JPH106640A - Material for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for ink jet recording which has superior water ink receptivity, a good destatization properties and smooth traveling performance for paper supply in jet-recording in ink an OHP sheet with inferior printability shown when water ink is used. SOLUTION: A recording layer consisting of an ionomer thin film neutralized by an alkaline metal selected from ethylene containing 16-30wt.% of unsaturated carboxylic acid and potassium, rubidium and cesium which accounts for at least, 60% of the unsaturated carboxylic acid component of an unsaturated carboxylic copolymer, is formed on a base material, especially on a base material for film or sheet with inferior water ink receptivity of polyester or polyolefin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording material which is excellent in printability and running property when feeding paper. More specifically, the present invention relates to an ink-jet recording material which is capable of performing clear recording without ink bleeding, having a high ink absorption speed when recording is performed by an ink-jet method using an aqueous ink.

[0002]

2. Description of the Related Art A recording method using an ink jet method is as follows.
A color printer has come to be widely used as a representative example. Aqueous ink is used exclusively for such OA equipment, but polyethylene terephthalate sheet or polypropylene synthetic paper that is commonly used as an OHP (overhead projector) sheet,
Due to the low aqueous ink receptivity, printing cannot be performed as it is. Therefore, an ink receiving layer has been formed on these materials by applying a water-soluble resin such as polyvinyl alcohol so that printing can be performed with an aqueous ink.

By the way, at the time of feeding in the printing process, such recording materials may be overlapped or fed by charging. That is, the running property is poor. Conventionally, a surfactant type antistatic agent has been added to the ink receiving layer in order to prevent this charging. However, such a type of antistatic agent sometimes bleeds on the surface of the ink receiving layer when stored for a long period of time, resulting in a decrease in printability. Another problem is that the antistatic property does not last for a long time.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors
Avoid troubles caused by the use of surfactant-type antistatic agents,
In addition, studies were made to provide a recording material having excellent printability with an aqueous ink. As a result, a recording material having the following material as a thin film has excellent printability for aqueous ink,
Further, since the thin film itself is a material having good non-charging properties, it has been found that the running property during paper feeding is excellent, and the present invention has been reached.

[0005]

According to the present invention, there is provided a base material comprising 60 to 30% by weight of an unsaturated carboxylic acid component of an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 16 to 30% by weight.
The present invention relates to an ink jet recording material characterized in that a recording layer composed of a thin film of an ionomer is formed in which at least% is neutralized with an alkali metal selected from potassium, rubidium and cesium.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The ionomer used in the present invention is an ionomer of an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 16 to 30% by weight, preferably 18 to 25% by weight. . Here, as the unsaturated carboxylic acid, acrylic acid, methacrylic acid, maleic acid,
Examples thereof include fumaric acid, maleic acid, monoalkyl esters of fumaric acid, and maleic anhydride, and acrylic acid and methacrylic acid are particularly preferred. The ethylene / unsaturated carboxylic acid copolymer may be a copolymer obtained by copolymerizing a third monomer such as an acrylate, a methacrylate or a vinyl ester.

When the ethylene-unsaturated carboxylic acid copolymer has an unsaturated carboxylic acid content of less than 16% by weight, not only is it not easy to form an aqueous dispersion advantageous for use in forming a thin film, but also the printing characteristics are poor. In addition, it is not easy to form a thin film having good non-charging properties. Further, when an unsaturated carboxylic acid content exceeding 30% by weight is used,
It is not preferable because the water resistance of the thin film is deteriorated.

If the molecular weight of the ethylene / unsaturated carboxylic acid copolymer is too large, the storage stability of the aqueous dispersion, which is advantageous for forming a thin film, is impaired. Is not enough, so 1
It is preferable to use one having a melt flow rate of 10 to 1000 dg / min, particularly 30 to 500 dg / min at 90 ° C. and a load of 2160 g. Such ethylene
The unsaturated carboxylic acid copolymer can be produced by radical copolymerization under high temperature and high pressure, similarly to high pressure polyethylene.

The ionomer used in the present invention is an alkali metal ion selected from potassium, rubidium and cesium, and has a neutralization degree of 60% or more, preferably 80% or more. When the metal ion species in the ionomer is an alkali metal such as sodium or lithium, a thin film having excellent printability and antistatic properties cannot be formed. Further, a neutralization degree higher than the above range is not only necessary for developing printability and antistatic properties, but is also desirable from the viewpoint of the stability of an aqueous dispersion that can be used for forming a thin film. Particularly preferred ionomers are those in which potassium is the ionic species.

As the base material of the ink jet recording material of the present invention, various resins, paper, synthetic paper, metal and the like can be exemplified. In particular, the recording material of the present invention has poor acceptability of aqueous ink. Materials, i.e., films of hydrophobic resins such as polyester, polyolefin, polyamide, etc.
It is suitable as a recording layer for imparting printability to a substrate such as a sheet or synthetic paper.

The thickness of the thin film of the ionomer formed on such a substrate is preferably at least 0.01 μm in consideration of printability and antistatic properties, but an excessive thickness is not economical. About 1 to 20 μm is sufficient.

The ionomer thin film serving as the ink jet recording layer may be crosslinked to improve its water resistance.
For this purpose, a crosslinking agent that reacts with a carboxyl group such as an epoxy compound, a methylolated urea, an isocyanate compound, a melamine compound, and formalin, or an aqueous dispersion of a polymer compound having these reactive groups can act on the ionomer. In order to prevent slipping and improve printability, the ionomer thin film may contain a finely powdered inorganic compound such as silica, alumina or smectite, a wax, or a polyolefin-based aqueous dispersion as a slip agent.

In the present invention, various methods can be adopted for forming the above-mentioned ionomer thin film on the substrate. An aqueous dispersion of the ionomer is prepared, and the aqueous dispersion is applied to the substrate and dried. The method of forming the film is preferable because the film can be formed uniformly and thinly. To prepare such an aqueous dispersion of the ionomer, a method of stirring the ionomer and water in an autoclave at a temperature equal to or higher than the melting point of the ionomer, for example, 80 ° C. or higher, preferably 95 ° C. or higher, or A method of simultaneously performing neutralization and production of an aqueous dispersion by stirring the ethylene / unsaturated carboxylic acid copolymer as the base polymer and the compound of the above alkali metal in water at a high temperature and under high pressure. be able to.

The solid content in the aqueous dispersion is 10%.
It is desirably adjusted to about 70% by weight, especially about 20 to 40% by weight. That is, when the solid content is low, the coatability is reduced, while when the concentration is too high, the viscosity of the aqueous dispersion becomes too large and handling becomes difficult.

To apply the aqueous dispersion to the substrate, a method used for general plastic coating, for example, a method using a roll coater, a bar coater, a spray, an air knife coater, a brush, or the like, A method of dipping in an aqueous dispersion of an ionomer can be employed. In applying the aqueous dispersion, a surfactant, a thickener, a wetting agent, and the like can be added to the aqueous dispersion in order to improve coatability. Further, a slip agent such as the above-mentioned crosslinking agent or inorganic compound can be added to the aqueous dispersion. After application, the recording material having a uniform film can be obtained by evaporating water by heating and drying.

The thus obtained ink jet recording material of the present invention can form a clear image by an ink jet recording method using an aqueous ink. Aqueous inks that can be used for such purposes are already well known. For example, water and a dye or pigment as a colorant are essential components, and a water-soluble liquid for preventing drying and imparting dissolution stability, a surface tension adjuster, and a water-soluble agent for preventing deterioration of image quality and dispersing a pigment. An aqueous ink containing a polymer, a preservative, a fungicide, a pH adjuster, an ultraviolet absorber, an infrared absorber and the like can be used.

[0017]

According to the present invention, when an aqueous ink is used to print on the ink jet recording material of the present invention by the ink jet method, the ink absorbency, print quality and ink adhesion are excellent, and the antistatic property is maintained for a long time. In addition, since the surfactant does not bleed, excellent printing characteristics are guaranteed, and the running property during paper feeding is also good.

[0018]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples. The methods for measuring the types and physical properties of the components constituting the aqueous dispersion used in the examples are as follows.

1. Raw materials and additives (1) Ethylene / acrylic acid copolymer (EAA) manufactured by Mitsui DuPont Polychemicals Co., Ltd. Ethylene content: 80% by weight Acrylic acid content: 20% by weight MFR: 300 g / 10 min

(2) Neutralizing agent Ammonia 28-30% water (Kanto Chemical Co., Ltd.) Potassium hydroxide reagent special grade 86% purity (Kanto Chemical Co., Ltd.) Sodium hydroxide reagent special grade 97% purity (Kanto Chemical Co., Ltd.) Made)

(3) Inorganic compound additive (colloidal silica) "Snowtex UP" (manufactured by Nissan Chemical Industries, Ltd.) Particle size 40 to 300 nm Solid content concentration 20 wt%

(4) Cross-linking agent Water-soluble cross-linking agent having epoxy group "Denacol EX850" (manufactured by Nagase Kasei Co., Ltd.) Water-based urethane resin "Superflex 107" (Daiichi Kogyo Seiyaku Co., Ltd.)
Made)

2. Base material OHP sheet PET “XEROX” film (XEROX Co., Ltd.)
No.) V516

3. Measurement method of physical properties of raw resin and coating film obtained

(2) Ink receptivity: Printing was performed on a thin film formed on an OHP sheet using a bubble jet color printer manufactured by Canon Inc., and the printing quality and ink absorbency were visually evaluated in the following two stages. did.

(A) Printing quality ○: Printing ink dots are crushed ×: Printing ink dots are not crushed

(B) Ink absorbency ：: One minute after printing, the printed surface is not rubbed with a cloth. ×: One minute after printing, the printed surface is rubbed with a cloth.

(3) Adhesiveness of ink: The number of grids peeled off with a cellophane tape in a grid peeling test was measured.

(4) Non-Chargeability (Surface Resistivity) After the OHP sheet on which a thin film is formed is aged at a temperature of 23 ° C. and a relative humidity of 30% and 50% for 24 hours, the surface at each relative humidity is obtained. The resistivity was measured with a Mitsubishi Yuka High Resistivity Meter (HIRESTA-IP).

Example 1 10.5 L of distilled water was placed in a stainless steel autoclave having a capacity of 14.5 L and equipped with a stirrer.
3.5 kg of AA pellets, 570 g of potassium hydroxide
(A degree of neutralization: equivalent to 90 mol%) was charged (25 wt% as a solid content of the aqueous dispersion), and the temperature was increased by heating under stirring at a rotation speed of 13 / sec. Autoclave internal temperature is 120 ℃
After the temperature was raised to 20 ° C., stirring was continued at that temperature for 20 minutes, and then the autoclave was cooled under stirring, cooled to room temperature, and an aqueous dispersion of a potassium ionomer of an ethylene / acrylic acid copolymer stably dispersed in water was performed. I got a body. The aqueous dispersion was transparent, had a viscosity of 120 cp, an average particle size of 7 nm, and a pH of 11. This aqueous dispersion is treated with a 100 μm thick PET O
It was applied on a HP sheet with a bar coater so as to have a thickness of 1 μm, and dried at 100 ° C. for 1 minute with a drier. The physical properties such as printability and surface resistivity of the PET OHP sheet having the potassium ionomer thin film formed on the surface thus obtained were measured. Table 1 shows the results.

Example 2 A potassium ionomer thin film was formed on the surface of an OHP sheet in the same manner as in Example 1 except that the epoxy dispersion was added to the aqueous dispersion at a solid content of 3 wt%. Physical properties were measured in the same manner as in Example 1. Table 1 shows the results.

Example 3 Example 3 was carried out in the same manner as in Example 1, except that an aqueous urethane resin was further added at a solid content of 20 wt. Table 1 shows the results.

Example 4 A potassium ionomer thin film was formed on the surface of an OHP sheet in the same manner as in Example 2 except that colloidal silica having a solid content of 20 wt% was further added and stirred well. Physical properties were measured in the same manner as described above. Table 1 shows the results.

[Comparative Example 1] XEROX FILM No. 1 used as a substrate film in Examples was used. Physical properties of V516 were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 10.5 L of distilled water was placed in a stainless steel autoclave equipped with a stirrer and having a capacity of 14.5 L, and EA
3.5 kg of A pellet and 412 g of ammonia (neutralization degree: equivalent to 75 mol%) were charged (solid content of the aqueous dispersion: 25 wt%), and the temperature was increased with stirring at a rotation speed of 13 / sec. After the internal temperature of the autoclave was raised to 150 ° C., stirring was continued at that temperature for 60 minutes, and then the autoclave was cooled under stirring, cooled to room temperature, and ethylene / ethylene dispersed stably in water.
An ammonia ionomer dispersion of an acrylic acid copolymer was obtained. The aqueous dispersion is slightly white and has good transparency, and has a viscosity of 29.
0 cps, pH was 9.8. This aqueous dispersion was coated on a PET OHP sheet in the same manner as in Example 1 and dried, and physical properties such as printability and surface resistivity of the PET OHP sheet on which an ammonia ionomer thin film was formed were measured. Table 1 shows the results.

Comparative Example 3 10.5 L of distilled water was placed in a stainless steel autoclave equipped with a stirrer and having a capacity of 14.5 L.
3.5 kg of AA pellets, 360 g of sodium hydroxide
(Neutralization degree: equivalent to 90 mol%) was charged (25 wt% as the solid content of the aqueous dispersion), and the temperature was increased by heating under stirring at a rotation speed of 13 / sec. After the internal temperature of the autoclave was raised to 120 ° C. and stirring was continued at that temperature for 20 minutes, the autoclave was cooled under stirring, cooled to room temperature, and the ethylene-acrylic acid copolymer dispersed stably in water. An aqueous sodium ionomer dispersion was obtained. The aqueous dispersion was transparent, had a viscosity of 120 cp, an average particle size of 7 nm, and a pH of 11. This aqueous dispersion was treated with PET OHP in the same manner as in Example 1.
The OHP sheet made of PET coated and dried on a sheet to form a sodium ionomer thin film, printability,
Physical properties such as surface resistivity were measured. Table 1 shows the results.

[0037]

[Table 1]

As is evident from the results in Table 1, a thin film of the ionomer neutralized with potassium was obtained from a commercially available PET OH.
Compared to P sheet and ionomer coatings neutralized with other alkali metals, the printability of the aqueous ink is better, and the non-chargeability is excellent, so it is excellent as an inkjet recording material using the aqueous ink. Has physical properties.

Claims (3)

[Claims] 1. The method according to claim 1, wherein the base material has an unsaturated carboxylic acid content of 16%.
A recording layer composed of a thin film of an ionomer is formed in which 60% or more of the unsaturated carboxylic acid component of the ethylene / unsaturated carboxylic acid copolymer is neutralized with an alkali metal selected from potassium, rubidium and cesium. A material for ink jet recording, characterized in that it is made. 2. The ink-jet recording material according to claim 1, wherein the ionomer forming the thin film is cross-linked. 3. The ink-jet recording material according to claim 1, wherein a finely divided inorganic compound is blended in the thin film layer.