Recording medium

Abstract

To provide a recording medium capable of recording an image high in optical density, by maintaining uneven feeling of a base material in a solid printing part and by suppressing unevenness, even when an aqueous dye ink is used.SOLUTION: A recording medium comprising an absorbent substrate and an ink receiving layer provided on the absorbent substrate. The dry coating amount of the ink receiving layer is 6.0 g / m2 or larger and 11.0 g / m2 or smaller, and the arithmetic mean roughness Ra1(μm) of the surface of the absorbent substrate satisfies the relation of the following equation (1), arithmetic mean roughness Ra1, and arithmetic mean roughness Ra2(μm) on the surface of ink receiving layer satisfy the relation of the following formula (2), and an average length RSm1 (mm) of a roughness curve element of the surface of the absorbent substrate, and an average length RSm2 (mm) of the roughness curve element of the surface of the ink receiving layer satisfy the relation of the following formula (3). Ra1≥5.0 μm (1) Ra2 / Ra1≥0.87 (2) RSm2 / RSm1≤1.40 (3)SELECTED DRAWING: None

Description

[Technology Field]

[0001] A bracket relating to a recording medium. [Background technology]

[0002] Among recording media used in inkjet recording methods and other applications, there are matte-finish recording media with reduced gloss, offering a calm and deep appearance. One known method for obtaining such matte-finish recording media is to use inorganic particles with a large secondary particle size. In recent years, among matte-finish recording media, there has been a demand for recording media with an uneven surface, such as art paper. For such recording media, it is required that the uneven surface of the substrate is reflected in the image recording surface (printing area), that unevenness caused by the unevenness does not occur in the image, and that it is possible to record images with high optical density and excellent color reproduction.

[0003] As a matte-finish recording medium suitable for recording painting-like or calligraphic images, for example, an inkjet recording medium having an ink-receiving layer in which the surface roughness, center-line average roughness, and Wang-Ren smoothness are controlled within a specific numerical range has been proposed (Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-287440 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] When images were recorded on the recording medium proposed in Patent Document 1 using aqueous pigment ink, it was found that images with a certain level of optical density could be recorded. However, it was found that when using aqueous dye ink, it is difficult to record images with the high level of optical density required in recent years.

[0006] Therefore, the object of the present invention is to provide a recording medium that can record high optical density images in which the unevenness of the substrate in the solid printing area is maintained and unevenness is suppressed, even when using water-based dye ink. [Means for solving the problem]

[0007] The above objective is achieved by the present invention as follows: According to the present invention, a recording medium having an absorbent substrate and an ink receiving layer provided on the absorbent substrate containing inorganic particles and a binder, wherein the dry coating amount of the ink receiving layer is 6.0 g / m². 2 More than 11.0g / m 2 A recording medium is provided, characterized in that the arithmetic mean roughness Ra1 (μm) of the surface of the absorbent substrate as defined in ISO 4287:1997 satisfies the relationship of formula (1) below, the arithmetic mean roughness Ra1 and the arithmetic mean roughness Ra2 (μm) of the surface of the ink receiving layer as defined in ISO 4287:1997 satisfy the relationship of formula (2) below, and the average length RSm1 (mm) of the roughness curve elements of the surface of the absorbent substrate as defined in ISO 4287:1997 and the average length RSm2 (mm) of the roughness curve elements of the surface of the ink receiving layer as defined in ISO 4287:1997 satisfy the relationship of formula (3) below. Ra1 ≥ 5.0 μm ···(1) Ra2 / Ra1≧0.87 ···(2) RSm2 / RSm1 ≤ 1.40 ···(3) [Effects of the Invention]

[0008] According to the present invention, even when using water-based dye ink, it is possible to provide a recording medium that can record images with high optical density while maintaining the unevenness of the substrate in the solid printing area and suppressing unevenness. [Modes for carrying out the invention]

[0009] <Recording medium> The present invention will be described in more detail below with reference to preferred embodiments. Hereinafter, the inkjet recording medium will also be simply referred to as the "recording medium." The inventors diligently studied to provide a recording medium capable of recording high optical density images in which the unevenness of the substrate in the solid printing area is maintained and unevenness is suppressed, even when using aqueous dye ink. As a result, they found that the above objective can be achieved by the following configuration, and thus completed the present invention. That is, the recording medium of the present invention is a recording medium suitable for inkjet use, having an absorbent substrate and an ink-receiving layer provided on the absorbent substrate containing inorganic particles and a binder. The arithmetic mean roughness Ra1 (μm) of the surface of the absorbent substrate, measured in accordance with ISO 4287:1997, satisfies the relationship of formula (1) below. Ra1 ≥ 5.0 μm ···(1)

[0010] By setting the arithmetic mean roughness Ra1 of the surface of the absorbent substrate to 5.0 μm or more, even when an ink-receiving layer is provided on this absorbent substrate, a recording medium with a rough surface texture exhibiting clear irregularities can be obtained. If the arithmetic mean roughness Ra1 of the surface of the absorbent substrate is less than 5.0 μm, clear irregularities will not appear on the surface of the ink-receiving layer provided on the absorbent substrate, and a recording medium with a rough surface texture cannot be obtained. Furthermore, there is no particular upper limit to the arithmetic mean roughness Ra1 of the surface of the absorbent substrate, but it is preferable, for example, to be 10.0 μm or less.

[0011] The arithmetic mean roughness Ra1 mentioned above, and the arithmetic mean roughness Ra2 (μm) of the surface of the ink receiving layer as defined in ISO 4287:1997, satisfy the relationship given by equation (2) below. Ra2 / Ra1≧0.87 ···(2)

[0012] The ink receiving layer can usually be disposed on the absorbent substrate by drying a coating layer formed by coating a coating liquid for the ink receiving layer on the absorbent substrate. It is affected by factors such as the size of the absorbent substrate, the concentration, viscosity, and coating amount of the coating liquid, and the drying conditions of the coating layer. However, the arithmetic mean roughness Ra2 of the surface of the ink receiving layer is controlled within a range approximately similar to the arithmetic mean roughness Ra1 of the surface of the absorbent substrate. When the value of "Ra2 / Ra1" is 0.87 or more, the surface irregularities of the absorbent substrate generally follow the surface irregularities of the ink receiving layer, and almost no difference in thickness occurs within the ink receiving layer. Therefore, even when ink is applied to the ink receiving layer of the recording medium, almost no density difference occurs within the ink receiving layer, and a uniform image without unevenness can be recorded.

[0013] When the value of "Ra2 / Ra1" is less than 0.87, the surface irregularities of the ink receiving layer do not sufficiently follow the surface irregularities of the absorbent substrate. Therefore, the ink receiving layer at the location corresponding to the convex portion of the absorbent substrate is thin, and the ink receiving layer at the location corresponding to the concave portion of the absorbent substrate is thick. Therefore, when ink is applied to the ink receiving layer of such a recording medium, density unevenness occurs within the ink receiving layer, and a uniform image without unevenness cannot be recorded. The arithmetic mean roughness Ra1 of the surface of the absorbent substrate and the arithmetic mean roughness Ra2 of the surface of the ink receiving layer preferably satisfy the relationship of the following formula (6). Thereby, a more uniform image with further reduced unevenness can be recorded. 0.91≦Ra2 / Ra1≦1.05 ···(6)

[0014] Also, the arithmetic mean roughness Ra2 of the surface of the ink receiving layer is not particularly limited as long as it satisfies the relationship of the above formula (2), but for example, it is preferably 4.4 μm or more and 10.5 μm or less. When the ink receiving layer has two or more layers, the arithmetic mean roughness Ra2 of the surface of the ink receiving layer in the present invention means the arithmetic mean roughness of the surface of the ink receiving layer which is the outermost layer existing at the position farthest from the substrate.

[0015] The average length RSm1 (mm) of the roughness curve elements defined by ISO 4287:1997 on the surface of the absorbent substrate and the average length RSm2 (mm) of the roughness curve elements defined by ISO 4287:1997 on the surface of the ink receiving layer satisfy the relationship of the following formula (3). RSm2 / RSm1 ≦ 1.40 ···(3)

[0016] Although it is affected by the size of the absorbent substrate, the concentration, viscosity, and coating amount of the coating liquid, the drying conditions of the coating layer, etc., the average length RSm2 of the roughness curve elements of the ink receiving layer is controlled within a range approximately approximating the average length RSm1 of the roughness curve elements on the surface of the absorbent substrate. When the value of "RSm2 / RSm1" is 1.40 or less, the surface irregularities of the absorbent substrate generally follow the surface irregularities of the ink receiving layer, and almost no difference in thickness occurs within the ink receiving layer. Therefore, even when ink is applied to the ink receiving layer of the recording medium, almost no density difference occurs within the ink receiving layer, and a uniform image without unevenness can be recorded.

[0017] When the value of "RSm2 / RSm1" exceeds 1.40, a mismatch occurs between the period of the surface irregularities of the ink receiving layer and the period of the surface irregularities of the absorbent substrate, and the difference in thickness within the ink receiving layer becomes excessively large. Therefore, when ink is applied to the ink receiving layer of such a recording medium, density unevenness occurs within the ink receiving layer, and a uniform image without unevenness cannot be recorded. The average length RSm1 of the roughness curve elements on the surface of the absorbent substrate and the average length RSm2 of the roughness curve elements on the surface of the ink receiving layer preferably satisfy the relationship of the following formula (7). Thereby, a more uniform image with further reduced unevenness can be recorded. 0.95 ≦ RSm2 / RSm1 ≦ 1.30 ···(7)

[0018] The average length RSm1 of the roughness curve elements on the surface of the absorbent substrate is not particularly limited as long as it satisfies the relationship of the above formula (3), but for example, it is preferably 0.20 mm or more and 0.60 mm or less. Also, the average length RSm2 of the roughness curve elements on the surface of the ink receiving layer is not particularly limited as long as it satisfies the relationship of the above formula (3), but for example, it is preferably 0.28 mm or more and 0.78 mm or less.

[0019] The dry coating amount of the ink receiving layer is 6.0 g / m 2 or more and 11.0 g / m 2 or less, and preferably 7.0 g / m 2 or more and 10.0 g / m 2 or less. By setting the dry coating amount of the ink receiving layer within the above range, it is possible to obtain a recording medium capable of recording an image with a high optical density while maintaining the unevenness of the substrate in the solid printed portion and suppressing unevenness. If the dry coating amount is less than 6.0 g / m 2 , it becomes difficult to sufficiently cover the surface of the absorbent substrate with large unevenness. Therefore, the coated portion and the uncoated portion of the absorbent substrate coexist, resulting in unevenness in the recorded image. On the other hand, if the dry coating amount exceeds 11.0 g / m 2 , the absorbent substrate will be overly coated. For this reason, the unevenness on the surface of the absorbent substrate does not clearly appear, making it difficult to obtain the unevenness of the substrate. Also, since the ink receiving layer becomes too thick, it is impossible to increase the optical density of the image recorded with aqueous dye ink.

[0020] (Absorbent substrate) The "absorbent substrate" in this specification has a cob water absorption of 5.0 g / m after 30 seconds measured according to ISO 535:1991. 2The above refers to the base material. Any base material can be used as long as it satisfies the above-mentioned cob water absorption requirements. Examples of absorbent base materials include cast-coated paper, baryta paper, unsized paper with appropriate sizing, coated paper, and cotton paper. Among these, cotton paper is preferred as the absorbent base material from the viewpoint of texture and other factors. By using an absorbent base material, it is possible to create a recording medium that exhibits sufficient absorbency even with a small amount of coating liquid (coating amount) used to form the ink-receiving layer, and it is also possible to provide an ink-receiving layer without impairing the surface texture of the absorbent base material.

[0021] (Ink-receiving layer) The ink-receiving layer provided on the absorbent substrate contains inorganic particles and a binder. The ink-receiving layer can typically be formed on the absorbent substrate by coating it with a coating solution containing the materials for the ink-receiving layer, and then drying the resulting coating layer. That is, the materials for the ink-receiving layer are generally the same as the materials for the coating solution used for the ink-receiving layer.

[0022] In the ink-receiving layer, the ratio of the inorganic particle content P to the binder content B (P / B ratio) is preferably between 100 / 30 and 100 / 70. By setting the P / B ratio within the above range, sufficient strength can be imparted to the ink-receiving layer, and the color development of the image and the ink absorption can be improved.

[0023] The ink-receiving layer may be a single layer or two or more layers. However, when two or more ink-receiving layers are provided, it is preferable to apply two or more coating solutions simultaneously. When the ink-receiving layers are provided sequentially, the coating solution for the second ink-receiving layer will be applied on top of the first ink-receiving layer. In this case, the absorption and drying conditions of the coating solution will vary considerably, which may make it somewhat difficult to form an ink-receiving layer with the desired uneven texture.

[0024] [Inorganic particles] The average secondary particle diameter of the inorganic particles is preferably 3.0 μm or larger. By using inorganic particles with an average secondary particle diameter of 3.0 μm or larger, an ink-receiving layer with a more matte surface texture can be formed. There is no particular upper limit on the average secondary particle diameter of the inorganic particles, but for example, it is preferably 15.0 μm or smaller. In this specification, "average secondary particle diameter" of inorganic particles refers to the volume-based cumulative 50% particle diameter (D50) measured by laser diffraction.

[0025] As inorganic particles, white pigments such as silica, alumina, and light calcium carbonate can be used. Among these, amorphous silica is preferred. Amorphous silica may be produced by any method. Methods for producing amorphous silica include dry methods and wet methods. Dry methods are broadly classified into combustion methods and heating methods. Wet methods, on the other hand, are broadly classified into precipitation methods and gelation methods.

[0026] The combustion method, a type of dry process, is also called the gas phase method. It involves burning a mixture of vaporized silicon tetrachloride and hydrogen in air at 1,500 to 2,000°C to produce amorphous silica.

[0027] The precipitation method, a type of wet process, involves reacting sodium silicate with sulfuric acid or the like in an aqueous solution to obtain amorphous silica as a precipitate. In this precipitation method, the primary particle size of the resulting amorphous silica can be adjusted by controlling conditions such as reaction temperature and acid addition rate. Furthermore, the secondary particle size of the resulting amorphous silica can also be adjusted by controlling drying and grinding conditions.

[0028] The gelation method, one of the wet processes, is a method for obtaining amorphous silica by simultaneously adding sodium silicate and sulfuric acid. This gelation method allows for the production of amorphous silica with a three-dimensional hydrogel structure, where polymerization of silica particles progresses through the dehydration condensation of silanol groups. Furthermore, amorphous silica produced by the gelation method has a relatively small hydrogel structure, resulting in a larger specific surface area compared to amorphous silica produced by the precipitation method. Among these methods, the use of amorphous silica produced by the gelation method is preferred.

[0029] The inorganic particles preferably include a first amorphous silica and a second amorphous silica. The first amorphous silica and the second amorphous silica have different average secondary particle diameters. Preferably, the arithmetic mean roughness Ra1 (μm) of the surface of the absorbent substrate and the average secondary particle diameter D1 (μm) of the first amorphous silica satisfy the relationship shown in formula (4) below. Furthermore, preferably, the arithmetic mean roughness Ra1 (μm) of the surface of the absorbent substrate and the average secondary particle diameter D2 (μm) of the second amorphous silica satisfy the relationship shown in formula (5) below. By satisfying the relationships shown in formulas (4) and (5) below, the color development of images recorded with aqueous dye ink can be further enhanced. The mixing ratio (mass ratio) of the first amorphous silica and the second amorphous silica is preferably such that the content of the first amorphous silica : the content of the second amorphous silica = 30:70 to 70:30. D1 ≤ Ra1 ···(4) D2≧Ra1 ···(5)

[0030] The oil absorption capacity of amorphous silica, measured in accordance with JIS K6217-4:2017, is preferably 150 mL / 100g or more and 350 mL / 100g or less, and more preferably 180 mL / 100g or more and 330 mL / 100g or less. The pore volume of amorphous silica measured by the BET method is preferably 1.0 mL / g or more, and more preferably 1.3 mL / g or more. Furthermore, the specific surface area of ​​amorphous silica measured by the BET method is 200 m². 2 / g or more 500m 2 It is preferable that the value be less than or equal to / g.

[0031] [Binder] Examples of binders include polyvinyl alcohol (PVA), oxidized starch, etherified starch, phosphated starch, carboxymethylcellulose, hydroxyethylcellulose, casein, gelatin, soy protein, polyvinylpyrrolidone, maleic anhydride resin, conjugated polymer latex such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer, acrylic polymer latex such as polymers of acrylic acid esters and methacrylic acid esters, vinyl polymer latex such as ethylene-vinyl acetate copolymer, melamine resin, urea resin, (co)polymer resins of acrylic acid esters and methacrylic acid esters such as polymethyl methacrylate, polyurethane resin, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, and alkyd resin.

[0032] The above-mentioned binders can be used individually or in combination of two or more. Among these, polyvinyl alcohol (PVA) is preferred as the binder. The average degree of polymerization of the PVA is preferably 1,500 to 5,000. The degree of saponification of the PVA is preferably 70% to 100%. Modified PVA, such as silanol-modified PVA having silanol groups at its ends, can also be used as the binder.

[0033] [Additives] The ink-receiving layer and the coating solution for the ink-receiving layer may contain additives such as pigment dispersants, fastness enhancers, and surfactants as appropriate. In particular, it is preferable to include a cationic polymer in the coating solution for the ink-receiving layer because it can improve the dispersibility of the coating solution and improve the fastness and water resistance of the recorded image. Examples of cationic polymers include polymers having primary to tertiary amino groups in their molecules and polymers having quaternary ammonium bases. Examples of cationic polymers include polyalkylene polyamines, derivatives of polyalkylene polyamines, dicyanide cationic resins, polyamine cationic resins, epichlorohydrin-dimethylamine addition polymers, dimethyldiallylammonium coloride polymers, and diallylamine salt polymers.

[0034] The amount of additives in the ink receiving layer and the coating solution for the ink receiving layer is preferably 0.1 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of inorganic particles such as amorphous silica.

[0035] (Method of manufacturing recording medium) The method for manufacturing the recording medium described above is not particularly limited. For example, it is preferable to manufacture the recording medium by a manufacturing method that includes a step of preparing a coating solution for the ink receiving layer (coating solution preparation step) and a step of applying the prepared coating solution to an absorbent substrate (coating step).

[0036] In the coating solution preparation process, a coating solution for the ink receiving layer is prepared. The coating solution can be prepared by mixing the aforementioned components according to a standard method.

[0037] In the coating process, the prepared coating solution is applied to the absorbent substrate to form a coating layer. A gate roll coater, size press, bar coater, blade coater, air knife coater, roll coater, brush coater, curtain coater, gravure coater, spray device, etc., can be used to apply the coating solution to the absorbent substrate. Alternatively, the coating solution may be applied after being appropriately heated.

[0038] It is preferable to dry the coating layer formed by applying the coating liquid to an absorbent substrate. To dry the coating layer, hot air dryers such as straight tunnel dryers, arch dryers, air loop dryers, and sine curve air float dryers can be used. Dryers using infrared rays, heating dryers, microwaves, etc., can also be used. The heating temperature during drying can be, for example, 80 to 130°C.

[0039] Before applying the coating solution to the absorbent substrate, a surface treatment solution containing a surface treatment agent may be applied to the surface of the absorbent substrate (the surface to which the coating solution will be applied). By applying the surface treatment solution to the surface of the absorbent substrate in advance, the wettability of the coating solution to the absorbent substrate is increased, and the adhesion between the formed ink-receiving layer and the absorbent substrate can be improved. Examples of surface treatment agents include thermoplastic resins such as acrylic resins, polyurethane resins, polyester resins, polyethylene resins, polyvinyl chloride resins, polypropylene resins, polyamide resins, and styrene-butadiene copolymers; silane coupling agents; and the like. The surface treatment solution may optionally contain inorganic particles such as titanium dioxide, calcium carbide, silica, and alumina.

[0040] <Image recording method> Images can be recorded on the recording medium by ejecting ink from an inkjet recording head and applying it to the recording medium. Methods for ejecting ink include methods that eject ink by applying mechanical energy to the ink, and methods that eject ink by applying thermal energy to the ink. As for the ink, water-based inks containing dyes as colorants (water-based dye inks) and water-based inks containing pigments as colorants (water-based pigment inks) can be used. Among these, the use of water-based dye inks is preferred. [Examples]

[0041] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way by the following examples unless it exceeds the gist of the invention. Unless otherwise specified, amounts of components expressed in "parts" and "%" are based on mass.

[0042] <Manufacturing of absorbent materials> (Absorbent substrates A, B, and C) Water was added to the paper pulp with the composition shown below to adjust the solid content to 3.0%. "CSF" stands for Canadian Standard Freeness. [Paper material] • Cotton linter pulp with a filtration efficiency of 330 mLCSF: 100 parts • Cationized starch: 0.6 parts • Heavy calcium carbonate: 10 parts • Light calcium carbonate: 15 parts • Alkyl ketene dimer: 0.2 parts • Cationic polyacrylamide: 0.05 parts

[0043] Next, the paper was prepared using a long-wire paper machine, followed by a three-stage wet press, and then dried in a multi-cylinder dryer. A size press was used, and the solid content was 1.0 g / m². 2 The material was impregnated with an aqueous solution of oxidized starch and dried. Afterward, it underwent machine calendering to achieve a basis weight of 150 g / m². 2 An absorbent substrate A was obtained with an arithmetic mean roughness Ra1 = 6.6 (μm) and an average length of roughness curve elements RSm1 = 0.31 (mm) as specified in ISO 4287:1997. The water absorption of the obtained absorbent substrate A after 30 seconds, measured in accordance with ISO 535:1991, was 25 g / m². 2 That was the case.

[0044] Furthermore, by appropriately changing the pressing and calendering conditions, absorbent substrate B with Ra1 = 5.1 (μm) and RSm1 = 0.29 (mm) and absorbent substrate C with Ra1 = 4.4 (μm) and RSm1 = 0.25 (mm) were obtained. The resulting water absorption of absorbent substrates B and C was 23 g / m², respectively. 2and 22g / m 2 That was the case.

[0045] (Absorbent base material D) Water was added to the paper pulp with the composition shown below to adjust the solid content to 3.0%. [Paper material] • Hardwood bleached kraft pulp (LBKP) with a filtration rate of 450 mLCSF: 80 parts • 20 parts of bleached coniferous kraft pulp (NBKP) with a filtration rate of 480 mLCSF. • Cationized starch: 0.6 parts • Heavy calcium carbonate: 10 parts • Light calcium carbonate: 15 parts • Alkyl ketene dimer: 0.1 part • Cationic polyacrylamide: 0.03 parts

[0046] Next, the paper was prepared using a long-wire paper machine, followed by a three-stage wet press, and then dried in a multi-cylinder dryer. A size press was used, and the solid content was 1.0 g / m². 2 The material was impregnated with an aqueous solution of oxidized starch and dried. Afterward, it underwent machine calendering to achieve a basis weight of 150 g / m². 2 An absorbent substrate D was obtained with an arithmetic mean roughness Ra1 = 6.6 (μm) and an average roughness curve element length RSm1 = 0.31 (mm), measured in accordance with ISO 4287:1997. The resulting absorbent substrate D had a cob water absorption of 23 g / m². 2 That was the case.

[0047] <Manufacturing of recording media> (Preparation of dispersions A and B) A dispersant solution was obtained by adding 10 parts of a dispersant (product name "Sharol DC-902", manufactured by Daiichi Kogyo Seiyaku) to pure water in an amount equal to 100 parts of silica. To the obtained dispersant solution, amorphous silica A (product name "Nipgel AY-603", manufactured by Tosoh Silica, D50: 10 μm) was added in an amount equal to 19% solid content, and the mixture was thoroughly stirred with a stirrer to obtain a dispersion. The obtained dispersion was appropriately diluted with pure water to obtain dispersion A with a solid content concentration of 18% amorphous silica powder.

[0048] Furthermore, dispersion B with a solid content concentration of 18% was obtained in the same manner as in dispersion A described above, except that amorphous silica B (product name "Gasil 23F", manufactured by PQ Corporation, D50: 6 μm) was used instead of amorphous silica A.

[0049] (Preparation of coating solutions A and B for the ink receiving layer) Polyvinyl alcohol (product name "PVA235", manufactured by Kuraray) was dissolved in ion-exchanged water to obtain an aqueous PVA solution with a solid content of 8%. Dispersion A, dispersion B, and the aqueous PVA solution were mixed so that the mass ratio of amorphous silica A:amorphous silica B:binder (PVA) was 50:50:40. Pure water was added and stirred to obtain coating solution A for the ink receiving layer, resulting in a total solid content of 13%.

[0050] Furthermore, coating solution B for the ink receiving layer was obtained in the same manner as for coating solution A described above, except that dispersion A and the PVA aqueous solution were mixed so that the mass ratio of amorphous silica A to binder (PVA) was 100:40 (dispersion B was not used).

[0051] (Recording medium 1) Dry coating weight is 10.0 g / m² 2 A coating liquid A was applied to an absorbent substrate A to form a coating layer. The formed coating layer was dried with hot air at 100°C to form an ink receiving layer, and a recording medium 1 was obtained.

[0052] (Recording medium 2) Dry coating weight is 11.0 g / m² 2 Recording medium 2 was obtained in the same manner as in the case of recording medium 1 described above, except that coating solution A was applied in such a manner.

[0053] (Recording medium 3) Dry coating weight is 10.5 g / m² 2 Recording medium 3 was obtained in the same manner as in the case of recording medium 1 described above, except that coating solution A was applied in such a manner.

[0054] (Recording medium 4) Dry coating weight: 7.0 g / m²2 Recording medium 4 was obtained in the same manner as in the case of recording medium 1 described above, except that coating solution A was applied in such a manner.

[0055] (Recording medium 5) Dry coating weight: 8.0 g / m² 2 Recording medium 5 was obtained in the same manner as in the case of recording medium 1 described above, except that coating solution A was applied in such a manner.

[0056] (Recording medium 6) Dry coating weight: 9.0 g / m² 2 A recording medium 6 was obtained in the same manner as in the case of recording medium 1 described above, except that coating liquid A was applied in such a manner, and the coating layer was dried with hot air at 110°C to form an ink receiving layer.

[0057] (Recording medium 7) Dry coating weight is 12.0 g / m² 2 A recording medium 7 was obtained in the same manner as in the case of recording medium 6 described above, except that coating solution A was applied in such a manner.

[0058] (Recording medium 8) Dry coating weight is 10.0 g / m² 2 A recording medium 8 was obtained in the same manner as in the case of recording medium 6 described above, except that coating solution A was applied in such a manner.

[0059] (Recording medium 9) Dry coating weight is 11.0 g / m² 2 A recording medium 9 was obtained in the same manner as in the case of recording medium 6 described above, except that coating solution A was applied in such a manner.

[0060] (Recording medium 10) The recording medium 10 was obtained in the same manner as in the case of the recording medium 6 described above, except that the coating layer was dried with hot air at 90°C to form an ink receiving layer.

[0061] (Recording medium 11) The recording medium 11 was obtained in the same manner as in the case of the recording medium 6 described above, except that the coating layer was dried with hot air at 80°C to form an ink receiving layer.

[0062] (Recording medium 12) The recording medium 12 was obtained in the same manner as in the case of the recording medium 6 described above, except that the coating layer was dried with hot air at 70°C to form an ink receiving layer.

[0063] (Recording medium 13) Dry coating weight is 9.5 g / m² 2 Recording medium 13 was obtained in the same manner as in the case of recording medium 1 described above, except that coating solution A was applied in such a manner.

[0064] (Recording medium 14) Recording medium 14 was obtained in the same manner as in the case of recording medium 1 described above, except that coating liquid B was used instead of coating liquid A.

[0065] (Recording medium 15) Recording medium 15 was obtained in the same manner as in the case of recording medium 1 described above, except that absorbent substrate D was used instead of absorbent substrate A.

[0066] (Recording medium 16) Dry coating weight: 6.0 g / m² 2 Recording medium 16 was obtained in the same manner as in the case of recording medium 1 described above, except that coating liquid A was applied in such a manner.

[0067] (Recording medium 17) Dry coating weight is 5.0 g / m² 2 Recording medium 17 was obtained in the same manner as in the case of recording medium 1 described above, except that coating solution A was applied in such a manner.

[0068] (Recording medium 18) A recording medium 18 was obtained in the same manner as in the case of recording medium 1 described above, except that absorbent substrate C was used instead of absorbent substrate A.

[0069] (Recording medium 19) A recording medium 19 was obtained in the same manner as in the case of recording medium 1 described above, except that absorbent substrate B was used instead of absorbent substrate A.

[0070] Table 1 shows the details of the obtained recording media.

[0071]

[0072] <Rating> (Image recording) Using an inkjet recording device (product name "PIXUS TS6030", manufactured by Canon), images with (R,G,B)=(0,0,0) (solid print areas) were recorded on recording media 1 to 19 in "swelling paper" mode. The ink used was the genuine water-based dye ink (product name "BCI-351", manufactured by Canon, black (Bk) ink) of the above inkjet recording device.

[0073] (Evaluation of unevenness in solid print areas) The recorded images (solid print areas) were visually observed, and the unevenness in the solid print areas was evaluated according to the evaluation criteria shown below. Unevenness in the solid print areas refers to unevenness (non-uniformity) in print density. The results are shown in Table 2. In the evaluation criteria shown below, "A," "B," and "C" were considered desirable levels, and "D" was considered an unacceptable level. A: The level of unevenness was almost non-existent. B: The level of unevenness was only slightly noticeable. C: Some unevenness was observed, but it was at a level that did not pose any practical problems. D: There was a noticeable level of unevenness.

[0074] (Evaluation of the texture in solid print areas) The recorded images (solid print area) and blank paper area were visually observed, and the texture of the solid print area was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. In the evaluation criteria shown below, "A" and "B" were considered desirable levels, and "C" was considered an unacceptable level. A: The texture of the solid print area and the blank paper area were almost the same. B: The texture of the solid print area is slightly less pronounced compared to the blank area, but it is still at an acceptable level. C: The texture and feel of the solid print area were significantly diminished compared to the blank area.

[0075] (Evaluation of dye color development) After recording the images, they were stored for two days in an environment of 25°C and 50% RH (relative humidity). Subsequently, the OD value (optical density) of the images was measured using a spectrophotometer (product name "Spectrolino," manufactured by Gretag Macbeth), and the dye color development was evaluated according to the evaluation criteria shown below. The results are shown in Table 2. In the evaluation criteria shown below, "A" and "B" were considered desirable levels, and "C" was considered an unacceptable level. A: The OD value was 1.60 or higher. B: The OD value was between 1.50 and 1.60. The C:OD value was less than 1.50.

[0076]

Claims

1. A recording medium having an absorbent substrate and an ink-receiving layer provided on the absorbent substrate, the ink-receiving layer containing inorganic particles and a binder, The dry coating amount of the ink receiving layer is 6.0 g / m 2 More than 11.0g / m 2 is as follows: The arithmetic mean roughness Ra1 (μm) of the surface of the absorbent substrate as defined in ISO 4287:1997 satisfies the relationship of the following formula (1), the arithmetic mean roughness Ra1 and the arithmetic mean roughness Ra2 (μm) of the surface of the ink receiving layer as defined in ISO 4287:1997 satisfy the relationship of the following formula (2), A recording medium characterized in that the average length RSm1 (mm) of the roughness curve element defined in ISO 4287:1997 of the surface of the absorbent substrate and the average length RSm2 (mm) of the roughness curve element defined in ISO 4287:1997 of the surface of the ink-receiving layer satisfy the relationship of the following formula (3): Ra1≧5.0μm (1) Ra2 / Ra1≧0.87 (2) RSm2 / RSm1≦1.40 (3)

2. the inorganic particles include a first amorphous silica and a second amorphous silica; the arithmetic mean roughness Ra1 and the average secondary particle diameter D1 (μm) of the first amorphous silica satisfy the relationship of the following formula (4), 2. The recording medium according to claim 1, wherein the arithmetic mean roughness Ra1 and the average secondary particle diameter D2 (μm) of the second amorphous silica satisfy the relationship of the following formula (5). D1≦Ra1 (4) D2 ≥ Ra1 (5)

3. 3. The recording medium according to claim 1, wherein the arithmetic mean roughness Ra1 and the arithmetic mean roughness Ra2 satisfy the relationship of the following formula (6). 0.91≦Ra2 / Ra1≦1.05 (6)

4. 4. The recording medium according to claim 1, wherein the average length RSm1 of the roughness curve elements and the average length RSm2 of the roughness curve elements satisfy the relationship of the following formula (7). 0.95≦RSm2 / RSm1≦1.30 (7)

5. 5. The recording medium according to claim 1, which is for inkjet use.