JP4191075B2 - Inkjet recording sheet - Google Patents

Description

  The present invention relates to an ink jet recording sheet and a method for producing the same, and more particularly to an ink jet recording sheet having good ink absorbability, high recorded image density, and excellent gloss.

  The ink jet recording method is a method in which fine droplets of ink are ejected by various operating principles and adhered to a recording sheet such as paper to record images / characters. However, high speed, low noise, and multiple colors are achieved. It has features such as easy recording pattern flexibility, no need for development and fixing, and is rapidly spreading as a recording apparatus for various graphics and color images including kanji. Furthermore, images formed by the multi-color ink jet method can obtain a recording that is comparable to multi-color printing by the plate-making method and printing by the color photographic method. Since it is cheaper than the technology, it is being widely applied to the field of full-color image recording.

  As a recording sheet used in this inkjet recording method, the density of the printed dots is high, the color tone is bright and vivid, the ink does not flow out or bleed even when the printed dots overlap quickly, It is required that the lateral diffusion of the printed dots is not larger than necessary, the periphery is smooth and not blurred.

  Several proposals have been made to solve these problems. An ink jet recording paper in which a low-size base paper is wetted with a coating material for surface processing is disclosed (for example, see Patent Document 1). In addition, there is an example in which non-collagen silica powder is used as a pigment in the coating layer (see, for example, Patent Document 2 and Patent Document 3). Furthermore, an example of smear paper using a two-layer structure with different ink absorption rates is disclosed (see, for example, Patent Document 4).

  In general, an ink jet recording sheet is provided with an ink receiving layer having an ink absorption characteristic to which a porous pigment is applied, and controls color and sharpness to determine image quality, thereby improving color reproducibility and image reproducibility. ing. The ink receiving layer having ink absorptivity needs to have many voids in the ink receiving layer in order to absorb and hold ink. However, the ink-receiving layer with many voids is scattered because the incident light to the ink-receiving layer is scattered and transmission is blocked, making it opaque and making it difficult for light to reach the ink that has penetrated the voids, resulting in a whitish image. Color reproducibility and color density are reduced. Further, since the ink receiving layer having many voids has a porous surface, it is difficult to desire high gloss.

  As an inkjet recording sheet having high gloss, a method has been proposed in which a porous ink-receiving layer is formed on a transparent support, and an image formed on the ink-receiving layer is observed from the support side. (For example, refer to Patent Document 5). Also, there is a method in which a dye adsorption layer made of porous alumina hydrate and a solvent absorption layer made of porous fine powder silica are sequentially laminated on a transparent support, and an image formed on the dye adsorption layer is observed from the support side. It has been proposed (see Patent Document 6). However, in these methods, when an image is printed, it is necessary to perform image processing so that it becomes a mirror image, and further, the support used is limited to one having transparency.

  For the purpose of imparting gloss, recording paper, film, etc. coated with a resin that absorbs ink by dissolution / swelling are available. However, ink absorption and drying are slow, and the occurrence of stains and bleeding due to ink transfer becomes a problem.

JP 52-53012 A JP-A-55-51583 JP-A-56-157 Japanese Patent Laid-Open No. 55-11829 Japanese Patent Laid-Open No. 61-197285 JP-A-3-215081

  The inkjet recording method has a problem of obtaining image quality comparable to that of a so-called silver salt photograph. An object of the present invention relates to an ink jet recording sheet having good ink absorptivity, a clear recorded image, and excellent gloss, and a method for producing the same.

  As a result of intensive studies on the ink jet recording sheet, the inventors have invented the ink jet recording sheet of the present invention.

That is, the invention described in claim 1 is a recording medium in which an ink receiving layer and a glossy expression layer are provided on a support by casting, and the ink receiving layer is made of clay, silica and a hollow plastic pigment (hereinafter referred to as “a plastic layer”). Ink acceptor, wherein the ratio of clay: silica is 5: 1 to 2: 1, and the ratio of silica: hollow plastic pigment is 2: 1 to 1: 2. The absolute dry coating amount of the layer is 5 to 20 g / m ² , the absolute dry coating amount of the gloss developing layer is 5 to 70 g / m ² , and the gloss developing layer is composed of aggregates of primary particles, It is composed of fumed alumina particles having an average particle diameter of 80 to 300 nm and a binder, and the ratio of the fumed alumina particles to the binder is 100: 3 to 100: 30 by weight, and a cation is formed on the glossy layer. Be a fixing agent to impart an ink jet recording sheet according to claim.

  The invention according to claim 2 includes that the 75 degree specular gloss specified in JIS P 8142 is 40 to 95%, or the image clarity specified in JIS H 8686 is 40 to 98%. It is a waste.

  By adopting such a configuration, an image quality comparable to that of a so-called silver salt photograph can be obtained, an ink absorbability is excellent, a recorded image is clear, and an glossy ink jet recording sheet is excellent. It becomes possible to provide.

  In the present invention, the recording medium is provided with an ink receiving layer and a glossy expression layer which are coated on a support by a casting process, and the ink receiving layer contains silica and hollow PP. By using an ink receiving layer containing silica and hollow PP between the support and the gloss developing layer, the solvent component of the ink is absorbed, the ink absorbability of the gloss developing layer is improved, and the problem of ink overflow is avoided. be able to.

  The ink receiving layer in the present invention is coated by a cast treatment, so that high smoothness and glossiness can be obtained as a base before the glossy expression layer is provided, and ink absorbability can be complemented. Further, even after providing the glossy layer, it can be maintained without impairing smoothness and glossiness. The cast treatment is a processing method in which the glossy layer is pressed onto a heated mirror surface roll in a swollen state to give a mirror finish. Coating by the cast treatment in the present invention is called a cast coating method and is generally the same production method as printing cast coated paper, and includes a direct method, a gelation method, a rewet method, and the like. The direct method is a method in which a layer to be cast-processed (ink-receiving layer) is applied and then pressed against a heated mirror roll in an undried state (wet state) and dried. The gelation method is a method in which a layer to be cast-processed (ink-receiving layer) is applied, the undried layer is gelled with a gelling solution, and then pressed against a heated mirror roll and dried. is there. The rewetting method is a method in which a layer to be cast (ink receiving layer) is applied and dried, and then the layer is rewet with a wetting liquid mainly composed of water, and is pressed against a heated mirror roll and dried. It is. In the present invention, good results can be obtained by any method.

  The pigment of the ink receiving layer in the present invention can be a synthetic amorphous silica, clay, kaolin, calcined clay, light calcium carbonate, heavy calcium carbonate, magnesium carbonate as long as a sufficiently smooth and high gloss surface quality can be obtained. Inorganic pigments such as aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, aluminum hydroxide, hollow PP, styrene PP, acrylic PP, styrene-butadiene PP, styrene-acrylic PP, polyethylene PP, microcapsule, Examples thereof include organic pigments such as urea resin and melamine resin. That is, various organic and inorganic pigments known and used in the general coated paper field can be used. In addition, inorganic fine particles such as colloidal silica and alumina sol can be used in the sense of forming a surface having high smoothness and high gloss after casting.

  Examples of binders used in the ink receiving layer include starch derivatives such as oxidized starch, etherified starch, and phosphate esterified starch, casein, soy protein, synthetic proteins, starch, cellulose derivatives such as carboxymethylcellulose and methylcellulose, and polyvinyl alcohol. , Polyvinyl acetal, acrylic, polyurethane, polyvinyl pyrrolidone, styrene-acrylic copolymer, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic acid ester, methacrylic acid ester polymer or copolymer, etc. A binder that can be generally used for coated paper of vinyl latexes such as acrylic copolymer latexes, vinyl acetate, and ethylene vinyl acetate copolymers may be used in combination. Furthermore, in the ink receiving layer, as additives, dye fixing agents, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, penetrating agents, colored dyes, colored pigments, fluorescent whitening agents UV absorbers, antioxidants, antiseptics, antibacterial agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, curing agents, and the like can be appropriately blended.

  The fumed alumina used in the glossy layer of the present invention is generally alumina produced by a production method such as a dry method or a gas phase method. This is a manufacturing method in which an aluminum salt (for example, aluminum chloride or aluminum sulfate) is roasted at high temperature.

  The fumed alumina used in the present invention is an aggregate of primary particles from the viewpoint of ink absorbability and gloss, and the average particle diameter of the aggregate is preferably 80 to 300 nm, more preferably 100 to 100 nm. 200 nm. When the average particle size of the aggregate is smaller than 80 nm, the gloss is good but the ink absorbability is poor. When the average particle diameter of the aggregate is larger than 300 nm, there is a problem that gloss is inferior although ink absorbency is good. Here, the average particle diameter of the aggregate is preferably measured by a light scattering method or a laser diffraction method, more preferably photon correlation spectroscopy (PCS). The primary particle size of the fumed alumina is not particularly limited, but is preferably 1 to 50 nm.

  The weight ratio of the fumed alumina particles to the binder is preferably 100: 3 to 100: 30, and more preferably 100: 5 to 100: 20. The ratio of fumed alumina particles to binder is smaller than 100: 3, but the ink absorbency is good, but the coating layer film is not strong enough, and the surface quality deteriorates due to surface cracks. There is a problem of doing. When the ratio of the fumed alumina particles to the binder is larger than 100: 30, the coating layer film has sufficient strength and can form a good surface quality without cracking the surface, but the ink absorbability is poor. There is a problem. It is preferable that a cationic fixing agent is provided on the glossy layer.

  The cationic fixing agent is necessary for fixing the ink. However, when the cationic fixing agent is mixed with the coating liquid for the glossy layer, the compatibility with the components contained in the glossy layer is poor. There is a problem that the liquid aggregates and there is a problem in stability, and the transparency and gloss of the coating layer film are lowered.

  The weight ratio of the fumed alumina particles to the cationic fixing agent is preferably 100: 0.3 to 100: 30, more preferably 100: 0.5 to 100: 20. If the ratio of the fumed alumina particles to the cationic fixing agent is less than 100: 0.3 by weight, the effect of the cationic fixing agent is difficult to obtain, and the color developability of the ink is poor. There is. In addition, since the fixability of the ink is inferior, there is also a problem that the ink oozes when it is wet or stored under high humidity. On the other hand, if the ratio of the fumed alumina particles to the cationic fixing agent is greater than 100: 30 by weight, the ink fixing property is good, but the ink absorbability is impaired, and the image density is low. In addition, the cationic component may cause an aggregating action with an anionic component of the ink, resulting in a problem that the sharpness of the image is impaired.

  The cationic fixing agent preferably contains at least one of epichlorohydrin-based or polyamine-based, dicyan-based, dimethyldiallylammonium chloride copolymer, and acrylamide-diallylamine hydrochloride copolymer. More preferred is an epichlorohydrin type from the viewpoints of ink absorbability, fixability, and image sharpness.

  The binder is preferably polyvinyl alcohol having a saponification degree of 80 to 99.9 mol% and a polymerization degree of 1500 to 4500, and more preferably polyvinyl alcohol having a saponification degree of 85 to 99 mol% and 2000 to 4000. If the degree of saponification is lower than 80, the glossy layer has good absorbency, but the water resistance is weak, and the coating layer film is peeled off by water (a phenomenon in which the coating layer film peels off the support when placed in water for a long time). There is a problem that occurs. When the degree of saponification is higher than 99.9 mol%, the water resistance is good and the water-resistant peeling of the coating layer film does not occur, but there is a problem that the ink absorption rate of the glossy layer becomes slow and the sharpness of the printed image is poor. . Here, the degree of saponification is expressed as a percentage of the number of hydroxyl groups in the total number of hydroxyl groups and acetic acid groups in polyvinyl alcohol.

  When the polymerization degree of polyvinyl alcohol is lower than 1500, the ink absorbability is good, but there is a problem that the strength of the coating film of the glossy layer is inferior and the surface is cracked. When the degree of polymerization is higher than 4500, the surface strength and cracks of the glossy layer are good, but there is a problem that the ink absorption rate is slow and the sharpness of the printed image is poor.

  As the support, paper or coated paper is used. Since it is cast, one having a high air permeability (JIS P 8117) is preferred so that water vapor can be easily removed from the back surface. The reason why the film or resin-coated paper having a high smoothness and a high glossiness is not used as the support is that it is considered that the finished product can be recycled or incinerated. The film can be regenerated when the raw material is PET. In other cases, however, regeneration is difficult and, of course, incineration is impossible. The same applies to resin-coated paper.

  The main components of the ink receiving layer are clay, silica, and hollow PP, and the clay: silica component ratio is preferably 5: 1 to 2: 1, and more preferably 4: 1 to 3: 1. When the clay ratio of the clay: silica component is larger than 5: 1, the smoothness and glossiness after casting are high, and the surface having high smoothness and glossiness is obtained even when a glossy expression layer is provided thereafter. can get. However, the ink absorbability deteriorates. When the clay: silica component ratio is greater than 2: 1, the ink absorption is good, but the smoothness and glossiness after casting are low, and even when a glossy layer is provided after that, smoothness is achieved. In addition, the surface quality is low. The component ratio of silica: hollow PP is preferably 2: 1 to 1: 2, more preferably 3: 2 to 2: 3. When the silica: hollow PP component ratio is greater than 2: 1, the bleeding in the print quality is good, but the print density is low. If the silica: hollow PP component ratio is larger than 1: 2, the printing density is good, but the bleeding is poor and the quality of the printed image is reduced.

The absolute dry coating amount of the ink receiving layer is preferably 5 to ²⁰ g / m ² , more preferably 8 to 17 g / m ² . When the absolute dry coating amount of the ink receiving layer is less than 5 g / m ² , there is a problem that ink absorbability is insufficient. If the absolute dry coating amount of the ink receiving layer is more than 20 g / m ² , the ink absorbency is good, but the coating property of the glossy layer is inferior, the cracking of the glossy layer is likely to occur, smoothness, glossiness, etc. There is a problem that the surface quality is inferior.

The absolute dry coating amount of the glossy layer is preferably 5 to 70 g / m ² , more preferably 20 to 50 g / m ² . When the absolute dry coating amount of the glossy layer is less than 5 g / m ² , there is a problem that the ink absorbability is insufficient and the ink overflows and bleeds. When the dry coating amount of the glossy layer is more than 70 g / m ² , the ink absorbability is good, but the glossy layer is liable to crack, causing a problem in image sharpness and unnecessarily dry coating. In terms of labor, the ink absorption effect is saturated, resulting in productivity and cost problems.

  The 75-degree specular gloss is preferably 40 to 95%, more preferably 50 to 90%. When the glossiness is lower than 40%, the visual glossiness is insufficient, and when the glossiness is higher than 95%, the glare feeling is strong and undesirable.

  The image clarity is preferably 40 to 98%, and more preferably 50 to 95%. When the image clarity is lower than 40%, the visual glossiness and sharpness are insufficient, and when the image clarity is higher than 98%, the glare feeling is strong and undesirable.

  It is preferable to disperse or dissolve the cationic fixing agent in a solvent containing water and a solvent, and apply it by applying a drying treatment after coating. That is, the cationic fixing agent can be uniformly applied onto the glossy layer by dispersing or dissolving in a solvent containing water and a solvent to prepare a liquid, coating and drying.

  The ink jet recording sheet of the present invention already has a high gloss when it is coated and dried. If necessary, high gloss can be imparted by calendar processing. The calendar process can be finished using a calendar device such as a machine calendar, a TG calendar, a super calendar, or a soft calendar.

  In order to improve the glossiness, the formation of the glossy expression layer may be further obtained by a casting process. In addition, in order to improve glossiness, the glossy expression layer mainly composed of fumed alumina particles of the present invention is formed by a manufacturing method in which the glossy expression layer is in a swollen state, a smooth film is adhered, peeled and removed, and mirror finished. May be obtained.

  Furthermore, for the glossy layer, as additives, dye fixing agents, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, penetrating agents, colored dyes, colored pigments, fluorescent whitening agents UV absorbers, antioxidants, antiseptics, antibacterial agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, curing agents, and the like can be appropriately blended.

  The method of applying or impregnating the glossy layer according to the present invention can be used in machines of various apparatuses such as various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain coaters and the like.

In order to impart curl aptitude, a back coat layer can be coated on the opposite side of the glossy layer side with the support interposed therebetween.

Example:

  Examples will be described below, but the present invention is not limited to these examples. In the examples, “parts” and “%” indicate parts by weight of absolute dry and parts by weight of absolute dry weight unless otherwise specified.

In the following examples and comparative examples, general high-quality paper (here, Kinmari SW127.9 g / m ² manufactured by Hokuetsu Paper Co., Ltd.) was used, and all were common.

[Forming an ink receiving layer]
The ink receiving layer was coated on the surface of the support by casting. The pigment dispersion for the ink-receiving layer coating composition (cast coating solution) was 64 parts of clay (UW-90: manufactured by Engelhard), synthetic amorphous silica (Mizukasil P-78A: Mizusawa Chemical Co., Ltd.). 16 parts) was used to prepare a solid content of 55%. In this dispersion, 16 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) and 15 parts of SBR latex (L-1970: manufactured by Asahi Kasei) are used, and the ratio of clay: silica is 4: 1. An ink receiving layer was obtained by a cast coating method using a cast coating solution having a silica: hollow PP ratio of 1: 1 and a solid content of 40%. The ink receiving layer was formed by coating on a support so that the dry coating amount was 12 g / m ^2, and pressing and drying for 10 seconds on a mirror roll maintained at a surface temperature of 100 ° C.
(Glossy expression layer is formed)
The gloss developing layer was coated on the surface of the ink receiving layer of the support on which the ink receiving layer was formed by casting. The glossy layer coating composition (coating solution) is fumed alumina particles (Cab-O-Sperse PG003: Cabot) as inorganic fine particles having an average particle size of 150 nm (measurement of particle size: by PCS method) of aggregates. Using 100 parts of Specialty Chemicals Inc.), 10 parts of polyvinyl alcohol (PVA-235: manufactured by Kuraray Co., Ltd.) having a saponification degree of 88 mol% and a polymerization degree of 3500, the mixture was prepared to a solid content of 20%. This coating solution was coated and dried so as to have an absolutely dry coating amount of 37 g / m ² . Further, a cationic fixing agent (Papiogen P-105: manufactured by Senka Co., Ltd.) is mixed with water and a solvent of isopropyl alcohol 1: 1 on the glossy layer to prepare a solid content of 3%. The ink jet recording sheet of the present invention was obtained by coating and drying to 1 g / m ² .

  In Example 1, it was carried out except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 8 parts, and the ratio of silica: hollow PP was 2: 1. In the same manner as in Example 1, an inkjet recording sheet of the present invention was obtained.

  In Example 1, it was carried out except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 32 parts, and the ratio of silica: hollow PP was 1: 2. In the same manner as in Example 1, an inkjet recording sheet of the present invention was obtained.

  In Example 1, the pigment dispersion for the ink-receiving layer coating composition was 66.7 parts of clay (UW-90: manufactured by Engelhard), synthetic amorphous silica (Mizukasil P-78A: Mizusawa Chemical Industries). 13.3 parts) was used to prepare a solid content of 55%. Except for using 13.3 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) for this dispersion, the clay: silica ratio was 5: 1, and the silica: hollow PP ratio was 1: 1. Obtained an ink jet recording sheet of the present invention in the same manner as in Example 1.

  In Example 4, except that the hollow PP (Rohpaque HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 6.7 parts, and the ratio of silica: hollow PP was 2: 1. In the same manner as in Example 4, an ink jet recording sheet of the present invention was obtained.

  In Example 4, except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 26.6 parts, and the ratio of silica: hollow PP was 1: 2. In the same manner as in Example 4, an ink jet recording sheet of the present invention was obtained.

  In Example 1, the pigment dispersion for the coating composition of the ink receiving layer was 53.3 parts of clay (UW-90: manufactured by Engelhard), synthetic amorphous silica (Mizukasil P-78A: Mizusawa Chemical Industries). 26.7 parts), and the mixture was adjusted to a solid content of 55%. Except for using 26.7 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) for this dispersion, the clay: silica ratio was 2: 1, and the silica: hollow PP ratio was 1: 1. Obtained an ink jet recording sheet of the present invention in the same manner as in Example 1.

  In Example 7, except that the hollow PP (Rohpaque HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 13.4 parts, and the ratio of silica: hollow PP was 2: 1. In the same manner as in Example 7, an ink jet recording sheet of the present invention was obtained.

  In Example 7, except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 53.4 parts, and the ratio of silica: hollow PP was 1: 2. In the same manner as in Example 7, an ink jet recording sheet of the present invention was obtained.

An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the absolute dry coating amount of the ink receiving layer was changed to 5 g / m ^{2 in} Example 1.

In Example 4, an ink jet recording sheet of the present invention was obtained in the same manner as in Example 4 except that the absolute dry coating amount of the ink receiving layer was changed to 5 g / m ² .

In Example 7, an ink jet recording sheet of the present invention was obtained in the same manner as Example 7 except that the absolute dry coating amount of the ink receiving layer was 5 g / m ² .

An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the absolute dry coating amount of the ink receiving layer was 20 g / m ^{2 in} Example 1.

In Example 4, an ink jet recording sheet of the present invention was obtained in the same manner as in Example 4 except that the absolute dry coating amount of the ink receiving layer was 20 g / m ² .

In Example 7, an ink jet recording sheet of the present invention was obtained in the same manner as in Example 7, except that the absolute dry coating amount of the ink receiving layer was 20 g / m ² .

An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the absolute dry coating amount of the glossy layer in Example 1 was changed to 5 g / m ² .

In Example 4, the ink jet recording sheet of the present invention was obtained in the same manner as Example 4 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 7, the inkjet recording sheet of the present invention was obtained in the same manner as Example 7 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 10, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 10 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 11, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 11 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 12, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 12 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 13, the inkjet recording sheet of the present invention was obtained in the same manner as Example 13 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 14, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 14 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 15, the inkjet recording sheet of the present invention was obtained in the same manner as in Example 15 except that the dry coating amount of the glossy layer was 5 g / m ² .

In Example 1, the ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the dry coating amount of the glossy layer was 70 g / m ² .

In Example 4, the inkjet recording sheet of the present invention was obtained in the same manner as in Example 4 except that the dry coating amount of the glossy layer was 70 g / m ² .

In Example 7, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 7, except that the absolute dry coating amount of the glossy layer was 70 g / m ² .

In Example 10, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 10 except that the dry coating amount of the glossy layer was 70 g / m ² .

In Example 11, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 11 except that the dry coating amount of the glossy layer was 70 g / m ² .

In Example 12, an inkjet recording sheet of the present invention was obtained in the same manner as in Example 12 except that the absolute dry coating amount of the glossy layer was 70 g / m ² .

In Example 13, an inkjet recording sheet of the present invention was obtained in the same manner as Example 13 except that the dry coating amount of the glossy layer was 70 g / m ² .

In Example 14, an inkjet recording sheet of the present invention was obtained in the same manner as Example 14 except that the dry coating amount of the glossy layer was 70 g / m ² .

In Example 15, the inkjet recording sheet of the present invention was obtained in the same manner as in Example 15 except that the dry coating amount of the glossy layer was 70 g / m ² .

Comparative Example 1:
In Example 1, an ink jet recording sheet was obtained in the same manner as in Example 1 except that the cationic fixing agent was not applied.

Comparative Example 2:
In Example 1, the pigment dispersion for the ink-receiving layer coating composition was 70 parts of clay (UW-90: Engelhard), synthetic amorphous silica (Mizukasil P-78A: manufactured by Mizusawa Chemical Co., Ltd.). ) 10 parts was used to prepare a solid content of 55%. This dispersion was carried out except that 10 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) was used, except that the ratio of clay: silica was 7: 1 and the ratio of silica: hollow PP was 1: 1. An ink jet recording sheet was obtained in the same manner as in Example 1.

Comparative Example 3:
Comparative Example 2 except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 5 parts, and the silica: hollow PP ratio was 2: 1. In the same manner as in Example 1, an ink jet recording sheet was obtained.

Comparative Example 4:
Comparative Example 2 except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 20 parts and the silica: hollow PP ratio was 1: 2. In the same manner as in Example 1, an ink jet recording sheet was obtained.

Comparative Example 5:
In Example 1, the pigment dispersion for the coating composition of the ink receiving layer was 40 parts of clay (UW-90: manufactured by Engelhard), synthetic amorphous silica (Mizukasil P-78A: manufactured by Mizusawa Chemical Co., Ltd.). ) 40 parts were used to prepare a solid content of 55%. This dispersion was carried out except that 40 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) was used, except that the ratio of clay: silica was 1: 1 and the ratio of silica: hollow PP was 1: 1. An ink jet recording sheet was obtained in the same manner as in Example 1.

Comparative Example 6:
Comparative Example 5 except that the hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was 20 parts and the silica: hollow PP ratio was 2: 1. In the same manner as in Example 4, an ink jet recording sheet was obtained.

Comparative Example 7:
Comparative Example 5 except that the ratio of silica: hollow PP was 1: 2 in Comparative Example 5 except that 80 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was used. In the same manner as in Example 4, an ink jet recording sheet was obtained.

Comparative Example 8:
In Example 1, the pigment dispersion for the coating composition of the ink receiving layer was 64 parts of clay (UW-90: manufactured by Engelhard), synthetic amorphous silica (Mizukasil P-78A: manufactured by Mizusawa Chemical Co., Ltd.). ) 16 parts were used to prepare a solid content of 55%. This dispersion was carried out except that 4 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) was used, except that the ratio of clay: silica was 4: 1 and the ratio of silica: hollow PP was 4: 1. An ink jet recording sheet was obtained in the same manner as in Example 1.

Comparative Example 9:
In Comparative Example 8, Comparative Example except that 64 parts of hollow PP (Ropeke HP-91: manufactured by Rohm and Haas) in the coating composition of the ink receiving layer was used, and the ratio of silica: hollow PP was 1: 4. In the same manner as in Example 7, an ink jet recording sheet was obtained.

Comparative Example 10:
An ink jet recording sheet was obtained in the same manner as in Example 1, except that the absolute dry coating amount of the ink receiving layer was 2 g / m ² .

Comparative Example 11:
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the absolute dry coating amount of the ink receiving layer was 30 g / m ² .

Comparative Example 12:
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the dry coating amount of the glossy layer in Example 1 was 2 g / m ² .

Comparative Example 13:
In Example 1, an ink jet recording sheet was obtained in the same manner as in Example 1 except that the dry coating amount of the glossy layer was 80 g / m ² .

[Evaluation methods]
Surface quality evaluation and printing evaluation were performed on the ink jet recording sheets obtained in Examples 1 to 33 and Comparative Examples 1 to 12. The strength of the coating film, surface cracks, glossiness, glossiness, image clarity, image sharpness, ink absorbency, and print density were evaluated by the following methods. The print image clarity, ink absorbency, and print density were evaluated by recording with a PM-950C machine manufactured by Epson, which is an ink jet printer for dye ink. The results obtained are shown in Table 1, Table 2 and Table 3.

“Strength of coating film” The coated surface was rubbed with a finger to evaluate the powder fall off.
(Double-circle): There is no powder fall of a coating surface, it does not adhere to a finger | toe, and is very favorable.
◯: Less powder falling on the coated surface, good adhesion to fingers and good.
Δ: There was a slight powder fall off of the coated surface, and a little adhered to the finger.
X: There is much powder fallen of the coating surface, and it has also adhered to the finger | toe.

“Surface crack” The surface crack was evaluated by visual observation.
A: There is no crack on the coated surface, and the surface quality is very good.
○: There are few cracks on the coated surface and the surface quality is good.
(Triangle | delta): There are some cracks of the coating surface, and surface quality is not so good.
X: There are many cracks on the coated surface and the surface quality is poor.

“Glossiness” was visually evaluated according to the following evaluation criteria. A: Glossiness visually felt is very high and very good.
○: The gloss feeling visually felt is high and good.
(Triangle | delta): The gloss perceived visually is a little low and is not so favorable.
X: The glossiness visually felt is low and bad.

  The “glossiness” of the white background portion of the inkjet recording sheet was measured with a gloss meter (GM-26D, manufactured by Murakami Color Research Laboratory Co., Ltd.) according to the method of JIS P8142.

“Image clarity” The image clarity of an incident angle of 60 degrees and a comb width of 2 mm was measured with a image clarity measuring device (ICM-1T, manufactured by Suga Test Instruments Co., Ltd.) in accordance with the method of JIS H8866. did.

“Image sharpness” Printed with a PM-950C machine, the printed image was visually evaluated for sharpness.
A: The printed image is very clear and the contrast is clear.
○: The printed image is clear and has contrast.
Δ: The printed image is clear but the contrast is not so clear and the image is slightly white blurred.
X: Printed image is not clear and white blur.

“Ink absorbability” Ink absorbability is evaluated by attaching high quality paper to the printed surface printed every 5 seconds immediately after printing and observing whether the ink is transferred to the high quality paper. Measure the time until no transfer at all. The measured number of seconds was evaluated in four stages as follows.
A: No transfer at all within 5 seconds immediately after printing.
○: No transfer at all in 5 seconds or more and less than 10 seconds.
(Triangle | delta): The thing which is not transcribed at all within 10 to less than 30 seconds.
X: Transferred even after 30 seconds.

“Print density” The print density of the solid black portion was measured with a reflection densitometer (manufactured by Dainippon Screen, DM-400). If the print density is 1.65 or more, there is no practical problem.

As is apparent from the results of Tables 1 to 6, in the examples of the present invention, an ink receiving layer coated on a support by a casting process, and a recording medium provided with a gloss developing layer on the ink receiving layer The ink receiving layer is mainly composed of clay, silica and hollow plastic pigment, the ratio of clay: silica is 5: 1 to 2: 1, and the ratio of silica: hollow plastic pigment is 2: 1 to 1: 2, the dry coating amount of the ink receiving layer is 5 to 20 g / m ² , the dry coating amount of the gloss developing layer is 5 to 70 g / m ² , and the gloss developing layer is a primary particle. Composed of fumed alumina particles having an average particle diameter of 80 to 300 nm and a binder, and the ratio of fumed alumina particles to binder is 100: 3 to 100: 30 by weight ratio, Gloss An ink jet recording sheet characterized by comprising imparting a cationic fixing agent onto the current layer. Further, it includes that the 75 degree specular gloss specified in JIS P 8142 is 40 to 95% or the image clarity specified in JIS H 8686 is 40 to 98%. Examples are preferred as inkjet recording sheets. Comparative Examples 1 to 13 deviate from the above conditions, and are not preferable as inkjet recording sheets having good ink absorbability, clear recorded images, and excellent gloss.

Claims (2)

An ink receiving layer coated by casting on a support, and a recording medium provided with a glossy expression layer on the ink receiving layer, the ink receiving layer comprising clay, silica and a hollow plastic pigment as main components, The ratio of clay: silica is 5: 1 to 2: 1, the ratio of silica: hollow plastic pigment is 2: 1 to 1: 2, and the dry coating amount of the ink receiving layer is 5 to 20 g / m. ² and the gloss-developing layer has an absolute dry coating amount of 5 to 70 g / m ² , and the gloss-developing layer is composed of aggregates of primary particles, and the fumed particles having an average particle diameter of 80 to 300 nm of the aggregates. It is composed of alumina particles and a binder, and the ratio of the fumed alumina particles to the binder is 100: 3 to 100: 30 by weight, and a cationic fixing agent is provided on the glossy layer. Ink jet recording sheet. The inkjet according to claim 1, wherein the 75-degree specular gloss specified in JIS P 8142 is 40 to 95%, or the image clarity defined in JIS H8 686 is 40 to 98%. Recording sheet.