JP4298426B2 - Image robustness improvement method - Google Patents

Description

  The present invention relates to an image fastness improving method in which an image fastness improving liquid is formed after ink image formation. More preferably, unlike the swelling type such as a water-soluble resin, the image fastness is generally applied by applying an image fastness improving liquid to a recorded matter in which an image is formed on a porous ink receiving layer. The present invention relates to a method for improving image fastness, which is intended to improve the coating property and is excellent in coating property and can be applied uniformly.

  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 material 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, and it is sufficient to add a coloring material deterioration preventing material 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. Also, when the viscosity of the image fastness improving liquid to be applied is low, gas fastness, glossiness and a decrease in image density are caused by the transfer of the image fastness improving liquid to the base paper of the recording medium. When the viscosity of the improving liquid is high, it is difficult to completely fill the voids, and it is not only necessary to apply by applying a manual pressure by a rubbing process, but also it takes time for the application.

  As described above, in the technology disclosed in the related art, by processing the image surface with a low-viscosity processing liquid after forming an image on the porous layer, A) improvement in initial image quality, improvement in gas resistance, B) Satisfies at least the performance of B) among A) to C), such as improvement in image quality in long-term storage, improvement in gas resistance, and C) excellent uniform coatability, and preferably in addition to B) in addition to A) And a technique that satisfies at least one of C) is not known.

  An object of the present invention is to provide a technique capable of satisfying at least one performance of A) to C), preferably two or more of these simultaneously. For example, it is an object to satisfy the performance of B) by processing the image surface with a liquid processing solution after forming an image on the porous layer, and preferably satisfies the performance of A) and C) at the same time. The challenge is to make it better.

  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. Therefore, in order to achieve an improvement in image quality and long-term storage stability of the image quality while ensuring uniform coatability using a low-viscosity image fastness-improving liquid, an extensive study was conducted on the ink receiving layer of the recording medium. . As a result, an anti-coloring material that is soluble in fatty acid esters is contained in the ink receiving layer, and the applied low-viscosity image fastness-improving liquid is thickened in the ink receiving layer, so The present inventors have found that not only gas properties, glossiness and image density are improved, but also excellent after long-term storage, and even water resistance is improved. Further, since the viscosity of the image fastness-improving liquid before coating may be low, the uniform application property of the image fastness-improving liquid is excellent, and this knowledge has also become the basis for the present invention.

前記色材劣化防止材は、前記インク受容層の深さ方向に関して減少する分布で存在し、
前記色材劣化防止材の分子量Ｍａと前記画像堅牢性向上液体の分子量Ｍｂの下記式（１）で表わされる分子量比Ｌが０．５≦Ｌ≦１０．０の範囲にあることを特徴とする画像堅牢性向上方法。
分子量比 Ｌ＝Ｍａ／Ｍｂ・・・式（１）
［２］前記色材劣化防止材が、前記画像堅牢性向上液体１００ｇに対して２５℃において、０．１ｇ以上８０ｇ以下で溶解する［１］に記載の画像堅牢性向上方法。
［３］前記画像堅牢性向上液体を７０℃の乾式恒温槽に開放状態で保持し、５００時間保存した後に試料をデシケーターに移し、３０分間放冷した後に重量を測定することにより求められる前記画像堅牢性向上液体の下記式（２）で表わされる不揮発率Ａ（％）が、９８．０％以上である［１］または［２］に記載の画像堅牢性向上方法。
不揮発率Ａ＝[保存後の液体の重量（ｇ）／対象となる液体の重量（ｇ）]×１００・・・（２）。 That is, the present invention includes the following aspects.
[1] An image in which an image fastness improving liquid is applied to an ink receiving layer on an image-formed surface after an image is formed with a dye ink on a recording medium having an ink receiving layer provided on at least one surface of a substrate. A method for improving robustness,
The image fastness-improving liquid comprises caprylic / capric triglyceride, trimethylolpropane triisostearate, penta 2-ethylhexanoate as a fatty acid ester having a viscosity range at 25 ° C. of 15 mPa · s to 300 mPa · s. It is one kind selected from Erislit,
The ink receiving layer contains at least a pigment, a binder, and a colorant deterioration preventing material,
It said colorant deterioration preventing agent, the image is soluble in fastness improving liquid, and the image fastness improving following formula with the dissolution in the liquid to thicken the image fastness improving liquid (A) ~ At least one selected from compounds represented by (C) ,

The color material deterioration preventing material exists in a distribution that decreases in the depth direction of the ink receiving layer,
The molecular weight ratio L represented by the following formula (1) between the molecular weight Ma of the colorant deterioration preventing material and the molecular weight Mb of the image fastness improving liquid is in the range of 0.5 ≦ L ≦ 10.0. Image fastness improvement method.
Molecular weight ratio L = Ma / Mb (1)
[2] The method for improving image fastness according to [1], wherein the colorant deterioration preventing material 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.
[3] The image obtained by holding the image fastness-improving liquid in a dry thermostat at 70 ° C. in an open state, storing the sample for 500 hours, transferring the sample to a desiccator, allowing to cool for 30 minutes, and measuring the weight. The method for improving image fastness according to [1] or [2], wherein the non-volatile rate A (%) represented by the following formula (2) of the fastness improving liquid is 98.0% or more.
Non ratio A = [after storage of the liquid weight (g) / subject to the weight of the liquid (g)] × 100 ··· ( 2).

  After an ink image is formed on a recording medium having an ink receiving layer provided on at least one surface of the substrate, an ink fastness-improving liquid is applied to the ink receiving layer on the image formed surface. The additive contained in the layer dissolves in the image fastness-improving liquid, and the viscosity of the image fastness-improving liquid is increased along with the dissolution, whereby the gas resistance, glossiness, and image density of the ink recorded image are increased. In particular, even if the ink-recorded image is used for display in a normal indoor environment such as a home or office, it is possible to dramatically prevent the image from fading over a long period of time.

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 (2).
Nonvolatile rate A = [weight of liquid after storage (g) / weight of target liquid (g)] × 100 (2).

  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.

  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, etc. 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 an image fastness-improving liquid in a low to medium viscosity range is applied to a recording medium on a paper substrate, the image fastness-improving liquid migrates to the paper substrate due to long-term storage, resulting in gas resistance. The glossiness, glossiness, and image density may be poor, and in particular, at least a part of the image portion of the recording medium may be clouded. However, in the present invention, it is contained in the porous layer. The additive for preventing colorant deterioration dissolves in the liquid with improved image fastness and dramatically increases the viscosity of the liquid with improved image fastness, so that the porous layer holds the liquid with improved image fastness even after long-term storage. Thus, the gas resistance, glossiness, and image density are excellent, and the water resistance is improved by increasing the viscosity of the image fastness improving liquid. 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 an image fastness-improving liquid in the low to medium viscosity range is applied to a recording medium based on resin-coated paper, it is contained in the dye ink driven by an ink jet printer during image formation. Since the solvent 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 dissolved in the image fastness improving liquid and the viscosity of the image fastness improving liquid is dramatically increased. The porous layer firmly holds the image fastness-improving liquid even after long-term storage even with the image fastness-improving liquid, and is excellent in gas resistance, glossiness, image density, and water resistance.

  The ratio of the molecular weight Ma of the additive dissolved in the image fastness improving liquid to the molecular weight Mb of the image fastness improving liquid, that is, the molecular weight ratio L as shown in the formula (1) is 0.5 ≦ L ≦ 10.0. Preferably there is.

Molecular weight ratio L = Ma / Mb (1)
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.

  Further, a more preferable aspect of the present invention is a case where the additive has a distribution in which the additive decreases in the depth direction of the porous layer. The additive is most densely distributed near the surface of the recording medium. Since the vicinity of the surface of the medium is filled with a liquid with improved image fastness that has a higher viscosity than the inside, it is possible to more reliably prevent gas and water from entering the surface. It is not only excellent in properties but also excellent after long-term storage.

  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 comes into contact with the image fastness improving liquid in the pores (voids) in the ink receiving layer, starts to dissolve, and thickens the image fastness improving liquid. From the very local point of view inside the pores (voids), when this thickening is captured, it causes a much larger thickening compared to the thickening measured in the bulk. As an effect of local dramatic increase in viscosity, it is considered that the movement of the image fastness-improving liquid in the ink receiving layer during long-term storage is extremely efficiently suppressed in the present invention.

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.
1) First Embodiment As a first embodiment, a so-called uniform density distribution in which no density distribution is provided in the depth direction of the additive contained in the ink receiving layer of the recording medium used in the present invention. This will be described below as the first embodiment. 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. As the manufacturing method, when paper is used as a base material, there are roughly three forms shown in FIGS. FIG. 8 includes a water coating process before forming the ink receiving layer, an ink receiving layer forming process, and a coloring material deterioration preventing material adding process. 9 and 10 show a method for producing a recording medium including a casting process for imparting surface glossiness, but the color material deterioration preventing material adding process may be performed either before or after casting. In view of the appearance of the recording medium after finishing, it is preferable to add a color material deterioration preventing material before casting. When resin-coated paper is used as a base material, there is a form shown in FIG. FIG. 11 includes an ink receiving layer forming step and a coloring material deterioration preventing material 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. Here, the concentration distribution of the additive is measured as follows. The cross section of the ink recording medium was subjected to line analysis by FT-IR microscopic transmission measurement, and the concentration distribution was determined from 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, recycled pulp, synthetic pulp or the like is used alone or in combination of two or more. This base paper is blended with additives such as a sizing agent, a paper strength enhancer, a filler, an antistatic agent, a fluorescent whitening agent, and a 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 applied 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, ultraviolet absorbers and the like 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 resin on the back surface, 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 necessary. 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 (3)
(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, bars are applied to 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 material that, when present together with a dye in the ink-receiving layer, protects the dye from factors such as gas and light that degrade the dye 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 material 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 of adding the color material deterioration preventing material to the recording medium, the color material deterioration preventing material is a color material deterioration preventing material 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 material is easily 0.5 to 30% by mass. From the viewpoint of the appearance of the recording medium after finishing, the coating method such as hindered amine is preferably a non-contact coating method with respect to the receiving layer surface, and examples thereof include a die coater, an air knife coater, and a spray, but are not particularly limited. Also, a contact-type coating method such as a roll coater, a bar coater or a gravure coater can be used.

  The preferable content of the colorant deterioration preventing material in the ink receiving layer is preferably in the range of 0.5 to 10% by mass with respect to the pigment solid content. 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 adding the colorant deterioration preventing material 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 is applied to such a recording medium, the additive uniformly added in the ink receiving layer dissolves in the image fastness improving liquid. Thus, the image fastness-improving liquid uniformly thickens. 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.

Further, considering the handling property of the recorded matter after the application of the image fastness improving liquid and the long-term retention of the image fastness improving liquid in the ink receiving layer, at least the pore diameter of the recording medium is Affect. That is, if the pore diameter is too small, it is difficult for the applied image fastness improving liquid to penetrate into the ink receiving layer. On the other hand, the viscosity of the dye fastness improving liquid is higher than the viscosity of the dye ink necessary for image formation, which is 1.0 mPa · s to 10.0 mPa · s. Accordingly, the range is slightly narrower than the range of the pore diameter for satisfying the absorbency and color of the ink receiving layer for absorbing the dye ink. On the other hand, if the pore diameter is too large, the applied image fastness improving liquid cannot be retained in the ink receiving layer, and when the substrate is paper, the image fastness improving liquid is transferred toward the base paper. In the case where the back of the liquid occurs or the substrate is a resin-coated paper, the surface of the recorded material becomes wet with the image fastness improving liquid, and the handling property is deteriorated. As described above, the pore diameter of the recording medium is preferably in the range of 10 nm to 80 nm, and more preferably in the range of 10 nm to 60 nm.
2) Second Embodiment In the second embodiment, the concentration distribution of the additive contained in the ink receiving layer of the recording medium used in the present invention is intentionally provided. A case where there is a concentration distribution of the additive will be described as a second embodiment. Also in the second embodiment, the substrate of the recording medium used in the present invention is not particularly limited, and a paper substrate or resin-coated paper can be used as in the first embodiment. The manufacturing method is roughly divided into three forms shown in FIGS. 12, 13 and 14 when paper is used as a base material. FIG. 12 includes a two-step surface treatment step, an ink receiving layer forming step, and a coloring material deterioration preventing material adding step. FIGS. 13 and 14 show a method for manufacturing a recording medium including a casting process for imparting surface glossiness, but the color material deterioration preventing material adding process may be performed either before or after casting. In view of the appearance of the recording medium after finishing, it is preferable to add a color material deterioration preventing material before casting. When resin-coated paper is used as a base material, there are forms shown in FIGS. FIG. 15 includes a first ink receiving layer forming step, a second ink receiving layer forming step, and a coloring material deterioration preventing material adding step. FIG. 16 includes an ink receiving layer forming step by two-layer simultaneous coating and a color material deterioration preventing material adding step. By these methods, a recording medium having a density distribution in which the additive contained in the ink receiving layer of the recording medium decreases in the depth direction can be obtained.

  The first portion of the ink receiving portion has a relatively large amount of the coloring material deterioration preventing material and the second portion of the ink receiving portion relatively less than the coloring material deterioration preventing material is uniformly distributed in the ink receiving layer. More preferably, the first part is located closer to the recording medium recording surface than the second part. When a large amount of colorant deterioration preventing material is present on the recording surface side of the ink receiving portion in the ink receiving layer as described above, when the image fastness improving liquid is applied to the recorded material, particularly near the surface of the recorded material. This improves the image fastness of the liquid. As the liquid thickens, it has the effect of blocking especially the vicinity of the surface of the recorded material in which atmospheric gases enter. Compared to when the colorant deterioration prevention material is evenly distributed. Thus, it is presumed that not only the image fastness improving effect can be sufficiently exhibited, but also the excellent image fastness improving effect is exhibited even in storage for a long period of time.

  The recording medium used in the present invention is achieved by the following manufacturing method. The ink receiving portion has an ink receiving layer containing at least a pigment for holding the colorant of the ink and a binder of the pigment, and the ink receiving layer is crosslinked as it goes from the recording surface side to the depth direction. An ink recording medium having an advanced binder layer, coated with an antioxidant on the ink receiving layer, and immediately dried to have a concentration distribution that is present on the recording surface side of the ink receiving portion. It can be manufactured easily. Although the reason for having such a concentration distribution is not clear, the present inventors presume as follows.

  When an antioxidant is applied to a recording medium having a binder layer that has been crosslinked in the depth direction from the recording surface side of the ink receiving layer, the antioxidant is stopped by the crosslinked binder as it penetrates. The ink receiving layer does not penetrate so much into the base material side and a large amount exists inside the ink receiving layer. When the solvent is dried while the coloring material deterioration preventing material is not permeated, the antioxidant is pulled up with the evaporated solvent and gathers on the recording surface side. Therefore, it seems that the density distribution which exists abundantly on the recording surface side of the ink receiving layer can be provided. Therefore, the following two points play an important role in producing such a concentration distribution. The first point is to suppress the penetration of the colorant deterioration preventing material by controlling it by crosslinking of the binder, and the other point is that the colorant deterioration preventing material does not fully penetrate after coating the colorant deterioration preventing material. It is to move to a drying process within only a short time.

  As the substrate of the recording medium used in the present invention, the same thing as shown in the first embodiment can be said. The same can be said for the undercoat layer as shown in the first embodiment. Furthermore, in the first and second surface treatment steps described below, evaporation of water and solvent components from the back surface of the substrate in the casting step. In consideration of the coating property (wetting property) of the coating liquid applied to the substrate and the coating property of the ink receiving layer forming material formed on the substrate, the air permeability of the substrate (JIS P) 8117) is preferably 1,500 to 5,000 seconds. When the air permeability is less than the above range, since the denseness of the base material is low, the crosslinking agent (boric acid or borate in the coating liquid) in the first and second surface treatment steps described below. There are cases where the penetration is high and not all of the cross-linking agents work effectively. Alternatively, a larger application amount is required. Also, in the second surface treatment step, it is preferable that the coating state penetrates without overflowing, but it is difficult to adjust the coating amount, and stable coating over time in the entire CD / MD direction is difficult. It becomes.

On the other hand, when the air permeability of the substrate exceeds the above range, the permeability of the coating liquid to be applied in the first and second surface treatment steps described later is low, and the coating liquid for the ink receiving layer is further added thereto. When the ink receiving layer is applied, the ink receiving layer coating liquid may float due to overflow of the coating liquid used for the second surface treatment, or a slight crack may be formed in the formed ink receiving layer. Furthermore, during casting, water and solvent components from the back surface of the substrate are less likely to evaporate, and a good glossy surface may not be obtained. For the same reason, it is preferable that the base material has a Steecht size of 100 to 400 seconds and a Beck smoothness of 100 to 500 seconds. In addition, in order to obtain a recording medium having the same texture and high quality as a silver salt photograph, the basis weight of the base material is 160 to 230 g / m ² , and the Gurley stiffness (J. Tappi No. 40, vertical mesh) is 7 to It is preferable to be 15 mN.

  Subsequently, the types of pigments, binders, boric acid and borates, which are the materials for forming the ink receiving layer used in the present invention, are the same as those shown in the first embodiment. The same can be said for the ink-receiving layer, the coating of each coating liquid in the surface treatment step, and the drying after the coating, as shown in the first embodiment.

  As a step of controlling the crosslinking of the binder in the recording medium that can be used in the present invention, first and second surface treatments may be performed stepwise on the substrate. Hereinafter, the first and second surface treatments will be described in detail.

Coating solution used in the first surface treatment step, for example, preferably so as to be 0.05 g / m ² or more 2.0 g / m ² or less of the dry coating amount in borax solid basis. In addition, when the above range is not satisfied, the viscosity of the coating liquid is too low, and the liquid flow is large. In some cases, a uniform and good glossy surface cannot be obtained. In the first surface treatment step, a coating liquid containing at least one selected from the group consisting of boric acid and borate, for example, a 5% by mass aqueous solution of borax is applied on the undercoat layer and then dried. And solidify. You may make the said coating liquid contain solvents, such as alcohol, for a defoaming as needed. Since it is preferable to reduce the amount of dry coating in the first surface treatment step, the coating and drying speed can be considerably increased, for example, high-speed processing at 50 to 200 m per minute is possible. .

  In the second surface treatment step performed after the first surface treatment step described above, the surface treatment-treated substrate subjected to the first surface treatment step is further applied in the same manner as in the case of the first surface treatment. Then, a coating solution containing at least one selected from the group consisting of boric acid and borate is applied. In the second surface treatment, unlike the case of the first surface treatment step, the coating liquid is not dried and solidified after coating. That is, the surface of the substrate forms a certain amount of wet state (coating liquid state or thickened state may be used), and while maintaining this state, the coating liquid for forming the next ink receiving layer is applied. Is done. Here, the reaction state by the liquid-liquid interface of the present invention is ensured. That is, at this interface, the gelation rate or the crosslinking rate of the ink receiving layer coating solution is increased. On the other hand, if the reaction at the liquid-liquid interface cannot be obtained, the binder diffuses into the pores of the solidified surface by the base material or the first surface treatment, and the amount and position of the pigment to be originally changed are changed. It becomes a problem.

  The stepwise surface treatment has the following advantages. Since the coating solution is dried in the first surface treatment step performed on the substrate, boric acid or borate (hereinafter referred to as borate, etc.) is formed on the substrate or in the undercoat layer (upper part of the layer). Will exist as a solid. Then, when the next second surface treatment and the formation of the ink receiving layer are performed in this state, boric acid or an aqueous borate solution (hereinafter referred to as a borate treatment liquid or the like) applied in the second surface treatment step. In particular, there is an advantage that the borate treatment liquid or the like can reliably ensure a liquid surface. Accordingly, it is also ensured that the ink-receiving layer coating liquid in the next step and the borate treatment liquid and the like applied in the second surface treatment step are mixed in a liquid-liquid state.

  In contrast, when the ink receiving layer coating solution and a solid such as borate are in contact with each other, the solid such as borate is dissolved in the ink receiving layer coating solution although it takes time. Inside, the binder penetrates into the base material from this liquid and forms a quantitatively insufficient portion. At the same time, the coating solution in which the borate and the like are dissolved has a considerably high concentration compared to the surroundings, so that partial gelation or crosslinking proceeds rapidly, and the viscosity of the coating solution partially increases. , Because it forms a state of “coating unevenness” both inside and on the surface, there is a coexistence of an unnecessary huge pigment aggregation state (due to insufficient binder) and a binder binding state. Are very scattered.

  By adopting the surface treatment consisting of these two steps, the wet state can be formed more stably with the borate treatment liquid or the like on the surface of the substrate on which a solid such as borate is present. On the undercoat layer in this state, a rapid cross-linking reaction can be obtained at the interface due to the liquid-liquid contact, and pores between the pores formed with a solvent such as water in the coating liquid forming the ink receiving layer Can be removed while being separated from the binder, so that ideal aggregation of the pigment and proper binding due to the presence of the binder can be formed in a uniform state. As a result, the occurrence of cracks due to insufficient binder during production is suppressed, and a thick ink-receiving layer with a large amount of dry coating can be formed.

  The boric acid and borate used in the second surface treatment step can be the same as those used in the formation of the ink receiving layer or in the first surface treatment step. Use borax in terms of gelation speed or crosslinking speed in the receiving layer formation stage, viscosity change of the ink receiving layer coating liquid generated during use, and the effect of suppressing the occurrence of cracks in the formed ink receiving layer. Is preferred. In the second surface treatment step, it is preferable to set the coating amount to such an extent that the coating liquid does not overflow just on the first surface-treated substrate. Depending on the absorbency of the first surface-treated substrate, if there is a lot of overflow of the coating solution for the second surface treatment, the coating solution for the ink-receiving layer is applied when the coating solution for the ink-receiving layer is applied. However, there is a risk of floating due to overflow of the coating liquid used in the second surface treatment, and the adhesiveness of the ink receiving layer to the substrate may be lowered.

Furthermore, in the second surface treatment step, 1 selected from the group consisting of boric acid and borate so as to obtain a dry coating amount of 0.05 to 2.0 g / m ^{2 in} terms of borax solid content. It is preferable to adjust the solid content concentration of seeds or more. In the second surface treatment step, a coating solution containing at least one selected from the group consisting of boric acid and borate, for example, a 5% aqueous solution of borax is used, and this is subjected to the first surface treatment. Coat on the undercoat layer. You may make the said coating liquid contain solvents, such as alcohol, for a defoaming as needed.

Furthermore, the dry coating amount of the coating liquid applied in the first and second surface treatment steps can be appropriately determined from the relationship between the first and second surface treatments. For example, when reducing the coating amount in the first surface treatment step, it can be compensated by increasing the coating amount in the second surface treatment step, but it is easy to control the coating amount. In consideration of the relationship with the coating amount in the second surface treatment step to be performed next, the dry coating amount in the first surface treatment step is 0.1 to 1.0 g / m ^2. In consideration of the relationship between the coating speed and the coating amount in the first surface treatment, the dry coating amount of the coating liquid in the second surface treatment step is 0.3 to 1.5 g / m. ² is preferable. The wet surface is not a uniform surface but has a recess for the coating liquid, and by causing cross-linking of the binder in the recess, the adhesion of the ink receiving layer to the substrate and the anchor effect can be ensured. This is a configuration having a crosslinked binder in the concave portion, but is also an effective configuration for the formed recording medium. In the preparation of the ink receiving layer coating liquid, at least one selected from the group consisting of boric acid and borate is mixed with an alumina hydrate dispersion, and the resulting liquid mixture and a binder. It is preferable to use a mixing apparatus in which a polyvinyl alcohol aqueous solution is mixed immediately before coating to form a coating liquid. By doing so, it is possible to reduce the time-dependent increase in the viscosity of the coating solution and the gelation that occur during the production process, so that the production efficiency can be improved. The solid content concentration of the pigment in the alumina hydrate dispersion used above is preferably 10 to 30% by mass. When the above range is exceeded, the viscosity of the pigment dispersion increases and the viscosity of the ink receiving layer also increases, which may cause problems in coating properties.

  Next, it can be said that the additive in the present invention, the addition method, and the addition amount are the same as those shown in the first embodiment. The same can be said for the cast after the additive has been added to the ink receiving layer as described above, as shown in the first embodiment. The same can be said for the formation of the back surface layer of the base material as shown in the first embodiment.

  The additive contained in the ink receiving layer of the recording medium produced by the above process using the material as described above has a concentration distribution that decreases in the depth direction. When an image fastness improving liquid is applied to such a recording medium, the additive added with a concentration distribution in the ink receiving layer dissolves in the image fastness improving liquid. Along with this, the image fastness improving liquid thickens. In addition, in proportion to the concentration distribution of the additive, the vicinity of the surface of the recording material having a high concentration is thickened more than the inside having a low concentration. As a result, compared to the case where the additive is added with a uniform concentration distribution, not only can the gas infiltrate from the surface of the recorded material be stronger, but also in long-term storage. It exhibits stronger gas resistance.

  In the second embodiment, as in the first embodiment, the handling property of the recorded matter after the application of the image fastness-improving liquid and the long-term application of the image fastness-improving liquid into the ink-receiving layer Considering retention, at least the pore diameter of the recording medium has an effect, so the pore diameter of the recording medium is preferably in the range of 10 nm to 80 nm, and more preferably in the range of 10 nm to 60 nm.

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 the additive colorant deterioration preventing material 1003 added in the ink receiving layer dissolves in the image fastness improving liquid, and thus the viscosity of the image fastness improving liquid increases. is there. 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.

  According to a further preferred aspect of the present invention, as shown in FIG. 2, the additive 1003 has a presence distribution that decreases in the depth direction of the ink receiving layer 1002. Since the additive 1003 is most densely distributed near the surface of the recording medium, the vicinity of the surface of the recording medium is filled with an image fastness improving liquid having a higher viscosity than the inside. In other words, compared with the case where the viscosity is increased uniformly on the inside and on the surface, the vicinity of the surface is thickened with a higher viscosity, which can more securely prevent gas from entering the surface, and the ink receiving layer. Therefore, it is possible to further suppress the movement of the liquid for improving image fastness from the paper to the base paper. As a result, not only the initial gas resistance, glossiness, and image density are excellent, but the performance is maintained at a superior level even after long-term storage.

  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. To the base paper, or the residual ink solvent moves or evaporates, so that a gap is generated and the image fastness improving liquid is not filled. 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 method for applying the image fastness improving liquid according to the present invention will be described in detail.

(1) Example of First Embodiment As one embodiment of the recorded matter or the image fastness improving method according to the present invention, a porous layer is provided, and an image is formed by applying ink or ink droplets to the porous layer. A method of supplying and impregnating the above-mentioned image fastness improving liquid onto the surface of the porous layer of the recorded recording sheet can be mentioned. This can more reliably suppress the color material in the ink receiving layer from being attacked by a gas such as ozone. Further, the glossiness is improved and the image density is improved. And the method of the coating method is roughly divided into two types, and one is a quantitative coating method. In other words, the fixed amount is a coating method in which an appropriate amount of the image fastness improving liquid can be supplied constantly. 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 method is not particularly limited, and includes roller application, brush application, spray application, spatula application, sponge application, and the like. The other is an overcoating scraping method. This is an application method in which after an excessive application of the image fastness-improving liquid, it is scraped off so as not to damage the porous layer surface. The coating method is not particularly limited, and there are roller coating, brush coating, spray coating, spatula coating, sponge coating, etc., and the subsequent scraping method is not particularly limited, and scrapes with a blade, spatula, support plate, etc. It is.

  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.

(2) Second Embodiment Example As another embodiment of the recorded matter or image fastness improving method according to the present invention, a porous layer is provided, and an image is formed by applying ink or ink droplets to the porous layer. An example is a method in which an image fastness-improving liquid is transferred and applied to the surface of the porous layer of a recorded recording sheet using a transfer device. This can more reliably suppress the color material in the ink receiving layer from being attacked by a gas such as ozone. Further, the glossiness is improved and the image density is improved.

  The fluid transfer device according to the second embodiment stores a liquid for improving the robustness of an image of a recorded matter and transfers the liquid to the recording surface of the recorded matter, and holds the periphery of the liquid storing portion. And a holding member. In 2nd Embodiment, it is comprised by the several layer (here 2 layers) from which liquid holding force (capillary force) differs. An example is shown in FIG. FIG. 3A is a view showing a state where the lid body 8 is opened, and FIG. 3B is a cross-sectional view thereof. The lid 8 is made of a flexible material, and changes to a shape corresponding to the arrangement surface of the porous membrane 25 and the like with the lid closed as shown in FIG. Can cover this. The relationship in assembling the main members is shown as a development view in FIG. Further, an outline of the operation in using the apparatus is shown in FIG.

  As shown in FIG. 3B, the liquid storage member 24 in the second embodiment includes a first layer 24a made of a sheet-like member having a relatively low density (0.065 g / cc), and the first layer 24a. The second layer 24b is made of a sheet-like member that is polymerized on the surface (upper surface) of the layer 24a and has a relatively high density (0.2 g / cc), and the first layer 24a has a thickness greater than that of the second layer 24b. It is thick and has a large flat area. Here, the dimension of the first layer (length × width × thickness) was 178 mm × 130 mm × 4.0 mm, and the dimension of the second layer (length × width × thickness) was 158 mm × 106 mm × 1.5 mm.

  Further, the surface (upper surface) of the liquid storage member 24 is covered with a porous film 25, and the liquid transfer member 22 is configured by the porous film 25 and the liquid storage member 24. The porous film 25 is formed of sponge or the like, and the peripheral edge thereof is fixed to the bottom surface (lower surface) of the rectangular surface support frame 6 constituting a part of the housing member 13 with an adhesive. On the other hand, the accommodating member 13 that accommodates the liquid transfer member 22 is fixed with a contact plate 27 having a predetermined thickness (1.5 mm) along one side of the surface support frame 6. Further, a surface support frame 6, a housing member 7, a lid body 8, a connecting member 9, and the like are provided, and the liquid transfer member 22 is held so as not to fall off by a housing member 13 composed of these members. However, in the second embodiment, the second layer 24 b covered with the porous film 25 is fitted into the opening of the surface support frame 6, and the upper surface protrudes upward from the surface of the surface support frame 6. . Since the recorded material PM is placed on the surface of the porous film 25 protruding upward (see FIG. 5A), positioning and the like when placing the recorded material are facilitated. The contact plate 27 is preferably provided. The contact plate 27 is formed with a concave portion 27a for facilitating removal of the recorded matter.

Also in the liquid transfer apparatus according to the second embodiment configured as described above, an appropriate amount of liquid can be transferred to a recorded matter with a very simple operation. That is, the lid 8 is opened to expose the porous film 25, and the recording material receiving surface is placed on the porous film 25 holding the liquid. Next, the lid body 8 is closed, pressed several times with a spatula S from above the lid body 8, the lid body 8 is opened again, and the recorded matter is peeled off (see FIG. 5D). In the above liquid transfer process, when a pressing force is applied by the spatula S, the first layer 24a having a low density is greatly elastically deformed compared to the second layer 24b, and the liquid held inside by the elastic deformation is compared. Exuded to a large amount on the surface side (upward). The liquid that has exuded from the second layer 24b is sucked by the second layer 24b having a larger liquid holding force (capillary force) than the first layer 24a, and the sucked liquid is further liquid by the second layer 24b. It is sent to the porous membrane 25 having a high holding power. Since the porous film 25 limits the amount of liquid oozed from the lower side to the outside, an appropriate amount of liquid can be transferred to the receiving layer of the recording medium. As described above, in the second embodiment, the first layer 24a having a lower density than the second layer 24b (easily crushed and having a low liquid holding force) is provided. Since the liquid can be fed to the side 25, the liquid can be supplied without applying a strong pressing force with the spatula S. In other words, even when the remaining amount in the liquid storage member 24 becomes small, smooth liquid transfer can be realized because the first layer 24a is easily elastically deformed. Further, since the first layer 24a is easily elastically deformed, even if the recorded product PM is bent or uneven in shape, the porous film 25 is more smoothly contacted with the porous film 25 along the surface of the recorded product PM. In addition, more reliable and uniform liquid transfer can be performed.

  In the second embodiment, the liquid storage member 24 is formed by superposing two sheet-like members having different densities. However, the liquid storage member 24 is configured with different densities in the thickness direction. Is also possible by using a single member. For example, a change in density can be formed in a single member by heating while compressing one surface (for example, the surface) side of the member having a constant density. In this case, depending on how the pressure is applied, it is possible to give different densities in the upper and lower two stages, or to give a density gradient in which the density gradually changes from the front surface side to the back surface side. In this case as well, the same effect as in the case where different members are polymerized can be obtained as in the second embodiment.

(3) Third Embodiment Example As another embodiment of the image fastness improving method according to the present invention, a method of processing without manual intervention in the recording apparatus can also be mentioned. FIG. 6 is a schematic cross-sectional view of an apparatus for obtaining a recorded matter having excellent image fastness, and performs recording of an image on a recording medium by an inkjet method and processing for imparting fastness to the formed image. Each means is provided. In FIG. 6, reference numeral 25 denotes a casing, and reference numeral 1 denotes a stacked unused recording medium, which is placed substantially horizontally on a supply tray (paper feeding cassette) 2.

  Reference numeral 3 denotes a suction cup, which is moved from the position a in the drawing to a position b in contact with the uppermost one of the unused recording sheets 1 by a suction cup moving mechanism (not shown), and sucks the uppermost sheet. Can be lifted. At this time, a suction mechanism (not shown) reduces the pressure inside the suction cup 3 while the suction cup 3 is in contact with the recording paper, and adsorbs the uppermost sheet of the recording paper 1 to remove the recording paper from the other. Separate the recording paper. In this state, the suction cup moving mechanism moves to the position c in the figure, and the leading edge of the separated recording sheet can be inserted between the conveying rollers 4 and 5. Thereafter, the suction operation by the suction mechanism is stopped, the suction force of the suction cup 3 is released, and the restraint of the recording paper by the suction cup 3 can be released.

  The transport rollers 4 and 5 are rotationally driven by a drive source such as a transport motor (not shown) via a clutch mechanism (not shown). Reference numerals 6 and 7 are guide plates which are arranged to face each other with a predetermined interval, and form a supply path for recording paper to be conveyed by the rotation of the conveying rollers 4 and 5. The cross-sectional shape of the supply path formed by the guide plates 6 and 7 is substantially semicircular, and extends from the vicinity of the conveying rollers 4 and 5 to the upper sub-scanning rollers 8 and 9. These sub-scanning rollers 8 and 9, together with a second sub-scanning roller pair 10 and 11 arranged in parallel in the left direction in the figure, sandwich the conveyed recording paper, and will be described later with a control unit (not shown). ) And so on. A guide plate 15 regulates the position of the recording paper between the sub-scanning rollers 8, 9, 10, and 11. A recording head (inkjet head) 12 has a plurality of ink ejection nozzles arranged in the conveyance direction of the recording paper 1. Note that the recording head 12 may include a plurality of inkjet heads that discharge inks of different colors. An ink tank 13 stores ink to be supplied to the recording head 12. The recording head 12 and the ink tank 13 are mounted on a carriage, and can be moved in a direction substantially orthogonal to the recording paper conveyance direction by a carriage guide disposed substantially parallel to the rotation axis of the sub-scanning rollers 8 to 11. Is held in.

  Reference numeral 16 denotes an unused second recording paper stored in a stacked manner in the upper recording paper storage unit. Reference numeral 17 denotes a pressure plate on which the stacked recording paper 16 is placed and appropriately pressed in the direction of the separation roller 18. Reference numerals 19 and 20 denote guide plates, which form a second supply path for guiding the leading edge of one recording sheet taken out by the separation roller 18 to the sub-scanning rollers 8 and 9.

  21, 22, 23, and 24 are means for detecting the presence and the quality of each recording paper 1 and 16 disclosed in, for example, JP-A-1-264879. 21 and 23 are light sources for irradiating the surfaces of the recording papers 1 and 16 with light of a predetermined wavelength, and 22 and 24 are photodetectors for receiving the light reflected from the surface of the recording papers. is there.

  Such detection of the quality of the recording paper by reflected light is caused by the fact that the roughness of the surface differs depending on the type of recording paper, and the degree of light diffusion varies accordingly. . For example, when the surface of plain paper is viewed microscopically, the fibers are intertwined and the diffusion of the surface is large, so the outputs of the detectors 22 and 24 are small. On the other hand, in the case of a sheet having a smooth surface and a low degree of light diffusion, the outputs of the detectors 22 and 24 become large. Whether the recording paper corresponding to the first separation mechanism using the suction cup 3 or the second separation mechanism using the separation roller 18 is loaded in the corresponding cassette by using such light detection means. It is possible to determine whether or not a recording sheet suitable for recording is loaded.

  Reference numerals 26 and 27 denote guide plates that form a conveyance path for guiding the recording paper discharged along with the rotation of the sub-scanning rollers 10 and 11 after the recording by the recording head 12 is completed. A planar heater (not shown) is attached to the guide plate, and heats the recording paper in the conveyance path formed by the guide plates 26 and 27 to accelerate the drying of the ink ejected on the recording paper. .

  An image fastness improving liquid is supplied to the recording surface of the recorded matter thus obtained, and an area filled with the image fastness improving liquid is formed in the porous layer of the recorded matter.

  The liquid 52 is an image fastness improving liquid according to the present invention, and is supplied to the container 51 from a tank (not shown) by a supply device (not shown), and the liquid level in the container 51 is always within a predetermined range. Is automatically supplied and controlled. An image fastness improving liquid application roller 53 has a sponge-like structure through which the image fastness improving liquid 52 can permeate, and part of the surface 53 a has an image fastness improving liquid 52 in the container 51. The liquid application roller 53 is rotated by driving a driving source (not shown), so that the image fastness improving liquid 52 can be uniformly infiltrated into the surface portion 53a. Reference numeral 54 denotes a conveyance roller for nipping and conveying the recording medium in cooperation with the application roller 53. The conveying roller 54 is separated from the application roller 53 when the recording medium is not sandwiched so that the image fastness improving liquid 52 does not adhere to the surface of the conveying roller 54 and the recording medium is interposed. It is desirable that only the coating roller 53 and the conveying roller 54 are in contact with each other to sandwich the recording medium. A drying heater 55 is used to dry the recording paper coated with the image fastness improving liquid 52.

  With the above configuration, after the recording by the recording head 12 is completed, before the trailing edge of the recording sheet is separated from the second sub-scanning roller pair 10, 11, the leading edge of the recording medium is the conveying roller 54 and the coating roller 53. To reach the position. The recording medium is sandwiched between the conveying roller 54 and the application roller 53, and the image fastness improving liquid 52 is uniformly supplied to one surface of the recording medium as the rollers 53 and 54 rotate. The gap between the porous layers is filled. The recording paper filled with the liquid is subjected to a finishing process (not shown) as needed, that is, a process of scraping off an excessive image fastness improving liquid, and the paper discharge roller 33 rotates to discharge from the 34 discharge port. It is discharged out of the device.

  In FIG. 6, the image recording apparatus in which the ink jet recording and the filling of the image fastness improving liquid are processed in the same apparatus has been described. However, the present invention is not limited to this, and the image recording unit and the image fastness are not limited thereto. An image recording apparatus having a configuration in which the enhancement liquid filling section is separated, and an image robustness improving liquid coating apparatus in which the image robustness enhancement liquid filling section is independent of the image forming section are also disclosed in the present invention. It is within the range.

  Furthermore, as shown in FIG. 7, a device for applying the liquid 1 through an image between the two sets of rollers 3 and 5 can also be used. 4 is a spatula for adjusting the amount of liquid by the application roller 5, and 2 is a spatula as a means for leveling the application surface.

Hereinafter, the present invention will be further described 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>
As the image fastness improving liquid, the following five types A to E were used.
{Image fastness improving liquid A}
Product name: ODO (Nisshin Oilio Co., Ltd.)
Compound name: Capryl / Capric acid triglyceride Molecular weight: 491, Viscosity: 22 mPa · s / 25 ° C.

{Image fastness improving liquid B}
Product Name: Saracos 6318 (Nisshin Oilio Co., Ltd.)
Compound name: Trimethylolpropane triisostearate Molecular weight: 934, Viscosity: 180 mPa · s / 25 ° C

{Image fastness improving liquid C}
Product Name: Saracos 5408 (Nisshin Oilio Co., Ltd.)
Compound name: Tetra-2-ethylhexanoic acid pentaerythritol molecular weight: 641, viscosity: 60 mPa · s / 25 ° C

{Image fastness improving liquid D}
Product name: Cosmall 42 (Nisshin Oilio Co., Ltd.)
Compound name: Polyglyceryl diisostearate Molecular weight: 699, Viscosity: 625 mPa · s / 25 ° C.

{Image fastness improving liquid E}
Product name: Saracos 99 (Nisshin Oilio Co., Ltd.)
Compound name: isononyl isononanoate Molecular weight: 284, Viscosity: 5.5 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

Additive A was soluble in the image fastness improving liquids A to E at 25 ° C.
{Additive B}
Product name: ADK STAB LA-77 (Asahi Denka Kogyo Co., Ltd.)
Molecular weight: 481

Additive B was soluble in image fastness improving liquids A, 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

Additive C was soluble in image fastness improving liquids A to E at 25 ° C.
<Example of recording medium production>
{Recording medium A}
First, the base material was produced as follows. Cationic starch 0.60 was added to a pulp slurry consisting of 80 parts by mass of hardwood bleached kraft pulp (LBKP) with a freeness of 450 ml CSF (Canadian Standarad Freeness) and 20 parts by mass of softwood bleached kraft pulp (NBKP) with a freeness of 480 ml CSF. 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. After that, impregnated with an oxidized starch aqueous solution to a solid content of 1.0 g / m ² with a size press machine, dried and machine calendered, basis weight 155 g / m ² , Steecht size 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, an undercoat layer was formed on the substrate obtained above as follows. First, as a coating liquid used for forming the undercoat layer, 100 parts by mass of kaolin (Ultra White 90, manufactured by Engelhard) / zinc oxide / aluminum hydroxide having a weight ratio of 65/10/25, and commercially available 7 parts by mass of a commercially available styrene-butadiene latex was added to a slurry having a solid content of 70% by mass comprising 0.1 part by mass of a polyacrylic acid-based dispersant and adjusted so as to have a solid content of 60% by mass. To obtain a composition. Next, this composition was coated on both sides of the substrate with a blade coater so that the dry coating amount was 15 g / m ² and dried. After that, machine calender finishing (linear pressure 150 kgf / cm), basis weight 185 g / m ² , Steecht size degree 300 seconds, air permeability 3,000 seconds, Beck smoothness 200 seconds, Gurley stiffness 11.5 mN undercoat A layered substrate was obtained. The whiteness of the base material with the undercoat layer was measured for each of the five A4 size samples cut and obtained as an average value. As a result, L ^* : 95, a ^* : 0, b ^* : -2 (determined as the hue of JIS Z 8729).

The undercoat layer obtained above was subjected to surface treatment comprising the following first and second steps. First, in the first surface treatment step, a 5% by mass borax aqueous solution heated to 30 ° C. was used as a coating solution, and the coating solution was dried with a gravure coater in an amount of 0.4 g / m ^2. Was applied onto the undercoat layer at a rate of 60 m / m / min. And the coating liquid was dried and solidified at 60 degreeC. Next, in the second surface treatment step, a 5% borax aqueous solution heated to 30 ° C. similar to that used in the first surface treatment step was used, and the coating solution was wetted with an air knife coater. The coating amount was 10 g / m ² (the coating amount when dried was 0.5 g / m ² ) at 30 m / min. When this amount of coating was observed with the naked eye, the coating solution applied in the second surface treatment step did not overflow on the undercoat layer and was just impregnated.

  Next, an ink receiving layer was formed. After coating in the second surface treatment step, that is, as soon as the coating solution was impregnated in the undercoat layer, the ink receiving layer was formed on the undercoat layer as it was. did. 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. While maintaining this temperature, the pH value was adjusted to 10 with caustic soda and stirred for 10 hours. Thereafter, 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 , the pore volume was 0.8 cm ³ / g, and it was flat when observed with an electron microscope.

On the other hand, polyvinyl alcohol JM-23 (manufactured by Nippon Vinegar Bipovar 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: 8 using a static mixer. Immediately after mixing, this was used as a coating solution for the ink receiving layer, and this was coated with 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 surface layer was formed as follows on the undercoat layer on the surface opposite to the surface on which the ink receiving layer of the base material was provided. 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 so that the dry coating amount was 23 g / m ² with a die coater. And it dried at 170 degreeC and formed the back layer.

Here, the amount of boron “B” contained in the first layer region is 2.61 × 10 ⁻³ mol / m ² , and the second layer region is 9.94 × 10 ⁻³ mol / m ² . The amount of boron “B” contained in the two-layer region is 3.8 times the amount of boron “B” contained in the first-layer region. The amount of boron “B” contained in the first layer region was calculated from the following equation.
(Ink-receiving layer dry coating amount: 35) × (boric acid amount: 22.5 × 0.5%) / {(boric acid amount: 22.5 × 0.5%) + (PVA amount: 22.5 × 8/100) + (alumina hydration Quantity: 22.5)} = 0.16 g / m ²
0.16 / (Boric acid 1 mol molecular weight: 61.8) = 2.61 × 10 ^-3 mol / m ²
Further, the amount of boron “B” contained in the second layer region was calculated from the following equation.
{(Dry coating amount of second surface treatment: 0.5) / (1 mol of borax molecular weight: 201.2)} × (number of moles of B per mol of borax: 4) = 9.94 × 10 ⁻³ mol / m ²
Here, the 1 mol molecular weight of borax was calculated as Na ₂ B ₄ O ₇ since borax was not impregnated into the undercoat layer, that is, not dried.

Next, a 5% MIBK (methyl isobutyl ketone) solution of hindered amine compound ADK STAB LA-63P (Asahi Denka Kogyo Co., Ltd.) is applied to the provided ink receiving layer with a roll coater, and the excess amount is scraped off with a Mayer bar. Was 1.3 g / m ^2, that is, applied at 60 m / min so as to be 4% by mass with respect to the pigment solid content. Then, the target recording medium A was obtained by drying at 110 ° C. within 5 seconds after coating.

  The concentration distribution of the hindered amine in the obtained recording medium A was measured using the following method. A cross section of a recording medium for ink was prepared using a microtome and subjected to measurement.

The line analysis of the FT-IR microscopic transmission measurement was performed under the following conditions.
Measuring device: Spectrum One (manufactured by perkin-elmer)
Aperture diameter 98 × 14μm square line analysis conditions: 120scan / 1step 1μm / 1step
Measurement wavelength: 1730 cm ⁻¹ (IR was measured before and after addition of hindered amine, and absorption due to hindered amine that was not observed before addition was observed. See FIG. 17)
FIG. 17 shows the absorbance change of the obtained hindered amine compound in the depth direction of the ink receiving layer. Since the change in absorbance is proportional to the change in concentration, it was observed that the concentration decreased from the vicinity of the hindered amine concentration surface to the depth direction of the ink receiving layer. The maximum absorbance was about 1.8 times the minimum absorbance. Thus, it was found that the hindered amine compound has a concentration distribution.
{Recording medium B}
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. After that, impregnated with an oxidized starch aqueous solution to a solid content of 1.0 g / m ² with a size press machine, dried and machine calendered, basis weight 155 g / m ² , Steecht size 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, on the substrate obtained above, water is applied at 30 m / min so that the wet coating amount is 10 g / m ² with an air knife coater. 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. While maintaining this temperature, the pH value was adjusted to 10 with caustic soda and stirred for 10 hours. Thereafter, 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 , the pore volume was 0.8 cm ³ / g, and it was flat when observed with an electron microscope.

On the other hand, polyvinyl alcohol JM-23 (manufactured by Nippon Vinegar Bipovar 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: 8 using a static mixer. Immediately after mixing, this was used as a coating solution for the ink receiving layer, and this was coated with 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 so that the dry coating amount was 23 g / m ² with a die coater. And it dried at 170 degreeC, the back layer was formed, and the recording medium B was obtained.
{Recording medium C}
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 B with a roll coater, and 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. Then, the target recording medium C was obtained by drying at 110 ° C. within 5 seconds after coating.

  Further, when IR measurement was performed in the same manner as the recording medium A, it was found that the hindered amine compound was uniformly dispersed without having a concentration distribution.

{Recording medium D}
A recording medium D was obtained in the same manner as the recording medium C except that the hindered amine compound Adekastab LA-63P was replaced with Adekastab LA-77 (Asahi Denka Kogyo Co., Ltd.). Further, when IR measurement was performed in the same manner as the recording medium A, it was found that the hindered amine compound was uniformly dispersed without having a concentration distribution.
{Recording medium E}
A recording medium E was obtained in the same manner as the recording medium C except that the hindered amine compound ADK STAB LA-63P was replaced with ANTAGE BHT (manufactured by Kawaguchi Chemical Co., Ltd.). Further, when IR measurement was performed in the same manner as the recording medium A, it was found that the hindered amine compound was uniformly dispersed without having a concentration distribution.
{Recording medium F}
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: 8 using a static mixer. Immediately after mixing, this was used as a coating solution for the ink receiving layer, and this was coated with 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 F was obtained.

{Recording medium G}
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 F with a roll coater, and 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 G was obtained.

Further, when IR measurement was performed in the same manner as the recording medium A, it was found that the hindered amine compound was uniformly dispersed without having a concentration distribution.
{Recording medium H}
A recording medium H was obtained in the same manner as the recording medium G except that the hindered amine compound Adekastab LA-63P was replaced with Adekastab LA-77 (Asahi Denka Kogyo Co., Ltd.). Further, when IR measurement was performed in the same manner as the recording medium A, it was found that the hindered amine compound was uniformly dispersed without having a concentration distribution.

{Recording medium I}
A recording medium I was obtained in the same manner as the recording medium G except that the hindered amine compound ADK STAB LA-63P was replaced with ANTAGE BHT (manufactured by Kawaguchi Chemical Co., Ltd.). Further, when IR measurement was performed in the same manner as the recording medium A, it was found that the hindered amine compound was uniformly dispersed without having a concentration distribution.
<Examples 1 to 21 and Comparative Examples 1 to 17>
(Creation and evaluation of recorded materials)
A recorded matter in which an image is recorded on the recording medium created as described above is created, and an image fastness improving liquid is used for the recorded matter according to the following methods (1) to (5). Various image fastness tests were performed.

Ink-jet printer (trade name: BJ-F900 made by Canon) and genuine ink tank (trade name: BCI-6BK, BCI-6Y, M, C, BCI-6PM, BCI-6PC) On the recording surface of the recording medium obtained above, 100%, 80% for each color of black, cyan, magenta and yellow as composite colors, composite black, leaf green, skin color and sky blue as composite colors 60%, 40%, 20%, and 10% solid patches of each density were printed to produce recorded matter. Note that the ink used for printing is a genuine product of the printer, and is a water-based ink that contains a water-soluble dye. Next, 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. There are three types of coating methods. One is a rubbing member made of natural cotton, and the entire surface of the image is rubbed. The other is coated using a coating roller having the configuration shown in FIG. The coating was carried out using a transfer device. Thus, recorded materials of Examples 1 to 21 and Comparative Examples 1 to 17 were obtained. For each recorded matter, a patch having a color image density of about 1.0 was selected and used for the following tests. In Comparative Examples 9 to 17, the image fastness improving liquid is not applied.
(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;
Basically, among yellow, magenta, cyan, and composite black, the ink with the worst gas resistance is used as the gas resistance evaluation result, but here composite black is the most fading, so composite black printing The reflection density before and after the ozone exposure test in the part was measured using a spectrophotometer / spectrino (manufactured by Gretag Macbeth) and evaluated by ΔE calculated therefrom. The results are shown in Table 1.
(2) An image density BJF900 (manufactured by Canon Inc.) was used to print a 100% printed portion of 3 cm square of black, and the printed portion was measured using a spectrophotometer / spectrino (manufactured by Gretag Macbeth Co.). The results are shown in Table 1.
(3) Glossiness test A glossiness meter defined by JIS-Z-8741 (trade name: VG2000, Japan) after each recorded matter coated with the image fastness-improving liquid was stored at room temperature for 24 hours. Using Denshoku Industries Co., Ltd., the specular gloss of 20 degrees was measured for the unprinted part (white part). The results are shown in Table 1.
(4) Water resistance test A solid image of each color ink of yellow, magenta, cyan and black is printed, and the recorded matter coated with the image fastness improving liquid is stored at room temperature for 24 hours, and then the image fastness is improved on the recorded matter. 1 mL of ion-exchanged water having a water temperature of 20 ° C. was gently dropped in the vicinity of the boundary between the printed part and the non-printed part on the surface where the liquid was applied, and left as it was until it naturally dried. Among yellow, magenta, cyan and black, the ink having the lowest water resistance was used as the water resistance evaluation result. The evaluation criteria for water resistance are as follows. The results are shown in Table 1.
A: The recording agent does not flow out to the blank area, and the background is hardly seen.
◯: The recording agent flows out to the margin part and is slightly blurred, but at a level where there is no practical problem.
X: The recording agent flowed out to the marginal area, and the soiling was severe, and the bleeding was also severe.
(5) Uniform coating property Visual evaluation was performed on the uniform coating property of the image fastness improving liquid. 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.

  Further, after the recorded materials of Examples 1 to 21 and Comparative Examples 1 to 17 were stored for 90 days in a 24 ° C./60% RH environment, the light resistance, gas resistance, image density, glossiness of each recorded material, The water resistance was evaluated by the same test method and standard. The results are also shown in Table 1.

  The results of evaluation on gas resistance, image density, glossiness, water resistance, and uniform coatability are described below.

  In the initial evaluation, the ΔE value differs greatly between the system in which the image fastness improving liquid is not applied and the system in which the liquid is applied. When the image fastness improving liquid is applied, the gas resistance, image density, glossiness, and water resistance are dramatically improved. It is clear that it will improve. Further, in the system for applying the image fastness improving liquid, a recording medium which is soluble in the image fastness improving liquid and has an additive for thickening the image fastness improving liquid added to the porous layer is used. In cases (Examples 1 to 21), a recording medium to which no additive is added (Comparative Examples 1 to 4), or an additive insoluble in the image fastness improving liquid is added to the porous layer. When a recording medium is used (Comparative Examples 5 and 6), or an additive that is soluble in the image fastness improving liquid but has a molecular weight ratio L not satisfying 0.5 ≦ L ≦ 10.0 is porous When the recording media added in the layer were used (Examples 9 and 10), the image fastness-improving liquid was soluble and the molecular weight ratio L was 0.5 ≦ L ≦ 10.0. Excellent results even in the initial stage when using recording media with additives Not only are obtained, exceptional effect is obtained in particular evaluation after long-term storage. Further, the system (Examples 1, 4, 13, 16, 19) in which the image fastness improving liquid is applied to the recording medium in which the additive exists in a distribution that decreases in the depth direction of the porous layer is the most excellent. Results are shown.

  Moreover, it was confirmed that Examples 1 to 21 were all uniformly applied. This shows that the evaluation result after long-term storage is excellent, and it can be seen that the image fastness-improving liquid is continuously filled in the porous layer even for a long time. Even when the difference in the coating method was compared, the same results as the coating method with a manual pressure such as a rubbing process were obtained even in the coating method in which relatively no pressure was applied such as roller coating or transfer device.

  The results regarding thickening are shown below. Since it is difficult to capture the change in viscosity of the image fastness improving liquid impregnated in the recording medium, the change in viscosity in the bulk was observed. In the test method, 100 g of the image fastness-improving liquid was put in a beaker, and the additive was added to 10 parts and dissolved with stirring. The viscosity of the image fastness-improving liquid was measured, and the initial viscosity and This can be confirmed by comparison. As a result, when the image fastness-improving liquid A and additive A were dissolved, the initial viscosity was 22.5 mPa · s, but after dissolution, it was 37.4 mPa · s. When the image fastness-improving liquid B and additive A were dissolved, the initial viscosity was 180.0 mPa · s, but after dissolution, it was 295.0 mPa · s. Although not tested in other combinations, thickening can be confirmed by appearance, and it is surmised that the equivalent thickening is sufficiently generated from the image fastness effect.

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. In the case where the additive in the ink receiving layer has a concentration distribution in the depth direction, a cross section of the recording medium when an image fastness improving liquid is applied after recording an image on the recording medium according to the present invention Is schematically shown. It is the bird's-eye view and sectional drawing of the opening part of the transfer device for carrying out transfer application of the image fastness improvement liquid used for the image fastness improvement method concerning the present invention. It is each member expansion | deployment figure of the transfer device for carrying out transfer coating of the image fastness improvement liquid used for the image fastness improvement method concerning this invention. 3 is a schematic diagram showing a procedure for transferring and applying an image fastness improving liquid used in the image fastness improving method according to the present invention. 1 is a schematic cross-sectional view of an ink jet recording apparatus according to the present invention. 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. 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. It is a schematic process drawing which shows the manufacturing process of a recording medium. It is a figure which shows an example of the result of IR measurement.

Claims (3)

Improving image fastness by applying an image fastness-improving liquid to the ink-receiving layer on the image-formed surface after forming an image with a dye ink on a recording medium having an ink-receptive layer on at least one surface of the substrate A method,
The image fastness-improving liquid comprises caprylic / capric triglyceride, trimethylolpropane triisostearate, penta 2-ethylhexanoate as a fatty acid ester having a viscosity range at 25 ° C. of 15 mPa · s to 300 mPa · s. It is one kind selected from Erislit,
The ink receiving layer contains at least a pigment, a binder, and a colorant deterioration preventing material,
It said colorant deterioration preventing agent, the image is soluble in fastness improving liquid, and the image fastness improving following formula with the dissolution in the liquid to thicken the image fastness improving liquid (A) ~ At least one selected from compounds represented by (C) ,

The color material deterioration preventing material exists in a distribution that decreases in the depth direction of the ink receiving layer,
The molecular weight ratio L represented by the following formula (1) between the molecular weight Ma of the colorant deterioration preventing material and the molecular weight Mb of the image fastness improving liquid is in the range of 0.5 ≦ L ≦ 10.0. Image fastness improvement method.
Molecular weight ratio L = Ma / Mb (1)   2. The method for improving image fastness according to claim 1, wherein the colorant deterioration preventing material 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 improvement is obtained by holding the liquid in a dry constant temperature bath at 70 ° C. in an open state, storing it for 500 hours, transferring the sample to a desiccator, allowing to cool for 30 minutes, and measuring the weight. The method of improving image fastness according to claim 1 or 2, wherein the non-volatile rate A (%) represented by the following formula (2) of the liquid is 98.0% or more.
Nonvolatile rate A = [weight of liquid after storage (g) / weight of target liquid (g)] × 100 (2).

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