JP2514194B2 - Inkjet recording sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a recording sheet for an inkjet printer.

[Conventional technology]

In general, ink jet recording is a system in which ink is ejected under pressure from pores having a diameter of several tens of microns and dots are recorded on a recording paper by the generated ink fine particles. Since it is necessary to ensure stable ink ejection from the pores, it is difficult to incorporate pigments, resins, etc. into the ink like ordinary printing inks, and it is generally composed of water-soluble dyes such as direct dyes and acid dyes. A low viscosity aqueous ink is used. For this reason, it was taken for granted that inkjet recording is inferior to general printing in recording quality such as recording density, gloss, light resistance, and water resistance.

However, with the expansion of the fields of use of ink jet recording systems and the widespread use of color printers, not only the performance at the time of recording, that is, resolution, density, and vividness of color tone, but also storage stability such as water resistance and light resistance after recording is required. Came to be.

Among them, as a measure for the resolution of recording, density, and vividness of color tone, Japanese Patent Application Laid-Open Nos. 55-51583, 56-148583, and 56-148585 disclose paints containing a silica-based pigment and a water-soluble polymer binder. It has been proposed to coat 10 g / m ² or more on a support.
-185690 particle size distribution (Rosin-Rammler
(Distribution) with a uniform number n of 1.10 or more and a coating layer containing silica and a water-soluble polymer binder having a specific surface area of 200 m ² / g or more according to the BET method to provide clearer ink color reproducibility. Proposed to be obtained.

Further, as a method for making an ink jet recorded image waterproof, there is disclosed in JP-A-56-84992 and JP-A-59-20696.
46889, JP-A-60-49990 and the like propose a method of printing an aqueous ink on a recording medium containing various cationic polymers on its surface.

Water resistance by this method is due to the formation of a water-insoluble complex due to the combination of the direct dye or acid dye in the ink and these cationic polymers.

However, when ink jet color recording is applied to recording papers using these cationic polymers, etc., a significant improvement in image water resistance is recognized as compared with recording papers without addition, but the following drawbacks Can be seen.

In color inkjet recording, inks of four basic colors of black, cyan, magenta, and yellow are generally used, and the other colors are expressed by subtractive color mixing of the basic inks. Most popular color ink jet printers are of the serial type, and when obtaining color mixture, the order of superposition of basic colors is reversed in forward and backward. When a cationic polymer is used as a waterproofing agent, in this color mixture, the so-called color misregistration, which is different depending on the order in which the inks are superposed, is significantly increased. As a result, for example, in the case where the entire surface of purple is recorded in the order of cyan and magenta in the forward pass, and the reverse pass is repeated to perform the recording in reverse, the obtained screen shows stripes due to color shift in the forward pass and the return pass. There was a defect that it was visually recognized as a pattern. In addition, there is also a drawback in that at the boundary of different hues such as black to red, the color bleeds from one side to the other or to each other, and the boundary line becomes unclear (referred to as bleeding). The inventors of the present invention, in JP-A-61-89082, apply or impregnate a paint containing a silicone emulsion or a water-soluble silicone compound for the purpose of improving color misregistration and image resolution due to the difference in the overlapping order of color mixture. An inkjet recording sheet was proposed. However, this method has a drawback that it tends to hinder the adhesion between the pigment and the binder due to its water repellency, which lowers the surface strength of the coated surface.

[Problems to be solved by the invention]

The present invention improves the color misregistration, that is, the stripes due to the difference in the superposition order of the basic colors in color recording, while maintaining the image density and the image water resistance and without lowering the surface strength of the coating layer. It is intended to provide an ink jet recording sheet for the purpose of improving the bleeding of ink into other colors at color boundaries.

[Means for solving problems]

The present invention has conducted extensive studies to solve the above-mentioned problems, and as a result, in an ink jet recording sheet for forming a recorded image using a water-based ink containing a water-soluble dye, the sheet is a cationic polymer and a cationic interface. The above-mentioned object was achieved by coating or impregnating a support with an activator.

 The present invention will be described in detail below.

The cationic polymer of the present invention is a polymer or copolymer containing a tertiary amine or / and a quaternary ammonium salt, and is polyallylamine, dicyandiamide formalin condensate, polyethyleneimine, polyethyleneimide quaternary ammonium salt compound, dimethyl. Examples thereof include a diallylammonium salt polymer, a (meth) acrylic acid alkylammonium salt polymer, a (meth) acrylamidoalkylammonium salt polymer, and ionene containing a quaternary ammonium salt.

Examples of the cationic surfactant of the present invention include primary to tertiary amine hydrochlorides and acetates such as alkylamines, ethanolamines and polyoxyethylene-added amines, quaternary ammonium salts thereof, ethylenediamine, diethyleneditriamine. Polyethylene polyamines, etc., etc.
Examples include amines such as N, N diethylenediamine, amine ethylethanolamine, pyridine, guanidine, and hydrazine. Among these, quaternary ammonium salts of alkylamines and oxyethylene-added amines can be mentioned as those having excellent effects including water resistance.

A general and preferred method for producing a recording sheet using these cationic polymer and cationic surfactant is a mixed slurry containing a water-soluble polymer binder, a pigment, a cationic polymer and, if necessary, various additives. In addition, a coating solution containing a cationic surfactant is applied to the surface of paper.

However, the method is not limited to this method, and any method of coexisting a cationic polymer and a cationic surfactant is possible depending on the quality required of the recording sheet.

For example, a layered structure in which a first layer comprising a binder and a cationic polymer is coated on a support, and then a cationic surfactant solution is coated as the second layer together with the binder or alone, or a cationic polymer. And a cationic surfactant together with the required additives are impregnated into the support. Examples of the method of impregnation include a method of adding these to a pulp slurry for papermaking, a method of permeating non-sized base paper with a size press, and a method of immersing a support in these solutions.

As the pigment, silica, synthetic silicate, talc, kaolin, clay, heavy or light calcium carbonate, other carbonates, acid clay, aluminum hydroxide, diatomaceous earth, titanium oxide, zinc oxide, barium sulfate, urea formalin resin Powders, ethylene resin fine powders, styrene resin fine powders, and the like can be used by mixing them.

Water-soluble polymer binders include PVA, oxidized starch, etherified starch, other starch derivatives, gelatin, casein, carboxymethyl cellulose, hydroxyethyl cellulose, other cellulose derivatives,
Polyvinylpyrrolidone or the like is used alone or in combination. Further, as the adhesive, styrene / butadiene copolymer, methyl methacrylate / butadiene copolymer, acrylic ester copolymer, polyvinyl acetate, ethylene /
Latex and emulsion such as vinyl acetate copolymer can also be used.

Among the above, as the pigment, a silica-based one is preferable, and among them, amorphous silica by a wet method containing silicon dioxide as a main component is preferable, and as the water-soluble polymer binder,
A combination of PVA (polyvinyl alcohol) is particularly preferable in terms of image density and sharpness.

In addition to these, pigment dispersants, surfactants, defoamers, colorants, antioxidants, ultraviolet absorbers, release agents, viscosity modifiers, binder cross-linking waterproofing agents, etc. are added as necessary. It can be used together with a cationic polymer or a cationic surfactant.

Among these additives, nonionic surfactants and amphoteric surfactants are preferable because they further improve the sharpness of images and bleeding.

Examples of nonionic surfactants having excellent effects include polyoxyethylene derivatives such as polyoxyethylene-oxypropylene copolymer, polyoxyethylene lauryl ether, polyoxyethylene monolaurate, polyoxyethylene nonylphenyl ether, and polyoxyethylene nonylphenyl ether. Oxyethylene oleyl ether, polyoxyethylene monooleate, polyoxyethylene higher alcohol ether, polyoxyethylene sorbitan trioleate, etc.,
Further examples include sorbitan monolaurate, polyethylene glycol distearate, glycerol monostearate, fluorine-based nonionic surfactants, and silicon-based surfactants. Examples of both surfactants include dimethylalkyl (coconut) betaine, dimethylalkyllaurylbetaine, dimethylalkylstearylbetaine, 2-
Examples thereof include alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium bentine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and the like.

The coating amount or impregnation amount of the cationic polymer of the present invention is
Solid content of about 0.05 to 2.5 g / m ² , preferably 0.1 to 1.5 g
A sufficient image / water resistance effect is exhibited at / m ² . The coating amount or impregnation amount of thione surfactant is 0.01 to 2.5 g / m ² as solid content.
The object of the present invention can be sufficiently achieved at a degree, preferably 0.05 to 1.5 g / m ² . Further, the coating amount or impregnation amount of the nonionic surfactant or amphoteric surfactant which may be added is in the range of 0.01 to 2.5 g / m ² as solid content. As a method for applying these paints, the conventional method can be used as it is. That is, size press, gate roll coater,
An air knife coater, blade coater, spray, etc. can be used. When the coating amount of the cationic polymer and the cationic surfactant is single or the entire mixture is used, off-machine coating can be applied, and on the other hand, on-machine coating can be applied. Is.

[Work]

The combination of cationic polymer and cationic surfactant
The reason for improving color misregistration, recording stripes, and bleeding is not clear, but it is estimated as follows.

When a recording paper containing a cationic polymer in the recording layer is mixed and printed by a reciprocating printer, the dye in the ink particles ejected first is strongly adsorbed and captured by the cationic polymer near the surface layer, and the spread of dots is also small. . 2 on this
When the ink particles of the second color arrive, the adsorption seat of the cationic polymer on the surface layer is mostly occupied by the dye in the previous ink, and the adsorption seat of the dye in the second ink is small and The reason is that the inks of the two inks are not sufficiently mixed because the dye of the second color is strongly captured, and the second color of the ink appears strongly as the upper color, and the ink of the second color exceeds the spread of the preceding ink. It is considered that widening causes large color misregistration and recording stripes. Further, it is considered that the presence of the cationic polymer slows the permeation of the ink into the inside of the support, so that the lateral movement is increased and the bleeding easily occurs.

On the other hand, if a cationic polymer and a cationic surfactant are used in combination as in the present invention, most of the preceding ink dyes preferentially have a cationic surface because the cationic surfactant is present in the surface layer more than the cationic polymer. Reacts with activators. The complex formed by this reaction has a significantly weaker bond than the complex with the cationic polymer, and the strong solubilizing action of the complex by the cationic surfactant micelles present at the same time facilitates the mixing of the second color ink and the preceding ink. It is estimated that it will take place and become established. As a result, a color image with no color shift or recording stripes can be obtained. In addition, seepage is
It is believed that the presence of the cationic surfactant promotes and improves the penetration of the ink into the support. The action of these cationic surfactants is remarkable in the presence of the cationic polymer, but the reason for this is unknown. Further, regarding the image water resistance, even if a cationic surfactant is somewhat effective for simple wetting, under severe conditions such as dipping in water, the surfactant will also elute as a dye and the ink dye Water resistance will be secured by re-fixing of the polymer onto the cationic polymer.

〔Example〕

An example will be described below. Incidentally, parts and% in the examples
Represents parts by weight and% by weight unless otherwise specified.

The quality test method of the obtained recording paper is as follows.

(1) Recording density: Black, cyan ,, using an inkjet color printer (Sharp Corp .; IO-700)
Performs full recording of four colors, magenta and yellow, and uses black SPI for black portion, cyan red for cyan portion, magenta green for magenta portion, and yellow blue for yellow portion. Densitometer (made by Macbeth;
It is shown as the total value of the reflection optical density measured by RD915).

(2) Image water resistance: 24
After immersing in water for a period of time, the recorded matter was taken out and dried, and the recorded density was measured again and expressed by the recording density change rate (%).

(3) Color shift and recording stripes: purple (cyan-magenta), red (magenta-yellow), and green (yellow-cyan)
The measurement was carried out for the three mixed colors.

After recording the above three colors on the entire surface by reciprocal printing, the color densities of the overlapping colors are measured for the forward and backward paths by a Sakura Microdensitometer PDM5 (manufactured by Konishi Rokusha Kogyo Co., Ltd.). For example, in the case of green cyan, measures the recording density of the two colors of yellow, adding a density difference delta ₂ forward and return of the forward and return density difference delta ₁ and yellow component of the cyan component Δ _{1 +} Δ ₂ = d was defined as the degree of green color shift. The color shifts of other mixed colors were similarly obtained.
The evaluation of the color misregistration was performed by summing the size d of the color misregistration of the three mixed colors.

 The recording stripes are represented by the size of color shift.

(4) Bleed-in: Black / red, cyan / red, magenta / green, and yellow / purple, which are particularly noticeable at the boundary line between monochromatic and mixed colors having different amounts of adhered ink and which are particularly noticeable
For each combination, a pattern was created such that they were adjacent to each other, and the bleeding width on the boundary line was visually measured.
No bleeding ... A, 0.3 mm or less ... B, 0.3 mm to 1 mm ... C, 1 mm
Above ... It was set as D. A and B are practical ranges.

(5) Surface strength of recording surface: Using commercially available cellophane tape (Nichiban 18 mm width),
After sticking on the recording surface of each sample with a constant pressure of about 7 cm, when the cellophane tape was peeled from one end after 1 minute,
Check the peeling state of the coating layer to the side of the cellophane tape.

A: Excellent: Very little peeling of the coating layer.

B: Good: Some peeling of the coating layer is observed.

C: Impossible: The coating layer peeled off frequently.

[Example 1] 1000 parts of a 17% slurry of synthetic silica (manufactured by Nippon Silica Industry Co., Ltd .; Nipseal E220A) as a pigment and a 10% aqueous solution of completely saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; PVA117) as a binder 300 Parts and mixed with water to prepare a paint having a solid content of 15%. Further, for 1000 parts of this paint, polydimethyldiallylammonium chloride (manufactured by Nitto Boseki Co., Ltd .; PASH) was used as a cationic polymer.
27 parts of a 28% aqueous solution (-10 L) was added to prepare a solution (a). In addition to this solution (a), as solution (b), dodecyltrimethylammonium chloride (NOF CORPORATION; cation B)
A coating solution was prepared by adding 3 parts of the 50% solution B). The support is 80 parts of LBKP with a freeness of 350 ml and NBKP with a freeness of 400 ml.
To 20 parts of pigment pulp, 20 parts of light calcium carbonate powder (manufactured by Shiraishi Kogyo Co., Ltd., PC) was added, and a neutral size paper weighed 60 g / m ² made with a Fourdrinier machine was used. Each of the above-mentioned mixed paints was applied onto the support with a wire bar so that the applied amount was about 10 g / m ² . Further, an inkjet recording sheet was obtained by making a test calendar (manufactured by Yuri Roll Co., Ltd.) so that the Bekk smoothness of these papers was 90 to 140 seconds.

[Comparative Examples 1 to 4] In Example 1, the cationic polymer in the liquid (a):
A recording sheet was obtained in the same manner except that the polydimethyldiallylammonium salt was not added (Comparative Example 1). Further, a recording sheet was obtained in the same manner as in Example 1 except that the liquid (b) was not added (Comparative Example 2). Further, the polydimethyldiallylammonium salt of the liquid (a) of Example 1 was replaced with polyallylamine hydrochloride (manufactured by Nitto Boseki Co., Ltd .; PAA-HCl).
H) A recording sheet was obtained in the same manner except that 25 parts of a 30% aqueous solution was added and the solution (b) was not added (Comparative Example 3). Furthermore, the same recording was carried out except that 1.5 parts of polyoxyethylene tridecyl ether (Non-T208.5) as a 100% liquid was added in place of the cationic surfactant in the liquid (b) of Example 1. A sheet for use was obtained (Comparative Example 4).

[Example 2] Example 1 except that 1.5 parts of polyoxyethylene nonylphenyl ether (Miyoshi Yushi Co., Ltd .; Pelletex (1223)) as a 100% liquid was added to the liquid (a) of Example 1 as a nonionic surfactant. A recording sheet was obtained in the same manner as in.

Example 3 A recording sheet was obtained in the same manner as in Example 1 except that 25 parts of a 30% aqueous solution of polyallylamine hydrochloride (same as above) was added in place of the polydimethyldiallylammonium salt of the liquid (a).

Example 4 Instead of the dodecyltrimethylammonium chloride of the liquid (b) of Example 1, a polyoxyethylene alkyl quaternary compound was used.
A recording sheet was obtained in the same manner as in Example 1 except that 75% of a high-grade ammonium salt (manufactured by Lion Akzo Co., Ltd., Esocard 0/12) was added.

[Example 5] In Example 1, dimethylalkyllauryl betaine (Kao Soap Co., Ltd.) was added to the liquid (a) as an amphoteric surfactant.
A recording sheet was obtained in the same manner except that 1.5 parts of a 100% solution of Amchthol 20BS) was added.

[Example 6] As a cationic polymer, 20% of a β-methacryloyloxyethyltrimethylammonium chloride polymer was used.
50 parts of an aqueous solution and 6 parts of a 50% solution of dodecyltrimethylammonium chloride (cation BB) as the cationic surfactant used in Example 1 are 10% aqueous solutions of polyvinyl alcohol (Kuraray Co., Ltd .; PVA117) which is an aqueous binder solution. The neutral base paper used in Example 1 was coated and impregnated with 300 parts of the coating liquid so as to be 15 g / m ^{2 on} both sides with a size press, and calendered so that the Bekk smoothness was about 60 seconds. An inkjet recording sheet was obtained.

Comparative Example 5 A recording sheet was obtained in the same manner as in Example 6 except that the cationic surfactant was not added.

[Example 7] A coating solution prepared by thoroughly mixing 400 g of a 5% aqueous solution of a copolymer of β-methacryloyloxymethyltrimethylammonium chloride and styrene as a cationic polymer with 800 parts of 10 aqueous solutions of oxidized starch was prepared. 10g / m ² on top
Applied and dried. Then, 0.8 g / m ² of lauryltrimethylammonium chloride (Kotamin 24P manufactured by Kao Soap Co., Ltd.) as a cationic surfactant was coated on the coating layer in a laminated manner and dried to obtain a recording sheet.

Comparative Example 6 A recording sheet was obtained in the same manner as in Example 7 except that the cationic surfactant was not laminated and applied.

The recording sheets prepared in Examples 1 to 7 and Comparative Examples 1 to 6 were tested by the method described above, and the results are shown in Table 1 for color misalignment (streaking), bleeding and surface strength. Table 2 shows the color density and water resistance.

[Advantages of the Invention] As described above, an ink jet recording sheet in which a support is coated or impregnated with a cationic polymer and a cationic surfactant uses a cationic polymer while maintaining excellent color density and water resistance. As a result, it was possible to remarkably reduce the color misregistration due to the difference in the stacking order of inks, the resulting stripe pattern, and the color bleeding that occurs at the boundary of different colors. It is possible to obtain an inkjet recorded image having excellent properties.

As a result, excellent recording can be obtained with popular color inkjet printers, contributing to the popularization of inkjet methods as an even lower noise recording method, and it is used in high-definition pictorial color printers and is comparable to photographs and printing. It has an effect that a high quality recorded image can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-55-150396 (JP, A) JP-A-56-99693 (JP, A) JP-A-58-147469 (JP, A) JP-A 58- 177390 (JP, A) JP 59-43065 (JP, A) JP 59-52689 (JP, A) JP 60-11389 (JP, A) JP 61-74880 (JP, A) JP-A-61-134291 (JP, A) JP-A-61-252189 (JP, A) JP-A-61-72581 (JP, A)

Claims (3)

(57) [Claims] 1. An inkjet recording sheet for forming a recorded image using a water-based ink containing a water-soluble dye, the sheet comprising a support coated with or impregnated with a cationic polymer and a cationic surfactant. Characteristic inkjet recording sheet. 2. The cationic polymer is a tertiary amine and / or
Alternatively, the in jet recording sheet according to claim 1, which is a polymer containing a quaternary ammonium salt. 3. The cationic surfactant is a quaternary ammonium salt of alkylamine or oxyethylene-added amine, respectively.
Ink jet recording sheet according to the item.