JPS62222886A - Recording medium - Google Patents

Abstract

PURPOSE:To enhance ink absorbability, fixing property, surface glossiness, water resistance and lightfastnes etc., by providing a porous ink pervious layer and an unporous ink holding layer and setting the void ratio of the ink pervious layer to 0.2-0.75. CONSTITUTION:Because recording is performed on an ink pervious layer being a recording side by a recording liquid and a recording image is observed from an ink holding layer being an observation side, it is necessary that the ink pervious layer has high affinity to the recording medium in the recording liquid and low affinity to a recording agent while, because the ink holding layer absorbs and catches the recording liquid temporarily absorbed by the ink pervious layer, the absorbing force to the recording liquid is stronger than that of the ink pervious layer and the affinity to the recording liquid is high. In order to obtain a high grade and high quality image having good ink absorbability, it is necessary to set the void ratio of the ink pervious layer to 0.2-0.75 and, in order to control the void ratio, the particle size of particles and the mixing ratio of particles and a binder are adjusted to set the mixing wt. ratio of the particles and the binder to the range of particle/binder=1/3-50/1, more pref., 3/1-20/1.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a recording material suitable for a recording method using a recording liquid, such as a felt pen, a fountain pen, a pen plotter, an inkjet recording device, etc. The present invention relates to a recording material suitable for high-quality recording that has excellent absorbency and color properties of recorded images.

[Prior Art] Conventionally, recording methods using recording liquid, such as felt-tip pens,
Recording materials used for writing with a fountain pen or ballpoint pen, or for recording with a pen plotter or inkjet recording device include general paper such as high-quality paper, pound paper, and writing paper, and coated paper such as art paper and cast coated paper. Can be mentioned.

However, in recent years, with the development of recording devices such as inkjet recording devices and pen plotters, sufficient recording characteristics have not been obtained with the above-mentioned conventional recording materials.

In other words, because high-speed recording and multicolor recording are performed that are incomparable to conventional recording materials, conventional recording materials have poor absorption of recording liquid, color development when multiple recording liquids are attached to the same location,
The color quality, etc. has not reached a satisfactory level.

In order to solve these problems, coated papers such as inkjet paper having a porous ink absorbing layer on the surface of the base material have been devised.

For example, JP-A-58-136480 describes an inkjet recording medium in which a support is provided with an ink-receiving layer mainly composed of a pigment having a refractive index of 1.58 or less.

Unlike conventional recording media, this recording medium allows the recorded image to be observed from the support side, and the ink-receiving layer adjacent to the support is made mainly of pigments with a refractive index of 1.58 or less. By constructing the color r1 current,
The objective is to obtain recorded images with good color density.

However, although this recording medium has relatively good ink absorption, since the pigment layer is used as an ink absorption and retention layer, it has the disadvantage that it is inferior in ink fixability, resolution, color properties, and optical density of recorded images. .

In addition, recently, as the speed and quality of recording using inkjet recording devices, pen plotters, etc. has increased,
Recording materials are also required to have dramatic recording performance.

In other words, there is a need for a recording material that is significantly superior to conventional recording materials in all aspects of recording performance, such as absorption of the recording liquid, color development of the recording agent, quality of the recorded image, resolution, color, density of the recorded image, and gloss. It's here.

[Problems to be Solved by the Invention] However, the current situation is that a recording material that simultaneously satisfies all of these recording characteristics has not yet been obtained.

Therefore, an object of the present invention is to provide a recording material that has excellent ink absorption and fixing properties.

Another object of the present invention is to provide a recording material from which recorded images with high optical density and excellent color properties, color development, and resolution can be obtained.

Furthermore, the object of the present invention is to have a glossy surface, water resistance,
The object of the present invention is to provide a recording material from which recorded images with excellent durability such as light resistance can be obtained.

[Means for solving problems] The above object is achieved by the present invention as follows.

That is, the present invention provides a coating comprising a porous ink-permeable layer and a non-porous ink-retaining layer, and the ink-permeable layer has a porosity in the range of 0.2 to 0.75. It is a recording material.

[Function] The first feature of the recording material of the present invention is that unlike conventional recording materials in which the image recording surface and the viewing surface are the same, the image recording surface and the viewing surface are front and back. The second reason is that the porosity of the ink permeable layer is in the range of 0.2 to 0.75.

That is, in the recording material of the present invention, recording is performed using a recording liquid on the ink permeable layer on the recording side, and the recorded image is observed from the ink retaining layer (or base material) on the observation side.

Therefore, the ink permeable layer has liquid permeability, and its surface has (C
The ink retaining layer has the function of quickly absorbing and permeating the recording liquid that has landed on the layer, and the ink retaining layer has the function of absorbing and retaining the recording liquid or recording agent that has migrated from the ink permeable layer.

At this time, the ink permeable layer must have high affinity for the liquid medium in the recording liquid, and at the same time, the recording agent (dye,
For colorants such as pigments and materials with color-forming properties,
On the contrary, affinity must be low.

Therefore, the ink permeable layer wets the recording liquid medium.
It has properties such as penetration and diffusion, and has adsorption and adsorption properties for recording media.
It must be constructed by selecting a material that does not have characteristics such as penetration and reaction.

If the ink permeable layer does not have properties such as wetting, permeation, and diffusion with respect to the recording liquid medium, when the recording liquid is applied to the surface of the ink permeable layer, it will quickly permeate inside the ink permeable layer. As a result, the absorbency of the recording liquid decreases.

Furthermore, the recording liquid remains retained in the ink permeable layer and does not reach the ink retaining layer, making it impossible to obtain a recorded image with excellent water resistance.

Furthermore, if the ink permeable layer has properties such as adsorption, penetration, and reaction with respect to the recording agent, the recording agent will remain on the surface or inside the ink permeable layer and will not reach the ink retaining layer. It becomes impossible to obtain a recorded image with high optical density and sufficient color properties.

On the other hand, the ink retaining layer is only temporarily an ink permeable layer.

Therefore, the ink retaining layer must have high affinity for the recording agent as well as for the recording liquid medium.

As a result of intensive research, the present inventors have found that in the recording material having the above-mentioned ink permeable layer and ink retention layer, the absorption and permeability of the recording liquid largely depend on the porosity of the ink permeable layer. In order to form high quality images with good ink absorption, the porosity of the ink permeable layer should be 0.2 to 0.
．． They discovered that it is necessary to have a range of 75, and came up with the present invention.

The porosity A in the present invention refers to a value expressed by A=(V2-Vl)/V2, where v2 is the apparent volume of the ink permeable layer and vl is the true volume.

Specifically, an ink permeable layer is formed on the surface of a substrate that does not absorb solvents, such as a glass plate or aluminum foil, and its apparent volume V2 is measured from the thickness and area. It can be calculated by measuring the true volume Vl of the ink-permeable layer using an active solvent (eg, benzene, ethanol, etc.).

In the present invention, the porosity of the ink permeable layer is 0.2 to 0.
．． The range is preferably 75, preferably 0.25 to 0.6.
The range is 9.

When the porosity is less than 0.2, the absorbency of the recording liquid decreases significantly, making it impossible to perform high-speed and high-quality recording; when the porosity is 0.75 or more, the absorbency of the recording liquid is good. However, the resolution of the formed image is significantly reduced and a sharp image cannot be provided.

Hereinafter, the present invention will be described in detail based on embodiments.

The recording material of the present invention includes a base material as a support, and absorbs substantially the recording liquid or recording agent formed on the support.
It is composed of an ink retaining layer that captures the ink, and an ink permeable layer formed on the ink retaining layer that directly receives the recording liquid but has liquid permeability that does not substantially leave the recording agent behind.

However, if the ink permeable layer or the ink retaining layer also functions as a base material, the base material is not necessarily required.

As the base material used in the present invention, any conventionally known base material can be used, such as polyester resin, diacetate resin, triacetate resin, polystyrene resin, polyethylene resin, polycarbonate resin, polymethacrylate resin, etc.
1. Plastic films, plates, and glass plates made of resins, cellophane, celluloid, polyvinyl chloride resin, polyimide resin, polysulfone resin, etc., can be mentioned.

As mentioned above, since the recording material of the present invention is to be observed from the side opposite to the recording surface, the base material needs to have light-transmitting properties.

In addition, the base material used may be subjected to any processing as long as it finally has translucency; for example,
It is possible to give the base material a desired pattern or luster (moderate gloss or silky texture).

Furthermore, by selecting a base material having water resistance, abrasion resistance, and blocking resistance, water resistance, abrasion resistance, and blocking resistance can be imparted to the image observation surface of the recording material.

The ink permeable layer constituting the recording material of the present invention needs to have liquid permeability.

In the present invention, liquid permeability means that the recording liquid can pass through quickly,
This is a property that substantially prevents the recording agent in the recording liquid from remaining in the ink permeable layer.

In the present invention, a preferable embodiment for improving liquid permeability is that cracks and communication holes are formed on the surface and inside of the ink permeable layer.
The aim is to create a porous structure containing microscopic particles (including micro-sized ones).

For example, when recording using water-based ink, the following aspects may be mentioned.

(1) An embodiment in which the layer is made up of non-staining particles and a binder and has cracks inside; (2) The layer is made porous by dispersing other materials in the coating and treating it with a solvent. (3) A mode in which the resin is decomposed into a mixed solvent, and the solvent with a high Buddha point acts as a poor solvent for the resin, making the inside of the layer porous; (4) A mode in which a foaming material is included during film formation. In this embodiment, the inside of the layer is porous.

The materials used at this time are selected to be non-wettable to water and the solvent in the ink, and non-stainable to the dye in the ink.

A preferred embodiment of the ink permeable layer according to the present invention that satisfies the above properties is, for example, an embodiment consisting of particles that are non-stainable to the recording material and a binder.

Examples of non-staining particles that satisfy the above properties include organic resin particles such as thermoplastic resins and thermosetting resins, such as polyethylene, polymethacrylate, elastomers, ethylene-vinyl acetate polymers, and styrene-acrylic copolymers. At least one of organic resin powders and emulsions such as polyester, polyacrylic, and polyvinyl ether may be used as desired.

Furthermore, the binder used has the function of binding the particles and/or the ink retaining layer, and, like the particles, must be non-adsorbent to the recording material. .

As a material preferable as a binder, any conventionally known material can be used as long as it has the above-mentioned function. For example,
Polyvinyl alcohol, acrylic resin, styrene-acrylic copolymer, ethylene-vinyl acetate polymer, starch, polyvinyl butyral, gelatin, casein, ionoboo, gum arabic, carboxymethyl cellulose,
One or more resins such as polyvinylpyrrolidone, polyacrylamide, phenol, melamine, epoxy, styrene-butadiene, rubber, urea, α-olefin, vinylurethane, polyurethane, nitrile rubber, and chloroprene may be used as desired.

Further, pigment particles can be added to the ink permeable layer to the extent that the ink permeability thereof is not hindered.

Furthermore, in order to improve the function as an ink permeable layer, various additives such as surfactants, penetrants, etc. may be added to the ink permeable layer as necessary.

In the present invention, the porosity of the ink permeable layer is controlled within the above range by adjusting the particle size of the particles, the mixing ratio of the particles and the binder, and the like.

The mixing ratio (weight ratio) of the particles and the binder is preferably in the range of particles/binder = 1/3 to 50/1, more preferably in the range of 3/1 to 20/1. .

If this mixing ratio is 1/3 or less, the cracks and communication pores in the ink permeable layer become small, and the recording liquid absorption effect decreases. Furthermore, if the mixing ratio is 5071 or more, the adhesion between the particles or between the particles and the ink retaining layer becomes insufficient, making it impossible to form an ink permeable layer.

The thickness of the ink permeable layer depends on the amount of charge of the recording liquid, but is preferably 1 to 200 gm, more preferably 5 to 1 gm.
00gm.

Next, the non-porous ink retaining layer that substantially captures the recording liquid or recording agent absorbs and captures the recording agent that has passed through the ink permeable layer, and substantially permanently retains the recording agent. Therefore, the ink retaining layer is required to have a stronger ability to absorb recording liquid than the ink permeable layer.

This is because if the absorption power of the ink retention layer is weaker than the absorption power of the ink transmission layer, the recording liquid applied to the surface of the ink transmission layer will pass through the ink transmission layer, and the leading edge of the recording liquid will pass through the ink transmission layer. When the recording liquid reaches the ink-retaining layer, the recording liquid stays in the ink-permeable layer, and at the interface between the ink-permeable layer and the ink-retaining layer, the recording liquid permeates and diffuses laterally within the ink-permeable layer. That will happen.

As a result, the resolution of the recorded image decreases, making it impossible to form a high-quality image.

Further, as described above, since the recorded image is observed from the side opposite to the recording surface, the ink retaining layer needs to be light-transmissive.

The ink retaining layer that satisfies the above requirements is preferably composed of a light-transparent resin that adsorbs the recording agent and/or a light-transparent resin that is soluble and swellable in the recording liquid.

For example, when an aqueous recording liquid containing an acid dye or a direct dye is used as a recording agent, the ink retaining layer has a cationic resin that has an adsorption property for the dye and/or a swellability for the aqueous recording liquid. It will be composed of a hydrophilic polymer.

As the above-mentioned polymer, for example, those listed below are preferably used.

(1) Block copolymers or graft copolymers having a hydrophilic segment and a hydrophobic segment in the molecule These block copolymers or graft copolymers are generally water-insoluble but hydrophilic. Hydrophilic segments of such polymers include, for example, carboxyl groups, sulfonic acid groups, hydroxyl groups, ether groups, acid amide groups, methylolated groups thereof, primary to tertiary amino groups, quaternary ammonium groups, etc. It is a segment in which two or more vinyl polymers having a hydrophilic group are polymerized. Examples of such hydrophilic polymers include (meth)acrylic acid,
Mono (meth)acrylate I or monomaleate of polyols such as maleic anhydride, vinyl sulfonic acid, sulfonated styrene, vinyl acetate, ethylene glycol, (meth)acrylic acid amide, their methylolated products, mono- or dialkylaminoethyl (meth) ) acrylates, quaternized products thereof, vinylpyrrolidone, vinylpyridine, and the like.

Hydrophobic polymer segments include olefins such as ethylene, propylene, and butylene, aromatic vinyl compounds such as styrene, methylstyrene, and vinylnaphthalene, halogenated olefins such as vinyl chloride, vinylidene chloride, and vinylidene fluoride, ( It is a polymer of two or more monomers such as meth)acrylic acid, crotonic acid, and various alcohol esters of low unsaturated carboxylic acids.

In addition, water-soluble polymers other than those mentioned above, such as albumin,
Gelatin, casein, starch, cationic starch, gum arabic, natural resins such as sodium alginate, polyvinyl alcohol, polyamide, polyacrylamide, polyvinylpyrrolidone, polyethyleneimine, polyvinylpyricillium halide, melamine resin, polyurethane, polyester, sodium polyacrylate It goes without saying that hydrophilic natural or synthetic polymers such as the above or hydrophobic natural or synthetic polymers modified to be water-insoluble can also be used as the hydrophilic polymer segment or the hydrophobic polymer segment.

(2) Crosslinked products of water-soluble polymers Various water-soluble polymers as mentioned above and below are cross-linked with a suitable cross-linking agent or radiation to the extent that they become water-insoluble without losing their hydrophilicity.

(3) Polymer complex A polymer complex is composed of two or more mutually different water-soluble to hydrophilic polymers that act on each other, and produces a mixture with properties different from any of the original polymers. For example, two or more types of polymers form some kind of strong bond due to interionic electrostatic force, hydrogen bonding, van der Waals force, partial transfer of charge, etc.

Although various kinds of polymer complexes can be used, a particularly preferred one in the present invention is a polymer complex consisting of a basic polymer and an acidic polymer.

Note that the material constituting the ink retaining layer is not particularly limited as long as it has the function of absorbing and trapping the recording liquid and can form a non-porous layer.

The thickness of the ink holding layer may be sufficient as long as it is sufficient to absorb and trap the recording liquid, and although it varies depending on the amount of recording liquid, it is preferably 1 to 5071 m, more preferably 3 to 20 g.
It is m.

As a method for forming an ink retaining layer and an ink permeable layer on a substrate, a coating solution is prepared by dissolving or dispersing it in the above-mentioned appropriate solvent, and the coating solution is coated by, for example, a roll coating method,
Rod bar coating method, spray coating method,
It is preferable to apply the coating onto a substrate by a known method such as an air knife coating method and then quickly dry it. A method such as laminating the sheet onto a base material may also be used.

However, when providing the ink retaining layer on the base material, it is necessary to ensure strong adhesion between the base material and the ink retaining layer and eliminate spaces.

If a space exists between the base material and the ink retaining layer, the surface of the recorded image will be subject to diffuse reflection, which will lower the substantial optical density of the image, which is not preferable.

Examples of means for forming an image using the recording material of the present invention include a fountain pen, a ballpoint pen, a felt-tip pen, and a pen plotter.
, ink mist, inkjet, various types of printing, and other recording devices and devices that use a recording liquid containing a recording agent.

Among these recording devices and recording devices, inkjet recording devices and pen plotters are preferred from the viewpoint of high-speed image recording.

The recording liquid for recording on the recording material of the present invention includes:
Conventionally known aqueous and/or pongee yarn recording liquids are preferred, and in order to quickly penetrate the ink permeable layer and be quickly absorbed and captured by the ink retaining layer, the recording liquid should have a viscosity of 1000c.
ps or less, preferably 100 cpS or less, preferably 50 cpS or less
It is necessary that it is less than cps.

However, in consideration of stability against fire, resistance to environmental contamination, etc., water-based recording liquids are preferred. As the recording agent contained in the recording liquid, any conventionally known coloring agents such as dyes and pigments and/or those having color-developing properties can be used.

For example, as the recording agent used in inkjet recording, water-soluble dyes such as direct dyes, acid dyes, basic dyes, reactive dyes, and food colorings are preferred.

Formation of an image using the recording material of the present invention is carried out by recording an image with a recording liquid on the ink-permeable layer side of the recording material using a recording device capable of printing mirror characters (reverse characters). .

[Examples] The present invention will be specifically described below based on Examples. still,
In the text, parts are by weight unless otherwise specified.

EXAMPLES AND COMPARATIVE EXAMPLES A polyethylene terephthalate film (thickness: loopm, manufactured by Toshi) was used as a translucent base material, and the following composition A was coated on the base material using a bar coater so that the dry film thickness was 81 Lm. It was coated by the method and dried in a drying oven at 120°C for 5 minutes.

Further, each of the compositions B to F described above was coated on the chewing material A using a bar coater method to a dry film thickness of 25 JLm, and dried in a drying oven for 800 minutes to obtain a recording material. B-
I created F.

Composition B rate 0.18) Composition C rate 0.2) Composition D rate 0.54) Composition E rate 0.69) Composition F rate 0.75) All of the five types of recording materials B to F thus obtained were white and opaque.

For these recording materials, we use a recording device with an on-demand inkjet recording head that uses the following four types of ink to generate bubbles with a heat-generating resistor and uses the pressure to eject recording liquid. Inkjet recording was performed in solid color.

Table 1 shows the compositions of the four types of recording liquids used.

Table 1 Yellow Ink C, 1, Direct Yellow 86 2 parts N-methyl-2-pyrrolidone 10 parts diethylene glycol 20 parts polyethylene glycol #200 15 parts water
55 parts magenta ink C, 1, acid red 35
2parts N-methyl-2-pyrrolidone
10 parts diethylene gelcol 20 parts polyethylene glycol #200
15 parts water
55 parts cyan ink C, 1, direct blue 86
2parts N-methyl-2-pyrrolidone
10 parts diethylene glycol 20 parts polyethylene glycol #200
15 parts water
55 parts black ink C, 1, food black 2
2parts N-methyl-2-pyrrolidone
10 parts diethylene glycol
20 parts polyethylene glycol #200
15 parts water
55 copies of the thus obtained recorded material was tested and evaluated in accordance with the following method to determine whether it was sufficiently suitable for the purpose of the present invention.

1) The porosity was calculated as described in the specifications.

2) Ink absorbency was determined by measuring the time it took for the recorded matter to dry and fix sufficiently without adhering to the recorded area even when touched with a finger by leaving the recorded matter at room temperature after inkjet recording.

3) Image optical density (0, D) is determined by Macbeth densitometer TR-
524, image observation surface A for the black ink recording area.
was measured from recording surface B.

4) The shape of the dots was determined by observing the printed dots with a stereomicroscope.
Irregular shapes were marked as ×.

5) The degree of bleeding was measured by measuring the printed dots using a stereomicroscope, and was expressed as how many times larger the printed dots were than the ink droplets.

6) Color vividness was determined by visually comparing the color vividness of the inkjet recorded images, and ranking the best one as 0 and the worst as ×, as O, O1Δ, and ×.

Table 2 [Effects of the Invention] As described above, in the recording material of the present invention, the recording surface and the observation surface are in a front-back relationship, that is, recording is performed from the ink-permeable layer side, and recording is performed from the base material side (or the ink-retaining layer side). By observing the image from the side), it is possible to provide a clear recorded image with extremely high optical density, which was previously impossible when recording on a porous sheet such as paper.

Further, in the recording material of the present invention, by setting the porosity of the ink permeable layer serving as the recording surface to a range of 0.2 to 0.75,
It becomes possible to increase the resolution while maintaining the absorbency of the recording liquid.

Furthermore, by using a translucent base material as a support,
Gloss, water resistance, weather resistance, and abrasion resistance can be imparted to recorded images.

The recording material of the present invention is significantly superior in terms of optical density and operability during image creation, as compared to the conventional method of laminating a transparent film on the surface of a recorded image.

Claims (5)

[Claims] (1) It has a porous ink-permeable layer and a non-porous ink-retaining layer, and the ink-permeable layer has a porosity of 0.2 to 0.75.
A recording material characterized by being in the range of. (2) The recording material according to claim 1, wherein the ink retaining layer and the ink permeable layer are laminated on a base material. (3) The recording material according to claim 2, wherein the base material is translucent. (4) The recording material according to claim 1, wherein the ink permeable layer is mainly composed of particles that are non-stainable to the recording agent and a binder. (5) Claim 1, wherein the ink retaining layer is mainly composed of a cationic resin and/or a hydrophilic polymer.
Recording material described in section.