JP4496089B2 - Method for producing ink jet recording material - Google Patents

Description

  The present invention relates to a method for manufacturing an ink jet recording material, and more particularly to a method for manufacturing an ink jet recording material that enables stable continuous application for a long time.

  As a recording material used in the ink jet recording method, a recording material in which an ink receiving layer is provided on a support such as paper or a plastic resin film is known. The ink receiving layer is roughly classified into two types. One type is an ink receiving layer mainly composed of a water-soluble polymer, and the other type is an ink receiving layer mainly composed of inorganic fine particles.

  The former type of ink receiving layer absorbs ink by swelling the water-soluble polymer. The latter type of ink receiving layer absorbs ink in voids formed by inorganic fine particles. Due to the difference in ink absorption mechanism, the former type is called a swelling type (or polymer type), and the latter type is called a void type.

  The void type is excellent in image quality, drying property after printing, and the like, and a photo-like ink jet recording material in which a void type ink-receiving layer is provided on a water-resistant support such as a polyolefin resin-coated paper is widely used.

  The void-type ink jet recording material described above is manufactured by applying a coating liquid in which a dispersion slurry of inorganic fine particles and a hydrophilic binder are mixed on a support and drying. Examples of the application method used here include a slide bead method using a slide hopper, a slide curtain method, a slot die method, a rod bar method, a gravure roll method, an air knife method, and a blade method. Among these application methods, from the viewpoint of production efficiency, a slide bead method and a slide curtain method using a slide hopper that can apply a plurality of ink receiving layers simultaneously and can apply at high speed are preferable.

  When the coating liquid of the ink receiving layer mainly containing inorganic fine particles is applied by a coating method using a slide hopper, particularly when the coating liquid is applied as the uppermost layer, both end portions in the coating width direction on the slide surface There was a problem that the (part flowing down in contact with the coating width regulating plate) was partially fixed and the coating width was reduced, and stable continuous coating for a long time was not possible.

As a method for solving the above problem, Japanese Patent Application Laid-Open No. 2002-274020 (Patent Document 1) discloses a method of supplying water to both ends. Japanese Patent Laying-Open No. 2004-255352 (Patent Document 2) discloses a method of setting the relative humidity of the slide surface atmosphere to 70 to 90%. However, these methods are still insufficient.
JP 2002-274020 A JP 2004-255352 A

  Accordingly, an object of the present invention is to provide a method for producing an ink jet recording material capable of stably and continuously applying a void type ink receiving layer over a long time on a support.

The above object of the present invention has been basically achieved by the following invention.
(1) on a support, the ink receiving layer containing inorganic fine particles mainly is a method for producing an ink jet recording material for coating using a slide hopper type coating apparatus so that the top layer, the top layer coating The concentration of inorganic fine particles in the working liquid is 5% by mass or more, the moisture application amount is 30 g / m ² or less, and the uppermost coating liquid starts flowing down on the slide surface of the slide hopper type coating apparatus. A method for producing an ink jet recording material, characterized in that an aqueous solution containing polyvinyl alcohol or dipropylene glycol is supplied at a flow rate of 10 ml / min or less per side immediately after or upstream of both ends in the width direction.

  According to the present invention, it is possible to stably and continuously apply a void type ink receiving layer mainly containing inorganic fine particles over a long period of time.

  The production method of the present invention will be described in detail below. The production method of the present invention is applied on a support using a slide hopper type coating apparatus so that the ink receiving layer mainly containing inorganic fine particles is the uppermost layer. In the present invention, a coating method using a slide hopper type coating device is a slide bead coating method or a slide curtain coating method.

  A slide hopper type coating apparatus usually has a plurality of units each composed of a cavity and a slit inside the apparatus, and each unit slide surface for allowing the coating liquid pushed out from the slit to flow uniformly over the coating width direction. Have The coating liquid that is continuously supplied to the slide hopper type coating device with a pump or the like is once spread in the width direction in the cavity and becomes a liquid film having a uniform thickness in the width direction when passing through the slit. And pushed down on the slide surface.

  The slide bead coating method using such a slide hopper coating apparatus is disclosed in JP-A-5-96223, JP-A-11-290775, JP-A-2000-33314, JP-A-2002-274020, and JP-A-2004. -255352 and the like, and the coating liquid flows down the slide surface and is applied while forming a bead between the tip (lip tip) of the slide surface and the support.

  The slide curtain coating method is described in JP-A-10-277458, JP-A-200-176344, JP-A-2001-46938, JP-A-2002-274020, and the like. The film is a system in which a curtain film is formed between the tip of the slide surface and the support, and the curtain film is dropped onto the support and applied.

  In the slide hopper coating apparatus, a coating width regulating plate is usually provided on the slide surface, and the coating width is adjusted by the regulating plate. Accordingly, both ends of the coating liquid flowing down the slide surface flow down while contacting the coating width regulating plate. At the liquid contact boundary surface between the regulating plate and the coating liquid, the flow speed decreases due to the viscous resistance of the coating liquid, and the amount of water evaporation is reduced by the continuous application over a long period of time. In many cases, an undesired phenomenon that the solid content concentration was increased and partially dried and fixed occurred. Such a problem becomes prominent when the uppermost layer coating liquid mainly contains inorganic fine particles, and is more likely to occur when the amount of moisture applied to the uppermost layer is small. A high partial concentration promoted the above problem.

  The above-mentioned problem cannot be solved sufficiently by the above-described conventional technology, for example, a method of supplying water to both ends or a method of increasing the relative humidity of the slide surface atmosphere. Therefore, the present invention uses a liquid (auxiliary liquid) supplied to both ends as an aqueous solution containing a water-soluble polymer or a water-soluble polyhydric alcohol, and the supply amount is 10 ml / min or less per side. It has been found that the above-mentioned problems can be solved without problems such as failure and increased drying load.

  In the present invention, the supply position of the auxiliary liquid is immediately after the uppermost coating liquid starts flowing on the slide surface or at both ends on the upstream side. The supply position of the auxiliary liquid will be described in detail with reference to the drawings.

  FIG. 1 is a plan view (top view) of an embodiment of a slide hopper coating apparatus used in a slide bead coating method. The slide hopper coating apparatus 11 illustrated in FIG. 1 is an apparatus capable of simultaneous three-layer coating, and includes a front bar 1, a second bar 2, a third bar 3, and a back bar 4. Each bar has slide surfaces 1a, 2a, 3a, and 4a, and slits 1b, 2b, and 3b. Application width regulating plates 5 are provided at both ends on the slide surface.

  The coating liquid supplied to the coating device 11 is pushed out from the slits (1b, 2b, 3b) and flows down the slide surfaces (1a, 2a, 3a). At this time, both ends of the liquid film of the coating liquid flow down while contacting the coating width regulating plate 5.

  When the coating liquid is applied, the front end portion (lip front end portion) 6 of the front bar 1 is a coating liquid that has flowed down the slide surface in a gap (100 to 500 μm) with the traveling support (not shown). Has the role of forming a bead.

  In the present invention, the supply position of the auxiliary liquid is at both ends of the uppermost layer, and is immediately after the uppermost coating liquid starts to flow on the slide surface or on the upstream side thereof. Here, both end portions are in the vicinity of the coating width regulating plate 5 and immediately after the uppermost coating liquid starts flowing on the slide surface is a position close to the slit (within about 1 cm from the slit). .

  Specifically, for example, when two layers of the ink receiving layer are applied simultaneously, the uppermost coating liquid is pushed out from the slit 2b and flows down the slide surface 2a. In this case, the auxiliary liquid supply position is 7 (position immediately after the topmost coating liquid starts flowing on the slide surface) indicated by ▲, or upstream (the coating liquid is on the slide surface). In the opposite direction to flowing down). Preferably, a position upstream from the slit (in this case, slit 2b) through which the uppermost coating liquid is extruded, more preferably a position close to the slit upstream (within about 1 cm from the slit), This is the position of symbol 8 indicated by ●.

  In the present invention, the supply amount of the auxiliary liquid is 10 ml / min or less per side, preferably 0.3 to 7 ml / min, and more preferably 0.5 to 5 ml / min.

  As a means for supplying the auxiliary liquid, a means that can supply substantially continuously even at an extremely low supply rate of 10 ml or less per minute is preferable, and a nozzle having a small tip diameter is preferably used. It is preferable to supply from above the slide surface using such a nozzle and a low speed pump.

Next, the auxiliary liquid used in the present invention will be described in detail. The auxiliary liquid of the present invention contains polyvinyl alcohol or dipropylene glycol . The aqueous solution may contain, as a solvent other than water, 10% by mass or less of a low boiling alcohol (alcohol having a boiling point of 100 ° C. or lower; ethyl alcohol, etc.). As for the viscosity (25 degreeC viscosity) of this aqueous solution, 15 mPa * s or less is preferable.

The concentration of polyvinyl alcohol in the auxiliary liquid is preferably in the range of 0.2 to 5 wt%, preferably particularly from 0.5 to 3% by weight.

The concentration of dipropylene glycol in the auxiliary liquid is preferably in the range of 0.2 to 8 wt%, preferably particularly from 0.5 to 5% by weight.

  Next, the configuration of the ink receiving layer will be described in detail. The ink receiving layer of the present invention mainly contains inorganic fine particles. Here, “mainly contained” means that the inorganic fine particles are contained in an amount of 60% by mass or more with respect to the total solid content of the ink receiving layer, and it is particularly preferably contained in the range of 65 to 95% by mass. Examples of the inorganic fine particles used in the ink receiving layer of the present invention include various known fine particles such as amorphous synthetic silica, alumina, alumina hydrate, calcium carbonate, magnesium carbonate, and titanium dioxide. Amorphous synthetic silica, alumina, or alumina hydrate is preferred from the viewpoint of properties.

  Amorphous synthetic silica can be roughly classified into wet method silica, gas phase method silica, and others depending on the production method. 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 the steps of filtration, washing, drying, pulverization and classification. Precipitated silica is commercially available, for example, from Tosoh Silica Co., Ltd. as a nip seal and from Tokuyama Co., Ltd. as a Toxeal. Gel silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During aging, the microparticles dissolve and reprecipitate so as to bind the other primary particles, so that the distinct primary particles disappear and form relatively hard aggregated particles having an internal void structure. For example, it is commercially available as nip gel from Tosoh Silica Co., Ltd., and as syloid and silo jet from Grace Japan Co., Ltd. The sol method silica is also called colloidal silica, and is obtained by heating and aging a silica sol obtained through metathesis of sodium silicate acid or through an ion exchange resin layer. For example, it is commercially available as Snowtex from Nissan Chemical Industries, Ltd. Yes.

  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 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.

The vapor phase method silica used in the present invention preferably has an average primary particle size of 30 nm or less, more preferably 15 nm or less, and a specific surface area by the BET method of 200 m ² / g or more (preferably 250 to 500 m ² / g). . The average primary particle diameter as used in the present invention is an average particle diameter obtained by measuring 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, as the adsorbed gas, a large amount of nitrogen gas is used, and the most frequently used method is to measure the amount of adsorption from the pressure or volume change of the gas to be adsorbed. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller formula, called the BET formula, 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 gas phase method silica is preferably dispersed in the presence of a cationic compound. At this time, the gas phase method silica is preferably dispersed so that the average secondary particle diameter is 500 nm or less, preferably 30 to 300 nm. As such a dispersion method, pre-mixing of the gas phase method silica and the dispersion medium by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., followed by a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, It is preferable to perform dispersion using a pressure disperser such as a 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 refers to an average value of the particle diameters of the dispersed aggregated particles observed by observing the ink receiving layer of the obtained recording material with an electron microscope. It is.

  In the present invention, wet-process silica may be used as it is as elementary particles having an average secondary particle diameter of 1 μm or more, or the elementary particles may be used after being finely pulverized to 500 nm or less. When the wet process silica is finely pulverized, it is preferably carried out in the presence of a cationic compound.

  As a method of finely pulverizing the wet method silica, a wet dispersion method of mechanically pulverizing silica dispersed in an aqueous medium 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 recording paper is also improved. The oil absorption is measured based on the description of JIS K-5101.

  In the present invention, a specific method of pulverizing to an average secondary particle size of 500 nm or less will be described. First, silica particles and a cationic compound are mixed in a dispersion medium mainly composed of water, and at least one dispersion device such as a sawtooth blade type dispersion machine, a propeller blade type dispersion machine, or a rotor stator type dispersion machine is used. Used to obtain a preliminary dispersion. If necessary, an appropriate low boiling point solvent or the like may be added to the aqueous dispersion medium. The higher the solid content concentration of the silica pre-dispersion liquid, the more preferable, but when the concentration is too high, it becomes impossible to disperse, so the preferable range is 15 to 40% by mass, and more preferably 20 to 35% by mass. Next, the silica particles are pulverized by applying the silica pre-dispersion to mechanical means having a stronger shearing force to obtain a wet process silica fine particle dispersion having an average secondary particle size of 500 nm or less. As a mechanical means, a known method can be adopted, for example, a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, a pressure disperser such as an ultra high pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, etc. Can be used.

  As the cationic compound used for the dispersion of the gas phase method silica and the wet method silica, a cationic polymer can be preferably used. As the cationic polymer, polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-155088, Sho 60-11389, Sho 60-49990, Sho 60-83882, Sho 60-109894, Sho 62-198493, Sho 63-49478, Sho 63-115780, Shosho 63-280681, No. 1-40371, No. 6-234268, No. 7-125411, No. 10-193976, etc. The polymer having 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.

  As the alumina that can be used in the present invention, γ-alumina, which is a γ-type crystal of aluminum oxide, is preferable, and among them, a δ group crystal is preferable. γ-alumina can make primary particles as small as about 10 nm. Usually, secondary particles of thousands to tens of thousands of nanometers are averaged by ultrasonic, high-pressure homogenizer, counter collision type jet crusher, etc. What grind | pulverized the particle diameter to 500 nm or less, Preferably about 20-300 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 case where n is 1 represents an alumina hydrate having a boehmite structure, and the case where n is greater than 1 and less than 3 represents an alumina hydrate having a pseudo boehmite structure. It can be obtained by a known production method such as hydrolysis of an aluminum alkoxide such as aluminum isopropoxide, neutralization of an aluminum salt with an alkali, or hydrolysis of an aluminate. The average secondary particle diameter of the alumina hydrate used in the present invention is 500 nm or less, preferably 20 to 300 nm.

  The above-mentioned alumina and alumina hydrate used in the present invention are used in the form of a dispersion dispersed by a known dispersant such as acetic acid, lactic acid, formic acid, nitric acid and the like.

  The ink receiving layer preferably contains a resin binder for fixing the inorganic fine particles. As such a resin binder, a hydrophilic binder that has high transparency and higher ink permeability is preferably used. In using the hydrophilic binder, it is important that the hydrophilic binder does not swell at the initial permeation of the ink and block the gap. From this viewpoint, a hydrophilic binder having a low swelling property near room temperature is preferably used. .

  Examples of such hydrophilic binders include polyvinyl alcohol, polyethylene glycol, starch, dextrin, carboxymethyl cellulose, and derivatives thereof, and particularly preferred hydrophilic binders include completely or partially saponified polyvinyl alcohol, or cations, silanols, and acetoacetyl. Modified polyvinyl alcohol. Particularly preferred among polyvinyl alcohols are those having a degree of saponification of 80% or more or those that have been completely saponified, and the average degree of polymerization is preferably from 500 to 5,000.

  It is preferable to contain the resin binder mentioned above in the range of 5-55 mass% with respect to inorganic fine particles, and it is preferable to contain especially in the range of 10-30 mass%.

  The ink receiving layer of the present invention preferably contains a resin binder hardener. Such hardeners 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 compound having a reactive olefin as described in US Pat. No. 3,635,718, US Pat. N-methylol compounds as described in US Pat. No. 732,316, isocyanates as described in US Pat. No. 3,103,437, aziridine compounds as described in US Pat. Nos. 3,017,280 and 2,983,611 Carbodiimide compounds as described in US Pat. No. 3,100,704, US Pat. There are epoxy compounds as described in No. 091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, inorganic hardeners such as zirconium sulfate, boric acid and borates. Species or a combination of two or more can be used. 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 hydrophilic binder constituting the ink absorbing layer.

  The ink receiving layer of the present invention further includes the above-mentioned cationic polymer, water-soluble polyvalent metal compound, for example, aluminum compound such as basic polyaluminum hydroxide, zirconium salt such as zirconium acetate, zirconium sulfate, zirconium oxychloride, etc. It is preferable to contain. The ink receiving layer may further contain a surfactant, preservative, colorant and the like.

  The production method of the present invention is applied when the ink receiving layer mainly containing inorganic fine particles is applied so as to be the uppermost layer. As described above, the uppermost ink receiving layer mainly contains inorganic fine particles. When only one ink receiving layer is applied, that ink receiving layer is the uppermost layer. Therefore, the layer structure applied to the manufacturing method of the present invention may be composed of only one layer, or may be composed of two or more layers. In the case of two or more layers, the ink receiving layer other than the uppermost layer is also preferably an ink receiving layer mainly containing inorganic fine particles as described above, and these ink receiving layers are applied simultaneously in multiple layers.

  In the present invention, the uppermost ink-receiving layer coating solution is a water-soluble coating solution containing water as a main component. By increasing the concentration of the inorganic fine particles in the coating solution, the moisture application amount of the coating solution can be reduced, and the drying efficiency is improved. However, when the concentration of the inorganic fine particles is increased to reduce the coating amount, the above-described problem of the present invention is more likely to occur. Therefore, the present invention exhibits a great effect when the coating amount is decreased by increasing the concentration of the uppermost inorganic fine particles.

  In addition, on the main ink receiving layer (layer that absorbs most of the printed ink), the uppermost layer for enhancing gloss, or conversely, the uppermost layer for imparting writing properties such as postcard use, The effect of the present invention can be enjoyed even when it is provided as a thin layer.

Therefore, the production method of the present invention is suitable for application under the condition that the concentration of the inorganic fine particles in the uppermost layer coating liquid is 5% by mass or more and the moisture application amount is 30 g / m ² or less, and is highly effective. can get.

  The support used in the present invention is water resistant support for polyethylene, polypropylene, polyvinyl chloride, diacetate resin, triacetate resin, cellophane, acrylic resin, polyethylene terephthalate, polyethylene naphthalate and other plastic resin films, polyolefin resin coated paper, etc. And water-absorbing supports such as body, fine paper, art paper, coated paper and cast coated paper. Among these supports, water-resistant supports such as plastic resin films and polyolefin resin-coated paper are particularly preferably used. Further, among the water-resistant supports, polyolefin resin-coated paper is preferable. The thickness of these supports is preferably about 50 to 250 μm.

  Various back coat layers can be coated on the support in the present invention for writing property, antistatic property, transportability, curl resistance and the like. The backcoat layer can contain an appropriate combination of inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, pigments, curing agents, surfactants, and the like.

  When the coating liquid of the present invention is applied to a water-resistant support, it is preferable that corona discharge treatment, flame treatment, ultraviolet irradiation treatment, plasma treatment, subbing treatment, and the like are performed prior to coating.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. In addition, a part and% show a mass part and the mass%.

<< Preparation of recording sheet 1 >>
<Preparation of polyolefin resin-coated paper support>
A 1: 1 mixture of hardwood bleached kraft pulp (LBKP) and softwood bleached sulfite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. 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% was added and diluted with water to make a 1% slurry. This slurry was made with a long paper machine to a basis weight of 170 g / m ² , dried and conditioned to obtain a polyolefin resin-coated paper base paper. A polyethylene resin composition in which 10 parts of anatase-type titanium is uniformly dispersed is melted at 320 ° C. with respect to a resin of 100 parts of low density polyethylene having a density of 0.918 g / cm ³ , and the thickness is made 35 μm. Extrusion coating was performed, and the coating was extrusion-coated using a cooling roll that had been processed with a finely roughened surface to obtain a surface. Melted at similarly 320 ° C. The blend resin composition of the low density polyethylene resin 30 parts of a density 0.962 g / cm 70 parts high density polyethylene resin of ³ and a density 0.918 g / cm ³ on the other surface, the thickness Extrusion coating was carried out to a thickness of 30 μm, and extrusion coating was performed using a cooling roll that had been roughened to obtain a back surface.

The surface of the polyolefin resin-coated paper support was subjected to high-frequency corona discharge treatment, and then an undercoat layer having the following composition was applied and dried so that the amount of gelatin adhered was 60 mg / m ² .
<Underlayer>
Gelatin 100 parts Sulfosuccinic acid-2-ethylhexyl ester salt 2 parts Chrome alum 8 parts

On the above support, the ink receiving layer coating liquid (A) having the following composition and the uppermost ink receiving layer coating liquid (B) were applied in a moisture amount, and the coating liquid (A) was 170 g / m. ^{2 The} coating solution (B) was 20 g / m ² and was applied simultaneously by the slide bead coating method shown in FIG. The coating speed is 100 m / min.

<Ink-receiving layer coating solution A>
Gas phase method silica dispersion (as gas phase method silica solid content) 100 parts polyvinyl alcohol 23 parts (saponification degree 88%, average polymerization degree 3500)
Boric acid 4 parts Nonionic surfactant 0.3 parts (Polyoxyethylene alkyl ether)
It adjusted with water so that the density | concentration of a vapor-phase method silica might be 8%.

<Production of vapor phase silica dispersion>
After adding 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) and 100 parts of vapor phase process silica (average primary particle diameter 7 nm, specific surface area 300 m ² / g) to water to prepare a preliminary dispersion, a high-pressure homogenizer To prepare a silica dispersion having a solid concentration of 20%. The average secondary particle size was 100 nm.

<Ink-receiving layer coating solution B>
Wet process silica dispersion (as wet process silica solids) 100 parts boric acid 4 parts polyvinyl alcohol 50 parts (saponification degree 88%, average polymerization degree 3500)
Nonionic surfactant 0.3 parts (polyoxyethylene alkyl ether)
It adjusted with water so that the density | concentration of the wet method silica might be 6%.

<Preparation of wet method silica dispersion>
Wet method silica (P78A manufactured by Mizusawa Chemical Industry Co., Ltd., average secondary particle size 3 μm) 100 parts was added to water and dispersed with a high-speed homomixer to produce a silica dispersion having a solid concentration of 20%.

  When the above-mentioned coating liquids A and B were simultaneously applied in multiple layers, the following auxiliary liquid prepared in advance was supplied to both ends of the coating liquid flowing down the slide surface at a flow rate of 2 ml / min. The supply positions are 7, 8, and 9 in FIG. Moreover, it apply | coated without supplying auxiliary liquid as a comparative manufacture example.

<Auxiliary liquid>
Auxiliary liquid A; 2% aqueous polyvinyl alcohol solution Auxiliary liquid B; 4% dipropylene glycol aqueous solution Auxiliary liquid C; water

  Each of the coatings was continuously applied under the above conditions, and the coating time was observed when both ends of the uppermost layer were fixed and either one of the ends contracted inward to narrow the coating width. The results are shown in Table 1.

  As can be seen from the above results, stable continuous application for a long time becomes possible by using the production method of the present invention.

On the polyolefin resin-coated paper support of Example 1, the following ink-receiving layer coating liquid (C) and uppermost ink-receiving layer coating liquid (D) were each 180 g / m ^{2 in} terms of moisture application amount. At 22 g / m ² , simultaneous multilayer coating was performed by the slide bead coating method shown in FIG. The coating speed is 120 m / min.

<Ink-receiving layer coating solution C>
Vapor phase silica dispersion (as solid phase of vapor phase method silica) 50 parts Wet method silica finely divided dispersion (as solid content of wet method silica) 50 parts Boric acid 3 parts Polyvinyl alcohol 19 parts (Saponification degree 88% , Average degree of polymerization 3500)
Nonionic surfactant 0.2 parts (polyoxyethylene alkyl ether)
It adjusted with water so that the density | concentration of a silica might be set to 9.5%.

<Ink-receiving layer B coating solution>
Gas phase silica dispersion (as solid phase of gas phase silica) 100 parts Boric acid 3 parts Polyvinyl alcohol 17 parts (saponification degree 88%, average polymerization degree 3500)
Nonionic surfactant 0.2 parts (polyoxyethylene alkyl ether)
It adjusted with water so that the density | concentration of a gaseous-phase method silica might be set to 9%.

  The vapor phase silica dispersion was prepared by the same production method as in Example 1. A finely pulverized dispersion of wet-process silica was produced as follows.

<Wet process silica finely pulverized dispersion>
Dimethyldiallylammonium chloride homopolymer (molecular weight 9,000, 4 parts) and precipitated silica (average primary particle diameter 15 nm, average secondary particle diameter 18 μm, oil absorption 180 ml / 100 g, 100 parts) are added to water and sawtooth A pre-dispersion was prepared using a blade-type disperser (blade peripheral speed 20 m / sec). Next, the obtained preliminary dispersion was passed once through a bead mill under the conditions of a zirconia bead having a diameter of 0.3 mm, a filling rate of 80 vol%, and a disk peripheral speed of 10 m / sec. A silica dispersion having a secondary particle size of 200 nm was obtained.

  When simultaneously applying the above coating liquids A and B, the auxiliary liquid used in Example 1 was supplied to both ends of the coating liquid flowing down the slide surface at a flow rate of 1 ml / min. The supply positions are 7, 8, and 9 in FIG. Moreover, it apply | coated without supplying auxiliary liquid as a comparative manufacture example. The continuous application time was observed as in Example 1. The results are shown in Table 2.

  As can be seen from the above results, stable continuous application for a long time becomes possible by using the production method of the present invention.

The top view of one Embodiment of the slide hopper coating device used for the slide bead coating system used for this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front bar 2 Second bar 3 Third bar 4 Back bar 1a, 2a, 3a, 4a Sliding surface 1b, 2b, 3b Slit 5 Coating width regulating plate 6 Lip tip 7, 8, 9 Auxiliary liquid supply position

Claims (1)

A method for producing an ink jet recording material, which is applied on a support using a slide hopper type coating apparatus so that an ink receiving layer mainly containing inorganic fine particles is an uppermost layer, comprising : Immediately after the topmost coating liquid starts flowing down on the slide surface of the slide hopper type coating apparatus, the concentration of the inorganic fine particles is 5% by mass or more, and the moisture coating amount is 30 g / m ² or less. A method for producing an inkjet recording material, comprising supplying an aqueous solution containing polyvinyl alcohol or dipropylene glycol at a flow rate of 10 ml / min or less per side to both ends in the width direction on the more upstream side.

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