JPS62170382A - Recorded material - Google Patents

Abstract

PURPOSE:To enable a superior ink absorption in recording which is compatible with a superior transparency and film strength etc. after recording, by a method wherein a porous ink absorbing layer having a void capacity of a specific range is formed on a transparent substrate. CONSTITUTION:In a recorded material for an ink jet recording, a void capacity of an ink absorbing layer is regulated to be in the range of 0.1-100mul/cm<2>, which enables a superior ink absorption in recording which is compatible with a superior transparent treatment conducted after recording. Furthermore, if the void ratio of the porous ink absorbing layer is regulated to be in the range of 0.20-0.75, it is made possible that a superior ink absorption is accomplished without uselessly increasing the film thickness of the ink absorbing layer and the ink absorbing layer is prevented from reduction in the flexibility and occurrence of cracks caused by a transparent treatment, thus a layer of high transparency can be uniformly formed by a short-time application of a transparent treatment with heat. Additionally, a void ratio controlled to be in a specified range ensures a high film strength.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is suitable for use in recording materials, particularly in inkjet recording methods, and has excellent ink absorbency, water resistance, blocking resistance, etc. The latter part relates to a recording material for inkjet recording that provides recorded images with excellent transparency, sharpness of recorded images, water resistance, storage stability, etc.

(Prior Art) Inkjet recording methods include various ink (recording liquid) ejection methods, such as an electrostatic suction method, a method that applies mechanical vibration or displacement to the ink using a piezoelectric element, and a method that heats the ink to foam it. This method utilizes the pressure to generate and fly ink droplets, and some or all of them adhere to a recording material such as paper to perform recording, but it generates little noise and It is attracting attention as a recording method that allows high-speed printing and multicolor printing.

Ink for inkjet recording is mainly composed of water for safety and recording characteristics, and polyhydric alcohol is added to prevent nozzle clogging and improve ejection stability. It is often done.

Conventionally, the recording material used in this inkjet recording method is a recording material made of a base material called ordinary paper or inkjet recording paper with a porous ink absorption layer provided on it. .

However, as the performance of inkjet recording apparatuses increases and becomes more widespread, such as faster recording speeds and multicolor recording, more advanced and wide-ranging properties are being required of recording materials.

In other words, the recording material for inkjet recording to obtain high-resolution, high-quality recorded images must (1) be able to receive ink as quickly as possible on the recording material, and (2) have overlapping ink dots. (3) Ink droplets do not spread on the recording material and the diameter of the ink dot does not become larger than necessary, (4) ) The shape of the ink dot should be close to a perfect circle and its circumference should be smooth; (5) The OD (optical density) of the ink dot should be high and the periphery of the dot should not be blurred. There is.

Furthermore, in order to obtain high-resolution recorded image quality comparable to color photography using a multicolor inkjet recording method, in addition to the above-mentioned required performance, (6) the coloring components of the ink must have excellent color development; 7) The ink fixability is particularly excellent since the same number of droplets as the number of ink colors may adhere to the same location in an overlapping manner.

(8) The surface is glossy; (9) #Excellent aqueous properties.

etc. are required in a weighted manner.

In addition, images recorded by the inkjet recording method have traditionally been used exclusively for surface image observation, but as the performance of inkjet recording devices has improved and become more widespread, recording materials suitable for purposes other than surface image observation have become available. is becoming required.

Applications of recording materials other than surface image observation include those used to project recorded images onto a screen, etc. using optical equipment such as slides and OHP (overhead projectors), and observe those images; Examples include color separation plates used to create positive plates for color printing, and CMF (color mosaic filters) used in color displays such as liquid crystals.

When a recording material is used for surface image observation, the diffused light of the recorded image is mainly observed, whereas for recording materials used in these applications, the problem is mainly the transmitted light of the recorded image. Become. Therefore, it is required to have excellent light transmittance, especially linear light transmittance, in addition to the above-mentioned performance requirements of the general recording material for inkjet recording.

Conventionally, as the above-mentioned translucent recording material, since the ink used is a water-based ink, it is known that an ink absorbing layer made of a water-soluble to hydrophilic polymer is provided on a transparent base layer. However, such an ink absorbing layer has problems such as surface adhesion and blocking under high humidity conditions, and its ink absorbing properties are not always satisfactory.

It is clear that the ink absorbency of the ink absorbing layer can be improved by making the ink absorbing layer porous, but such a method cannot be used because if the ink absorbing layer is made porous, it loses its transparency as a recording material. In contrast, a porous ink absorption layer is provided on the transparent substrate to maintain sufficient ink absorption during recording, and after recording, the entire recorded ink absorption layer is made transparent by heat treatment. Attempts have also been made to do so (see, for example, Japanese Patent Laid-Open No. 59-178288 and Japanese Patent Laid-Open No. 59-178290).

(Problems to be Solved by the Invention) Although the recording material subjected to the above-mentioned transparent treatment after recording shows improved performance to some extent, it is not necessarily satisfactory.

In other words, in these known recording materials, the correlation between various required performances such as the ink absorbency of the formed ink absorbing layer, the strength of the ink absorbing layer, and the transparency by heat treatment is not clear, and some When trying to improve performance, other problems arose, such as a decline in other performances. For example, when the thickness of the ink absorbing layer is increased in order to improve ink absorbency, various problems arise, such as cracks appearing in the ink absorbing layer after heat treatment and severe powder falling off.

Therefore, the recording material that is subjected to the transparent treatment after the above Q shows excellent ink absorption, water resistance, blocking resistance, etc. during recording, and high transparency can be achieved by heat treatment after recording, and excellent There is a need for a recording material that provides recorded images with water resistance, clarity, and storage stability.

(Means for Solving the Problems) That is, the present invention heat-treats a recording material having a transparent base material and a porous ink absorbing layer provided on the base material after recording. In the recording material to be made transparent, the void volume of the porous ink absorbing layer is 0.1 to 0.1.
The recording material is characterized in that it has a cross-sectional area of 100 g/cm''.

In the present invention, the "void volume (A)" of the porous ink absorbing layer means that the apparent volume per unit area of the porous ink absorbing layer is v2, and the void volume of the porous ink absorbing layer is B. Then, A=BXv2. Furthermore, the "porosity CB)" referred to in the present invention is the value expressed by B=(V2-Vl')/V2, where the apparent volume of the porous ink absorbing layer is V2 and the true volume Vl. say.

Specifically, a porous ink absorbing layer is formed on the surface of a substrate that does not absorb solvents, such as a glass plate or aluminum foil.
Measure the apparent volume v2 from the thickness and area, and then measure the true volume Vl of the porous ink absorbing layer using a solvent inert to the porous ink absorbing layer (e.g. benzene, ethanol, etc.) It can be calculated by

As a result of intensive research to solve the above-mentioned drawbacks of the prior art, the inventors of the present invention discovered that in a recording material that is subjected to a transparent treatment after recording, the pore volume of the porous ink absorbing layer formed on the transparent substrate is Ink absorbency is the most important factor for transparency after recording, and by setting the void volume within a certain range, that is, 0.1 to 100 gJl/crn', excellent recording performance can be achieved. The present invention was completed based on the finding that it is possible to achieve both excellent ink absorption, excellent transparency after recording, and excellent film strength.

As described above, the recording material of the present invention basically consists of a transparent base material as a support and a porous ink absorbing layer provided thereon that can be made transparent by heat treatment.

The recording material used in the present invention as described above is generally obtained by forming a porous ink absorbing layer on a transparent base material, and suitable examples of such a transparent base material include Examples include polyester resins, diacetate resins, triacetate resins, polyolefin resins such as polyethylene and polypropylene, polystyrene resins, acrylic resins, polycarbonate resins, polysulfone resins, polyvinyl chloride resins, and polyimide resins. Examples include films or plates of resin, cellophane (trademark), celluloid (trademark), and glass plates. The thickness of such a transparent base material is generally about 10 to 5,000 μm.

The ink-absorbing layer formed on the transparent substrate as described above has excellent ink-absorbing properties when recording with water-based ink,
It is characterized by being made transparent by heat treatment after recording.

Such an ink absorbing layer is obtained by forming a porous layer from a thermoplastic resin. A method for forming such a porous ink absorption layer is to form a layer on a transparent substrate from a thermoplastic resin solution containing fine particles that can be eluted with a solvent, and then to elute only the fine particles in this layer. A method of forming a layer consisting of a binder and thermoplastic resin particles on a transparent substrate, or a method of creating a solution of a thermoplastic resin using a water-soluble organic solvent such as dimethylformamide. , such as a method of coating this on a transparent substrate and treating it with a poor solvent such as water to extract the water-soluble organic solvent to form a porous layer.
Any conventionally known method for forming a porous layer can be used in the present invention.

A particularly preferred method in the present invention is a method of forming a layer containing thermoplastic resin particles, and this method first forms an anchor coat layer on a transparent base layer using, for example, NBR latex, SBR latex, polyethyleneimine, styrene-malein, etc. A coating solution containing an acid copolymer or the like is applied by a known method, and while this layer is sticky, it can be coated with, for example, acrylic resin, styrene-acrylic acid copolymer, polyolefin resin, ethylene-propylene copolymer. A method of spraying and drying thermoplastic resin particles (plastic pigments) such as coalescence, ethylene-vinyl acetate copolymer, polyvinyl ether, polyester, polyamide, etc. Furthermore, a method of dispersing the above-mentioned plastic pigments in a binder polymer solution. This is then coated onto a transparent substrate by a known method and dried.

Binder polymers useful for forming the ink absorbing layer include, for example, albumin, gelatin, casein, starch, cationic starch, gum arabic, natural resins such as sodium alginate, carboxymethylcellulose, hydroxyethylcellulose, polyamide, polyacrylamide, polyethyleneimine, Polyvinylpyrrolidone, quaternized polyvinylpyrrolidone, polyvinylbilicylium halide, melamine resin, phenolic resin, alkyd resin,
Examples include synthetic resins such as polyurethane, polyvinyl alcohol, ion-modified polyvinyl alcohol, polyester, and sodium polyacrylate.

In addition to the water-soluble to hydrophilic polymers mentioned above, acrylic acid ester resins, polyvinyl acetate resins, polyvinyl butyral resins, ethylenethyl resins, polyolefin resins, polystyrene resins, ionomer resins, polyvinyl ether resins, etc. Thermoplastic resins such as resins, polyester resins, polyamide resins, polyurethane resins, butadiene rubber, acrylonitrile butadiene rubber, etc. can be used, and these resins can be used either in the form of organic solvent solutions or aqueous emulsions.

Particularly preferable fillers to be included in the ink absorption layer include particles of thermoplastic resin that becomes transparent when heated, such as plastic pigments such as polystyrene, polyethylene, polyvinyl chloride, and polymethyl methacrylate. is used.

These particles have a particle size of about 0.1 to 100 JLm, preferably about 0.2 to 50 JLm, and the amount added is determined so that the plastic pigment/polymer binder ( weight ratio)=3/1~2
0/1, more preferably 5/1 to 15/l.

In addition to the above ingredients, the ink absorption layer also contains a dispersant,
Various additives such as fluorescent dyes, pH regulators, antifoaming agents, lubricants, preservatives, surfactants, and penetrants may be optionally blended.

One method for forming a porous ink absorbing layer from such materials is to dissolve or disperse a mixture of the above-mentioned polymer and plastic pigment, containing appropriate additives as necessary, in an appropriate solvent and apply the mixture. Prepare the liquid,
Preferably, the coating solution is applied onto a transparent substrate by a known method such as a roll coating method, a rod bar coating method, a spray coating method, an air knife coating method, etc., and then quickly dried. Other methods may be used, such as hot-melt coating the material or forming a single porous ink-absorbing layer sheet from the above materials, and then laminating the sheet to the transparent substrate.

The ink absorbing layer formed as described above is porous and exhibits excellent ink absorbing properties due to its porosity.The ink absorbing properties of the ink absorbing layer are determined by its pore volume. Change. That is, as the void volume increases, the amount of ink absorption increases, and on the other hand, as the void volume decreases, the amount of ink absorption decreases. The void volume of such an ink absorption layer can be freely changed depending on the type, particle size, shape, amount used, and thickness of the ink absorption layer to be formed of the plastic pigment and binder used. However, according to detailed research by the present inventor, the void volume of the ink absorption layer is 0.17.
If the value is less than z cm/cm'', sufficient ink absorbency cannot be obtained even if the selection or thickness of the material forming the ink absorbing layer is changed, and the void volume of the ink absorbing layer is
/crn', although the ink absorbency is good, it becomes difficult to form the ink absorbing layer itself.
The most important thing is that it has been found that the transparency treatment performed after recording makes it impossible to easily form a highly transparent ink absorbing layer that is sufficiently strong and does not shed powder.

As mentioned above, the void volume of the ink absorption layer is set to 0.1 to 100.
By adjusting the ILi/cm' range, it is possible to achieve both excellent ink absorption during recording and excellent transparency treatment after recording.

Furthermore, in the present invention, by adjusting the porosity of the porous ink absorbing layer as described above to a range of 0.20 to 0.75, excellent results can be obtained without unnecessarily increasing the thickness of the ink absorbing layer. Achieves ink absorbency, prevents a decrease in flexibility and cracking of the ink absorbing layer due to transparent treatment, and can quickly and uniformly form a layer with high transparency through heat treatment. I can do it.

The recording material of the present invention as described above is made transparent by heat treatment after recording, and high transparency is required when it is used as a manuscript for optical equipment such as OHP and contact printers. However, the porous recording material of the present invention is
This can fully meet such demands.

In the present invention, sufficient light transmittance means that the recording material desirably exhibits a linear transmittance of 10% or more.

If the in-line transmittance is 2% or more, it is possible to project the recorded image onto a screen and observe it using an OHP, and furthermore, in order to clearly observe the details of the recorded image,
It is desirable that the in-line transmittance is 10% or more.

The linear transmittance T (%) here refers to the incident perpendicular to the sample, transmitted through the sample, and at least 8
The spectral transmittance of the straight light that passes through the light-receiving side slit on the extension line of the incident optical path separated by more than cm and is received by the detector is measured using, for example, the 323-type Hitachi self-recording spectrophotometer (newly manufactured by Hitachi). The Y value of the tristimulus value of the color is determined from the measured spectral transmittance using a linear equation.

T=Y/Y, ) and opacity (
The white and black backings are placed on the back of the sample and the ratio is calculated. ), which evaluates translucency using diffused light.

Since the behavior of straight-line light is a problem with devices that use optical technology, it is important to evaluate the straight-line transmittance of the recording material when evaluating the translucency of the recording material to be used in these devices. Asking is especially important.

For example, when observing a projected image on an OHP, in order to obtain a clear and easy-to-see image with high contrast between recorded and non-recorded areas, the non-recorded areas in the projected image must be bright;
That is, the in-line transmittance of the recording material is required to be at a certain level or higher. In an OHP test chart test, in order to obtain an image suitable for the above purpose, it is necessary that the straight transmittance of the recording material is preferably 105 or more in order to obtain a brighter image. It is said that Therefore, a recording material suitable for this purpose must have an in-line transmittance of 10% or more.

When recording with water-based ink, the recording material of the present invention as described above exhibits excellent ink absorbency because its recording surface is porous, and the water-based ink dries in a short time after recording. Therefore, even if a part of the device or a hand touches the recorded image during or after recording, the hand or the like will not get dirty or the image will not be disturbed, and high-speed recording is possible. In addition, since it is porous, the ink absorption layer does not necessarily need to be formed from water-soluble to highly hydrophilic polymers, and can be formed freely from hydrophobic polymers with high water resistance, so it can be used under high humidity conditions. Even if water droplets adhere to it, the surface does not become sticky and exhibits high water resistance and blocking resistance.

In addition, when the ink absorbing layer is made transparent by heat treatment after recording, the pore volume, preferably the porosity, of the ink absorbing layer is controlled within a certain range as described above, so that the transparent treatment is easy and high transparency is achieved. , film strength, and flexibility, it is possible to provide a transparent recorded image with high transparency and excellent color properties, sharpness, and the like. Such a recorded image exhibits high water resistance and light resistance because the water-soluble dye forming the image is sufficiently contained in the ink absorption layer and only a small portion is exposed on the surface. It also shows excellent permanence.

Therefore, the recording material of the present invention is used for observation by projecting a recorded image onto a screen using an optical device such as a slide or OHP, a color separation plate for creating a positive plate for color printing, or a liquid crystal display. It is useful for CMF used in color displays, and has various aptitudes that are superior to conventional ones.

Hereinafter, the present invention will be explained in more detail by giving Examples, Reference Examples, and Usage Examples. Note that 1 part or % in the text is based on weight unless otherwise specified.

Examples 1 to 3 and Comparative Examples 1 to 3 A polyethylene terephthalate film (Lumirror Q-80, manufactured by Toshi) with a thickness of 1100 JL was used as a transparent base material, and a coating liquid with the following composition was applied to the surface by the barniter method. The porous recording material of the present invention and the recording material of the comparative example were prepared by coating the porous recording material by coating and drying at 80° C. for 10 minutes. The thickness (when dry), void volume, and porosity of the ink absorbing layer of each formed recording material are shown together with the coating liquid composition.

Styrene emulsion (LX303, solid content 45%
, manufactured by Nippon Zeon) 100 parts polyvinyl alcohol (PVA-117, manufactured by Kuraray, 10% aqueous solution)
30 parts Iu; 30 parts Lem Neglected supervision J; 0-9 p-1/ cm"! In the evening 0
, 30 2.

Thermoplastic elastomer emulsion (A-100, solid content 40%, manufactured by Mitsui Petrochemicals)
100 parts ethylene-vinyl acetate copolymer emulsion (V-100, solid content 40%, manufactured by Mitsui Petrochemicals) 10 parts sodium dioctyl sulfosuccinate (Perex 0T-P, active ingredient 70% manufactured by Kao)
0.03 parts u; 50ILm Neglected dust j; 1.85 gfL/ crn'empty' [rate,
0.37 Styrene resin latex (La2O2, solid content 45%,
100 parts polyvinyl alcohol (PVA-117, 10% aqueous solution, manufactured by Kuraray)
45 parts; 50 tiles m! 2-70 g l/cm' for negligence
0, 54 1゛・Thermoplastic elastomer emulsion (A-100, solid content 40%, manufactured by Mitsui Petrochemicals)
100 parts ethylene-vinyl acetate copolymer emulsion, y (V-100, solid content 40%, manufactured by Mitsui Petrochemicals) 200 parts sodium dioctyl sulfosuccinate (Perex 0T-P, active ingredient 70% manufactured by Kao)
0.03 part ■; 50 pLm empty'' amount, 0.65 l sentence/C go! 0.13 2 in the evening (same as Example 1) 2.5 pm! 0.0925JLfL/c to escape! 0 for rubbing,
37 Group 3 (same as Example 3) 11! ! 2,000 m! Mouse dust 1; l O8μft/cm'! 0 for the mouse,
54 Usage Examples For the recording materials of the above Examples and Comparative Examples, the following 4
Inkjet recording was carried out using a recording apparatus having an on-demand inkjet recording head that generates bubbles using a heat generating resistor and ejects ink using the pressure of the seed ink.

Kai El (composition) C, 1, Acid Yellow 23 2 parts diethylene glycol 15 parts water
85 parts L Shiel (composition) C, 1, Acid Red 92 2 parts diethylene glycol 15 parts water
, 85 copies! E!
(Composition) C, 1, Direct Blue 86 2 parts diethylene glycol 15 parts water
85 parts 1 ether (composition) C, 1, Direct Black 19 2 parts diethylene glycol 15 parts water
85 copies Each of the recorded images obtained above was heated at 140° C. to 160° C. for 1 to 5 minutes to obtain transparent recorded images.

Table 1 shows the evaluation results of the recording materials of Examples and Reference Examples. Incidentally, each evaluation item in Table 1 was measured according to the following method.

(1) The ink fixation time was measured by leaving the recording material after recording at room temperature and touching the recorded image with a finger, and measuring the time taken for the ink to dry and stop adhering to the finger.

(2) Linear transmittance is measured using a Hitachi self-recording spectrophotometer model 323 (manufactured by Hitachi, Ltd.), keeping the distance from the sample to the light-receiving side approximately 9 cm, and measuring the spectral transmittance as described above. It was calculated using the formula.

(3) OHP suitability was measured as a representative example of optical equipment, and the recorded image was projected onto a screen using OHP.
Judgment is made by visual observation. 0 indicates that the non-recorded area is bright, the recorded image has a high 00 (optical density), and a clear and easy-to-see projected image with high contrast is obtained, and 0 indicates that the non-recorded area is slightly dark and the recorded image is high. If the OD of the image is rather low and the line with pitch width 0.5 + o + n and thickness 0.25 + am cannot be clearly distinguished, Δ, the non-recorded area is quite dark, the OD of the recorded image is quite low, pitch width lam, thickness A case where the 0.3 mm line could not be clearly distinguished or a case where the non-recorded area and the recorded image could not be distinguished was rated x.

(4) The overall evaluation is 0, which has good ink absorption and fixing properties, excellent inkjet recording suitability, sufficient transparency, and suitability for optical equipment, and (0) which has sufficient recording suitability, but ink fixation time. Two types of evaluations were conducted: those having a long length and unsuitable as recording materials, and those lacking recording suitability and suitability for optical equipment (x).

(Leaving space below) -m4-1-'' and knee good JJL UUJL (Evaluation items) 123 123 echo otsuden'' mouth E concave 2 seconds within 1 second within 1 second 1 day 581
Direct-paddy-processing rate within seconds 60% 75%
60% 60% 65% 40%9 Once once once once ooo oo.

Claims (3)

[Claims] (1) In a recording material having a transparent base material and a porous ink absorbing layer provided on the base material, the recording material is made transparent by heat treatment after recording. The void volume of the ink absorbing layer is 0.1 to 100 μl/c
A recording material characterized in that the range is m^2. (2) The recording material according to claim (1), which is a recording material for inkjet recording. (3) The porosity of the porous ink absorption layer is 0.2 to 0.7
5. The recording material according to claim (1).