JPH08176428A - Composition for ink-accepting layer - Google Patents

Abstract

PURPOSE: To obtain a compsn. which forms an ink-accepting layer excellent in writing properties, printability, ink drying, water resistance, etc., by mixing an ultraviolet-cole resin, a specific hydrophilic polymer, and a filler. CONSTITUTION: The compsn. for an ink-accepting layer is prepd. by mixing an ultraviolet-curable resin (e.g. a resin comprising an acryloyl-group-contg., free-radical-polymerizable acrylate resin and a photoinitiator generating free radicals when exposed to ultraviolet rays), a hydrophilic polymer sol. in the ultravolet-curable resin and mainly comprising ethylene oxide units and/or propylene oxide units (e.g. polyethylene glycol), and a filler (e.g. calcium carbonate). After the compsn. is cured, fine particles of the hydrophilic polymer precipitate and disperse in the ultraviolet-curable resin, facilitating the writing or printng on the ink-accepting layer with a water-base pen or an ink jet printer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible to easily write and print with a water-based ink or the like on a material which cannot be easily recorded with a water-based felt-tip pen or ink jet printer. The present invention relates to a composition for an ink receiving layer.

[0002]

2. Description of the Related Art Polycarbonate resin, vinyl chloride resin, polyethylene terephthalate resin, polystyrene resin, ABS resin and the like are used as cards, sheets and containers. When characters or symbols are recorded on these resin surfaces with an aqueous ink, I can't write well because cissing occurs, the drying speed is slow, and it easily comes off when rubbed by hand. Therefore, conventionally, an aqueous resin or a composition comprising an aqueous resin and a filler has been applied to the resin surface. However, when an aqueous resin is used for the ink receiving layer, recording is possible but the water resistance is poor, and the ink diffuses over time, causing the recording to bleed or disappear, which is not preferable. Further, it takes a long time to dry, and there is a problem in productivity. On the other hand, as an ink receiving layer having improved water resistance, a compound in which a large amount of a filler such as silica is mixed with a resin soluble in an organic solvent is used. In this case, the water resistance is certainly good, but it takes time to dry the organic solvent, and a method that does not use the organic solvent has been desired from the viewpoint of productivity.

From the viewpoint of productivity, it is preferable to use an ultraviolet curable resin which does not use any solvent. Then, various studies using ultraviolet curable resins have been conducted. Generally, the improvement of the drying speed of the water-based ink is achieved by increasing the amount of the filler or by increasing the hydrophilicity of the ultraviolet curable resin which is the matrix phase, but increasing the amount of the filler increases the viscosity of the composition and the coating work. Sex matters. Therefore, for example, Japanese Patent Application No. 6-247882 relating to the proposal of the present invention discloses a composition containing an ultraviolet-curable resin and an organic and / or inorganic filler having water-absorbing and / or oil-absorbing property, and a hydrophilic polymer in a matrix phase. Further, the hydrophilicity of the matrix phase is increased by using a hydrophilic monomer. However, increasing the hydrophilicity of the matrix phase lowers the water resistance, which is not preferable. When the UV curable resin is used as described above, there is a trade-off between the drying property of the ink and the water resistance. When the drying speed of the ink is increased, the water resistance is deteriorated. Conversely, when the water resistance is improved, the ink drying property is improved. Is reduced.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have used an ultraviolet curable resin and have excellent writability with a water-based ink (that is, a fast drying speed, which does not bleed or disappear over time) and excellent water resistance. As a result of intensive studies on the development of the ink receiving layer, the present invention has been completed.

[0005]

Means for Solving the Problems That is, the present invention provides (1)
A composition for an ink-receiving layer comprising an ultraviolet curable resin, a hydrophilic polymer obtained by polymerizing ethylene oxide and / or propylene oxide dissolved in the ultraviolet curable resin as a main component, and a filler, wherein the composition is cured. The composition for an ink receiving layer is characterized in that the hydrophilic polymer is dispersed in the ultraviolet curable resin in the form of fine particles after the treatment. (2) The ultraviolet curable resin is 95 to 50% by weight, and is hydrophilic. 50 to 5% by weight of the hydrophilic polymer and 5% of the filler with respect to 100 parts by weight of the ultraviolet curable resin and the hydrophilic polymer.
(50) The composition according to (1), which comprises 50 parts by weight,
The molecular weight of the hydrophilic polymer is 500-50,000 (2)
(4) An ink-receiving layer obtained by curing the composition according to any one of (1) to (3).

In the composition of the present invention, it is possible to provide an ink receiving layer which is excellent in writability and water resistance without increasing the viscosity of the composition. The drying property of the ink can be increased by increasing the amount of the filler used as described above, but when a large amount of the filler is used, the viscosity of the composition increases, which leads to a reduction in coating workability and is not preferable. , The amount of filler cannot be increased unreasonably. However, in the present invention, when the composition is cured, the hydrophilic polymer in the composition is finely dispersed and precipitated in the ultraviolet curable resin. Since the particulate hydrophilic polymer dispersed and deposited absorbs the ink, the drying property of the ink becomes sufficiently fast without increasing the amount of the filler in a large amount. On the other hand, in the uncured state, the hydrophilic polymer is dissolved in the UV curable resin. However, among the hydrophilic polymers, the polymer obtained by using polyethylene oxide and / or propylene oxide as a main component has a low viscosity as compared with other hydrophilic polymers, and thus the composition of the present invention has a low viscosity. Is small and the coating workability is excellent. From the viewpoint of coating workability, the molecular weight of the hydrophilic polymer is preferably 500 to 50,000, 1,000 to 1
More preferably, it is about 000.

Specific examples of the hydrophilic polymer used in the present invention include polyethylene glycol obtained by polymerizing ethylene oxide, polypropylene glycol obtained by polymerizing propylene oxide, and copolymers of ethylene oxide and propylene oxide. Is mentioned. The ends of these polymers are usually hydroxyl groups,
The hydroxyl group may be used as it is, or may be modified with an acryloyl group or an epoxy group which is copolymerized with an alkoxy group or an ultraviolet curable resin. In particular, when the composition of the present invention is cured, in order to prevent the hydrophilic polymer and the ultraviolet curable resin from separating into two layers, and to make them into a dispersed state as fine particles in the ultraviolet curable resin, the hydrophilic property as described above is used. It may be preferable that the terminal of the polymer is modified as described above because it is better dispersed.

The UV-curable resin used in the present invention is not particularly limited, and a radical polymerization type so-called (meth) acrylate compound having one or more known acryloyl groups and / or methacryloyl groups in the molecule and From a resin consisting of a resin and a photoinitiator that generates radicals by irradiation with ultraviolet rays, a radical polymerization type epoxy compound and resin having one or more epoxy groups, a vinyl ether monomer and a photoinitiator that generates cations by irradiation of ultraviolet rays And the like. More specific examples of the (meth) acrylate-based compound and resin, the epoxy-based compound and resin, the vinyl ether-based monomer and the photoinitiator used for the UV curable resin include, for example, "UV / BE curing technology" issued by General Technology Center Co., Ltd. And known compounds and resins and photoinitiators described in "In fact, technology of new photosensitive resin" issued by CMC Co., Ltd. At this time, a non-reactive resin that forms a uniform matrix phase may be used together if necessary.

Specific examples of such non-reactive resin include:
Examples thereof include acrylic resin, vinyl acetate resin, polyvinyl alcohol resin, polystyrene resin, polyvinylpyrrolidone resin, vinylpyrrolidone-vinyl acetate copolymer resin, butyral resin, hydroxyethyl cellulose, nitrocellulose, and methylcellulose.

In the present invention, what is important in selecting the ultraviolet curable resin is that it is necessary to select a resin that dissolves the hydrophilic polymer in the uncured state and does not dissolve the hydrophilic polymer after curing. is there. If the hydrophilic polymer is dissolved even after curing to form a uniform coating film, the drying property of the water-based ink will not be accelerated. As described in the above-mentioned literature, there are various ultraviolet curable resins, for example, hydrophilic ones having a low molecular weight and a hydroxyl group to lipophilic ones, which are cured depending on the kind of the hydrophilic polymer used in the present invention. The UV curable resin may be selected so that the hydrophilic polymer is dissolved before and the hydrophilic polymer is not dissolved after curing. The preferable combination or the combination that can be used can be easily determined experimentally depending on whether or not it becomes cloudy. The term "dissolution" used here means
It suffices that the hydrophilic polymer is substantially dissolved.Before curing, a part of the hydrophilic polymer is dispersed in the UV curable resin due to the solubility without being dissolved to the extent that two-phase separation or the like does not occur. Is also good. At this time, a solvent may be used in combination in order to assist the solubility of the hydrophilic polymer in the ultraviolet curable resin. Further, after curing, a part of the hydrophilic polymer may be dissolved in the ultraviolet curable resin. On the contrary, a part of the ultraviolet curable resin may be dissolved in the hydrophilic polymer.

In the present invention, as described above, the hydrophilic polymer is dissolved in the UV curable resin before being cured, but the hydrophilic polymer and the UV ray are so dissolved as not to be dissolved in the UV curable resin after being cured. Select a cured resin. The determination method can be performed as follows, for example. Before curing, whether or not insoluble matter is present in the mixture solution of the hydrophilic polymer and the UV curable resin, or whether the solution is cloudy, whether it is a single solution of the UV curable resin, visually or turbidity Can be determined by measuring At this time, as described above, there are cases where a part of the hydrophilic polymer is dispersed in the ultraviolet curable resin due to the solubility, and in this case, the mixture may become cloudy. It can be determined by reducing the addition ratio. On the other hand, after curing, it can be determined whether or not the cured resin is cloudy, or by observing the cured resin with an optical or electron microscope. In the observation with a microscope, it may be easier to judge by observing the dispersed hydrophilic polymer phase or the matrix resin phase by dyeing with a known method. If it is difficult to make a judgment due to the influence of the filler, the judgment can be made easier by observing in a system without the filler.

Examples of the filler used in the present invention include water-absorbing and / or oil-absorbing organic and / or inorganic fillers. Specific examples of these fillers include:
For example, synthetic silica, talc, clay, calcium carbonate, calcium silicate, barium sulfate, mica, diatomaceous silica, aluminum hydroxide, alumina, zirconium oxide, inorganic fillers such as zirconium hydroxide and acrylic resin particles, melamine resin particles, Phenolic resin particles,
Examples thereof include organic fillers such as benzoguanamine resin particles, crosslinked polystyrene resin particles, cellulose powder, protein particles and lignin powder. These organic fillers may be crosslinked. These inorganic and organic fillers are preferably those in which fine primary particles are aggregated to form secondary particles, particles having microscopic voids, and particles having hydrophilicity. Further, these fillers may be mixed and used. The particle size of the filler used is not particularly limited, but is usually about 30 to 0.1 μ.

The ratio of various components used in the composition of the present invention is such that the ratio of the ultraviolet curable resin and the hydrophilic polymer is such that the ultraviolet curable resin is 95 to 50% by weight, preferably 90 to 60% by weight,
The hydrophilic polymer is 50 to 5% by weight, preferably 40 to 10 parts by weight. UV curable resin is too large, for example 95
If it exceeds 5% by weight, the drying property of the ink becomes slower.

On the other hand, the filler is used in an amount of 5 to 50 parts by weight, preferably 15 to 40 parts by weight, based on 100 parts by weight of the ultraviolet curable resin and the hydrophilic polymer. When the amount of the filler is too large, for example, when it exceeds 50% by weight, the viscosity of the composition becomes too high and the coating workability is deteriorated.
On the contrary, if the amount is too small, for example, less than 5% by weight, the drying property of the ink is lowered, which is not preferable.

The composition of the present invention contains a thixotropic agent, a cissing inhibitor, an antifoaming agent, a leveling agent, a coloring dye or pigment, a silane coupling agent, and a luster in order to improve coating workability and coating film performance. An eraser, a plasticizer, a dispersant, an anti-settling agent, a thickener and the like may be added. Further, a solvent can be partially used.

The composition of the present invention is prepared by mixing an ultraviolet curable resin, a hydrophilic polymer and a filler. To disperse the filler uniformly, for example, a disperser (disperser),
A known mixer such as a three-roll mill, a grinder or a homomixer is used.

The method of applying the composition of the present invention varies depending on the shape of the object, but for example, screen printing, roll coating, knife coating, etc. are generally used. The thickness of the coating layer is usually about 1 to 50 .mu.m, and the coating film can be easily cured by irradiation with ultraviolet rays to form an ink receiving layer.

By forming an ink receiving layer comprising the composition of the present invention, it is difficult to write or print, especially on an aqueous pen or an ink jet printer such as on the surface of plastic or metal, for example, OHP paper or plastic card. By applying to the surface of, it becomes possible to write with an aqueous pen or print with an inkjet printer. Further, for example, by forming the ink receiving layer of the present invention on the surface opposite to the light incident surface of the single-plate write-once type optical recording medium, the surface of the cartridge of the floppy disk, or the surface of the case, an inkjet printer can be used for these. You will be able to print the label and recorded contents.

[0019]

EXAMPLES Examples of the present invention will be shown below. [Example 1] 20% by weight of polyethylene glycol having a molecular weight of 1000 as a hydrophilic polymer, 50% by weight of 2-hydroxypropyl acrylate, 15% by weight of trimethylolpropane triacrylate, and 5% by weight of Durcure 1173 (product of Ciba-Geigy) as a photoinitiator. And a resin solution 100 consisting of vinylpyrrolidone-vinyl acetate (70:30) copolymer 10% by weight
20 parts of silica was added to parts by weight and mixed with a homomixer to prepare an ink-receiving layer composition. Next, the composition for the ink receiving layer is screen-printed using a 250-mesh screen on the protective layer of a single-plate type optical recording medium (Mitsui Toatsu Chemicals, Inc., Airy) and cured by irradiation with ultraviolet rays. Then, an ink receiving layer of 10 μm was provided on the entire surface of the medium. The resin solution was transparent and the polyethylene glycol was uniformly dissolved. The coating film obtained by applying and curing the resin solution was slightly cloudy. This cloudiness is a dispersion of polyethylene glycol in the UV curable resin in the form of particles due to curing. As a precaution, a solution obtained by removing polyethylene glycol from the resin solution was applied and cured, but the coating film was transparent. A label was printed on the medium provided with the ink receiving layer using an ink jet printer. There was no cissing or bleeding of the ink and good printing was possible. Also, the ink drying time is 25
It was seconds. In order to examine the water resistance of this printed matter, it was immersed in water at 25 ° C. for 1 hour, but no ink drop or bleeding occurred.

[Comparative Example 1] In the ink-receiving layer composition of Example 1, a composition for an ink-receiving layer was prepared without using polyethylene glycol, and evaluated in the same manner as in Example 1. The ink drying speed was 5 minutes, and when the printed matter was dipped in water, ink bleeding and falling occurred.

[Comparative Example 2] In the ink-receiving layer composition of Example 1, a vinylpyrrolidone / vinyl acetate copolymer resin was added in place of polyethylene glycol to prepare an ink-receiving layer composition. It evaluated by the same method as 1. The ink drying speed was 3 minutes, and when the printed matter was dipped in water, ink bleeding and falling occurred.

[Examples 2 to 4] Compositions for ink receiving layer were prepared and evaluated in the same manner as in Example 1 except that the hydrophilic polymers shown in Table 1 below were used instead of the polyethylene glycol of Example 1.

[0023]

[Table 1]

Even if any hydrophilic polymer is used,
The resin solution was transparent and the hydrophilic polymer was dissolved.
When only the resin solution was cured, the coating film was slightly clouded and the hydrophilic polymer was deposited in the form of fine particles. Further, the cured coating films of the solution obtained by removing the hydrophilic polymer from the resin solution were all transparent.

Example 5 Example 1 The composition for the ink receiving layer was applied to a polyethylene terephthalate film for an overhead projector by using a doctor blade and then irradiated with ultraviolet rays to be cured to form an ink receiving layer. . The thickness of the ink receiving layer was 10 μm. The film provided with the ink receiving layer was printed using an ink jet printer. There was no cissing or bleeding of the ink and good printing was possible. Good writing was also possible with a water-based felt-tip pen.

[0026]

EFFECT OF THE INVENTION The composition for the ultraviolet curable ink receiving layer of the present invention is dissolved in the uncured state, but after curing, ethylene oxide and / or ethylene oxide which precipitates in the matrix phase ultraviolet curable resin in the form of fine particles. By using a hydrophilic polymer obtained by polymerizing propylene oxide, the ink receiving layer formed by curing the composition can be easily written or printed by an aqueous pen or an inkjet printer, and the ink drying property can be improved. And excellent in water resistance.

Claims (4)

[Claims] 1. A composition for an ink receiving layer, comprising an ultraviolet curable resin, a hydrophilic polymer obtained by polymerizing ethylene oxide and / or propylene oxide soluble in the ultraviolet curable resin as a main component, and a filler. The composition for an ink receiving layer, wherein the composition is one in which the hydrophilic polymer is dispersed in the ultraviolet curable resin in the form of fine particles after curing. 2. The ultraviolet curing resin is 95 to 50% by weight, the hydrophilic polymer is 50 to 5% by weight, and the filler is 5 to 50 parts by weight based on 100 parts by weight of the ultraviolet curing resin and the hydrophilic polymer. The composition according to 1. 3. The hydrophilic polymer has a molecular weight of 500 to 50,000.
The composition according to claim 2, which is: 4. An ink receiving layer obtained by curing the composition according to claim 1.