JPH01204783A - Recording material - Google Patents

Abstract

PURPOSE:To ensure excellent ink absorptivity, light resistance even in outdoor use and excellent water resistance such as bleeding preventive properties under high-humidity conditions, by specifying the quantity of a basic compound incorporated in an ink receiving layer. CONSTITUTION:An ink-receiving layer provided on a base comprising a polyester resin, an acrylic resin or the like is constituted mainly of a water-soluble or hydrophilic resin capable of receiving water-based inks, and the amount of a basic compound contained in the layer is not more than 0.5wt.%. Such a resin as above often contains a basic compound, e.g., sodium acetate, lithium acetate or potassium acetate mixed therein. In that case, the basic compound contained in the resin can be removed by sufficient purification of the resin or by producing the resin with sufficient care.

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 absorbency, light resistance, and bleeding prevention property under high humidity. The present invention relates to a recording material that provides a recorded image.

(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 uses 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 less noise. It is attracting attention as a recording method that allows high-speed printing and multicolor printing.

For inkjet recording, aqueous inks containing water as a main component are mainly used from the standpoint of safety and recording characteristics, and polyhydric alcohols are added to prevent nozzle clogging and improve ejection characteristics. in many cases.

Conventionally, the recording material used in this inkjet recording method is a recording material that is made by providing a porous ink absorbing layer on a base material called ordinary paper or inkjet recording paper, which is used for surface image observation. has been used. As a recording material for such inkjet recording, (1) the ink fixes to the recording material as quickly as possible, and even if different color ink dots are important, ink that adheres later will not adhere to the front. (2) Although the ink droplets will spread to some extent on the recording material,
(3) The shape of the ink dot should be close to a perfect circle and its circumference should be smooth. (4) The OD (optical density) of the ink dot should be high and the ink components should be It is necessary to satisfy various requirements such as excellent color development.

In addition, images recorded by inkjet recording methods 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, and color recording materials. Examples include color separation plates used to create positive plates for 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.

(The problem that the invention is trying to solve) However,
A recording material that satisfies all of these required performances has not yet been known.

For example, it is known that the ink-receiving layer is made porous to improve ink absorption, but the image obtained in this case lacks transparency and gloss, making it unsuitable for use in observing transmitted light. It is.

Furthermore, in order to form a transparent ink-receiving layer on a transparent substrate, water-soluble or hydrophilic resins are used to form the ink-receiving layer, but these ink-receiving layers have poor water resistance; Another problem is that the recorded images have poor light resistance. Furthermore, under high humidity conditions, there is a problem that the surface becomes sticky due to water absorption and the image is likely to smear.

In order to solve this problem, there is a method of applying a moisture-proof transparent coating to the recording surface after recording, but this method is complicated to operate.
Furthermore, even if a transparent coating is applied, it cannot be said to have sufficient light resistance and water resistance when used outdoors, for example, as a display.

On the other hand, as inkjet recorded images have come to be used for outdoor posters and backlit displays, conventional inkjet images cannot meet the harsh conditions of outdoor use, that is, have excellent light resistance. However, there is now a demand for inkjet images that do not have sticky surfaces or blur images even under high-temperature atmospheres.

Therefore, an object of the present invention is to provide a recording material suitable for use in inkjet recording methods, which has particularly excellent ink absorbency, light resistance even when used outdoors, and excellent water resistance such as smear prevention properties under high humidity. It is an object of the present invention to provide a recording material that provides a recorded image with a unique character.

(Disclosure of invention) The above objects are achieved by the present invention as described below.

That is, the present invention provides a recording material comprising at least a base material and an ink-receiving layer, wherein the amount of a basic compound contained in the ink-receiving layer is 0.5% by weight or less. It is a material.

(Function) By controlling the amount of the basic compound present in the ink-receiving layer to 0.5% by weight or less of the ink-receiving layer, the light resistance of the image recorded on the recording material is improved.

In addition, because the amount of basic compounds is small, the recorded dye bonds directly with the resin constituting the ink-receiving layer by ionic or Van der Waalska methods, which prevents the image from bleeding even under high humidity. Improves water resistance.

Furthermore, since the number of free ions in the ink-receiving layer is small, that is, the ionic strength is lowered, the permeability of aqueous inks with relatively high ionic strength is generally increased, and the ink absorption speed and absorbability are improved.

In a preferred embodiment, the presence of a cation-modified resin in the ink-receiving layer further improves the water resistance of the image, and furthermore, by crosslinking the ink-receiving layer, the water resistance of the ink-receiving layer itself is improved.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

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 base material can be used. Examples suitable for the transparent base material include polyester resin, diluted resin, etc. Examples include films or plates of acetate resins, triacetate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, celluloid, and glass plates. In addition, examples of preferable opaque substrates include general paper, cloth, wood, metal plates, synthetic paper, etc., as well as the above-mentioned transparent substrates treated to make them opaque by known means. It will be done.

Preferably, such substrates have a thickness in the range of about 10 to 200 μm.

In the present invention, the ink receiving layer provided on the base material is
It is mainly formed from a water-soluble or hydrophilic resin that can accept water-based ink, and preferred examples of such resin include albumin, gelatin, casein,
Starch, cationic starch, gum arabic, hydrophilic natural resins such as sodium alginate, polyvinyl alcohol,
Cationized polyvinyl alcohol, polyamide, polyacrylamide, polyvinylpyrrolidone, quaternized polyvinylpyrrolidone, poly(N-vinyl-3-methylpyrrolidone), polyvinylimidazole, polyallylamine, polyallylamine hydrochloride, polyethyleneimine, polyvinylpyricylium halide Water-soluble or hydrophilic synthetic resins such as , melamine resin, polyurethane, carboxymethyl cellulose, hydroxyethyl cellulose, cationized and droxyethyl cellulose, hydroxypropyl cellulose, polyester, and sodium polyacrylate,
One or more of these materials may be used as desired. or,
To improve the adhesion and water resistance of the formed ink-receiving layer,
In addition to the above water-soluble or hydrophilic resins, hydrophobic resins such as SBR latex, NBR latex, polyvinyl formal, polymethyl methacrylate, polyvinyl butyral, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, phenolic resin, and alkyd resin are also used. They can be used together as long as they do not interfere with the purpose of the invention.

In the present invention, when forming the ink-receiving layer from the above-mentioned materials, it is important that the amount of the basic compound in the formed ink-receiving layer is 0.5% by weight or less.

That is, the various resins mentioned above usually contain sodium acetate, lithium acetate, potassium acetate, sodium hydrogen carbonate, lithium hydrogen carbonate, potassium hydrogen carbonate, alkali metal hydroxides, alkali metal carbonates, ammonium compounds, aliphatic Basic compounds such as lower amines are often mixed in, and if these compounds are present in the ink receiving layer, the direct dyes and acid dyes used in the ink during recording will be adsorbed to the resin. It has been found that these salts combine with each other before being processed, reducing the light fastness of the image and causing the image to smear due to hygroscopic moisture in a high-humidity atmosphere.

The basic compounds in the resin can be removed by sufficiently rusting the resin, or by paying sufficient attention during resin production.

For example, the above-mentioned method for removing the basic compound includes: (1) a method that utilizes the difference in solubility between the resin and the basic compound in water, lower alcohols, or polar solvents;
For example, ethyl alcohol is suitable for removing sodium acetate mixed in hydroxyethyl cellulose. Sodium acetate is dissolved in alcohol, and the extracted ethyl alcohol solution is filtered through filter paper or the like to separate the sodium acetate dissolved in ethyl alcohol from hydroxyethyl cellulose.

Alternatively, a Soxhlet extractor may be used to easily form the resin into granules.

That is, sodium acetate can be efficiently extracted by constantly bringing fresh ethyl alcohol into contact with hydroxyethyl cellulose using the reflux of ethyl alcohol in the extractor.

(2) Furthermore, IIt by membrane separation represented by reverse osmosis membrane method
'H is also valid. For example, 1+'rm of polyvinyl alcohol can be performed by separating the polyvinyl alcohol aqueous solution and pure water with a reverse osmosis membrane and removing only the basic compound by the osmotic power of the basic compound.

Generally, reverse osmosis membranes such as acetyl cellulose membranes, cellophane membranes, and polyamide membranes are used for such membrane separation. As for the shape of these separation membranes, in addition to flat ones, laver-wrapped membranes, spiral membranes, tubular membranes, and extremely fine hollow fiber membranes can be used.

After reducing the concentration of the basic compound in the resin forming the ink receiving layer to 0.5% by weight or less by the method described above,
The recording material of the present invention can be obtained by forming an ink receiving layer.

Furthermore, in a preferred embodiment of the present invention, when a non-cationic resin is used among the resins mentioned above in forming the ink-receiving layer, part or all of the resin can be made into a cation-modified product. The water resistance of the image and bleeding can be more effectively prevented compared to acidic dyes having low properties.

Unlike the above-mentioned basic compounds, cation-modified resins are
Even when reacting with dyes or forming salts, these reactants or salts do not run out due to moisture absorption or cause bleeding. In the present invention, cationic modification refers to introducing a primary to tertiary amino group or a quaternary ammonium group into the resin.

The cationic modification of the resin can be carried out by using a reactive cationic compound during or after the production of the resin. For example, the reactive cationic compound includes: 2.3-epoxypropyltrimethylammonium chloride, 3.4 -Epoxybutyltrimethylammonium chloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride.

Vinyl compounds that can be used during resin polymerization include vinyloxyethyltrimethylammonium chloride, 2,3-dimethyl-1-vinylimidazolinium chloride, and trimethyl-(3-acrylamido-3,3-dimethylpropyl)ammonium. Chloride, trimethyl-(3
-methacrylamidopropyl)ammonium chloride, N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, N-(3-dimethylaminopropylmethacrylamide, N,N-dimethylaminopropyl (meth)acrylate, N, Quaternary ammonium salts (or their precursors,
That is, vinyl monomers containing (primary to tertiary amino groups), 0-lm- or p-aminostyrene or their monoalkyl or dialkyl derivatives or their quaternary ammonium salts, 0-5m- or p-vinylbenzyl Amines or their alkyl or dialkyl derivatives or their quaternary ammonium salts, N-(vinylbenzyl)pyrrolidone, N-(vinylbenzyl)piperidine, N-vinylpyrrolidone, α- or β-vinylpyridine, or their derivatives. Examples include other nitrogen-containing heterocyclic vinyl compounds such as quaternary ammonium salts, α- or β-piperidine or their quaternary ammonium salts, 2- or 4-vinylquinoline or their quaternary ammonium salts.

When using the above-mentioned cation-modified resins, it is preferable that these cationic groups exist in an amount of 1% by weight or more of the ink-receiving layer, and if the amount is less than 1% by weight, the dyeability of acidic dyes is insufficient.

In another preferred embodiment of the present invention, it is preferable that the formed ink-receiving layer is cross-linked with a cross-linking agent (water-resistant agent) to improve the water resistance of the ink-receiving layer itself. As the crosslinking agent, polyisocyanate compounds, epoxy compounds, dialdehyde compounds, N-methylol compounds, etc. are useful.

For example, examples of polyisocyanate compounds having two isocyanate groups include 1.2-diisocyanate ethane, 1,2-diisocyanate propane, tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, and hexane. Methylene-1
, 6-diisocyanate, nonamethylene-1,9-diisocyanate, decamethylene-1,10-diisocyanate, ω,ω'-dipropyl ether diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, hexa Hydrodiphenyl-4゜4'-diisocyanate, hexahydrodiphenyl ether-4,4'-diisocyanate, phenylene-1,4-diisocyanate, toluylene-2,6-diisocyanate, toluylene-2゜4-diisocyanate 1-methoxybenzene-2 ,4
-diisocyanate, 1-chlorophenylene diisocyanate, tetrachlorophenylene diisocyanate metaxylylene diisocyanate, paraxylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylsulfide-4,4'-diisocyanate, diphenylsulfone-4,4'- Diisocyanate, diphenyl ether-4,4'-diisocyanate, diphenyl ether-3,4'-diisocyanate,
diphenylketone-4,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,
5-diisocyanate, 2,4'-bisphenyl diisocyanate, 4,4'-bisphenyl diisocyanate, 3°3'-dimethoxy-4,4'-bisphenyl diisocyanate, anthraquinone-2,6-diisocyanate, triphenyl Examples include methane-4,4'-diisocyanate and azobenzene-4,4'-diisocyanate.

Examples of compounds containing three isocyanate groups include compounds represented by the following structural formulas (I) to (III) and derivatives of these compounds.

Further, examples of the polyfunctional aldehyde compound include glyoxal, succindialdehyde, glutardialdehyde, adipodialdehyde, piperine dialdehyde, spering dialdehyde, and sebacine dialdehyde. Further, examples of the N-methylol compound include methylolmelamine, butylated methylolmelamine, and the like.

The water resistance of the ink-receiving layer can be improved by cross-linking the ink-receiving layer with a cross-linking agent such as the one mentioned above.In order to provide sufficient water resistance, it depends on the type and molecular weight of the water-soluble or hydrophilic resin. The amount of crosslinking agent may vary, but numerically it is preferably 1% by weight or more of the water-soluble or hydrophilic resin.On the other hand, if the degree of crosslinking is too high, the ink absorbency of the ink receiving layer will decrease, so the amount of crosslinking agent is It is preferably 50% by weight or less.

As a method for forming an ink-receiving layer from the above-mentioned materials, a coating solution is prepared by dissolving or dispersing the above-mentioned resins alone or in a mixture in an appropriate solvent. It is preferable to apply Moeki Murakami by a known method such as a coating method, rod bar coating method, air knife coating method, or spray coating method, and then dry it immediately. A single ink-receiving layer is formed by a known method such as a method or a T-die method, and the ink-receiving layer is used so as to have the function of a support, or the sheet is laminated on the above-mentioned base material. The ink-receiving layer may be formed on the base material by a hot-melt coating method using the resin material described above.

The thickness of the ink-receiving layer formed in this way may be within a range that can hold the ink, and although it depends on the amount of ink to be recorded, it is in the range of 1 to 50 μm, more preferably 3 to 20 μm. be. If the thickness is less than 1 μm, the ink cannot be completely absorbed, resulting in poor fixing.
If it exceeds .mu.m, there will be a drawback that the drying time after coating will be longer when forming an ink receiving layer.

Furthermore, in a preferred embodiment of the present invention, an ink transport layer is formed on the above-mentioned ink receiving surface.

As described in JP-A No. 62-242577, this ink transport layer is a layer that does not substantially adsorb ink and dye, and is preferably a porous layer formed of resin particles and a binder, Ink absorption can be further improved, and images with excellent image quality, high optical density, light resistance, water resistance, etc. can be formed.

The present invention has been described above by exemplifying 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. In any embodiment, the ink-receiving layer contains a dispersant, a fluorescent dye, a pH
Various known additives such as 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.

(Examples) Hereinafter, the present invention will be explained in more detail by giving Examples, Comparative Examples, and Usage Examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

Example 1 Cationization and droxyethyl cellulose (manufactured by Lion,
reflux of ethyl alcohol using a Soxhlet extractor was repeated for a total of 3 hours, and then refluxed for 3 hours.
The cationized hydroxyethyl cellulose was filtered off through a 50-mesh wire mesh. The resulting purified cationized and droxyethyl cellulose contained 31% ethanol. This was dried in an oven at 60° C. for 30 minutes to obtain rusted cationized hydroxyethyl cellulose.

A 100 μm thick polyethylene terephthalate film (manufactured by [, C, 1) was used as a translucent base material, and 5 parts of the purified cationized cellulose and droxyethyl cellulose were added to 95 parts of pure water on this film. The dissolved solution was coated by a bar coater method so that the film thickness after drying was 6 μm, and dried at 80° C. for 20 minutes to obtain a translucent recording material of the present invention.

Example 2 Cationized polyvinyl alcohol (manufactured by Kuraray, trade name
A 2% aqueous solution of C Polymer+1 Knee 318-2A) was prepared. The above aqueous solution was purified using a reverse osmosis membrane system using an acetyl cellulose membrane manufactured by Daicel Chemical. Finally, water was distilled off using a vacuum evaporator.

A polyethylene terephthalate film (manufactured by Toshi) with a thickness of 75 μm was used as a translucent base material, and a coating solution with the following composition was applied onto this film using a reverse roll coater method, and the film thickness after drying was as follows: Dry crosslinking was carried out by heat treatment at 140° C. for 5 minutes to give a thickness of 6 μm.

Kokooka Sarasai 10 parts of purified cationized polyvinyl alcohol 0.2 parts of isobutylene-maleic anhydride copolymer ammonium salt Water-soluble methylolated melamine resin (manufactured by Sumitomo Chemical, trade name Sumimaru M-30)
1. Solid content 77%) 0.4 parts Pure water 100 parts Furthermore, a coating liquid having the following composition was applied onto the above ink receiving layer by a reverse roll coater method so that the film thickness after drying was 35 μm, It was dried by heat treatment at 140° C. for 5 minutes to obtain a recording material of the present invention.

Koko Hakisarajo Urea Powder (manufactured by Nippon Kasei, product name: organic filler)
10 parts polyvinyl butyral resin (manufactured by Block Chemical Co., Ltd., trade name Kosurek 0H-3)
4-part surfactant (manufactured by Kao, product name
Perex 0T-P) 0.
3 parts Fluorescent brightener (manufactured by Ciba Geigy, trade name Uvitex NFW liq) 0, 0 3 parts Ethyl cellosolve 150 parts Example 3 Sodium polyacrylate (manufactured by Hiki Pure Chemical Industries, Ltd., trade name Julimar A (Nee 1ONP)) 5 % aqueous solution was prepared and purified using a reverse osmosis membrane system (acetylcellulose@) manufactured by Daicel Chemical.Finally, water was distilled off using a vacuum evaporator.

Using Cannon Paper NP DRY as the base material, -
A lθ% pure aqueous solution of the above sodium polyacrylate was coated on this base material by a bar coater method so that the film thickness after drying would be 12 μm, and then dried by heat treatment at 140° C. for 6 minutes to produce the recording material of the present invention. I got it.

Comparative Example 1 A recording material of a comparative example was obtained by performing the same operations as in Example 1 except that cationization and droxyethylcellulose were not purified.

Comparative Example 2 A recording material of a comparative example was obtained by performing the same operations as in Example 2 except that cationized polyvinyl alcohol was not produced.

Comparative Example 3 A recording material of a comparative example was obtained by performing the same operations as in Example 3 except that sodium polyacrylate was not washed.

Usage example: An on-demand inkjet recording head (discharge orifice diameter: 60 mm) that discharges ink using a piezo vibrator using the following four types of ink on the recording material described above.
μm, piezo vibrator drive voltage 65V, frequency 2KI-1
Inkjet recording was carried out using a recording apparatus having the following.

Yellow ink c, r, acid yellow 23 2 parts diethylene glycol 15 parts polyethylene glycol #2G0 10 parts water
75 parts red ink (:, 1. Acid Red 37 2 parts diethylene glycol 15 parts polyethylene glycol @200 10 parts water
75 parts Blue Ink C, 1, Direct Blue 86 2 parts diethylene glycol 15 parts polyethylene glycol @200 10 parts water
75 parts black ink (:, 1. Direct Black 19 2 parts diethylene glycol 15 parts polyethylene glycol $200 10 parts water
75 copies The recording characteristics of the recording material of the present invention and the image characteristics of the recorded print were evaluated,
The evaluation results are shown in Table 1 below. 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) Light resistance is Atlas Fade Meter C1-35
It was measured by the percentage of the initial OD and the OD2.0 after 200 hours of irradiation, and the average value of the four color inks was used.

(3) To prevent bleeding under high humidity, record images printed solidly with red ink using the recording device at 35°C/85%R.
The solid print width before storage was set to 20, and the solid print width was measured as a percentage of the increment (12ooJ!o) of the solid print width after storage for 200 hours.

11200”’110 Bleeding % = -X 100 IL.

(Leaving space below) Tsu-J 1-One salt u1 workmanship AAB ヱλ之5时朋(minutes) 20.5 or less 21 light (%)
30 36 28 Takaguri”] 3 Kura (%) 2.5 2 2.7 e thing
AAB I2F” 5J Terado (minute) 3 0.5
3Sakekosha (%) 9 18
4 High 1” Mortar 3 Kurami (%) 9 5
8A: Sodium acetate B: Sodium hydroxide

Claims (6)

[Claims] (1) A recording material comprising at least a base material and an ink-receiving layer, characterized in that the amount of a basic compound contained in the ink-receiving layer is 0.5% by weight or less. (2) The recording material according to claim (1), wherein the ink receiving layer is made of a water-soluble or hydrophilic resin. (3) The recording material according to claim (1), wherein the ink-receiving layer contains a cation-modified resin. (4) The ink-receiving layer contains 1.0% by weight or more of a cationic functional group based on the ink-receiving layer.
Recording material described in section 3). (5) The recording material according to claim (1), wherein the ink-receiving layer has water resistance. (6) The recording material according to claim (1), which has an ink transport layer having liquid permeability on the ink receiving layer.