JP4029760B2 - Method for producing ink jet recording sheet - Google Patents

Description

【０１０５】
【表２】

【０１０６】
表１の各実施例のように、特定の湿式法微細シリカ、電解質及びポリビニルアルコールを含み、ｐＨが７以上の水性塗料を支持体に塗工、乾燥して多孔質インク受容層を設け、その上に光沢発現層を設けることが本発明の特徴である。水溶性塩類の効果により多孔質インク受容層中に大きな凝集構造が形成され、大きな細孔が多数存在することによって毛細管収縮力が緩和され、乾燥工程のひび割れが防止されている。その結果、表２の各実施例から明らかなように、各実施例の多孔質インク受容層は、細孔径６〜１５０ｎｍの範囲に２つのピーク、または肩を有する１つの幅広いピークを有していた。また顔料の細孔径に比べて受容層の細孔径が大きく、モード細孔径とメジアン細孔径の差の絶対値が１０ｎｍ以上であることからも分かるように大きな細孔が多数存在する幅広い細孔ピークを有していた。そのためインク吸収速度が十分に速く、インク吸収量も大きかった。さらにインクジェット記録シートの光沢度も十分に高かった。
【０１０７】
一方、比較例３〜６のように電解質を含まない水性塗料を塗工、乾燥して多孔質インク受容層を得た場合、大きな凝集構造を生じないために乾燥過程での強い毛細管収縮力を緩和することができず、受容層はひび割れを多数生じた。そのため比較例３〜５では光沢発現層を設けても光沢度は低かった。上記細孔径範囲の細孔ピークが１つのみであることからも分かるように、凝集構造を生じないために受容層の細孔径は大きくなっておらず、そのためにインク吸収速度は遅く、細孔容積も大きくなりにくいためにインク吸収量も不足していた。比較例６では大きなひび割れが多数生じ、支持体から剥がれたために光沢発現層を設けることができなかった。
【０１０８】
シリカの種類の影響について述べれば、活性珪酸を縮合させて製造された微細シリカ分散液Ｂを用いた場合にはインク受容層の細孔容積が最も高く、インク吸収量も良好である上、光沢も良好であった。この微細シリカは式１と式２を同時に満たすものであった。
（式１） 比表面積（ｍ^２／ｇ）＜７３０−６００×細孔容積（ｍｌ／ｇ）
（式２） 比表面積（ｍ^２／ｇ）＞４５０−６００×細孔容積（ｍｌ／ｇ）
比較例 1 で用いた微細シリカ分散液Ｅは、やはり活性珪酸を縮合させて製造されたシリカであるが、式１は満たさず、式２のみを満たす。この場合は、インク受容層に多少ひび割れが見られた。比較例２で用いた微細シリカ分散液Ｆは、式１を満たし、式２を満たさない例であり、インク受容層の細孔容積がやや低めであり、インク吸収量が多少低下した。
【０１０９】
【発明の効果】
本発明のインクジェット記録シートの製造方法により、微細顔料を用いた場合にしばしば問題となるひび割れによる成膜不良を生じること無く製造することができた。また、製造されたものは写真印画紙調の高い光沢を有し、高いインク吸収速度とインク吸収量を兼ね備えたものであり、銀塩写真の代替として好適なものである。
【０１１０】
【図面の簡単な説明】
【図１】本発明における多孔質インク受容層の細孔分布曲線の図。Ｖはインク受容層の細孔容積を、Ｄはインク受容層の細孔径を示す。
【図２】電解質をインク受容層に含まず、細孔径６〜１５０ｎｍの範囲にピークを１つしか持たないインク受容層の細孔分布曲線の図（本発明外）。
【図３】シリカの比表面積と細孔容積をそれぞれグラフの縦軸と横軸にとり、各シリカを塗料として基材に塗工した際の塗膜ヘイズ値を５段階に分類し、記載した。ヘイズ値は、（株）クラレ製ポリビニルアルコール１４０Hをシリカに対し２０部数混合した塗料を、基材の（株）東レ製、商品名：ルミラー１００−Q８０Dに乾燥質量が２０g /m²になるように塗工したものを、ＪＩＳ規格Ｋ７１０５に従って測定した。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording sheet.Manufacturing methodIn particular, an ink jet recording sheet that has a gloss of photographic printing paper tone, has a high ink absorption speed and an ink absorption amount, and does not crack in the ink receiving layerManufacturing methodAbout.
[0002]
[Prior art]
The ink jet recording method is a recording method suitable for personal use because color printing can be performed at a low cost with a simple apparatus, and is rapidly spreading in printing applications in offices and homes. In recent years, full color and high resolution have been achieved, and the image quality has improved rapidly. It has attracted attention as an easy-to-use output format for color images and is considered one of the most powerful alternatives to silver halide photography. Yes. Therefore, there is an increasing demand for an inkjet recording sheet having high image quality and high gloss comparable to silver salt photography.
[0003]
Since ink used in the ink jet system contains a large amount of solvent, it is necessary to eject a large amount of ink in order to obtain a high printing density. Therefore, the ink receiving layer provided on the ink jet recording sheet is required to be a material that can sufficiently absorb the ejected ink. In addition, since ink droplets are ejected continuously, if the next droplet is ejected before the first droplet is absorbed, bleeding or density unevenness is caused, and a clear image cannot be obtained. Therefore, the ink receiving layer is required to have a high absorption speed as well as an absorption amount. Furthermore, in addition to the above-mentioned requirements for image quality, various performances such as ink drying properties, water resistance of printed matter, and image storage stability in the case of long-term storage are required.
[0004]
In order to satisfy the above requirements, many inkjet recording sheets provided with a resin-based or pigment-based ink receiving layer have been proposed and are commercially available. The resin-based receiving layer is generally formed by applying an aqueous solution of a water-soluble resin such as polyvinyl alcohol, polyvinyl pyrrolidone, a water-soluble cellulose derivative, gelatin or the like to a support and drying it. The resin-based receptive layer has the advantages of high printing density and high gloss due to its high transparency. On the other hand, the ink absorption rate is slow, so the image quality is poor, and the ink drying rate is slow and the water resistance is poor. There is a drawback. For this reason, it is difficult to obtain a print quality equivalent to a silver salt photograph that has been required in recent years, and the pigment-based receiving layer described below has become mainstream recently.
[0005]
The pigment-based receiving layer is formed by adding a water-soluble resin such as polyvinyl alcohol or cellulose derivative as a binder resin to a pigment such as silica, alumina, pseudoboehmite, calcium carbonate, or kaolin. As the form of the pigment, those in which primary particles are aggregated to form secondary particles are preferably used. In such a pigment-based receiving layer, ink is quickly absorbed by capillarity between the primary particles and the secondary particles of the pigment to form an image, so that the image quality is good and the ink drying property is also good.
[0006]
In general, many commercially available pigments have a secondary particle diameter exceeding 1 μm, and when these are used in a pigment-based receiving layer, a large gap between secondary particles is formed, resulting in high ink absorbability. . However, since the secondary particle size is large, the smoothness of the surface of the receiving layer is low and the gloss is low. Therefore, it is not suitable for the purpose of obtaining high gloss of photographic printing paper tone that has been demanded in recent years. Further, since the transparency of the receiving layer is low, there is a disadvantage that the print density is low. For example, an ink receiving layer proposed in JP-A-61-47290 (Patent Document 1) containing an alkali metal weak acid salt and / or a double salt thereof has an alkali metal weak acid salt and average secondary particles. Combined use with a pigment having a diameter of 0.5 to 30 μm combined ink absorbency and water resistance and light resistance of the image, but it was necessary to use a pigment with a large secondary particle size, so gloss and print density Was low.
[0007]
In order to overcome the drawbacks as described above, many ink jet recording sheets having a pigment-based ink jet receiving layer using a fine pigment having a particle diameter of 1 μm or less have been proposed. Japanese Patent Application Laid-Open No. 9-183267 (Patent Document 2) proposes an ink receiving layer in which the uppermost layer contains colloidal silica and the pore distribution curve has a peak in the pore diameter range of 2 nm to 100 nm. When pore peaks exist in this range, the ink absorption rate is increased, and since monodispersed colloidal silica having a small particle diameter is used, the gloss is excellent and the transparency is also good. However, since colloidal silica does not form secondary particles, the pore volume of the receiving layer is low, and a large amount of coating is required to absorb a large amount of ink to be ejected. In the example of Japanese Patent Laid-Open No. 9-183267 (Patent Document 2), an example having two peaks in this range is described. This is the case when two ink receiving layers are provided. A peak that exists one by one in the layer appears. Moreover, it is not described that the ink receiving layer contains an electrolyte.
[0008]
Japanese Patent Application Laid-Open No. 2001-96897 (Patent Document 3) proposes an ink jet recording material having an ink receiving layer containing gas phase method silica and a water-soluble metal compound and having a film surface pH of 3 to 5. . Vapor phase silica is an ultrafine particle in which primary particles having an average particle size of 3 nm to 10 nm are aggregated to form secondary particles of 100 nm to 500 nm, and since it has a small particle size, it can have high gloss. Ink absorbability is high due to the space between the secondary particles. However, when such ultrafine particles having a secondary particle size of 1 μm or less are used, there is a manufacturing problem such that the pore size is small due to the small particle size, and the ink receiving layer is easily cracked in the drying process due to the strong capillary contraction force. is there. Increasing the amount of binder resin added to reduce the capillary contraction force and prevent cracking is not preferable because it causes an extreme decrease in ink absorbability. Although the above publication proposes the addition of a water-soluble metal compound, the film surface pH must be 3 to 5. In addition, gas phase method silica has a much stronger capillary shrinkage force in the drying process than wet method silica, so in addition to the above method, a binder resin is crosslinked with boric acid in order to produce a sufficiently crack-free receiving layer. The receiving layer thus formed has the disadvantage that it becomes brittle in strength and peels off under high temperature and high humidity.
[0009]
[Patent Document 1]
JP 61-47290 A (Claims)
[Patent Document 2]
JP-A-9-183267 (Claims and Table 1)
[Patent Document 3]
JP 2001-96897 A (claim)
[0010]
[Problems to be solved by the invention]
The object of the present invention is to solve the problems of the prior art, have a photographic paper-like gloss, excellent ink absorption speed and ink absorption amount, and in the ink-receiving layer manufacturing process during drying. It is an object of the present invention to provide a recording sheet for an ink jet printer that does not cause film formation defects due to cracks.
[0011]
[Means for Solving the Problems]
In general, a porous ink receiving layer having a peak in a pore diameter range of 6 nm to 150 nm in a pore distribution curve obtained by measurement with a mercury porosimeter can quickly absorb ink by its strong capillary force to obtain a clear image. . However, a porous receiving layer having a pore diameter in the above range and having only one sharp peak having a narrow width as shown in FIG. 2 is strong in the drying process after coating the ink receiving layer coating liquid. Capillary contraction force often acts to cause film formation failure due to cracking. In addition, the amount of ink absorbed is often insufficient to absorb a large amount of ejected ink instantaneously, and there is a tendency that ink overflows or print density unevenness called beading occurs.
[0012]
As a result of intensive studies by the present inventors, the porous ink receiving layer having two peaks in the pore diameter range of 6 nm to 150 nm or one broad peak having a shoulder as shown in FIG. In addition, the present inventors have found that the ink absorption speed is high and the ink absorption amount increases. And as a result of earnestly examining the method of forming the porous ink receiving layer having such a pore distribution,On the supportIn addition to fine silica and polyvinyl alcohol produced by a wet method, electrolyteDry after applying aqueous paint containing pH 7 or moreIt was found that it can be formed. Since the porous ink receiving layer has large pores, the gloss is not sufficient as it is, but by providing a gloss developing layer on the porous ink receiving layer, a high gloss can be given, and an excellent recording density, silver salt It was found that an appearance like a photograph was obtained, and the present invention was completed.
[0013]
The present invention includes the following embodiments.
[1] The average particle diameter is 0.5 μm or less on at least one side of the support.The specific surface area and pore volume by the nitrogen adsorption method satisfy (Equation 1) and (Equation 2), and the specific surface area is 150 to 300 m. ² / G and the pore volume is 0.5 to 0.9 ml / gAfter applying a water-based paint having a pH of 7 or more containing fine silica, an electrolyte, and polyvinyl alcohol produced by a wet method, a porous ink receiving layer is provided by drying, and a gloss developing layer is further provided. A method for producing an ink jet recording sheet.
(Formula 1) Specific surface area (m ² / G) <730-600 × pore volume (ml / g)
(Formula 2) Specific surface area (m ² / G)> 450-600 × pore volume (ml / g)
[2] The method for producing an ink jet recording sheet according to [1], wherein the 75 ° specular gloss (JIS P8142) is 40% or more.
[3] The method for producing an inkjet recording sheet according to [1] or [2], wherein the support is a non-permeable support.
[4] The method for producing an ink jet recording sheet according to [3], wherein the non-permeable support has a 75 ° specular gloss (JIS P8142) of 60% or more.
[5] The inkjet recording sheet according to any one of [1] to [4], wherein the fine silica is secondary particles having an average particle size of 8 nm to 500 nm formed by agglomerating primary particles having an average particle size of 3 nm to 100 nm. Manufacturing method.
[0014]
[6The fine silica is produced by condensing activated silicic acid [1] to [1]5]A method for producing an ink jet recording sheet according to any one of the above.
[7] The electrolyte is sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, SulfurCalcium acid, Sodium carbonate, sodium hydroxideThe method for producing an inkjet recording sheet according to any one of [1] to [6], which is at least one selected from the group consisting of:
[8The electrolyte is a strong alkali metal salt [7]2. A method for producing an ink jet recording sheet according to 1.
[9The content of the electrolyte is 0.05 to 5 parts by mass with respect to 100 parts by mass of the fine silica.8]A method for producing an ink jet recording sheet according to any one of the above.
[10The degree of saponification of polyvinyl alcohol is 90% or more [1] to [1]9]A method for producing an ink jet recording sheet according to any one of the above.
[11The degree of polymerization of polyvinyl alcohol is 1700 or more [1] to [10]A method for producing an ink jet recording sheet according to any one of the above.
[12The porous ink receiving layer has two peaks in a pore diameter range of 6 nm to 150 nm or one broad peak having a shoulder in a pore distribution curve measured with a mercury porosimeter [1] ~ [11]A method for producing an ink jet recording sheet according to any one of the above.
[13The absolute value of the difference between the mode pore diameter and the median pore diameter in the pore distribution curve is 10 nm or more [12]2. A method for producing an ink jet recording sheet according to 1.
[14The pore volume of the porous ink receiving layer in the pore diameter range of 6 nm to 1 μm is 0.5 to 2.0 ml / g [12]Or [13]2. A method for producing an ink jet recording sheet according to 1.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A method for forming a porous ink receiving layer in the present invention will be described. The porous ink receiving layer of the present invention has an average particle size of 0.5 μm or less.specificWet method Fine silica is produced by solidifying with polyvinyl alcohol. The formation method is not particularly limited, but in order to obtain a porous ink receiving layer that is excellent in ink absorption rate and ink absorption amount and does not cause film formation failure due to cracks during drying in the production process, The method is preferably used. It contains 1 to 100 parts by weight, preferably 3 to 28 parts by weight, more preferably 5 to 20 parts by weight of polyvinyl alcohol with respect to 100 parts by weight of fine silica, and preferably 0.01 to 10 parts of the electrolyte. Part by mass, more preferably 0.05 to 5 parts by mass, PH is 7 or moreA water-based paint is applied to a support and dried to form an ink receiving layer.
[0016]
The fine silica used in the present invention has a particle size of 0.5 μm or less and is stably dispersed in a colloidal form in the water-based paint. In the drying process, the electrolyte contained is adsorbed on the surface of the fine silica until the concentration of the water-based paint increases and is dried, so that the surface charge is reduced and the dispersion stability is lost. A large aggregate structure is produced by the action of alcohol. The voids present in this aggregated structure are distributed in the range of 6 nm to 150 nm, resulting in the formation of a porous ink receiving layer having two peaks in the pore diameter range of 6 nm to 150 nm or one broad peak with shoulders. The In this way, an aggregate structure is generated due to the influence of the electrolyte, and the capillary contraction force is alleviated by the presence of a large number of pores having a large diameter, and cracking in the drying process can be prevented after the ink receiving layer is applied. .
[0017]
The silica used in the present invention is silica that is chemically synthesized by a wet method. Silica is roughly classified into natural silica obtained by pulverizing natural silica such as quartz and synthetic silica produced by synthesis. Synthetic silica is roughly classified into wet silica and dry silica. As the wet process silica, a silica by a precipitation process and a silica by a gel process are known. In addition, although described later, silica produced by condensing active silicic acid is also included. Precipitated silica is produced, for example, by adding a mineral acid stepwise to an alkali silicate aqueous solution and filtering the precipitated silica as disclosed in JP-A-55-116613. The gel method silica is obtained by mixing a mineral acid with an alkali silicate solution, gelling, washing, and pulverizing. The precipitated silica and the gel silica are formed by combining primary particles of silica to form secondary particles, and there are many voids between the primary particles and between the secondary particles. Since it is large and has a low light scattering property, a high print density can be obtained, so that it is preferably used in the present invention.
[0018]
The dry process silica is also referred to as gas phase process silica, and is a silica produced by a method in which a volatile silicon compound is decomposed at a high temperature in a flame as disclosed in, for example, Japanese Patent Publication No. 59-169922. It is commercially available as a powder having a very low bulk density. When an aqueous dispersion of dry silica is dried, it becomes porous silica gel, and the pore volume by the nitrogen adsorption method of the gel is generally 1.2 to 1.6 ml / g, which is convenient for absorbing ink. However, cracks during drying are significant and it is not easy to produce an ink receiving layer free of cracks. Even when polyvinyl alcohol and an electrolyte are added to produce an ink receiving layer, an aggregated structure is not formed. In this respect, the wet silica is superior.
[0019]
As a slightly special production method for wet-type silica, a method for producing active silica by condensation is known. For example, in US Pat. No. 2,574,902, an aqueous solution of active silicate is prepared by treating a dilute aqueous solution of sodium silicate with a cation exchange resin to remove sodium ions. Is added to stabilize and polymerize to form a liquid in which silica seed particles are dispersed (seed liquid), and the remaining part of the active silicic acid aqueous solution (feed liquid) is gradually added to this while maintaining alkaline conditions. Thus, a method for polymerizing silicic acid to grow colloidal silica particles is disclosed. Silica produced by this method has a diameter of 3 nm to several hundred nm, has no secondary aggregation, and has a very narrow particle size distribution. Usually, a product of 7 nm to 100 nm, which is called colloidal silica, is commercially available as an aqueous dispersion, and when used for an ink receiving layer, a receiving layer having extremely high gloss and high transparency can be obtained. However, since it is not secondary particles, the precipitated silica and the gel silica are superior in terms of ink absorption.
[0020]
Silica having the advantages of precipitated silica and gel silica and colloidal silica can also be produced by condensing active silicic acid, specifically, JP-A Nos. 2001-354408 and 2002-2002. The silica currently disclosed by 145609 gazette is illustrated. This silica is a secondary particle in which the primary particles of silica are bonded, and it is easy to adjust the secondary particle diameter to be equal to or less than the wavelength of light, so that an ink receiving layer having excellent ink absorption and glossiness can be easily formed. Since it can be produced, it is most preferably used in the present invention.
Japanese Patent Application Laid-Open No. 2001-354408 includes
"Specific surface area by nitrogen adsorption method is 300m²/ G-1000m²/ G with a colloidal dispersion of silica fine particles having a pore volume of 0.4 ml / g to 2.0 ml / g as a seed solution, and after adding alkali to the seed solution, A specific surface area by a nitrogen adsorption method is 100 m, wherein silica fine particles are grown by adding small amounts of at least one feed liquid selected from an aqueous solution of active silicic acid and alkoxysilane.²/ G-400m²/ G, a method for producing a silica fine particle dispersion in which silica fine particles having an average secondary particle diameter of 20 nm to 300 nm and a pore volume of 0.5 ml / g to 2.0 ml / g are colloidally dispersed. "
[0021]
"Specific surface area by nitrogen adsorption method is 300m²/ G-1000m²/ G and a liquid in which fine silica particles having a pore volume of 0.4 ml / g to 2.0 ml / g are colloidally dispersed is used as a seed liquid, and the seed liquid is selected from an active silicic acid aqueous solution and an alkoxysilane. A specific surface area by a nitrogen adsorption method is 100 m, wherein silica fine particles are grown by adding a mixture of at least one kind of feed liquid and alkali little by little, or adding the feed liquid and alkali little by little at the same time.²/ G-400m²/ G, a method for producing a silica fine particle dispersion in which silica fine particles having an average secondary particle diameter of 20 nm to 300 nm and a pore volume of 0.5 ml / g to 2.0 ml / g are colloidally dispersed. Is described.
[0022]
Japanese Patent Application Laid-Open No. 2002-145609 discloses that a suspension containing aggregates composed of silica fine particles is formed by heating an aqueous solution containing at least one selected from activated silicic acid and alkoxysilane, and then the suspension is formed. At least one selected from an aqueous solution containing active silicic acid in the presence of alkali and alkoxysilane is added to the suspension in small portions to grow silica fine particles in the suspension, and then the suspension is wet pulverized. The manufacturing method of the silica fine particle dispersion characterized by doing. "
[0023]
As a form of fine silica, in order to obtain a highly glossy and highly transparent ink-receiving layer, the average particle diameter is 0.5 μm or less. Further, the fine silica is preferably secondary particles composed of primary particles having an average primary particle diameter of 3 nm to 100 nm, preferably 3 nm to 40 nm, since the pore volume is high. The average particle diameter of the secondary particles in which these primary particles are aggregated is 0.5 μm or less, preferably 8 nm to 499 nm, more preferably 10 nm to 400 nm, and most preferably 20 nm or more and less than 300 nm. If the primary particle size or the secondary particle size is too small, it will be difficult to form voids that contribute to ink absorption, and the pore volume of the receiving layer may decrease, leading to a decrease in ink absorbability. On the other hand, if the primary particle size or the secondary particle size is too large, the transparency of the receiving layer is lowered, and the print density and gloss may be lowered. In addition, all the primary particle diameters as used in the field of this invention are the particle diameters (Martin diameter) observed with the electron microscope (SEM and TEM). The secondary particle size is a value calculated from an analysis using a cumulant method, measured by a dynamic light scattering method.
[0024]
The specific surface area and pore volume of fine silica by the nitrogen adsorption method satisfy Equation 1.The
(Formula 1) Specific surface area (m²/ G) <730-600 × pore volume (ml / g)
Based on JP-A-2001-354408, the present inventors produce fine silica having various specific surface areas and pore volumes, and add polyvinyl alcohol as a binder to form an ink receiving layer by coating. As a result, as shown in FIG. 3, it was found that the ink receiving layer is clearly divided into a region having high transparency, that is, a low haze value, and a region having low transparency, that is, a region having a high haze value. The formula representing the boundary line between these two regions is the specific surface area (m²/ G) = 730-600 × pore volume (ml / g). A high haze value indicates that a large amount of voids having a large pore diameter are generated. When used in the ink receiving layer, the silica satisfying the formula 1 can be promoted to be aggregated by adding a slight amount of an electrolyte of 0.05 to 1 part by mass with respect to 100 parts by mass of silica, and cracking of the ink receiving layer can be prevented. The ink absorbency was also good.
[0025]
However, since the specific surface area of fine silica and the pore volume satisfying Equation 3 are slightly inferior in ink absorbency,In the present inventionSatisfy Equation 1 and Equation 2 simultaneouslyUse fine silica.
(Formula 2) Specific surface area (m²/ G)> 450-600 × pore volume (ml / g)
(Formula 3) Specific surface area (m²/ G) <450-600 × pore volume (ml / g)
[0026]
further,Fine silica simultaneously satisfies Formula 1 and Formula 2 and has a specific surface area of 150 to 300 m.²/ G and a pore volume of 0.5 to 0.9 ml / g. Silica in this range has an excellent balance of cracks in the ink receiving layer, ink absorbency, and gloss.
[0027]
There is no particular limitation on the method of converting the silica into fine silica having an average particle size of 0.5 μm or less. As one of the means, commercially available silica (having a particle size of several μm to several tens of μm) has strong mechanical strength. And a method obtained by pulverizing and dispersing by giving. That is, it can be obtained by the breaking down method (a method of subdividing the bulk material). Examples of the mechanical means include mechanical methods such as an ultrasonic homogenizer, a pressure homogenizer, a nanomizer, a high-speed rotary mill, a roller mill, a container driving medium mill, a medium stirring mill, a jet mill, and a sand grinder. The resulting fine silica may be colloidal or slurry.
[0028]
The method based on the condensation of active silicic acid disclosed in JP-A-2001-354408 can directly produce fine silica having the above particle diameter and pore volume without using mechanical means, and has a particle size distribution. Since it is narrow, the transparency and gloss of the ink receiving layer are good, so that it can be preferably used in the present invention. Here, the activated silicic acid refers to an aqueous silicic acid solution having a pH of 4 or less obtained by ion-exchange treatment of an aqueous alkali metal silicate solution with a hydrogen cation exchange resin, for example. SiO₂The concentration is preferably 1 to 6% by mass, more preferably 2 to 5% by mass and an active silicic acid aqueous solution having a pH of 2 to 4. The alkali metal silicate may be a commercially available industrial product, more preferably SiO.₂/ M₂It is preferable to use sodium water glass having a molar ratio of O (where M represents an alkali metal atom) of about 2 to 4.
[0029]
As a method for condensing active silicic acid, the above active silicic acid aqueous solution is dropped into hot water, or the active silicic acid aqueous solution is heated to produce seed particles, before the dispersion is precipitated or gelled. The alkali is added to stabilize the seed particles, and then the active silicic acid aqueous solution is added to the SiO particles contained in the seed particles while maintaining the stable state.₂SiO per mole₂Silica fine particles obtained by growing primary particles of seed particles by adding at a rate of preferably 0.001 to 0.2 mol / min in terms of
[0030]
The electrolyte used may be any of an inorganic acid, an inorganic base, a salt, an organic acid, and an organic base, but a strong electrolyte is preferable because the amount added can be reduced. Moreover, the thing whose solubility in 100g of water is 0.01g or more at 25 degreeC is preferable.
Examples of preferred electrolytes include sodium sulfate, sodium chloride, sodium hydrogen sulfate, sodium nitrate, sodium acetate, sodium formate, sodium carbonate, sodium bicarbonate, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, Sodium thiosulfate, potassium sulfate, potassium chloride, potassium hydrogen sulfate, potassium nitrate, potassium acetate, potassium formate, potassium carbonate, potassium hydrogen carbonate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium thiosulfate, etc. Alkali metal salt, calcium sulfate, calcium chloride, calcium nitrate, calcium acetate, calcium formate, calcium carbonate, calcium hydrogen phosphate, calcium dihydrogen phosphate, tricalcium phosphate, barium sulfate, barium chloride, nitric acid Alkaline earth metal salts such as lithium, barium acetate, barium formate, barium carbonate, barium hydrogen phosphate, barium dihydrogen phosphate, tribarium phosphate, magnesium sulfate, magnesium chloride, magnesium nitrate, magnesium acetate, magnesium carbonate, chloride Manganese, manganese acetate, manganese formate, cupric chloride, copper sulfate, cobalt chloride, nickel sulfate, nickel chloride, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate, aluminum chloride, ferrous bromide , Ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate, zinc sulfate, and other water-soluble salts, lithium hydroxide, sodium hydroxide, hydroxide Potassium, calcium hydroxide, strontium hydroxide, barium hydroxide Although the like without limitation. These electrolytes can be used not only alone but also in combination of two or more.
[0031]
In particular, alkali metal salts and alkaline earth metal salts can be easily mixed with water-based paints and easily cause pigment aggregation in the drying process after application of the water-based paint. Therefore, it is preferably used. Further, strong acid salts of alkali metals and alkaline earth metals, that is, hydrochlorides, sulfates, etc. can be most stably used in water-based paints, and are most preferably used because they do not settle even in alkalinity. Sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, SulfurExamples thereof include calcium acid. In particular, alkali metal hydrochlorides and sulfates are preferred.
[0032]
In Japanese Patent Application Laid-Open No. 61-47290, a weak acid salt of an alkali metal is used, but it is limited to the weak acid salt, and the secondary particle diameter of the pigment used is 0.5 to 30 μm. The big point is different from the present invention. In the present invention, an electrolyte such as a water-soluble salt is used for the purpose of causing particle aggregation and preventing cracking in the drying step, and is not particularly limited to weak alkali metal salts.
[0033]
In Japanese Patent Application Laid-Open No. 2001-96897, gas phase method silica and a water-soluble metal compound are used. However, the pigment used is gas phase method silica, and the film surface pH is an acidic region of 3-5. The point is different from the present invention. The present invention is different from Japanese Patent Application Laid-Open No. 2001-96897 in which a polyvalent metal salt is used in that a fine silica by a wet method and an electrolyte are used in combination, and an alkali metal salt is preferably used as the electrolyte. Further, the film surface pH of the porous ink receiving layer in the present invention is preferably 5 or more, which is different from JP-A-2001-96897. The film surface pH of the porous ink receiving layer of the present invention is not particularly limited, but is preferably 5 or more, and the upper limit is not particularly limited but is about 10. It is preferable to maintain the film surface pH at 5 or more with less cracking.
[0034]
The binder resin used is polyvinyl alcohol. Even if a binder resin other than polyvinyl alcohol is used, the ink receiving layer is cracked and the ink absorbability is not good, so that it cannot be used. The reason why polyvinyl alcohol is good is not clear, but it is considered that it has a moderate interaction with silica and agglomerates silica by a synergistic effect with a water-soluble salt.
[0035]
The saponification degree of polyvinyl alcohol is particularly preferably 90% or more, and most preferably 95% or more. A higher degree of saponification results in fewer ink receiving layer cracks and better ink absorbency. The reason is considered that polyvinyl alcohol (PVA) having a high saponification degree and containing many hydroxyl groups interacts more strongly with silica and promotes aggregation. The degree of polymerization is preferably 1700 or more, more preferably 2500 or more, and most preferably 3500 or more. There is no particular upper limit, but it is about 10,000. The higher the degree of polymerization, the fewer the ink receiving layer cracks.
[0036]
The present inventionIsWater-based paintPH ofIs adjusted to 7 or more, preferably 8 or more. Set pH to 7 or higherthingByIn order to promote the formation of a large aggregate structure in the drying process, it is preferably used for obtaining the ink jet receiving layer of the present invention. There is no particular upper limit to the pH, but it is about 10, for example. The method for adjusting the pH is not particularly limited, but a method of adding ammonia, sodium hydroxide, or potassium hydroxide to the aqueous paint is simple and effective, and is preferably used.
[0037]
In addition to fine silica, polyvinyl alcohol, and electrolyte, various additives are used depending on the purpose. For example, a cationic resin as an ink fixing agent can be used. Examples of the cationic resin include N, N-dimethylaminoethyl acrylate quaternized product, N, N-dimethylaminoethyl methacrylate quaternized product, N, N-dimethylaminopropyl acrylamide quaternized product, vinyl imidazolium methochloride, Examples of the resin include structural units having cationic properties such as diallyldimethylammonium chloride, methyldiallylamine salt, diallylamine salt, monoallylamine salt, and amidine ring. When these cationic resins are added to a dispersion of an anionic pigment such as silica and added, the paint temporarily gels due to the electrostatic properties of both, but is redispersed using mechanical means such as a homogenizer. Can be used. Moreover, it is also possible to mix | blend an alumina sol etc. as a cationic substance. However, since the addition of the cationic resin tends to worsen the cracking of the ink receiving layer, the addition is applied to the ink receiving layer by, for example, applying or impregnating an aqueous solution of the cationic resin after forming the ink receiving layer. It is preferable to include.
[0038]
Other additives such as dispersants, thickeners, antifoaming agents, colorants, antistatic agents, wetting agents used in the production of general coated papers, and for improving the storage stability of printed images UV absorbers and light stabilizers can be added as appropriate.
[0039]
The support in the present invention is not particularly limited, but is a paper or film, for example, a synthetic resin film such as polyethylene terephthalate, polyvinyl chloride, polycarbonate, polyimide, cellulose triacetate, cellulose diacetate, polyethylene, polypropylene, or polyethylene laminated paper. It is preferable to use a non-permeable support such as a synthetic resin laminated paper such as a high gloss inkjet recording sheet. The 75 degree specular gloss of the non-permeable support is preferably 60% or more, more preferably 80% or more, and most preferably 100% or more. The 75 degree specular gloss in the present invention is measured according to JIS standard P8142.
[0040]
These supports can be coated with an undercoat layer or subjected to various easy adhesion treatments such as corona discharge treatment when the adhesive strength with the ink receiving layer formed on the surface is insufficient. The thickness of the support is preferably 50 to 500 μm in consideration of the paper passing property of the printer.
[0041]
As a coating method of the aqueous paint in the present invention, a known coating means, for example, a bar coating method, a roll coating method, a blade coating method, an air knife coating method, a gravure coating method, a die coating method, a curtain coating method, or the like is used. However, it is not limited to these.
[0042]
The coating amount of the ink receiving layer is 1 to 50 g / m as the mass after drying.²The degree is preferable, more preferably 3 to 25 g / m.²It is. 1 g / m here²If it is less, there is a risk that ink absorption will be insufficient, and 50 g / m²If it is increased, curling may occur easily and the cost will be increased.
[0043]
Next, pore distribution measurement using a mercury porosimeter will be described. The pore distribution was obtained by calculating the pore distribution from a void amount distribution curve obtained by a mercury intrusion method using a micrometric pore sizer 9320 (manufactured by Shimadzu Corporation). The measurement of the pore diameter by the mercury intrusion method was calculated using the following formula derived assuming that the cross section of the pore was circular.
[0044]
D = -4γCOSθ / P
However, D: pore diameter, γ: mercury surface tension, θ: contact angle, P: pressure.
The surface tension of mercury was 482.536 dyn / cm, the contact angle used was 130 °, and high-pressure part measurement (0 to 30000 psia, measurement pore diameter of 6 μm to 6 nm) was performed. The average pore volume of the ink receiving layer is calculated from the mass of the ink receiving layer measured in advance and the void amount distribution curve. The pore distribution curve of the ink receiving layer in the present invention has a peak in the range of 6 nm to 150 nm, and the base of the peak often extends to 1 μm. Therefore, the pore volume in the range of 6 nm to 1 μm is integrated. Asked.
[0045]
Next, the porous ink receiving layer essential to the present invention will be described. The porous ink receiving layer in the present invention has a wet ink fine silica having an average particle size of 0.5 μm or less, a porous ink receiving layer containing an electrolyte and polyvinyl alcohol, and is formed by the method described above. . In order to realize an ink jet recording sheet that is excellent in ink absorption speed and ink absorption, which is a feature of the present invention, and does not cause film formation defects due to cracks during drying in the manufacturing process, the porous ink receiving layer is thin. The pore distribution preferably has the following characteristics. That is, the pore distribution curve obtained by the measurement using the mercury porosimeter has two peaks in the range of the pore diameter of 6 nm to 150 nm as shown in FIG. . Preferably, one of the two peaks is in the range of 8 nm to 25 nm, or one broad peak having a shoulder extends to the range of 8 nm to 25 nm. The pores in this range have the advantage of being able to absorb the ejected ink instantly because the capillary force is strong, but there is also the disadvantage that film formation failure due to cracking is likely to occur in the drying process of the ink receiving layer. However, if there is another pore peak in the pore diameter range of 6 nm to 150 nm, or if there is a single peak but a broad feature, the capillary contraction force due to the presence of a large number of large pores. And the cracking of the ink receiving layer in the drying process can be prevented. In addition, the presence of many large-diameter pores increases the pore volume that contributes to ink absorption, so that a large amount of ink once absorbed by the pores in the range of 8 nm to 25 nm can be taken in immediately. The ink can be absorbed without overflowing even if the ink is ejected.
[0046]
An example having two peaks in this range is also described in the example of Japanese Patent Laid-Open No. 9-183267. This is because one ink in each receiving layer is provided when two ink receiving layers are provided. Each existing peak appears. On the other hand, in the porous ink receiving layer in the present invention, at least one receiving layer has two peaks in the pore diameter range of 6 nm to 150 nm, or one broad peak having a shoulder. The point that two peaks exist is different from that of JP-A-9-183267.
[0047]
When the pore diameter peak exists only in the range of less than 6 nm, a sufficient ink absorption speed cannot be obtained, and there is a possibility that unevenness in print density called ink overflow or beading may occur. In addition, in the receiving layer that exists only in the range where the peak of the pore diameter exceeds 150 nm, the ink is likely to spread, and a clear image may not be obtained. In addition, transparency may be reduced, print density may be reduced, and glossiness may be lost.
[0048]
In the pore distribution curve of the porous ink receiving layer measured by the above method, the absolute value of the difference between the mode pore diameter and the median pore diameter is preferably 10 nm or more, more preferably more than 20 nm. . The larger the difference between the mode pore diameter and the median pore diameter, the wider the peak, and the shoulder is clearly recognized. Eventually, the shoulder is separated as a clear peak, resulting in two peaks. If it is smaller than 10 nm, the peak in the pore distribution curve becomes one sharp peak, and there is a possibility that cracking may occur when the ink receiving layer is applied and dried because there is no variation in pore size and the capillary contraction force is difficult to relax. is there. There is no upper limit to the difference value, but it is preferably less than about 100 nm.
[0049]
The porous ink receiving layer measured by the above method has a pore volume of 0.5 to 2.0 ml / g, preferably 0.5 to 1.8 ml / g, in the pore diameter range of 6 nm to 1 μm. More preferably, it is 0.6-1.5 ml / g. When the pore volume having a pore diameter of 6 nm to 1 μm is larger than 0.5 ml / g, the ink receiving layer can sufficiently absorb a large amount of ejected ink, and the image is not disturbed due to ink overflow. On the other hand, when the pore volume having a pore diameter of 6 nm to 1 μm is 2.0 ml / g or less, the dye fixing property is excellent and the strength of the ink receiving layer is also excellent.
[0050]
In the present invention, an ink jet recording sheet having a high gloss of photographic printing paper is obtained by providing a glossy expression layer on the porous ink receiving layer. The method of providing the glossy expression layer is not particularly limited, but the following two modes are preferably used in order to have a gloss of photographic printing paper and to have a high ink absorption rate and an ink absorption amount. .
[0051]
In the first aspect, on the porous ink receiving layer in the present invention, a coating liquid containing a fine pigment is applied and then dried to provide at least one glossy expression layer. Various pigments can be used as the fine pigment. Silica, aluminum hydroxide, boehmite, pseudoboehmite, and alumina having an average particle size of 1 μm or less have a large pore volume and are excellent in ink absorbability. Furthermore, it is preferable that the fine pigment is a secondary particle composed of primary particles having an average primary particle diameter of 5 to 100 nm, preferably 6 to 40 nm, because the pore volume is high. The average particle size of the secondary particles in which the primary particles are aggregated is 1 μm or less, preferably 9 to 800 nm, more preferably 10 to 600 nm, and most preferably 15 to 400 nm.
Further, when colloidal silica is used, the gloss is particularly excellent.
[0052]
As the binder resin contained in the coating liquid, a water-dispersible resin or a water-soluble polymer can be used, but a water-soluble polymer is preferable. Examples include polyvinyl alcohol, polyethylene oxide, polyalkylene oxide, polyvinyl pyrrolidone, water-soluble polyvinyl acetal, poly-N-vinylacetamide, polyacrylamide, polyacryloylmorpholine, polyhydroxyalkyl acrylate, polyacrylic acid, hydroxyethylcellulose, methylcellulose, Examples thereof include water-soluble resins such as hydroxypropylmethylcellulose, hydroxypropylcellulose, gelatin, and casein, and water-soluble derivatives thereof. Furthermore, water-dispersible resins such as SBR latex and NBR latex can be used, but water-soluble resins are preferred. Moreover, these resins can be used not only alone but also in combination of two or more.
[0053]
The coating amount of the glossy layer is 0.5 to 10 g / m as the mass after drying.²The degree is preferable, more preferably 2 to 8 g / m.²It is. Where 0.5 g / m²If it is less, there is a possibility that the expression of gloss is insufficient, 10 g / m²If it is larger, cracks may occur during drying.
[0054]
When silica is used as the fine pigment in the glossy layer, cation-modified silica is also preferably used to improve ink fixability. For example, JP-A-2001-80204 contains fumed silica and a cationic compound. An ink jet recording sheet having both high gloss and high printing density is obtained by applying a coating liquid containing a slurry mixture in which the dispersion is dispersed or pulverized to a mean particle size of 1 μm or less by mechanical pulverization.
[0055]
The second aspect is a method of providing a gloss developing layer (hereinafter referred to as a cast coating layer) by a casting method. Cast method is a smooth cast drum (drum made of mirror-finished metal, plastic, glass, etc.), mirror-finished metal plate, plastic sheet or film (film transfer cast method, film cast method) It is a method of obtaining a smooth and glossy coating layer surface by drying on a glass plate and copying the smooth surface onto the coating layer. As a method of providing a cast coating layer using a mirror surface drum, a coating liquid for a cast coating layer is applied onto the porous ink receiving layer in the present invention, and the coating layer is in a wet state. Examples include a method in which the heated mirror drum is pressed and dried to finish (wet casting method), or a method in which the heated mirror drum is pressed and dried after being wetted again and dried (rewet cast method). . Further, it is also possible to employ a method (precast method) in which a coating liquid for cast coating layer is directly applied to a heated mirror drum, and then pressed and dried on the porous ink receiving layer surface of the present invention.
[0056]
The surface temperature of the mirror drum is preferably about 40 to 200 ° C, more preferably 70 to 150 ° C. If it is less than 40 ° C., drying takes time, the gloss may be lowered, and the productivity may be lowered. When the temperature is higher than 200 ° C., the paper surface may be rough or the gloss may be lowered.
[0057]
When the coating liquid for the cast coating layer is applied onto the porous ink receiving layer of the present invention, and finished by pressing and drying on a heated mirror drum while the ink receiving layer is in a wet state, the cast coating layer is used. For the purpose of suppressing the penetration of the coating liquid for the working layer, a method for promoting the immobilization of the coating liquid for the cast coating layer can also be adopted. As this method, for example, (1) a gelling agent that promotes immobilization of the coating liquid for cast coating layer is blended in the porous ink receiving layer, and (2) cast on the porous ink receiving layer. Apply and impregnate a gelling agent that promotes immobilization of the coating layer coating solution. (3) After applying the cast coating layer coating solution, the cast coating layer coating solution is immobilized. (4) A gelling agent that promotes immobilization in the course of drying of the coating liquid is blended in the coating liquid for the cast coating layer. It is mentioned. Examples of such a gelling agent include boric acid, formic acid and the like, and salts thereof, aldehyde compounds, epoxy compounds, and the like, which are crosslinking agents for adhesives in the coating liquid for cast coating layers. Among the above methods, when the wet casting method is adopted, it is better to apply the cast coating solution on the porous ink receiving layer, press the pressure on the mirror drum and dry it as much as possible. Since the penetration of the liquid is suppressed, gloss is easily developed. Further, immediately before the surface of the porous ink receiving layer is pressed against the drum, a cast coating liquid is applied between the porous ink receiving layer surface on the pressure contact roll (press roll) and the mirror drum and immediately pressed (nip cast method). However, the penetration of the coating liquid is suppressed as much as possible, and good gloss and print quality can be easily obtained with a small coating amount, which is particularly preferable.
[0058]
The coating liquid for the cast coating layer is not particularly limited, but preferably 40 obtained by polymerizing a monomer having an ethylenically unsaturated bond as disclosed in, for example, JP-A-07-089220. Examples thereof include a coating liquid containing a polymer having a glass transition point of ° C or higher. Examples of a polymer obtained by polymerizing a monomer having an ethylenically unsaturated bond (hereinafter referred to as an ethylenic monomer) include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, and glycidyl acrylate. Methacrylic acid having 1 to 18 alkyl groups such as acrylic acid ester having 1 to 18 alkyl groups such as methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, etc. Ester, styrene, α-methylstyrene, vinyl toluene, acrylonitrile, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl propionate, acrylamide, N Methylol acrylamide, ethylene, a polymer obtained by polymerizing ethylene monomers such as butadiene. Moreover, the copolymer which used together 2 or more types of ethylenic monomers may be sufficient as needed, and another monomer can also be copolymerized. Among these, styrene-acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers are particularly preferable.
[0059]
Furthermore, the polymer may be a substituted derivative of these polymers or copolymers. Incidentally, examples of the substituted derivative include, for example, a carboxylated one, or an alkali-reactive one. Further, the above ethylenic monomer may be polymerized in the presence of colloidal silica and used in the form of a composite by Si—O—R (R: polymer component) bond. The polymer obtained by polymerizing the above ethylenic monomer preferably has a glass transition point of 40 ° C. or higher, more preferably from about 50 ° C. to about 100 ° C. Most preferably, it is about 70 ° C to about 90 ° C. The glass transition point can be adjusted by, for example, the type of ethylenic monomer and the degree of crosslinking of the polymer. For example, the glass transition point can be increased by containing 50% by mass or more of a monomer such as styrene that relatively increases the glass transition point. In the cast coating layer coating solution, a pigment such as colloidal silica can be blended in addition to the polymer, and the amount is usually about 1 part by weight to about 200 parts by weight with respect to 100 parts by weight of the polymer. Is preferred. A urethane resin can also be used.
[0060]
In the coating liquid for cast coating layers, pigments, antifoaming agents, colorants, fluorescent materials used in general printing coated paper and inkjet paper are used to adjust the whiteness, viscosity, fluidity, etc. Various auxiliary agents such as brighteners, antistatic agents, preservatives and dispersants, and thickeners are appropriately added. In addition, a release agent is preferably added to the cast coating layer coating solution for the purpose of imparting release properties from a cast drum or the like.
Examples of mold release agents include higher fatty acid amides such as stearic acid amide and oleic acid amide, polyolefin waxes such as polyethylene wax, oxidized polyethylene wax, and polypropylene wax, calcium stearate, zinc stearate, potassium oleate, and ammonium oleate. Examples thereof include higher fatty acid alkali salts, silicone compounds such as lecithin, silicone oil and silicone wax, and fluorine compounds such as polytetrafluoroethylene. The compounding quantity of a mold release agent is 0.1-50 mass parts with respect to 100 mass parts of pigments, Preferably it is 0.3-30 mass parts, More preferably, it adjusts in the range of 0.5-20 mass parts. If the blending amount is small, the effect of improving the releasability may not be obtained sufficiently. On the other hand, if the blending amount is large, the gloss may decrease, or the ink repellency or the recording density may decrease.
[0061]
It is also possible to combine the first aspect and the second aspect. That is, on the porous ink receiving layer in the present invention, according to the first aspect, a coating liquid containing a fine pigment is applied and dried to provide at least one glossy expression layer. Further, according to the second aspect, A gloss developing layer can be provided by a casting method. In this method, the gloss is particularly good.
[0062]
The 75-degree specular gloss of the ink jet recording sheet of the present invention provided with the glossy expression layer by the above method is preferably 40% or more, more preferably 50% or more, and most preferably 70% or more.
[0063]
In addition, a back layer can be provided on the side opposite to the ink receiving layer on the support in order to suppress curling of the ink jet recording sheet and improve transportability. The configuration of the back surface layer and the back surface of the support accompanying it can be selected according to its use, and are not particularly limited, but in view of coating properties and cost, the back surface layer mainly composed of a hydrophilic resin is used. It is preferable to provide it. Moreover, you may provide an adhesive layer and a peeling sheet in a back surface.
[0064]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples. In this example, unless otherwise specified, “%” indicating concentration means mass%, and “part” means mass part.
[0065]
[Method of measuring pore volume and pore diameter of silica]
An aqueous dispersion of silica was dried at 105 ° C., and the pore volume and pore size distribution of the obtained powder sample were measured using a gas adsorption method specific surface area / pore distribution measuring device (SA3100plus type manufactured by Coulter). The measurement was carried out after vacuum degassing at 200 ° C. for 2 hours. Nitrogen was used as the adsorption gas. As the pore volume, the value of the total pore volume of pores having a pore diameter of 100 nm or less was used. The pore diameter was defined as the pore diameter of the maximum volume fraction in the pore distribution curve obtained from the analysis of the desorption isotherm by the BJH method.
[0066]
[Measuring method of average secondary particle size of silica]
Using a laser particle size meter (LPA3000 / 3100, manufactured by Otsuka Electronics Co., Ltd.) by a dynamic light scattering method, measurement was performed in a state where an aqueous dispersion of silica was sufficiently diluted with distilled water. The average particle size used was a value calculated from analysis using the cumulant method.
[0067]
[Production Method of Fine Silica Dispersion A]
Synthetic amorphous silica produced by the gel method and having an average particle size of 13.1 μm (produced by Grace Devison, trade name: Silojet P612, specific surface area 290 m)²/ G, primary particle size 9 nm) in a water dispersion at a concentration of 20%, a slurry prepared by adding aqueous ammonia and adjusting the pH to 9.0 was obtained by using a horizontal bead mill (Shinmaru Enterprises Co., Ltd., Dino Mill KDL-Pilot). ) Were repeatedly pulverized and dispersed to produce a 20% aqueous dispersion of silica having an average secondary particle size of 300 nm. The specific surface area of this silica fine pigment is 290 m.²/ G, and the pore volume was 0.7 ml / g.
[0068]
[Method for producing fine silica dispersion B]
(Preparation of active silicic acid aqueous solution)
SiO₂Concentration 30%, SiO₂/ Na₂Distilled water was mixed with a sodium silicate solution (No. 3 sodium silicate, manufactured by Tokuyama Corporation) having an O molar ratio of 3.1, and SiO 2₂A dilute sodium silicate aqueous solution having a concentration of 4.0% was prepared. This aqueous solution was passed through a column filled with a hydrogen-type cation exchange resin [Diaion SK-1BH, manufactured by Mitsubishi Chemical Corporation] to prepare an active silicic acid aqueous solution. SiO in the obtained active silicic acid aqueous solution₂The concentration was 4.0% and the pH was 2.9.
(Preparation of seed solution)
In a 5 liter glass reaction vessel equipped with a reflux, a stirrer, and a thermometer, 400 g of distilled water was heated to 100 ° C. While maintaining this hot water at 100 ° C., a total of 480 g of the above active silicic acid aqueous solution was added at a rate of 8 g / min to prepare a seed solution.
(Preparation of fine silica dispersion)
To the seed solution, 13.5 g of a potassium hydroxide solution having a concentration of 1 mol / liter was added at a time to stabilize. While maintaining the seed solution at 100 ° C., an additional 920 g of the above active silicic acid aqueous solution was added at a rate of 8 g / min. After completion of the addition, the mixture was heated to reflux for 1 hour while maintaining at 100 ° C. to obtain a fine silica dispersion. The dispersion was a pale milky white transparent solution having a pH of 8.6. The properties of this fine silica dispersion are as follows: average secondary particle size 99 nm, primary particle size 14 nm, specific surface area 193 m²/ G, pore volume 0.62 ml / g, and pore diameter 13.5 nm. This dispersion is concentrated to 20% silica concentration with an evaporator, hydrogen cation exchange resin [Diaion SK-1BH, manufactured by Mitsubishi Chemical Corporation] is added and stirred to remove potassium hydroxide, and then ammonia is added. The pH was adjusted to 9.0 with water and used for production of an ink jet recording sheet.
[0069]
[Method for producing fine silica dispersion C]
Silica (produced by Nippon Aerosil Co., Ltd., trade name: AEROSIL130) produced by the gas phase method is dispersed in water at a concentration of 20%, and the pH is adjusted to 2.5 with hydrochloric acid, followed by a hydraulic method. A 20% aqueous dispersion of silica having an average secondary particle size of 250 nm was prepared by dispersing the mixture three times with an ultra-high pressure homogenizer (manufactured by Mizuho Kogyo Co., Ltd., Microfluidizer M110-E / H). The specific surface area of this silica fine pigment is 137m.²/ G, the pore volume was 1.2 ml / g.
[0070]
[Method for producing cation-modified fine silica dispersion D]
A 11% aqueous dispersion of silica (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL300) having an average primary particle size of 9 nm produced by a gas phase method was used in a hydraulic ultra-high pressure homogenizer used in the method for producing silica sol C. Dispersed 3 times. The specific surface area of this fine silica is 308m.²/ G, the pore volume was 1.6 ml / g. 10 parts of an 11% aqueous solution of diallyldimethylammonium chloride / acrylamide copolymer (manufactured by Nitto Boseki Co., Ltd., trade name: PAS-J-81), which is a cationic resin as an ink fixing agent, is added to 100 parts of the dispersion. Then, the gelled mixture was further dispersed with the same homogenizer to produce an aqueous silica dispersion having an average secondary particle size of 100 nm. This dispersion had a solid content of 11%, a silica concentration of 10%, and a diallyldimethylammonium chloride / acrylamide copolymer concentration of 1%.
[0072]
[Fine silica dispersionEManufacturing method]
Silica having the same specific surface area and a large pore volume was produced in the same manner as the fine silica dispersion B. The activated silicic acid used and the production equipment are the same.
In a glass reaction vessel, 400 g of distilled water was heated to 100 ° C. While maintaining this hot water at 100 ° C., a total of 1120 g of the above-mentioned active silicic acid aqueous solution was added at a rate of 16 g / min to prepare a seed solution.
27 g of potassium hydroxide solution with a concentration of 1 mol / liter is added to the seed solution at a time.CheapQualified. While maintaining the seed solution at 100 ° C., an additional 1760 g of the above active silicic acid aqueous solution was added at a rate of 16 g / min. After completion of the addition, the mixture was heated to reflux for 1 hour while maintaining at 100 ° C. to obtain a fine silica dispersion. The dispersion was a pale milky white transparent solution having a pH of 8.8. The properties of this fine silica dispersion are as follows: average secondary particle size 154 nm, primary particle size 14 nm, specific surface area 198 m²/ G and pore volume 1.10 ml / g. This dispersion was concentrated to an silica concentration of 20% with an evaporator, and hydrogen type cation exchange resin [manufactured by Mitsubishi Chemical Co., Ltd., Diaion SK-1BH] was added and stirred to remove potassium hydroxide. The pH was adjusted to 9.0 with water and used for production of an ink jet recording sheet.
[0073]
[Fine silica dispersionFManufacturing method]
Silica having the same specific surface area and small pore volume was produced in the same manner as the fine silica dispersion B. The active silicic acid and the production equipment used are the same.
In a glass reaction vessel, 400 g of distilled water was heated to 100 ° C. While keeping the hot water at 100 ° C., a total of 360 g of active silicic acid was added at a rate of 16 g / min to prepare a seed solution.
To this seed solution, 9 g of potassium hydroxide solution having a concentration of 1 mol / liter was added at a time to stabilize. While maintaining the seed solution at 100 ° C., a total of 560 g of active silicic acid was added at a rate of 16 g / min. After completion of the addition, the mixture was heated to reflux for 1 hour while maintaining at 100 ° C. to prepare a fine silica dispersion. The dispersion was a light bluish clear solution having a pH of 8.8. The properties of the fine silica dispersion are as follows: average secondary particle diameter 51 nm, primary particle diameter 14 nm, specific surface area 190 m²/ G and pore volume 0.35 ml / g. This dispersion was concentrated to an silica concentration of 20% with an evaporator, and hydrogen type cation exchange resin [manufactured by Mitsubishi Chemical Co., Ltd., Diaion SK-1BH] was added and stirred to remove potassium hydroxide. The pH was adjusted to 9.0 with water and used for production of an ink jet recording sheet.
[0074]
[Manufacture of base paper]
Conifer bleached kraft pulp (NBKP) beaten to 250 ml by CSF (JIS P-8121) and hardwood bleached kraft pulp (LBKP) beaten to 280 ml by CSF were mixed at a mass ratio of 2: 8, and the concentration was 0. A 5% pulp slurry was prepared. In this pulp slurry, cationized starch 2.0%, alkyl ketene dimer 0.4%, anionized polyacrylamide resin 0.1%, polyamide polyamine epichlorohydrin resin 0.7% is added to the pulp dry mass, and sufficient And dispersed with stirring. The pulp slurry of the above composition is made with a long net machine, passed through a dryer, a size press, and a machine calendar, and a basis weight of 180 g / m.², Tension 1.0g / cm³Base paper was manufactured. The size press solution used in the size press step was prepared by mixing carboxyl-modified polyvinyl alcohol and sodium chloride at a mass ratio of 2: 1, adding this to water and dissolving it by heating, and adjusting the concentration to 5%. A total of 25 cc was applied to both sides of the paper to obtain a base paper.
[0075]
[Manufacture of support]
After applying corona discharge treatment to both sides of the support base paper, the following polyolefin resin composition 1 mixed and dispersed by a Banbury mixer is applied to the felt side of the base paper at a coating amount of 25 g / m.²In addition, the coating amount of the polyolefin resin composition 2 (back surface resin composition) on the wire surface side is 20 g / m.²Then, it was coated with a melt extruder having a T-shaped die (melting temperature: 320 ° C.), and the felt side was cooled and solidified with a cooling roll with a mirror surface and the wire side with a rough surface. A resin-coated support having a J.TAPPI No. 5) of 6000 seconds and an opacity (JIS P8138) of 93% was produced.
(Polyolefin resin composition 1) Long chain type low density polyethylene resin (density 0.926 g / cm³, 35 parts melt index 20 g / 10 min, low density polyethylene resin (density 0.919 g / cm)³, Melt index 2 g / 10 min) 50 parts, anatase titanium dioxide (A-220; manufactured by Ishihara Sangyo) 15 parts, zinc stearate 0.1 part, antioxidant (Irganox 1010; manufactured by Ciba Geigy) 0.03 parts, ultramarine (Aoguchi Ultramarine No. 2000; manufactured by Daiichi Kasei) 0.09 parts, fluorescent whitening agent (UVITEX OB; manufactured by Ciba Geigy) 0.3 parts (polyolefin resin composition 2) high density polyethylene resin (density 0.954 g / cm³, 65 parts of melt index 20 g / 10 min), low density polyethylene resin (density 0.924 g / cm)³, Melt index 4g / 10min) 35 parts
[0076]
<Example 1>
Polyvinyl alcohol (product name: PVA-140, manufactured by Kuraray Co., Ltd.) having 0.5 parts of a 10% aqueous solution of sodium chloride, 100% saponification degree, and 98.5% saponification degree, and 4000 degree of polymerization. 40 parts of a 10% aqueous solution) is prepared, and a paint having a solid content concentration of 17.1% containing 0.25 parts of sodium chloride and 20 parts of polyvinyl alcohol is added to 100 parts of silica, and ion-exchanged water is added. The concentration was 16.0%. The main components and pH of the paint are shown in Table 1. The coating amount of this paint on a support is 20 g / m in dry mass.²Bar coating was applied so that This coating was dried at 120 ° C. to provide a porous ink receiving layer.
Subsequently, a coating solution obtained by mixing 22 parts of a 10% aqueous solution of polyvinyl alcohol having a saponification degree of 98.5% with 100 parts of cation-modified fine silica dispersion D (concentration 11%) on the ink receiving layer. The coating weight is 5 g / m in dry mass²Bar coating was applied so that This coating film was dried at 120 ° C. to provide a glossy layer, and an ink jet recording sheet was produced. The method of laminating the glossy layer of the ink jet recording sheet is shown in Table 1, and the pore distribution, cracks, film surface pH, and quality of the ink jet recording sheet of the porous ink receiving layer were evaluated by the following methods. .
[0077]
[Measurement of pore distribution in porous ink receiving layer]
The pore distribution of the porous ink receiving layer in the inkjet recording sheets of Examples and Comparative Examples of the present invention was measured as follows using the ink receiving layer before providing the glossy layer. The ink-receptive layer coating material was applied to a PET film and the sample peeled off with a knife was measured. Using a micrometric pore sizer 9320 (manufactured by Shimadzu Corporation), the pore distribution was calculated from the void amount distribution curve obtained by the mercury intrusion method, and the peak position and the mode pore diameter were obtained. Moreover, it calculated | required by integrating | accumulating the pore volume in the range of 6 nm-1 micrometer from the obtained pore distribution curve. In the receiving layer of each example and comparative example, the number of peaks in the pore diameter range of 6 to 150 nm, the peak position, the mode pore diameter, the median pore diameter, the absolute value of the difference between the mode pore diameter and the median pore diameter, and the pore diameter of 6 nm. The pore volume in the range of ˜1 μm is shown in Table 2.
[0078]
[Crack of porous ink receiving layer]
The evaluation of the crack of the porous ink receiving layer in the present invention was performed visually on the ink receiving layer before providing the glossy layer, and the cracking situation in the 10 cm × 10 cm sheet was evaluated in the following three stages.
◎: No crack
○: There are several cracks over 1mm, but good
×: There are cracks on the entire surface, and there are practical problems.
[0079]
[Film surface of porous ink receiving layer pH]
The film surface pH of the porous ink receiving layer in the present invention is the same as that of the ink receiving layer before the gloss developing layer is provided. TAPPI paper pulp test method no. In accordance with the method described in No. 49, the film surface pH was determined by using the value of the surface pH measured after 30 seconds using distilled water.
[0080]
Inkjet recording sheet quality evaluation method
[75 ° specular gloss]
It measured according to JIS standard P8142.
[0081]
[Ink absorption speed]
The ink absorption rate of the ink jet recording sheet in the present invention was evaluated by the following method. 100% cyan, 100% magenta, 100% yellow, and 100% black solids were printed on the ink jet recording sheet in the recommended setting print mode for exclusive use of super fine paper of an ink jet printer (manufactured by EPSON, PM-800C). The PPC paper was pressed against the printing part by hand, and it was visually checked whether or not the ink was transferred. The time until the transfer disappeared was measured and evaluated in the following three stages.
◎: Less than 1 second
○: 1 second or more and less than 30 seconds
×: 30 seconds or more
[0082]
[Ink absorption]
The ink absorption amount of the inkjet recording sheet in the present invention was evaluated by the following method. A 100% red, 100% green, and 100% blue mixed color solid was printed on the inkjet recording sheet by the above method, and the presence or absence of ink overflow and the uniformity of the printing density were evaluated in the following three stages.
A: No ink overflow and good uniformity.
○: There is no ink overflow, but the density is slightly uneven.
X: Ink overflow is observed.
[0083]
<Example 2>
To 100 parts of fine silica dispersion A, 0.5 part of a 10% aqueous solution of sodium sulfate and 40 parts of a 10% aqueous solution of polyvinyl alcohol used in Example 1 were mixed. Example 1 except that a paint having a solid content concentration of 17.1% containing 25 parts and 20 parts of polyvinyl alcohol was prepared, and a paint having a concentration of 16.0% diluted by adding ion-exchanged water was used. A porous ink receiving layer and a glossy expression layer were provided by the method described above to produce an ink jet recording sheet. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0084]
<Example 3>
To 100 parts of fine silica dispersion A, 1 part of a 10% aqueous solution of sodium sulfate, polyvinyl alcohol having a saponification degree of 95.0% and a polymerization degree of 3500 (manufactured by Kuraray Co., Ltd., trade name: PVA-635) Mix 40 parts of 10% aqueous solution, prepare a paint with a solid content concentration of 17.1% containing 0.5 parts of sodium sulfate and 20 parts of polyvinyl alcohol to 100 parts of silica, and dilute with ion-exchanged water A porous ink receiving layer and a glossy expression layer were provided in the same manner as in Example 1 except that the coating material having a concentration of 16.0% was used, and an ink jet recording sheet was produced. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0085]
<Example 4>
To 100 parts of fine silica dispersion A, 0.5 part of a 10% aqueous solution of sodium carbonate and 40 parts of a 10% aqueous solution of polyvinyl alcohol used in Example 1 were mixed. Example 1 except that a paint having a solid content concentration of 17.1% containing 25 parts and 20 parts of polyvinyl alcohol was prepared, and a paint having a concentration of 16.0% diluted by adding ion-exchanged water was used. A porous ink receiving layer and a glossy expression layer were provided by the method described above to produce an ink jet recording sheet. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0086]
<Example 5>
To 100 parts of fine silica dispersion B, 1 part of a 10% aqueous solution of sodium chloride and 40 parts of a 10% aqueous solution of polyvinyl alcohol used in Example 1 were mixed. The same method as in Example 1 except that a paint having a solid content concentration of 17.0% containing 20 parts of polyvinyl alcohol was prepared, and a paint having a concentration of 16.0% diluted by adding ion-exchanged water was used. A porous ink receiving layer and a glossy expression layer were provided to prepare an ink jet recording sheet. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0087]
<Example 6>
To 100 parts of fine silica dispersion B, 2 parts of a 10% aqueous solution of sodium sulfate and 40 parts of a 10% aqueous solution of polyvinyl alcohol used in Example 1 are mixed, and 1 part of sodium sulfate is added to 100 parts of silica. A porous material was prepared in the same manner as in Example 1 except that a coating material having a solid content concentration of 16.9% containing 20 parts of polyvinyl alcohol was prepared, and a coating material having a concentration of 16.0% diluted by adding ion-exchanged water was used. An ink jet recording sheet was produced by providing a quality ink receiving layer and a glossy layer. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer. The shoulder of the pore peak in Table 2 is gently present over 10-20 nm.
[0094]
<Comparative Example 1>
Fine silica dispersionEAn inkjet recording sheet having a glossy layer was produced in the same manner as in Example 5 except that was used. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0095]
<Comparative Example 2>
Fine silica dispersionFAn inkjet recording sheet having a glossy layer was produced in the same manner as in Example 5 except that was used. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0096]
<Example7>
In Example 5, an inkjet recording sheet having a glossy expression layer was produced in the same manner as Example 5 except that 1 part of a 10% aqueous solution of sodium hydroxide was used instead of 1 part of a 10% aqueous solution of sodium chloride. did. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0097]
<Comparative example3>
A porous ink receiving layer and a glossy layer were provided on the support in the same manner as in Example 1 except that sodium chloride was not added to obtain an ink jet recording sheet. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0098]
<Comparative example4>
40 parts of a 10% aqueous solution of polyvinyl alcohol (trade name: PVA-235, manufactured by Kuraray Co., Ltd.) having a degree of saponification of 88.0% and a degree of polymerization of 3500 are mixed with 100 parts of fine silica dispersion A, and silica 100 Except for preparing a paint having a solid content concentration of 17.1% containing 20 parts of polyvinyl alcohol with respect to parts, and using a paint having a concentration of 16.0% diluted by adding ion-exchanged water (no addition of electrolyte) A porous ink receiving layer and a glossy expression layer were provided in the same manner as in Example 1 to produce an ink jet recording sheet. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0099]
<Comparative example5>
A porous ink receiving layer and a glossy expression layer were provided in the same manner as in Example 5 except that sodium chloride was not added to produce an ink jet recording sheet. Table 1 shows the main component of the paint, pH, and the method of laminating the glossy layer, and Table 2 shows the pore distribution, cracks, film surface pH, and ink jet recording sheet quality of the porous ink receiving layer.
[0103]
<Comparative example6>
40 parts of a 10% aqueous solution of polyvinyl alcohol used in Example 1 was mixed with 100 parts of fine silica dispersion C, and a paint having a solid content concentration of 17.0% containing 20 parts of polyvinyl alcohol with respect to 100 parts of silica. A porous ink receiving layer was provided in the same manner as in Example 1 except that a paint having a concentration of 16.0% prepared and diluted by adding ion exchange water was used. Since this receptive layer had many large cracks, many parts were peeled off from the support, and it was not possible to apply a coating thereon. Therefore, a glossy expression layer could not be provided. The main components and pH of the paint are shown in Table 1, and the pore distribution, cracks, and film surface pH of the porous ink receiving layer are shown in Table 2.
[0104]
[Table 1]

[0105]
[Table 2]

[0106]
Like each example in Table 1,specificWet method A water-based paint having a fine silica, electrolyte and polyvinyl alcohol and having a pH of 7 or more is applied to a support and dried to provide a porous ink-receiving layer, and a gloss developing layer is provided thereon. It is a feature. Due to the effect of the water-soluble salts, a large aggregated structure is formed in the porous ink receiving layer, and the presence of a large number of large pores alleviates the capillary contraction force and prevents cracking in the drying process. As a result, as is clear from each example of Table 2, the porous ink receiving layer of each example has two peaks in the range of the pore diameter of 6 to 150 nm, or one broad peak having a shoulder. It was. In addition, the pore diameter of the receiving layer is larger than the pore diameter of the pigment, and a wide pore peak with many large pores exists as can be seen from the absolute value of the difference between the mode pore diameter and the median pore diameter of 10 nm or more. Had. Therefore, the ink absorption speed was sufficiently fast and the ink absorption amount was large. Further, the glossiness of the ink jet recording sheet was sufficiently high.
[0107]
on the other hand,ratioComparative example3-6When a porous ink-receiving layer is obtained by applying a water-based paint that does not contain electrolyte and drying to obtain a large agglomerated structure, the strong capillary contraction force during the drying process cannot be relaxed. The receiving layer produced many cracks. Therefore, comparative example3~5The glossiness was low even when a glossy layer was provided. As can be seen from the fact that there is only one pore peak in the above pore diameter range, the pore diameter of the receiving layer is not increased because no aggregate structure is formed, and therefore the ink absorption rate is slow, Since the volume is difficult to increase, the ink absorption amount is insufficient. Comparative example6Then, many large cracks were generated and peeled off from the support, so that the glossy expression layer could not be provided.
[0108]
As for the influence of the type of silica, when the fine silica dispersion B produced by condensing activated silicic acid is used, the pore volume of the ink receiving layer is the highest, the ink absorption is good, and the gloss is high. Was also good. This fine silica satisfy | filled Formula 1 and Formula 2 simultaneously.
(Formula 1) Specific surface area (m²/ G) <730-600 × pore volume (ml / g)
(Formula 2) Specific surface area (m²/ G)> 450-600 × pore volume (ml / g)
Comparative example 1 Used inFine silica dispersionEIs silica produced by condensing active silicic acid, but it does not satisfy Formula 1, but only Formula 2. In this case, the ink receiving layer was somewhat cracked.Used in Comparative Example 2Fine silica dispersionFIs an example that satisfies Formula 1 but does not satisfy Formula 2, the pore volume of the ink receiving layer is slightly lower, and the ink absorption amount is somewhat reduced.
[0109]
【The invention's effect】
Inkjet recording sheet of the present inventionDepending on the manufacturing methodThus, it was possible to produce the film without causing defective film formation due to cracking, which often becomes a problem when a fine pigment is used. Also,What was manufacturedIt has a high gloss of photographic printing paper tone, has both a high ink absorption speed and an ink absorption amount, and is suitable as an alternative to silver salt photography.
[0110]
[Brief description of the drawings]
FIG. 1 is a pore distribution curve of a porous ink receiving layer in the present invention. V represents the pore volume of the ink receiving layer, and D represents the pore diameter of the ink receiving layer.
FIG. 2 is a pore distribution curve of an ink receiving layer that does not contain an electrolyte in the ink receiving layer and has only one peak in the pore diameter range of 6 to 150 nm (outside of the present invention).
FIG. 3 shows the specific surface area and pore volume of silica on the vertical axis and horizontal axis of the graph, respectively, and the coating film haze values when each silica is applied to a substrate as a coating material are classified into five stages and described. The haze value was obtained by mixing 20 parts of a mixture of Kuraray Co., Ltd. polyvinyl alcohol 140H with 20 parts of silica.²What was coated was measured according to JIS standard K7105.

Claims (14)

On at least one surface of a support having an average particle diameter of Ri der less 0.5 [mu] m, the nitrogen specific surface area and pore volume due to adsorption method (Equation 1) and (Equation 2) meet, further specific surface area of 150 to 300 m ² / g, and after coating the fine silica pore volume is produced by 0.5～0.9Ml / g der Ru wet process, electrolytes, and pH containing polyvinyl alcohol is 7 or more aqueous paints A method for producing an ink jet recording sheet, comprising: providing a porous ink receiving layer by drying, and further providing a glossy layer.
(Formula 1) Specific surface area (m ² / g) <730-600 × pore volume (ml / g)
(Formula 2) Specific surface area (m ² / g)> 450-600 × pore volume (ml / g) The method for producing an ink jet recording sheet according to claim 1, wherein the 75 ° specular gloss (JIS P8142) is 40% or more. The method for producing an ink jet recording sheet according to claim 1, wherein the support is a non-permeable support. The method for producing an ink jet recording sheet according to claim 3, wherein the non-air-permeable support has a 75-degree specular gloss (JIS P8142) of 60% or more. The method for producing an ink jet recording sheet according to any one of claims 1 to 4, wherein the fine silica is secondary particles having an average particle diameter of 8 nm to 500 nm formed by agglomerating primary particles having an average particle diameter of 3 nm to 100 nm. Ink jet recording sheet manufacturing method according to any one of claims 1 to 5 the fine silica is one produced by condensing active silica. Electrolyte is sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, calcium sulfate, sodium carbonate, an ink jet recording sheet manufacturing method according to claims 1 to 6 is at least one selected from sodium hydroxide. The method for producing an ink jet recording sheet according to claim 7 , wherein the electrolyte is a strong acid salt of an alkali metal. The content of the electrolyte is, the ink jet recording sheet manufacturing method according to any one of claims 1-8 to the fine silica 100 parts by weight is the ratio of 0.05 to 5 parts by weight. Ink jet recording sheet manufacturing method according to any one of claims 1-9 saponification degree of the polyvinyl alcohol is 90% or more. Ink jet recording sheet manufacturing method according to any one of claims 1-10 polymerization degree of polyvinyl alcohol is 1700 or more. The porous ink receiving layer has two peaks in a pore diameter range of 6 nm to 150 nm or one broad peak having a shoulder in a pore distribution curve measured with a mercury porosimeter. 11. A method for producing an ink jet recording sheet according to any one of 11 above. The method for producing an ink jet recording sheet according to claim 12 , wherein the absolute value of the difference between the mode pore diameter and the median pore diameter in the pore distribution curve is 10 nm or more. The method for producing an ink jet recording sheet according to claim 12 or 13 , wherein the porous ink receiving layer has a pore volume of 0.5 to 2.0 ml / g in a pore diameter range of 6 nm to 1 µm.

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