JPS6141588A - Recording material - Google Patents

Abstract

PURPOSE:To form a light pervious recording material for ink jet recording excellent in ink receptivity and imparting excellent sharpness to a recorded image, by making the water solubility of an ink holding layer larger than that of an ink pervious layer. CONSTITUTION:An ink holding layer is mainly formed of a hydrophilic material capable of receiving aqueous ink and forming a layer having water solubility larger than that of an ink pervious layer and obtained by applying a coating solution which is prepared by dissolving or dispersing a polymer alone or a polymer mixture in a proper solvent, to a substrate before rapdily drying the same. The ink pervious layer is the thin layer made of a natural or synthetic resin, which was provided on the ink holding layer, formed of a polymer relatively inferior to hydrophilicity as compared with the polymer material forming the ink holding layer and has function such that the ink small droplet adhered to the surface thereof is rapidly enlarged in its contact area to a degree generating no excessive overlapping with the other mutually adjacent small ink droplet and penetrated into the ink holding layer to promote the reception of ink.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a recording material suitably used in an inkjet recording method, and in particular has excellent ink receptivity and clarity of recorded images, and When it is a translucent recording material, it relates to a recording material that has excellent ink receptivity and translucency.

(Prior Art) The inkjet recording method uses various ink (recording liquid) ejection methods, such as an electrostatic suction method, a method that applies mechanical vibration or displacement to the recording liquid using a piezoelectric element, and a method that applies mechanical vibration or displacement to the recording liquid using a piezoelectric element. In this method, small droplets of ink are generated and made to fly by foaming and using the pressure of the foam, and some or all of these droplets adhere to a recording material such as paper to perform recording, but this method generates noise. It is attracting attention as a recording method that allows for high-speed printing and multicolor printing.

Inks for inkjet recording are mainly water-based in terms of safety and recording properties.
Polyvalent □alcohol or the like is often added to prevent nozzle clogging and improve ejection characteristics.

The recording material used in this inkjet recording method has conventionally been a recording material made of a base material called ordinary paper or inkjet recording paper provided with a porous ink absorbing layer. However, as the performance of inkjet recording apparatuses improves 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 medium for inkjet recording to obtain high-resolution, high-quality recorded images requires (1) the ink to be fixed on the recording material as quickly as possible, and (2) ink dots to overlap. (3) Even if the ink droplets deposited later do not flow into the dots deposited earlier, (3) Although the ink droplets will spread to some extent on the recording material,
(4) The shape of the ink dot should be close to a perfect circle and its circumference should be smooth. (5) The OD of the ink dot should be the same. It is necessary to satisfy basic requirements such as high optical density (optical density) and no blurring around the dots.

Furthermore, in order to obtain high-resolution recorded image quality comparable to color photography using multicolor inkjet recording, in addition to meeting the required recording performance, (6) the coloring components of the ink must have excellent color development. , (7) The same number of droplets as the number of ink colors are particularly good at the same location, (8) The surface is glossy, (9) The whiteness is high, etc. required.

In addition, images recorded by inkjet recording 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. Applications of recorded materials other than 0 surface image observation, which are becoming increasingly required, include projecting recorded images onto a screen, etc. using an optical device such as a slide or 0HP (overhead projector), and observing those images. , color separation plates for creating positive plates for color printing, and CMFs (color mosaic filters) used for 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.

(The problem that the invention is trying to solve) However,
The reality is that there is still no known cover forest that satisfies all of these performance requirements.

Furthermore, most conventional recording materials for surface image observation use a method in which a porous ink absorbing layer is provided on the surface, and a recording liquid is absorbed into the porous voids to fix the recording agent.

On the other hand, when the surface of the ink absorption layer is non-porous, non-volatile components such as polyhydric alcohols in the ink remain on the surface of the recording material for a long time after recording, and the drying and fixing time of the ink is long. However, there are disadvantages in that clothing may get dirty or the recorded image may be damaged if it comes into contact with the recorded image.

An object of the present invention is to provide a recording material for inkjet recording that is particularly excellent in ink receptivity and the clarity of recorded images.

Still another object of the present invention is to use an optical device such as a slide or an OHP to project a recorded image onto a screen for observation, a color separation plate when creating a positive plate for color printing, or a liquid crystal display. An object of the present invention is to provide a translucent recording material for inkjet recording that can be used for observation of transmitted light such as CMF used in color displays.

The above and other objects of the invention are achieved by the following invention.

(Disclosure of the Invention) That is, the present invention comprises an ink retaining layer and an ink permeable layer, and is characterized in that the ink retaining layer has a higher water solubility than the ink permeable layer. This is a recording material.

To explain the present invention in detail, the recording material of the present invention has an ink permeable layer having a specific property of water solubility lower than the water solubility of the ink retaining layer at -L of the ink retaining layer. The main feature of the present invention is to provide the following, and the object of the present invention is mainly achieved thereby.

The recording material of the present invention generally comprises a base material as a support, an ink retaining layer provided on the surface thereof, and an ink permeable layer provided on the ink retaining layer. For example, as a particularly preferred main aspect, ( 1) An embodiment in which the base material, the ink retaining layer, and the ink transmitting layer are all translucent, and the recording material as a whole is translucent; (2) At least one layer of the base material, the ink retaining layer, and the ink transmitting layer. Examples include an embodiment in which the recording material is opaque and the recording material as a whole is opaque.

In any of the above cases, the ink retaining layer may also have the function of a support.

To explain the invention in more detail using the above two preferred embodiments as representative examples, as the base material that can be used as a support in the present invention, any conventionally known base material such as transparent or opaque can be used. Examples of suitable transparent base materials include polyester resins, diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide ST resins, cellophane, celluloid, etc. Examples include films or plates and glass plates. Preferred examples of the opaque substrate include, for example, general paper, cloth, wood, metal plates, synthetic paper, and the like, as well as the above-mentioned transparent substrates treated to make them opaque by known means. The thickness of such a base material is about lθ to 200 gm.

preferable.

In the present invention, the ink retaining layer provided on the base material is
It is formed of a hydrophilic material that can mainly accept water-based ink and forms a layer with greater water solubility than the ink permeable layer described below. Preferred examples of such materials include albumin, Gelatin, casein, starch, cationic starch, gum arabic, natural resins such as sodium alginate, polyamide, polyacrylamide, polyvinylpyrrolidone, quaternized polyvinylpyrrolidone, polyethyleneimine, polyvinylpyricillium halide,
Synthetic resins such as melamine resin, polyurethane, carboxymethyl cellulose, polyvinyl alcohol, cation-modified polyvinyl alcohol, polyester, and sodium polyacrylate can be mentioned, and one or more of these materials can be used as desired. Furthermore, in order to reinforce the strength of the ink retaining layer and/or improve the adhesion with the base material, SBR latex, NBR latex, polyvinyl formal, polymethyl methacrylate, polyvinyl butyral, polyacrylonitrile, polyvinyl chloride may be added as necessary. , polyvinyl acetate, phenol resin, alkyd resin, etc. may be used in combination.

As a method for forming such an ink retaining layer, a coating solution is prepared by dissolving or dispersing the above-mentioned polymers alone or in a mixture in an appropriate solvent, and the coating solution is coated by, for example, a roll coating method, It is preferable to apply the coating onto the substrate by a known method such as the Rottbar coat ink method, air knife coating method, or spray coating method, and then dry it quickly as described above. A single ink-retaining layer is formed by a known method such as a method or a T-die method, and the ink-retaining layer is used so as to have the function of a support.
By a method of laminating the sheet on the base material, a method of hot melt coating the polymer material, etc.
An ink retaining layer may be formed on the base material.

The thickness of the ink retaining layer formed in this way may be within a range capable of retaining ink, and although it depends on the amount of ink to be recorded, it is not particularly limited as long as it is 0.1 ILm. Practically speaking, 0.5 to 30 ILm is suitable.

The ink permeable layer used in the present invention and which mainly characterizes the present invention is a thin layer made of natural or synthetic resin provided on the ink retaining layer formed as described above, and the ink permeable layer is a thin layer made of natural or synthetic resin provided on the ink retaining layer formed as described above. When a droplet is deposited, the contact area is rapidly expanded (e.g., within a few seconds) to the extent that the droplet does not overlap excessively with other adjacent droplets, and the droplet penetrates into the ink-retaining layer. It also has the function of promoting ink reception by the ink retaining layer.

The inventor of the present invention conducted extensive research in order to provide the ink retaining layer with a function similar to "double series," and unexpectedly found that a By forming a thin layer with water solubility, -1-
It was discovered that the function described above can be easily achieved. It was truly surprising that such a function could be achieved even with thin films of polymers that, for example, have no or little solubility in water.

"Solubility in water" as used in the present invention refers to the viscosity when a layer of a certain weight formed to a certain thickness is dissolved in water, Ps is the viscosity when the layer is completely dissolved, and the viscosity of water is Po. When the viscosity is P
This is a value expressed as the time (2%, T54) until s rises.

To measure water solubility, use an E-type viscometer, for example, and place 0.0075 g of water on the bottom of a sample cup.
The polymer was formed into a layer of constant thickness under the same conditions, dried, and then 1.51% pure water was added, immediately set in a viscometer, and the viscosity was measured at 1100 rpm. The time when this bonito wood is placed in a sample cup is defined as TO, and the change in viscosity is measured over time. When the viscosity M stops, the measurement ends. After measurement, the relationship between viscosity and time is shown, and 2%
This is done by finding the time T34.

In the present invention, Ey! l! Although the concentration of each layer component was 0.5% using a viscometer, it goes without saying that the solubility may be compared using other methods.

Regarding the water solubility determined as described above, it can be said that the smaller the value, the greater the water solubility of the polymer.

The ink permeable layer having the above functions is made of a polymer having relatively poor hydrophilicity with respect to the polymer material forming the ink retaining layer, so that the ink permeable layer has a hydrophilicity of 10 #Lm or less, preferably about 0
．． This was achieved by forming a thin film with a thickness of 1-5 gm. Polymeric materials useful in forming such thin layers include homopolymers or copolymers of vinyl acetate, acrylic esters, ethylene, vinyl chloride, and other vinyl monomers; In contrast to the ink-retaining layer, the ink-retaining layer is made of a polymer consisting of a monomer, a polymer such as vinylon, polyurethane, a cellulose derivative, a polyester, a polyamide, and the above-mentioned wood-philic polymer for forming an ink-retaining layer, either alone or in a mixture. It is preferable to select one having a lower hydrophilicity than that of the above.

Further, the selected polymer may be a solution in an organic solvent, but it is preferably used in the form of an emulsion in an aqueous medium, an organic solvent, or a fine dispersion in an aqueous medium.

When used as an organic solvent solution, it is preferable to use a relatively dilute solution or a concentration such that the formed layer falls within the above range.

The method for forming the ink permeable layer using the above materials may be the same as that for forming the ink retaining layer.

Although the recording material of the present invention having the above-mentioned basic structure has a water solubility of the ink permeable layer that is inferior to that of the ink retaining layer, the recording material of the present invention has the basic structure as described above. ,
It is surprising that the ink receptivity and ink fixing properties are significantly improved compared to conventional recording materials that do not have such an ink permeable layer. Although the theoretical basis for this is currently unknown, according to the inventor's mere imagination (the present invention is not limited by such mere imagination), the above-mentioned ink permeable layer is not necessarily continuous. There are countless microscopic gaps in the ink-permeable layer that allow water-based ink to penetrate into the ink-retaining layer, rather than a film, and the surface is irregular on a microscopic scale, resulting in small ink droplets adhering to the layer. It is considered that the ink absorption and fixing properties of the ink retaining layer are significantly promoted by rapidly diffusing on the surface and expanding their contact area. Furthermore, since the ink permeable layer of the recording material of the present invention is formed from a polymer having lower water solubility than the ink retaining layer, the ink adhering to the surface is
The ink does not remain in the ink-permeable layer, but quickly permeates through the ink-permeable layer and is retained and fixed in the ink-retaining layer, which has high water solubility. In addition, since the ink permeable layer has low water solubility, even in a high temperature and high humidity atmosphere, the ink that has been received will not leak to the surface and contaminate equipment, operators, or the surrounding area. The surface will not become sticky under high temperature and high humidity conditions.

The above is the basic configuration of the present invention. However, in an embodiment in which the recording material of the present invention is translucent, a translucent material is used as the base material, and when forming the ink retaining layer and the ink transmitting layer, , it is necessary to ensure that these layers do not impair translucency. However, filling with silica, clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, synthetic zeolite, alumina, zinc oxide, lithopone, satin white, etc., to the extent that the translucency is not impaired. Agents can also be dispersed in the ink-retaining layer.

In the present invention, sufficient light transmittance means that the recording material exhibits a linear light transmittance of at least 2%, and preferably a linear light transmittance of 10% or more.

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

The linear transmittance T (%) here means that the light enters the sample perpendicularly, passes through the sample, and leaves the sample at least 8
The spectral transmittance of the straight light that passes through the light-receiving side slit located at the extension line of the incident optical path that is further away from c■ and is received by the detector is measured using, for example, a 323-type Hitachi self-recording spectrophotometer (newly manufactured by Hitachi), etc. The Y value of the color tristimulus value is determined from the measured spectral transmittance using the following formula.

T=Y/Y, rate (install an integrating sphere behind the sample to determine the transmittance including diffused light), 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.

The problem with devices that use optical technology is the behavior of straight-line light, so when evaluating the light transmittance of the recording material to be used in those devices, it is important to check the straight-line transmittance of the recording material. It is particularly important to seek

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, it is necessary that the non-recorded areas of the projected image be bright, that is, the straight line transparency of the recording material. It is required that the light rate be at a certain level or higher. In a test using a test chart at 0I (P), in order to obtain an image suitable for the above purpose, the linear transmittance of the recording material should be 2% or more, and in order to obtain a clearer image, it is preferably 10%. or more, and more preferably 50% or more.Therefore, a recording material suitable for this purpose must have an in-line transmittance of 2% or more. .

Further, in an embodiment in which the recording material of the present invention is opaque, an opaque material may be used for at least one layer among the base material, the ink retaining layer, and the ink permeable layer.

The method of forming each layer used in this embodiment is the same as in the transparency embodiment described above.

In this opaque embodiment, when forming the ink retaining layer and the ink permeable layer, it is possible to use a large amount of the filler to the extent that film forming properties are not impaired, thereby further improving excellent ink receptivity and fixing properties. can.

The present invention has been explained above by illustrating typical aspects of the recording material of the present invention, but of course the recording material of the present invention is not limited to these aspects. Also, the ink retaining layer contains a dispersant, fluorescent dye, P
Various known additives such as H regulators, antifoaming agents, lubricants, preservatives, and surfactants can be included.

Note that the recording material of the present invention does not necessarily have to be colorless, and may be a colored recording material.

As explained above and as demonstrated in the Examples below, the recording material of the present invention as described above has significantly improved ink reception and fixation, and for example, in the case of monochrome as well as full color. When recording images, even if recording liquids of different colors adhere to the same cylinder in duplicate within a short period of time, there is no phenomenon of recording liquid flowing out or seeping out, and images with high resolution, clarity, and excellent color development can be obtained. It will be done. Furthermore, when using an optical device such as a slide or OHP to project a recorded image onto a screen, etc. for observation, attached ink droplets are more likely to interfere with other adjacent areas than with conventional recording materials. Since the images are enlarged and fixed to such an extent that they do not overlap excessively, the transmitted light becomes even more uniform, providing a projected image with excellent uniform density. Furthermore, it can be suitably applied to uses other than conventional surface image observation, such as a color separation plate when creating a positive plate for color printing, or a CMF used in a color display such as a liquid crystal.

Hereinafter, the method of the present invention will be explained in more detail according to Examples. Note that parts in the text are based on weight.

Example 1 A polyethylene terephthalate film (manufactured by Toshi) with a thickness of 100% was used as a translucent base material, and coating liquid A having the following composition was applied onto this film so that the film thickness after drying was 201 L.
Coated by bar coater method so that
It was dried for 0 minutes to form an ink retaining layer. Next, apply the following coating solution B onto the ink retaining layer until the dry film thickness is 3p.
m, dried at 60℃ for 15 minutes,
An ink permeable layer was formed to obtain a translucent recording material of the present invention.

Coating liquid A composition: polyvinylpyrrolidone, -90 (manufactured by GAF, water soluble) 15 parts water
85 parts Coating liquid B composition: Carboxymethylcellulose (Shichirogen BS, Dai-Kogyo Seiyaku Co., Ltd., water soluble) 2 parts water
98 parts The thus obtained recording material of the present invention was colorless and transparent.

Example 2 A recording material of the present invention was obtained in the same manner as in Example 1 except that art paper was used as the base material.

Example 3 A polyethylene terephthalate film (manufactured by Kijin Co., Ltd.) with a thickness of 100 JL was used, and coating solution A having the following composition was coated on this film using a bar coater method so that the film thickness after drying was 100 JL. The ink retaining layer was formed by drying at 80°C for 1 hour.Then, the following coating solution B was applied onto the ink retaining layer so that the dry film thickness was 51 parts m. It was dried at .degree. C. for 20 minutes to form an ink-permeable layer, and the ink-retaining layer and ink-permeable layer were both peeled off from the polyethylene terephthalate film to obtain a translucent recording material of the present invention.

Coating liquid A composition: Polyvinyl alcohol (PVA 420'y manufactured by Rare, water soluble) 10 parts water.
90 parts Coating liquid B Composition Niacrylic acid ester (Guikaratsuk 51235, water soluble) 5 parts Ethanol 95 parts Example 4 Art paper was used as a base material, and coating liquid A with the following composition was applied on this base material. The ink retaining layer was formed by coating with a bar coater method so that the film thickness after drying was 25 pLIm, and drying at 50° C. for 20 minutes. Next, the following coating liquid B was applied onto the ink retaining layer so that the dry film thickness was 2 JLm, and dried at 70° C. for 10 minutes to form an ink permeable layer. I got the material.

Composition of coating liquid: Water-soluble acrylic resin (Korgum HW-7, Showa Kobunshi, water-soluble) 20 parts fine powder silica (Syroid #244 Fuji Davison) 5 parts water
75 parts Coating liquid B composition: Polyvinyl acetate (Movinyl 303, manufactured by Hoechst, water soluble) 10 parts water
90
Comparative Examples 1 to 4 Comparative recording materials were prepared in the same manner as Examples 1 to 4, except that the polymers for forming the ink retaining layer and the ink permeable layer were reversed.

An on-demand inkjet recording head (on-demand type inkjet recording head that ejects ink using a piezoelectric vibrator) uses the following four types of ink on the recording materials of the above examples and comparative examples.
Discharge orifice diameter 65#Lm, piezo vibrator drive voltage 7
Inkjet recording was performed using a recording device having a voltage of 0 V and a frequency of 3 KHz.

Yellow ink (composition) C, 1, Direct Yellow 86 2 parts N-methyl-
2-pyrrolidone 10 parts diethylene glycol
20 parts polyethylene glycol #200 15 parts water 55
Part magenta ink (composition) C, 1, acid red 35 2 parts N-methyl-2-pyrrolidone 10 parts diethylene glycol
20 parts polyethylene glycol #200 15 parts water 55
Part cyan ink (composition) C, 1, Direct Blue 86 2 parts N-methyl-
2-pyrrolidone 10 parts diethylene glycol
20 parts Polyethylene glycol #200 15 parts Water 55 parts Black ink (composition) C, 1, Food Black 2 2 parts N-methyl-2-pyrrolidone 10 parts Diethylene glycol
20 parts polyethylene glycol #200 15 parts water 55
The evaluation results of the recording materials of the above examples and comparative examples were evaluated in the first part.
Shown in the table. Each evaluation item in Table 1 was measured according to the following method.

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

(2) The dot density was calculated using Sakura Microdensidometer PD by applying JISK7505 to the printed microdots.
The black dots were measured using M-5 (manufactured by Konishiroku Photo Industry).

(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 OD (optical density) of the recorded image is high, and a clear and easy-to-see projected image with high contrast is obtained, while the non-recorded area is slightly dark and the recorded image is 0. If the OD of the image is rather low and the lines with a pitch width of 0.5 cm and a thickness of 0.25 cm cannot be clearly distinguished, Δ is used, the non-recorded area is quite dark, the OD of the recorded image is quite low, and the pitch width is l. ■■, thickness 0.3■
A case in which the line (2) could not be clearly distinguished or a case in which the non-recorded area and the recorded image could not be distinguished was marked as "×".

(4) Straight line transmittance was measured using a 323-type Hitachi self-recording spectrophotometer (manufactured by Hitachi Seisakusho), keeping the distance from the sample to the light-receiving side at approximately 9 cm, and measuring the spectral transmittance as described above. (
1) It was calculated using the formula.

(Hereafter, the rest is white) 2 Self-view - 13 and 2

Claims (1)

[Claims] A recording material comprising an ink retaining layer and an ink permeable layer, wherein the ink retaining layer has a higher solubility in water than the ink permeable layer.