JP2001138627A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photo-like ink jet recording sheet having excellent preservability without craze, high ink absorbability and high gloss. SOLUTION: In the ink jet recording sheet comprising an ink receiving layer mainly containing a vapor phase method silica, the layer contains at least one type of a water soluble salt of a polyvalent metal.

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 more particularly, to an ink jet recording sheet having no cracks on the surface of an ink receiving layer, high gloss, and excellent ink absorption. .

[0002]

2. Description of the Related Art As a recording material used in an ink jet recording system, a pigment such as amorphous silica is coated on a support called a normal paper or an ink jet recording paper by a porous material comprising a water-soluble binder such as polyvinyl alcohol. There is known a recording material provided with an ink absorbing layer.

[0003] For example, Japanese Patent Application Laid-Open No. 55-51583,
Nos. 6-157, 57-107879, 57-10
No. 7880, No. 59-230787, No. 62-160
No. 277, No. 62-184879, No. 62-1833
As disclosed in JP-A-82 and JP-A-64-11877, a recording material obtained by applying a silicon-containing pigment such as silica to a paper support together with an aqueous binder has been proposed.

[0004] Also, Japanese Patent Publication No. 3-56552,
No. 188287, No. 10-81064, No. 10
No.-119423, No. 10-175365, No. 10
-203006, 10-217601, 11
No. -20300, No. 11-20306, No. 11-
Japanese Patent Publication No. 34481 and the like disclose a technique for improving gloss and ink absorbency by using synthetic silica fine particles obtained by a gas phase method (hereinafter, referred to as gas phase silica).

Conventionally, paper has been generally used as a support for the above-described recording material, and the paper itself has a role as an ink absorbing layer. In recent years, while a photo-like recording sheet has been demanded, a recording sheet using a paper support has problems such as gloss, texture, water resistance, cockling (wrinkles or wavy) after printing, and is water-resistant. For example, a resin-laminated paper (polyolefin resin-coated paper) obtained by laminating a polyolefin resin such as polyethylene on both sides of paper has been used. However, since these water-resistant supports cannot absorb ink unlike paper supports, the ink absorbency of the ink receiving layer provided on the support is important, and the void capacity of the ink receiving layer is important. Need to be increased. Therefore, it was necessary to increase the content of the pigment and to reduce the ratio of the binder to the pigment in order to increase the porosity. However, by increasing the pigment content and further reducing the binder ratio, cracks were likely to occur during drying, and the quality was significantly reduced.

[0006] In particular, the above-mentioned fumed silica is characterized in that high average ink absorption and high gloss can be obtained because the average particle size of the primary particles is a few nm to several tens nm.
On the other hand, there is a problem that cracks easily occur.

Further, the recording material using fumed silica as described above has a problem that a printed image is liable to be discolored during storage after printing. That is, discoloration due to light and discoloration due to a trace amount of gas in the air were likely to occur. In particular, discoloration due to trace gases in the atmosphere was serious. Further, it has been found that these problems are likely to occur when the amount of the binder is reduced in order to increase the ink absorbency.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photo-like ink jet recording sheet which is free from cracks, has high ink absorbency, is high in gloss, and has high gloss. Another object of the present invention is to provide an ink jet recording sheet having excellent image storability (light fastness and gas fastness) after printing.

[0009]

An object of the present invention is to provide an ink jet recording sheet provided with an ink receiving layer mainly containing fumed silica, wherein the ink receiving layer contains at least a water-soluble salt of a polyvalent metal. This has been achieved by an ink jet recording sheet characterized in that it contains one type.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The ink jet recording sheet of the present invention absorbs ink in the voids formed in the film by the inorganic solid fine particles, and it is necessary to achieve a high void volume in order to exhibit a high ink absorption capacity. For this reason, it is necessary to contain a relatively large amount of inorganic fine particles, and the amount of the hydrophilic binder is preferably reduced to fill the voids.

In the present invention, fumed silica is 8 g / g.
m ² or more, and more preferably 10 to 25 g / m ² . If less than this range,
The ink absorbency is poor, and as the amount increases, cracks are more likely to occur. The amount of the hydrophilic binder is preferably 30% by weight or less, more preferably 10 to 30% by weight, based on the fumed silica. By reducing the ratio of the hydrophilic binder in this manner, the ink absorbency is improved, but cracks are likely to occur, and the present invention is characterized by satisfying these properties simultaneously.

In the present invention, the phrase "fumed silica is mainly contained in the ink receiving layer" means that the fumed silica is at least 50% by weight, preferably 60% by weight, based on the total solid content of the ink receiving layer.
%, More preferably 65% by weight or more.

[0013] Synthetic silica includes those obtained by a wet method and those obtained by a gas phase method. The present invention is characterized by using synthetic silica by a gas phase method. Usually, silica fine particles often refer to wet process silica. As the wet process silica, silica sol obtained by double decomposition with an acid or the like of sodium silicate or an ion exchange resin layer, or colloidal silica obtained by heating and aging this silica sol,
The silica sol is gelled and the formation conditions are changed to change silica gel, where the primary particles of several microns to 10 microns become siloxane-bonded three-dimensional secondary particles, furthermore silica sol, sodium silicate, sodium aluminate Synthetic silicate compounds mainly composed of silicic acid, such as those obtained by heating and producing the like.

[0014] The fumed silica is also called a dry method with respect to a wet method, and is generally produced by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning it with hydrogen and oxygen is generally known, but instead of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane may be used alone or in a silicon tetrachloride. And can be used in a mixed state. The fumed silica is Aerosil from Nippon Aerosil Co., Ltd. and Q from Tokuyama Co., Ltd.
It is commercially available as the S type and can be obtained.

The average particle size of the primary particles of the fumed silica used in the present invention is preferably 30 nm or less. In order to obtain higher gloss, the average particle size is 3 to 10 nm and the specific surface area by the BET method is 250 m ² / g. Or more (preferably 250 to 50
(0 m ² / g). The BET method referred to in the present invention is one of the methods for measuring the surface area of a powder by a gas phase adsorption method, and is a method for determining the total surface area of 1 g of a sample, that is, the specific surface area, from an adsorption isotherm. Usually, nitrogen gas is often used as the adsorbed gas, and the method of measuring the amount of adsorption from the change in pressure or volume of the gas to be adsorbed is most often used. The most prominent for expressing isotherms for multimolecular adsorption is the Brunauer, Emmett, Teller equation, BE
It is called T type and is widely used for determining the surface area. BET
The surface area is obtained by calculating the amount of adsorption based on the formula and multiplying the area occupied by one adsorbed molecule on the surface.

In the present invention, as the hydrophilic binder used together with the fumed silica, various known binders can be used, but a hydrophilic binder which has high transparency and can obtain a higher ink permeability is preferably used. Can be In the use of the hydrophilic binder, it is important that the hydrophilic binder does not swell at the initial penetration of the ink and does not close the voids.From this viewpoint, a hydrophilic binder having a relatively low swelling property at around room temperature is preferable. Used. Particularly preferred hydrophilic binders are fully or partially saponified polyvinyl alcohols or cationically modified polyvinyl alcohols. For dispersion of fumed silica, a commonly known disperser such as a high-pressure homogenizer and a ball mill can be used.

Particularly preferred among polyvinyl alcohols are polyvinyl alcohols having a degree of saponification of 80 or more or completely saponified and having an average degree of polymerization of 200 to 5,000, preferably 500 to 5,000.

As the cation-modified polyvinyl alcohol, for example, as described in JP-A-61-10483, a primary to primary amino group or a quaternary ammonium group may be used as the main chain or side chain of polyvinyl alcohol. It is a polyvinyl alcohol contained therein.

In the present invention, it is preferable that the ink receiving layer contains a cationic polymer in order to increase the fixability of the coloring material in the ink and to further improve the color developing property.
Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, JP-A-59-20696, JP-A-59-33176, and JP-A-59-33176.
No. 33177, No. 59-155088, No. 60-11
No. 389, No. 60-49990, No. 60-83882
Nos. 60-109894 and 62-198493
No. 63-49478, No. 63-115780,
Nos. 63-280681, JP-A-1-40371, 6-234268, 7-125411, 10-
Nos. 52908 and 10-193776, primary to tertiary amine salt type compounds, quaternary ammonium salt type compounds, pyridinium salt type compounds, imidazoline type cationic compounds, Low molecular weight cationic substances such as ethylene oxide adducts of lower alkyl amines,
Further, cationic polymers such as polyallylamine, polyamine sulfone, polyvinylamine, chitosan, and neutralized products or partially neutralized products thereof with acids such as hydrochloric acid and acetic acid can be used. The molecular weight of these cationic polymers is
It is preferably 5,000 or more, more preferably about 5,000 to 100,000, and the amount of addition is about 0.05 to 2.0 g / m ² , preferably about 0.15 to 1.0 g / m ² .
By containing the above cationic polymer,
There is a problem that the water resistance is improved, but the light resistance is further deteriorated. The present invention has a feature that the water resistance and the light resistance can be simultaneously improved by using together with a water-soluble salt of a polyvalent metal.

Further, in order to improve the brittleness of the film, it is preferable to contain various oil droplets. Such oil droplets have a hydrophobic high boiling point having a solubility in water at room temperature of 0.01% by weight or less. Organic solvents (eg, liquid paraffin,
Dioctyl phthalate, tricresyl phosphate, silicon oil, etc.) and polymer particles (for example, particles obtained by polymerizing one or more polymerizable monomers such as styrene, butyl acrylate, divinylbenzene, butyl methacrylate, and hydroxyethyl methacrylate). Can be. Such oil droplets can be preferably used in the range of 10 to 50% by weight based on the hydrophilic binder.

The water-soluble salt of a polyvalent metal used in the present invention includes calcium, barium, manganese, copper, cobalt,
It is a water-soluble salt of a metal selected from nickel, aluminum, iron, zinc, zirconium, chromium, magnesium, tungsten, and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, calcium butyrate, barium acetate, barium sulfate, barium phosphate, barium oxalate, barium naphthoresorcin carboxylate, barium butyrate, manganese chloride, manganese acetate, Manganese formate dihydrate, ammonium manganese sulfate hexahydrate, cupric chloride, copper (II) ammonium chloride (II) dihydrate, copper sulfate, copper (II) butyrate, copper oxalate, copper phthalate, copper citrate , Copper gluconate, copper naphthene, cobalt chloride, cobalt thiocyanate, cobalt sulfate, cobalt (II) acetate, cobalt naphthenate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, sulfuric acid Nickel ammonium hexahydrate, nickel amidosulfate tetrahydrate, nickel sulfamate, 2
Nickel ethylhexanoate, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, aluminum acetate, aluminum lactate, basic aluminum thioglycolate, first bromide Iron, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, iron (III) citrate, iron (III) lactate trihydrate, triammonium iron oxalate (III) trihydrate Hydrate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zinc acetate, zinc lactate, zirconium acetate, zirconium chloride, zirconium chloride octahydrate, zirconium hydroxychloride, chromium acetate, chromium sulfate, Magnesium acetate, magnesium oxalate, magnesium sulfate, magnesium chloride hexahydrate,
Magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphate n hydrate and the like Can be In the present invention, the water-soluble salt of a polyvalent metal is 20 ° C.
1% by weight or more in water.

As a method for imparting the water-soluble salt of the polyvalent metal, a method of dissolving in water or a water-miscible organic solvent, followed by coating or spraying on an image receiving layer made of fumed silica, For example, it is added to a coating solution containing silica and applied by a usual method. The addition amount is preferably from 0.1 to 10% by weight, more preferably from 1 to 5% by weight, based on the fumed silica.

In the present invention, a surfactant can be added to the ink receiving layer. The surfactant used may be any of anionic, cationic, nonionic and betaine types, and may be of low molecular weight or high molecular weight. One or two or more surfactants are added to the ink receiving layer coating solution. When two or more surfactants are used in combination, an anionic surfactant and a cationic surfactant are used in combination. It is not preferable. The addition amount of the surfactant is preferably 0.001 to 5 g with respect to 100 g of the binder constituting the ink receiving layer,
More preferably, it is 0.01 to 3 g.

In the present invention, the ink-receiving layer may further contain, in addition to a surfactant and a hardener, a coloring dye, a coloring pigment, a fixing agent for the ink dye, an ultraviolet absorber, an antioxidant, a dispersant for the pigment, Antifoaming agent, leveling agent, preservative, optical brightener,
Various known additives such as a viscosity stabilizer and a pH adjuster can also be added.

The support used in the present invention is preferably a water-resistant support. As the water-resistant support, both a transparent support and an opaque support can be used. As the transparent support, any conventionally known ones can be used, for example, polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride, polyimide resin, cellophane, film or plate such as celluloid and A glass plate and the like are exemplified, and among these, a film made of polyethylene terephthalate is most preferably used.

Such a transparent water-resistant support preferably has a thickness of about 10 to 300 μm.

As the opaque water-resistant support, synthetic paper,
Conventionally known materials such as resin-coated paper, opaque film containing pigment, and foamed film can be used. From the viewpoint of gloss and smoothness, resin-coated paper and various films are more preferable,
Films made of resin-coated paper similar to a photographic support from the feeling of touch and high quality and a polyethylene terephthalate containing a pigment having high whiteness and strength are more preferably used.

The base paper constituting the resin-coated paper as the water-resistant support preferably used in the present invention is not particularly limited, and generally used paper can be used. More preferably, the base paper is used for, for example, a photographic support. Smooth base paper is preferred. As the pulp constituting the base paper, natural pulp, recycled pulp, synthetic pulp or the like may be 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.

Further, a surface sizing agent, a surface paper strengthening agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be coated on the surface.

The thickness of the base paper is not particularly limited. However, it is preferable that the base paper has good surface smoothness, for example, by applying pressure by using a calender or the like during or after papermaking, and has a basis weight of 30%. ~250g / m ² is preferred.

As the resin of the resin-coated paper, a polyolefin resin or a resin curable by an electron beam can be used.
The polyolefin resin is a low-density polyethylene, high-density polyethylene, polypropylene, polybutene, a homopolymer of an olefin such as polypentene or a copolymer of two or more olefins such as an ethylene-propylene copolymer and a mixture thereof, Those having various densities and melt viscosity indices (melt index) can be used alone or in combination.

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; zinc stearate; calcium stearate; Aluminum, metal salts of fatty acids such as magnesium stearate, antioxidants such as Irganox 1010 and Irganox 1076, blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue, cobalt violet, fast violet, and manganese purple It is preferable to add various additives such as magenta pigments and dyes, fluorescent brighteners and ultraviolet absorbers in an appropriate combination.

The resin-coated paper, which is preferably used in the present invention, is produced by a so-called extrusion coating method in which, in the case of a polyolefin resin, a hot-melt resin is cast on a running base paper. Coated. In the case of a resin that is cured by an electron beam, the resin is applied by a commonly used coater such as a gravure coater or a blade coater, and then irradiated with an electron beam to cure and coat the resin. Further, before coating the resin on the base paper, the base paper is preferably subjected to an activation treatment such as a corona discharge treatment or a flame treatment. The surface (surface) of the support on which the ink receiving layer is applied has a glossy surface, a matte surface, and the like, depending on the application, and the glossy surface is used particularly advantageously. It is not 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 the front surface or both front and back surfaces can be subjected to an activation treatment such as a corona discharge treatment or a flame treatment as required. The thickness of the resin coating layer is not particularly limited, but is generally 5 to 50 μm thick on the surface or on both sides.

The support in the present invention can be coated with various back coat layers for antistatic properties, transport properties, curling prevention properties, and the like. The back coat layer can contain an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like in an appropriate combination.

In the present invention, the method of applying the ink receiving layer is not particularly limited, and a known coating method can be used. For example, there are a slide lip system, a curtain system, an extrusion system, an air knife system, a roll coating system, a rod bar coating system, and the like.

In the present invention, the ink recording sheet may be provided with an ink absorbing layer, an ink fixing layer, an intermediate layer, a protective layer and the like in addition to the layer containing the solid fine particles. For example,
A water-soluble polymer layer may be provided below the layer containing solid fine particles, or a swelling layer may be provided above the layer containing solid fine particles.

The ink recording sheet of the present invention may be provided with various back coat layers on the support opposite to the ink receiving layer for antistatic properties, transport properties, curl preventing properties, and the like. The back coat layer can contain an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like in an appropriate combination.

[0038]

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. In addition, a part means a solid content weight part.

Example 1 LBKP (50 parts) and LBSP (50 parts) were used as supports.
Part) of a pulp blend of 120 g / m ² , and a resin composition composed of low-density polyethylene (70 parts), high-density polyethylene (20 parts) and titanium oxide (10 parts) applied to the surface at 25 g / m ^2. And high-density polyethylene (5
0 parts) and a low-density polyethylene (50 parts) resin coating paper prepared by applying 25 g / m ² .

An ink receiving layer coating solution having the following composition was prepared on the support, and the coating amount of fumed silica was 18 g in solid content.
/ M ² and dried by air at 50 ° C. to form an ink jet recording sheet.

<Recording sheet 1> Gas-phase silica 100 parts (trade name: Aerosil 380, manufactured by Nippon Aerosil Co., Ltd., average primary particle size: 7 nm) Alkylamine epichlorohydrin polycondensate (cationic polymer) 4 parts Polyvinyl alcohol 20 parts (Product name: PVA235, manufactured by Kuraray Co., Ltd., saponification degree 88%, average polymerization degree 3500) Boric acid 4 parts Amphoteric surfactant 0.3 part (Product name: SWAM AM-2150, manufactured by Nippon Surfactant)

<Recording Sheet 2> An ink jet recording sheet obtained by applying the recording sheet 1 in the same manner as in the recording sheet 1 except that the amount of polyvinyl alcohol added is 33 parts.

<Recording Sheet 3> An ink jet recording sheet obtained by coating in the same manner as recording sheet 1 except that 3 parts of cupric chloride was added to the composition of recording sheet 1.

<Recording Sheet 4> An ink jet recording sheet obtained by applying the recording sheet 1 in the same manner as the recording sheet 1 except that 3 parts of nickel sulfate was added to the composition of the recording sheet 1.

<Recording Sheet 5> An ink jet recording sheet obtained by applying the recording sheet 1 in the same manner as the recording sheet 1 except that 3 parts of sodium phosphotungstate was added to the composition of the recording sheet 1.

<Recording Sheet 6> An ink jet recording sheet obtained by applying the recording sheet 1 in the same manner as the recording sheet 1 except that 3 parts of zirconium chloride was added to the composition of the recording sheet 1.

<Recording Sheet 7> An ink jet recording sheet obtained by applying the recording sheet 1 in the same manner as the recording sheet 1 except that 3 parts of phosphomolybdic acid was added to the composition of the recording sheet 1.

The following evaluation was performed on each of the obtained ink jet recording sheets. Table 1 shows the results.

<Crack> The coated surface was visually observed, and the crack state was evaluated according to the following criteria. ：: No crack at all. Δ: Cracks are slightly observed. X: Cracks are clearly seen.

<Ink Absorption> Using a plotter (Novajet-PRO42e manufactured by ENCAD) and GS ink, C, M, and Y are printed at 100% each, and immediately after printing, PPC paper is overlaid on the printing section. The ink was lightly pressed and the amount of the ink transferred to the PPC paper was visually observed and evaluated according to the following criteria. ：: No transfer at all. Δ: Slightly transferred.

<Light resistance> Solid printing at a density of 1.0 was performed using CYMK ink using an ink jet printer (BJF600, manufactured by Canon Inc.), and the density was increased to 765 W / m ² at 765 W / m ^{2 using a} Suntest CPS photobleaching tester, manufactured by Atlas. After irradiation for a period of time, the density of the printed portion was measured. The density difference ΔD before and after light irradiation was measured and evaluated according to the following criteria. ：: ΔD ≦ 0.3 in all of CMY. Δ: Similarly, 0.3 <ΔD ≦ 0.5. ×: Any of CMY is ΔD> 0.5.

<Gas resistance> CY was measured using an inkjet printer (PM-770C manufactured by Seiko Epson Corporation).
Solid printing was performed with each of the MK inks, and after exposure to air at room temperature for 4 months, the density of the printed portion was measured, and the image remaining ratio (density after exposure / density before exposure) was determined. , The one with the lowest residual rate (%) is shown.

<Glossiness> The glossiness was measured according to the method described in JIS P-8142 (Test method for 75 ° specular glossiness of paper and paperboard).

[0054]

[Table 1] ───────────────────────────────── Recording sheet Crack Ink absorption Light resistance Light resistance (% ) Remarks ───────────────────────────────── 1 × ○ × 68 Comparison 2 △ △ × 78 Comparison 3 ○ ○ ８９ 89 of the present invention 4 ○ ○ 91 of the present invention 5 ○ ○ 95 of the present invention 6 ○ ○ ９０ 90 of the present invention 7 ○ ○ ９６ 96 of the present invention ────────────────── ───────────────

The glossiness of the recording sheets 4 to 7 of the present invention is as follows.
Although the glossiness was as high as 60 to 65%, the recording sheets 1, 2
Was reduced to 50% or less.

[0056]

As is evident from the above results, in an ink jet recording sheet provided with an ink receiving layer mainly containing fumed silica, the ink receiving layer contains a water-soluble salt of a polyvalent metal. , High gloss, high ink absorption, no cracks, and storage stability (light resistance,
An ink jet recording sheet having excellent gas resistance) can be provided.

Claims (3)

[Claims] 1. An ink jet recording sheet provided with an ink receiving layer mainly containing synthetic silica by a gas phase method on a support, wherein the ink receiving layer contains at least one water-soluble salt of a polyvalent metal. A sheet for inkjet recording characterized by the above. 2. An average particle diameter of primary particles of the fumed silica is 3 to 10 nm, and a specific surface area by a BET method is 25.
The inkjet recording sheet according to claim 1, wherein the amount is 0 m ² / g or more. 3. The ink receiving layer is formed of fumed silica.
25 g / m ² and containing, ink jet recording sheet according to claim 1 or 2 hydrophilic binder to the fumed silica, containing 30 wt% or less.