JPH11301100A - Manufacture of ink jet recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an ink receiving property and water resistance by applying a slurry having inorganic particles or the like suspended in solution of a hydrophobic inorganic binder or the like, drying it to form an ink receptor layer, and applying and drying a surface-active agent on the surface of the ink receptor layer. SOLUTION: An ink receptor layer is formed by applying and drying a slurry having inorganic particles and/or organic particles suspended in a solution of a hydrophobic inorganic binder and a surface-active agent on a transparent base material, and then, a solvent capable of dissolving a surface-active agent is applied on the surface of the ink receptor layer to be dried again. In this process, an ink jet recording material is obtained, which has a good ink receiving property and water resistance, and also has printings and images formed by ink jet rendered visible clearly even from the base material side. In this case as inorganic particles, calcium carbonate having a particle diameter of 1-20 μm in 50 wt.%, a BET specific surface area of 3-70 m<2> /g, and an oil absorption of 30-200 ml/100 g in used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a recording material for ink jet recording, and more particularly to a method for producing a recording material for ink jet recording which is excellent in ink receptivity and water resistance and in which prints and images formed by ink jetting are easily seen from the back surface. It is.

[0002]

2. Description of the Related Art Inkjet printers have been widely used for producing not only documents but also advertisements and other exhibits. The ink of the ink jet printer is a water-soluble ink in which a dye and various auxiliaries are mainly dissolved in water, and a recording material receiving the ink is provided with a coating layer of a water-soluble polymer compound on a base material. And those in which various particles are contained in the coating layer.

[0003]

One of the problems of the conventional ink jet recording material is that it has poor water resistance. That is, since the ink-receiving layer is mainly composed of a water-soluble polymer compound, a recorded matter formed with a water-based ink on the character or image, bleeds when contacted with water, and in severe cases, the recording layer itself is eluted. I will.

[0004] As one of measures against the problem of poor water resistance, a transparent film is attached to a recording surface. Although this method is effective as a method for ensuring water resistance for a long period of time, the operation of attaching a film is complicated. Recently, there has been a demand for a recording material suitable for the field of exhibiting advertisements and the like, which is required to satisfy durability for a relatively short period of about several months at most.

[0005] Further, the use of ink jet formed prints and images viewed from the base material side is also being studied. An opaque ink receiving layer is provided on a transparent base material suitable for this use. There is also a demand for a recording material on which formed prints and images can be clearly seen from the base material side. An object of the present invention is to provide a method for manufacturing a recording material that meets such requirements.

[0006]

According to the present invention, a slurry in which inorganic particles and / or organic particles are suspended in a solution in which a hydrophobic organic binder and a surfactant are dissolved in an organic solvent is formed by a transparent slurry. The ink receiving layer is formed by drying after coating on a substrate, and then applying a solvent capable of dissolving the surfactant to the surface of the ink receiving layer and then drying again to obtain an ink receiving property and water resistance. It is possible to manufacture a recording material for ink jet recording which is excellent in ink jet printing and in which prints and images formed by ink jet can be clearly seen from the base material side.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail. As a substrate for producing a recording material used in the present invention, a transparent substrate may be used among ordinary ones, and usually, polyester, polyethylene, polypropylene or the like is used. Plastic films such as polyvinyl chloride and the like, which have good water resistance and good handleability, among which polyethylene terephthalate films are preferred. The thickness of the substrate is usually 10
The thickness is from 150 to 150 μm, especially from 25 to 120 μm, and may be appropriately selected in consideration of the use and handling of the recorded matter.

In the present invention, a slurry in which inorganic particles and / or organic particles are suspended is applied to a solution in which a hydrophobic organic binder and a surfactant are dissolved in an organic solvent, and then dried. Thus, an ink receiving layer is formed.
Therefore, the formed ink receiving layer has a structure in which inorganic particles and / or organic particles are bound to a substrate with a hydrophobic organic binder.

As the hydrophobic organic binder, one that is soluble in an organic solvent is used. For example, polyvinyl butyral, polyester, acrylic resin, ethylene-vinyl acetate copolymer, polyetherimide, polysulfone, polyurethane and the like are used. Among them, it is preferable to use the polyester alone or a mixture of the polyester and a resin soluble in another organic solvent, the polyester occupying 50% by weight or more. As such a mixture, for example, a mixture of a polyester and 5 to 30% by weight of a polyacrylate is used. This gives an ink-receiving layer with better ink absorption than the polyester alone. Since water resistance tends to decrease when a polyacrylic acid ester is blended, a water resistance improver such as magnesium stearate is preferably used in an amount of 2 to 30% by weight based on the binder.

As the surfactant, any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant and a nonionic surfactant can be used. Among them, an anionic surfactant or a cationic surfactant is preferable. It is preferred to use the activators alone or in combination.
Generally, it is preferable to use both. As these surfactants, commonly used surfactants such as sodium alkylbenzenesulfonate, sodium alkanesulfonate, sulfates of higher alcohols, amines having long-chain alkyl groups and quaternary ammonium salts can be used. The surfactant is generally used in an amount of 0.1 part by weight or less per 100 parts by weight of the hydrophobic organic binder. It is considered that the surfactant promotes the movement of the ink in the ink receiving layer during recording. However, if the amount of the surfactant is too large, bleeding occurs due to the lateral diffusion of the ink during recording,
The water resistance of the formed recorded matter is reduced, so that the ink easily oozes out when wet with water. The surfactant is generally used in an amount of 0.01 to 0.1 per 100 parts by weight of the hydrophobic organic binder.
It is preferably used so as to be 0 parts by weight, particularly 0.02 to 0.06 parts by weight.

The inorganic particles include calcium carbonate, silica, diatomaceous earth, aluminum silicate, magnesium silicate, calcium silicate, alumina, zeolite, barium sulfate,
Calcium sulfate or the like is used. These may be used alone or in combination. Especially, it is preferable to use calcium carbonate which is excellent in ink absorbency. Calcium carbonate can be used alone or in combination with other inorganic particles other than calcium carbonate. Even in such a case, it is preferable that at least 50% by weight of calcium carbonate is calcium carbonate. The calcium carbonate generally has a particle size of 1 to 20 μm, preferably 2 to 8 μm, and a specific surface area by BET method of 3 to 70 m ² / g, preferably 5 to 50 m ² / g.
m ² / g, oil absorption by JIS K-5421 method is 30
~ 200ml / 100g, preferably 50 ~ 170ml
/ 100 g is used.

Particularly preferred as the inorganic particles are aragonite calcium carbonate. This is a needle-like crystal, and it is preferable to use a crystal having a needle-like or sea urchin shell-like appearance in which the needle-like crystals are entangled. When aragonite calcium carbonate is used, an ink receiving layer having high surface hardness and high strength can be formed. This is probably because the particles are entangled with each other due to the specificity of the particle structure. The aragonite calcium carbonate generally has a particle size of 1 to 20 μm, preferably ² to 8 μm, and a BET specific surface area of 3 to 70 m ² /
g, preferably 5 to 50 m ² / g, JIS K-542
The oil absorption by the method 1 is 30 to 200 ml / 100 g, preferably 50 to 170 ml / 100 g.

The aragonite calcium carbonate may be used in combination with other inorganic particles as described above, if desired.
Even in that case, it is preferable that at least 50% by weight of the inorganic particles is aragonite calcium carbonate. As the inorganic particles to be used in combination, the above-mentioned porous calcium carbonate is preferable. For example, inorganic particles in which aragonite calcium carbonate is 50% by weight or more and at least a part of the remaining inorganic particles is the above-described porous calcium carbonate The combination of
This is one of the preferred embodiments of manufacturing a recording material according to the present invention.

[0014] As the organic particles, acrylic resin, urea resin, melamine resin, phenol resin, styrene resin and the like are used. Among them, it is preferable to use a urea resin. The urea resin has a particle size of 0.1 to 50 μm, particularly 1 μm.
5 μm, oil absorption by JIS K-5101 method is 20
0-1500ml / 100g, especially 400-1100m
It is preferable to use 1/100 g. Usually, a urea resin is used alone. Of course, other substances can be used in combination, but even in this case, at least 50% by weight of the organic particles is used.
It is preferable to use a urea resin.

[0015] The inorganic particles and the organic particles can be used alone or in combination. When each of the inorganic particles and the organic particles is used alone, it is preferable to use these particles in an amount of 30 to 200 parts by weight, particularly 50 to 180 parts by weight, based on 100 parts by weight of the hydrophobic organic binder. When both are used in combination, it is preferable to use inorganic particles and organic particles in a total amount of 30 to 220 parts by weight, particularly 50 to 180 parts by weight, based on 100 parts by weight of the hydrophobic organic binder. The mixing ratio (weight ratio) of inorganic particles and organic particles
Is preferably from 20:80 to 80:20.

In either case where the inorganic particles and the organic particles are used alone or in the case where both are used in combination, if the ratio of these particles to the hydrophobic organic binder is too small, the ink of the ink receiving layer to be formed is formed. As a result, the ink receptivity decreases, and as a result, it takes a long time to dry the ink at the time of recording, and in extreme cases, the ink dripping occurs. In addition, the formed recorded matter also has low water resistance, and ink bleeds easily when wet with water. This is because the ink should be absorbed and retained in the gap between the particles and the pores in the particle, so that the ratio of the particle to the hydrophobic organic binder is too small and a considerable part of the particle surface is Is considered to be due to the fact that the ink is covered with the hydrophobic organic binder or the gaps between the particles are filled with the hydrophobic organic binder, whereby the absorption of the ink is hindered and the ink is kept on the hydrophobic organic binder.
On the other hand, if the ratio of the particles to the hydrophobic organic binder is too large, the adhesive strength of the particles is weak, and powder dropping of the particles from the ink receiving layer occurs. In addition, the ink absorption may be too good at the time of recording, and a desired density or color tone may not be obtained.

The ink receiving layer is formed by dissolving the above-mentioned hydrophobic organic binder and surfactant in an organic solvent, and suspending the solution by adding particles selected from the group consisting of inorganic particles and organic particles. Is applied to a substrate and dried. Any organic solvent may be used as long as it dissolves the hydrophobic organic binder and does not dissolve these particles, and it is preferable to use a solvent having a relatively low boiling point so as to be easily dried. Generally, general-purpose solvents such as methyl ethyl ketone, isopropyl alcohol, toluene, methyl isobutyl ketone, ethyl acetate, butyl acetate, cyclohexanone, and xylene are used.

In the slurry for forming the ink receiving layer,
If desired, various auxiliaries such as a dispersant, an ultraviolet absorber, a light stabilizer, a thickener, a defoamer, a dye, and a fluorescent brightener may be added. For example, as an ultraviolet absorber or a light stabilizer for improving weather resistance, ordinary hindered amines,
A benzotriazole-based, benzophenone-based, benzoate-based compound, or the like may be used alone or in combination.

The slurry can be applied onto the substrate by any conventional coating method such as bar coating, blade coating, die coating, reverse roll coating, and gravure roll coating. The dry coating thickness, that is, the thickness of the ink receiving layer is 10 to 100 μm, particularly 20 to 80 μm.
It is preferred that If the ink receiving layer is too thin, the ink absorbency and fixability at the time of recording are poor, causing ink dripping, and the formed printed matter has poor water resistance, and the ink oozes out when wet with water. Get up. In addition, in order to enhance the adhesiveness between the ink receiving layer and the base material, an adhesive layer may be formed on the base material by coating, and the ink receiving layer may be formed thereon.

In the present invention, after the slurry for forming the ink receiving layer is applied on the substrate as described above, and the organic solvent is evaporated to form the ink receiving layer, the slurry is then used for the ink receiving layer. A solvent that dissolves the surfactant is applied and dried again. The application can be performed in the same manner as the application of the slurry described above. By applying and drying the solvent on the ink receiving layer, prints and images formed on the formed ink receiving layer by inkjet can be clearly seen from the base material side. Although the reason is not clear, it is considered that the surfactant moves in the receiving layer. That is, in a process in which the solvent applied to the surface of the ink receiving layer permeates the inside of the ink receiving layer toward the base material, the surfactant in the ink receiving layer dissolves in the solvent and moves together. Therefore, the concentration of the surfactant on the surface side of the ink receiving layer decreases, and conversely, the concentration on the substrate side increases. When printing is performed by ink jet on the ink receiving layer having a surfactant concentration distribution in which the surface side is low and the substrate side is high, the ink is guided by the surfactant and easily penetrates into the ink receiving layer. I do. As a result, the density of the ink on the substrate side of the ink receiving layer is increased as compared with the case where printing is performed on the ink receiving layer where the surfactant is uniformly distributed, and the formed print or image is It is thought that it becomes clear from the substrate side.

As a solvent applied to the ink receiving layer, any solvent can be used as long as it can easily dissolve the used surfactant. For example, a common solvent such as ethylene glycol, xylene, isopropyl alcohol, and water can be used. Preferably, an organic solvent having a high solubility in a surfactant and a relatively low boiling point is used. For example, it is preferable to use isopropyl alcohol or a mixture of isopropyl alcohol and another solvent in which isopropyl alcohol accounts for 50% by weight or more.

The amount of the solvent to be applied varies depending on the composition of the slurry used for forming the ink receiving layer, but is usually 150% by weight based on the total amount of the hydrophobic organic binder and the inorganic particles and / or the organic particles constituting the ink receiving layer. Hereinafter, it is preferably 20 to 100% by weight. If the coating amount is small, probably because the movement of the surfactant in the ink receiving layer is insufficient,
The print or image formed by the ink jet does not become clearly visible from the substrate side. Conversely, even if the coating amount is too large, the print or image does not become clearly visible from the base material side,
Moreover, bleeding is likely to occur due to the lateral diffusion of the ink. This is because the ink receiving layer is filled with the solvent and the concentration distribution of the surfactant is not formed in the ink receiving layer,
Conversely, it is considered that when this solvent evaporates, the solvent containing the surfactant inside the receiving layer moves to the surface and the concentration of the surfactant at the surface increases.

An adhesive is optionally applied to the substrate surface opposite to the ink receiving surface of the recording material manufactured by the present invention, and the recording material is covered with a release paper. It is convenient when applied to the transparent substrate surface from the inside and used for observation from the outside.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Production of an ink jet recording material; a mixed solution of a hydrophobic polyester resin in toluene and methyl ethyl ketone (Polyester LP-044 manufactured by Nippon Synthetic Chemical Co., Ltd.)
Aragonite calcium carbonate (manufactured by Shiraishi Kogyo Co., Callite SA, average particle size 3.3)
μm, BET specific surface area 8-10 m ² / g, JIS K5
421, an urea-formaldehyde resin (manufactured by Nippon Kasei Co., organic filler, average particle size 3.8 μm) and a surfactant were added, and the mixture was stirred well to obtain a slurry having a uniform composition. This slurry was applied to a transparent biaxially stretched polyethylene terephthalate film having a thickness of 100 μm so as to have a dry film thickness of 40 μm, and dried to form an ink receiving layer. The surface of the ink receiving layer was smooth.

The surface of the ink receiving layer was coated with isopropyl alcohol and 100 parts by weight of the ink receiving layer.
And dried in a dryer at 90 ° C. for 3 minutes. The surface of the ink receiving layer was smooth and no change was observed.

Evaluation of ink jet recording material: The following items were evaluated for the ink jet recording material produced above. The results are shown in Table 1.

(1) Color Density of Surface and Substrate Side of Image After the recording material is left in an atmosphere of a temperature of 23 ° C. and a humidity of 55% for 24 hours, an ink jet printer (a product of Sharp Corporation, Using IO-735), printing was performed using commercially available pigment-based aqueous inks of cyan, yellow, and magenta. Regarding the formed image, a reflection color density meter (manufactured by Nippon Denshoku Industries Co., Ltd., Macbeth RD91)
Using 8), the reflection color density was measured from the ink receiving layer side and the substrate side.

(2) Ink bleeding and drying during recording The bleeding state of the ink was observed during the above printing, but no bleeding was observed in any case. Also, cyan + yellow,
Overprinting of cyan + magenta and yellow + magenta was performed, and the absorption and drying properties of the ink were observed. The results are shown below.

A: The ink was absorbed within 30 seconds, and the surface of the printing portion became dry. ：: The ink was absorbed within 50 seconds, and the surface of the printing portion became dry.

(3) Quality Stability A recording material was cut into 298 × 210 mm (A4 size) to obtain a sample. The sample was allowed to stand in an atmosphere at a temperature of 23 ° C. and a humidity of 55% for 24 hours, followed by printing in the same manner as described above, and further allowed to stand in the same atmosphere for 24 hours. This sample was stored in a constant temperature / humidity tester at a temperature of 50 ° C. and a humidity of 80% with the ink receiving surface facing up and left for 24 hours. Then, the ink was similarly received in a vacuum dryer at a temperature of 50 ° C. and a degree of vacuum of 760 mmHg. The operation of housing the device with the surface facing upward and leaving the device to stand for 12 hours was repeated 5 times. However, no curling, lack of the ink receiving layer, and bleeding of the print were observed.

(4) Concealment The recording material was cut into 298 × 210 mm (A4 size) to obtain a sample. This sample was left in an atmosphere at a temperature of 23 ° C. and a humidity of 55% for 24 hours, and then printed in the same manner as described above. Indoor fluorescent lamp (Mitsubishi Electric products, KVK4322,
Neolumi Super FLR40S ・ W / M)
mm, the printed recording paper was placed 20 mm away from the fluorescent lamp, and the printed surface was directed toward the fluorescent lamp. When observed from the substrate side in this state,
All of them were cloudy as a whole, and the prints could be clearly identified, but the fluorescent lamps could not be identified, and had sufficient concealing properties.

[0033]

[Table 1]

[0034]

[Table 2]

As is apparent from Table 1, in the examples in which the solvent was applied to the ink receiving layer according to the method of the present invention and dried, the difference in the reflection color density between the ink receiving layer side and the substrate side was small. However, in the case of the comparative example in which this processing is not performed, there is a large difference in the reflection color density between the two.

Claims (11)

[Claims] 1. A method in which a slurry in which inorganic particles and / or organic particles are suspended in a solution in which a hydrophobic organic binder and a surfactant are dissolved in an organic solvent is applied onto a transparent substrate and then dried. A method for producing an ink jet recording material, comprising forming an ink receiving layer, applying a solvent capable of dissolving the surfactant to the surface of the ink receiving layer, and then drying the solvent. 2. At least 50% by weight of the inorganic particles is calcium carbonate having a particle size of 1 to 20 μm, a BET specific surface area of 3 to 70 m ² / g, and an oil absorption of 30 to 200 ml / 100 g. The method for producing a recording material for an inkjet according to claim 1. 3. Aragonite calcium carbonate having a particle diameter of 1 to 20 μm, a BET specific surface area of 3 to 70 m ² / g and an oil absorption of 30 to 200 ml / 100 g, at least 50% by weight of the inorganic particles. The method for producing an inkjet recording material according to claim 1, wherein: 4. At least 50% by weight of the organic particles have a particle size of 0.1 to 50 μm and an oil absorption of 200 to 1500 ml / l.
4. The method for producing an inkjet recording material according to claim 1, wherein the urea resin is 00 g. 5. The method according to claim 1, wherein at least 50% by weight of the hydrophobic organic binder is a polyester resin. 6. The method according to claim 1, wherein the slurry is a hydrophobic organic binder.
30 to 2 in total of the inorganic particles and the organic particles per 0 parts by weight.
The recording material for inkjet according to any one of claims 1 to 5, wherein the recording material is 20 parts by weight and the weight ratio of the inorganic particles to the organic particles is 20:80 to 80:20. Manufacturing method. 7. The method according to claim 1, wherein the slurry is a hydrophobic organic binder.
The method according to any one of claims 1 to 6, wherein a surfactant is contained in an amount of 0.01 to 0.10 part by weight per 0 part by weight. 8. The method for producing an ink jet recording material according to claim 1, wherein the surfactant is an anionic surfactant and / or a cationic surfactant. . 9. The ink jet recording material according to claim 1, wherein the amount of the solvent applied to the ink receiving layer is 20 to 100% by weight of the ink receiving layer. Production method. 10. The ink-jet recording material according to claim 1, wherein the solvent applied to the ink receiving layer is isopropyl alcohol or a mixed solvent containing 50% by weight or more of isopropyl alcohol. Manufacturing method. 11. The ink receiving layer has a thickness of 10 to 100 μm.
The method for producing a recording material for an ink jet according to any one of claims 1 to 10, wherein m is m.