JP2002019271A - Ink receiving layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink receiving layer having an optimum printing quality and light resistance and excellent moisture resistance when a base of a printed product by an ink jet type is a material having flexibility. SOLUTION: The ink receiving layer comprises a composition containing at least (A) a polymer of a water soluble crosslinkable substance having a radical polymerizable water soluble monomer and two or more radical polymerizable groups in a molecule of a special structure, (B) a water soluble crosslinkable substance having two or more radical polymerizable groups in a molecule and a water soluble UV curing polymer, and (C) a photopolymerization initiator in such a manner that a photopolymerizable site is cured by emitting a light after printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-receiving layer having excellent print quality, light resistance and moisture resistance when a substrate of a printed material produced by an ink-jet method is a flexible material.

[0002]

2. Description of the Related Art Ink jet recording is a recording method capable of high-speed printing with low noise, and is a recording method that has been rapidly spreading recently. In such ink jet recording, recording is performed by discharging a recording liquid as small droplets by a method such as heating or pressurization and attaching the recording liquid to a recording material such as paper.

[0003] Dyes have been used as coloring materials for recording liquids. However, there are many cases where printed matter is exposed to the outdoors with diversification of recorded matter. Therefore, it is more advantageous to use a pigment than a dye in terms of water resistance and weather resistance of the ink. From the viewpoint of environment, it is more advantageous to use an aqueous liquid medium than a non-aqueous liquid medium.

[0004] Therefore, an aqueous pigment-based ink in which a pigment is used as a coloring material of a recording liquid and the pigment is dispersed in an aqueous liquid medium has been actively developed, and printing on various types of recorded materials has been spreading.

[0005] In the case where the base material to be printed does not absorb the aqueous ink, or when bleeding or the like occurs to cause a problem in print quality even if the water base ink is absorbed, the ink receiving agent which absorbs and fixes the ink on the surface of the printing material. A layer is provided.

[0006]

However, many recorded materials are inflexible, such as posters, signboards, and paper, and the conventional ink-receiving layer itself has flexibility. At present, printing on flexible base materials such as urethane rubber has not been put to practical use.

Accordingly, an object of the present invention is to provide an ink receiving layer which can be used for a flexible substrate, has high printing quality, and is excellent in light resistance and moisture resistance.

[0008]

The ink-receiving layer of the present invention contains at least the following composition, and is characterized in that a photopolymerizable portion is cured by light irradiation after printing. (A) Polymer of a water-soluble radically polymerizable water-soluble monomer and a water-soluble cross-linkable substance having two or more radically polymerizable groups in the molecule (B) Water-soluble cross-linkage having two or more radically polymerizable groups in the molecule Substance and water-soluble UV curable polymer (C) Photopolymerization initiator

The radically polymerizable water-soluble monomer of the composition (A) of the ink receiving layer of the present invention is characterized in that it is N, N-dimethylacrylamide.

The composition (A) of the ink receiving layer of the present invention,
The water-soluble crosslinkable substance having two or more radically polymerizable groups in one or both molecules of (B) has a polyethylene glycol group which may have an aromatic ring in the molecule, and the polyethylene The total number of ethylene oxide units in the glycol group is 20 to 30.

In one or both of the compositions (A) and (B) of the ink-receiving layer of the present invention,
The water-soluble crosslinkable substance having at least two radical polymerizable groups is urethane acrylate.

The composition (A) of the ink receiving layer of the present invention and the water-soluble UV-curable polymer (B) of the present invention each have a film forming ability alone.

[0013] Further, the printing method on a print using the ink receiving layer of the present invention is an ink jet method, and the ink used is an aqueous pigment comprising at least a dispersant, an aqueous liquid medium, a humectant, a pigment, and water. It is a system ink.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The ink receiving layer of the present invention may be provided on one side of a substrate and, if necessary, on both sides.

In the practice of the present invention, the base material is a plastic material having no flexibility, for example, a polyester resin, a polyolefin resin, an acrylic resin, or a glass material, a metal material, Alternatively, those having their surfaces painted can be used. Further, a flexible base material such as urethane rubber, natural or synthetic leather, soft vinyl, or a product obtained by applying a coating thereto can be used.

In the practice of the present invention, the base material is subjected to a hydrophilic treatment such as wet cleaning, coupling agent treatment, etching treatment, corona treatment, UV ozone treatment, etc. for the purpose of improving the adhesion to the receiving layer. Can be applied as needed.

The method for applying the ink-receiving layer of the present invention is not particularly limited, and ordinary methods such as roll coating, bar coating, spray coating and screen coating can be used.

[0018] If necessary, an ultraviolet absorber, an antioxidant, an antifoaming agent and the like may be added to the ink receiving layer as other additives.

The thickness of the ink receiving layer is not particularly limited, and can be changed in a wide range according to the amount of ink to be received. Usually, it is preferably in the range of several μm to 50 μm, and more preferably in the range of 5 to 30 μm.

The ink receiving layer of the present invention may additionally have other conventional layers such as an overcoat layer depending on the environment in which it is used. It is particularly useful when water resistance and abrasion resistance are required, such as wristwatch bands and sports bags.

In the practice of the present invention, a polymer of a radically polymerizable water-soluble monomer of the composition (A) of the ink receiving layer and a water-soluble crosslinkable substance having two or more radically polymerizable groups in a molecule is formed. The process can basically be carried out using a conventional polymerization method. For example, the polymerization can be carried out by reacting in the presence of a polymerization initiator at an elevated temperature of 50-70 ° C under a nitrogen atmosphere.

The polymerization initiator used here is preferably a water-soluble polymerization initiator. As a suitable polymerization initiator, for example, 2,2′-azobis (2-amidinopropane) dihydrochloride, 4,4′-azobis ′ (4,4-cyanovaleric acid), 2,2′-azobis [2 -(2-Imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane]
Disulfate dihydrate, 2,2′-azobisisobutyramide dihydrate, persulfate and the like can be mentioned. Furthermore,
If necessary, a polymerization accelerator and other additives may be added.

In the practice of the present invention, the coating liquid for the ink receiving layer applied to the substrate is basically a mixture of the solution containing the composition (A), the solution containing the composition (B) and (C), What is diluted with water or a water-soluble organic solvent depending on the coating method is used. Examples of the water-soluble organic solvent include, but are not limited to, alcohols such as methanol, ethanol, isopropyl alcohol, and 1,3-propanediol, and glycols such as ethylene glycol and propylene glycol.

In the practice of the present invention, the ink-receiving layer composition (A) and the water-soluble UV-curable polymer (B) alone have a film-forming ability, so that the ink-receiving layer before printing can be formed with a finger. It is not sticky when touched, making it easy to handle. .

In the practice of the present invention, the desired pattern is printed on the flexible ink receiving layer by an ink jet method using an aqueous pigment-based ink, and the printed matter is dried for the purpose of removing moisture and a humectant in the ink. Thereafter, the composition (B) in the ink receiving layer is cured by irradiating the composition with an ultraviolet ray using an ultraviolet irradiation apparatus. The curing conditions depend on the absorption wavelength of the photopolymerization initiator used, but a general ultraviolet curing light source (wavelength 300 to 4).
50 nm). By curing the composition (B) uniformly dispersed in the ink receiving layer, the printed ink is taken into the polymer and fixed. Further, the ink receiving layer itself becomes a tough and flexible film, and the moisture resistance is dramatically improved.

An embodiment of the present invention will be described below. The present invention is not limited by the following examples.

(Example 1) 80 parts by weight of pure water was charged into a reaction vessel and purged with nitrogen. Then, 10 parts by weight of N, N-
Dimethylacrylamide, 0.1 part by weight of N, N, N ', N'-tetramethylenediamine as a polymerization accelerator and 0.01 part by weight of ammonium persulfate as a polymerization initiator are added, and the mixture is stirred at 70 ° C. for 45 minutes. Was. Then, water-soluble urethane acrylate (trade name "UA-7000")
1.0 parts by weight and 0.01 parts by weight of ammonium persulfate were added and stirred at 70 ° C. for 1 hour to obtain an aqueous solution of the polymer (A). After that, heating was stopped and the polymer (A) dropped to room temperature.
2.5 parts by weight of a water-soluble UV-curable polymer as a solid content in an aqueous solution (trade name “NK Polymer B-1516S-1”)
1 ") and 1.0 parts by weight of UA-7000 and 0.1 part by weight.
15 parts by weight of a photopolymerizable initiator (trade name: Irgacure 1
173 ") was added to obtain a resin solution of the ink receiving layer having the following composition.

Composition (A): Polymer of N, N-dimethylacrylamide and UA-7000 Composition (B): NK Polymer B-1516S-11
And UA-7000 Composition (C): Irgacure 1173

(Example 2) In place of the water-soluble urethane acrylate used in the composition (A) and the composition (B) of Example 1, 1.5 times by weight of the diacrylate compound represented by the formula (1) was used. A resin solution for the ink receiving layer was obtained in the same manner as in Example 1 except for using the same.

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Example 3 In place of the water-soluble urethane acrylate used in the composition (A) and the composition (B) in Example 1, the same amount (by weight) of the diacrylate compound represented by Chemical Formula 2 was used. A resin solution for the ink receiving layer was obtained in the same manner as in Example 1 except for using the same.

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Example 4 Example 1 was repeated except that the water-soluble urethane acrylate used in the composition (B) of Example 1 was replaced with a 1.7 weight-fold diacrylate compound represented by Chemical Formula 1. A resin solution for the ink receiving layer was obtained in the same manner as in the above.

(Comparative Example 1) In place of the water-soluble urethane acrylate used in the composition (A) and the composition (B) of Example 1, 0.64 weight times of the diacrylate compound represented by the formula (3) was used. A resin solution for the ink receiving layer was obtained in the same manner as in Example 1 except for using the same.

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Comparative Example 2 The composition (A) and the composition (C) of Example 1 were used as a resin solution for an ink receiving layer.

Comparative Example 3 The composition (B) and the composition (C) of Example 1 were used as a resin solution for an ink receiving layer.

Example 5 Examples 1-4 and Comparative Example 1
To 1.5 cm in length, in which the resin solution prepared in each of Examples 1 to 3 was previously subjected to UV ozone treatment using a bar coater.
It was applied to a urethane resin base material having a width of 6.0 cm and a thickness of 2 mm so as to have a dry film thickness of 20 μm, and dried at 60 ° C. for 3 hours.

A pattern was printed in full color by an ink jet printer in which an aqueous pigment-based ink was mounted on the obtained base material coated with the ink receiving layer.

After printing, drying was conducted at 60 ° C. for 3 hours, and a test was conducted in accordance with the following procedure using a sample cured with an ultraviolet ray of 3000 mJ / cm 2 using an ultraviolet ray curing lamp.

In the meantime, those which failed in the initial test were not subjected to the subsequent test, and were evaluated as "-(not tested)".

(1) Print Quality The print quality was observed with a magnifying glass of 24 times, and the print quality was evaluated as “「 (pass) ”, and the print with bleeding or color mixture was evaluated as“ x (fail) ”. "

(2) Light fastness test Printed samples were prepared using a sunshine weather meter (light source:
Light irradiation was performed for 100 hours using a carbon arc lamp. If there is no fading in the design after the test, "○ (pass)"
Those which showed fading were evaluated as "x (fail)".

(3) Moisture Resistance Test The printed sample was placed horizontally and vertically on an environmental tester (constant humidity chamber) and left at 40 ° C./90% RH (relative humidity) for 100 hours. A symbol having no change in the design after standing was rated as “○ (pass)”, and a symbol with a change in picture flow or the like was rated “x (fail)”.

(4) Bending Test The repeated bending test of the printed sample was repeated 10,000 times by the method shown in FIG. After the test, those having no change in the pattern and the ink-receiving layer in the non-printed part were evaluated as “○ (pass)”, and those having cracks or peeling were evaluated as “x (fail)”.

Table 1 summarizes the results of each of the tests (1) to (4) described above.

[0044]

[Table 1]

[0045]

As described above, the results of Examples and Comparative Examples show that the ink receiving layer of the present invention has high print quality, light resistance and moisture resistance, and is particularly useful as an ink receiving layer of a flexible substrate. Further, the ink receiving layer of the present invention can be used for printing on posters, signboards and the like, similarly to the ordinary ink receiving layer.

Further, since the ink receiving layer of the present invention has flexibility, it can be used for printing on a flexible base material such as a watch band and a mobile phone strap. When used for these applications, further resistance to water and abrasion is required, but by providing an overcoat layer on the ink receiving layer, those properties can be sufficiently satisfied.

[Brief description of the drawings]

FIG. 1 shows a form of a bending test in Example 5 of the present invention.

Claims (6)

[Claims] At least the following (A), (B) and (C)
An ink receiving layer comprising the composition, wherein the photopolymerizable site is cured by light irradiation after printing. (A) Polymer of a water-soluble radically polymerizable water-soluble monomer and a water-soluble cross-linkable substance having two or more radically polymerizable groups in the molecule (B) Water-soluble cross-linking having two or more radically polymerizable groups in the molecule Substance and water-soluble UV curable polymer (C) Photopolymerization initiator 2. The ink receiving layer according to claim 1, wherein the radically polymerizable water-soluble monomer (A) is N, N-dimethylacrylamide. 3. The water-soluble crosslinkable substance having two or more radically polymerizable groups in one or both of the above (A) and (B) has an aromatic ring in the molecule. And the total of the ethylene oxide units of the polyethylene glycol group is 20 to 3
2. The ink receiving layer according to claim 1, wherein the value is 0. 4. The water-soluble crosslinkable substance having two or more radically polymerizable groups in one or both of the above (A) and (B) is a urethane acrylate. The ink receiving layer according to claim 1. 5. The polymer according to claim 1, wherein the polymer (A) and the water-soluble UV-curable polymer (B) each independently have a film forming ability. Ink receiving layer. 6. The ink receiving layer according to claim 1, wherein the printing method is an ink jet method, and the ink used is an aqueous pigment-based ink.