JP2000238422A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve glossiness, ink-absorbing speed and an ink-absorbing volume and to eliminate a subdued image by incorporating a vapor phase silica having a specific surface area by a BET method exceeding a specific value or above in an ink receiving layer. SOLUTION: As a content of a vapor phase silica existing in a secondarily aggregating state and having a specific surface area by a BET method exceeding 300 m2/g so that primary particles are connected to each other in a network structure or chain-like state in an ink receiving layer, a range of about 10 to 30 g/m2 is best. The receiving layer containing the silica has high transparency due to maintaining of characteristic as a film. As the receiving layer, use of a completely or partially saponified polyvinyl alcohol or cationic modified polyvinyl alcohol of a hydrophilic binder capable of obtaining higher permeability of an ink is good. In the receiving layer, a dispersion stabilizer for improving glossiness and ink absorbency, a film-hardener for preventing an air gap disturbance of the receiving layer in the case of printing or the like can be used.

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 high gloss, high ink absorption speed and high ink absorption capacity and free from image dullness.

[0002]

2. Description of the Related Art As a recording sheet 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 sheet by a porous binder made of a hydrophilic binder such as polyvinyl alcohol. A recording sheet provided with a high quality ink absorbing layer is known.

[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
No. 82, 64-11877, etc., 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.

Further, the use of synthetic silica fine particles by a gas phase method (hereinafter referred to as gas phase silica) is disclosed in
No. 56552, JP-A-2-113986, JP-A-2-1-1
No. 88287, No. 7-276789, No. 8-34
No. 160, No. 8-132728, No. 8-1749
No. 92, No. 8-2698993, No. 9-28616
No. 1, same Hei 9-286162, same Hei 10-81064
No. 10-175365, 10-20300
No. 6, No. 10-217601, and Japanese Patent Publication No. 3-56552 describes the use of fumed silica having a specific surface area of 80 to 200 m ² / g. . By using the fumed silica of these fine particles, a technique of forming a layer (gap layer) having a large number of gaps in which the ink receiving layer absorbs and retains the ink, thereby further improving the ink absorbency of the recording sheet. Further, since fumed silica is fine particles, a glossy recording sheet with high glossiness can be easily obtained. However, conventional ink jet recording sheets using fumed silica are not sufficient in terms of ink absorption speed, ink absorption capacity, and image dullness, and further improvement is desired.

On the other hand, in the market for consumer printers and commercial large format plotters, the printing speed is remarkably improved, and the amount of ink ejected is increased in order to enhance the color development. ,
The required level of so-called ink absorbency has become higher. In particular, the ink absorption speed has been dramatically improved by remarkable development of hardware. Further, in digital photo applications using data obtained by a digital camera or the like, not only the ink absorbency but also the quality such as the sharpness of a printed image has become important. The sharpness of the image is affected by the dullness of the image, and particularly the dullness of the black print portion is important. Therefore, higher performance is required for the ink absorption speed, ink absorption capacity, and image dullness of the ink jet recording sheet.

[0006]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an ink jet recording sheet having high glossiness, high ink absorption speed and high ink absorption capacity and free from dull images.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide an ink jet recording sheet having at least one ink receiving layer on a support, wherein the ink receiving layer is B-type.
This is achieved by an ink jet recording sheet characterized by containing fumed silica having a specific surface area of at least 300 m ² / g by the ET method.

The inventors of the present invention have conducted intensive studies and have found that the use of fumed silica having a specific surface area of more than 300 m ² / g increases the thixotropic property of the coating solution, thereby making it possible to reduce the silica content during drying of the ink receiving layer. It has been found that the fine packing is disturbed and voids are easily formed, and as a result, the ink absorption speed and the ink absorption capacity are improved. In particular, it has been found that the effect of improving the ink absorption speed is high. Further, although the detailed reason is not clear, it has been found that the haze of the coating film is reduced by increasing the specific surface area, and it is further found that the dullness of the image is further improved.

[0009]

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 Silicic acid such as silica gel in which primary particles of several microns to 10 microns have become siloxane-bonded three-dimensional secondary particles, and those obtained by heating and producing silica sol, sodium silicate, sodium aluminate, etc. And the like.

The fumed silica used in the present invention 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 commercially available from Nippon Aerosil Co., Ltd. and Tokuyama Co., Ltd. and can be obtained.

The fumed silica used in the present invention is BE
The specific surface area according to the T method exceeds 300 m ² / g, whereby the ink absorption speed, the ink absorption capacity and the image dullness are improved. Above all, the effect of improving the ink absorption speed is high. A preferred embodiment of the present invention has a specific surface area of 33.
0 m ² / g or more, more preferably 350 m ² / g or more. The average primary particle size of the fumed silica having such a specific surface area is usually 15 nm or less, but is preferably 10 nm.
It is as follows.

As such a fumed silica, for example, a product name of Aerosil 38 manufactured by Nippon Aerosil Co., Ltd.
0, and product name: QS-40 from Tokuyama Corporation.

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 representing isotherms for multimolecular adsorption are Brunauer, Emmett,
This is the Teller's formula, called the BET formula, which is widely used for determining the surface area. The surface area is obtained by calculating the amount of adsorption based on the BET formula and multiplying the area occupied by one adsorbed molecule on the surface.

The most preferred embodiment of the present invention has a specific surface area of 3
Use of fumed silica having a particle size of 50 m ² / g or more and an average primary particle size of 10 nm or less.

A 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, whereby high ink absorption is obtained. The state of the secondary aggregation is preferably maintained at about 50 to 500 nm, whereby high ink absorbability can be obtained without reducing gloss. For this reason, it is preferable to add various dispersion stabilizers to the fumed silica solution in advance and treat the dispersion with a disperser such as a ball mill or a high-pressure homogenizer.

In the present invention, the amount of fumed silica contained in the ink receiving layer is preferably 8 g / m ² or more,
Range to 30 g / m ² is more preferable.

The ink receiving layer containing fumed silica is
It is preferable to have a binder in order to maintain the properties as a film. As the binder, various known binders can be used, but a hydrophilic binder which has high transparency and can obtain higher permeability of the ink is preferably used. 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.

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

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

Further, other hydrophilic binders can be used in combination, but 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.

In the ink receiving layer of the present invention, in addition to the fumed silica and the hydrophilic binder, a dispersion stabilizer for enhancing the dispersion stability of the fumed silica and improving the glossiness and the ink absorbability, and the ink jet ink. Primarily used are cationic polymers to improve the water resistance, light resistance, and high-humidity bleeding properties, and hardeners to prevent voids in the ink receiving layer due to swelling of the hydrophilic binder during printing. You.

As the dispersion stabilizer in the present invention, conventionally known inorganic and organic dispersion stabilizers can be used. As the organic dispersion stabilizer, various anionic, nonionic, and cationic dispersion stabilizers can be used, but preferably, a cationic dispersion stabilizer, and more preferably, a polydiallylamine derivative can be used. Specific examples of polydiallylamine derivatives include those containing a SO ₂ group in a repeating unit described in JP-A-60-83882, and JP-A-1-977.
No. 6, copolymers with acrylamide, and the like. The molecular weight of the cationic polymer of the polydiallylamine derivative used in the present invention is preferably 100,000 or less from the viewpoint of stabilizing the dispersion of fumed silica.
About 000-50,000 is more preferable.

The amount of the dispersion stabilizer used in the present invention is 1 to 10 parts, preferably 2 to 7 parts, per 100 parts of fumed silica. If the addition amount of the dispersion stabilizer to the fumed silica is more than the above range, the ink absorption of the ink receiving layer is reduced, and if the addition amount is too small, the dispersion stability of the fumed silica in the coating liquid is reduced. As a result, the gloss of the ink receiving layer after drying is reduced.

The method of adding the above-mentioned dispersion stabilizer in the process of producing the ink-receiving layer coating solution containing fumed silica may be such that fumed silica is dispersed in the presence of the dispersion stabilizer. You may add after dispersion | distribution of fumed silica. However, it is important to add it to the dispersion of fumed silica before adding a hydrophilic binder such as polyvinyl alcohol, and it is important to add it before adding another cationic polymer described below. . This improves the dispersion stability of the fumed silica. As described above, a generally known disperser such as a high-pressure homogenizer and a ball mill can be used for dispersing fumed silica.

In the present invention, as the cationic polymer used in the ink receiving layer, for example, at least one kind of a dicyandiamide derivative, a polyalkylene polyamine derivative, a polyamine derivative, a polyallylamine derivative and the like can be contained. Specifically, JP-A-60-4
No. 9990, No. 60-83882, No. 61-61
No. 887, No. 10-86508, No. 10-217
No. 601 can be mentioned.
The molecular weight of the cationic polymer is not particularly limited,
It is preferably 100,000 or less so as not to deteriorate the dispersibility of the fumed silica. By using the fumed silica of the present invention in combination with the cationic polymer, dullness of an image can be further prevented.

The amount of the cationic polymer used in the present invention is 0.5 to 30 per 100 parts of fumed silica.
Parts, preferably 1 to 10 parts. If the amount of the cationic polymer added to the fumed silica is more than the above range, the ink absorption of the ink receiving layer decreases, and if the amount is too small, the water resistance and high humidity bleeding of the recording sheet decrease.

The hardener used in the present invention includes aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, and bis (2-chloroethyl urea) -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, and a compound described in U.S. Pat. No. 3,635,718. A compound having a reactive olefin, an N-methylol compound as described in U.S. Pat. No. 2,732,316, and a U.S. Pat.
Isocyanates as described in U.S. Pat.
Aziridine compounds as described in US Pat. Nos. 017,280 and 2,983,611; carbodiimide-based compounds as described in U.S. Pat. No. 3,100,704;
No. 091,537, an epoxy compound, a halogen carboxaldehyde such as mucochloric acid, a dioxane derivative such as dihydroxydioxane, an inorganic hardener such as chrome alum, zirconium sulfate, boric acid and borate. Although it can be used in combination of two or more kinds, boric acid and boric acid are particularly preferable. The addition amount of the hardener is preferably 0.01 to 10 g, more preferably 0.1 to 5 g, per 100 g of the water-soluble polymer constituting the ink receiving layer.

The ink receiving layer in the present invention preferably contains various oil droplets in order to improve the brittleness of the film. Such oil droplets have a solubility in water at room temperature of 0.01% by weight. Polymerization of the following hydrophobic high-boiling organic solvents (eg, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicon oil, etc.) and polymer particles (eg, styrene, butyl acrylate, divinylbenzene, butyl methacrylate, hydroxyethyl methacrylate, etc.) Particles obtained by polymerizing one or more reactive monomers). Such oil droplets are preferably 10 to 50% by weight with respect to the hydrophilic binder.
Can be used.

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, more preferably 0.01 to 3 g, per 100 g of the binder constituting the ink receiving layer.

In the present invention, the ink receiving layer further comprises a coloring dye, a coloring pigment, an ultraviolet absorber, an antioxidant, an antifoaming agent, a leveling agent, a preservative, a fluorescent whitening agent, a viscosity stabilizer,
Various known additives such as a pH adjuster, a silane or a titanium coupling agent can also be added.

In the present invention, the coating method is not particularly limited, and a known coating method can be used. For example,
There are a slide lip method, a curtain method, an extrusion method, an air knife method, a roll coating method, a ked bar coating method and the like.

In the present invention, one ink receiving layer is provided on the support, but an ink absorbing layer, an ink fixing layer, an intermediate layer, a protective layer and the like may be further provided.

Examples of the water-resistant support used in the present invention include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, polyvinyl chloride, polyimide resins, cellophane, and the like. Examples include a resin film such as celluloid, a support in which paper is coated (laminated) with a polyolefin resin such as polyethylene or polypropylene, and a glass plate.

These supports may be transparent or opaque. The thickness of the water-resistant support used in the present invention is preferably about 50 to 200 μm.

In the present invention, polyethylene terephthalate or polyolefin resin-coated paper is particularly preferred because the glossiness is further enhanced. Hereinafter, the polyolefin resin-coated paper will be described in detail.

The base paper constituting the polyolefin resin-coated paper is not particularly limited, and generally used paper can be used, but more preferably, smooth base paper used for a photographic support, for example, is used. 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. This base paper contains sizing agents, paper strength agents,
Additives such as fillers, antistatic agents, optical brighteners, dyes, etc. are compounded.

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, fatty acid metal salts 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-melted resin is cast on a running base paper, the both surfaces of which are made of 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 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 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.

[0043]

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 a support, 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) is applied to the surface of a 120 g / m ² base paper. And high-density polyethylene (50
Parts) and a low-density polyethylene (50 parts) resin coating paper prepared by applying 25 g / m ² .

An ink receiving layer having the following composition was applied to the support and dried to prepare a recording sheet. The applied amount of silica was 15 g / m ^{2 in} solid content. In addition, a part means a solid content weight part.

<Recording sheet 1> 100 parts of fumed silica (trade name: Aerosil 380, manufactured by Nippon Aerosil Co., Ltd., specific surface area by the BET method is 380 m ² / g) 4 parts of dispersion stabilizer (trade name: Sharol DC902P) , Daiichi Kogyo Seiyaku Co., Ltd.) Cationic polymer 4 parts (trade name: Jetfix 30, manufactured by Satoda Kako Co., Ltd.) Boric acid 6 parts Polyvinyl alcohol 23 parts (trade name: PVA235, manufactured by Kuraray Co., Ltd., Ken Degree of polymerization 88%, average degree of polymerization 3500) Amphoteric surfactant 0.3 part (trade name: SWAM AM-2150, manufactured by Nippon Surfactant)

<Recording Sheet 2> The Aerosil 380 of the recording sheet 1 was replaced with QS-40 (available from fumed silica).
It was prepared in the same manner except that the specific surface area was 380 m ² / g by the BET method manufactured by Tokuyama.

<Recording Sheet 3> Aerosil 380 of the recording sheet 1 was replaced with Aerosil 300 which is fumed silica.
(Nippon Aerosil Co., Ltd., specific surface area 30 by BET method)
0 m ² / g).

<Recording Sheet 4> The gas-phase silica of the recording sheet 1 is fine seal K41, which is wet silica.
(Manufactured by Tokuyama Corporation, specific surface area 330m ² / by BET method)
It was prepared in the same manner except that g) was replaced.

The following evaluations were made on the ink jet recording sheet coated with the above four ink receiving layers. Table 1 shows the results.

<Gloss> The gloss of the surface of the unprinted ink jet recording sheet was visually determined. ：: Very high gloss and good. X: Low gloss and poor appearance.

<Ink Absorption Speed> Solid blue printing was performed using PM-750C, an inkjet printer manufactured by Epson Corporation, and the unevenness of the printed portion was visually evaluated according to the following criteria. When the ink absorption speed is low, unevenness of the printing portion occurs. ：: No unevenness is observed at all. Δ: Unevenness is observed. X: Remarkable unevenness is observed.

<Ink Absorbing Capacity> Tri-color solid printing of cyan, magenta and yellow was performed with an ink jet printer PM-750C manufactured by Epson Corporation, and one minute later, PPC was pressed on the image area. After holding for a while, peel off
The degree of the ink transferred to the PPC was visually evaluated based on the following criteria. The more ink transferred, the worse the ink absorbency. ：: No ink transfer was observed. Δ: Ink transfer was observed. ×: Marked transfer of ink.

<Image Dullness> Tricolor solid printing of cyan, magenta, and yellow was performed using Deskjet 720C, an inkjet printer manufactured by HP, and the degree of dullness of the solid portion was visually evaluated according to the following criteria. If the solid portion of the triple color becomes dull, there is a tendency that the image becomes dull as a whole when the image is printed. ：: Good without dullness. Δ: Dullness is observed. X: The dullness is remarkable.

[0055]

[Table 1]

As is clear from the results shown in Table 1, the recording sheets 1 and 2 had a specific surface area of 300 m ² / g by the BET method.
By adding fumed silica in excess of the above, an ink jet recording sheet having high gloss, high ink absorption rate and high ink absorption capacity and free from image dullness was obtained. On the other hand, the recording sheet 3 has a specific surface area of 300 by the BET method.
Since fumed silica of m ² / g or less was used, the ink absorption speed and ink absorption capacity were reduced, and the image dullness was slightly recognized. The specific surface area of the recording sheet 4 measured by the BET method exceeds 300 m ² / g, but glossiness, ink absorption capacity and image dullness are reduced due to the use of wet silica.

[0057]

According to the present invention, glossiness, ink absorption speed,
An ink jet recording sheet having a high ink absorption capacity and free from dull images can be provided.

Continued on front page F-term (reference) 2H086 BA15 BA33 BA48 4D075 AC04 AC14 AC22 AC60 CA35 CB04 DA04 DB18 DB36 DC27 EA33 EB42 4F100 AA20D AA21B AA21H AK01D AK05B AK05C AK06B AK06C AK69 BA10 CA05 BA10 CA05 BA05 CA05 BA10 CA05 BA05 CA05BA10 BA05 CA05BA05BA05BA05D GB41 JD14 JN21 YY00D 4L055 AG18 AG64 AH02 AH37 AJ04 BE08 EA17 FA12 FA15 GA09

Claims (1)

[Claims] 1. An ink jet recording sheet having at least one ink receiving layer on a support, wherein the ink receiving layer has a specific surface area of 300 m ² / g by a BET method.
An ink jet recording sheet comprising a fumed silica in excess of the above.