JP2006205447A - Medium to be recorded, improving method of image durability and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique, which is excellent in uniformly coating properties and realizes the improvement of an image quality and of gas resistance in a long-term storage. <P>SOLUTION: In order to improve an image durability, in the pore size distribution of an ink accepting layer, the average pore radius is set to be 5-12 nm and, at the same time, the pore volume having the pore radius of not more than 8 nm is set to be at least 0.1 cc/g and an additive is soluble in an improving liquid of an image durability and a coloring material antidegrader for viscosity-bodying the improving liquid of the image durability as the additive dissolves in the improving liquid of the image durability and, in addition, the improving liquid of the image durability includes at least a non-ionic surface active agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, more preferably, unlike a swelling type such as a water-soluble resin, by applying an image fastness improving liquid to a recorded matter in which an image is formed on a porous ink receiving layer, Generally intended to improve image fastness, a method for improving image fastness that can be uniformly applied, an image fastness improving method excellent in coatability, a recorded matter obtained by this method, and a recording target used in this method It relates to the medium.

  Among various image recording methods, the ink jet recording method is currently widely used, and it is expected that it will be further used in the future. Currently required image characteristics are high-quality images equivalent to silver halide photographic images. Specifically, it has high print density, excellent water resistance, light resistance, gas resistance, and high-quality gloss. It is a high quality image. In particular, high-quality images equivalent to silver salt photographic images are maintained for a long period of time, that is, excellent fastness to deterioration due to gas in the air and deterioration due to water and moisture is required.

Many studies have been made so far to improve image robustness. For example, Japanese Patent Application Laid-Open No. 07-314882 (Patent Document 1) describes that the gas fastness of a recording medium is improved by adding a colorant deterioration preventing agent to the porous ink receiving layer of the ink jet recording medium. Has been. Japanese Patent Application Laid-Open No. 09-48180 (Patent Document 2) discloses a method for protecting a printed matter by coating a protective agent made of a specific resin on the printed matter with aqueous ink. Further, in JP-A-06-301441 (Patent Document 3), after recording on a recording sheet provided with a porous layer made of alumina hydrate on a substrate, the porous layer is impregnated with a curable composition. And a recording method for curing and making transparent has been proposed. Japanese Patent Application Laid-Open No. 2003-118223 (Patent Document 4) and Japanese Patent Application Laid-Open No. 2003-118228 (Patent Document 5) are provided with an ink receiving layer having a porous structure, and the ink receiving layer is image-formed with a color material. For the recorded material, all or substantially all of the color material distributed in the depth direction of the ink receiving layer is in a non-volatile liquid that does not dissolve the color material, such as a fatty acid ester or silicone oil. By filling these non-volatile liquids into the porous structure of the ink-receiving layer as included in the above, gas resistance and glossiness can be obtained without degrading image quality such as image density, color tone and resolution. A technique for improving the image density is disclosed. Japanese Patent Application Laid-Open No. 56-77154 (Patent Document 6) describes that a void in an inkjet sheet having a porous structure is filled with a non-volatile substance.
JP 07-314882 A JP 09-48180 A Japanese Patent Laid-Open No. 06-301441 JP 2003-118223 A JP 2003-118228 A JP-A-56-77154 International Patent Publication No. 01/068377 Pamphlet

  However, there is a demand for a technique for further improving image robustness and long-term storage stability.

  For example, the fading phenomenon that occurs when a recorded image is displayed in a room is various, such as the entire image being reddish, greenish, or the non-printing part turning yellow. In addition to light, there are various factors such as various gases in the air and the effects of temperature and humidity. It is sufficient to add a colorant deterioration preventing agent to an inkjet recording medium. In some cases, image fastness could not be obtained. In addition, there is a problem that the glossiness of the surface of the printed matter may not be sufficiently obtained by the method of coating the protective agent on the printed matter. Japanese Patent Application Laid-Open No. 9-48180 discloses nothing about applying a protective agent to a printed matter formed using a recording medium having an ink receiving layer having a porous structure, and the effect thereof. There is no suggestion. Furthermore, when the inorganic porous layer is impregnated with a curable composition and cured to be transparent, there is a problem that the printed surface may be transparently uneven and unevenness may occur because the curing does not proceed uniformly. there were. Also, WO01 / 068377 (International Patent Publication No. 01/068377 pamphlet: Patent Document 7), a method of treating the surface of a recorded material on which an image is recorded on a recording medium having an ink receiving layer with a natural resin or a synthetic resin, is the same. Discloses a method of treating with a water-soluble resin, a method of treating with fats and oils, and a method of treating with a non-volatile oily substance. By these methods, gas resistance, light resistance, water resistance and heat yellowing are disclosed. Is described as improving. However, although the initial performance was excellent, there were cases where the performance after long-term storage was not sufficient.

  Further, as disclosed in JP-A-2003-118223 (Patent Document 4) and JP-A-2003-118228 (Patent Document 5), inkjet image recording was performed with a dye ink on an ink receiving layer having a gap. Later, by applying an image fastness-improving liquid such as a fatty acid ester, excellent gas resistance, glossiness, and image density were obtained, but also about this after further long-term storage, glossiness, Image density is required. In addition, when the viscosity of the image fastness improving liquid to be applied is low, the image fastness improving to the base paper of the recording medium causes the gas resistance, glossiness, and image density to decrease due to the liquid transfer, thereby improving the image fastness. When the viscosity of the liquid is high, it is difficult to completely fill the gap, and it is not only necessary to apply the pressure manually by a rubbing process or the like, but it also takes time for the application.

  On the other hand, an ink-jet image with a dye ink for an ink-receiving layer that contains a colorant deterioration preventing agent that is soluble in a low-viscosity image-fastness improving liquid and that thickens the image-fastness improving liquid as it dissolves. According to the image fastness improving method of applying the image fastness improving liquid after recording, it is excellent in uniform application property to the ink receiving layer, and the viscosity of the image fastness improving liquid in the ink receiving layer is increased. As a result, it is possible to obtain an image recorded matter having excellent long-term storage stability.

  Also, in order to improve the transparency of the ink receiving layer of the recording medium and achieve further high color development, it is desirable that the pores of the ink receiving layer be as small as possible, taking into account the balance with the ink absorbency. Then, the average pore radius of the ink receiving layer is preferably 5 to 12 nm, and the pore volume having a pore radius of 8 nm or less is preferably 0.1 cc / g or more.

  However, when the ink receiving layer of the recording medium has a pore diameter distribution with an average pore radius of 5 to 12 nm and a pore volume of 8 cc or less and a pore volume of 0.1 cc / g or more, image fastness is obtained. In some cases, the colorant deterioration preventing agent is not sufficiently dissolved in the property improving liquid, so that the image fastness improving liquid does not sufficiently thicken and is transferred to the base paper.

  An object of the present invention is to use a recording medium having an average pore radius of 5 to 12 nm and a pore volume of 0.1 cc / g or more in the pore diameter distribution of the ink receiving layer. Is to provide a technology that is excellent in uniform coating property and that improves image quality and gas resistance in long-term storage.

  In the method of applying a treatment liquid to an ink receiving layer having a porous structure, in order to improve long-term storage, a liquid with improved image fastness with high viscosity suppresses the movement of the treatment liquid in the porous layer. Therefore, the long-term storage stability is improved, but there are cases where uniform coating properties are difficult. In order to achieve high color development by increasing transparency, the pore size distribution of the ink receiving layer is 0.1 cc / pore volume with an average pore radius of 5 to 12 nm and a pore radius of 8 nm or less. In the case of g or more, the elution of the colorant deterioration preventing agent into the image fastness-improving liquid becomes insufficient, so that the image fastness liquid does not sufficiently thicken and shifts to the base paper, and thus stable storage for a long period of time. There was a case of difficulty in sex.

  Therefore, in order to achieve an improvement in image quality (high color development) and an improvement in storage stability over a long period of time while ensuring uniform coating properties, an image fastness improvement liquid and a coating are used. We studied earnestly about recording media. As a result, it contains a colorant deterioration preventing agent that is soluble in the image fastness improving liquid and thickens the image fastness improving liquid as it dissolves. After forming an image with a dye ink on a recording medium having an ink receiving layer having a pore size distribution with a pore volume of 0.1 cc / g or more with a pore radius of 8 nm or less, a low-viscosity image fastness improving liquid is obtained. Applying an image fastness improving liquid containing at least a nonionic surfactant in an image fastness improving method of applying and thickening the applied low-viscosity image fastness improving liquid in the ink receiving layer The present inventors have found that not only gas resistance and image density are improved in the initial stage, but also excellent after long-term storage.

  That is, the present invention includes the following aspects.

  (1) A step of preparing a recording medium having an ink receiving layer containing at least a pigment, a binder, and an additive on at least one surface of a substrate, a step of forming an image with a dye ink, and an image fastness improving liquid A method of improving image fastness comprising at least a coating step of coating the ink receiving layer, wherein the pore diameter distribution of the ink receiving layer has an average pore radius of 5 to 12 nm and a pore volume of not more than 8 nm. 1 cc / g or more, and the additive is a color material deterioration preventing agent that is soluble in the image fastness-improving liquid and that thickens the image fastness-improving liquid as it dissolves. Furthermore, the image fastness improving liquid contains at least a nonionic surfactant.

  (2) The method for improving image fastness according to (1), wherein the nonionic surfactant is a silicone-based surfactant.

  (3) The color material deterioration preventing agent is at least one selected from a hindered amine compound, a phenol compound, a phosphite compound, a thio compound, a benzotriazole compound, and a benzophenone compound. The method for improving image fastness as described.

  (4) The image according to any one of (1) to (3), wherein the colorant deterioration preventing agent dissolves in an amount of 0.1 g to 80 g at 25 ° C. with respect to 100 g of the image fastness improving liquid. Method for improving robustness.

  (5) The image fastness according to any one of (1) to (4), wherein the image fastness improving liquid mainly comprises a fatty acid ester having a viscosity range at 25 ° C. of 15 mPa · s to 300 mPa · s. Improvement method.

  (6) About 5.0 g of the above-mentioned image fastness-improving liquid is accurately weighed and kept open in a dry thermostat at 70 ° C., stored for 500 hours, transferred to a desiccator, and allowed to cool for 30 minutes. 6. The image fastness improving method according to claim 5, wherein a non-volatile rate A (%) of the image fastness improving liquid evaluated by a method of measuring weight is 98.0% or more.

Non-volatile rate A
= {Weight of liquid after storage (g) / weight of target liquid (g)} × 100
(7) A recorded matter created by the image fastness improving method described in (1) to (6) above.

  Improves gas resistance and image density of ink-jet recorded images, and drastically prevents discoloration of images over a long period of time, especially when used for displaying ink-recorded images in ordinary indoor environments such as homes and offices be able to.

  Hereinafter, the image fastness improving liquid according to the present invention will be described.

A: Image Fastness Improvement Liquid First, the image fastness improvement liquid according to the present invention will be described in detail. The image fastness-improving liquid according to the present invention is preferably a fatty acid ester which is mainly in a liquid state at normal temperature (15 to 30 ° C.) and normal pressure, and has low volatility. Here, the non-volatile rate is defined as a value obtained by the following equation.

Non-volatile rate A
= {Weight of liquid after storage (g) / weight of target liquid (g)} × 100
The value of each term in the above formula is measured as follows. That is, about 5.0 g of a sample is accurately weighed in a weighing bottle with a known weight, held open in a dry thermostat at 70 ° C., stored for 500 hours, transferred to a desiccator, allowed to cool for 30 minutes, and then weighted. Measure.

  When the non-volatile rate (A) evaluated by this method is used as a reference, it is preferable that the image fastness improving liquid has a non-volatile rate of A of 98.0% or more and is very difficult to volatilize. This is because the image fastness improving liquid volatilizes after being applied to the recording medium for a long period of time, so that part or all of the liquid disappears by evaporation and voids are formed in the porous layer, causing the image to fade. It is. The image fastness improving liquid according to the present invention may further contain other substances for various purposes as long as the effects of the present invention are not impaired and the coating suitability is not affected. Here, “mainly” means that the content is the largest among the components in the image fastness improving liquid, preferably 50% by mass or more, more preferably 80% by mass, more Preferably, the content is 90% by mass or more, and the image fastness improving liquid includes only a compound having a high non-volatility such as a fatty acid ester.

  The saturated fatty acid constituting the fatty acid ester is preferably a saturated fatty acid having 5 to 18 carbon atoms. It is not preferable from the viewpoints of gas resistance, glossiness, image density, and water resistance that the porous layer is gradually evaporated by the long-term storage after the fatty acid ester is impregnated in the porous layer, thereby causing voids in the porous layer. Furthermore, the molecular weight of the fatty acid ester is preferably 2000 or less, more preferably 1000 or less, considering the viscosity at normal temperature and normal pressure.

  As will be described later, the ink receiving layer of the recording medium according to the present invention contains an inorganic pigment, a binder, a colorant deterioration preventing agent, and the like. In order to achieve a high image density, the pore diameter distribution of the ink receiving layer has an average pore radius of 5 to 12 nm and a pore volume of 0.1 cc / g or more with a pore radius of 8 nm or less. That is, in the porous structure where there are many very small pores, the hydrophilic part where the inorganic pigment is exposed and the hydrophobic part where the coloring material deterioration preventing agent is exposed are microscopically. It is mixed. When an image is formed by ink on the porous layer in which the minute hydrophilic portion and the minute hydrophobic portion are mixed, the solvent component in the ink is dispersed in the micro and exists in the ink receiving layer. Thus, when the image fastness improving liquid according to the present invention is applied to the ink receiving layer in which the solvent component of the ink is dispersed, the ink fastness improving liquid is hydrophobic. In some cases, it is difficult to efficiently and sufficiently impregnate the void portion in the receiving layer with the image fastness-improving liquid and to contact the colorant deterioration preventing agent with the image fastness-improving liquid. That is, the important components of the present invention, that is, the dissolution of the colorant deterioration preventing agent in the image fastness improving liquid and the accompanying increase in the viscosity of the image fastness improving liquid are not sufficiently satisfied, and the effects of the present invention are sufficiently achieved. It may not be possible. In order to solve such problems, in the present invention, it is required as an important component that at least a nonionic surfactant is contained in the image fastness improving liquid. In the present invention, when an image fastness-improving liquid containing at least a nonionic surfactant is used, the solvent component in the ink is dispersed in a porous material in which minute hydrophilic portions and minute hydrophobic portions are mixed microscopically. Even if the ink receiving layer is present, the voids in the ink receiving layer can be efficiently impregnated with the image fastness improving liquid. It is possible to sufficiently achieve the important components of the present invention, that is, the dissolution of the colorant deterioration preventing agent in the image fastness improving liquid and the thickening of the image fastness improving liquid, and the effect of the present invention is achieved. The

  A conventionally well-known thing can be used as a nonionic surfactant based on this invention. For example, silicone surfactants, nonionic surfactants containing polyethylene oxide as hydrophilic groups; ether types such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, acetylene glycol, polyoxyethylene alkyl esters, sorbitan Nonionic surfactants of ester type such as fatty acid ester, amino ether type such as polyoxyethylene alkylamine, and ether ester type such as polyoxyethylene sorbitan fatty acid ester.

  In the present invention, a silicone surfactant is particularly preferably used as the nonionic surfactant. Specific examples of the silicone-based surfactant include those shown below, but the present invention is not limited thereto. L-720, L-7001, L-7002, L-7604, FZ-2123, FZ-2105, Y-7006, FZ2120, FZ-2161, Z-2162, FZ-2163, FZ-2164 and FZ-2166 ( Made by Nihon Unicar).

  The content of the nonionic surfactant in the image fastness improving liquid is preferably in the range of 0.001 to 4.5% by mass. Even if it contains 4.5 mass% or more, the further improvement of the effect of this invention is not seen, and when content is less than 0.001 mass%, the effect of this invention is not acquired.

  The image fastness-improving liquid such as fatty acid ester used in the present invention preferably has a viscosity in the range of 15 to 300 mPa · s at 25 ° C., more preferably in the low to medium viscosity range of 20 to 200 mPa · s. is there. This is because the image fastness-improving liquid in the low-viscosity to medium-viscosity range is excellent in application suitability, and it is also suitable for recording media based on a substrate having an absorptivity such as paper, and resin-coated paper This is also preferable for a recording medium based on a base material that does not have a high absorbability because it can be uniformly applied without taking time and labor.

  Conventionally, when a liquid fastness improving liquid having a low to medium viscosity is applied to a recording medium of a paper base, the liquid fastness improving liquid is transferred to the paper base due to long-term storage, and gas resistance and The image density may decrease, and in particular, there may be a phenomenon in which at least a part of the image portion of the recording medium becomes clouded. In the present invention, the additive contained in the porous layer is an image. In order to increase the viscosity of the image fastness-improving liquid drastically and efficiently in the liquid with improved fastness, the porous layer firmly holds the liquid with improved image fastness even after long-term storage. And image density are improved. In other words, in the present invention, the image fastness-improving liquid is thickened by the dissolution of the additive after coating in the present invention, and the transition to the base paper is less likely to occur. It becomes possible to use the property improving liquid, and this makes it possible to apply easily and in a short time.

  On the other hand, when a low to medium viscosity image fastness improving liquid is applied to a recording medium based on resin-coated paper, the solvent contained in the dye ink driven by the ink jet printer at the time of image formation is Since it remains in the ink receiving layer, the portion cannot be impregnated with the image fastness improving liquid. When stored in that state for a long time, the residual solvent gradually evaporates from the recording medium, so that a sufficient amount of the image fastness-improving liquid is not retained in the ink receiving layer, and the image on the recording medium The phenomenon that at least a part of the part becomes clouded may occur, and it is difficult to evaporate the residual solvent by applying the liquid with high image viscosity in the high-viscosity region over time while applying manual pressure. It was necessary to devise such as to do. However, in the present invention, the additive contained in the porous layer is efficiently and sufficiently dissolved in the image fastness improving liquid, and the viscosity of the image fastness improving liquid is drastically increased. The porous layer firmly holds the image fastness-improving liquid even after the long-term storage even in the image fastness-improving liquid of viscosity, and the gas resistance and the image density are improved.

  The ratio of the molecular weight Ma of the additive dissolved in the image fastness-improving liquid and the molecular weight Mb of the image fastness-improving liquid, that is, the molecular weight ratio L as shown in Formula 1 is 0.5 ≦ L ≦ 10.0 Is preferred.

Molecular weight ratio L = Ma / Mb
In the present invention, the additive dissolves in the image fastness-improving liquid to cause an increase in the viscosity of the image fastness-improving liquid, and the porous layer firmly holds the image fastness-improving liquid even after long-term storage. In order to obtain the effects of the present invention, it is preferable that the thickening width is as large as possible. In order to increase the thickening width in the present invention, the molecular weight of the additive to be dissolved must be large, and preferably 0.5 ≦ L. More preferably, 1.0 ≦ L, and more preferably 2.0 ≦ L. On the other hand, when the molecular weight Ma of the additive is too large, it becomes difficult to dissolve in the image fastness-improving liquid at room temperature, so that the viscosity of the image fastness-improving liquid is not increased and the desired effect cannot be obtained. Therefore, the upper limit of the molecular weight ratio L is preferably L ≦ 10.0, more preferably L ≦ 7.0, and more preferably L ≦ 5.0.

  Whether or not the additive dissolves in the image fastness improving liquid to increase the viscosity of the image fastness improving liquid can be confirmed in a bulk state. That is, when 100 g of fatty acid ester is put into a beaker, and several percent to several tens of percent of the additive is added and dissolved while stirring, the fatty acid ester in which the additive is dissolved is compared with the initial viscosity of the fatty acid ester. It can be confirmed from the measurement with a B-type viscometer that the viscosity is increased. For example, Saracos 6318 (manufactured by Nisshin Oillio Co., Ltd.) is selected as the fatty acid ester, and Adekastab LA-63P (manufactured by Asahi Denka Kogyo Co., Ltd.) is selected as the additive. Saracos 6318 is 100 parts, and LA-63P is 10 parts. When the solution was added and dissolved while stirring, the initial viscosity of Saracos 6318 was 180 mPa · s, whereas the viscosity after dissolution of the additive was 295 mPa · s. Further, when 5 parts of LA-63P was added to 100 parts of Saracos 6318 and dissolved while stirring, the initial viscosity of Saracos 6318 was 180 mPa · s, whereas the viscosity after dissolution of the additive was Was 240 mPa · s.

  When a high-viscosity fatty acid ester of 300 mPa · s or more is used as an image fastness improving liquid, both for a recording medium based on paper and a recording medium based on resin-coated paper, In order to apply uniformly and sufficiently, it is necessary to push in by hand pressure such as rubbing. At this time, it seems that the coating has been sufficiently applied, but when the gas resistance, glossiness and image density after long-term storage are evaluated, a coating defect has occurred at the time of coating, and the image of the part where the void has occurred is caused by ozone. In some cases, the color fading may occur, the glossiness may decrease, or the image density may decrease.

  When a low-viscosity fatty acid ester of 15 mPa · s or less is used as the image fastness-improving liquid, it can easily penetrate even into extremely small pore diameter portions of the porous layer of the recording medium, but the additive dissolves. Since the increase in viscosity is not large, there is evaporability over time, and when applied to a recording medium on a paper base material, the transition to the base paper occurs due to low viscosity. In some cases, the image of the portion where the void is generated may be faded by ozone, the glossiness may be lowered, or the image density may be lowered.

  In addition, regarding the image fastness improving liquid according to the present invention, an additive-containing image fastness improving liquid obtained by dissolving an additive in the image fastness improving liquid in advance has an ink receiving layer to which no additive is added. When applied to a medium, the effects of the present invention may not be sufficiently achieved. As the reason for this, the present inventors speculate as follows. That is, in the present invention, the additive present in the pores (voids) in the ink receiving layer is dissolved by heat treatment, and a part of the dissolved additive oozes out from the pores (voids). In the state, an image fastness improving liquid is applied. Therefore, the contact between the image fastness-improving liquid and the additive in the ink receiving layer, the dissolution of the additive in the image fastness-improving liquid, and the thickening of the image fastness-improving liquid may cause the additive to enter the pores. This is more efficient than the case where it exists in a solid state. If this thickening is viewed from a very local point of view within the pores (voids), it causes a much larger thickening compared to the thickening measured in the bulk. As an effect of such dramatic increase in viscosity, it is considered that in the present invention, the movement of the image fastness-improving liquid in long-term storage in the ink receiving layer is extremely effectively suppressed.

B: Recording medium The recording medium that can be used in the present invention will be described in more detail with reference to preferred embodiments.

  The substrate of the recording medium used in the present invention is not particularly limited, but a paper substrate or resin-coated paper can be used. When paper is used as a base material, there are roughly three forms shown in FIGS. FIG. 3 includes a water coating step before forming the ink receiving layer, an ink receiving layer forming step, and a color material deterioration preventing agent adding step. 4 and 5 show a method for producing a recording medium further including a casting process for imparting surface glossiness, the coloring material deterioration preventing agent may be added either before or after casting. In view of the appearance of the recording medium after finishing, it is preferable to add a colorant deterioration preventing agent before casting. When resin-coated paper is used as a base material, there is a form shown in FIG. FIG. 6 includes an ink receiving layer forming step and a coloring material deterioration preventing agent adding step. By these methods, there is no density distribution in the depth direction of the additive contained in the ink receiving layer of the recording medium, and a recording medium having a so-called uniform density distribution can be obtained. The concentration distribution of the additive was analyzed by line analysis of the cross section of the recording medium for ink by FT-IR microscopic transmission measurement. It can be determined by the change in absorbance at the absorption wavelength based on the functional group presumed to be derived from the additive.

The substrate of the recording medium used in the present invention is not particularly limited, but a paper substrate or resin-coated paper can be used. When a cast process is performed on the surface of the recording medium to form a glossy surface, a fibrous substrate, that is, a paper substrate, is preferable because water and solvent components evaporate from the back surface of the substrate. Paper base materials include those that have been subjected to size press with starch, polyvinyl alcohol, etc. on the base paper, and coated papers such as art paper, coated paper, cast coated paper, etc. that have a coating layer on the base paper It is. When paper is used as the base when the casting process is performed on the surface of the recording medium to form a glossy surface, the thickness of the paper base (the base paper) is such that the cellulose pulp fibers and texture are completely covered The coat layer is preferably provided as an undercoat layer of the ink receiving layer. If it is not covered, uneven coating (such as streak-like defects) is likely to occur due to the fibers and texture when the ink receiving layer is applied. Cellulose pulp fibers in the ink receiving layer or near or on the surface of the ink receiving layer Therefore, even if the surface of the recording medium is cast, it may be difficult to obtain a good and uniform cast surface, that is, a photo-like high gloss surface. In order to cover the cellulose pulp of the paper substrate, the dry coating amount of the coating layer is preferably 10 g / m ² or more, more preferably 15 g / m ² or more. When the dry coating amount is less than 10 g / m ² , it is difficult to completely cover the cellulose pulp fibers and the texture of the base material, which may affect the gloss. When resin-coated paper is used, the base paper of the resin-coated paper is not particularly limited, and a smooth base paper that is generally used is preferable. As the pulp constituting the base paper, natural pulp, regenerated pulp, synthetic pulp or the like is used alone or in combination. This base paper is blended with additives such as sizing agent, paper strength enhancing agent, filler, antistatic agent, fluorescent whitening agent, and dye generally used in papermaking. Further, a surface sizing agent, a surface paper strength agent, a fluorescent brightening agent, an antistatic agent, a dye, an anchor agent, and the like may be coated on the surface. Further, the base paper is preferably one having good surface smoothness, such as being compressed by applying pressure with a calender during or after paper making, and the basis weight is preferably 30 to 250 g / m ² . The resin mainly used for the resin-coated paper is, for example, a polyethylene resin, and low-density polyethylene, medium-density polyethylene, high-density polyethylene, or a mixture thereof can be used as the type. Further, the resin layer of the resin-coated paper may have a single layer or a multilayer of two or more layers. Also in this case, the above polyethylene resins can be used alone or in admixture of two or more. Moreover, it can also be set as the composition from which each layer of a multilayer differs from each other. As a method for forming a resin layer composed of multiple layers, either a coextrusion coating method or a sequential coating method may be employed. Although there is no restriction | limiting in particular as the thickness of the coating resin layer of resin-coated paper, Generally, it coats only the surface or both front and back sides in thickness of 5-50 micrometers. In addition, in the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, stearin Fatty acid metal salts such as magnesium acid, antioxidants such as Irganox 1010 and Irganox 1076, blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue, magenta such as cobalt violet, fast violet, manganese purple Various additives such as pigments and dyes, fluorescent brighteners and ultraviolet absorbers can be added in appropriate combinations. The resin-coated paper used as a support in the present invention is produced by a so-called extrusion coating method in which a heat-melted polyethylene resin is cast on a traveling base paper. In order to improve the adhesion between the resin and the base paper, the base paper is preferably subjected to an activation treatment such as a corona discharge treatment or a flame treatment before coating the resin on the base paper. The surface (surface) on which the ink image-receiving layer of the support is applied has a glossy surface, a matte surface, etc., depending on the application, and a glossy surface is particularly preferably used. Although it is not always necessary to coat the back surface with a resin, it is preferable to coat the resin from the viewpoint of curling prevention. The back surface is usually a matte surface, and an active treatment such as corona discharge treatment or flame treatment can be applied to the front surface or both the front and back surfaces as required. Various back coat layers can be coated on the support for antistatic agent, transportability, anti-curl agent and the like. An inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, latex, a curing agent, a pigment, a surfactant, and the like can be added in an appropriate combination to the backcoat layer.

  The undercoat layer can be formed by a conventionally known coating solution containing a pigment and a binder, but preferably has ink acceptability. One or more undercoat layers can be provided on at least one surface of the substrate. Considering the stability of the environmental curl of the recording medium, the undercoat layer is preferably provided on both the front and back surfaces of the substrate. The base material used in the present invention includes a paper base material provided with the undercoat layer.

  Next, the material for forming the ink receiving layer used in the present invention will be described. The ink receiving layer can be formed by applying a coating liquid containing a pigment and a binder. As the pigment, it is particularly preferable to contain alumina hydrate as a main component in terms of dye fixing property, transparency, printing density, color developability, and glossiness, but the following pigments can also be used. Examples of inorganic pigments include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, magnesium hydroxide, and other organic pigments. Examples thereof include styrene plastic pigments, acrylic plastic pigments, polyethylene particles, microcapsule particles, urea resin particles, and melamine resin particles. One kind selected from these, or two or more kinds selected as necessary can be used in combination.

  As an alumina hydrate, what is represented by following formula (3) can be utilized suitably, for example.

_{Al 2 O 3 -n (OH)} 2 n · mH 2 O
(In the above formula, n represents any of 0, 1, 2, or 3, and m represents a value in the range of 0 to 10, preferably 0 to 5. However, m and n are not 0 at the same time. MH ₂ O often represents a detachable aqueous phase that does not participate in the formation of the crystal lattice, so m can be an integer or non-integer value. M can reach a value of 0 when heated.)
Alumina hydrate is generally produced by hydrolysis of aluminum alkoxide or sodium aluminate as described in US Pat. Nos. 4,242,271 and 4,202,870. Known methods such as a method for performing decomposition, and a method for performing neutralization by adding an aqueous solution such as aluminum sulfate and aluminum chloride to an aqueous solution such as sodium aluminate described in JP-B-57-447605 Can be manufactured. Preferred alumina hydrates in the present invention are alumina hydrates showing a boehmite structure or an amorphous state by analysis by X-ray diffraction, and in particular, JP-A-7-232473 and JP-A-8-132731. And alumina hydrates described in JP-A-9-66664, JP-A-9-76628, and the like.

  In the case where the ink receiving layer is wetted by the rewet method in order to impart gloss to the recording medium surface, it is preferable to use a plate-like alumina hydrate having a small tendency to be oriented. Since the plate-like alumina hydrate has a good water absorbability, the re-wetting liquid easily penetrates, so that the ink receiving layer swells and the alumina hydrate particles are easily rearranged. Therefore, high glossiness can be obtained. Moreover, since the rewetting liquid penetrates efficiently, the production efficiency at the time of casting is also increased.

  In the present invention, polyvinyl alcohol is used as the binder used in the coating liquid for forming the ink receiving layer. The content of polyvinyl alcohol is preferably 5 to 20% by mass with respect to the alumina hydrate. In the present invention, as the binder used in forming the ink receiving layer, a conventionally known binder can be used in combination with the above-described polyvinyl alcohol.

  For the undercoat layer and the above ink-receiving layer, as other additives, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, penetrating agents, colored pigments, coloring Dyes, fluorescent brighteners, ultraviolet absorbers, antioxidants, antiseptics, antifungal agents, water resistance agents, dye fixing agents, and the like can be appropriately contained as necessary.

Including at least one selected from the group consisting of boric acid and borate in the ink receiving layer forming material formed as described above is extremely effective in forming the ink receiving layer. Examples of boric acid that can be used in this case include not only orthoboric acid (H ₃ BO ₃ ) but also metaboric acid and hypoboric acid. The borate is preferably a water-soluble salt of boric acid. Specifically, for example, sodium salt of boric acid (Na ₂ B ₄ O ₇ · 10H ₂ O, NaBO ₂ · 4H ₂ O etc.) and, potassium salt _{(K 2 B 4 O 7 ·} 5H 2 O, alkali metal salts such KBO _2, etc.), an ammonium salt of boric acid _{(NH 4 B 4 O 9 ·} 3H 2 O, NH 4 BO 2 , etc. ), Alkaline earth metal salts such as magnesium salts and calcium salts of boric acid.

  In order to obtain the appropriate coating amount as described above, for example, various blade coaters, roll coaters, air knife coaters, bar coatings are performed in the ink receiving layer and the water coating process described above. Various coating devices such as coaters, rod blade coaters, curtain coaters, gravure coaters, extrusion coaters, slide hopper coaters, and size presses are selected and used as appropriate. It is crafted. At the time of coating, for the purpose of adjusting the viscosity of the coating solution, the coating solution may be heated, or the coater head can be heated.

  For drying after coating, for example, a straight tunnel dryer, an arch dryer, an air loop dryer, a hot air dryer such as a sine curve air float dryer, a dryer using infrared rays, a heated dryer, a microwave, etc., as appropriate. It can be selected and used.

  Furthermore, the additive in this invention is demonstrated. The additive in the present invention refers to a colorant deterioration preventing agent that, when present together with a dye in the ink receiving layer, protects the dye from factors such as gas and light, and improves the weather resistance of the dye. General examples include hindered amine compounds, hindered phenol compounds, benzophenone compounds, benzotriazole compounds, thiourea compounds, thiuram compounds, phosphite compounds, and the like. Is not to be done.

  The organic solvent for dissolving the colorant deterioration preventing agent in the present invention is not particularly limited, but esters such as ethyl acetate and butyl acetate, ketones such as methyl isobutyl ketone, methyl ethyl ketone and acetone, diethyl ether, Examples include ethers such as ethyl methyl ether, and alcohols such as isopropanol, methanol, and ethanol.

In the present invention, as a method for adding the color material deterioration preventing agent to the recording medium, the color material deterioration preventing agent is a color material deterioration preventing agent solution dissolved in at least one kind of organic solvent. After being dissolved in, it may be applied on the formed ink receiving layer. The solid content concentration of the colorant deterioration preventing agent is easily 0.5 to 30% by mass. From the appearance of the recording medium after finishing, the hindered amine coating method is preferably a non-contact coating method with respect to the receiving layer surface, and is not particularly limited, but includes a die coater, an air knife coater, a spray, and the like. A contact-type coating method such as a roll coater, a bar coater, or a gravure coater can also be used. The preferred content of the colorant deterioration preventing agent in the above ink-receiving layer is 0.5 to 10 mass based on the pigment solid content. % Is preferable. By setting it to the above lower limit or more, a sufficient discoloration suppressing effect can be obtained. Further, by setting the amount to be equal to or less than the above upper limit, it is possible to prevent the ink absorbability from being lowered.

  After the colorant deterioration preventing agent is added to the ink receiving layer as described above, a glossy surface can be formed on the surface of the ink receiving layer by a casting method. The casting method is a method in which an ink receiving layer in a wet state or a plastic state is pressure-bonded to a heated mirror-like drum (cast drum) surface, dried in the pressure-bonded state, and the mirror surface is ink-coated. This is a method of copying on the surface of the receiving layer, and there are three typical methods, namely, a direct method, a rewet method (indirect method), and a coagulation method. Any of these casting methods can be used, but is particularly preferable because high gloss can be obtained by using the rewet casting method.

  The recording medium according to the present invention may be provided with a back layer on the back surface of the substrate (the surface opposite to the side on which the ink receiving layer is formed). The formation of the back layer is effective for reducing curling that occurs before and after printing. Considering the curling suppression effect, when the base material is paper, it is preferable that the same surface as the undercoat layer and / or the ink receiving layer on the surface side of the substrate when the moisture is absorbed. It is preferable to use a binder. In particular, it is more preferable to use a pigment or binder of the same type as the material for forming the ink-receiving layer which is a thicker layer. Furthermore, you may provide another layer like the above-mentioned undercoat between the said back surface layer and a base material as needed. In this case, a glossy surface can also be formed on the back surface side, and a recording medium having a glossy surface on both the front and back surfaces can be obtained. In addition, double-sided printing is possible by providing printing performance to the back surface layer, or the back surface layer and / or another layer.

  The additive contained in the ink receiving layer of the recording medium produced by the above process using the above materials does not have a concentration distribution in the depth direction, and is distributed at a so-called uniform concentration. ing. When an image fastness improving liquid according to the present invention is applied to such a recording medium after forming an image with a dye ink, the additive uniformly added in the ink receiving layer improves the image fastness. The liquid is efficiently and sufficiently dissolved in the liquid, and the image fastness-improving liquid is uniformly thickened with the dissolution. As a result, not only can a strong gas resistance be exhibited against the gas entering from the surface of the recorded material, but also a strong gas resistance is exhibited even during long-term storage.

  In addition, the transparency of the ink receiving layer, the ink absorption, the handling property of the recorded matter after the application of the liquid for improving the image fastness, and the retention property of the image fastness improving liquid in the ink receiving layer for a long time. In consideration, the pore size distribution of the ink receiving layer needs to be in a specific range. That is, if the pore diameter is too small, not only the ink absorbability may be lowered, but the applied image fastness improving liquid may not easily penetrate into the ink receiving layer. On the other hand, if the pore diameter is too large, not only the image density may be lowered, but also the applied image fastness improving liquid cannot be held in the ink receiving layer. The image fastness-improving liquid moves to the back, causing the image fastness-improving liquid to pass through, or when the substrate is resin-coated paper, the surface of the recorded material is wetted with the image fastness-improving liquid. May cause poor handling. In consideration of the above, it is preferable that the ink receiving layer of the recording medium has a pore size distribution in which the average pore radius is 5 to 12 nm and the pore volume having a pore radius of 8 nm or less is 0.1 cc / g or more.

C: Recorded matter and image fastness improving method Hereinafter, a detailed description will be given using a cross-sectional view of an example of a recorded matter according to the present invention. For example, as shown in FIG. 1B, the recorded matter according to the present invention includes a porous structure ink receiving layer (1002) including fine particles (1001) on the surface of a support (1000), and the ink receiving layer. An additive (1003) is contained therein, and an image fastness improving liquid (1005) in which the additive can be dissolved after the image is formed by the colorant (1004) adsorbed on the surface of the fine particles is applied. It is. An embodiment in which all or substantially all of the holes distributed in the depth direction of the ink receiving layer are filled with the image fastness improving liquid is more preferable, and the image fastness is improved. Further, the ink receiving layer of the recorded matter according to the present invention is not particularly limited to those containing fine particles as long as it has a porous structure.

  In the case of the above preferred embodiment of the present invention, the reason why the improvement in gas resistance of the recorded matter by the ink formed on the recording medium having the receiving layer is achieved is due to the following mechanism. .

  FIG. 1 schematically shows a cross-sectional structure of a so-called coated paper having a porous layer made of fine particles on a support made of paper or the like. In FIG. 1, reference numeral 1000 denotes a support, and reference numeral 1002 denotes an ink receiving layer held on the support 1000. The ink receiving layer 1002 has a porous structure including fine particles 1001, and the fine particles are fixed by a binder. Then, in the process in which the ink droplets applied to the coated paper soak into the ink receiving layer 1002, the color material 1004 included in the ink is adsorbed on the surface of the fine particles 1001, and an image is formed. When supplying the image fastness-enhancing liquid 1005 to the surface of the recording medium thus recorded, the viscosity of the image fastness-improving liquid is preferably in the low to medium viscosity range (15 to 300 mPa · s). Is a viscosity that is very easy to apply, and does not need to be applied under pressure, and can be easily applied even with a nip pressure such as roller application. As shown in FIG. 1B, the image fastness improving liquid 1005 covers the periphery of the color material 1004 adsorbed on the surface of the fine particles 1001, and the ink receiving layer is uniformly coated with the image fastness improving liquid. Can be completely filled. When the gap is finally filled with the image fastness improving liquid, the coloring material is disconnected from the atmospheric gas or moisture containing them, resulting in deterioration of the coloring material in the ink receiving layer. Is suppressed, and the gas resistance is considered to be improved. In addition, in the present invention, not only this but also the additive 1003 added in the ink receiving layer is efficiently and sufficiently dissolved in the image fastness improving liquid, whereby the viscosity of the image fastness improving liquid increases rapidly. To do. As a result, it is possible to prevent the image fastness-improving liquid from moving from the ink receiving layer to the base paper and the residual ink solvent from moving or evaporating, so that the high performance can be maintained continuously even after long-term storage. A high level of image quality is maintained.

  On the other hand, when the viscosity of the image fastness improving liquid is in a high viscosity range (300 mPa · s or more), it is difficult to apply the liquid, and it is necessary to apply it with pressure. For example, even if it is applied by rubbing by hand, it takes a considerable amount of time and labor, and it is difficult to operate and apply. Even if the image fastness-improving liquid is applied sufficiently, the initial performance is excellent in terms of gas resistance, glossiness, and image density. May shift to the base paper, or the remaining ink solvent may move or evaporate, resulting in a gap corresponding to that portion, which may be a portion not filled with the image fastness improving liquid. In such a case, the cloudiness phenomenon occurs, and the gas resistance, glossiness, and image density are lowered.

  The print density improvement and gloss improvement obtained together with the gas resistance improvement effect according to the present invention are analyzed by the following mechanism. That is, the diffuse reflection of light on the porous layer surface and inside caused by the difference in refractive index between the substance forming the porous layer and the pores (air), here the fine particles and the gap (air), This is considered to be because it is suppressed by being filled with the image fastness improving liquid.

  Hereinafter, embodiments of the application method of the image fastness improving liquid according to the present invention will be described in detail.

  In the present invention, the application method of the image fastness improving liquid is not particularly limited, and can be performed by a known method. Specifically, it can be performed by two application methods, a quantitative application method and an excessive application scraping method. In other words, the quantitative application method is an application method in which an appropriate amount of the image fastness improving liquid can be constantly supplied. It is appropriate to supply the image fastness-improving liquid in an amount that completely fills the pores and an amount that takes into account the amount absorbed by the coating member. For example, in the case of a porous layer containing fine particles In consideration of the porosity (oil absorption amount, etc.) of the porous layer, the amount that completely fills the pores is determined as an appropriate amount. The application means is not particularly limited, and includes roller application, brush application, spray application, spatula application, sponge application, and the like. The excessive coating scraping method is a coating method in which the image fastness-improving liquid is excessively applied and then the amount applied in excess of an appropriate amount, that is, the excessive amount is scraped without damaging the surface of the recording medium. is there. The application means is not particularly limited, and includes roller application, brush application, spray application, spatula application, sponge application, and the like. The scraping means after coating is not particularly limited as long as it does not damage the surface of the recording medium, and can be scraped off by a blade, a spatula, a support plate or the like.

  Specifically, for example, in order to improve the fastness of an image formed on a recording medium having an oil absorption of 0.3 cc, about 0.3 g of an image fastness-improving liquid is applied in a fixed amount or excessively. It is necessary to apply in the porous layer by a coating scraping method. In this way, by sufficiently filling the pores of the porous layer with the image fastness improving liquid, a sufficient effect of improving the fastness can be obtained. This not only covers the surface portion of the porous layer, but also indicates that the effect of the present invention can be achieved by filling the pores of the porous layer with the image fastness improving liquid. is there.

  The present invention will be further described below with reference to examples and comparative examples. First, <Image fastness-improving liquid> and <Additives> and <Recording medium production example> used will be described.

<Image fastness improving liquid>
The following nine types of A-1 to A-5 and B to E were used as the image fastness improving liquid.

{Example of production of image fastness improving liquid A-1}
Capillyl capric acid triglyceride having the following structural formula 1 (trade name: ODO, manufactured by Nisshin Oilio Co., Ltd., molecular weight: 491, viscosity: 22 mPa · s / 25 ° C.) and silicone surfactant FZ-2118 (Nihon Unicar Co., Ltd.) Manufactured) was mixed to prepare an image fastness improving liquid A-1.

{Example of production of image fastness improving liquids A-2 to A-5}
The type of silicone surfactant used in the production example of the image fastness improving liquid A-1 was FZ-2123 and FZ-2162 (both manufactured by Nihon Unicar Co., Ltd.), and the addition amount was changed as shown in Table 1. Except for the above, image fastness improving liquids A-2 to A-5 were prepared in the same manner as in the production example of image fastness improving liquid A-1.

{Image fastness improving liquid B}
In the production example of the image fastness-improving liquid A-1, capryl / capric acid triglyceride is trimethylolpropane triisostearate having the following structural formula 2 (trade name: Saracos 6318, manufactured by Nisshin Oilio Co., Ltd., molecular weight: 934, viscosity : Image fastness-improving liquid B was prepared in the same manner as in the production example of image fastness-improving liquid A-1, except that it was changed to 180 mPa · s / 25 ° C.).

{Image fastness improving liquid C}
In the production example of the image fastness-improving liquid A-1, capryl-capric acid triglyceride was converted to tetra-2-ethylhexanoic acid pentaerythritol having the following structural formula 3 (trade name: Saracos 5408, manufactured by Nisshin Oilio Co., Ltd., molecular weight: 641 and viscosity: 60 mPa · s / 25 ° C.) An image fastness-improving liquid C was prepared in the same manner as in the production example of the image fastness-improving liquid A-1.

{Image fastness improving liquid D}
In the production example of the image fastness-improving liquid A-1, caprylic / capric acid triglyceride is polyglyceryl diisostearate having the following structural formula 4 (trade name: Cosmol 42, manufactured by Nisshin Oilio Co., Ltd., molecular weight: 699, viscosity: 625 mPa · The image fastness-improving liquid D was prepared in the same manner as in the production example of the image fastness-improving liquid A-1, except that s / 25 ° C. was used.

{Image fastness improving liquid E}
In the production example of the image fastness improving liquid A-1, capryl / capric acid triglyceride isononyl isononanoate having the following structural formula 5 (trade name: Saracos 99, manufactured by Nisshin Oilio Co., Ltd., molecular weight: 284, viscosity: 5. The image fastness-improving liquid E was prepared in the same manner as in the production example of the image fastness-improving liquid A-1, except that the image fastness-improving liquid A-1 was changed to 5 mPa · s / 25 ° C.

<Additives>
The following three types A to C were used as additives. The solubility in the image fastness improving liquid is also described.

{Additive A}
Product name: ADK STAB LA-63P (Asahi Denka Kogyo Co., Ltd.)
Molecular weight: about 2000
Melting point: 98 ° C

  Additive A was soluble in the image fastness improving liquids A-1 to A-5 and B to E at 25 ° C.

{Additive B}
Product name: ADK STAB LA-77 (Asahi Denka Kogyo Co., Ltd.)
Molecular weight: 481
Melting point: 84 ° C

  Additive B was soluble in image fastness improving liquids A-1 to A-5, B, D, and E, but was insoluble in image fastness improving liquid C.

{Additive C}
Product name: Antage BHT (manufactured by Kawaguchi Chemical Co., Ltd.)
Molecular weight: 220
Melting point: 69 ° C

  Additive C was soluble in the image fastness improving liquids A-1 to A-5 and B to E at 25 ° C.

<Example of recording medium production>
{Recording medium A}
First, the base material was produced as follows. A pulp slurry comprising 80 parts by mass of hardwood bleached kraft pulp (LBKP) with a freeness of 450 ml CSF (Canadian Standard Freeness) and 20 parts by mass of softwood bleached kraft pulp (NBKP) with a freeness of 480 ml CSF was added to 0.60 cationized starch. After adjusting the stock by adding 10 parts by weight, 10 parts by weight of heavy calcium carbonate, 15 parts by weight of light calcium carbonate, 0.10 parts by weight of alkyl ketene dimer, and 0.03 parts by weight of cationic polyacrylamide, the long net paper machine And made a three-stage wet press and dried with a multi-cylinder dryer. Then, with a size press device, the oxidized starch aqueous solution was impregnated so as to have a solid content of 1.0 g / m ^2, and after drying, machine calendering was performed, the basis weight was 155 g / m ² , the Steecht size degree was 100 seconds, A base material having an air permeability of 50 seconds, a Beck smoothness of 30 seconds, and a Gurley stiffness of 11.0 mN was obtained.

Next, water is applied onto the substrate obtained above with an air knife coater at a wet coating amount of 10 g / m ² at a rate of 30 m per minute, while the paper surface is wet. A receiving layer was formed. The coating liquid and coating method used for forming the ink receiving layer at that time are as follows.

Dispersal HP13 (manufactured by Sasol Co.) as alumina hydrate A was dispersed in water (preferably pure water as a measure against dust for alumina) so that the solid content was 5% by mass, and then hydrochloric acid was added thereto. The pH value was adjusted to 4 and stirred for a while. Thereafter, the dispersion was heated to 95 ° C. while stirring and held at that temperature for 4 hours. Then, while maintaining this temperature, the pH value was adjusted to 10 with caustic soda and stirred for 10 hours, and then the temperature of the dispersion was returned to room temperature and the pH value was adjusted from 7 to 8. Further, desalting treatment was performed, and then acetic acid was added to peptize to obtain a colloidal sol. When the alumina hydrate B obtained by drying this colloidal sol was measured by X-ray diffraction, it showed a boehmite structure (pseudo boehmite). At this time, the BET specific surface area was 143 g / m ² and the pore volume was 0.8 cm ³ / g.

On the other hand, polyvinyl alcohol PVA117 (manufactured by Kuraray Co., Ltd.) was dissolved in water (preferably pure water as a measure against dust against alumina) to obtain an aqueous solution having a solid content of 9% by mass. Then, the colloidal sol of alumina hydrate B prepared above is concentrated to prepare a 22.5 mass% dispersion, and 3% boric acid aqueous solution is added to the solid content of alumina hydrate B. It added so that it might become 0.50 mass% in conversion of boric acid solid content. Thereafter, the obtained boric acid-containing alumina hydrate dispersion and the previously prepared polyvinyl alcohol aqueous solution were mixed with an alumina hydrate solid content and a polyvinyl alcohol solid content ratio of 100: 9 using a static mixer. Immediately after mixing, this was used as a coating solution for the ink receiving layer, and this was applied by a die coater at 30 m / min so that the dry coating amount was 35 g / m ² . And it dried at 170 degreeC and formed the ink receiving layer.

Next, a back layer was formed on the surface of the substrate opposite to the side on which the ink receiving layer was provided as follows. Dispersal HP13 / 2 (manufactured by Sasol Co., Ltd.) as an alumina hydrate is dispersed in water (preferably pure water as an anti-dust measure against alumina) so that the solid content is 18% by mass, and then centrifuged. did. Immediately after mixing this dispersion and an aqueous polyvinyl alcohol solution similar to that used for forming the ink receiving layer with a static mixer so that the ratio of solids of alumina hydrate to polyvinyl alcohol was 100: 9, The coating was performed at 35 m / min with a die coater so that the dry coating amount was 23 g / m ² . And it dried at 170 degreeC, the back layer was formed, and the recording medium A was obtained.

{Recording medium B}
A 5% MIBK (methyl isobutyl ketone) solution of hindered amine compound ADK STAB LA-63P (Asahi Denka Kogyo Co., Ltd.) is applied to the ink receiving layer of recording medium A with a roll coater, and then the excess is scraped off with a Mayer bar. The coating was performed at 60 m / min so that the work amount was 1.3 g / m ^2, that is, 4% by mass based on the pigment solid content. Then, it was dried at 110 ° C. within 5 seconds after coating to obtain the target recording medium B.

{Recording medium C}
A recording medium C was obtained in the same manner as the recording medium B except that the hindered amine compound Adekastab LA-63P was replaced with Adekastab LA-77 (Asahi Denka Kogyo Co., Ltd.).

{Recording medium D}
A recording medium D was obtained in the same manner as the recording medium B except that the hindered amine compound ADK STAB LA-63P was replaced with ANTAGE BHT (manufactured by Kawaguchi Chemical Co., Ltd.).

{Recording medium E}
First, a white PET film (Melinex 339 thickness: 110 μm, manufactured by IC Corporation) was prepared as a base material, and an ink receiving layer was formed on the base material. The coating liquid and coating method used for forming the ink receiving layer at that time are as follows.

The colloidal sol of alumina hydrate B prepared in the production example of the recording medium A was concentrated to prepare a 22.5 mass% dispersion, and a 3% boric acid aqueous solution was added to the solid of alumina hydrate B. It added so that it might become 0.50 mass% in conversion of boric acid solid content with respect to a part. Thereafter, the obtained boric acid-containing alumina hydrate dispersion and the previously prepared polyvinyl alcohol aqueous solution were mixed with an alumina hydrate solid content and a polyvinyl alcohol solid content ratio of 100: 9 using a static mixer. Immediately after mixing, this was used as a coating solution for the ink receiving layer, and this was applied by a die coater at 30 m / min so that the dry coating amount was 35 g / m ² . And it dried at 80 degreeC and the ink receiving layer was formed, and the recording medium E was obtained.

{Recording medium F}
A 5% MIBK (methyl isobutyl ketone) solution of a hindered amine compound ADK STAB LA-63P (Asahi Denka Kogyo Co., Ltd.) is applied to the ink receiving layer of the recording medium E with a roll coater, and then the excess is scraped off with a Mayer bar. The coating was performed at 60 m / min so that the amount was 1.3 g / m ^2, that is, 4% by mass based on the pigment solid content. And it dried at 80 degreeC within 5 second after coating, and the target recording medium F was obtained.

  As described above, in each of the obtained recording media A to F, the average pore radius of the ink receiving layer is 8.8 to 9.4 nm, and the pore volume of the pore radius of 8 nm or less is 0.1 cc / g or more.

<Examples 1-13 and Comparative Examples 1-2>
(Creation and evaluation of recorded materials)
On the recording medium created above, a recorded matter in which an image was recorded by the following method in a 30 ° C./80% RH environment was created, and an image fastness improving liquid was used for the recorded matter, Various image fastness tests were performed according to the following evaluation methods (1) to (3).

  Using a genuine black ink for a photo printer (trade name: BJ-950i; manufactured by Canon) using an ink jet method, a 150% printed portion of 6 cm square was printed with monochromatic black, and each test was performed. . Note that the ink used for printing is a genuine product of the printer and is a water-based ink containing a water-soluble dye. Further, the various image fastness improving liquids described above were applied to the surface of the ink receiving layer of the recorded matter at a rate of about 0.3 g per area of 126 mm × 89 mm. The coating method performed the coating process using the coating roller having the configuration shown in FIG. At this time, the paper passing speed in the image fastness coating step was 5 mm / sec. Thus, each recorded matter of Examples 1 to 13 and Comparative Examples 1 and 2 was obtained by combining the image fastness improving liquid and the recording medium as shown in Table 3 below.

(Test method)
(1) Gas resistance test An ozone exposure test was performed using an ozone tester (manufactured by Suga Test Instruments Co., Ltd., trade name: ozone weatherometer).

Test conditions;
Exposure gas composition: Ozone 3ppm
Test time: 6 hours Temperature and humidity conditions in the test layer: 45 ° C., 55% RH
Gas resistance evaluation;
The chromaticity (Lab) before and after the ozone exposure test in the printed part was measured using a spectrophotometer / Spectrino (manufactured by Gretag Macbeth) and evaluated by the color difference ΔE calculated therefrom. In the measurement, five points were measured in a region 1 cm or more from the boundary of the printed portion, and the average value was obtained as chromaticity. The results are shown in Table 4. In addition, the evaluation result was described based on the following criteria.

○: ΔE = less than 2.0 ○ △: ΔE = 2.0 or more and less than 3.0 Δ: ΔE = 3.0 or more and less than 5.0 ×: ΔE = 5.0 or more (2) Image density It measured using the photometer and spectrino (made by Gretag Macbeth). In the measurement, five points were measured in an area 1 cm or more from the boundary of the print portion, and the average value was obtained as the image density. The results are shown in Table 4.

(3) Uniform applicability Visual evaluation was performed on the uniform applicability when the image fastness improving liquid was applied to the print portion. The evaluation criteria are ○ when the coating is completely uniform, not completely coating, but △ the level that seems to be practically acceptable, and the case where a missing part with poor coating can be confirmed even a little. X. The results are shown in Table 4.

  Further, the same test methods and standards for the gas resistance and image density of each recorded material after newly storing the recorded materials of Examples 1 to 13 and Comparative Examples 1 and 2 in a 24 ° C./60% RH environment for 90 days. It was evaluated by. The results are also shown in Table 4.

  As shown in Table 4, according to the image forming method using the inkjet recording medium according to the present invention, the uniform coating property is good, the initial image characteristics and the gas resistance are excellent, and after long-term storage. It is possible to create a recorded matter having excellent image characteristics and gas resistance.

When the additive in the ink receiving layer has a uniform density distribution in the depth direction and is uniform, the image fastness-improving liquid is applied after the image is recorded on the recording medium according to the present invention. A state of a cross section of a recording medium is schematically shown. It is a figure which shows the structure of the roller for application | coating. It is a schematic process drawing which shows the manufacturing process of a recording medium. It is a schematic process drawing which shows the manufacturing process of a recording medium. It is a schematic process drawing which shows the manufacturing process of a recording medium. It is a schematic process drawing which shows the manufacturing process of a recording medium.

Explanation of symbols

1 Liquid with increased robustness
2 Kakitori blade
3 Transport roller
4 Application amount regulating blade
5 Application roller
6 Opposing roller
7 Recording medium

Claims (7)

  A step of preparing a recording medium having an ink receiving layer containing at least a pigment, a binder, and an additive on at least one surface of a base material, a step of forming an image with a dye ink, and an image fastness improving liquid are applied A method of improving image fastness comprising at least a coating step, wherein in the pore diameter distribution of the ink receiving layer, the pore volume having an average pore radius of 5 to 12 nm and a pore radius of 8 nm or less is 0.1 cc / g. In addition, the additive is a colorant deterioration preventing agent that is soluble in the image fastness-improving liquid and that thickens the image fastness-improving liquid as it dissolves. An image fastness improving method, wherein the image fastness improving liquid contains at least a nonionic surfactant.   The method for improving image fastness according to claim 1, wherein the nonionic surfactant is a silicone surfactant.   3. The image fastness according to claim 1, wherein the colorant deterioration preventing agent is at least one selected from a hindered amine compound, a phenol compound, a phosphite compound, a thio compound, a benzotriazole compound, and a benzophenone compound. How to improve.   4. The method of improving image fastness according to claim 1, wherein the colorant deterioration preventing agent dissolves in an amount of 0.1 g to 80 g at 25 ° C. with respect to 100 g of the image fastness improving liquid.   The image fastness-improving method according to claim 4, wherein the image fastness-improving liquid is mainly composed of a fatty acid ester having a viscosity range at 25 ° C of 15 mPa · s to 300 mPa · s. About 5.0 g of the above-mentioned image fastness improving liquid is accurately weighed and held open in a dry thermostat at 70 ° C., stored for 500 hours, transferred to a desiccator, allowed to cool for 30 minutes, and then weighed. 6. The image fastness improving method according to claim 5, wherein a non-volatile rate A (%) of the image fastness improving liquid evaluated by the method is 98.0% or more.
Non-volatile rate A
= {Weight of liquid after storage (g) / weight of target liquid (g)} × 100   A recorded matter created by the method for improving image fastness according to claim 1.

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