JPH032072B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an inkjet recording paper in which recorded images are completely waterproof and have excellent light resistance. In general, inkjet recording is a method in which ink is ejected under pressure from pores several tens of microns in diameter, and the generated ink particles record dots on recording paper several millimeters or tens of millimeters apart, so it has low viscosity and high surface tension. Water-based inks are commonly used. In order to ensure that ink is ejected from the pores, it is difficult to incorporate pigments, resins, etc. as in normal printing inks. For this reason, it is natural that inkjet recording is inferior in recording quality such as recording density, gloss, light resistance, and water resistance compared to general printing. However, as the field of use of the inkjet recording method expands, customers' quality requirements for inkjet recordings also become stricter.For example, in addition to recording resolution, density, and vividness of color tone, recording light resistance and water resistance are also required. There is a growing tendency to Naturally, when inkjet-recorded printed matter is displayed outdoors, simply storing it in a high-humidity environment can cause the recording to bleed and fade, and this tendency is especially common with color inkjet recordings. . Inkjet inks generally consist of water-soluble dyes classified as direct dyes, acid dyes, and basic dyes, water, dye solubilizers, wetting agents, etc.
Tones other than black are toned by mixing one or more of the three components yellow, magenta, and cyan.
A method of directly adding a water-proofing agent to the ink in order to make the recorded matter water-resistant is also considered, but this method has difficulties from the viewpoint of the above-mentioned ink composition and prevention of ink clogging. In Japanese Patent Application No. 57-130270, the present inventors proposed the use of a dimethyldiallylammonium chloride polymer to make recorded images water-resistant, and coated or impregnated a support with this dimethyldiallylammonium chloride polymer. It was shown that this method has a special effect not only on black recorded images but also on color recorded images in terms of water resistance. However, the recording paper according to this proposal was still insufficient in terms of water resistance of recorded images, leaving room for improvement. The inventors of the present invention have conducted further studies to solve this drawback, and have found that the above drawback can be improved by using polyethyleneimine in combination. In other words, inkjet recording paper obtained by coating or impregnating a support with dimethyldiallylammonium chloride polymer and polyethyleneimine has extremely excellent quality not only in terms of water resistance but also light resistance of recorded images. It was approved to show. The present invention will be explained in detail below. The dimethyldiallylammonium chloride polymer used in the present invention is a polymer having a monomer represented by the following structural formula as a constitutional unit. This dimethyldiallylammonium chloride polymer is a hygroscopic white powder that is used as a conductive agent.Its characteristic characteristic is that it dissolves well in water and its aqueous solution is extremely stable in both acidic and alkaline conditions. be. Regarding the average molecular weight, various types can be obtained depending on the manufacturing conditions, but those with an average molecular weight of about 50,000 to 520,000 are suitable for use, and those with a particularly large average molecular weight are excellent in water resistance and coatability. On the other hand, polyethyleneimine is a strongly thionic water-soluble liquid, and in JP-A-56-84992,
This is an example of a polycationic polymer electrolyte that has been proposed for use in making inkjet recorded images water resistant, but the water resistant effect of this polyethyleneimine is not great for color recorded images, except for black images. I can't expect too much. However, when polyethyleneimine is used in combination with the dimethyldiallylammonium chloride polymer, a very remarkable effect is seen not only in improving water resistance but also in improving light resistance. In the present invention, these combinations can be used by spraying them in an aqueous solution onto the surface of known inkjet recording paper, or by applying or impregnating the surface with a size press, roll coater, etc. during the papermaking process. Alternatively, it can be mixed into the paint of a known coat type inkjet recording paper, and
The coating may be applied using a coating machine such as an air knife or a roll coater. Therefore, the present invention is applicable to all types of inkjet recording paper, whether plain or coated, and can be applied to recording paper containing various fillers such as talc, kaolin, calcium carbonate, urea-formalin resin fine powder, etc. White pigments such as fine silica, acid clay, clay, talc, calcium carbonate, diatomaceous earth, titanium oxide, barium sulfate, etc. are mixed with water-soluble polymer binders such as oxidized starch, gelatin, casein, polyvinyl alcohol, cellulose derivatives, and polyvinylpyrrolidone. By using the inkjet recording paper coated with the inkjet inkjet recording paper, it is possible to obtain an inkjet recording paper which has extremely high color image water resistance and also has excellent image light resistance. The mixing ratio of the dimethyldiallylammonium chloride polymer and polyethyleneimine is set at a solid content ratio of 95 to 50 to 5 to 50, since too little of the former results in insufficient light resistance. Also, the amount of coating or impregnation is 0.1 to 2.5g/m ²
The image exhibits sufficient water resistance and light resistance at a certain level. The present invention will be described below with reference to Examples. Example In accordance with the known treatment method for coated type inkjet recording paper, 81 parts by weight (solid content) of a slurry of white carbon (Tokuyama Soda Co., Ltd., Tokusil U) was added as a pigment, and fully saponified polyvinyl alcohol (Kuraray) was added as a binder. 15 parts by weight (solid content) of an aqueous solution of PVA117, manufactured by Nittobo Co., Ltd., as well as dimethyldiallylammonium chloride polymer (PAS-H-10-L, manufactured by Nittobo Co., Ltd.) and polyethyleneimine (manufactured by Verdeisch Dye Chemicals Co., Ltd.) in various blending ratios. A series of paints with a solid content concentration of 15% were prepared by adding 4 parts by weight (solid content) of a mixture with Polymin P). These paints were applied on commercially available high-quality paper with a weight of 60 g/m ² and a Steckigt size of 20 seconds, using a wire bar to apply an amount of 8 to 12.
g/m ² and passed through a test calendar (manufactured by Yuri Roll Co., Ltd.) once at a linear pressure of 24 kg to obtain inkjet recording sheets No. 1 to No. 6. The light resistance test results of these recording papers are shown in Table 1 and FIG.

【table】

[Table] Total reflection density before irradiation From Table 1 and Figure 1, it can be seen that adding the other to either dimethyldiallylammonium chloride polymer or polyethyleneimine has the effect of reducing discoloration compared to when they are used alone. . still,
Regarding water resistance, all recorded materials are 24
Almost no color fastness was observed even after time immersion.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the fading rate in Table 1 in relation to the blending ratio.

Claims (1)

[Claims] 1. A dimethyl diallylammonium chloride polymer having a monomer represented by the following structural formula as a constituent unit and polyethyleneimine in a solid proportion of 95 to
An inkjet recording paper formed by coating or impregnating a support in a ratio of 50:5 to 50.