JP3059474B2 - Ink jet recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a recording medium for performing recording using an aqueous ink, and more particularly to an ink jet recording medium suitable for color image recording using an aqueous ink using paper or a film as a support.

[Prior art and its problems]

Ink jet recording is a method in which fine droplets of ink are caused to fly according to various operating principles and adhere to a recording medium to record characters, images, and the like. Because of its simplicity, it has rapidly spread in various applications as a hard copy device for various figures and color images including kanji. In addition, an inkjet recording medium for an overhead projector using a light-transmitting film as a support is used in many conferences, lectures, briefing sessions, product advertisements, and the like along with photographic slides. Producing a medium by an ink jet recording method has many advantages. Conventionally, efforts have been made in terms of devices and ink compositions to use high-quality paper or coated paper used for ordinary printing and writing as an inkjet recording material. However, with the improvement of the performance of the inkjet recording apparatus such as high-speed, high-definition, full-color, etc. of the apparatus, and expansion of applications, more advanced characteristics are required for the recording medium. That is, as the recording material, the density of the ink dots is high, the color tone is bright and vivid, the ink does not flow or bleed even when the ink dots are superimposed and the ink dots overlap, It is required that the diffusion in the lateral direction is not unnecessarily large and that the periphery is smooth and not blurred. Several proposals have hitherto been made to solve these requirements. For example, JP-A-53-49113 discloses an ink jet recording paper in which a sheet containing a urea-formalin resin powder impregnated with a water-soluble polymer is disclosed. There are disadvantages that the periphery is easily blurred and the dot density is low. JP-A-55-5830 discloses an ink-jet recording paper provided with an ink-absorbing coating layer on the surface of a support, and JP-A-55-51583 discloses an amorphous pigment as a pigment in a coating layer. An example using silica powder is disclosed in JP-A-59-174381.
Nos. 60-44389, 60-132785, and 60-171143 disclose an ink jet recording sheet provided with a transparent ink receiving layer. These coated paper type ink jet recording media are improved in terms of dot diameter, dot shape and print density compared to general paper type ink jet paper, but are still insufficient in terms of ink absorption speed, Especially when high-speed multicolor color recording, etc., dots of multiple water-based inks overlap, ink bleeding occurs, and ink is transferred to the guide rollers of the recording device due to insufficient drying properties of the ink, resulting in a recorded image. In some cases, such as the contamination of On the other hand, with regard to an inkjet recording material for an overhead projector using a transparent support, the use of an ink-absorbing inorganic pigment or the like cannot be used in a large amount because the transparency is hindered, and the ink-absorbing property is limited. It depends on the properties of the resin formed on the transparent support. Conventional resins used for such purposes include:
For example, JP-A-57-38185 discloses polyvinylpyrrolidone or polyvinylpyrrolidone-vinyl acetate copolymer, JP-A-60-234879 discloses a copolymer of polyvinyl alcohol and olefin or styrene and maleic anhydride, JP-A-61-74879 discloses providing a crosslinked layer of an ethylene oxide polymer and an isocyanate compound. JP-A-61-181679 discloses the use of a blend of carboxymethyl cellulose and polyethylene oxide. No. 61-132377 discloses the use of polyvinyl alcohol grafted with methacrylamide. In the case of an inkjet recording medium using such a hydrophilic resin, when a layer is formed on a transparent support alone with a resin alone as long as the transparency is not impaired for an overhead projector, the ink absorption speed is not sufficient, and the ink dot At present, there are many problems such as bleeding, drying property, water resistance of recorded images, and stickiness of the surface. As described above, such as applicable to both transparent supports such as paper or film, it has excellent ink absorption, prevents bleeding of ink dots, and has excellent ink drying properties and excellent translucency. At present, there is no satisfactory ink-jet recording material.

[Means to solve the problem]

The present invention solves various problems related to the present invention by using a resin composition having excellent transparency and high ink absorption ability, which is applicable to both a paper support and a transparent support such as a film. Things. That is, in an ink jet recording solvent having at least one ink-receiving layer on a support such as paper or film and forming a recorded image using an aqueous ink containing a water-soluble dye, the ink-receiving layer has 100% of all monomers. Contains a copolymer obtained by copolymerizing at least 10 parts by weight of a monomer selected from the following compound (I) and 0.1 to 10 parts by weight of a polyfunctional vinyl monomer selected from the following compound (II) based on parts by weight And, the copolymer is soluble in a solvent in a monomer state at the time of its synthesis, but uses a solvent that becomes insoluble in a solvent when a polymer is formed, and has a solvent solubility in the system in advance. An ink jet recording material characterized by being obtained by forming a copolymer in the form of fine particles by the presence of a resin. Compound (I) p-styrenesulfonic acid and its alkali metal salt, (meth) acrylamide, (meth) acrylic acid and their metal salts or neutralized salts with organic amines, 2-acrylamido-2-methylpropanesulfonic acid and its salts Alkali metal salts or neutralized salts with organic amines Compound (II) Divinylbenzene, methylenebisacrylamide, ethylene glycol di (meth) acrylate, vinyl (meth) acrylate The role of compound (I) is the resin composition to be formed It is an essential component for imparting good hydrophilicity to the product and increasing absorption of the aqueous ink. The role of compound (II) is to provide a high water absorption capacity by adding an appropriate crosslinking point to the resin composition,
It is an essential component for controlling the absorption rate of aqueous ink and the spread of ink dots. Compound (I) in the copolymer composition used in the present invention
The ratio of the compound (I) is at least 10 parts by weight and the amount of the compound (II) is 0.1 to 10 parts by weight. Sufficient affinity for ink cannot be obtained, resulting in poor ink absorbency. If the proportion of the compound (II) is out of the above range, the ink absorption rate is insufficient, causing problems such as blurring of the image. The copolymer synthesized by a combination of arbitrary monomers selected from the compounds (I) and (II) has a crosslinked structure, and it is difficult to synthesize in a solution form by a homogeneous solution polymerization using an ordinary aqueous solvent. . That is, in a system containing a relatively large amount of compound (II), the crosslinking reaction proceeds in parallel with the polymerization reaction, so that the entire system becomes a gel before the polymerization is completed,
Often solidifies. It is also conceivable to use such a gel-like substance in a state in which a powder and a resin obtained by drying and pulverizing the gel-like substance are dispersed.However, when this is applied on paper or film and used as an ink absorbing layer, Although there is no problem in terms of ink absorption speed, since the powder particle size is relatively large, the coating film thickness is not uniform, and undesired disadvantages such as uneven ink absorption and occurrence of bleeding have occurred. Therefore, the present inventors have conducted further intensive studies, and as a more preferable resin, even if the copolymer composition is the same as the above-mentioned polymer, as a solvent used in polymerization, a water-miscible organic solvent It has been found that it is effective to prevent the entire system from gelling by synthesizing the resulting polymer in the form of fine particles or dispersion from the system using a mixed solvent of (1). That is, the polymer thus obtained is in a dispersed state at the time of polymerization,
After the polymerization is completed, the organic solvent is removed or water is added to dilute the solution, and when the degree of cross-linking is uniform or the degree of cross-linking is large, the solution can be stably dispersed in fine particles. As described above, in order to form the produced polymer in a dispersed state or in the form of fine particles, it is important to select a solvent that is soluble in a solvent in a monomer state, but insoluble in the solvent when the polymer is formed. Examples of such a solvent include a system in which an alcohol such as methanol, ethanol, or isopropanol is added to water, or a mixed solvent in which an organic solvent such as water / dioxane, water / acetone or the like which is miscible with water is added. It is particularly preferred to carry out the polymerization using. The mixing ratio of such an organic solvent and water should be selected so as to substantially dissolve the monomer mixture at least before the start of the polymerization and at least partially insolubilize the polymer formed during the polymerization. The use of is preferred. Further, from the viewpoint of easy handling of the organic solvent used, the use of alcohol is most preferable. Furthermore, when a resin having solubility in a solvent is added to the system in advance before the start of polymerization when performing polymerization in the system as described above, it is possible to stably precipitate the polymer to be formed into fine particles. . Examples of the resin having such an effect include resins such as polyvinyl alcohol and polyvinylpyrrolidone, but there is no particular limitation as long as the resin is at least soluble in the solvent used. The proportion of the resin that should be pre-existing in such a system depends on the total monomer 10 used in the polymerization.
0 parts by weight, preferably 100 parts by weight or less,
Further use may cause the effects of the present invention to be lost. When such a resin is added to the system in advance and polymerization is performed, the resulting polymer is often obtained as a stable fine particle dispersion. Although it is also possible, it is also possible to obtain a coating liquid which is uniformly dissolved or distilled out by distilling the organic solvent used from the system or diluting the same with water or when the degree of crosslinking is large, thereby stably dispersing the coating liquid. . The resin composition according to the present invention is basically composed of a copolymer obtained by copolymerizing two or more monomers selected from the compounds (I) and (II). It is also possible to form a multi-component copolymer by selecting two or more monomers from one or each of the above. Alternatively, it is also possible to introduce a monomer of the third component as a monomer following the compounds (I) and (II) for various purposes. Examples of the monomer of the third component include those having various alkyl groups such as methyl (meth) acrylate in the ester residue, N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate Alternatively, quaternary salts thereof, styrene and derivatives thereof, vinyl acetate, maleic acid, crotonic acid, (meth) acrylonitrile and others can be mentioned. Such a monomer of the third component can be used if necessary, but the ratio of the monomer to 100 parts by weight of the total monomer is preferably 40 parts by weight or less. May lose its effect. Further, after the polymerization is completed, various water-soluble polymers can be added to the coating liquid containing the copolymer for the purpose of improving the film properties and other purposes. Examples of such water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, gelatin and derivatives thereof, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, sodium and ammonium salts of carboxymethylcellulose, various water-soluble polymers such as sodium polyacrylate and starch. Although a polymer can be used, it is preferable to use it in a range of 100 parts by weight or less based on the total amount of all monomers constituting the copolymer resin composition obtained in the present invention. Further, for the purpose of improving the image storability after inkjet recording, it is also possible to add an ultraviolet absorber, an antioxidant, a waterproofing agent and the like. As a method for producing the ink jet recording medium of the present invention, when paper is used as a support, the copolymer resin composition according to the present invention is used alone or together with an ink-absorbing inorganic pigment or the like as a coating liquid to form a coating liquid. It can be formed by coating and drying on paper using an apparatus. When using a light-transmitting support such as a film, the copolymer resin composition according to the present invention is used alone or as a coating liquid together with a water-soluble polymer or other additives within a range that does not impair the light-transmitting property. It is possible to manufacture by applying and drying according to the application method. The dry thickness of the ink receiving layer thus formed is desirably in the range of 3 to 12 microns, and in order to further improve the curl of the support, a similar resin layer or a similar resin layer is provided on the surface opposite to the ink receiving layer. A layer made of another water-soluble polymer may be formed.

【The invention's effect】

By forming a layer containing the copolymer composition according to the present invention as an ink receiving layer on a support, such a resin composition can be uniformly applied, and a portion having a high hydrophilicity in the resin composition. Since it also contains a cross-linked component that greatly contributes to water absorption, the ink absorption rate is extremely excellent,
Provides a light-transmitting film that excels in ink drying properties and does not cause bleeding of ink dots, can be applied to both supports such as paper and film, and is extremely excellent as an ink jet recording material using an aqueous ink. .

【Example】

Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples and Examples, but the effects are not limited to these examples. (Synthesis Example 1) 80 g of sodium p-styrenesulfonate and 20 g of polyvinyl alcohol (PVA103, manufactured by Kuraray Co., Ltd.) were charged into a 500 ml four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser, and distilled water was 120 g. And 160 g of ethanol, and dissolved at 75 ° C. Under a nitrogen atmosphere, 1.5 g of AIBN was added, and 1.5 g of methylenebisacrylamide was added little by little over 1 hour, followed by heating and stirring at this temperature for 3 hours. The product was a white dispersion, which was poured into water to obtain a uniform polymer solution with a solid content of 17%. (Synthesis Example 2) Similarly to Synthesis Example 1, polyvinyl alcohol (PVA203,
10 g of Kuraray Co., Ltd., 80 g of potassium p-styrenesulfonate and 20 g of acrylamide were dissolved in 130 g of distilled water and 150 g of isopropanol, and 5 g of divinylbenzene was added dropwise in small amounts over 2 hours. A white emulsion was obtained. Add water to this, solid content 17%
Was obtained. (Synthesis Example 3) As in Synthesis Example 1, 7 g of polyvinylpyrrolidone, 75 g of acrylamide, 20 g of sodium methacrylate and 5 g of styrene were taken, and 150 g of distilled water and 16 g of isopropanol were added thereto.
0 g and 2 g of ethylene glycol dimethacrylate 2 g
Polymerization was carried out in the same manner at 75 ° C. while dripping over time to obtain a white emulsion. Thereafter, isopropanol was distilled off under reduced pressure, and distilled water was further added to obtain a dispersion having a solid content of 17%. (Synthesis Example 4) As in Synthesis Example 1, sodium methacrylate 25
g, potassium 2-acrylamide-2-methylpropanesulfonate 35 g, N, N-dimethylaminoethyl methacrylate hydrochloride 10 g, vinyl methacrylate 2 g and polyvinyl alcohol 35 g, and 150 g of distilled water and 100 g of dioxane were added. Polymerized. After polymerization,
Dioxane was distilled off under reduced pressure, and water was further added to obtain a dispersion having a solid content of 17%. Example 1 Each of the resin solutions obtained in Synthetic Examples 1-4 was used as base paper using high-grade paper (basis weight 60 g / m ² ) having a Steckigt sizing degree of 0 seconds.
A liquid mixed with 100 parts and 50 parts of synthetic amorphous silica (Fine Seal X-37B, manufactured by Tokuyama Soda Co., Ltd.) was used as a coating liquid.
It was applied to a solid content of 10 g / m ² with an air knife coater and dried. After applying the super calendar finish, each sample was recorded as an inkjet recording material with an inkjet printer IO-735 manufactured by Sharp Corporation.There was no spread or unevenness of the ink, high resolution ink absorption and drying. A good color image without any problem was obtained. Example 2 The resin solutions obtained in Synthetic Examples 1-4 were individually applied to a water-based undercoat-treated polyethylene film so as to have a dry film thickness of 5 μm, and dried. When color images were recorded on each sample using the inkjet printer IO-735 manufactured by Sharp Corporation in the same manner as in Example 1, the transparency of all the samples was good, and the ink absorption rate and ink drying property were sufficiently fast. As a result, good color image recording with high resolution and high color density without blurring of the image was obtained.

Claims (5)

(57) [Claims] 1. An ink-jet recording medium having at least one ink-receiving layer on a support and forming a recorded image using an aqueous ink containing a water-soluble dye, wherein the ink-receiving layer comprises 100 parts by weight of all monomers. Contains a copolymer obtained by copolymerizing at least 10 parts by weight of a monomer selected from the following compound (I) and 0.1 to 10 parts by weight of a polyfunctional vinyl monomer selected from the following compound (II), In addition, the copolymer is soluble in a solvent in a monomer state at the time of its synthesis, but a solvent that is insoluble in a solvent forming a polymer is used. An ink jet recording medium characterized by being obtained by producing a copolymer in the form of fine particles by the presence of a. Compound (I) p-styrenesulfonic acid and an alkali metal salt thereof, (meth) acrylamide, (meth) acrylic acid and a metal salt thereof, or a neutralized salt with an organic amine, 2-acrylamido-2-methylpropanesulfonic acid and Compound (II) divinylbenzene, methylenebisacrylamide, ethylene glycol di (meth) acrylate, vinyl (meth) acrylate 2. The ink jet recording medium according to claim 1, wherein the solvent is a water-miscible organic solvent. 3. The ink jet recording medium according to claim 1, wherein the water-miscible organic solvent is alcohol, acetone or dioxane. 4. The ink jet recording medium according to claim 1, wherein the resin soluble in a solvent is polyvinyl alcohol or polyvinyl pyrrolidone. 5. A resin having solubility in a solvent is added to all the monomers 10
5. The ink jet recording medium according to claim 1, which is used in an amount of 1 part by weight or more and 100 parts by weight or less based on 0 part by weight.