degree of 88% or more 1
By using less than 00% of polyvinyl alcohol and further adding at least one kind selected from boric acid or borate to the ink absorbing layer, an ink absorbing layer in which cracks are suppressed is provided on the support. did it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material used for a printer or a plotter using an ink jet recording system, and has no crack in a coating film which can be used as a film for an OHP (overhead projector). It relates to a recording material having high transparency.

[0002]

2. Description of the Related Art In recent years, remarkable progress in ink jet printers and plotters has made it possible to easily obtain full-color and high-definition images. Along with this, there has been a keen demand for development of ink jet recording materials other than conventional high quality paper for ink jet recording and coated paper.

In the ink jet recording system, fine droplets of ink are made to fly by various operating principles and adhere to a recording material such as paper to record images and characters.
Inkjet printers and plotters have the features of being excellent in high-speed printing and low noise, having great flexibility in recording patterns, and requiring no development-fixing, and are capable of forming complex images accurately and quickly. It is attracting attention. In particular, as an apparatus for creating a hard copy of image information such as characters and various figures created by a computer, it is rapidly spreading in recent years in various applications. Further, by using a plurality of ink nozzles, it is easy to perform multicolor recording. The color image formed by the multi-color ink jet method can obtain a record comparable to the multi-color printing by the plate making method and the printing by the color photographic method, and in applications where the number of copies is small, It is being widely applied because it is less expensive than printing and photographic techniques.

In recent years, ink jet printers and the like which can output a high-definition image comparable to a silver halide photograph image have been commercially available at low cost. The recording material for inkjet is
Compared to the silver halide photography method, it is very inexpensive while obtaining images of the same quality, so it is economically large for users who frequently change display images on illuminated signs and product samples that require large area images. There are benefits. Also, create images on personal computers that have become popular recently,
While it was impossible to print out and correct the color scheme and layout while looking at it, the conventional silver halide photography method was completely impossible, but ink jet recording has the advantage that such operations can be easily performed.

[0005] As fields of application of ink jet printers and plotters, attention has recently been paid particularly to the production of color printing plates in the printing field where image quality close to a photograph is required and the output of design images in the design department. Full-color image recording or the like, or image information created by a computer is recorded on a transparent recording material by an ink-jet printer, and is used by an OHP at a conference presentation or the like.

[0006] With the above-mentioned demands from the field of application of ink jet printers and plotters and the spread of ink jet printers and plotters, demands for recording materials have diversified, and for example, they have a glossy surface as high as silver halide color photographs. Recording material with excellent appearance aptitude, O
There is a demand for highly transparent recording materials that can be used as HP films.

As the recording material used in the ink jet recording system, efforts have been made in terms of the apparatus and ink composition so that high quality paper for writing or coated paper or coated paper can be used. However, with the improvement of the performance of ink jet recording apparatuses and recording methods such as high-speed recording and high-definition recording, or full-color recording, and expansion of applications, more advanced characteristics are required for recording materials. It has become That is, as the recording material, the density of the print dots is high, the color tone is bright and vivid, the ink absorption is fast, the ink does not flow or bleed even when the print dots overlap, Is required not to be unnecessarily large in the lateral direction, and to be smooth and unsharp in the periphery. In particular, in the case of color printing, not only single-color printing of yellow, magenta, cyan, and black, but also multi-color printing in which these colors are superimposed is performed, and extremely strict performance is required because the ink adhesion amount is further increased.

Conventional recording materials for ink jet recording are described in, for example, JP-A-55-51583 and JP-A-56-157.
Nos. 57-107879 and 57-107880
No. 59-230787, No. 62-160277
Nos. 62-184879 and 62-183382
No. 64-11877, etc., a recording material obtained by applying a silicon-containing pigment such as silica to a paper surface together with an aqueous binder has been proposed, but the silica and the like used in these examples have been proposed. Pigment particles have a large oil absorption,
Recording materials using these materials generally reach a certain level in terms of ink absorption capacity and absorption speed, but since it is necessary to introduce a large amount of an inorganic pigment such as silica into the coating layer, There is a disadvantage that the surface gloss of the recording material itself is reduced. It is not preferable to use colloidal silica in place of silica for the purpose of improving glossiness, as described in JP-A-56-157, because it deteriorates the ink absorbency.

As a recording material for an ink jet having a glossy surface, a cast coated paper obtained by performing a cast finish while the coating layer is in a wet state is disclosed in JP-A-6-32.
No. 0857, etc., the surface gloss is extremely low as compared with silver halide photographs, and the texture of silver halide photographs cannot be obtained.

On the other hand, as an ink jet recording material having improved transparency and gloss, a material having an ink absorbing layer made of a resin on a support has been proposed. Examples of resins used in such applications include, for example,
No. 38185, No. 62-184879, etc., polyvinylpyrrolidone, vinylpyrrolidone-
Vinyl acetate copolymer, a resin composition mainly containing polyvinyl alcohol as described in JP-A-60-168651, JP-A-60-171143 and JP-A-61-134290, JP-A-60-234879 Copolymers of vinyl alcohol and olefin or styrene and maleic anhydride shown in JP-A-61-74879, cross-linked products of polyethylene oxide and isocyanate shown in JP-A-61-74879, and JP-A-61-181679. A mixture of carboxymethyl cellulose and polyethylene oxide, a polymer obtained by grafting methacrylamide to polyvinyl alcohol shown in JP-A-61-132377, an acrylic polymer having a carboxyl group shown in JP-A-62-220383, JP-A-4-2143 Polyvinyl acetal polymer represented in 2 JP etc., JP 4-282282, the 4
Various ink-absorbing polymers such as a crosslinkable acrylic polymer as described in JP-A-285650 have been proposed. JP-A-4-282282, JP-A-4-285650 and the like propose a recording material in which a polymer matrix composed of a crosslinkable polymer is mixed with an absorbing polymer. The ink absorbing layer has a drawback that the absorption rate is lower than that of the ink absorbing layer made of fine particles of pigment such as silica.

As an ink-jet recording material having a high ink absorption rate and improved transparency and gloss, an ink-jet recording material using alumina hydrate has recently been proposed. No. 60-232990,
JP-A-60-245588, JP-B-3-24906, JP-A-2-276670, JP-A-3-215082
Nos. 4-37576, 4-67986, 5-
No. 16517, No. 5-24335, No. 5-32037
Nos. 5-50739, 5-286228, and 5
Nos. -301441, 6-48016 and 6-558
No. 29, No. 6-183126, No. 6-184954
Nos. 6-199034, 6-199035, 6-218324, 6-255235, 6-26
No. 2844, No. 6-270530, No. 6-28629
No. 7, No. 6-297831, No. 6-297832,
6-316145, 7-68919, 7-6
No. 8920, No. 7-76161, No. 7-76162
And JP-A-7-82694, JP-A-7-89221, and the like, disclose a recording material for inkjet recording in which a fine alumina sol is coated on a support surface together with a water-soluble binder. Both have ink absorption,
The present invention relates to improvements in resolution, image density, color, ink adsorbability, transparency, etc., wherein an ink has good ink absorptivity, and has an inorganic porous layer with good dye fixability. In order to obtain a recording material, as described in JP-A-5-24335, the ink absorbing capacity is not sufficient unless the coating amount is about 20 g / m ² or more, as described in JP-A-5-24335. The absorption capacity can be ensured by coating the film, but when the thick film is applied, cracks are very likely to occur in the ink absorbing layer during drying, and it is necessary to suppress the occurrence of cracks during drying.

As a method for suppressing cracks in a coating film during coating and drying of an ink absorbing layer composed of alumina hydrate, polyvinyl alcohol is used as a binder as described in JP-A-7-76161. There has been proposed a method of suppressing cracks by gelling polyvinyl alcohol as a binder with boric acid or a borate to improve the strength of a coating film. However,
In the case of alumina hydrate having poor film-forming properties, cracks cannot be suppressed unless the amount of boric acid or borate is increased, but if the amount of boric acid or borate is large, the viscosity of the coating liquid may be reduced. Cannot be avoided over time, and coating stability deteriorates. In addition, the gelled product causes coating streaks, which causes deterioration of surface quality, and further deteriorates ink absorbency. JP-A-6-218324 proposes a method in which a coating solution comprising alumina hydrate is applied onto a support, and ammonia gas is sprayed before removing the solvent to cause gelation. However, ammonia gas is not only highly corrosive but also explosive and dangerous. In addition, it is necessary to recover excess ammonia gas, which is not desirable in terms of simplicity of operation and equipment. As a method for solving the above-mentioned problems, Japanese Patent Application Laid-Open No. 7-89221 proposes a recording material for ink jet having an ink absorbing layer made of alumina hydrate and gelatin. This method utilizes the property that a gelatin solution dissolved in warm water gels at a low temperature. However, this method requires a special curtain coater that can be heated,
This is undesirable in terms of simplicity of operation and equipment, such as the necessity of a cooling zone for gelling gelatin before the drying zone for removing the solvent. In addition, if the drying temperature is increased, gelatinized gelatin is redissolved, so that it is necessary to reduce the coating speed at a low temperature and dry, which is not desirable from the viewpoint of productivity.

Further, Japanese Patent Application Laid-Open Nos. 7-232473 and 7-
JP-A Nos. 232474 and 7-232475 disclose a recording material for ink-jet recording using an alumina hydrate having a plate-like amorphous structure having an aspect ratio of 3 to 10. However, among these, an alumina hydrate having an amorphous structure having a smaller pore volume than an alumina hydrate having a pseudo-boehmite structure is used. This is not preferable because the ink absorption capacity decreases.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording material for ink jet which can rapidly absorb ink to obtain a printed image with good ink absorbency and without bleeding or overflow. is there. Another object of the present invention is to provide an ink-jet coating that is free from cracks in the ink-absorbing layer coating and dried when the coating liquid containing alumina hydrate is applied to the support to form the ink-absorbing layer. It is to provide a recording material.

[0015]

The object of the present invention is solved by the following means.

That is, in an ink-jet recording material having an ink-absorbing layer provided on a support, the ink-absorbing layer has an average aspect ratio of 3 to 7 and a pore radius of 2 nm to 10 nm.
By containing a hydrated alumina hydrate having a pseudo boehmite structure having a plate-like pore volume of 0.1 ml / g or more in a range of nm or less and polyvinyl alcohol, it is possible to more stably suppress the generation of microcracks. As a result, it was possible to provide an inkjet recording material having better ink absorbability.

In the recording material for ink jet recording, in which an ink absorbing layer is provided on a support, the alumina hydrate having a plate-like pseudo-boehmite structure has a degree of polymerization of 2,000 or more and a degree of saponification of 88% to less than 100%. By applying a coating liquid containing polyvinyl alcohol on a support and forming an ink absorbing layer, it was possible to provide an inkjet recording material in which the occurrence of microcracks during coating and drying was suppressed.

Further, in the present invention, the use of polyvinyl alcohol crosslinked by at least one selected from boric acid or borate as the polyvinyl alcohol suppresses the occurrence of microcracks during coating and drying. The recording material can be provided.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Alumina hydrate can be represented by the following general formula.

Al ₂ O ₃ .nH ₂ O In the formula, when n is 1, it represents an alumina hydrate having a boehmite structure, and when n is more than 1 and less than 3, a alumina hydrate having a pseudo-boehmite structure Where n is greater than or equal to a value, indicating an alumina hydrate having an amorphous structure. That is,
The alumina hydrate used in the present invention is an alumina hydrate in which at least n is more than 1 and less than 3.

The shape of the alumina hydrate used in the present invention is a plate-like alumina hydrate having an average aspect ratio of 3 to 7 and having a plate-like pseudo-boehmite structure. More preferably, a tabular pseudo-boehmite alumina hydrate having an average aspect ratio of 3 to 5 is desirable. The aspect ratio is expressed as the ratio of the “diameter” to the “thickness” of a particle. Here, the “diameter” indicates the diameter of a circle equal to the projected area of the particles when the alumina hydrate is observed with an electron microscope. When the aspect ratio is smaller than the above range, the pore size distribution of the ink image receiving layer becomes narrower and the ink absorbency becomes worse, and the alumina hydrate having the aspect ratio larger than the above range has the same particle size. It is difficult to manufacture, and the transparency of the coating film becomes poor.

It is known that alumina hydrate has a hair bundle (pillar) shape and a flat shape other than that. The present inventors have found that this plate-like alumina hydrate has better dispersibility than that of a hair bundle (pillar) shape, and impairs the ink absorption when an ink absorbing layer is formed. No,
Although an ink absorbing layer that is less likely to crack can be obtained and is excellent in film forming properties, hair bundles are easily cracked and poor in film forming properties of the ink absorbing layer.

In order for the alumina hydrate to have a sufficient ink absorption rate, the average pore radius of the alumina hydrate should be 1 to 10
nm, particularly preferably 2 to 7 nm. If the pore radius is too small, it becomes difficult to absorb the ink. On the other hand, if the pore radius is too large, fixation of the dye in the ink will be poor, and the image will bleed.

In order for the alumina hydrate to have a sufficient ink absorption capacity, the pore volume of the alumina hydrate should be 0.1 to 0.5.
It is preferably in the range of 8 ml / g, especially 0.4 to
It is preferably in the range of 0.6 ml / g. If the pore volume of the ink absorbing layer is large, cracks and powder fall may occur in the ink absorbing layer, and if the pore volume is small, the ink absorption tends to be slow. Moreover, the pore radius is 2 nm or more.
The pore volume of 10 nm is desirably 0.1 ml / g or more.
Outside this range, the adsorption of the dye in the ink becomes poor, which is not preferable. Further, the solvent absorption amount per unit area of the ink absorbing layer is preferably 5 ml / m ² or more, particularly preferably 10 ml / m ² or more. When the amount of solvent absorption per unit area is small, the ink may overflow especially when multicolor printing is performed.

In order for the alumina hydrate to sufficiently absorb and fix the dye in the ink, the BET specific surface area is 70 to 300 m.
It is preferably in the range of ² / g. If the BET specific surface area is too large, the efficiency of fixation of the dye in the ink becomes worse due to the larger pore size distribution, resulting in image bleeding. Conversely, if the BET specific surface area is too small, dispersion of the alumina hydrate becomes difficult.

In order to increase the concentration of the dispersion of alumina hydrate, the number of hydroxyl groups on the surface of alumina hydrate should be 10 ²⁰ /
g or more. When the number of surface hydroxyl groups is small, alumina hydrate tends to aggregate, and it becomes difficult to increase the concentration of the dispersion.

Further, in order to stabilize the dispersion of alumina hydrate, various acids are usually added to the dispersion.
Examples of such acids include nitric acid, hydrochloric acid, hydrobromic acid, acetic acid, formic acid, ferric chloride, and aluminum chloride, but the present invention is not limited thereto.

The alumina hydrate can be produced by a known method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, and hydrolysis of aluminate. The particle size, pore size, pore volume, specific surface area, number of surface hydroxyl groups, etc. of the alumina hydrate can be controlled by the deposition temperature, aging time, liquid pH, liquid concentration, coexisting salts and the like.

As a method for obtaining alumina hydrate, there are known methods described in JP-A-57-88074, JP-A-62-56321, JP-A-4-275917, JP-A-6-64918, and 7-10.
Nos. 535 and 7-267633, U.S. Pat.
656,321, Am. Ceramic So
c. Bull. , 54, 289 (1975) discloses a method of hydrolyzing an aluminum alkoxide. As these aluminum alkoxides, isopropoxide, propoxide, 2-butoxide and the like can be mentioned. In this method, very high-purity alumina hydrate can be obtained.

Other methods for obtaining alumina hydrate are described in JP-A-54-116398 and JP-A-55-23034.
The method of obtaining an inorganic salt of aluminum or a hydrate thereof as a raw material as exemplified in JP-A Nos. 55-27824 and 56-120508 is generally used. As these inorganic salts, for example, aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride,
Examples thereof include inorganic salts such as ammonium alum, sodium aluminate, potassium aluminate, and aluminum hydroxide, and hydrates of these inorganic salts.

In the present invention, specific examples of known methods for producing alumina hydrate are shown below, but the present invention is not limited thereto.

As a specific example, alumina hydrate is obtained by a neutralization reaction between an acidic aqueous solution of an aluminum salt such as aluminum sulfate, aluminum nitrate and aluminum chloride and a basic aqueous solution such as sodium aluminate, sodium hydroxide and aqueous ammonia. Can be manufactured. in this case,
The mixture is mixed so that the amount of alumina hydrate formed in the liquid does not exceed 5% by weight, the pH is 6 to 10, and the temperature is 20 to 100 ° C.
The reaction is generally performed under the following conditions. Further, a pH as described in JP-A-56-120508 is used.
Is alternately changed to the acid and base side to grow alumina hydrate crystals, alumina hydrate obtained from an inorganic salt of aluminum as described in JP-B-4-33728, and a buyer. It can also be produced by a method in which alumina obtained by the method is mixed and alumina is rehydrated.

The water-soluble binder used in the present invention has a degree of polymerization of at least 2,000 and a degree of saponification of at least 88%.
Less than 00% of polyvinyl alcohol is particularly preferable from the viewpoint of mixing with alumina hydrate, adjusting the viscosity of the coating solution, and forming a film. When polyvinyl alcohol having a degree of polymerization of less than 2,000 is used, cracks are likely to occur because the strength of the coating film is low. On the other hand, when the saponification degree is less than 88%, the strength of the coating film is weakened and cracks are easily formed. Further, if the saponification degree is 100%, the reactivity with the alumina hydrate is high, and the coating liquid is apt to gel, which is not preferable.

As the binder, other than polyvinyl alcohol, starch and its modified products, gelatin and their modified products, natural polymer resins such as casein, pullulan, arabic gum, karaya gum, albumin or derivatives thereof, cationic modified, silanol modified Modified polyvinyl alcohol such as SBR latex, NBR latex, methyl methacrylate-butadiene copolymer,
Latexes such as ethylene-vinyl acetate copolymer, polyacrylamide, vinyl polymers such as polyvinylpyrrolidone, polyethyleneimine, polypropylene glycol, polyethylene glycol, maleic anhydride or a copolymer thereof, and the like, but the present invention It is not limited to these. Also, when using these water-soluble binders in combination, the total amount of the water-soluble binders,
It is preferably from 5 to 20% by weight, particularly preferably from 8 to 15% by weight, based on alumina hydrate.
Below the above range, the film formability of the ink absorbing layer is deteriorated, and cracks and powder fall of the coating film are apt to occur. Getting worse.

When the alumina hydrate and the binder are mixed, the viscosity tends to increase with time and the thixotropy tends to appear. However, by controlling the temperature of the coating solution, the change in the viscosity of the coating solution over time can be observed. It can be avoided and the coating stability is improved, and the coated surface quality can be kept good. The temperature of the coating solution is preferably from 20C to 70C, more preferably from 40C to 50C. If the temperature is lower than 20 ° C., the coating liquid has a strong thixotropic property, making it difficult to apply the coating liquid.

Further, boric acid or borate may be added as a crosslinking agent for the binder for the purpose of improving film formability and water resistance. At that time, when the coating liquid is heated, the coating liquid is further stabilized.
It is preferable to heat the mixture.

The amount of boric acid or borate added is H ₃ B
0.1 to 10 with respect to polyvinyl alcohol in terms of O ₃
% By weight, preferably 1 to 5% by weight. The amount added is 0.
When the amount is less than 1% by weight, the effect is not sufficiently exhibited, and when the amount exceeds 10%, the viscosity of the coating liquid changes remarkably, and the stability of the coating is deteriorated.

As boric acid, not only orthoboric acid but also metaboric acid and hypoboric acid can be used. As the borate, these soluble salts are preferable, and specifically, Na ₂ B ₄ O _{7.
10H 2 O, NaBO 2 · 4H} 2 0, K 2 B 4 O 7 · 5H
_{2 O, NH 4 HB 4 O} 7 · 3H 2 O, but NH ₄ BO _2, and the like, the present invention is not limited thereto.

The ink absorbing layer coating conditions (coating device, coating liquid temperature, viscosity, etc.) and drying conditions (drying temperature,
The physical properties of the ink-absorbing layer can be controlled by the drying time, temperature gradient, air volume, air application, humidity, etc.).

The drying temperature of the ink absorbing layer depends on the heat resistance of the support, but is preferably from 60 to 200 ° C., more preferably from 70 to 150 ° C.
℃ is good. Further, after the ink absorbing layer is sufficiently dried, if heat treatment is performed within a range that does not adversely affect the support, the pore volume of the ink absorbing layer becomes large, so that the ink absorbing property is improved, and the water resistance of the ink absorbing layer is also improved. Get better. The heat treatment temperature depends on the base material, but is 100 to 200.
° C, preferably 120 to 150 ° C.

In the production of the recording material for ink jet in the present invention, as a support used, for example, a thermoplastic film, a resin-coated paper, a coated paper and the like are mainly used. The support is not particularly limited as long as it is a support on which an ink receiving layer such as a vapor deposition film or a cloth can be provided.

As the thermoplastic film, polyester, polypropylene, polyamide, polyvinyl chloride, polystyrene, polymethyl methacrylate, cellulose acetate, polyethylene, polycarbonate and the like can be used.

The support in the present invention may be provided with an anchor layer for the purpose of improving the adhesion between the ink absorbing layer and the support. A hydrophilic binder such as gelatin, a solvent-soluble binder such as butyral, a latex, a curing agent, a pigment, a surfactant and the like can be appropriately added to the anchor layer.

The support in the present invention has an antistatic property,
For transportability, curl prevention, writing, gluing, etc.
Various back coat layers can be applied. An inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a lubricant, a surfactant, and the like can be added to the back coat layer in an appropriate combination.

In addition, not only the composition of the ink absorbing layer but also the characteristics of the support are important in order to obtain an ink jet recording material having a photographic paper-like glossiness and texture. To get the photographic paper-like glossiness and texture of a photo,
It is preferable to use a polyester film or a resin-coated paper, and it is particularly preferable that the Hunter whiteness of the support measured by JIS-P-8123 is 65% or more.

Further, in order to obtain the glossiness and texture of a photographic paper, the hunter whiteness measured by JIS-P-8123 on the ink-absorbing layer side when the ink-absorbing layer is provided on a support. Is preferably 65% or more, and the 60-degree specular gloss measured by JIS-Z-8741 on the ink absorbing layer side is preferably 30% or more.

When a polyester film is used as the support for use in the present invention, the thickness thereof is not particularly limited, but is preferably about 10 to 200 μm from the viewpoint of handling properties and printer paper-passing suitability.

In the present invention, the polyester film refers to an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid or an ester thereof, and a polyester film such as ethylene glycol, diethylene glycol, 1,4-butanediol, or neopentyl glycol. Polyester obtained by polycondensation with a polyhydric alcohol is a film, usually roll stretching, tenter stretching,
In many cases, orientation processing is performed by processing such as inflation stretching.

Specific examples of the polyester include polyethylene terephthalate, polyethylene butylene terephthalate, polyethylene-2,6-naphthalate and copolymers thereof with other components, but the present invention is not limited to these. .

Examples of the method for increasing the whiteness of the polyester film include a method in which inorganic fine particles such as barium sulfate, titanium dioxide, calcium carbonate, silicon dioxide, aluminum oxide, kaolin, and talc are contained in the polyester film, and a method in which a white paint is applied to the surface. And the like.

In order to provide cushioning and concealing properties, a void-containing film having a large number of voids inside the film, for example, a foamed polyester film can also be used.

When a resin-coated paper is used as the support in the present invention, the thickness does not need to be particularly limited.
Those having a thickness of about 0 to 300 μm are preferred. Further, in order to obtain the texture of a photographic paper, it is preferably about 200 to 300 μm.

The base paper for the resin-coated paper is not particularly limited.
Generally used paper can be used, but preferably,
For example, a smooth base paper as used for a photographic support is preferable. As the pulp constituting the base paper, a natural pulp, a recycled pulp, a synthetic pulp, or the like is used alone or in combination of two or more. The base paper is blended with additives generally used in papermaking, such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, a fluorescent whitening agent, and a dye. Furthermore,
Surface sizing agent, surface paper strength agent, optical brightener, antistatic agent,
A dye, an anchoring agent or the like may be applied on the surface.

The base paper for the resin-coated paper is preferably one having good surface smoothness which is compressed by applying pressure with a calendar or the like during or after papermaking, and the smoothness of Beck measured according to JIS-P-8119 is preferred. Those having a degree of 200 seconds or more are particularly preferred. The basis weight is preferably from 30 to 250 g / m ² .

The whiteness of base paper for resin-coated paper is determined according to JIS-
If the Hunter whiteness measured by P-8123 is 65% or more, the whiteness is high, and a high-quality recording material can be obtained. However, the whiteness required depends on the purpose, and unbleached pulp is used in combination with natural pulp. A brown base paper may be used. Alternatively, base paper colored with a coloring agent such as a dye may be used.

As the coating resin for the resin-coated paper, a polyolefin resin is preferable, and a polyethylene resin is particularly preferable. Further, low density polyethylene, medium density polyethylene, high density polyethylene or a mixture thereof can be used. The low-density polyethylene referred to here has a density of 0.
It is 915 to 0.930 g / cm ³ and is usually manufactured by a high-pressure method. On the other hand, high-density polyethylene has a density of 0.950 g / cm ³ or more,
It is usually produced by a low pressure method or a medium pressure method. These polyethylene resins having various densities and melt flow rates can be used alone or in combination of two or more.

The structure of the resin layer of the resin-coated paper may be a single layer or a multilayer of two or more layers. Also in this case, the above polyolefin resins can be used alone or in combination of two or more. Further, the respective layers of the multilayer may have different compositions or the same composition.
As a method of forming a multilayer resin layer, any of a coextrusion coating method and a sequential coating method may be adopted.

On the other hand, the resin layer of the resin-coated paper can be formed by coating a latex having a film forming ability. For example, it can be formed by coating a latex having a low minimum film formation temperature (MFT) on a base paper for resin-coated paper and then heating the latex to a temperature not lower than the minimum film formation temperature.

The thickness of the coating resin layer of the resin-coated paper is not particularly limited, but it is generally coated on the surface only or on both the front and back to a thickness of 5 to 50 μm.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearamide and arachidic amide,
Fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, 2,6-di-t-butyl-p-cresol,
Antioxidants such as triphenyl phosphite, pigments and dyes of blue such as cobalt blue, ultramarine blue, cecilian blue and phthalocyanine blue, pigments and dyes of magenta such as cobalt violet, fast violet and manganese violet, fluorescent whitening agents, ultraviolet rays Various additives such as an absorbent can be appropriately combined and added.

The resin-coated paper used as a support in the present invention is produced by a so-called extrusion coating method in which a heated and melted polyolefin resin is cast on a running base paper. Further, in order to improve the adhesiveness between the resin and the base paper, it is preferable to perform an activation treatment such as a corona discharge treatment or a flame treatment on the base paper before coating the resin on the base paper. The surface (surface) of the support on which the ink absorbing layer is applied,
Depending on its use, it has a glossy surface, a matte surface, and the like, and a glossy surface is particularly preferably used. It is not always necessary to coat the back surface with a resin, but it is preferable to coat the resin from the viewpoint of curling prevention. The back surface is usually a matte surface, and activation treatment such as corona discharge treatment and flame treatment can be applied to the front surface or both the front and back surfaces as required.

The present invention can be applied to a high-transparency ink-jet recording material that can be used as an OHP film. Not only the composition of the ink absorbing layer but also the properties of the support are important. As for the light transmittance when used as an OHP film, the haze (cloudiness value) is closer to human feeling than the total light transmittance, and the haze (JIS-K-7105) according to JIS-K-7105 is used for the ink absorbing layer of the present invention. It is particularly preferable that the support is a transparent support having a haze value of 3.0 or less.

The haze of the ink jet recording material when used as an OHP film is determined according to the JIS-K-7 of the ink jet recording material provided with an ink absorbing layer on a support.
It is particularly preferred that the haze (haze value) according to 105 is 10.0 or less.

The haze (haze value) can be expressed by the ratio of the diffuse transmittance and the total light transmittance measured by using an integrating sphere light transmittance measuring device according to JIS-K-7.
105.

In a recording material such as an OHP film which is required to have a light-transmitting property, the thickness of the support to be used is not particularly limited, but is preferably about 50 to 200 μm from the viewpoint of handling properties and aptitude for passing a printer. preferable.

In the production of the recording material for ink jet in the present invention, good coatability can be obtained in many cases without adding a surfactant, but in order to further improve coatability, or For the purpose of adjusting the dot diameter when the ink adheres to the ink absorbing layer, a surfactant can be added. The surfactant used is preferably a nonionic surfactant, but may be selected from anionic, cationic, nonionic and betaine types as necessary. It may be something. One or more surfactants may be used in combination. The amount of the surfactant to be added is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, based on 100 parts by weight of alumina hydrate constituting the ink absorbing layer in terms of solid content.

Further, in addition to the above surfactants, inorganic pigments, coloring dyes, coloring pigments, fixing agents for ink dyes, ultraviolet absorbers, antioxidants, pigment dispersants, defoamers, leveling agents, preservatives Various known additives such as an agent, an optical brightener, a viscosity stabilizer, and a pH adjuster can also be added.

In order to improve the resolution of an image,
When agglomeration or the like does not occur when mixed with the dispersion of alumina hydrate, the ink absorbing layer contains a water repellent or sizing agent of a fluororesin type, a silicone resin type or an alkyl ketene dimer type. The resolution of an image can be improved by controlling the print dot diameter. As these fluorine resin-based, silicone resin-based or alkyl ketene dimer-based water repellents or sizing agents, commercially available ones can be used. Either of these solutions or aqueous emulsions can be used. The print dot diameter can be controlled by the amount of these additions to the ink absorbing layer. The addition amount varies depending on each component, concentration and desired print dot diameter, but is usually 0.05 to 10% by weight, particularly preferably 0.1 to 5% by weight, based on the total solid content of the ink absorbing layer as an effective solid component. %.

The ink absorbing layer in the present invention is formed by applying and drying using a coating apparatus. As a coating method of the coating liquid, for example, a slide hopper method, a curtain method, an extrusion method, an air knife method,
A commonly used coating method such as a roll coating method and a rod bar coating method is used.

The ink absorbing layer is provided on at least one side of the support, but may be provided on both sides of the support for the purpose of preventing curling or the like.

The coating amount of the ink absorbing layer coating liquid is 3 to 50 g / m ² , more preferably ²⁰ to 45 g in terms of solid content.
/ M ² . If the coating amount is more than that, the drying property of the ink absorbing layer deteriorates, and cracks are extremely likely to occur, which is not preferable.

[0072]

EXAMPLES The present invention will be described below in detail with reference to examples, but the contents of the present invention are not limited to the examples.

Example 1 (Synthesis of Alumina Hydrate) An example of the synthesis of alumina hydrate used for the ink absorbing layer is shown below. All the raw materials used were commercial products and were used as such without any particular purification.

[0074] 1200 g of ion-exchanged water and 900 g of isopropyl alcohol were charged into a 3 L reactor and heated to 75 ° C. 408 g of aluminum isopropoxide was added, and hydrolysis was performed at 75 ° C. for 24 hours and at 95 ° C. for 4 hours. Thereafter, 24 g of acetic acid was added, and the mixture was stirred at 95 ° C. for 48 hours, and then concentrated so that the solid concentration became 15%, to obtain a white alumina hydrate dispersion.

The sol was dried at room temperature and measured by X-ray diffraction, which showed a pseudo-boehmite structure. When the average particle size was measured with a transmission electron microscope, it was found to be about 30 n.
m and alumina hydrate having a plate-like pseudo-boehmite structure with an aspect ratio of 6. In addition, the BET specific surface area, the average pore radius, the pore radius
When the pore volume at 30 nm and the pore volume at a pore radius of 2 nm to 10 nm were measured, 136 m ² / g and 5, respectively.
8 nm, 0.54 ml / g and 0.50 ml / g.

(Preparation of Inkjet Recording Material) Polyvinyl alcohol having a saponification degree of 96.5% and a polymerization degree of 1700 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 g of the prepared dispersion liquid of alumina hydrate having a plate-like pseudo-boehmite structure. Product name MA-
15 g of a 10% aqueous solution of 17) was mixed well and stirred to obtain a coating dispersion. After the dispersion was heated to 50 ° C., the haze (cloudiness value) according to JIS-K-7105 was 2.
A transparent polyester film (Lumirror 125T, trade name, manufactured by Toray Industries, Ltd.), which had a surface easy adhesion treatment of 19, weighed 20 g / m ² , 25 g / m ² , and 30 after drying, respectively.
g / m ² , 35 g / m ² , and 40 g / m ² were applied, dried, and heat-treated at 140 ° C. for 5 minutes to obtain an inkjet recording material.

Example 2 A 100% dispersion of the alumina hydrate having a plate-like pseudo-boehmite structure used in Example 1 had a degree of saponification of 97% and a degree of polymerization of 260.
15 g of a 10% aqueous solution of polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: MA-26) was added and mixed well.
The mixture was stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

Example 3 100 g of the dispersion of the alumina hydrate having a plate-like pseudo-boehmite structure used in Example 1 was subjected to a saponification degree of 93.5% and a polymerization degree of 3.
500 polyvinyl alcohols (Kuraray Co., trade name P
15-g of a 10% aqueous solution of VA-635) was added, mixed well, and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

Example 4 15 g of propylene glycol, 97% of a saponification degree and a polymerization degree of 2600 polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd.) were added to 100 g of the alumina hydrate dispersion having a plate-like pseudo-boehmite structure used in Example 1. 15 g of a 10% aqueous solution of trade name MA-26) was added, mixed well, and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

Example 5 15 g of propylene glycol, polyvinyl alcohol having a saponification degree of 93.5% and a polymerization degree of 3500 (manufactured by Kuraray Co., Ltd.) were added to the dispersion liquid of alumina hydrate having a plate-like pseudo-boehmite structure used in Example 1. 15 g of a 10% aqueous solution of PVA-635) was added, mixed well, and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

Example 6 A 5% aqueous boric acid solution was added to the coating dispersion used in Example 1.
A recording material for ink-jet recording was obtained in the same manner as in Example 1 except that 5 g was added, followed by coating.

Example 7 A 5% aqueous boric acid solution was added to the coating dispersion used in Example 2.
A recording material for ink-jet recording was obtained in the same manner as in Example 1 except that 5 g was added, followed by coating.

Comparative Example 1 Commercially available alumina hydrate dispersion containing a deflocculant (catalyst AS-3, trade name, manufactured by Catalyst Chemical Industry Co., Ltd., solid content concentration:
1000 g (7% by weight in terms of Al ₂ O ₃ ) was dried with a spray drier to obtain xerogel. The residual water content of this xerogel was 5.3%. The obtained xerogel was redispersed in water to obtain an alumina hydrate dispersion such that the solid content concentration became 25%. The average particle size of this dispersion of alumina hydrate was measured with a transmission electron microscope.
nm, and a columnar alumina sol having an aspect ratio of 1.1 to 1.5. Also, BE adsorption and desorption by nitrogen
T specific surface area, average pore radius, pore radius 1 nm to 30 nm
When the pore volume and the pore volume of the pore radius of 2 nm to 10 nm were measured, 261 m ² / g and 6, respectively.
7 nm, 0.73 ml / g and 0.68 ml / g.

100 g of the prepared dispersion of alumina hydrate
Polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: MA-17) having a saponification degree of 96.5% and a polymerization degree of 1700
25 g of a 0% aqueous solution was mixed well and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

Comparative Example 2 A 100% aqueous solution of polyvinyl alcohol (trade name PA-24, manufactured by Shin-Etsu Chemical Co., Ltd.) having a saponification degree of 88% and a polymerization degree of 2400 was added to 100 g of the alumina hydrate dispersion used in Comparative Example 1. 25 g was added, mixed well, and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used. Comparative Example 3 25 g of a 10% aqueous solution of polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: MA-26) having a degree of saponification of 97% and a degree of polymerization of 2,600 was added to 100 g of the alumina hydrate dispersion used in Comparative Example 1. The mixture was thoroughly mixed and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

Comparative Example 4 A saponification degree of 96.5 was added to 100 g of a commercially available dispersion of alumina hydrate (catalyst AS-3, trade name, manufactured by Catalyst Chemical Industry Co., Ltd.).
9.2 g of a 10% aqueous solution of polyvinyl alcohol (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: MA-17) having a degree of polymerization of 1700
Was thoroughly mixed and stirred to obtain a coating dispersion. A recording material for ink jet was obtained in the same manner as in Example 1 except that this dispersion was used.

(Evaluation 1) In Table 1, the coating state at each coating amount was evaluated. The state of the coating film was evaluated by visual inspection. If no cracks were found on the surface, it was evaluated as ○. If a fine crack having a width of about 1 mm was found on the surface of the coating, Δ was found. The result was evaluated as x.

[0088]

[Table 1]

(Evaluation 2) Examples 1 to 7 and Comparative Examples 1 to
An ink jet recording material of the coating weight 20 g / m ² and 30 g / m ² obtained in 4 using a Canon full color ink jet printer BJC-600 J performs printing, ink absorption properties, by water drop of coating Water resistance evaluation and haze measurement were performed. In addition, 5 mm
In the case of the recording material for ink-jet having a crack having a width larger than the width and having a rating of 1 in the evaluation 1, the printing was not performed because the crack of the coating film occurred on the entire surface.

In Table 2, the ink absorption and the coating water resistance were evaluated. For the column of ink absorbency in Table 2, the ink drying state immediately after printing of the solid printing portion of single color and two-color printing was visually observed and evaluated, and those that could be printed without any ink overflow were evaluated as ○, The ink was slightly overflowed and printing unevenness occurred, and the ink was overflowed was evaluated as x. In the column of water resistance of the coating film, water droplets were dropped on the coating film, and those having no dripping marks after natural drying were evaluated as ○. In addition, when water droplets were left immediately after wiping the water droplets, the result was evaluated as x. In the haze column, this coating amount is 30 g.
/ M ² of JIS-K-7 for recording material for inkjet
105 represents haze.

[0091]

[Table 2]

[0092]

As is clear from the examples, it is possible to suppress the fine cracks in the ink absorbing layer at the time of coating and drying, to quickly absorb the ink and to have a good ink absorbability. Thus, a recording material for ink-jet having an ink-absorbing layer can be provided. Further, it was possible to provide an ink jet recording material having high transparency which can be used as an OHP film.

Claims (3)

[Claims] 1. An ink-jet recording material having an ink-absorbing layer provided on a support, wherein the ink-absorbing layer has an average aspect ratio of 3 to 7 and a pore volume in the range of a pore radius of 2 nm or more and 10 nm or less. A recording material for ink-jet recording, characterized by containing a hydrated alumina hydrate having a pseudoboehmite structure in a plate shape of 1 ml / g or more and polyvinyl alcohol. 2. Polyvinyl alcohol having a degree of polymerization of 20
2. The recording material for ink-jet recording according to claim 1, wherein the saponification degree is not less than 00 and less than 88%. 3. The ink-jet recording material according to claim 1, wherein the polyvinyl alcohol is cross-linked by at least one selected from boric acid and borate.