JP5809591B2 - Method for producing ink jet recording material - Google Patents

Description

  The present invention relates to a method for producing an ink jet recording material in which peeling of a coating layer at a bent portion is improved when it is bent.

  The ink jet method is a printing method in which an image is recorded by ejecting ink droplets from nozzles provided in a recording head and attaching the ink to a recording material such as paper. In recent years, with the progress of ink droplet control technology and the improvement of ink and recording material performance, it has become possible to easily obtain an image comparable to a silver salt photograph. On the other hand, in the field of commercial printing, since printing can be performed directly on a medium such as paper, an ink jet recording system that is most suitable for printing a small number of copies and variable information printing (variable printing) has begun to be introduced in the field of on-demand printing.

  Conventionally, for thick greeting cards such as birthday cards, Christmas cards, wedding cards, etc., an appropriate image is printed, for example, decorated in half or folded and sent in an envelope or the like. . In the case of producing this greeting card, conventionally, a predetermined pattern is designated by a printer and printed. However, in recent years, since various images can be printed freely or easily by the ink jet recording method, greeting cards are made by the ink jet recording method.

  As a recording material used in the ink jet recording system, an ink jet recording material having an ink receiving layer on a support is known. Such ink receiving layers are roughly classified into two types: ink receiving layers mainly composed of water-soluble polymers, and porous ink receiving layers mainly composed of inorganic fine particles and a resin binder. The former ink-receiving layer absorbs ink by swelling of the water-soluble polymer, and the latter ink-receiving layer absorbs ink in voids formed by inorganic fine particles. Due to the difference in ink absorption mechanism, the former is called a swelling type (or polymer type), and the latter is called a void type (or microporous type).

  As a support for inkjet recording materials, generally, a paper support such as high-quality paper, art paper, coated paper, cast coated paper, or a resin coating in which at least one surface is coated with a resin using the paper support as a base paper Paper etc. are known. In particular, when resin-coated paper is used as the support, the resin-coated paper has a higher surface smoothness than the paper support, and can give glossiness similar to silver salt photographs to the inkjet recording material. However, unlike the paper support, the resin-coated paper itself does not have ink absorbability. For this reason, the ink receiving layer provided on the resin-coated paper is required to have extremely high ink absorbability, and the above-described void-type ink receiving layer is preferably used for such an ink receiving layer.

  Examples of the ink jet recording material having a void-type ink receiving layer include a gas phase method described in JP-B-3-56552, JP-A-10-119423, JP-A-2000-2111235, JP-A-2000-309157, and the like. An ink jet recording material provided with an ink receiving layer comprising a water-soluble binder such as silica and polyvinyl alcohol is disclosed. JP-A-9-286165, JP-A-10-181190 and the like disclose usage examples of pulverized precipitated silica, and JP-A-2001-277712 discloses examples of use of crushed gel silica. JP-A-62-174183, JP-A-2-276670, JP-A-5-32037, JP-A-6-199034 and the like disclose examples of using alumina and alumina hydrate.

  However, there are various problems in the ink jet recording material having the above-described void-type ink receiving layer. For example, when a greeting card is produced by an ink jet recording method and decorated in two, the coating layer at the folded portion is There was a problem that only the part of the film was peeled off and white, and improvement was required.

  As a method for producing an ink jet recording material having excellent bendability, for example, Japanese Patent Application Laid-Open No. 09-295454 (Patent Document 1) and Japanese Patent Application Laid-Open No. 10-6638 (Patent Document 2) include a linear pressure jig. A method of providing a region partitioned by pressurizing in a form facing at least one surface, particularly both the ink receiving layer surface and the support surface, by a pressurizing machine, or by a perforation processing machine without perforation. A method of providing a sectioned region by pressurizing at least one surface is disclosed. Japanese Patent Application Laid-Open No. 2005-161830 (Patent Document 3) discloses at least 2/3 or more of the thickness of at least an ink jet recording material formed in a V-shaped cross section from a surface provided with a synthetic resin film layer or a thermoplastic resin laminate layer. A method for forming a groove having a depth of 5 mm is disclosed, and Japanese Patent Application Laid-Open No. 11-61699 (Patent Document 4) discloses that a recording medium having an image forming layer on a substrate has at least the image forming layer linearly formed. There is disclosed a method of providing an easily bent portion that is continuously formed thinner than other portions and is easily bent. However, none of them is sufficiently satisfactory, and further improvement has been demanded.

JP 09-295454 A Japanese Patent Laid-Open No. 10-6638 JP 2005-161830 A Japanese Patent Laid-Open No. 11-61699

  An object of the present invention is to provide a method for producing an ink jet recording material in which peeling of a coating layer at a bent portion is improved when it is bent.

The above object of the present invention has been achieved by the following means.
A method for manufacturing an ink jet recording material having an ink receiving layer on at least one surface of a sheet-like support and having a linear folding designation portion on the sheet surface, wherein a plurality of pressing blades having a semicircular cross-sectional shape at the blade edge Line up and press-contact the sheet surface, and provide a ridge-shaped convex part that is a straight line at the fold-designated part that becomes a valley line when folded, or a straight and groove-shaped part at a fold-designated part that becomes a ridge line when folded A method for producing an ink jet recording material provided with a recess.

  According to the present invention, it is possible to provide a method for producing an ink jet recording material in which peeling of a coating layer at a bent portion is improved when it is bent.

  Hereinafter, the present invention will be described in detail.

  The ink jet recording material in the present invention is an ink jet recording material which is used for greeting cards, self-supporting calendars, back covers of booklets and binding files, paper craft, etc., and is scheduled to be bent after ink jet recording, and has a linear shape on the sheet surface in advance. It has a bending designation part. The method for producing an ink jet recording material of the present invention specifically relates to a method for forming this linear bending designated portion, and a plurality of press blades having a semicircular cross-sectional shape of the blade edge are stacked and pressed against the sheet surface. Then, a straight and ridge-shaped convex portion is provided in a bending designation portion that becomes a valley line when bent, or a linear and groove-like concave portion is provided in a bending designation portion that becomes a ridge line when folded. Whether to look as a convex portion or a concave portion depends on which side of the sheet is viewed, so in the present invention, a convex portion is provided when viewed from the face to be valley-folded, and a concave portion is provided when viewed from the surface to be mountain-folded .

  In the present invention, the straight and ridge-shaped convex portion or the linear and groove-shaped concave portion, which is the folding designation portion, is formed by pressing a blade-shaped pressing blade against the sheet surface. The convex part or concave part applies a pressing blade to the part that forms the concave part on the surface of the sheet, places a receiving die on the part that forms the convex part on the back side of the sheet, and applies a certain pressure between the pressing blade and the receiving mold. Can be formed. An apparatus for applying pressure is not particularly limited, and for example, a general automatic flat plate punching machine or the like can be used.

  The cross-sectional shape of the blade edge of the pressing blade used in the present invention is semicircular. The cutting edge referred to here is a blade end in contact with the processed sheet surface, and forms a semicircular shape in a cross-sectional shape connected from both side surfaces of the blade. The semicircular shape means a substantially ½ arc shape such as a perfect circle or an ellipse. The semicircular diameter is preferably 0.3 to 1.0 mm. The cutting edge may be either straight or curved, but is preferably straight from the viewpoint of increasing the efficiency of pressure welding. The blade may be a flat plate having a constant thickness or may be tapered toward the cutting edge. However, in the present invention, since a plurality of pressing blades are used side by side as described later, a flat plate having a constant thickness is used. It is preferable that it is a shape.

  In the present invention, a plurality of pressing blades such as two or three are used side by side. Two are preferred. If there is a gap between the pressing blades when arranging them, the coating layer at the bent portion may be easily peeled off, so it is preferable not to open a gap between the pressing blades.

  In the present invention, the height of the convex portion or the depth of the concave portion is preferably 0.10 to 2.0 mm. If it exceeds 2.0 mm, the printer head is likely to hit during printing with an ink jet printer, which may cause stains and poor conveyance. Moreover, if it is less than 0.10 mm, the coating layer of a bending part may become easy to peel off. The width of the convex portion or the concave portion is preferably 0.5 to 5 mm. The receiving mold is designed in the shape of a groove as the shape that forms the contour of the convex part, taking into account the width of the pressed blades and the thickness of the sheet to be processed, the height of the convex part, the depth of the concave part, etc. Just do it. In the cross-sectional shape of the receiving mold, the part forming the corner of the convex part is preferably a ¼ arc shape corresponding to the shape of the pressing blade edge, and the part forming the top part of the convex part is flat. Even if it exists, you may have a minute hook shape according to the minute V-shaped groove-shaped space | gap formed by the edge arc between the arranged pressing blades. Further, the pressure at the time of the press contact may be adjusted as appropriate so that the convex portion or the concave portion is kept in a shape until it is bent. Furthermore, the height of the convex portion or the depth of the concave portion may be set by designing the depth of the receiving die large in advance and adjusting the pressure during pressure contact.

  In the present invention, the surface on which the convex portion is provided may be the surface on the side having the ink receiving layer or the surface on the side on which the backing layer is provided. In the present invention, the surface on which the concave portion is provided may be the surface on the side having the ink receiving layer, or the surface on the side on which the backing layer is provided. As described above, according to the present invention, even if the ink receiving layer is located on either side of the convex portion or the concave portion, an excellent effect is obtained that the peeling off of the coating layer at the bent portion is improved. This is particularly effective for an ink jet recording material having an ink receiving layer. In addition, the support may be provided with a convex portion or a concave portion in advance, and then a coating layer such as an ink receiving layer may be provided. However, in order to achieve the excellent effect of the present invention, the convex portion is provided after the ink receiving layer is coated. Or it is preferable to form a recessed part.

  As the support of the ink jet recording material produced by the production method of the present invention, a paper support such as high-quality paper, art paper, coated paper, cast coated paper, or at least one of these paper supports as a base paper is used. Examples thereof include resin-coated paper whose surface is coated with resin. Among these, polyolefin resin-coated paper in which a polyolefin resin layer is coated on both sides of the base paper is preferable. The thickness of these supports is preferably 140 to 300 μm.

As the base paper constituting the polyolefin resin-coated paper, natural pulp, recycled pulp, synthetic pulp or the like is used alone or in combination. The base paper may be blended with additives such as sizing agent, paper strength enhancer, filler, antistatic agent, fluorescent whitening agent, dye and the like generally used in papermaking. Alternatively, a surface sizing agent, a surface paper strength agent, a fluorescent brightening agent, an antistatic agent, a dye, an anchor agent, or the like may be applied on the surface. The basis weight of the base paper is preferably 120 to 270 g / m ² . In addition, a paper having good surface smoothness, such as applying pressure with a calender during paper making or after paper making, is preferable.

  The polyolefin resin for coating the base paper includes olefin homopolymers such as low density polyethylene, high density polyethylene, polypropylene, polybutene, and polypentene, or copolymers composed of two or more olefins such as ethylene-propylene copolymer, and the like. Of various densities and melt viscosity indices (melt index) can be used alone or as a mixture thereof.

  In addition, in the resin of the support, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, stearic acid Fatty acid metal salts such as magnesium, antioxidants such as Irganox 1010 and Irganox 1076 commercially available from Ciba Specialty Chemicals, Inc., blue pigments such as cobalt blue, ultramarine blue, cecilian blue, and phthalocyanine blue It is preferable to add various additives such as dyes, cobalt violet, fast violet, manganese purple and other magenta pigments and dyes, fluorescent brighteners, ultraviolet absorbers and the like as appropriate.

  The polyolefin resin is produced by a so-called extrusion coating method in which a heated and melted resin is cast on a traveling base paper, and both surfaces are coated with the resin. Moreover, it is preferable to subject the base paper to activation treatment such as corona discharge treatment and flame treatment before coating the resin on the base paper. The polyolefin resin-coated paper is processed into a glossy surface, a matte surface, or the like according to its use. The thickness of the polyolefin resin layer is preferably 5 to 30 μm on one side.

An undercoat layer may be provided on the support. This undercoat layer is applied and dried in advance on the surface of the support before the ink receiving layer is applied. The undercoat layer mainly contains a water-soluble polymer or polymer latex that can form a film. Preferred are water-soluble polymers such as gelatin, polyvinyl alcohol, polyvinyl pyrrolidone and water-soluble cellulose, and particularly preferred is gelatin. Adhesion amount of the water-soluble polymer is preferably ^{10~500mg / m 2, 20~300mg / m} 2 is more preferable. Furthermore, the undercoat layer can contain other surfactants and hardeners. By providing the undercoat layer on the support, it effectively works to prevent cracking when the ink receiving layer is applied, and a uniform coated surface can be obtained.

  In the ink jet recording material produced by the production method of the present invention, an uppermost layer mainly containing colloidal silica may be provided on an ink receiving layer described later. Here, the main component means that the ratio of colloidal silica to the total solid content of the outermost layer is 50% by mass or more, and the ratio of colloidal silica is 80% by mass or more, more preferably 90% by mass or more. . Examples of colloidal silica include Snowtex XS, Snowtex OXS, Snowtex S, Snowtex ST, Snowtex OS, Snowtex 20, Snowtex 30, Snowtex 40, Snowtex O, Snowtex N, Snowtex C, Snotex AK, Snotex 50, Snotex O-40, Snotex CM, Snotex 20L, Snotex OL, Snotex XL, MP-2040, MP4540M, Snotex UP, Snotex OUP, Snotex PS-S, Snowtex PS-M (above, Nissan Chemical Industries, Ltd.), PL-1, PL-3L, PL-5, PL-7 (above, Fuso Chemical Industries, Ltd.), Cataloid S-20L, Cataloid S-20H, Cataro De S-30L, Cataloid S-30H, Cataloid SI-30, Cataloid SI-40, Cataloid SI-50, Cataloid SI-350, Cataloid SI-45P, Cataloid SI-80P, Cataloid SN, Cataloid SA, Cataloid SB, Cataloid C-125 (above, manufactured by JGC Catalysts & Chemicals Co., Ltd.).

  As the colloidal silica contained in the outermost layer, non-spherical colloidal silica is preferably used. Non-spherical colloidal silica is a general colloidal silica in which spherical or nearly spherical particles are present independently without being linked, whereas chain particles, in which small silica particles are elongated and connected, Colloidal silica having a three-dimensional network structure or a shape in which a plurality of spherical primary particles are connected.

  The colloidal silica contained in the outermost layer has an average primary particle diameter of 30 to 60 nm, a ratio of the secondary particle diameter to the average primary particle diameter of 1.4 to 3.1, and is a cationic colloidal silica. Preferably there is. The average primary particle size is the average particle size of each of 100 particles existing within a certain area from an electron micrograph of particles dispersed until the primary particle size can be determined. The ratio of the secondary particle diameter is a value obtained by calculating the ratio by obtaining the diameter of the continuous colloidal silica with respect to the average primary particle diameter determined above.

  The cationization of colloidal silica can be achieved by modifying the surface of the colloidal silica with a cationic polymer, a water-soluble polyvalent metal compound, a cationic silane coupling agent, or the like, or on the particle surface during the production of the colloidal silica. Can be cationized by introducing. For surface decoration, cationization with a cationic silane coupling agent and a water-soluble polyvalent metal compound is preferred, and a water-soluble polyvalent metal compound is more preferred. The measured value of the zeta potential at that time is preferably +5 to +70 mV.

The solid coating amount of the colloidal silica particles contained in the outermost layer which is laminated on the ink-receiving layer is preferably from 0.05 to 0.5 g / ^{m 2,} more in the range of 0.08~0.2g / ^{m 2} preferable.

  The outermost layer can also contain a resin binder. Such a resin binder has the same meaning as a resin binder used in an ink receiving layer described later.

  The ink jet recording material produced by the production method of the present invention has at least one ink receiving layer on a support, and the ink receiving layer is preferably a void-type ink receiving layer, and has an average secondary particle size. Is more preferably an ink receiving layer mainly containing inorganic fine particles of 500 nm or less. Here, “mainly contained” means that the inorganic fine particles are contained in an amount of 50% by mass or more, more preferably 60% by mass or more, based on the solid coating amount of the ink receiving layer.

  Inorganic fine particles having an average secondary particle size of 500 nm or less contained in the ink receiving layer include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, titanium dioxide, zinc oxide, zinc hydroxide, calcium silicate, magnesium silicate, Synthetic silica, alumina, alumina hydrate, magnesium hydroxide and the like can be mentioned, and a mixture of two or more of these can be mentioned. Among these, synthetic silica, alumina, or alumina hydrate is preferable, and these inorganic fine particles are advantageous in terms of cost because a high printing density and a clear image can be obtained. More preferable inorganic fine particles in the present invention are amorphous synthetic silica, alumina, or alumina hydrate.

  Amorphous synthetic silica can be roughly classified into wet method silica and gas phase method silica depending on the production method. Vapor phase silica is also called a dry method as opposed to a wet method, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or in silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd.

  Wet method silica is further classified into precipitation method silica, gel method silica, and sol method silica according to the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, and are then commercialized through filtration, water washing, drying, pulverization and classification. The secondary particles of silica produced by this method become loosely agglomerated particles, and particles that are relatively easy to grind are obtained. Precipitated silica is commercially available, for example, as a nip seal from Tosoh Silica Co., Ltd., as a Toku Seal from Tokuyama Co., Ltd., and as a fine seal. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During the ripening, the fine particles dissolve and reprecipitate so as to bind other primary particles, so that the distinct primary particles disappear and form relatively hard aggregated particles having an internal void structure. For example, commercially available as Toyo Silica Co., Ltd. as nip gel, from Mizusawa Chemical Industry Co., Ltd. as Mizukasil, from Grace Japan Co., Ltd. as syloid and silo jet.

The vapor phase silica that can be used in the present invention will be described. The average primary particle diameter of the vapor phase silica used in the present invention is preferably 30 nm or less, and preferably 15 nm or less in order to obtain higher gloss. More preferably, an average primary particle diameter of 3 to 15 nm and a specific surface area by BET method of 200 m ² / g or more (preferably 250 to 500 m ² / g) are used. Note that the average primary particle diameter here is an average particle diameter obtained by observing the diameter of a circle equal to the projected area of each of the 100 primary particles existing within a certain area by observation with an electron microscope. The BET method referred to in the present invention is one of the powder surface area measurement methods by the vapor phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from the adsorption isotherm. . Usually, nitrogen gas is often used as the adsorbed gas, and the most frequently used method is to measure the amount of adsorption from the change in pressure or volume of the gas to be adsorbed. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller equation, called the BET equation, which is widely used for determining the surface area. The adsorption amount is obtained based on the BET equation, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface.

  The ink receiving layer may be prepared by dispersing gas phase method silica in the presence of a cationic polymer and having an average secondary particle diameter of the gas phase method silica of 500 nm or less, preferably 10 to 300 nm. In order to make the average secondary particle diameter of the gas phase method silica not more than 500 nm, the gas phase method silica and the dispersion medium are premixed by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., and then a ball mill, It is preferable to perform dispersion using a media mill such as a bead mill or a sand grinder, a pressure disperser such as a high pressure homogenizer, an ultra high pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, or the like. The average secondary particle diameter as used in the present invention can be determined by photographing the ink-receiving layer of the obtained recording material with an electron microscope. For simplicity, a laser scattering type particle size distribution analyzer is used for the dispersion. The number median diameter can be measured using (for example, LA920 manufactured by Horiba, Ltd.).

  Examples of the cationic polymer used for the dispersion of the vapor phase silica include polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP JP 59-33177, JP 59-1555088, JP 60-11389, JP 60-49990, JP 60-83882, JP 60-109894. JP, 62-198493, JP 63-49478, JP 63-115780, JP 63-280681, JP 1-40371, JP 6-6 No. 234268, JP-A-7-125411, JP-A-10-19376, and the like. Polymers having Moniumu base is preferably used. In particular, diallylamine derivatives are preferably used as the cationic polymer. In terms of dispersibility and dispersion viscosity, the molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000. The amount of the cationic polymer used is preferably in the range of 1 to 10% by mass with respect to the vapor phase silica.

  Next, the wet method silica will be described. The wet process silica used in the present invention is precipitated silica or gel process silica. The silica powder before pulverization preferably has an average primary particle size of 50 nm or less, more preferably 3 to 40 nm, and an average aggregate particle size (secondary particle size) of 5 to 50 μm. In the present invention, these wet process silica is used, for example, a media mill such as a ball mill, a bead mill, a sand grinder, a pressure disperser such as a high pressure homogenizer, an ultrahigh pressure homogenizer, an ultrasonic disperser, and a thin film swirl disperser. By doing so, it is possible to use a material pulverized to an average secondary particle size of 500 nm or less, preferably 10 to 300 nm in an aqueous medium. The pulverization is preferably performed in the presence of a cationic compound.

  Since the wet process silica produced by a normal method has an average aggregate particle diameter of 1 μm or more, it is used after being pulverized. In order to make the average secondary particle diameter of the wet method silica 500 nm or less, a wet dispersion method in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. At this time, the increase in the initial viscosity of the dispersion is suppressed, high concentration dispersion is possible, and the pulverization / dispersion efficiency is increased so that the particles can be further pulverized. Therefore, the oil absorption is 210 ml / 100 g or less, the average aggregated particle diameter It is preferable to use precipitated silica of 5 μm or more. By using a high-concentration dispersion, the productivity of the recording material is also improved. The oil absorption is measured based on the description of JIS K-5101.

  As a method for pulverizing the wet method silica used in the present invention, the same method as the dispersion of the vapor phase method silica can be used. Moreover, the thing similar to what is used in order to cationize the said gaseous-phase method silica as a dispersing agent can be used.

  As the wet process silica used in the ink receiving layer of the present invention, precipitated silica is preferable. As described above, precipitated silica is suitable for pulverization because its secondary particles are loosely agglomerated particles.

  As the inorganic fine particles having an average secondary particle diameter of 500 nm or less contained in the ink receiving layer, alumina or alumina hydrate is also preferably used. Alumina or alumina hydrate is aluminum oxide or a hydrated product thereof, which may be crystalline or amorphous and has an amorphous shape, a spherical shape, a plate shape, or the like. Either of them may be used or may be used in combination.

  As the alumina oxide that can be used in the present invention, γ-alumina, which is a γ-type crystal of aluminum oxide, is preferable, and δ group crystal is particularly preferable. Although γ-alumina can reduce the primary particles to about 10 nm, normally, secondary particle crystals of several thousand to several tens of thousands nm are averaged by ultrasonic waves, a high-pressure homogenizer, a counter collision type jet crusher, or the like. Those having a secondary particle size of 500 nm or less, preferably about 50 to 300 nm can be used.

The alumina hydrate that can be used in the present invention is represented by a constitutional formula of Al ₂ O ₃ .nH ₂ O (n = 1 to 3). The hydrated aluminum oxide can be obtained by a known production method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate, and the like. The average secondary particle diameter of the alumina hydrate used in the present invention is 500 nm or less, preferably 10 to 300 nm.

  As the alumina and alumina hydrate used in the present invention, those having an average secondary particle size of 500 nm or less dispersed by a known dispersant such as acetic acid, lactic acid, formic acid, methanesulfonic acid, hydrochloric acid, nitric acid are preferably used. .

  In the ink receiving layer, a hydrophilic resin binder is used in order to maintain the characteristics as a film and to obtain a higher transparency and high ink permeability. As the resin binder, polyvinyl alcohol, polyethylene glycol, starch, dextrin, carboxymethyl cellulose, polyvinyl pyrrolidone, polyacrylic acid ester and derivatives thereof are used, and particularly preferable resin binder is completely or partially saponified polyvinyl alcohol. is there. Particularly preferred among polyvinyl alcohols are those having a saponification degree of 80% or more, or those completely saponified. Polyvinyl alcohol having an average degree of polymerization of 500 to 5000 is preferable.

  In the ink receiving layer, the mixing ratio of the resin binder and the inorganic fine particles has a preferable range, and a preferable range is appropriately selected depending on the kind of the inorganic fine particles. For synthetic silica, it is preferable to use 10 to 30% by mass of a resin binder, particularly preferably 12 to 25% by mass. For alumina or alumina hydrate, 5 to 25% by mass of a resin binder is preferably used, and 7 to 15% by mass is particularly preferable.

The ink receiving layer may be a single layer or two or more layers. The solid content coating amount of the ink receiving layer varies depending on the inorganic fine particles to be applied. The solid coating amount in the case of fumed silica single layer is preferably 5 to 30 g / ^{m 2,} the range of 15 to 30 g / ^{m 2} is more preferable. 10-40 g / m < ² > is preferable and, as for the solid content coating amount in the case of an alumina or an alumina hydrate single layer, 15-35 g / m < ² > is more preferable. 10-40 g / m < ² > is preferable and, as for the total solid content at the time of laminating | stacking a vapor-phase-process silica, an alumina, and an alumina hydrate, 15-35 g / m < ² > is more preferable.

  The ink receiving layer of the present invention preferably contains a hardener together with a resin binder. Specific examples of the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea), 2-hydroxy-4,6-dichloro-1 , 3,5-triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, a reactive olefin as described in US Pat. No. 3,635,718 N-methylol compounds as described in US Pat. No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. No. 3,017,280 Aziridine compounds as described in U.S. Pat. No. 2,983,611, U.S. Pat. No. 3,100,704 Carbodiimide compounds such as, epoxy compounds as described in US Pat. No. 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, zirconium sulfate, boric acid and borates There are inorganic hardeners and the like, and these can be used alone or in combination of two or more. Among these, boric acid or borate is particularly preferable. The addition amount of the hardener is preferably 0.1 to 40% by mass, more preferably 0.5 to 30% by mass with respect to the resin binder constituting the ink receiving layer.

  In the present invention, the ink receiving layer and the uppermost layer include various oil droplets, coloring dyes, coloring pigments, ultraviolet absorbers, antioxidants, pigment dispersants, antifoaming agents, leveling agents, which improve the brittleness of the film. Various known additives such as preservatives, optical brighteners, viscosity stabilizers, pH adjusters and the like can also be added.

  In the present invention, the coating method when providing the ink receiving layer and the uppermost layer is not particularly limited, but a coating device such as a slide bead coater, curtain coater, extrusion coater, air knife coater, rod coater, blade coater, gravure coater, etc. Can be used alone or in combination. When the ink receiving layer and the uppermost layer are applied simultaneously, a slide bead coater or curtain coater application device can be used. When the uppermost layer is sequentially applied after the ink-receiving layer is applied, the above-described application apparatuses can be used in appropriate combination. In the present invention, simultaneous application means that the respective layers are applied almost simultaneously. Sequential application is to apply the uppermost coating liquid after the gap of the ink-receiving layer is formed after the decreasing rate drying step.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In Examples and Comparative Examples, “parts” and “%” indicate solid parts or mass parts and mass% of solid components unless otherwise specified.

<Example 1>
(Production of support)
A pulp slurry was prepared by beating a 1: 1 mixture of hardwood kraft pulp (LBKP) and softwood sulfite pulp (NBSP) to 300 ml with Canadian Standard Freeness. As a sizing agent, alkylketene dimer is 0.5% to pulp, polyacrylamide is 1.0% to pulp, and cationized starch is 2.0% to pulp. Polyamide epichlorohydrin resin is 0 to pulp. 0.5% added and diluted with water to give a 0.2% slurry. This slurry was made with a long paper machine to a basis weight of 240 g / m ² , dried and conditioned to obtain a base paper for the support. A polyethylene resin composition in which 10% anatase-type titanium is uniformly dispersed with respect to a low density polyethylene resin having a density of 0.918 g / cm ³ is melted at 320 ° C. on both sides of the base paper made at a temperature of 200 m / min. The coating was extrusion coated to a thickness of 17 μm and extrusion coated using a cooling roll with a finely roughened surface.

An ink receiving layer coating solution having the following composition was applied to each of both surfaces of the support with a slide bead coating device so that the solid content on each surface was 25 g / m ² , cooled at 5 ° C. for 30 seconds, and then 40 ° C. 10 Dry to the end of drying with% RH. Thereafter, the top layer coating solution having the following composition was sequentially applied to each surface with a gravure coating apparatus so that the solid content of the colloidal silica was 0.1 g / m ² and dried at 50 ° C.

[Gas phase silica dispersion]
After adding 3 parts of dimethyldiallyl aluminum chloride homopolymer (molecular weight: 9000) and 100 parts of vapor phase method silica (average primary particle size 7 nm, specific surface area 300 m ² / g) to water to prepare a preliminary dispersion, using a high-pressure homogenizer The gas phase process silica dispersion liquid of 20 mass% of solid content concentration was processed and produced. In addition, the average secondary particle diameter of the vapor phase method silica measured by a laser diffraction / scattering particle size distribution analyzer was 80 nm.

[Ink-receiving layer coating solution]
Gas phase method silica dispersion 103 parts boric acid 5 parts polyvinyl alcohol 23 parts (saponification degree 88%, average polymerization degree 3500)
It adjusted with water so that solid content concentration might be 12 mass%.

[Top layer coating solution]
Add 100 parts of Quartron PL-3L (colloidal silica manufactured by Fuso Chemical Industry Co., Ltd.) to the water to prepare a 5% by mass solids concentration solution, and then stir and stir 10 parts of tachyvine # 1500 (multiple) over about 10 minutes. A polyaluminum chloride aqueous solution manufactured by Ki Chemical Co., Ltd .; solid content concentration 23.5% by mass) was added to obtain cationic colloidal silica. After completion of the addition, the mixture was stirred at a temperature of 80 ° C. for 1 hour, cooled to room temperature, and adjusted with water so that the solid content concentration became 0.6% by mass. As a result of measuring the zeta potential of the produced top layer coating solution 1 with a zeta potential measuring device (DELSA 440SX manufactured by Beckman Coulter, Inc.), it was +45 mV. The average primary particle size of the cationic colloidal silica as observed by electron microscope was 35 nm, and the ratio of the average secondary particle size to the average primary particle size was 1.5.

  The inkjet recording material obtained as described above was cut into a 178 mm × 254 mm sheet. Install two opposed 0.45mm thick pressing blades with a semi-circular cutting edge with a straight section and a diameter of 0.45mm on the automatic flat plate punching machine, without any gaps. Installed. The receiving mold was designed in a groove shape according to the width of the arranged pressing blades of about 0.9 mm, the thickness of the sheet to be processed, and the height of the convex part to be formed of 0.2 mm. In the cross-sectional shape of the receiving mold, the portion forming the corner of the convex portion was a quarter arc shape corresponding to the shape of the pressing blade edge, and the portion forming the top of the convex portion was flat. Using this automatic flat plate punching machine, a width of about 1.5 mm and a height of about 0.2 mm across a line connecting the center of one long side of the ink jet recording material and the center of the other long side. A hook-shaped convex portion (a concave portion as viewed from the opposite surface) was provided.

<Comparative Example 1>
Change the pressing blade to a single 0.45 mm thick pressing blade with a semicircular cutting edge with a straight section and a diameter of 0.45 mm, and use a 1/2 arc shaped receiving die designed accordingly In the same manner as in Example 1 except that the ridge-shaped convex portion (groove-shaped concave portion viewed from the opposite surface) having a width of about 1 mm and a height of about 0.2 mm was provided.

<Comparative Example 2>
Change the press blades to two 0.45 mm thick press blades that are straight and have a cross-sectional width of 0.45 mm and square corners with a right angle (installed side by side without any gaps). According to the same manner as in Example 1 except that a receiving mold having a right corner is designed according to the design, a ridge-shaped convex portion having a width of about 1.5 mm and a height of about 0.2 mm (a groove-shaped concave portion as viewed from the opposite surface). ).

<Example 2>
Changed the press blade into two straight 0.75 mm thick press blades with a semicircular cutting edge with a cross-sectional diameter of 0.75 mm (mounted side by side with no gaps), and designed corners accordingly A ridge-shaped convex portion (groove-shaped concave portion as viewed from the opposite side) having a width of about 2.1 mm and a height of about 0.35 mm, in the same manner as in Example 1, except that a receiving part having a quarter arc shape is used. Was provided.

<Example 3>
Except that the receiving mold is designed so that the height of the convex portion is 0.12 mm, the ridge-shaped convex portion having a width of about 1.3 mm and a height of about 0.12 mm (viewed from the opposite surface) is the same as in Example 1. Groove-shaped recess).

<Example 4>
Change the press blades to three 0.45 mm thick press blades with a semicircular cutting edge with a diameter of 0.45 mm and a cross-sectional shape (mounted side by side with no gaps), and change the groove width accordingly. Except for using the modified receiving mold, a ridge-shaped convex portion (groove-shaped concave portion as viewed from the opposite surface) having a width of about 2 mm and a height of about 0.2 mm was provided in the same manner as in Example 1.

  As described above, the following evaluation was performed on the ink jet recording material provided with a convex portion (a groove-like concave portion when viewed from the opposite surface) on one surface. The results are shown in Table 1.

<Coating layer peeling>
After printing photographic images on both sides with an inkjet printer, fold the recording material until the valley-side surface is in full contact with the trough-shaped convex part as the trough line (with the groove-shaped concave part as the ridgeline), and the coating layer peels off at the folded part (crest side, Valley side) was evaluated.
A: The coating layer does not peel off on both the mountain side and the valley side.
○: There is a slight peeling of the coating layer on the mountain side.
(Triangle | delta): There exists white line-like coating layer peeling in the mountain side.
X: There is peeling of the coating layer on both the mountain side and the valley side.

  As is apparent from the above results, it can be seen that the present invention can provide an ink jet recording material with improved peeling of the coating layer when bent.

Claims (1)

  A method for producing an ink jet recording material having an ink receiving layer on at least one surface of a sheet-like support and having a linear folding designation portion on the sheet surface, wherein a plurality of pressing blades having a semicircular cross-sectional shape at the blade edge are provided. Line up and press-contact the sheet surface, and provide a ridge-shaped convex part that is a straight line at the fold-designated part that becomes a valley line when folded, or a straight and groove-shaped part at a fold-designated part that becomes a ridge line when folded A method for producing an ink jet recording material provided with a recess.