JP2001146072A - Recording resin composition and recording sheet formed with image receiving layer made of it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording resin composition having excellent ink absorbability, blocking resistance and capable of improving surface gloss of an image receiving layer, clarity of a recording image, water resistance, weather resistance and color reproducibility in an obtained recording sheet and the sheet obtained from the composition. SOLUTION: The recording resin composition for forming a recording layer comprises (1) a cellulose derivative (A) of 1 to 30 wt.%, (2) a resin composition of 100 pts.wt. containing a good solvent (B) of the cellulose derivative of 70 to 99 wt.% (total sum of the both of 100 wt.%), (3) an organic acid (C) soluble in a good solvent (B) or a poor solvent (D) of the cellulose derivative of 0.1 to 20 pts.wt. and arbitrarily (4) a poor solvent (D) of the cellulose derivative of 0 to 150 pts.wt. The recording sheet formed with an image receiving layer made of the composition on a material to be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording resin composition and a recording sheet obtained by applying the same. More specifically, the present invention relates to a resin composition useful for ink jet recording having excellent ink absorbency and water resistance, and a recording sheet comprising the same.

[0002]

2. Description of the Related Art Ink-jet recording systems have been rapidly spreading in recent years because they can be easily converted to full color, have good printing quality, and are economical. Used in wide printers. In inkjet recording,
In order to prevent clogging of the ink ejection nozzles, inks having low drying properties are used, and water-based inks are generally used in terms of safety, recording suitability, and the like. The ink is ejected from the ejection head toward the recording sheet as small droplets, and the image receiving layer of the recording sheet, which is a recording medium, is required to quickly absorb the ink and record images and characters.

In the image receiving layer of a recording medium having a low ink absorption, the ink remains on the image receiving layer surface of the recording medium without drying and fixing for a long time even after the recording is completed. If the image receiving layer surface of the recording medium is overlapped with the recording medium, the recording portion is stained with ink that has not been dried and fixed, which is a practical problem. Further, in the high-density image area, a large amount of supplied ink is not absorbed, and there is a problem that the quality of recorded images and characters is deteriorated by mixing inks of each color, and the ink flows out on the surface of the image receiving layer of the recording medium. Was.

In order to improve these problems, some proposals have been made and implemented. For example, JP-A-59-174381, JP-A-60-2245
No. 78 proposes to use a hydrophilic polymer such as starch, a water-soluble cellulose derivative, or polyvinyl alcohol as an ink image receiving layer on a substrate. The ink image-receiving layer has poor solubility, and the surface is sticky, blocking occurs when the recording sheets are stacked, and there is a practical problem.

Further, Japanese Patent Publication No. 3-72460 discloses that
There has been proposed a method comprising a combination of an ink-permeable surface layer and an ink-absorbing underlayer, in which ink is absorbed by the underlayer and blocking resistance is improved by the surface layer. However, since the ink passes through the surface layer and is absorbed by the underlying layer, the ink has a deep feeling of penetrating into the recording sheet, so that the color density of the recorded portion is difficult to come out. There are also the problem of peeling and the problem of low water resistance of the underlayer.

Further, there has been proposed a method in which a porous layer is provided as an ink absorbing layer so as to absorb ink by a capillary phenomenon, as disclosed in JP-A-58-110287 and JP-A-5-210287.
JP-A-51470 proposes a recording sheet in which fine particles such as silica are aggregated and a porous layer having pores formed by gaps between the particles is provided on a base material layer. These inks have improved ink absorbency, but have a problem that the surface gloss is low due to light scattering of particles and the ink absorption capacity is not sufficient.

Japanese Patent Application Laid-Open No. 61-86251 proposes a recording sheet in which a porous plastic thin film layer is laminated on an ink absorbing layer, but the porous plastic thin film is formed of a hydrophobic plastic such as polyethylene or polypropylene. For this reason, in ink-jet recording in which water-based ink is mainly used, ink permeability is not sufficient, and holes are crushed or deformed because a porous plastic thin film is laminated by a thermocompression bonding method.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the ink absorption and blocking resistance, and to improve the surface gloss of the image receiving layer, the clarity of the recorded image, the water resistance, the weather resistance and the color reproducibility. An object of the present invention is to provide a recording resin composition for forming a possible image receiving layer and a recording sheet on which an image receiving layer is formed.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a cellulose derivative, a good solvent for the cellulose derivative, and an organic solvent soluble in a good solvent or poor solvent for the cellulose derivative. By using a recording resin composition containing an acid and optionally a poor solvent of a cellulose derivative in a specific ratio, it has been found that the surface gloss of an image receiving layer of a recording medium, the sharpness of a recorded image, and the like can be significantly improved. Thus, the present invention has been completed.

That is, the present invention relates to a recording resin composition for forming a recording layer, wherein (1) 1 to 30% by weight of a cellulose derivative (A), and (2) a good solvent (B) 70 of the cellulose derivative. And 99% by weight (the total of both is 100% by weight), and (3) an organic acid (C) soluble in a good solvent (B) or poor solvent (D) of a cellulose derivative. Provided is a recording resin composition containing 0.1 to 20 parts by weight and optionally 0 to 150 parts by weight of a poor solvent (D) of a cellulose derivative. The present invention also provides a recording resin composition wherein the cellulose derivative (A) of the invention is cellulose acetate, a recording resin composition wherein the ratio of the poor solvent (D) of the cellulose derivative is 50 to 150 parts by weight, and The good solvent (B) for the cellulose derivative is at least one selected from the group consisting of ketones, esters, ethers, cellosolves, cellosolve acetates, halogenated hydrocarbons and nitro compounds, and has a boiling point of 35 ° C. A recording resin composition having a temperature of up to 160 ° C. is provided.

In the above invention, the recording resin composition in which the melting point of the organic acid (C) is 60 ° C. or higher, and the poor solvent (D) for the cellulose derivative are selected from esters, alcohols, ketones and ethers. A recording resin composition having a boiling point of at least 100 ° C. and a good solvent for a cellulose derivative (B) is a C _1-5 dialkyl ketone, a C _1-4 alkyl ester acetate, a cyclic or a chain. At least one selected from the group consisting of C _4-6 ether, C _1-4 alkyl cellosolve, and C _1-4 alkyl cellosolve acetate, wherein the poor solvent (D) for the cellulose derivative is a formic acid C _5-8 alkyl ester Benzoic acid C _1-4
Alkyl ester, C _4-8 cycloalkanol, C _6-10
Provided is a recording resin composition which is at least one selected from dialkyl ketones and C _7-10 ethers. Further, the present invention provides a cellulose derivative having a difference (TD-TB) in boiling point between the good solvent (B) and the poor solvent (D) of 10 ° C <(T
D-TB) <200 ° C., the solubility of the organic acid (C) in water is 2 g / 20 ° C.
Provided is a recording resin composition of 100 ml or less, and a recording sheet formed by applying the recording resin composition on a substrate and forming an image receiving layer on a recording medium.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. Cellulose derivatives (A) used in the present invention include cellulose esters, for example, organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate, and sulfuric acid. Cellulose, inorganic acid esters such as cellulose phosphate, mixed acid esters such as cellulose nitrate acetate, cellulose ethers such as methyl cellulose, ethyl cellulose, isopropyl cellulose, butyl cellulose, benzyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, cyanoethyl cellulose, etc. Is mentioned. Of these, cellulose esters and, more preferably, cellulose acetate are preferably used. These may be used alone or as a mixture. Further, if necessary, another polymer may be added.

Examples of the good solvent (B) for cellulose derivatives include C _1-5 dialkyl ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone and methyl isobutyl ketone, ketones such as cyclohexanone, and ethyl formate. formic acid C _1-4 alkyl esters, methyl acetate, ethyl acetate, acetic acid C _1-4 alkyl ester such as butyl acetate, ethyl propionate, and ethyl lactate, 1,4-dioxane, tetrahydrofuran, tetrahydropyran, diethyl ether ,
Ethers such as cyclic or chain C _4-6 ethers such as diisopropyl ether and dimethoxyethane; C _1-4 such as methyl cellosolve, ethyl cellosolve and butyl cellosolve;
Cellosolves including alkyl cellosolve, cellosolve acetates (C _1-4 alkyl cellosolve acetate such as methyl cellosolve acetate, ethyl cellosolve acetate), aromatic hydrocarbons such as benzene, toluene, xylene, and halogens such as methylene chloride and ethylene chloride Hydrocarbons, formamide, acetamide, N-methylformamide, N-methylacetamide, N, N-dimethylformamide, amides such as N, N-dimethylacetamide, sulfoxides such as dimethylsulfoxide,
Acetonitrile, propionitrile, butyronitrile,
Examples thereof include nitriles such as benzonitrile, formic acid, acetic acid, propionic acid, etc., organic acid anhydrides (organic acids such as maleic anhydride, acetic anhydride, etc.), and mixtures thereof, etc. Good solvents, for example, lower alcohols (Methanol,
C _1-4 such as ethanol, isopropanol and butanol
C _1-4 alkyl groups such as alkyl alcohols, diacetone alcohols, etc., and cycloalkanols (cyclopentanol, cyclohexanol, methylcyclohexanol, dimethylcyclohexanol, etc., which may be substituted by C _1-4 alkyl groups;
_4-8 cycloalkanol) etc. may be a poor solvent depending on the type of resin. Good solvents are nitro compounds (nitromethane, nitroethane, nitropropane, etc.)
May be included. A solvent that is at least one selected from the group of these solvents and has a boiling point of 35 ° C to 160 ° C is preferably used.

More specifically, when cellulose acetate is used as the polymer, preferred good solvents include acetone, methyl ethyl ketone, ethyl acetate, dioxane, dimethoxyethane, methyl cellosolve, methyl cellosolve acetate, and mixtures thereof, especially acetone. Is preferably used.

The poor solvent means a solvent having no solubility in the cellulose derivative to be used or having a lower solubility than the good solvent to be used. If the boiling point is higher than that of the good solvent to be used in combination, The type is not particularly limited. Examples of the poor solvent (D) for the cellulose derivative include water, esters (C _5-8 alkyl esters such as amyl formate and isoamyl formate, amyl acetate, hexyl acetate, octyl acetate, 3-methoxybutyl acetate, and acetic acid). 3-
Ethoxybutyl, butyl propionate, propionate 3
_C2-4 aliphatic carboxylic acid _C6-10 alkyl ester which may have a _C1-4 alkoxyl group such as _{-methoxybutyl} ,
Benzoic acid C _1-4 alkyl esters such as methyl benzoate, ethyl benzoate and propyl benzoate, etc., alcohols (C _6-10 alcohols such as amyl alcohol, heterocyclic alcohols etc.), aliphatic polyhydric Examples thereof include alcohols (ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerin and the like), and mixtures thereof.

More specifically, when cellulose acetate is used as the polymer, preferred poor solvents include amyl formate and
Preference is given to cyclohexanol, methylcyclohexanol, ethyl benzoate or mixtures thereof, especially cyclohexanol. Further, a solvent having a boiling point of 100 to 300 ° C is more preferable.

Examples of the organic acid (C) include formic acid, acetic acid, propionic acid, lactic acid, citric acid, oxalic acid, benzoic acid, sulfamic acid, fumaric acid, maleic acid, phthalic acids (phthalic acid, isophthalic acid), Paratoluenesulfonic acid and the like can be mentioned. Of these, phthalic acids and their derivatives are particularly preferred. Among these, an organic acid having a melting point of 60 ° C. or higher is more preferable.

Also, as a combination of a good solvent and a poor solvent,
Means that the good solvent (B) is_1-5Dialkyl ketone, acetic acid C
_1-4Alkyl ester, cyclic or linear C_4-6ether,
C_1-4Alkyl cellosolve, and C_1-4Alkyl celloso
At least one selected from lube acetate,
The poor solvent for cellulose derivative (D) is formic acid C_5-8Archi
Ester, benzoic acid C_1-4Alkyl ester, C_4-8Shi
Chloralkanol, C _6-10Dialkyl ketone and C
_7-10A solvent that is at least one selected from ethers
Are also preferred.

The recording resin composition of the present invention can be mixed by a conventional method, for example, by dissolving a cellulose derivative and an organic acid in a good solvent, then adding a poor solvent and stirring.

In the recording resin composition, conventional additives such as an antifoaming agent, a coating improver, a thickener, a heat stabilizer, a lubricant, and an ultraviolet absorber as long as the properties of the present invention are not impaired. , A light stabilizer, an antistatic agent, a crosslinking agent, an anti-blocking agent, and the like. The method for applying the recording resin composition to the base sheet is not particularly limited, and roll coating, air knife coating, blade coating,
Known methods such as bar coating, comma coating, and gravure coating can be used.

The applied resin layer is dried to obtain a recording sheet having an image receiving layer formed on a recording medium. The drying method is not particularly limited, and when a dry phase inversion method is used, first, the good solvent evaporates to convert the cellulose derivative into micelles, and then the micelles contact each other due to the evaporation of the poor solvent to form a network structure. It is necessary to control the temperature, the vapor pressure, etc., so as to form.

[0022]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, parts or percentages of the mixing ratio are based on weight. The recording sheets obtained in the examples and comparative examples were evaluated for ink absorption, water resistance, image resolution, and blocking resistance as follows. [Ink absorbency]: Ink jet printer (Graphtec,
Using MasterJet-JC2008), a pigment-type aqueous ink (each color of cyan, yellow, and magenta) was solidly printed on the recording sheets obtained in Examples and Comparative Examples to form a recorded image. After printing, copy paper for PPC is placed on the print unit at regular intervals, and a load of 24.5 kPa (250 gf / c
After applying m ² ) for 10 seconds, the copy paper was peeled off, the degree of ink set-off was visually judged, and the time until the set-off was not recognized was measured. [Water resistance]: The recording sheet obtained in the example was printed in the same manner as in the ink absorption test, immersed in water at room temperature for 24 hours, and visually evaluated according to the following criteria. ：: No abnormality. Δ: Slight elution of image area. X: Most of the image part eluted. [Image resolution]: Using an ink jet printer (MasterJet-JC2008, manufactured by Graphtec), the recording sheets obtained in Examples and Comparative Examples were
After printing a yellow-based magenta line (width 100 μm), observe the dots by magnifying 50 times with a microscope,
Evaluation was made according to the following criteria. A: There is almost no bleeding around dots. ：: There is little bleeding around the dot, and the measured value is 120
exceeds μm. ×: Bleeding around the dots, and the boundary between adjacent yellow and magenta dots is unclear. [Blocking resistance]: Two or more recording sheets obtained in Examples and Comparative Examples were stacked, and 3.92 k
Apply a load of Pa (40 gf / cm ² ) at 40 ° C., 9
It was stored for 1 day under 0% RH humidity and evaluated according to the following criteria. A: Neither matting nor blocking. ：: There is matting but no blocking. ×: Blocking.

Example 1 A 100 μm thick polyethylene terephthalate film (manufactured by DuPont, Melinex 3)
On one side of 39), an 18% aqueous solution of polyvinyl alcohol (OKS7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied as a coating solution, and dried at 120 ° C. for 5 minutes to form a layer having a thickness of 15 μm. Further, the following resin composition-a for recording was applied thereon, and dried at 80 ° C. for 5 minutes to form a recording sheet having a 7 μm-thick porous image receiving layer in which pores having an average pore diameter of 1 μm exist at high density. I got Table 1 shows the evaluation results of the recording sheets.

(Recording Resin Composition-a) Cellulose acetate as cellulose derivative (degree of acetylation: 55, average degree of polymerization:
170) A recording resin obtained by adding 5 parts by weight of phthalic acid as an organic acid and 100 parts by weight of cyclohexanol as a poor solvent to 100 parts by weight of a 10% solution prepared using acetone as a good solvent for cellulose acetate. Composition-a was obtained.

Example 2 An 18% aqueous solution of polyvinyl alcohol (OKS7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied as a coating solution on one side of a 100 μm-thick polyethylene terephthalate film (Melinex 339, manufactured by DuPont). After drying for 5 minutes, a layer having a thickness of 15 μm was provided. Further thereon, the following recording resin composition-b
And dried at 80 ° C. for 5 minutes to have an average pore diameter of 1 μm.
A recording sheet having a porous image receiving layer having a thickness of 7 μm in which pores are present at a high density was obtained. Table 1 shows the evaluation results of the recording sheets.

(Resin composition for recording-b) Cellulose acetate as cellulose derivative (degree of acetylation: 51, average degree of polymerization:
250), for 100 parts by weight of a 13% solution prepared by using acetone as a good solvent for cellulose acetate, 2 parts by weight of terephthalic acid as an organic acid and 90 parts by weight of cyclohexanol as a poor solvent are added for recording. Resin composition-
b was obtained.

(Example 3) The resin composition for recording-a shown in Example 1 was applied to one surface of a synthetic paper (Yupo FPG110, manufactured by Oji Yuka Paper) having a thickness of 110 µm,
After drying for a minute, a recording sheet having a 7 μm-thick porous image receiving layer in which pores having an average pore diameter of 1 μm were present at high density was obtained.
Table 1 shows the evaluation results of the recording sheets.

Comparative Example 1 An 18% aqueous solution of polyvinyl alcohol (OKS7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied as a coating solution on one surface of a polyethylene terephthalate film (manufactured by DuPont, Melinex 339) having a thickness of 100 μm. After drying for 5 minutes, an image receiving layer having a thickness of 15 μm was provided. Table 1 shows the evaluation results of the recording sheets.

[0029]

[Table 1]

[0030]

According to the present invention, it is possible to produce a recording medium or a recording sheet having excellent ink absorption, blocking resistance, color reproducibility, recorded image or character water resistance, weather resistance, and surface gloss.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 FC06 2H086 BA01 BA15 BA31 BA36 BA41 4J002 AB021 AB031 EA036 EB106 EC016 EC037 ED026 EE036 EF038 EF078 EF098 EF118 EH036 EH127 EL066 EP016 ET006 EV206 EV238 GS00

Claims (10)

[Claims] 1. A recording resin composition for forming an ink recording layer, comprising: (1) a cellulose derivative (A)
30% by weight, (2) good solvent for cellulose derivative (B) 7
100 parts by weight of a resin composition comprising 0 to 99% by weight (the total of both is 100% by weight); and (3) an organic acid (C) soluble in a good solvent (B) or poor solvent (D) of the cellulose derivative. A) a recording resin composition comprising 0.1 to 20 parts by weight and optionally (4) a poor solvent (D) of a cellulose derivative in a ratio of 0 to 150 parts by weight. 2. The recording resin composition according to claim 1, wherein the cellulose derivative (A) is cellulose acetate. 3. The recording resin composition according to claim 1, wherein the ratio of the poor solvent (D) of the cellulose derivative is 50 to 150 parts by weight. 4. The good solvent (B) for the cellulose derivative is at least one selected from the group consisting of ketones, esters, ethers, cellosolves, cellosolve acetates, halogenated hydrocarbons and nitro compounds, The boiling point is 35 ° C to 160 ° C.
4. The recording resin composition according to any one of items 1 to 3. 5. The recording resin composition according to claim 1, wherein the melting point of the organic acid (C) is 60 ° C. or higher. 6. The poor solvent (D) of the cellulose derivative is at least one selected from esters, alcohols, ketones and ethers, and has a boiling point of 100 to 100.
The recording resin composition according to claim 1, wherein the temperature is 300 ° C. 5. 7. A method according to claim 1, wherein the good solvent (B) for the cellulose derivative is C
Cellulose at least one selected from _1-5 dialkyl ketones, C _1-4 alkyl acetate acetate, cyclic or linear C _4-6 ether, C _1-4 alkyl cellosolve, and C _1-4 alkyl cellosolve acetate; The poor solvent (D) of the derivative is C _5-8 alkyl formate, C _1-4 alkyl benzoate, C _4-8 cycloalkanol, C _4-8
4. The recording resin composition according to claim 1, wherein the resin composition is at least one selected from _6-10 dialkyl ketones and C _7-10 ethers. 8. The difference in boiling point (TD-TB) between the good solvent (B) and the poor solvent (D) of the cellulose derivative is 10 ° C. <(TD
The recording resin composition according to claim 1 or 7, wherein -TB) <200 ° C. 9. The organic acid (C) having a solubility in water of 20
The recording resin composition according to claim 1 or 2, wherein the composition is 2 g / 100 ml or less at a temperature of ° C. 10. A recording sheet comprising a substrate and the recording resin composition according to claim 1, and an image receiving layer formed on a recording medium.