JP2000043401A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the rate of ink absorption, make a drying property fast after printing, and improve the glossiness by having a layer containing the specific rate of a water soluble polymer and a layer containing a synthetic silica of a specific average particle diameter of primary particles by a vapor phase method from the part near the support body. SOLUTION: This is based on a fundamental concept in which a vapor phase method silica of fine particles is disposed on a layer consisting of a water soluble polymer, and printed ink is permeated through a lower layer promptly to subsequently be absorbed by swelling of a water soluble polymer. Also, a synthetic silica having an average particle diameter of 50 nm or lower of vapor phase method silica primary particles used is required to be 5 g/m2. In addition, the content weight of the water soluble polymer is required to be 2 g/m2 or more. Furthermore, the combination and balance of both layers are important in a layer containing a large quantity of a vapor phase silica and a layer containing a large quantity of a water soluble polymer. In this manner, the rate of ink absorption is accomplished, and a drying property and glossiness can be enhanced.

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 excellent in ink absorption capacity, dryness after printing, and glossiness.

[0002]

2. Description of the Related Art A recording sheet used in an ink-jet recording system is composed of a support such as ordinary paper or ink-jet recording paper and a pigment such as amorphous silica and a water-soluble binder such as polyvinyl alcohol. A recording sheet provided with a porous ink absorbing layer has been used.

For example, see, for example, Japanese Patent Application Laid-Open No. 55-51583.
Nos. 56-157, 57-107879, 5
Nos. 7-107880, 59-230787, 60
-204390, 62-160277, 62-
Nos. 184879, 62-183382, and 64
As disclosed in JP-A-11877, a recording sheet obtained by applying a silicon-containing pigment such as silica to a paper support together with an aqueous binder has been proposed.

[0004] Japanese Patent Application Laid-Open Nos. Hei 3-215082 and 4-
Nos. 67986, 5-32037 and 10-81
No. 064 discloses a recording sheet in which fine silica particles or alumina sol is applied to the surface of a support together with a water-soluble binder.

On the other hand, many recording sheets provided with an ink receiving layer mainly composed of a water-soluble polymer have been proposed. For example, in JP-A-60-168651, use of polyvinyl alcohol and a polyacrylic acid-based water-soluble polymer is used, in JP-A-60-262885, use of hydroxyethyl cellulose is used, and in JP-A-61-181679, carboxymethyl cellulose is used. In JP-A-61-193879, a mixture of water-soluble cellulose and polyvinylpyrrolidone is used. In JP-A-62-263084, a receptor layer formed from an aqueous gelatin solution having a specific pH is used. JP-A-1-146784
The use of a mixture of gelatin and a surfactant is proposed in US Pat.

[0006] Many recording sheets containing a pigment such as amorphous silica and a specific binder have been proposed. For example, JP-A-6-32046 and JP-A-6-14380
No. 0, JP-A-7-32725, JP-A-7-14903
No. 7 and JP-A-8-34160 propose a combination of a pigment, a specific binder and a specific compound.

A recording sheet having a water-soluble polymer swelling layer provided on a void layer made of silica fine particles or alumina sol is disclosed in JP-A-9-323475. Recording sheets having a microporous ink-permeable layer made of a water-soluble polymer are described in JP-A-61-35275 and JP-A-62-196175, and a porous sheet made of a pigment is formed on a layer made of a water-soluble polymer. The recording sheet having a layer is disclosed in
Nos. 140878, 62-2228887 and 3-
No. 72460, No. 7-186521, No. 10-2
No. 9369 and the like.

The above-mentioned conventional recording sheets do not simultaneously satisfy the important properties of ink absorption capacity, dryness after printing, and glossiness. In particular, in recent years, large-sized high-speed plotters with a large amount of ink have become widespread, and the above-mentioned performance has become increasingly important.

[0009]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an ink jet recording sheet having a large ink absorption capacity, a high drying property after printing, and a high gloss.

[0010]

An object of the present invention is to provide a layer containing at least 2 g / m ^{2 of a} water-soluble polymer and a vapor phase method in which the average particle size of primary particles is 50 nm or less. This has been achieved by an ink jet recording sheet having at least a layer containing 5 g / m ² or more of silica.

Furthermore, a layer containing a water-soluble polymer and a layer containing silica synthesized by a gas phase method can be applied to printing of a large amount of ink by an ink jet recording sheet satisfying the following conditional expression 1. Conditional expression 1 (A × 2) + (B × 8) ≧ 40 In the formula, A represents the content per 1 m ^{2 of the} silica synthesized by the gas phase method, and B represents the content per 1 m ^{2 of the} water-soluble polymer. Indicates weight.

The use of fine particles of silica synthesized by the gas phase method (hereinafter referred to as gas phase silica) is disclosed in
The use of a water-soluble polymer is also described in the above-mentioned Japanese Patent Application Laid-Open No. 204204/1998 and 81064/1992, and is well known. However,
The present inventor has found that the above configuration of the present invention satisfies the ink absorption capacity, drying property and glossiness simultaneously.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Synthetic silica includes those obtained by a wet method and those obtained by a gas phase method. Usually, silica fine particles often refer to wet process silica. As wet silica, silica sol obtained by metathesis of sodium silicate with an acid or the like through an ion exchange resin layer, or colloidal silica obtained by heating and aging this silica sol, gelling silica sol, and changing the production conditions Several μm to 10
Silica such as those obtained by heating and generating silica sol, sodium silicate, sodium aluminate, etc., where the primary particles are three-dimensional secondary particles with siloxane bonds in the μm range There are synthetic silicon compounds and the like.

The fumed silica used in the present invention is also called a dry method as opposed to the above 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 commercially available as Aerosil from Nippon Aerosil Co., Ltd. and can be obtained.

The average particle size of the primary particles of the fumed silica used in the present invention is 50 nm or less, preferably 5 to 30 nm.
nm. The feature of the fumed silica is that the primary particles are present in a state of being secondary aggregated by being connected in a network structure or a chain shape, thereby obtaining high ink absorption. Further, since the primary particle diameter is very small, high gloss can be maintained even when used for the uppermost layer of the recording sheet.

The colloidal silica produced by the wet method has a very small primary particle diameter of several nm to several tens of nanometers. However, since it is present as a primary particle in isolation, when the coating film is formed, the particles are present in a dense state. Therefore, when used in the ink receiving layer, the gloss is high, but the porosity is poor and the ink absorption is reduced. In addition, secondary aggregated silica particles of several μm to 10 μm have high ink absorbency but reduce gloss. Alumina sol does not provide the desired ink absorbency, and requires high-temperature heat treatment at about 120 ° C. for film formation and water resistance. Melts to produce flisters).

According to the present invention, by arranging fine-particle fumed silica on a layer made of a water-soluble polymer, the printed ink can be quickly transmitted to the lower layer, and the transmitted ink can be swollen by the water-soluble polymer. It is based on the basic concept of absorption, and sets the fumed silica layer and the water-soluble polymer layer under specific conditions so as to be adaptable to a high-speed plotter with a large amount of ink. That is, it has been found that by satisfying the following conditional expression 1, it can be sufficiently applied to a high-speed plotter.

Conditional expression 1 (A × 2) + (B × 8) ≧ 40 where A is the content weight of fumed silica per m ² , and at least 5 g / m ^{2 is} required. B is the weight content of the water-soluble polymer per m ² , at least 2 g / m ²
is necessary. The fumed silica has about twice the ink holding capacity per unit weight, and the water-soluble polymer (the polymer that dissolves in water at 5% by weight or more at normal temperature and pressure) has about 8 times the capacity per unit weight. The above-mentioned conditional expression 1 was derived by empirically finding that there is an ink absorption capacity.

The ink absorption capacity of the water-soluble polymer was determined by applying a water-soluble polymer of 4 g / m ² onto a paper support coated with a polyethylene resin and drying the sample.
This was empirically obtained by visually observing whether or not the ink overflowed when printing was performed under the condition of ² ml / m ² . It has been confirmed that any polymer that dissolves in water at 5% by weight or more at normal temperature and normal pressure has the above-mentioned ink absorption capacity.

Even if only a layer containing a large amount of fumed silica or only a layer containing a large amount of a water-soluble polymer is provided, the ink absorbency, drying property and glossiness are simultaneously satisfied. Can not. It is important to use both in combination, and it is also important to balance them. Therefore, in the above conditional expression 1, the ratio of (A × 2) to (B × 8) is preferably in the range of 5: 1 to 1: 5,
In particular, the range of 4: 1 to 1: 4 is preferable, and the range of 3: 1 to 1 is further preferable.
A range of 1: 3 is preferred.

The content of fumed silica is 5 to 3 per m ^2.
0 g is preferable, and particularly preferably 5 to 20 g. The content of the water-soluble polymer is preferably ^{2 to} 10 g per m ² ,
Particularly, 3 to 8 g is preferable.

It is more preferable that the above-mentioned conditional expression 1 be satisfied. Conditional expression 2 (A × 2) + (B × 8) ≧ 50

In the present invention, the upper layer containing fumed silica preferably has a binder in order to maintain the properties as a film. As the binder, various known binders can be used, but polyvinyl alcohol or cation-modified polyvinyl alcohol having a good binding property to fumed silica is preferably used.

Particularly preferred among polyvinyl alcohols are those having a degree of saponification of 80 or more or completely saponified, and from the viewpoint of improving film forming properties and film brittleness, have an average degree of polymerization of 200 to 5000, preferably 500. ~ 3
000 are used.

As the cation-modified polyvinyl alcohol, for example, a tertiary amino group or a quaternary ammonium group as described in JP-A-61-10483 can be used in the seed chain or side chain of polyvinyl alcohol. Is a polyvinyl alcohol.

Although other hydrophilic binders can be used in combination, the content is preferably 20% by weight or less based on polyvinyl alcohol. The amount of the hydrophilic binder used together with the fumed silica is 50% by weight or less, preferably 30 to 1% by weight, based on the fumed silica.

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 not more than 0.01% by weight. 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.

In the case of the layer structure of the present invention, when the lower water-soluble polymer layer absorbs ink and swells, fine cracks are apt to be formed in the upper layer of the fumed silica layer. This crack causes a reduction in gloss. In order to avoid this, the layer containing fumed silica preferably contains a hydrophilic binder and a crosslinking agent for the binder. As the crosslinking agent, an inorganic or organic one known in the field of photographic materials can be used. For example, aldehyde compounds such as formaldehyde, glyoxal, glutaraldehyde,
Ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea) -2-hydroxy-
4,6-dichloro-1,3,5 triazine, a compound having a reactive halogen as described in U.S. Pat. No. 3,288,775, divinyl sulfone, U.S. Pat. No. 3,635,718.
Compounds having a reactive olefin as described in U.S. Pat. No. 3,732,316, N-methylol compounds as described in U.S. Pat. No. 2,732,316, isocyanates as described in U.S. Pat. No. 3,103,437, U.S. Pat.
Aziridine compounds as described in No. 11, US Pat.
Carbodiimide compounds as described in No. 0070, epoxy compounds as described in US Pat. No. 3,091,537,
Halogen carboxaldehydes such as mucochloric acid,
There are dioxane derivatives such as dihydroxydioxane, chromium alum, potassium alum, zirconium sulfate, boric acid, inorganic hardeners such as borax, and the like.
It can be used in combination of more than one kind. In particular, when polyvinyl alcohol is used as a binder, glyoxal, boric acid, and borax are preferred. The amount of the crosslinking agent added is preferably 0.5% by weight or more, more preferably 0.5 to 5% by weight, based on the water-soluble binder.

In the present invention, as the water-soluble polymer used for the lower layer, 5
Any polymer that dissolves in an amount of at least 1% by weight can be used, but taking into account the ink absorbency, one or more of gelatin, polyvinylpyrrolidone, a water-soluble cellulose derivative, polyvinyl alcohol, polyacrylamide, and polyacrylic acid can be used. It is preferable to use a combination of functional polymers. In particular, it is preferable to use gelatin and another water-soluble polymer (eg, polyvinylpyrrolidone, carboxymethylcellulose, etc.) in combination.

Among the above water-soluble polymers, gelatin is particularly preferably used. As the gelatin, any gelatin can be used as long as it is made from animal collagen, but gelatin made from collagen made from pork skin, cow skin and bovine bone is preferred. Further, the kind of gelatin is not particularly limited, but lime-treated gelatin, acid-treated gelatin, gelatin derivatives (for example, Japanese Patent Publication No. 38-4854).
No. 39-5514, No. 40-12237,
No. 42-26345, U.S. Pat. No. 2,525,753
No. 2594293, No. 2614928, No. 2763639, No. 3118766, No. 31
No. 32945, No. 3186846, No. 33125
No. 53, British Patent Nos. 861414 and 103318
No. 9, etc.) alone or in combination. Further, the jelly strength of the gelatin (based on the PAGI method and the bloom jelly strength meter) is preferably 150 g or more, particularly preferably 200 g or more.

In the present invention, among the water-soluble polymers other than gelatin, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl alcohol, polyacrylamide and polyacrylic acid are most preferably used as the water-soluble vinyl polymer.
Vinyl formal such as various modified polyvinyl alcohols and derivatives thereof (JP-A-60-145879,
Nos. 0-220750, 61-143177, 61-235182, 61-235183, 61-237681, and 61-26089), polydimethylacrylamide, polydimethylaminoacrylate , Acrylic acid methacrylic acid copolymer salt,
Polymers containing acrylic groups such as polysodium methacrylate and vinyl acrylate copolymer salts
Nos. 168,651 and 62-9988), polyethylene glycol, polypropylene glycol, polyvinyl ether (JP-A-61-32787, JP-A-61-1987).
-237680 and 61-277483) are also preferably used.

In the present invention, water-soluble cellulose derivatives preferably used include methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose,
Water-soluble cellulose derivatives such as hydroxyethyl cellulose and hydroxypropyl cellulose can be mentioned. Among these water-soluble cellulose derivatives, carboxymethylcellulose, hydroxyethylcellulose, and methylcellulose are more preferable from the viewpoints of ink receptivity, dot reproducibility and prevention of stickiness of a printed portion.

In the present invention, the lower layer containing the water-soluble polymer preferably contains an aliphatic carboxylic acid having 4 or less carbon atoms (excluding the carbon number of the carboxyl group). This further improves the ink absorbency. Among the above carboxylic acids, dicarboxylic acids or tricarboxylic acids are particularly preferred, and examples thereof include malonic acid, succinic acid, malic acid, tartaric acid, and citric acid. The content of these carboxylic acids is 1% by weight or more, preferably 3 to 20% by weight, based on the water-soluble polymer.

In the lower layer, together with a water-soluble polymer, inorganic pigments such as amorphous porous silica, calcium carbonate, talc, clay, kaolin, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, aluminum silicate, magnesium silicate and calcium silicate; Colloidal inorganic fine particles such as colloidal silica and colloidal alumina, and thermosetting organic resin particles may be appropriately added. The lower layer may further contain the above-mentioned hardener, but it is preferable not to substantially contain the same in consideration of ink absorbency. Even if you include
0.5% by weight or less based on the water-soluble polymer.

In the present invention, a surfactant can be added to the upper layer containing fumed silica or the lower layer containing a water-soluble polymer. 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 liquid. 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 g to 5 g, more preferably 0.01 to 3 g, per 100 g of the binder constituting the ink receiving layer.

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

In the present invention, the lower layer and the upper layer may be coated simultaneously, or the lower layer may be coated and dried, and then the upper layer may be coated and dried. The application method in that case is not particularly limited,
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.

The lower layer containing the water-soluble polymer and the upper layer containing the fumed silica are dried after coating by a so-called cold drying method in which the gel is once brought into a gel state and then dried at a low temperature. preferable. This uses the sol and gelation phenomena of gelatin to form a uniform film surface.
It is a method of drying at low temperature. The drying process is described in "Coating Engineering" by Yuji Harasaki (1976, Asakura Shoten), 2
Material preheating period as described on pages 78-281,
The evaporation amount of the solvent per unit time, that is, the constant-rate drying period of the drying process in which the evaporation rate of the solvent is constant, and thereafter, the evaporation rate of the solvent gradually decreases, and almost no vapor is generated (that is, the coating film is almost completely evaporated). 3) of reduced drying period of the drying process up to the equilibrium moisture content under hot and humid conditions of the outside air.
The process is divided into two processes, and if necessary, a humidity control period may be provided. Usually, drying is completed when the equilibrium water content of about 5 to 8% is reached. However, if the temperature of the film surface during the drying process (this temperature is referred to as surface wet bulb temperature) is lowered, a uniform coating film is obtained. And a high quality ink receiving layer is obtained. After applying the ink receiving layer coating solution, the coating layer is cooled and set (gelled) when the surface wet bulb temperature is below the gelling temperature of the coating solution, and then the receiving layer is gradually cooled at a temperature below the gelling temperature of the coating solution. To dry. After the solvent evaporates and the solids concentration increases, the temperature may be raised to such an extent that set return does not occur, followed by drying.

In the present invention, the ink recording sheet has at least two layers of an upper layer containing fumed silica and a lower layer containing a water-soluble polymer, and further includes an ink absorbing layer, an ink fixing layer, an intermediate layer, and a protective layer. May be provided.

The support used in the present invention is preferably a waterproof support. As the waterproof 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 of celluloid and the like 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 waterproof support preferably has a thickness of about 10 to 200 μm.

As the opaque waterproof support, synthetic paper,
Any conventionally known materials such as resin-coated paper, opaque film containing pigment, and foam 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 waterproof 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 a pressure by a calender or the like during or after paper making, and has a basis weight of 30 to 250 g / 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.
Examples of the polyolefin resin are 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, arachidic amide, zinc stearate, calcium stearate, stearic acid 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 a heated and melted resin is cast on a running base paper in the case of a polyolefin resin. 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 favorably. 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, if necessary, both front and back surfaces can be subjected to an activation treatment such as a corona discharge treatment or a flame treatment. The thickness of the coating resin 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 may 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.

[0050]

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

On the above support, the following lower layer coating solution was applied and dried, and then the upper layer coating solution was applied and dried to prepare various ink jet recording sheets. Various recording sheets were prepared as shown in Table 1 for the type and amount of the water-soluble polymer and the type and amount of the inorganic fine particles.

<Lower Layer> Water (adjusted to have a solid content of 5% by weight) Water-soluble polymer Xg / m ² Di-2-ethylhexyl sodium sulfosuccinate 0.2 g / m ²

<Upper layer> Water (adjusted to have a solid content of 10% by weight) Inorganic fine particles Yg / m ² polyhydrinyl alcohol (average degree of polymerization: 3500, saponification degree: 88%) 20% by weight of Y di-2- Sodium ethylhexyl sulfosuccinate 0.2 g / m ²

[0055]

[Table 1]

Further, as a comparative example, Comparative Example 7 in which the lower layer of the present invention 1 was applied to the upper layer and the upper layer was applied to the lower layer in reverse was applied. These 10 types of recording sheets were tested for ink absorption capacity, drying property, and glossiness using an inkjet printer (MJ930 manufactured by Epson Corporation) in the following manner. Table 2 shows the results.

<Ink Absorption Capacity> The state of ink overflow at the time of discharging 100% of the maximum ink amount of each of the Y, M, C, and K inks was visually observed and evaluated according to the following criteria. A: No overflow at all immediately after printing. ：: Slight overflow immediately after printing, but absorbed within about 10 seconds. Δ: overflowed immediately after printing and absorbed within about 20 seconds. ×: overflowing immediately after printing, it takes 30 seconds or more to absorb.

<Dryability> After printing under the above conditions, after a certain period of time, plain paper was overlaid and allowed to stand, and the time until ink no longer transferred to plain paper was measured and evaluated according to the following criteria. ◎: Within 2 minutes ○: 2 to 4 minutes △: 4 to 6 minutes ×: 6 minutes or more

<Gloss> Specular gloss measurement method (JIS-
Z8741) was measured using a gloss meter (VGS-1D manufactured by Nippon Denshoku Industries Co., Ltd.).

[0060]

[Table 2]

From the above results, it is understood that the recording sheet of the present invention has a large ink absorption capacity and is excellent in drying property and glossiness.

Example 2 A fumed silica having an average primary particle diameter of 7 nm or a fumed silica having an average primary particle diameter of 20 nm was used in place of the fumed silica A used for the recording sheet of the present invention 2 in Example 1. Two kinds of recording sheets of the present invention were prepared in the same manner as the recording sheet of the present invention 2 except that the method silica was used. As a result of a test performed in the same manner as in Example 1, the same results as those of the recording sheet of the second embodiment were obtained for each of the two types of recording sheets.

Example 3 In place of the gelatin used for the recording sheet of the present invention 2 in Example 1, (1) 5 g / m ^{2 of} polyvinylpyrrolidone (2) 5 g / m ^{2 of} carboxymethylcellulose (3) Gelatin the 5 g / m ² and polyvinyl pyrrolidone 2.5g / m ² (4) gelatin 2.5 g / m ² and carboxymethylcellulose 2.5 g / m ^2, except for using each in the same manner as the recording sheet of the present invention 2, the Four types of recording sheets of the invention were made. Example 1
As a result of the same test as described above, all the four types of recording sheets obtained the same results as the recording sheet of the second embodiment.

Example 4 According to Example 1, recording sheets of the present invention as shown in Table 3 were prepared.

[0065]

[Table 3]

The recording sheet prepared by the above-described method was used with an ink jet plotter (Novajet PRO, GA ink manufactured by Encad) having a maximum ink amount of 90% of the maximum ink amount of each of the Y, M, C and K inks. %, And the ink absorption capacity, drying property, and glossiness were evaluated in the same manner as in Example 1. Table 4 shows the results.

[0067]

[Table 4]

From the above results, (A × 2) + (B × 8) ≧
It can be seen that by setting the layer configuration to satisfy 40, it can be sufficiently applied to a plotter having a larger amount of ink. Particularly, by satisfying (A × 2) + (B × 8) ≧ 50, an even greater effect can be obtained.

Example 5 In the same manner as in Example 4, except that 10% by weight of succinic acid or 5% by weight of malic acid was added to the lower layer of the recording sheets of the present invention 4 to 9 according to the present invention. ~
21 recording sheets were created. These recording sheets were printed with 100% ejection of the maximum ink amount of each of the Y, M, C, and K inks using an ink-jet plotter with a large amount of ink (Novajet PRO, GA ink manufactured by Encad), and ink absorption was performed. The capacity, drying property and glossiness were evaluated in the same manner as in Example 1. Table 5 shows the results.

[0070]

[Table 5]

From the above results, it can be seen that the lower water-soluble polymer layer containing an aliphatic carboxylic acid having 4 or less carbon atoms, such as succinic acid and malic acid, can sufficiently cope with a further increase in the ink ejection amount. I understand.

Example 6 The same procedure as in Example 9 was repeated except that boric acid or glyoxal as a crosslinking agent was added to the upper layer of the recording sheet of Example 9 in an amount of 1% by weight based on polyvinyl alcohol. Recording sheets 22 and 23 were prepared. Example 4
The ink absorption capacity, drying property and glossiness were evaluated in the same manner as in the above. As a result, the ink absorbing capacity and the drying property of the recording sheets of the present inventions 22 and 23 are almost the same as those of the present invention 9;
The gloss increased by a further 5%. This increase in gloss is due to the inclusion of a hardener in the upper layer, which prevented the generation of minute cracks due to distortion of the upper layer due to swelling of the lower layer during ink absorption.

[0073]

According to the ink jet recording sheet of the present invention, the ink absorption capacity, drying property and glossiness can be simultaneously satisfied. Particularly, it is suitably used for a high-speed plotter having a large amount of ink. By including a specific carboxylic acid together with the water-soluble polymer in the lower layer, the ink absorption capacity and the drying property are further improved. In addition, by including a binder and a crosslinking agent thereof together with fumed silica in the upper layer, fine cracks can be prevented and the gloss can be further improved.

Claims (4)

[Claims] 1. A water-soluble polymer is added from the side closer to the support.
g / m ² or more containing layer and primary particles having an average particle size of 50 nm
An ink jet recording sheet having at least a layer containing 5 g / m ² or more of synthetic silica obtained by the following gas phase method. 2. The ink jet recording sheet according to claim 1, wherein the layer containing the water-soluble polymer and the layer containing the fumed silica satisfy the following conditional expression 1. Conditional expression 1 (A × 2) + (B × 8) ≧ 40 In the formula, A represents the content per 1 m ^{2 of the} silica synthesized by the gas phase method, and B represents the content per 1 m ^{2 of the} water-soluble polymer. Indicates weight. 3. The ink jet recording sheet according to claim 1, wherein the layer containing the silica synthesized by the gas phase method contains a binder and a crosslinking agent thereof. 4. The ink jet recording sheet according to claim 1, wherein the layer containing the water-soluble polymer contains an aliphatic carboxylic acid having 4 or less carbon atoms.