JP4657961B2 - Coating liquid for ink jet recording medium and ink jet recording medium - Google Patents

Description

  The present invention relates to a coating liquid for an ink jet recording medium having good production suitability containing fine silica particles dispersed therein, and an ink jet recording medium using the same.

  The inorganic fine particle dispersion is usually prepared by first dispersing (premixing) inorganic fine particles in a dispersion medium such as water, an organic solvent, or a mixture thereof to prepare a fine particle slurry, and then dispersing the fine particle slurry into a dispersing machine such as a sand mill or a ball mill. Can be prepared by secondarily dispersing.

  In a dispersion liquid in which inorganic fine particles such as silica fine particles are dispersed, it is important that the dispersion state is stable (dispersion stability). However, the fine particles are likely to aggregate in the liquid and easily increase in viscosity. The increase in viscosity tends to become noticeable as the concentration of fine particles in the liquid increases, and the technology that can maintain a stable dispersion state and viscosity while containing fine particles at a high concentration in the conventional technology, It has not necessarily been established.

For example, in an ink jet recording paper used for ink jet recording, inorganic fine particles are used in a layer on which ink is ejected. In general, a coating liquid for forming a layer containing dispersed inorganic fine particles is applied onto a support. Produced. However, the coating liquid containing dispersed inorganic fine particles tends to agglomerate the inorganic fine particles due to unstable dispersion and easily change in viscosity. Not only the occurrence of failure or streak-like application failure, but also performance degradation such as a decrease in image density, glossiness and a decrease in ink absorbency is caused.
Therefore, techniques for improving the dispersibility and dispersion stability of silica fine particles and other inorganic fine particles have been widely studied.

  As a technique related to the above, an example in which colloidal silica is mainly used as silica together with a nonionic surfactant having an HLB of 15 or more is disclosed (for example, see Patent Document 1), and there is no crack on the surface of the ink receiving layer. It has high gloss, excellent ink absorbability, and excellent dot reproducibility.

Further, there is an ink jet recording sheet that is configured by using both inorganic fine particles such as vapor phase method silica and a nonionic surfactant (for example, see Patent Documents 2 and 3). In these, the use of a water-soluble resin in the presence of a surfactant prevents surface failure and curling, or the use of a nonionic surfactant having a cloud point of 60 ° C. or lower provides cracking and light resistance. It is said that it will be improved.
JP-A-7-137434 Japanese Patent Laid-Open No. 2003-200655 JP 2004-230760 A

  However, the above-described conventional technology alone suppresses an increase in viscosity when a composition in which a binder component coexists when finely divided silica particles are used, and further improves the dispersion stability of the dispersed particles. Is not enough.

  In particular, improving the concentration of silica particles or the like in a dispersion liquid can be a basic technique for increasing the coating speed in that the concentration of the coating liquid can be increased and the drying load during coating and drying can be reduced. On the other hand, when the concentration of the dispersion of fine particles having a small particle diameter is increased, in general, the dispersion tends to aggregate and difficult to disperse, and even if it can be dispersed, the viscosity of the dispersion increases remarkably. When applying, there is a problem that the application cannot be performed satisfactorily.

  The present invention has been made in view of the above, and an object thereof is to provide a coating liquid for an ink jet recording medium having low viscosity and excellent dispersion stability after dispersion, and an ink jet recording medium having excellent ozone resistance. It is an object to achieve the object.

Specific means for achieving the above object are as follows.
<1> A coating liquid for an ink jet recording medium used for forming an ink receiving layer of an ink jet recording medium that receives ink and records an image, and at least a gas phase method silica having a primary particle diameter of 20 nm or less; A nonionic surfactant having a hydrophilic binder, a lipophilic chain having 13 or less carbon atoms including a branched structure, a polyoxyalkylene chain as a hydrophilic chain, and an HLB of 14.0 or more, and a water-soluble A polyvalent metal salt, wherein the content of the nonionic surfactant is 0.2% by mass or more and 5% by mass or less based on the mass of the vapor phase silica, and the water-soluble polyvalent metal salt It is a coating liquid for inkjet recording media whose content is 0.1 mass% or more and 20 mass% or less with respect to the mass of the said vapor phase method silica.
<2> The inkjet recording medium coating liquid according to <1>, wherein the water-soluble polyvalent metal salt is zirconyl acetate.
< 3 > The coating liquid for inkjet recording media according to <1> or <2> , further comprising a polymer having a polydiallyldimethylammonium chloride structure.

< 4 > The inkjet recording medium coating liquid according to any one of <1> to < 3 >, wherein the hydrophilic binder is polyvinyl alcohol having a saponification degree of 90% or less.
< 5 > The inkjet recording medium coating solution according to any one of <1> to < 4 >, further comprising a cation-modified latex resin.
< 6 > In an ink jet recording medium having an ink receiving layer on a support, the ink receiving layer includes at least gas phase method silica having a primary particle diameter of 20 nm or less, a hydrophilic binder, and a carbon number including a branched structure. 13 has the following lipophilic chain having a polyoxyalkylene chain as a hydrophilic chain comprising a nonionic surfactant having an HLB is 14.0 or more, and a water-soluble polyvalent metal salt, wherein the non-ionic The content of the surfactant is 0.2% by mass or more and 5% by mass or less with respect to the mass of the gas phase method silica, and the content of the water-soluble polyvalent metal salt is equal to the mass of the gas phase method silica. In contrast, the inkjet recording medium is 0.1% by mass or more and 20% by mass or less.
< 7 > The inkjet recording medium according to < 6 >, wherein the water-soluble polyvalent metal salt is zirconyl acetate.

  According to the present invention, it is possible to provide an ink jet recording medium coating solution having a low viscosity and excellent dispersion stability after dispersion, and an ink jet recording medium having a uniform film and excellent ozone resistance.

  Hereinafter, the coating liquid for inkjet recording media and the inkjet recording medium of the present invention will be described in detail.

<Coating liquid for inkjet recording medium>
The inkjet recording medium coating liquid of the present invention is a coating liquid for coating and forming the ink receiving layer of an inkjet recording medium having an ink receiving layer on a support, and has at least a primary particle size of 20 nm or less. Comprising phase-phase silica, a hydrophilic binder, and a nonionic surfactant having a lipophilic chain having a carbon number of 13 or less including a branched structure and having an HLB of 14.0 or more. It can be constructed using other components.

-Gas phase method silica-
The coating liquid for an inkjet recording medium of the present invention contains at least one kind of vapor-phase process silica having a primary particle diameter of 20 nm or less. Among the silica particles, the structure using the fine particles having a primary particle diameter of gas phase method silica of 20 nm or less can form a structure with a large porosity when a film (layer) is formed, and the liquid absorption It is possible to effectively improve the characteristics and to record an image with high gloss and high density and tightness.

In the present invention, the primary particle size of the vapor phase silica is 20 nm or less. When the primary particle diameter exceeds 20 nm, when a film (layer) is formed, gloss when printed, light scattering is likely to occur, image density is lowered and tightening is eliminated, and photographic-like image quality is obtained. It cannot be obtained. The lower limit of the primary particle diameter is not particularly limited, but is about 1 nm.
Among these, from the viewpoint of increasing glossiness and image density, the primary particle diameter is preferably 10 nm or less, more preferably 5 to 10 nm, and particularly preferably 6 to 9 nm.

  The “primary particle diameter” in the present invention is an average particle diameter calculated by measuring the particle size distribution of inorganic fine particles by observation with a transmission electron microscope.

  Here, the vapor phase silica is a particle obtained by a dry method (vapor phase method) with respect to a wet method particle (hydrous silica). The gas phase method is mainly a method by high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced and vaporized by an arc in an electric furnace and oxidized with air. This is a method of obtaining anhydrous silica by (arc method).

Vapor phase silica is different from hydrous silica in the density of silanol groups on the surface, the presence or absence of vacancies, etc., and exhibits different properties.For example, when forming a film, it forms a three-dimensional structure with high porosity. Suitable for The reason for this is not clear, but in the case of hydrous silica, the density of silanol groups on the surface of the fine particles is 5 to 8 / nm ² and many silica fine particles tend to aggregate tightly, whereas in the case of gas phase method silica, Since the density of silanol groups is 2 to 3 / nm ² and is small, it is presumed that sparse soft agglomeration (flocculate) results, resulting in a structure having a high porosity.

  Since vapor phase silica has a particularly large specific surface area, when a film is formed using a preparation liquid containing vapor phase silica, the formed film has high liquid absorption and retention efficiency. Since the refractive index is low, it is possible to impart transparency to the film by dispersing to an appropriate particle size. For example, when an image is formed by applying colored ink, a high color density and good color developability can be obtained. Can do. The transparency of the film is important not only for applications that require transparency, such as OHP, but also for obtaining high color density and good color development gloss even when applied to recording sheets such as photo glossy paper. It is.

  Specifically, the coating liquid for an inkjet recording medium is prepared by, for example, preparing a fine particle dispersion containing vapor phase silica in advance and adding other components such as a hydrophilic binder and a crosslinking agent to the prepared silica dispersion. Can be prepared. By applying (preferably applying) this coating liquid for inkjet recording medium onto a support, an inkjet recording medium can be produced.

The content of the vapor phase method silica in the coating liquid for inkjet recording medium is preferably in a range where the solid content concentration is 60% by mass or higher with respect to the total mass of the coating liquid for inkjet recording medium.
The solid content (mass) concentration of the vapor phase silica with respect to the total mass of the coating liquid for inkjet recording medium is the solid content (mass) relative to the solid content (mass) when the coating liquid for inkjet recording medium is completely dried. It is the ratio of the mass which remained except gas phase method silica from.

In addition to vapor phase silica, other inorganic fine particles, for example, silica fine particles other than vapor phase silica (colloidal silica, hydrous silica fine particles, etc.), titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, Talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, zinc oxide, zinc hydroxide, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, yttrium oxide, etc. as appropriate You may use together.
When the vapor phase silica and the other inorganic fine particles are used in combination, the amount of the vapor phase silica is preferably 60% by mass or more, more than 70% by mass with respect to the total amount of the vapor phase silica and the other inorganic fine particles. Is more preferable.

-Hydrophilic binder-
The coating liquid for inkjet recording media of the present invention contains at least one hydrophilic binder (hereinafter sometimes referred to as “the hydrophilic binder according to the present invention”). The ink receiving layer for receiving ink preferably has a porous structure, and can be formed into a porous structure by using a hydrophilic binder together with the vapor phase silica.

Examples of the hydrophilic binder include a polyvinyl alcohol resin that is a resin having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl. Alcohol, polyvinyl acetal, etc.], cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.], Chitins, chitosans, starch, resins having an ether bond [polyethylene oxide (PEO), Polypropylene oxide (PPO), polyethylene glycol (PEG), poly ether (PVE)], and resins having carbamoyl groups [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like.
Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.

From the viewpoint of ink absorptivity when the ink receiving layer is formed, among the hydrophilic binders, polyvinyl alcohol resins, cellulose resins, resins having an ether bond, resins having a galvamoyl group, resins having a carboxy group, And at least one selected from gelatins is more preferable.
Among these, polyvinyl alcohol (PVA) is particularly preferable.

  The saponification degree of polyvinyl alcohol (PVA) is preferably 90% or less, more preferably 75 to 90 mol%, still more preferably 77 to 90 mol%, particularly preferably 80 to 90 mol%, from the viewpoint of color density. It is.

  Moreover, as a polymerization degree of polyvinyl alcohol (PVA), from a viewpoint of obtaining sufficient film | membrane intensity | strength, 1400-5000 are preferable and 2300-4000 are more preferable. Polyvinyl alcohol having a polymerization degree of less than 1400 and a polymerization degree of 1400 or more may be used in combination.

The content of the hydrophilic binder in the ink jet recording medium coating liquid is such that when the ink-receiving layer is applied and formed, the film strength is prevented from being reduced due to the insufficient hydrophilic binder content and cracking during drying is prevented. From the viewpoint of preventing the ink from being reduced due to the void being easily blocked by the excessive content and the void ratio being reduced, the total solid content contained in the coating liquid for inkjet recording media The content is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass.
The silica fine particles and the hydrophilic binder may each be a single material or a mixed system of a plurality of materials.

  In addition to unmodified polyvinyl alcohol (PVA), the polyvinyl alcohol includes cation-modified PVA, anion-modified PVA, silanol-modified PVA, and other polyvinyl alcohol derivatives. Polyvinyl alcohol may be used alone or in combination of two or more.

The PVA has a hydroxyl group in its structural unit, and this hydroxyl group and the silanol group on the surface of the silica fine particle form a hydrogen bond, and it is easy to form a three-dimensional network structure in which the secondary particle of the silica fine particle is a chain unit. To do. It is considered that an ink receiving layer having a porous structure with a high porosity can be formed by forming such a three-dimensional network structure.
In the ink jet recording medium obtained by the present invention, the porous ink receiving layer obtained as described above absorbs ink rapidly by capillary action, and forms dots with good roundness without ink bleeding. can do.

-Nonionic surfactant-
The inkjet recording medium coating liquid of the present invention has at least one nonionic surfactant having a lipophilic chain having 13 or less carbon atoms including a branched structure and having an HLB of 14.0 or more (hereinafter referred to as “the present invention”). It may be referred to as a “nonionic surfactant”. By including this surfactant, it is possible to suppress an increase in viscosity when fine particles of vapor-phase method silica particles are contained together with a hydrophilic binder, and to effectively improve the dispersion stability of silica fine particles in a dispersed state. Furthermore, it is effective for improving the ozone resistance of an image when an image is recorded by applying ink to the ink receiving layer.

The nonionic surfactant according to the present invention has a lipophilic chain having 13 or less carbon atoms including a branched structure. When the lipophilic chain has a branched structure, it is effective for preventing the viscosity of the coating liquid from being increased as compared with a linear structure having the same carbon number. It is difficult to increase the viscosity of the liquid, and dispersion stability with stable viscosity can be secured. In other words, when the lipophilic chain has more than 13 carbon atoms, the coating solution is thickened and stable dispersibility cannot be obtained, and it is also disadvantageous in terms of ozone resistance.
From the viewpoint of the safety of surfactants, straight-chain surfactants having 12 and 13 carbon atoms are often highly aquatic biotoxic, but surfactants having 10 to 13 carbon atoms having a branched structure are aquatic. Biotoxicity tends to be significantly lower.
The number of carbon atoms in the lipophilic chain is preferably in the range of 6 to 13, more preferably in the range of 6 to 11.

  In the present invention, a nonionic surfactant having a HLB of 14.0 or more is used among the nonionic surfactants. If the HLB is less than 14.0, the coating solution is thickened, stable dispersibility cannot be obtained, and it is disadvantageous in terms of ozone resistance. The HLB value can be arbitrarily selected within the range of 14.0 or more. However, if the HLB exceeds 19, the coating solution may thicken depending on the composition and the like. The following is preferable, and more preferably 14 or more and 16 or less.

  In addition, HLB is a hydrophilic lipophilic balance (Hydrophile-Lipophile Balance), and is a value showing the grade of the affinity to water and oil (an organic compound insoluble in water) of surfactant. The HLB value is described in, for example, “Surfactant Handbook” (Tokiyuki Yoshida, Shinichi Shindo, Yoshiyoshi Yamanaka, published by Engineering Book Co., Ltd. 1987).

  Specific examples of the nonionic surfactant according to the present invention include polyoxyalkylene isotridecyl ethers such as polyoxyethylene isotridecyl ether, polyoxyalkylene branched decyl ethers, polyoxyethylene isodecyl ethers and the like. Further, among the surfactants described in the above-mentioned “Surfactant Handbook”, the surfactant has a lipophilic chain having 13 or less carbon atoms including a branched structure, and has an HLB of 14.0 or more. Things can be mentioned.

  Commercially available nonionic surfactants may also be used, for example, Neugen XL-100, XL140, XL160, XL400, XL400, SD110, SD80, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. SD150, SD300, SD400, Neugen TDS-120, TDS200D, TDS500F, Neugen TDX120D, etc. can be used.

  As content in the coating liquid for inkjet recording media of the nonionic surfactant based on this invention, 0.2-5 mass% is preferable with respect to vapor-phase-method silica, and 0.3-3 mass% is more preferable. . When the content of the nonionic surfactant according to the present invention is within the above range, a coating liquid using fine silica fine particles and a hydrophilic binder can be prepared with a low viscosity, and the dispersion stability after dispersion can be improved. it can. It is also effective in improving the ozone resistance of recorded images.

-Polymer having polydiallyldimethylammonium chloride structure-
The coating liquid for an inkjet recording medium of the present invention can be suitably configured using at least one polymer having a polydiallyldimethylammonium chloride structure. This polymer is effective for fixing the applied ink and improving the image density, and for imparting the dispersion stability of the vapor phase silica.

  Specific examples of the polymer having a polydiallyldimethylammonium chloride structure include diallyldimethylammonium chloride-2 sulfur oxide copolymer, diallyldimethylammonium chloride-acrylamide copolymer, diallyldimethylammonium chloride-diallylamine hydrochloride copolymer, diallyl Examples thereof include dimethylammonium chloride-maleic acid-sulfur dioxide copolymer.

  The molecular weight of the “polymer having a polydiallyldimethylammonium chloride structure” is preferably 1000 to 50000, more preferably 3000 to 15000 in terms of weight average molecular weight.

  The content of the “polymer having a polydiallyldimethylammonium chloride structure” in the coating liquid for an ink jet recording medium is preferably 1 to 30% by mass, more preferably 2 to 15% by mass with respect to the vapor phase silica. 10 mass% is especially preferable. When the content of this polymer is within the above range, it is effective for improving dispersibility, dispersion stability, and image density.

-Water-soluble polyvalent metal salt-
The coating liquid for inkjet recording media of the present invention contains at least one water-soluble polyvalent metal salt. By using the water-soluble polyvalent metal salt, the water resistance and bleeding resistance of the recorded image and the dispersion stability of the vapor phase silica can be improved.

Examples of the water-soluble polyvalent metal salt include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, magnesium, tungsten, and molybdenum.
Specifically, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride Dicopper, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate Ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, ferrous bromide, ferric chloride Ferrous, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate hexahydrate , Zinc sulfate, zirconium acetate, zirconium chloride, zirconium chloride octahydrate, hydroxy zirconium chloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate Sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, and the like.

  The water-soluble polyvalent metal salt is preferably at least one selected from water-soluble aluminum compounds, zirconium compounds and titanium compounds.

  Examples of the water-soluble aluminum compound include, as inorganic salts, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like. Furthermore, there is a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer. In particular, a basic polyaluminum hydroxide compound is preferable.

The basic polyaluminum hydroxide compound is represented by the following formula 1, 2 or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [ Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , and the like are water-soluble polyaluminum hydroxides that stably contain basic and high-molecular polynuclear condensed ions.

[Al ₂ (OH) _n Cl _6-n ] _m Formula 1
[Al (OH) ₃ ] _n AlCl ₃ Formula 2
Al _n (OH) _m Cl _(3n-m) 0 <m <3n Formula 3

  About these, as water treatment agent under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., under the name of polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd., and from Riken Green Co., Ltd. It is marketed by Purakem WT for the same purpose from other manufacturers, and various grades can be easily obtained. In the present invention, these commercially available products can be used as they are, but there are some which have an inappropriately low pH, and in that case, the pH can be appropriately adjusted and used.

  The water-soluble zirconium compound is not particularly limited and various compounds can be used. For example, zirconyl acetate, zirconium chloride, zirconium oxychloride, hydroxy zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium carbonate -Ammonium, zirconium carbonate and potassium, zirconium sulfate, zirconium fluoride compounds and the like. Zirconyl acetate is particularly preferable.

  The water-soluble titanium compound is not particularly limited and various compounds can be used. Examples thereof include titanium chloride and titanium sulfate.

  Some of these compounds have an inappropriately low pH. In that case, the pH can be appropriately adjusted and used. In the present invention, the term “water-soluble” means that 1% by mass or more dissolves in water at room temperature and normal pressure.

In the case of using a water-soluble polyvalent metal salt, it is particularly preferable that at least one of them is zirconyl acetate from the viewpoint of imparting a bleeding suppression effect to a wider range of dyes. In the case of using zirconyl acetate temple, the content of zirconyl acetate in the ink receiving layer is preferably 0.3 g / m ² or less, 0.01~0.02g / m ² is more preferable.

  When zirconyl acetate is used, it is preferable from the viewpoint of viscosity stability of the coating solution that zirconyl acetate is previously contained in the fine particle dispersion, and then the dispersion and binder are mixed. More preferably, the dispersion treatment is performed in the presence of zirconyl acetate in advance in the liquid containing the fine particles before the dispersion treatment.

Although the water-soluble polyvalent metal salt can be used alone, it is preferable to use two or more kinds in combination.
The content of the water-soluble polyvalent metal salt in the coating liquid for inkjet recording media is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the mass of the vapor phase silica.

-Cation-modified latex resin-
The coating liquid for an ink jet recording medium of the present invention can be suitably configured using at least one kind of cation-modified latex resin (hereinafter sometimes simply referred to as “latex resin”). This latex resin functions as a mordant for fixing the applied ink, and is effective in improving the image density and suppressing bleeding of the print sample over time.

  The latex resin refers to a colloidal dispersion having a volume average particle diameter of 0.001 to 0.1 μm or an emulsion liquid having a volume average particle diameter of 0.1 to 10 μm.

  The latex resin includes a “cation-modified polymer” having a volume average particle diameter of 0.001 to 0.1 μm (preferably 0.001 to 0.05 μm, more preferably 0.001 to 0.01 μm). A colloidal dispersion is preferred.

  More specifically, the “cation-modified polymer” contained in the latex resin in the present invention is, for example, a polyaddition system or a heavy compound having a cationic group such as a primary to tertiary amino group or a quaternary ammonium group. Examples include condensed polymer compounds.

  Examples of the vinyl polymerization polymer effective as the “cation-modified polymer” include polymers obtained by polymerizing the following vinyl monomers. That is, acrylic acid esters and methacrylic acid esters (the ester group is an alkyl group or aryl group which may have a substituent, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n- Butyl group, sec-butyl group, tert-butyl group, hexyl group, 2-ethylhexyl group, tert-octyl group, 2-chloroethyl group, cyanoethyl group, 2-acetoxyethyl group, tetrahydrofurfuryl group, 5-hydroxypentyl group Cyclohexyl group, benzyl group, hydroxyethyl group, 3-methoxybutyl group, 2- (2-methoxyethoxy) ethyl group, 2,2,2-tetrafluoroethyl group, 1H, 1H, 2H, 2H-perfluorodecyl Group, phenyl group, 2,4,5-tetramethylphenyl group, 4-chlorophenyl group, etc.);

  Vinyl esters, specifically, aliphatic carboxylic acid vinyl esters which may have a substituent (for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl Chloroacetate, etc.), optionally substituted aromatic carboxylic acid vinyl ester (for example, vinyl benzoate, vinyl 4-methylbenzoate, vinyl salicylate, etc.);

  Acrylamides, specifically, acrylamide, N-monosubstituted acrylamide, N-disubstituted acrylamide (the substituent is an alkyl group, aryl group, silyl group which may have a substituent, such as a methyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, tert-octyl group, cyclohexyl group, benzyl group, hydroxymethyl group, alkoxymethyl group, phenyl group, 2,4,5-tetramethylphenyl group , 4-chlorophenyl group, trimethylsilyl, etc.);

  Methacrylamide, specifically, methacrylamide, N-monosubstituted methacrylamide, N-disubstituted methacrylamide (substituents are optionally substituted alkyl, aryl, silyl groups, for example , Methyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, tert-octyl group, cyclohexyl group, benzyl group, hydroxymethyl group, alkoxymethyl group, phenyl group, 2,4,5- Tetramethylphenyl group, 4-chlorophenyl group, trimethylsilyl, etc.);

  Olefins (for example, ethylene, propylene, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, etc.), styrenes (for example, styrene, methylstyrene, isopropylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, etc.) Vinyl ethers (for example, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxyethyl vinyl ether, etc.);

  Other vinyl monomers include crotonic acid ester, itaconic acid ester, maleic acid diester, fumaric acid diester, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, N-vinyl oxazolidone, N-vinyl pyrrolidone, methylene malon nitrile, diphenyl Examples include 2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxyethyl phosphate, dioctyl-2-methacryloyloxyethyl phosphate, and the like.

  In addition to the above, examples of the monomer having a cationic group include monomers having a tertiary amino group such as dialkylaminoethyl methacrylate and dialkylaminoethyl acrylate.

Examples of the polyurethane applicable to the “cation-modified polymer” include polyurethanes synthesized by a polyaddition reaction using various combinations of the following diol compounds and diisocyanate compounds.
Specific examples of the diol compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 2,2 -Dimethyl-1,3-propanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 3,3-dimethyl-1,2-butanediol, 2 -Ethyl-2-methyl-1,3-propanediol, 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol 2,2-diethyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 1,7-heptane All, 2-methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1,3-hexanediol, 1,2-octanediol, 1, 8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol, hydroquinone, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol (average molecular weight = 200,300,400,600,1000,1500,4000), polypropylene glycol (average molecular weight = 200,400,1000), polyester polyol, 4,4′-dihydroxy-diphenyl-2,2-propane, 4,4 ′ -Dihydroxyphenyls Examples include ruphone and polycarbonate polyol.

Examples of the diisocyanate compound include methylene diisocyanate, ethylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, 1, 5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 3,3′-dimethylbiphenylene diisocyanate, 4,4′-biphenylene diisocyanate, dicyclohexylmethane diisocyanate , Methylenebis (4-cyclohexylisocyanate) and the like.

Examples of the cationic group contained in the polyurethane having a cationic group include cationic groups such as primary to tertiary amines and quaternary ammonium salts. The polymer used for the latex in the present invention is preferably a urethane resin having a cationic group such as a tertiary amine and a quaternary ammonium salt.
A polyurethane having a cationic group can be obtained, for example, by using a polyurethane in which a cationic group is introduced in the synthesis of polyurethane. In the case of a quaternary ammonium salt, a polyurethane containing a tertiary amino group may be quaternized with a quaternizing agent.

  The diol compound and diisocyanate compound that can be used for the synthesis of the polyurethane may be used alone or in various ways (for example, adjustment of the glass transition temperature (Tg) of the polymer and improvement of solubility, Depending on the compatibility with the binder, improvement of the stability of the dispersion, etc., two or more of them can be used in any proportion.

Furthermore, examples of the polyester applicable to the “cation-modified polymer” include polyesters synthesized by a polycondensation reaction using various combinations of the following diol compounds and dicarboxylic acid compounds.
Examples of the dicarboxylic acid compound include oxalic acid, malonic acid, succinic acid, glutaric acid, dimethylmalonic acid, adipic acid, pimelic acid, α, α-dimethylsuccinic acid, acetone dicarboxylic acid, sebacic acid, and 1,9-nonanedicarboxylic acid. Acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, phthalic acid, isophthalic acid, terephthalic acid, 2-butyl terephthalic acid, tetrachloroterephthalic acid, acetylenedicarboxylic acid, poly (ethylene terephthalate) dicarboxylic acid, 1,2- Examples include cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, ω-poly (ethylene oxide) dicarboxylic acid, and p-xylylene dicarboxylic acid.

  When performing the polycondensation reaction with the diol compound, the dicarboxylic acid compound may be used in the form of an alkyl ester of dicarboxylic acid (for example, dimethyl ester) and an acid chloride of dicarboxylic acid, or maleic anhydride, anhydrous You may use in the form of an acid anhydride like succinic acid and phthalic anhydride.

  As the diol compound, the same compounds as the diols exemplified in the above polyurethane can be used.

  The polyester having a cationic group can be obtained by synthesis using a dicarboxylic acid compound having a cationic group such as a primary, secondary, tertiary amine or quaternary ammonium salt.

  The diol compounds, dicarboxylic acids, and hydroxycarboxylic acid ester compounds used in the synthesis of the polyester may be used alone or in various ways (for example, adjustment of the glass transition temperature (Tg) of the polymer). Or two or more of them may be mixed and used in an arbitrary ratio depending on the solubility, compatibility with the dye, and stability of the dispersion.

  The content of the cationic group in the “cation-modified polymer” is preferably 0.1 to 5 mmol / g, and more preferably 0.2 to 3 mmol / g. In addition, when there is too little content of the said cationic group, the dispersion stability of a polymer will become small, and when too large, compatibility with a binder will fall.

  The “cation-modified polymer” is preferably a polymer having a cationic group such as a tertiary amino group or a quaternary ammonium base, and particularly preferably a urethane resin having a cationic group as described above.

  When the “cationically modified polymer” is used in the ink receiving layer, the glass transition temperature is particularly important. In order to suppress bleeding over time after forming an image by inkjet recording over a long period of time, it is preferable that the “cation-modified polymer” has a glass transition temperature of less than 50 ° C. Further, the “cation-modified polymer” having a glass transition temperature of 30 ° C. or lower is more preferable, and a glass transition temperature of 15 ° C. or lower is most preferable. When the glass transition temperature is 50 ° C. or higher, dimensional stability (curl) may be deteriorated. In addition, although there is no restriction | limiting in particular in the minimum of this glass transition temperature, in normal use, it is about -30 degreeC, and if lower than this, the manufacturability at the time of preparing an aqueous dispersion may fall.

  The weight average molecular weight (Mw) of the “cation-modified polymer” contained in the latex resin is usually preferably from 1,000 to 1,000,000, more preferably from 300,000 to 700,000. If the Mw is within the above range, a stable aqueous dispersion is likely to be obtained, the solubility does not decrease and the liquid viscosity does not increase, and the average particle size of the aqueous dispersion is reduced, particularly controlled to 0.05 μm or less. Easy to do.

  The content of the “cation-modified polymer” in the latex resin is preferably determined so as to be 0.1 to 30% by mass of the total solids constituting the ink receiving layer, and 0.3 to 20 % By mass is more preferable, and 0.5 to 15% by mass is most preferable. When the content is in the range of 0.1 to 30% by mass, the effect of improving bleeding with time can be sufficiently exerted, and the ratio of fine particles and binder components described later is reduced, and the ink absorbability to high-quality recording paper is reduced. There is no decline.

  The latex resin is a colloidal dispersion containing a cationic urethane resin having a volume average particle size of 30 nm or less, and the glass transition temperature of the cationic urethane resin is less than 50 ° C. Are particularly preferred.

  Commercially available products can be used as the latex resin, such as “Superflex 650”, “Superflex 620”, “Superflex 610”, “Superflex 600”, etc., manufactured by Daiichi Kogyo Seiyaku Co., Ltd. It is done.

Next, a method for preparing a latex resin in the present invention will be described.
In the present invention, the cation-modified latex resin is prepared by mixing the “cation-modified polymer” with an aqueous solvent, mixing additives as necessary, and finely pulverizing the mixed solution using a disperser. By doing so, it can be obtained as an aqueous dispersion. As a disperser used for obtaining the aqueous dispersion, various conventionally known dispersers such as a high-speed rotary disperser, an ultrasonic disperser, a colloid mill disperser, and a high-pressure disperser can be used. From the viewpoint of efficiently dispersing the lumpy fine particles, a high-pressure disperser is preferable.

  The high-pressure disperser (homogenizer) is described in detail in U.S. Pat. No. 4,533,254, JP-A-6-47264, etc., but as a commercially available apparatus, a gorin homogenizer (APV GAULIN INC.), Microfluidizer (MICROFLUIDEX INC.), Optimizer (Sugino Machine Co., Ltd.), etc. can be used. In recent years, a high-pressure homogenizer having a mechanism for atomizing in an ultrahigh-pressure jet stream as described in US Pat. No. 5,720,551 is particularly effective for emulsification dispersion in the present invention. DeBEE2000 (BEE INTERNATIONAL LTD.) Can be cited as an example of an emulsifier using this ultra-high pressure jet stream. Among these, a high-pressure jet disperser is particularly preferable because it is easy to obtain the single dispersibility of the fine particles in the present invention, the haze of the ink receiving layer can be reduced, and a high porosity can be obtained.

  Water, an organic solvent, or a mixed solvent thereof can be used as an aqueous solvent at the time of dispersion. Examples of the organic solvent that can be used for the dispersion include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene. It is done.

  The “cation-modified polymer” contained in the latex resin can be a naturally stable emulsified dispersion by itself, but a small amount of a dispersing agent is used in order to make the emulsified dispersion more quickly or more stable. (Surfactant) may be used. Surfactants used for such purposes include, for example, fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensates. , Anionic surfactants such as polyoxyethylene alkyl sulfates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene Nonionic surfactants such as alkylamines, glycerin fatty acid esters and oxyethyleneoxypropylene block copolymers are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred. Further, pages (37) to (38) of JP-A-59-157,636, Research Disclosure No. Those listed as surfactants described in 308119 (1989) can also be used.

  In order to stabilize immediately after emulsification, a water-soluble polymer can be added in combination with the surfactant. As the water-soluble polymer, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, polyacrylic acid, polyacrylamide or a copolymer thereof is preferably used. It is also preferable to use natural water-soluble polymers such as polysaccharides, casein, and gelatin.

  When the “cation-modified polymer” is dispersed in an aqueous medium by the emulsification dispersion method, it is particularly important to control the particle size. In order to increase color purity and color density when an image is formed by inkjet, it is necessary to reduce the average particle diameter of the “cation-modified polymer” in the aqueous dispersion.

  The amount of the latex resin used in the coating liquid for inkjet recording media is such that the amount of the “cation-modified polymer” is in the range of 0.5 to 15% by mass with respect to the vapor phase silica (mass). The amount is more preferably 2 to 10% by mass.

-Other ingredients-
In addition to the above components, the coating liquid for inkjet recording media of the present invention may further contain a crosslinking agent, other cationic polymers, and other components.

(Crosslinking agent)
The coating liquid for an inkjet recording medium of the present invention preferably contains a gas phase method silica and a hydrophilic binder, and further contains a crosslinking agent capable of cross-linking the hydrophilic binder. An embodiment having a porous structure in which a binder is cured by a crosslinking reaction with a crosslinking agent capable of crosslinking is preferable.

As the cross-linking agent, a suitable one may be selected as appropriate in relation to the hydrophilic binder contained in the ink receiving layer, and among them, a boron compound is preferable in that the cross-linking reaction is rapid. Examples of the boron compound include borax, boric acid, borate (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diboric acid). Salt (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na _{2 B 4 O 7 · 10H 2 O} ), can be mentioned five borate _{(e.g., KB 5 O 8 · 4H 2} O, Ca 2 B 6 O 11 · 7H 2 O, CsB 5 O 5) or the like. of these, Borax, boric acid and borates are preferred because they can promptly cause a crosslinking reaction. Boric acid is particularly preferred, and it is most preferred to use them in combination with polyvinyl alcohol which is a hydrophilic binder.

  About content of a crosslinking agent, the range of 0.05-0.50 mass part is preferable with respect to 1.0 mass part of hydrophilic binders as stated above, and the range of 0.08-0.30 mass part is more. preferable. When the content of the cross-linking agent is within the above range, the hydrophilic binder can be effectively cross-linked and effective in preventing cracks and the like.

When gelatin is used as the hydrophilic binder, the following compounds other than the boron compound can also be used as the crosslinking agent.
For example, aldehyde compounds such as formaldehyde, glyoxal and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5- Active halogen compounds such as triazine and 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide) ), Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin; melamine resins (for example, methylolmelamine, alkylated methylolmelamine) ;Epoxy resin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983,611; carboximide compounds described in US Pat. No. 3,100,704; glycerol Epoxy compounds such as triglycidyl ether; ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; -Dioxane compounds such as dihydroxydioxane; metal-containing compounds such as titanium lactate, aluminum sulfate, chromium alum, potash alum, zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, and hydrazides such as adipic acid dihydrazide Compounds, low molecules or polymers containing two or more oxazoline groups.
A crosslinking agent may be used alone or in combination of two or more.

The cross-linking agent may be added to the inkjet recording medium coating liquid and / or the coating liquid for forming the adjacent layer of the ink receiving layer when the ink receiving layer is formed on the support. On the support coated with a coating solution containing a crosslinking agent, the coating solution for inkjet recording medium is coated, or the coating solution for inkjet recording medium containing no crosslinking agent is applied and dried, and then overcoated with the coating solution. For example, the crosslinking agent can be supplied to the ink receiving layer. From the viewpoint of production efficiency, it is preferable to add a cross-linking agent to the ink jet recording medium coating liquid or the coating liquid for forming the adjacent layer and supply the cross-linking agent simultaneously with the formation of the ink receiving layer. In particular, it is preferably contained in the coating liquid for ink jet recording media from the viewpoint of improving the image printing density and glossiness.
Moreover, as a density | concentration in the coating liquid for inkjet recording media of a crosslinking agent, 0.05-10 mass% is preferable, and 0.1-7 mass% is more preferable.

For example, the crosslinking agent can be suitably applied as follows. Here, a boron compound will be described as an example. That is,
When the ink receiving layer is a layer obtained by crosslinking and curing the coating layer coated with the coating liquid for ink jet recording medium (first liquid), the crosslinking curing is performed by (1) forming the coating layer by coating the first liquid. At the same time, or (2) during the dry coating of the coating layer formed by applying the first liquid and before the coating layer exhibits reduced-rate drying, or (3) applying the first liquid After the formed coating layer is dried, it can be carried out by applying a basic solution (second solution) having a pH of 7.1 or higher to the coating layer at any time. The boron compound as a crosslinking agent may be contained in at least one of the first liquid and the second liquid, and may be contained in both the first liquid and the second liquid.

(Other cationic polymers)
The coating liquid for an inkjet recording medium of the present invention may contain a cationic polymer other than the above “polymer having a polydiallyldimethylammonium chloride structure”.
As the other cationic polymer, a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic group is suitable, but a cationic non-polymer mordant can also be used.

  Examples of the other cationic polymer include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (mordant monomer), the mordant monomer and another monomer. (Hereinafter referred to as “non-mordant monomer”) is preferably a copolymer or condensation polymer. These may be in the form of water-soluble polymer or water-dispersible latex particles.

  Examples of the monomer (mordanting monomer) include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N , N-dimethyl-N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-N -P-vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-die Ru-N-benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-N -P-vinylbenzylammonium chloride;

Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate;

N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted with their anions.

  Specifically, for example, monomethyl diallyl ammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, triethyl- 2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl-2- (Methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylamino) ethyl Ammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) propylammonium chloride Triethyl-3- (acryloylamino) propylammonium chloride;

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate.
Other examples of the copolymerizable monomer include N-vinylimidazole and N-vinyl-2-methylimidazole.

In addition, allylamine, diallylamine, its derivatives, salts and the like can be used. Examples of such compounds include allylamine, allylamine hydrochloride, allylamine acetate, allylamine sulfate, diallylamine, diallylamine hydrochloride, diallylamine acetate, diallylamine sulfate, diallylmethylamine and salts thereof (for example, the salts include , Hydrochloride, acetate, sulfate, etc.), diallylethylamine, and salts thereof (for example, hydrochloride, acetate, sulfate, etc.). In addition, since these allylamines and diallylamine derivatives are inferior in polymerizability in the form of amines, they are generally polymerized in the form of salts and desalted as necessary.
In addition, a unit such as N-vinylacetamide, N-vinylformamide or the like, which is converted into a vinylamine unit by hydrolysis after polymerization, and a salt thereof can also be used.

The non-mordant monomer does not contain a basic or cationic moiety such as a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base, and does not show an interaction with a dye in an inkjet ink. Or the monomer which interaction is substantially small is said.
Examples of non-mordant monomers include (meth) acrylic acid alkyl esters; (meth) acrylic acid cycloalkyl esters such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl esters such as phenyl (meth) acrylate; Aralkyl esters such as meth) benzyl acrylate; aromatic vinyls such as styrene, vinyltoluene and α-methylstyrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; allyl esters such as allyl acetate; And halogen-containing monomers such as vinylidene chloride and vinyl chloride; vinyl cyanide such as (meth) acrylonitrile; olefins such as ethylene and propylene.

The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, such as methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Of these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable.
The non-mordant monomers can also be used singly or in combination of two or more.

  Further, other cationic polymers include polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethyleneimine, polyallylamine and derivatives thereof, polyamide-polyamine resin, cationized starch, dicyandiamide formalin condensate, dimethyl-2-hydroxy Propylammonium salt polymer, polyamidine, polyvinylamine, dicyan diamide-formalin polycondensate represented by dicyan-based chaotic resin, dicyanamide-diethylenetriamine polycondensate-typified polyamine-based chaotic resin, epichlorohydrin-dimethylamine addition polymer, (Meth) acrylate-containing polymer having quaternary ammonium base-substituted alkyl group in ester moiety, quaternary ammonium base-substituted alkyl Styryl polymers having a group may be mentioned as being also preferred.

  Specific examples include JP-A-48-28325, JP-A-54-74430, JP-A-54-124726, JP-A-55-22766, JP-A-55-142339, JP-A-60-23850, and JP-A-60-23851. 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122942, 60-235134 and JP-A-1-161236, as well as U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, Nos. 4282305 and 4450224, and No. 161236, No. 10-81064, No. 10-119423, No. 10-157277, No. 10-217601, No. 11-348409, JP-A No. 2001-138621, No. 2000-43401, No. 2000- 211235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090, 8-2091, 8-2093 No. 8-1744992, No. 11-192777, JP-A No. 2001-301314, JP-B No. 5-35162, No. 5-35163, No. 5-35164, No. 5-88846, JP-A No. 7-8846 118333, JP-A No. 2000-344990, Japanese Patent No. 2648847, No. 2666177, etc. Include those such as described in distribution. Among the above, a (meth) acrylate-containing polymer having a quaternary ammonium base in the ester portion is preferable.

  Among other cationic polymers, a cationic polymer having a weight average molecular weight of 200,000 or less and an I / O value of 3.0 or less is preferable from the viewpoint of preventing bleeding with time.

Another cationic polymer may be used in combination with one or more of the above-mentioned “polymers having a polydiallyldimethylammonium chloride structure”. Moreover, you may use together another cationic polymer, another organic mordant, and / or an inorganic mordant.
These other cationic polymers can be used within the content range of the “polymer having a polydiallyldimethylammonium chloride structure” described above.

(Other ingredients)
The coating liquid for inkjet recording media of the present invention is constituted using the following components as necessary. That is, for the purpose of suppressing the deterioration of the hue of the ink, it may contain various anti-fading agents such as various ultraviolet absorbers, antioxidants, and singlet oxygen quenchers.

  Examples of the ultraviolet absorber include cinnamic acid derivatives, benzophenone derivatives, benzotriazolylphenol derivatives, and the like. For example, α-cyano-phenyl cinnamate butyl, o-benzotriazole phenol, o-benzotriazole-p-chlorophenol, o-benzotriazole-2,4-di-t-butylphenol, o-benzotriazole-2,4 -Di-t-octylphenol etc. are mentioned. A hindered phenol compound can also be used as an ultraviolet absorber, and specifically, a phenol derivative in which at least one of 2-position or 6-position is substituted with a branched alkyl group is preferable.

  Moreover, a benzotriazole type ultraviolet absorber, a salicylic acid type ultraviolet absorber, a cyanoacrylate type ultraviolet absorber, an oxalic acid anilide type ultraviolet absorber, etc. can be used. For example, JP-A-47-10537, 58-111942, 58-21284, 59-19945, 59-46646, 59-109055, 63-53544. No. 36, Japanese Patent Publication No. 36-10466, No. 42-26187, No. 48-30492, No. 48-31255, No. 48-41572, No. 48-54965, No. 50-10726. No. 2,719,086, US Pat. No. 3,707,375, US Pat. No. 3,754,919, US Pat. No. 4,220,711, and the like. .

  A fluorescent brightening agent can also be used as an ultraviolet absorber, and examples thereof include a coumarin fluorescent brightening agent. Specifically, it is described in Japanese Patent Publication Nos. 45-4699 and 54-5324.

  Examples of the antioxidant include European Patent Publication No. 223739, Publication No. 309401, Publication No. 309402, Publication No. 310551, Publication No. 310552, Publication No. 4594416, Publication of German Patent No. 3435443, JP-A-54-48535, JP-A-60-107384, JP-A-60-107383, JP-A-60-125470, JP-A-60-125471, JP-A-60-125472, JP-A-60-287485. 60-287486, 60-287487, 60-287488, 61-160287, 61-185483, 61-2111079, 62-146678, 62-146680, 62-146679, 62-282885, JP same 62-262047, JP-same 63-051174, JP-same 63-89877, JP-same 63-88380, JP-same 66-88381, JP-same 63-113536 JP;

  JP-A-63-163351, JP-A-63-203372, JP-A-63-224989, JP-A-63-251282, JP-A-63-267594, JP-A-63-182484, JP-A-1-239282, JP-A-2-262654, JP-A-2-71262, JP-A-3-121449, JP-A-4-29185, JP-A-4-291684, JP-A-5-61166, JP-A-5-119449, 5-188687, 5-188686, 5-110490, 5-110437, 5-170361, JP 48-43295, 48-33212, Examples thereof include those described in U.S. Pat. Nos. 4,814,262 and 4,980,275.

  Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3 4, -tetrahydroquinoline, nickel cyclohexane acid, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 2-methyl-4-methoxy-diphenylamine, Examples include 1-methyl-2-phenylindole.

  These antioxidants may be used alone or in combination of two or more. The antioxidant may be water-solubilized, dispersed, emulsified, or included in microcapsules. The addition amount of the antioxidant is preferably in the range of 0.01 to 10% by mass of the coating liquid for inkjet recording media.

  The coating liquid for ink jet recording medium of the present invention may contain a high boiling point organic solvent for the purpose of preventing curling after the ink receiving layer is formed on the support. The high-boiling organic solvent is preferably water-soluble, and examples of the water-soluble high-boiling organic solvent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, diethylene glycol monobutyl ether (DEGMBE), Ethylene glycol monobutyl ether, glycerin monomethyl ether, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, tri Examples include alcohols such as ethanolamine and polyethylene glycol (weight average molecular weight of 400 or less). Diethylene glycol monobutyl ether (DEGMBE) is preferred.

  As content in the coating liquid for inkjet recording media of a high boiling point organic solvent, 0.05-1 mass% is preferable, Most preferably, it is 0.1-0.6 mass%.

Moreover, the coating liquid for inkjet recording media may contain acids, alkalis, etc. as various inorganic salts and pH adjusters for the purpose of enhancing the dispersibility of the vapor phase silica.
Furthermore, for the purpose of suppressing surface frictional charge or peeling charge, the metal oxide fine particles having electronic conductivity may contain various matting agents for the purpose of reducing the surface frictional characteristics.

<Inkjet recording medium>
The ink jet recording medium of the present invention has at least one ink receiving layer (ink receiving layer according to the present invention) on a support, and at least one of the ink receiving layers has a primary particle diameter of 20 nm or less. It is composed of vapor-phase process silica, a hydrophilic binder, and a nonionic surfactant having a lipophilic chain having 13 or less carbon atoms including a branched structure and having an HLB of 14.0 or more. . In addition to the above, the ink receiving layer may further contain other components.

  The ink receiving layer constituting the ink jet recording medium of the present invention has “gas phase method silica having a primary particle diameter of 20 nm or less”, “hydrophilic binder”, and “lipophilic chain having 13 or less carbon atoms including a branched structure”. The non-ionic surfactant having an HLB of 14.0 or higher ”is not particularly limited and may be formed by any known method.

  It is to be noted that “a gas phase method silica having a primary particle diameter of 20 nm or less”, “hydrophilic binder”, and “a lipophilic chain having a carbon number of 13 or less including a branched structure and an HLB of 14.0 or more” Details of the “ionic surfactant” are as described above, and preferred embodiments are also the same.

  The ink receiving layer according to the present invention can be most preferably produced using the above-described coating liquid for ink jet recording medium of the present invention. As described above, the ink receiving layer has “gas phase method silica having a primary particle diameter of 20 nm or less”, “hydrophilic binder”, and “lipophilic chain having 13 or less carbon atoms including a branched structure, Since it is formed using a “nonionic surfactant having an HLB of 14.0 or more”, an excellent surface-shaped ink receiving layer can be obtained, and an image having excellent ozone resistance can be recorded.

  The ink-receiving layer according to the present invention preferably has at least “gas phase method silica having a primary particle diameter of 20 nm or less” and “a lipophilic chain having 13 or less carbon atoms including a branched structure, and an HLB of 14.0. Ink-receiving layer prepared using a silica dispersion containing the above-mentioned nonionic surfactant "and optionally a" polymer having a polydiallyldimethylammonium chloride structure ", and the hydrophilic binder according to the present invention A coating layer coated with a coating solution for forming (first solution; preferably, the above-described coating solution for an ink jet recording medium of the present invention) is a layer obtained by crosslinking and curing. At the same time as one liquid is applied, or (2) before the coating layer is dried by the coating layer formed by applying the first liquid, or (3) the first liquid is applied. Dry the coating layer formed in After form, when one of the can be formed by applying pH7.1 more basic solution (second liquid) in the coating layer or coating.

  The cross-linking agent that crosslinks the oleophilic binder may be contained not only in the first liquid but also in the second liquid. The ink-receiving layer that has been cross-linked and cured has advantages such as ink absorptivity and prevention of film cracking. In addition to this, it is also preferable in terms of improving the appearance such as repelling failure.

  The latex resin is used by being added to at least one of the first liquid (preferably an ink jet recording medium coating liquid) and the second liquid (basic solution). From the viewpoint of being sufficiently mixed with the conductive binder and effectively preventing bleeding over time, an embodiment in which it is contained in the first liquid (coating liquid containing vapor phase silica and a hydrophilic binder) is preferable. At this time, it is not always necessary to contain all of the latex resin in the first coating liquid, and it is also effective to contain at least a part of the latex resin in the second liquid, thereby effectively preventing bleeding over time. be able to. Also preferred is an embodiment in which at least a part of the latex resin is contained in both the first liquid and the second liquid.

  The mordant is preferably present so that the thickness of the portion where the mordant is present from the surface of the ink receiving layer is 10 to 60% with respect to the total thickness of the ink receiving layer. For example, (1) gas phase method of forming a coating layer containing silica, a hydrophilic binder, and a crosslinking agent, and applying a basic solution (second liquid) containing a mordant thereon, (2) gas phase It can be formed by an arbitrary method such as a method in which a coating solution containing silica and a hydrophilic binder and a basic solution containing a mordant (second solution) are applied in multiple layers. The basic solution (second liquid) containing a mordant may contain fine particles, a hydrophilic binder, a crosslinking agent, and the like. By configuring in this manner, since a large amount of mordant is present in a required portion of the ink receiving layer, the color material of the ink-jet ink is mordanted, and the color density, bleeding with time, gloss of the printed part, and characters and images after printing are printed. It is preferable because water resistance and ozone resistance are further improved. A part of the mordant may be contained in a layer provided on the support, and in this case, the mordant applied later may be the same or different.

As the first liquid, a coating liquid for an ink jet recording medium containing gas phase method silica, PVA, a nonionic surfactant according to the present invention, and a boron compound (crosslinking agent) can be prepared, for example, as follows.
A gas phase method silica having a primary particle diameter of 20 nm or less (for example, 10 to 20% by mass) is added to a solution containing the nonionic surfactant according to the present invention (for example, M technique (for example, M Technique ( For example, at a high speed of 10,000 rpm (preferably 5,000 to 20,000 rpm) and dispersed for 20 minutes (preferably 10 to 30 minutes). Then, a boron compound (for example, 0.5 to 20% by mass of silica particles) is added to the dispersion and dispersed under the same conditions as described above, and an aqueous polyvinyl alcohol (PVA) solution (for example, about 1/3 of silica). To achieve a mass PVA), and further dispersion is performed under the same rotation conditions as described above. The obtained coating liquid is a uniform sol with suppressed increase in viscosity, and this is applied to a support by the following coating method to form a layer, thereby forming a porous structure ink receiving layer having a three-dimensional network structure. Is obtained. If necessary, a pH adjuster, a dispersant, a surfactant, an antifoaming agent, an antistatic agent, and the like can be further added to the first liquid.

  In the present invention, the first solution is preferably an acidic solution, and the pH of the coating solution is preferably 5.0 or less, more preferably 4.5 or less, and 4.0 or less. Is more preferable. The pH of the coating solution can be adjusted by appropriately selecting the type and addition amount of the cationic resin. Moreover, you may adjust by adding an organic or inorganic acid. When the pH of the coating solution is 5.0 or less, the crosslinking reaction of the hydrophilic binder by the boron compound in the coating solution can be more sufficiently suppressed.

In addition to the above high-speed rotating wet colloid mill, the dispersing machine used for dispersion is a high-speed rotating disperser, a medium stirring type disperser (ball mill, bead mill, sand mill, etc.), an ultrasonic disperser, a colloid mill disperser, and a high-pressure disperser. However, in order to efficiently disperse the generated fine particles, a medium stirring type disperser, a colloid mill disperser, or a high pressure disperser (homogenizer) is preferable.
As the disperser in the present invention, a medium agitating disperser such as a bead mill is mainly preferably used. From the viewpoint of promoting atomization and high concentration (high Dm), a high-pressure homogenizer (for example, Sugino Co., Ltd.) is used. The same applies to machine-made optimizers).

  Moreover, as a solvent used for preparation of a coating liquid, water, an organic solvent, or these mixed solvents can be used. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, i-propanol and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate and toluene.

  The second liquid (basic solution) is, for example, a mordant (for example, 0.1 to 5.0% by mass) and surfactants (for example, 0.01 to 1.0% by mass in total) in ion-exchanged water. ) And a cross-linking agent (0 to 5.0% by mass) as necessary, and sufficiently stirred. The pH of the second liquid is preferably 7.1 or higher, more preferably 7.5 or higher, and still more preferably 8.0 or higher. If the pH of the basic solution is less than 7.1, the ink receiving layer may be cracked. The pH can be adjusted using ammonia water, sodium hydroxide, calcium hydroxide, amino group-containing compounds (ethylamine, ethanolamine, diethanolamine, polyallylamine, etc.) and the like.

The first liquid can be applied by a known application method such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or a bar coater.
The coating amount of the first liquid, it is common is 50 to 300 g / m ^2, is preferably 100 to 250 g / m ^2.

  The second liquid may be applied before the coating layer after coating comes to show reduced-rate drying. That is, after the application of the ink-receiving layer coating solution, it is preferably produced by introducing a basic solution while the coating layer exhibits constant rate drying. The second liquid may contain a mordant.

  Here, “before the coating layer comes to show reduced drying” usually refers to a process of several minutes immediately after the application of the ink-receiving layer coating solution, and during this period, It shows the phenomenon of “constant rate drying” in which the content of the solvent (dispersion medium) decreases in proportion to time. The time indicating “constant rate drying” is described in, for example, “Chemical Engineering Handbook” (pages 707 to 712, published by Maruzen Co., Ltd., October 25, 1980).

  As described above, after the application of the first liquid, the coating layer is dried until the coating layer exhibits reduced-rate drying. This drying is generally performed at a temperature of 50 to 180 ° C. for 0.5 to 10 minutes (preferably, 0 .5-5 minutes). The drying time naturally varies depending on the coating amount, but usually the above range is appropriate.

  As a method of applying the second liquid before the reduced rate drying is exhibited, (1) a method of further applying the second liquid on the coating layer, (2) a method of spraying by a method such as spraying, (3 ) A method of immersing the support on which the coating layer is formed in the second liquid.

  In the method (1), examples of the application method for applying the second liquid include a curtain flow coater, an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar. A known coating method such as a coater can be used. However, it is preferable to use a method in which the coater does not directly contact the first coating layer that has already been formed, such as an extrusion die coater, a curtain flow coater, or a bar coater.

The coating amount of the second liquid, 5 to 50 g / m ² is generally, 10 to 30 g / m ² is preferred.

  After the application of the second liquid, it is generally heated at a temperature of 40 to 180 ° C. for 0.5 to 30 minutes, and dried and cured. Especially, it is preferable to heat at a temperature of 40 to 150 ° C. for 1 to 20 minutes. For example, when the crosslinking agent contained in the first liquid is borax or boric acid, heating at a temperature of 60 to 100 ° C. is preferably performed for 5 to 20 minutes.

  In addition, when the basic solution (second liquid) is applied at the same time as the ink-receiving layer coating liquid (first liquid) is applied, the first liquid and the second liquid are brought into contact with the support. The ink receiving layer can be formed by simultaneously applying (multilayer application) on the support and then drying and curing.

  Simultaneous coating (multilayer coating) can be performed by a coating method using, for example, an extrusion die coater or a curtain flow coater. After the simultaneous coating, the formed coating layer is dried. In this case, the drying is generally performed by heating the coating layer at a temperature of 40 to 150 ° C. for 0.5 to 10 minutes, preferably at a temperature of 40 It is carried out by heating at -100 ° C for 0.5-5 minutes.

  When simultaneous coating (multilayer coating) is performed using, for example, an extrusion die coater, the two types of coating liquid discharged simultaneously are in the vicinity of the discharge port of the extrusion die coater, that is, before moving onto the support. In that state, it is coated on the support in multiple layers. Since the two-layer coating liquid layered before coating is likely to cause a cross-linking reaction at the interface between the two liquids when transferred to the support, the two liquids to be ejected are mixed in the vicinity of the discharge port of the extrusion die coater. As a result, thickening is likely to occur, which may hinder the application operation. Accordingly, when applying simultaneously as described above, it is preferable to apply the first and second liquids together with a barrier layer liquid (intermediate layer liquid) interposed between the two liquids and simultaneously apply three layers.

  The barrier layer liquid can be selected without particular limitation. For example, an aqueous solution containing a trace amount of water-soluble resin, water, and the like can be given. The water-soluble resin is used in consideration of applicability for the purpose of a thickener and the like. For example, cellulose resin (for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose) And polymers such as polyvinylpyrrolidone and gelatin. Here, the mordant may be contained in the barrier layer solution.

  After the ink receiving layer is formed on the support, the ink receiving layer is subjected to, for example, super calender, gloss calender, etc., and is subjected to calender treatment through the roll nip under heat and pressure, so that surface smoothness, glossiness, It is possible to improve transparency and coating strength. However, the calendering process may cause a decrease in the porosity (that is, the ink absorbability may be decreased), so it is necessary to set the conditions under which the decrease in the porosity is small.

  As roll temperature in the case of performing a calendar process, 30-150 degreeC is preferable and 40-100 degreeC is more preferable. Moreover, as a linear pressure between rolls at the time of a calendar process, 50-400 kg / cm is preferable and 100-200 kg / cm is more preferable.

In the case of inkjet recording, the thickness of the ink receiving layer in the present invention needs to have an absorption capacity sufficient to absorb all of the droplets, and therefore needs to be determined in relation to the porosity in the layer. For example, if the ink amount is 8 nL / mm ² and the porosity is 60%, a film having a layer thickness of about 15 μm or more is required. Considering this point, in the case of ink jet recording, the layer thickness of the ink receiving layer is preferably 10 to 50 μm.

  The pore diameter of the ink receiving layer is preferably 0.005 to 0.030 μm, more preferably 0.01 to 0.025 μm in terms of median diameter. The porosity and pore median diameter can be measured using a mercury porosimeter “Bore Sizer 9320-PC2” manufactured by Shimadzu Corporation.

The ink receiving layer formed in the present invention preferably has a film surface pH of 3 to 6 and more preferably 3 to 5 from the viewpoint of preventing yellowing of the ink receiving layer.
As a method for adjusting the film surface pH of the ink receiving layer, known acids (hydrochloric acid, acetic acid, nitric acid, etc.), bases (NaOH, ammonia, etc.) and salts thereof (ammonium carbonate, etc.) are preliminarily applied to the coating solution. There are a method of adding, a method of sequentially overcoating after forming the ink receiving layer, and the like.
In the present invention, the measurement of the film surface pH of the ink receiving layer is described in J. Org. According to the method for measuring the surface pH of paper defined by TAPPI 49, it can be obtained by measuring after 30 to 40 seconds after dropping 50 μl of pure water having a pH of 6.2 to 7.2 on the ink receiving layer. .

The ink absorbing capacity of the ink-receiving layer (void volume) is preferably from ^{18~40ml / cm 2, 20~30ml / cm} 2 is more preferable.

Further, the ink receiving layer is preferably excellent in transparency, but as a guide, the haze value when the ink receiving layer is formed on a transparent support is preferably 30% or less, More preferably, it is 20% or less.
Here, the haze value is measured using a haze meter “HGM-2DP” manufactured by Suga Test Instruments Co., Ltd.

-Support-
As the support, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to make use of the transparency of the ink receiving layer, it is preferable to use a transparent support or a highly glossy opaque support.
In addition, a read-only optical disk such as a CD-ROM or DVD-ROM, a write-once optical disk such as a CD-R or DVD-R, or a rewritable optical disk is used as a support, and an ink receiving layer is provided on the label surface side. You can also.

As a material that can be used for the transparent support, a material that is transparent and can withstand radiant heat when used in an OHP or a backlight display is preferable. Examples of such materials include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, and the like. Of these, polyesters are preferable, and polyethylene terephthalate is particularly preferable.
Although there is no restriction | limiting in particular as thickness of the said transparent support body, 50-200 micrometers is preferable at the point of the ease of handling.

The highly glossy opaque support preferably has a glossiness of 40% or more on the surface on which the ink receiving layer is provided. The glossiness is a value determined according to the method described in JIS P-8142 (75-degree specular gloss test method for paper and paperboard).
Specifically, the support body shown below is mentioned, for example.

For example, high gloss paper support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, polyesters such as polyethylene terephthalate (PET), nitrocellulose, cellulose acetate, Cellulose esters such as cellulose acetate butyrate, plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by adding a white pigment or the like (surface calendar treatment may be applied). Or a support provided with a polyolefin coating layer containing or not containing a white pigment on the surface of a highly glossy film containing the various paper supports, the transparent support or the white pigment. Can be mentioned.
A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) can also be suitably exemplified. Furthermore, resin-coated paper used for silver salt photographic printing paper is also suitable.

Although there is no restriction | limiting in particular also about the thickness of an opaque support body, 50-300 micrometers is preferable at the point of the ease of handling.
In addition, it is preferable to use a surface of the support that has been subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment or the like in order to improve wettability and adhesion.

Next, a base paper used for a paper support such as resin-coated paper will be described.
As the base paper, wood pulp is used as a main raw material, and paper is made using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp as necessary. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, and LDP with a large amount of short fibers. preferable. However, the ratio of LBSP and / or LDP is preferably 10 to 70% by mass.

As the pulp, chemical pulp (sulfate pulp or sulfite pulp) with few impurities is suitably used, and a pulp having a whiteness improved by performing a bleaching treatment is also useful.
In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols A water retaining agent such as a dispersant, a softening agent such as a quaternary ammonium, and the like can be appropriately added.

  The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is a 24 mesh residual mass% and a 42 mesh residual as defined in JIS P-8207. 30 to 70% of the sum with the mass% of is preferable. In addition, it is preferable that 4 mesh remainder is 20 mass% or less.

The basis weight of the base paper is preferably 30 to 250 g, and particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is 0.7 to 1.2 g / m ² (JI
SP-8118) is common. Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS P-8143.

A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the size that can be added to the base paper can be used.
The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method defined in JIS P-8113.

  The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, etc. can also be used. In addition, an embodiment using a hydrotalcite compound is preferable as the catalyst deactivator of the catalyst of the high density polyethylene, and the content of the catalyst deactivator in the high density polyethylene is based on the amount of the high density polyethylene. 100 to 2,000 ppm is preferable, and 200 to 1,000 ppm is more preferable. As the antioxidant, it is preferable to use only a secondary antioxidant (particularly phosphorus antioxidant), and the content of the secondary antioxidant (particularly phosphorus antioxidant) in the high-density polyethylene is 100 ppm or more and 2,000 ppm or less is preferable with respect to high density polyethylene (HDPE), and 200 ppm or more and 1,000 ppm or less is more preferable.

In particular, the polyethylene layer on the side on which the ink receiving layer is formed is obtained by adding rutile or anatase type titanium oxide, fluorescent whitening agent, ultramarine to polyethylene, as is widely done in photographic paper. Those having improved whiteness and hue are preferred. Here, as a titanium oxide content, about 3-40 mass% is preferable with respect to polyethylene, and 4-30 mass% is more preferable. Although the thickness of a polyethylene layer does not have limitation in particular, 10-50 micrometers is suitable for both front and back layers.
Furthermore, an undercoat layer can be provided on the polyethylene layer in order to provide adhesion to the ink receiving layer. As the undercoat layer, aqueous polyester, gelatin and PVA are preferable. Moreover, as thickness of this undercoat layer, 0.01-5 micrometers is preferable.

  Polyethylene-coated paper can be used as glossy paper, and when polyethylene is melt-extruded onto the base paper surface for coating, a so-called molding process is performed to form a matte or silky surface obtained with ordinary photographic printing paper. Can also be used.

A back coat layer can also be provided on the support. Examples of components that can be added to the backcoat layer include white pigments, aqueous binders, and other components.
Examples of white pigments used in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, Diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigment, styrene Examples thereof include organic pigments such as plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin, and melamine resin.

Examples of the aqueous binder used in the back coat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxy Examples thereof include water-soluble polymers such as methyl cellulose, hydroxyethyl cellulose, and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion.
Examples of other components used in the backcoat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In this example, an inkjet recording sheet is prepared as an example of an inkjet recording medium, and “part” and “%” in the examples are based on mass unless otherwise specified.

Example 1
-Production of support-
50 parts of LBKP made of acacia and 50 parts of LBKP made of aspen were beaten into 300 ml of Canadian freeness by a disc refiner, respectively, to obtain a pulp slurry.
Next, cation-modified starch (CAT0304L, manufactured by NSC Japan) 1.3%, anionic polyacrylamide (DA4104, manufactured by Seiko PMC) 0.15%, alkyl ketene dimer (size) per pulp to the obtained pulp slurry (Pine K, manufactured by Arakawa Chemical Co., Ltd.) 0.29%, epoxidized behenamide 0.29%, and polyamide polyamine epichlorohydrin (Arafix 100, manufactured by Arakawa Chemical Co., Ltd.) 0.32%, and then further antifoaming agent 0.12% was added.

The pulp slurry adjusted as described above is made with a long paper machine and the felt surface of the web is pressed against the drum dryer cylinder via the dryer canvas to dry it. A base paper was obtained by setting to cm and dried, and 1 g / m ² of polyvinyl alcohol (KL-118, manufactured by Kuraray Co., Ltd.) was applied to both sides of the base paper with a size press, followed by calendar treatment. In this way, a base paper having a basis weight of 166 g / m ² and a thickness of 160 μm was made to obtain a base paper.

After performing corona discharge treatment on the wire surface (back surface) side of the obtained base paper, MFR (melt flow rate; hereinafter the same) 16.0 g / 10 min, density 0.96 g / cm ³ using a melt extruder. High density polyethylene [hydrotalcite (trade name: DHT-4A, manufactured by Kyowa Chemical Industry Co., Ltd.) 250 ppm and secondary antioxidant (tris (2,4-di-t-butylphenyl) phosphite (trade name: Irgaphos) 168, Ciba Specialty Chemicals Co., Ltd., 200 ppm)) and MFR 4.0 g / 10 min, low density polyethylene with a density of 0.93 g / cm ^{3 at} a ratio of 75/25 (mass ratio). The blended resin composition was coated to a thickness of 25 g / m ² to form a thermoplastic resin layer having a mat surface (hereinafter, this thermoplastic resin layer surface is referred to as “back side”). Referred to as "face"). After this corona discharge treatment is further applied to the thermoplastic resin layer on the back side, aluminum oxide (“Alumina Zil 100” manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (“Snow manufactured by Nissan Chemical Industries, Ltd.”) are used as antistatic agents. A dispersion in which water was dispersed in water at a mass ratio of 1: 2 was applied so that the dry mass was 0.2 g / m ² .

Then, the corona discharge process was performed to the felt surface (surface) side of the side in which the said thermoplastic resin layer is not provided (back side reverse side). Thereafter, MFR 4.0 g / 10 min, using a melt extruder so that the low-density polyethylene having a density of 0.93 g / m ² to 24 g / m ² was coated with 10 wt% of titanium oxide, made of mirror A thermoplastic resin layer was formed (hereinafter, this mirror side is referred to as “front side”).
As described above, a support in which the surfaces on both sides of the base paper were coated with polyethylene resin was obtained.

-Preparation of coating liquid A (first liquid) for ink receiving layer-
Among the following compositions, first, (1) gas phase method silica fine particles, (2) ion-exchanged water, (3) Charol DC-902P, and (4) ZA-30 are mixed, and manufactured by Jinmaru Enterprises Co., Ltd. After being dispersed using a bead mill KD-P, this dispersion was heated to 45 ° C. and held for 20 hours. Then, (5) boric acid, (6) Himax SC-505E, (7) polyvinyl alcohol solution, (8) Superflex 650 and (9) ethanol water in the following composition were added to this at 30 ° C. A receiving layer coating solution A (first solution) was prepared.

<Composition of coating liquid A for ink receiving layer>
(1) Gas phase method silica fine particles: 100 parts (AEROSIL 300SF75 (primary particle diameter: 7 nm), manufactured by Nippon Aerosil Co., Ltd.)
(2) Ion-exchanged water: 555 parts (3) Charol DC-902P: 5.8 parts (made by Daiichi Kogyo Seiyaku Co., Ltd., 51.5% aqueous solution; dispersant)
(4) ZA-30 ... 5.4 parts (Daiichi Rare Element Chemical Co., Ltd., 50% aqueous solution; zirconyl acetate)
(5) Boric acid (crosslinking agent) aqueous solution (7.5%) ... 50 parts (6) Himax SC-505E ... 4.09 parts (manufactured by Hymo Co., Ltd .; cationic resin 60% aqueous solution)
(7) Polyvinyl alcohol (hydrophilic binder) solution ... 290 parts-Composition of polyvinyl alcohol solution-
Polyvinyl alcohol: 20.3 parts (PVA-235, saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
・ Neugen XL140: 0.85 part (carbon number of lipophilic chain 10, HLB = 15.9, hydrophilic chain = polyoxyalkylene chain, manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; nonionic surfactant according to the present invention )
・ Diethylene glycol monobutyl ether… 6.0 parts (Butizenol 20P, manufactured by Kyowa Hakko Co., Ltd.)
・ Ion-exchanged water: 262.8 parts (8) Superflex 650 (cation-modified polyurethane): 25 parts (Daiichi Kogyo Seiyaku Co., Ltd .; cation-modified latex resin)
(9) Ethanol water (ethanol content 59%) ... 75 parts

-Preparation of inkjet recording sheet-
After the corona discharge treatment was performed on the front surface of the support obtained as described above, a 5-fold diluted aqueous solution of polyaluminum chloride (polyaluminum chloride is used for the first solution that was flowed to a coating amount of 173 ml / m ² . Alfine 83 (manufactured by Daimei Chemical Co., Ltd.) was applied by in-line mixing at a rate of 10.8 ml / m ² , and then applied at 80 ° C. (wind speed 3-8 m / sec) with a hot air dryer. The layer was dried until the solids concentration of the layer reached 20%, during which time the coated layer showed constant rate drying, and before showing reduced rate drying, the basic solution B (second solution) having the following composition was used. It was immersed for 3 seconds to deposit 13 g / m ² on the coating layer, and further dried for 10 minutes at 80 ° C. In this way, an ink jet recording sheet provided with an ink receiving layer having a dry film thickness of 32 μm. Was made.

<Composition of basic solution B>
(1) Boric acid: 0.65 part (2) Ammonium carbonate (first grade: manufactured by Kanto Chemical Co., Ltd.): 4.0 parts (3) Ion exchange water: 89.35 parts (4) Emulgen 109P (10% aqueous solution) ) ... 6 parts (manufactured by Kao Corporation; polyoxyethylene lauryl ether)

(Examples 2 to 4)
An ink jet recording sheet was produced in the same manner as in Example 1 except that Neugen XL140 in “Composition of Polyvinyl Alcohol Solution” was replaced with the surfactant shown in Table 1 below.

(Comparative Examples 1-8)
A comparative inkjet recording sheet was prepared in the same manner as in Example 1 except that Neugen XL140 in “Composition of Polyvinyl Alcohol Solution” was replaced with the surfactant shown in Table 1 below.

(Evaluation)
The following evaluation was performed about the coating liquid A for ink receiving layers and the sheet | seat for inkjet recording which were obtained by the Example and the comparative example. The results of measurement and evaluation are shown in Table 1 below.

-1. Coating liquid viscosity
The ink receiving layer coating liquid A (first liquid) prepared in each Example and Comparative Example was adjusted to 30 ° C., and viscosity (mPa · s) at 30 ° C. using VISCOMETER BL (manufactured by TOKIMEC INC). Was measured.

-2. Black density (K-Dm)-
Each inkjet recording sheet was loaded into an inkjet printer PM G-800 (manufactured by Seiko Epson Corporation), and a black solid image was printed on each of the inkjet recording sheets. Then, the visual density of the solid image was measured using a reflection density meter Xrite 938 (manufactured by Xrite).

-3. Ozone resistance
Using an inkjet printer PM G-800 (manufactured by Seiko Epson Corporation), magenta (M), cyan (C), yellow (Y), and black (K) on each inkjet recording sheet obtained above. ) Were printed and stored for 96 hours in an environment with an ozone concentration of 10 ppm. The density of magenta (M), cyan (C), yellow (Y), and black (K) before and after storage was measured using a reflection densitometer (Xrite 938) manufactured by Xrite, and the residual density ratio of each color. Was calculated.

  As shown in Table 1, in contrast to the comparative example in which the thickening of the coating liquid could not be suppressed, in the example, the thickening of the coating liquid for inkjet recording medium for forming the ink receiving layer was effectively suppressed. The image recorded on the ink receiving layer formed using this was high in image density and good in ozone resistance.

Claims (7)

A coating liquid for an inkjet recording medium used for forming an ink receiving layer of an inkjet recording medium that receives ink and records an image,
At least gas phase method silica having a primary particle diameter of 20 nm or less, a hydrophilic binder, a lipophilic chain having 13 or less carbon atoms including a branched structure, a polyoxyalkylene chain as a hydrophilic chain, and HLB A nonionic surfactant that is 14.0 or more and a water-soluble polyvalent metal salt,
The content of the nonionic surfactant is 0.2% by mass or more and 5% by mass or less with respect to the mass of the vapor phase silica.
A coating solution for an inkjet recording medium, wherein the content of the water-soluble polyvalent metal salt is 0.1% by mass or more and 20% by mass or less with respect to the mass of the vapor phase silica.   2. The ink jet recording medium coating solution according to claim 1, wherein the water-soluble polyvalent metal salt is zirconyl acetate. Jet recording medium coating solution according to claim 1 or 2, characterized in that further comprises a polymer having a poly diallyl dimethyl ammonium chloride structure. The coating liquid for an inkjet recording medium according to any one of claims 1 to 3 , wherein the hydrophilic binder is polyvinyl alcohol having a saponification degree of 90% or less. The coating liquid for an inkjet recording medium according to any one of claims 1 to 4 , further comprising a cation-modified latex resin. In an inkjet recording medium having an ink receiving layer on a support,
The ink receiving layer has at least gas phase method silica having a primary particle diameter of 20 nm or less, a hydrophilic binder, and a lipophilic chain having 13 or less carbon atoms including a branched structure, and a polyoxyalkylene chain as a hydrophilic chain A nonionic surfactant having an HLB of 14.0 or more, and a water-soluble polyvalent metal salt,
The content of the nonionic surfactant is 0.2% by mass or more and 5% by mass or less with respect to the mass of the vapor phase silica.
An ink jet recording medium in which the content of the water-soluble polyvalent metal salt is 0.1% by mass or more and 20% by mass or less based on the mass of the vapor phase silica. The inkjet recording medium according to claim 6 , wherein the water-soluble polyvalent metal salt is zirconyl acetate.