JPH07179026A - Ink jet recording sheet - Google Patents

Abstract

PURPOSE:To provide an ink jet recording sheet having no crack on the surface of an ink receiving layer, having high glossiness, excellent in ink absorbability and good in dot reproducibility. CONSTITUTION:In an ink jet recording sheet, the ink receiving layer thereof is formed from a coating soln. mainly containing inorg. fine particles with an average particle size of below 0.1mum and a binder and further containing a water-soluble org. solvent with a b.p. of 120 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording sheet on which an image is formed by an inkjet printer. More specifically, the present invention relates to an inkjet recording sheet which has no cracks on the surface of the ink receiving layer, has high gloss, is excellent in ink absorbency, and has good dot reproducibility.

[0002]

2. Description of the Related Art Ink jet recording is a system in which minute droplets of ink are ejected by various operating principles and adhered to a recording sheet such as paper to record images, characters and the like. Inkjet printers have features such as high-speed printing, low noise, high flexibility in recording patterns, and no need for development-fixing, so that complex images can be formed accurately and quickly. In recent years, it has been rapidly popularized for various purposes, especially as a hard copy creating apparatus for image information such as characters and various figures created by a computer.

Further, in the ink jet recording method, it is easy to perform multicolor recording by using a plurality of ink nozzles. In the multicolor inkjet recording system,
Compared to multicolor printed matter and color photographs, it is possible to obtain an image that is comparable to that of multicolored printed matters and color photographs. Further, in applications where the number of copies is small, it is cheaper than printing technology and photographic technology, and is therefore being widely used.

In recent years, the fields of use of ink jet printers, which have received a great deal of attention, include the production of color proofs and the output of design images in the design field in the printing field where high image quality close to that of photographs is required. Furthermore, it is also common practice to output characters and image information created by a computer to a transparent recording sheet using an inkjet printer and use this as an original for an overhead projector for presentations at conferences.

The characteristics required for the recording sheet used in such an ink jet recording system are that the surface of the ink receiving layer has a high gloss, the image density is high, the color reproducibility is good, and the ink absorbability is high. And high dot reproducibility.

As a conventionally known technique, for example, Japanese Patent Publication Sho
61-60793, JP 3-215081 JP, etc., silica,
An inkjet recording sheet having an ink receiving layer composed of an inorganic pigment such as colloidal silica, alumina sol and calcium carbonate and a water-soluble binder such as oxidized starch, polyvinyl alcohol, carboxymethyl cellulose and polyacrylic acid is disclosed. However, the above-mentioned inkjet recording sheet was not always at a level where the gloss, dot reproducibility, and ink absorbency of the surface of the ink receiving layer were satisfactory.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a surface having no cracks on the ink-receiving layer, which has high gloss, excellent ink absorbability, and good dot reproducibility, which could not be realized by conventional techniques. Another object of the invention is to provide an inkjet recording sheet.

[0008]

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, the coating liquid for the ink-receiving layer mainly contains inorganic fine particles having an average particle diameter in a specific range. When containing a binder and a water-soluble organic solvent having a boiling point in a specific range, there is no crack on the surface of the ink receiving layer, it has high gloss, and it has excellent ink absorbability,
Moreover, they found that the dot reproducibility was good, and completed the present invention.

That is, the ink jet recording sheet of the present invention is an ink jet recording sheet in which an ink receiving layer is provided on a support, and the coating liquid for the ink receiving layer is mainly composed of inorganic fine particles having an average particle diameter of less than 0.1 μm and a binder. And a water-soluble organic solvent having a boiling point of 120 ° C. or higher.

In the ink jet recording sheet of the present invention, the amount of the water-soluble organic solvent added is such that the inorganic fine particles 10
It is characterized in that it is 300 parts by weight or less with respect to 0 parts by weight.

The average particle size of the inorganic fine particles used in the ink receiving layer coating liquid of the present invention is preferably less than 0.1 μm. When the average particle diameter is 0.1 μm or more, the gloss of the surface of the ink receiving layer decreases, which is not preferable. Examples of such inorganic fine particles include colloidal silica, alumina sol, fine particle titanium oxide, and fine particle zinc oxide.

Examples of the binder used in the coating liquid for the ink receiving layer of the present invention include the following polymers. Various kinds of gelatin such as lime-processed gelatin, acid-processed gelatin, enzyme-processed gelatin, gelatin derivatives (eg, gelatin reacted with an anhydride of dibasic acid such as phthalic acid, maleic acid and fumaric acid), polyvinyl alcohol with various saponification degrees ,
Carboxy-modified, cation-modified and amphoteric polyvinyl alcohols or their derivatives, starches such as oxidized starch, cationized starch and etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, polyvinylpyrrolidone, polyvinylpyridinium Halide, sodium polyacrylate, acrylic acid methacrylic acid copolymer salt, polyethylene glycol, polypropylene glycol, polyvinyl ether, alkyl vinyl ether / maleic anhydride copolymer, styrene / maleic anhydride copolymer or salts thereof, polyethyleneimine Synthetic polymers such as styrene / butadiene copolymers, methyl methacrylate / butadiene copolymers / conjugated diene copolymer latex, polyvinyl acetate, vinyl acetate / maleic acid S Copolymer, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer and other vinyl acetate polymer latex, acrylic acid ester polymer, methacrylic acid ester polymer, ethylene / acrylic acid ester copolymer Acrylic polymer or copolymer latex such as polymer, styrene / acrylic acid ester copolymer, vinylidene chloride copolymer latex, etc. or various functional group-containing monomers such as carboxyl groups of these polymers Functional group-modified polymer latex, water-based adhesive such as thermosetting synthetic resin such as melamine resin, urea resin and polymethylmethacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride / vinyl acetate copolymer, polyvinyl butyral, alkyd resin Polymers such as synthetic resin adhesives are used alone or in combination. It can be incorporated.

The addition amount of these binders is preferably such that the solid content weight ratio of the inorganic fine particles to the binder is in the range of 20/1 to 5/1.

The water-soluble organic solvent added to the coating liquid for the ink-receiving layer of the present invention means one having a solubility in water of 10% or more. If the solubility is less than 10%, repelling may occur during coating and the gloss of the ink receiving layer may decrease due to layer separation, which is not preferable.

The boiling point of the water-soluble organic solvent is preferably 120 ° C. or higher. When the boiling point is lower than 120 ° C., the surface of the ink receiving layer is easily cracked, the gloss is lowered, the dot reproducibility is deteriorated, and an image with high sharpness cannot be obtained, which is not preferable.

The amount of the water-soluble organic solvent added is preferably 300 parts by weight or less based on 100 parts by weight of the inorganic fine particles. When the amount of the water-soluble organic solvent added exceeds 300 parts by weight, blocking on the surface of the ink receiving layer and image bleeding occur, which is not preferable.

Examples of the water-soluble organic solvent having a boiling point of 120 ° C. or higher include polyhydric alcohols such as ethylene glycol, methyl cellosolve and glycerin and their derivatives, ketones such as acetonylacetone and diacetone alcohol, amyl formate and the like. Examples thereof include esters, fatty acids such as butyric acid and monochloroacetic acid, amines such as propylenediamine and diethylenetriamine, acid amides such as formamide and N, N-dimethylformamide, and sulfur compounds such as dimethylsulfoxide.

In the present invention, the ink receiving layer coating liquid comprises
Inorganic fine particles having an average particle size of less than 0.1 μm, a binder, and a water-soluble organic solvent having a boiling point of 120 ° C. or more, if necessary, a pigment, a hardener, a surfactant, an antiseptic, a dye, an ultraviolet absorber, an oxidant. Various additives such as an inhibitor, a pencil writing agent, a pH adjusting agent, and a defoaming agent can be added.

Examples of pigments include inorganic particles such as silica, magnesium carbonate, calcium carbonate, titanium oxide and zinc oxide. The addition amount of these pigments does not reduce the gloss of the ink receiving layer, so the average particle size is 0.1 μm.
20 with respect to 100 parts by weight of solid content of inorganic fine particles of less than m
It is preferably less than or equal to parts by weight.

Other various additives include active halogen compounds, vinyl sulfone compounds, aziridine compounds, epoxy compounds, acryloyl compounds, isocyanate compounds, and other hardening agents, anionic, cationic, nonionic, betaine-based, and fluorine-based additives. Surfactants such as. Kohei
Preservatives such as p-hydroxybenzoic acid ester compounds, benzisothiazolone compounds and isothiazolone compounds described in JP-A 1-102551, JP-A-63-204251 and JP-A-1-
UV absorbers such as benzotriazole compounds having a hydroxy-di-alkylphenyl group at the 2-position, such as colored pigments, colored dyes and fluorescent dyes described in JP-A-266537.
JP-A 1-105245, antioxidants such as hindered phenol compounds, and pencil writing agents, caustic soda and sodium carbonate, which consist of fine particles of organic or inorganic particles having a particle size of 0.2 to 5 μm, such as starch particles, barium sulfate and silica. A pH adjusting agent such as sulfuric acid, hydrochloric acid, phosphoric acid, or citric acid, and a defoaming agent such as silicon can be appropriately combined and added.

In the present invention, the dry coating amount of the ink receiving layer is preferably ¹ to 50 g / m ² . When the coating amount of the ink receiving layer is less than 1 g / m ² , the ink receiving property is poor, so that the ink overflows from the ink receiving layer after printing, and the image is liable to be mixed due to color mixing or rubbing. On the other hand, if it exceeds 50 g / m ² , problems such as deterioration of image resolution due to ink sinking and curling of the recording sheet occur.

In the present invention, as a coating method of the ink receiving layer coating liquid, a rod system, a wire bar system, a slide hopper system, a curtain system, an extrusion die system, an air knife system, a roll system, a blade system, etc. are generally used. Conventional coating method is used.

In the present invention, the ink receiving layer may be either a single layer or a multilayer of two or more layers. In the case of multiple layers, each layer may have a different composition or the same composition. When forming multiple layers, two or more layers may be coated at once or one layer at a time.

In the present invention, the ink receiving layer is provided on at least one side of the support, but it may be provided on both sides of the support for the purpose of performing double-sided printing or preventing curling.

In the present invention, as the support, paper, film, metal foil, synthetic paper, cloth, non-woven fabric or a composite thereof can be used. From the viewpoint of image quality, gloss, smoothness, etc., a polyolefin resin coating is used. The use of paper or film is preferred.

The thickness of the support is not particularly limited, but it is 50 because of its handleability and suitability for passing paper through the printer.
It is preferably about 300 μm.

The support of the present invention may be provided with an undercoat layer before the ink receiving layer is provided in order to improve the coatability of the ink receiving layer coating liquid. Such an undercoat layer contains a pigment, various water-soluble polymers,
A latex, a hardener, a surfactant and the like can be added in an appropriate combination.

The support in the present invention has an antistatic property,
A back coat layer may be provided in order to impart transportability, curl prevention property, and the like. An inorganic or organic antistatic agent, a water-soluble binder, a synthetic resin latex, a hardener, a pigment, a surfactant and the like can be added to such a back coat layer in an appropriate combination.

[0029]

According to the present invention, when the ink receiving layer coating liquid contains mainly inorganic fine particles having an average particle size of less than 0.1 μm and a binder and also contains a water-soluble organic solvent having a boiling point of 120 ° C. or higher, Since the solvent has a higher boiling point than water, evaporation of the water-soluble organic solvent is delayed compared to water, and it is possible to suppress cracking of the ink receiving layer surface due to increase in surface tension when water is evaporated, It is possible to obtain an inkjet recording sheet that can maintain high gloss, is excellent in ink absorption, and has good dot reproducibility.

[0030]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In addition,
All "parts" and "%" described in the following examples are weight conversion values.

Example 1 On the surface of a base paper made of LBKP and having a basis weight of 100 g / m ² ,
After the corona discharge treatment, 1% of a resin composition containing 85% by weight of low-density polyethylene and 15% by weight of titanium dioxide was used.
6 g / m ^{2 was} coated, and similarly on the back side, a resin composition comprising 60% by weight of high-density polyethylene and 40% by weight of low-density polyethylene was coated at 16 g / m ² to prepare a polyolefin resin-coated paper. . After subjecting the surface of the resin-coated paper to corona discharge treatment, an ink-receiving layer coating liquid having the following composition was applied and dried so that the dry coating amount was 25 g / m ² , and an inkjet recording sheet was produced. <Ink receiving layer formulation 1> Colloidal silica (average particle diameter 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part Methyl cellosolve (boiling point 124. 4 ° C) 100 parts

Example 2 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 2> Colloidal silica (average particle diameter 0.01 μm) 100 parts Polyvinyl alcohol (PVA117, manufactured by Kuraray) 10 parts Surfactant (TRF K-40, manufactured by NOF Corporation) 1 part DMF (boiling point 149.56) ℃) 100 parts

Example 3 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 3> Colloidal silica (average particle diameter 0.01 μm) 100 parts Polyvinyl alcohol (PVA117, manufactured by Kuraray) 10 parts Surfactant (TRAX K-40, manufactured by NOF Corporation) 1 part Ethylene glycol (boiling point 197. 2 ℃) 100 parts

Example 4 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 4> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part Glycerin (boiling point 290 ° C.) 100 copies

Example 5 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 5> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 300 parts

Example 6 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 6> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (Nippon Oil & Fat, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 350 parts

Example 7 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 7> Colloidal silica (average particle size 0.08 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 100 parts

Example 8 An ink jet recording sheet was prepared in the same manner as in Example 1 except that the ink receiving layer coating liquid was changed to the following composition. <Ink receiving layer formulation 8> Colloidal silica (average particle diameter 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 3 parts Surfactant (Nippon Oil & Fat, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 100 parts

Example 9 An ink jet recording sheet was prepared in the same manner as in Example 1 except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 9> Colloidal silica (average particle diameter 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 5 parts Surfactant (NOF Corporation, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 100 parts

Example 10 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 10> Colloidal silica (average particle diameter 0.01 μm) 100 parts Polyvinyl alcohol (PVA117 manufactured by Kuraray) 20 parts Surfactant (Nippon Oil & Fat, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 100 parts

Example 11 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 11> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (PVA117, manufactured by Kuraray) 30 parts Surfactant (NOF Corporation, Trax K-40) 1 part Ethylene glycol (boiling point 197. 2 ℃) 100 parts

Example 12 In Example 2, the support was LBKP 70% and NBKP.
An ink jet recording sheet was produced in exactly the same manner except that the high-quality paper having a basis weight of 100 g / m ² of 30% was used.

Example 13 An ink jet recording sheet was prepared in the same manner as in Example 2 except that the support was changed to a white polyethylene terephthalate film having a thickness of 100 μm.

Example 14 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 12> Alumina sol (average particle diameter 0.06 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (Nippon Oil & Fat, Trax K-40) 1 part Ethylene glycol (boiling point 197.2) ℃) 100 parts

Comparative Example 1 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the ink receiving layer coating liquid was changed to the following composition. <Ink receiving layer formulation 13> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part

Comparative Example 2 An ink jet recording sheet was prepared in the same manner as in Example 1 except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 14> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part Monopropylene glycol methyl ether ( Boiling point 119 ° C) 100 parts

Comparative Example 3 An inkjet recording sheet was prepared in the same manner as in Example 1, except that the coating liquid for the ink receiving layer was changed to the following composition. <Ink receiving layer formulation 15> Colloidal silica (average particle size 0.01 μm) 100 parts Polyvinyl alcohol (Kuraray, PVA117) 10 parts Surfactant (NOF Corporation, Trax K-40) 1 part Ethyl alcohol (boiling point 78. 2 ℃) 100 parts

Comparative Example 4 An ink jet recording sheet was prepared in the same manner as in Example 1, except that the ink receiving layer coating liquid was changed to the following composition. <Ink receiving layer formulation 16> Colloidal silica (average particle size 0.12 μm) 100 parts Polyvinyl alcohol (PVA117, manufactured by Kuraray) 10 parts Surfactant (Nippon Oil & Fat, Trax K-40) 1 part Ethylene glycol (boiling point 197. 85 ° C) 100 parts

Examples 1 to 12 obtained as described above
The inkjet recording sheets of Comparative Examples 1 to 6 were printed using a Desk Writer 550C printer manufactured by Hewlett Packard, and the printed images were evaluated as follows. The results are shown in Table 1.

Evaluation Method: (Glossiness) The glossiness of the image area and non-image area of the ink jet recording sheet was visually determined.

(Crack) The cracked state of the surface of the ink jet recording sheet was visually judged.

(Dot reproducibility) The ink jet recording image is observed with a microscope to visually determine the diameter and shape of the dot.
It was determined whether the dot diameter was too large or the shape was close to a perfect circle.

(Ink absorbency) Five minutes after printing, the image area was rubbed with a finger to evaluate ink absorbency.

(Blocking resistance) An unprinted ink jet recording sheet was touched with a finger to evaluate blocking resistance (stickiness resistance).

The evaluation criteria of the above quality test are as follows: ○: good,
Δ: Within practical limit, ×: Inferior.

[0056]

[Table 1]

As is clear from the results shown in Table 1, Examples 1 to 1
In the inkjet recording sheet of No. 14, since the coating liquid for the ink receiving layer mainly contained the inorganic fine particles having an average particle size of less than 0.1 μm and the binder and also contained the water-soluble organic solvent having a boiling point of 120 ° C. or more, there was no cracking. Glossy,
The dot reproducibility and ink absorbency were also good. On the other hand, in the ink jet recording sheet of Comparative Example 1, the coating liquid for the ink receiving layer did not contain a water-soluble organic solvent having a boiling point of 120 ° C. or more, so cracks increased, gloss decreased, and dot reproducibility deteriorated. did. In the ink jet recording sheets of Comparative Examples 2 and 3, the ink receiving layer coating liquid has a boiling point of 120.
Since it contained a water-soluble organic solvent having a temperature of less than 0 ° C, it had many cracks, reduced gloss, and deteriorated dot reproducibility. In the inkjet recording sheet of Comparative Example 4, the coating liquid for the ink-receiving layer contained an inorganic pigment having an average particle diameter of 0.1 μm or more, so that the gloss was lowered.

[0058]

According to the present invention, it is possible to obtain an ink jet recording sheet having no cracks on the surface of the ink receiving layer, high glossiness, excellent ink absorbability and good dot reproducibility.

Claims (2)

[Claims] 1. An ink jet recording sheet having an ink receiving layer provided on a support, wherein the ink receiving layer coating liquid comprises
An ink jet recording sheet comprising mainly inorganic fine particles having an average particle diameter of less than 0.1 μm and a binder, and a water-soluble organic solvent having a boiling point of 120 ° C. or more. 2. The ink jet recording sheet according to claim 1, wherein the amount of the water-soluble organic solvent added is 300 parts by weight or less based on 100 parts by weight of the inorganic fine particles.