JP2006218719A - Inkjet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording paper, which has high lustrous properties, through the suppression of development of bronzing due to the cohesion of coloring matter in a dye ink, and in which a high print density and a high gloss are obtained even in the print using pigment ink. <P>SOLUTION: This inkjet recording paper comprises a void-type ink absorbing layer including fine inorganic particles having at least an average particle diameter of not more than 100 nm and a hydrophilic polymer on a support, wherein the ink absorbing layer includes a Pluronic type nonionic surface active agent and a cationic surface active agent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel inkjet recording paper.

  Inkjet recording methods for recording with water-based ink are well known, and in recent years, the image quality of inkjet recording has been rapidly improved. In particular, with the recent increase in image quality and speed, high ink absorptivity is required for the ink receiving layer. The ink receiving layer is generally formed mainly from a hydrophilic binder, and includes a swelling type that retains ink by the swelling action of the hydrophilic binder, and a void type that forms a porous film with inorganic fine particles and a small amount of a hydrophilic binder. The latter void-type ink receiving layer is preferable from the viewpoint of high ink absorbability.

  In inkjet recording, a water-soluble dye is usually used as a coloring material. However, since this water-soluble dye is highly hydrophilic, it can be stored for a long time under high humidity after ink-jet recording, or water droplets adhere to the recording surface. In this case, the pigment tends to bleed. In order to solve this problem, a dye mordant is generally added to the ink receiving layer as a substance having a dye fixing ability, and the surface having such a dye fixing ability is a surface. Examples thereof include cationic inorganic fine particles (for example, alumina fine particles), cationic polymers having a primary to tertiary amino group or a quaternary ammonium base in the molecule, and the like.

  Among them, the cationic polymer is preferably used because it has a relatively high dye fixing ability. Examples of the dye mordant include polyalkylene polyamine dicyandiamide condensates described in JP-B-2-3567 and JP-A-9-254529. As the dye mordant has higher dye fixing ability, the dye is mordanted on the surface of the ink absorption layer, resulting in higher print density and improved water resistance and image bleeding due to storage after inkjet recording. An optimal dye mordant for the type of dye included is selected.

  In addition, in some cases, polyvalent metal ions are used in combination in order to enhance the fixing property of the dye by the cationic polymer. For example, as disclosed in JP-A-60-67190 and JP-A-61-1484 A method is described.

  However, when trying to fix the dye strongly, there is often a problem that the dye is precipitated. The ease of such dye aggregation depends on the type of cationic polymer, the type of dye, and the combination of both, but even if there is no problem immediately after printing, the dye aggregation proceeds gradually during storage for a long time. It can happen.

  When the dye is deposited, the print surface becomes metallic like an image (hereinafter, this phenomenon is referred to as bronzing), or the image becomes non-glossy. The former tends to occur mainly when the dye has high crystallinity, and the latter tends to occur when the dye is less likely to be crystallized. In either case, the print quality is greatly reduced. End up.

  This problem is particularly likely to occur particularly in ink jet recording paper having a void type ink receiving layer. The reason for this is not clear, but when the void-type ink receiving layer is filled with ink, the hydrophilic binder hardly exists in the void portion, so that the movement of the dye fixing agent such as a cationic polymer is relatively easy to occur. It is presumed that this is because the dye is easily aggregated by diffusing to the surface of the ink receiving layer.

  This problem is more likely to be promoted when inorganic cation ions are present in the ink receiving layer, and particularly polyvalent metal compounds (for example, magnesium, calcium, aluminum, zirconium compounds, etc.) that are effective in print density, water resistance and bleeding prevention. ) Presents a problem that facilitates aggregation of the dye. Further, it is known that an ink jet recording paper having a high glossiness can be produced by applying a void-type ink receiving layer to a non-water-absorbing support such as a polyethylene-coated paper whose both surfaces are coated with polyethylene. . However, the inventors have found that there is a problem that bronzing easily occurs when such a non-water-absorbing support is used. Since the non-water-absorbing support has no ink absorption capability, it is necessary to hold the ink only by the ink absorption layer, and as a result of the ink filling the gap layer for a relatively long time, the transfer of the dye fixing agent is estimated as described above. It is thought that the dye aggregation based on this is likely to occur.

On the other hand, a method in which two kinds of surfactants are used in combination in the ink absorbing layer has been proposed.
For example, an inkjet recording sheet is disclosed in which an ink receiving layer containing a cationic fluorosurfactant and a nonionic fluorosurfactant together with a polyvinyl acetal resin is provided (see, for example, Patent Document 1). According to this method, it is said that an ink jet recording sheet having high transparency, ink receptivity, water resistance, sharpness of recorded image, and excellent durability of the ink receiving layer can be obtained. Is intended to be a swellable type, and is completely different from the void-type inkjet recording paper targeted by the present invention. In addition, an ink jet recording sheet is proposed in which a colorant receiving layer contains two or more kinds of surfactants, and the surfactants are co-dissolved (for example, Patent Document 2). reference.). According to this method, it is said that an ink jet recording sheet having a good appearance (planar state) is obtained without causing a repelling failure. However, in Patent Document 2, the pluronic nonionic surface activity defined in the present invention is used. There is no specific description of using a combination of a colorant and a cationic surfactant. Moreover, the present invention has a high print density and gloss intended for the present invention, and does not deteriorate bronzing due to dye precipitation during ink jet recording. There is no mention or suggestion on how to obtain
JP-A-8-104055 (Claims) JP 2004-50529 A (Claims)

  The present invention has been made in view of the above-mentioned problems, and its purpose is to have high gloss, to suppress the occurrence of bronzing due to aggregation of pigments in dye ink, and to obtain a high print density and gloss. An object of the present invention is to provide an ink jet recording paper that can obtain a high print density even in printing using pigment ink.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
On the support, there is a void-type ink absorbing layer containing at least inorganic fine particles having an average particle size of 100 nm or less and a hydrophilic polymer, and the ink absorbing layer comprises a pluronic-type nonionic surfactant and a cationic surfactant. An ink jet recording paper comprising:

(Claim 2)
2. The 0.3% by mass aqueous solution (35 ° C.) of the pluronic-type nonionic surfactant has a dynamic surface tension of 60 mN / m or less at 20 milliseconds as measured by a maximum bubble pressure method. The inkjet recording paper as described.

(Claim 3)
The inkjet recording paper according to claim 1 or 2, wherein the cationic surfactant is a compound having a quaternary ammonium salt in the molecule.

(Claim 4)
4. The ink jet recording paper according to claim 3, wherein the compound having a quaternary ammonium salt in the molecule is lauryltrimethylammonium chloride.

(Claim 5)
The mass ratio C / N of the cationic surfactant (C) and the pluronic nonionic surfactant (N) in the ink absorption layer is 0.05 or more and 0.50 or less. The inkjet recording paper of any one of -4.

(Claim 6)
The inkjet recording paper according to claim 1, wherein the ink absorption layer contains a polyvalent metal compound.

(Claim 7)
The inkjet recording paper according to any one of claims 1 to 6, wherein the support is a non-water-absorbing support.

  According to the present invention, an ink jet that has high glossiness, suppresses the occurrence of bronzing due to aggregation of pigments in dye ink, and provides high print density and gloss, and also provides high print density in pigment ink printing. Recording paper can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor has a void-type ink absorbing layer containing at least inorganic fine particles having an average particle diameter of 100 nm or less and a hydrophilic polymer on the support, Ink jet recording paper characterized in that the ink absorbing layer contains a pluronic-type nonionic surfactant and a cationic surfactant allows high print density without causing deterioration in print quality due to bronzing due to dye aggregation. As soon as the present invention has been realized, it has been found that an ink jet recording paper capable of obtaining gloss can be realized.

  That is, with respect to the suppression of bronzing, which is an object of the present invention, by containing a pluronic nonionic surfactant in a void-type ink absorbing layer having inorganic fine particles having an average particle size of 100 nm or less and a hydrophilic polymer. It has been found that there is a bronzing suppression effect. However, it has been found that when a pluronic nonionic surfactant is contained, there is a problem that the print density is lowered.

  As a result of studying this issue, the ink jet ink layer containing a pluronic-type nonionic surfactant and the ink jet recording paper further containing a cationic surfactant have no decrease in print density and gloss and suppress bronzing. I found out that it would be possible. As a result of further detailed investigation, by selecting a pluronic-type nonionic surfactant and a cationic surfactant, the density of the printed image is improved even when pigment ink is used in addition to the solution of the above problems. I found.

  Although it has not yet been clearly interpreted that the inclusion of the pluronic nonionic surfactant and the cationic surfactant can improve the bronzing without deterioration of print density and gloss, the following is considered. Generally, since a nonionic surfactant has a cloud point, the solubility of the nonionic surfactant is lowered when the ink absorbing layer is applied and then dried at a high temperature, and the transparency and gloss of the ink absorbing layer are deteriorated. As a result, it is estimated that the optical density of the dye decreases due to light scattering. Although this property is also possessed by pluronic type nonionic surfactants, the combined use of cationic surfactants improves the solubility of pluronic type nonionic surfactants and prevents precipitation. It is thought that there is no deterioration and bronzing is suppressed.

  The effect of improving the density of a printed image using pigment ink by using a cationic surfactant and a pluronic nonionic surfactant is estimated as follows.

  When recording with a pigment-based ink, the pigment particles usually have a size of about 0.1 to 0.5 μm. If the recording paper does not have a pore diameter equal to or larger than this particle size, the pigment ink is not contained in the ink receiving layer. It is not accommodated and is fixed in an aggregated state on the surface of the ink receiving layer. The unevenness formed by the pigment particles causes light scattering in the visible region of a short wavelength, and thus particularly affects the print density of yellow. After the pigment ink has landed on the recording paper, the pluronic nonionic surfactant diffuses from the recording paper into the ink and lowers the surface energy of the ink droplets. As a result, the unevenness formed by the pigment ink is leveled (smoothed). It is believed that scattering is suppressed and print density increases. Although it is not clear that the effect varies depending on the type of surfactant, it is presumed that the diffusion rate in the recording paper varies depending on the structure of the surfactant.

  In addition, by selecting a compound having a dynamic surface tension of 20 msec or less measured by the maximum bubble pressure method for a 0.3% aqueous solution of a pluronic-type nonionic surfactant, the gloss of the pigment ink print portion is selected. It was also found that the sex was improved. Regarding this result, it is considered that the ink droplets are easy to level because the surfactant diffuses into the pigment ink faster when the ink lands.

  Hereinafter, the details of the inkjet recording paper of the present invention will be described.

  The inkjet recording paper of the present invention (hereinafter also simply referred to as recording paper) has a void-type ink absorbing layer containing at least inorganic fine particles having an average particle diameter of 100 nm or less and a hydrophilic polymer on a support, The ink absorbing layer contains a pluronic nonionic surfactant and a cationic surfactant.

  First, the pluronic nonionic surfactant according to the present invention will be described.

  The pluronic-type nonionic surfactant according to the present invention is a compound represented by the following general formula (1) or (2), and these compounds are commercially available from, for example, Takemoto Yushi Co., Ltd., Asahi Denka Co., Ltd. Has been.

General formula (1)
HO- (EO) _a- (AO) _b- (EO) _c -H
General formula (2)
HO- (AO) _d- (EO) _e- (AO) _f- H
In the general formulas (1) and (2), EO represents an oxyethylene group, and AO represents an oxyalkylene group having 3 or more carbon atoms. Examples of the oxyalkylene group having 3 or more carbon atoms include an oxypropylene group, an oxybutylene group, and an oxy long chain alkylene group, and the oxypropylene group is most preferable.

  a, b, c, d, e, and f each represent a number of 1 or more. (A + c) / (a + b + c) is preferably 0.5 or less, and more preferably 0.3 or less. Furthermore, (e) / (d + e + f) is preferably 0.5 or less, and more preferably 0.3 or less.

  In the pluronic-type nonionic surfactant represented by the general formula (1) or (2), the average molecular weight composed of an ethylene oxide chain and an alkylene oxide chain is preferably 500 to 10,000, more preferably 1,000. ~ 5,000.

  In the copolymer according to the present invention, the ratio of ethylene oxide in the copolymer is preferably 40% by mass or less of the total mass of the copolymer from the viewpoint of image quality improvement, which is an object effect of the present invention, and in particular. Preferably it is 5-30 mass%.

  Moreover, it is preferable that content of the pluronic type nonionic surfactant which concerns on this invention is 0.5-10 mass% with respect to the total mass of an inorganic fine particle. If the content is 0.5% by mass or more, the objective effect of the present invention can be sufficiently exerted, and if the content is 10% by mass or less, mottled printing unevenness can be suppressed.

  The pluronic-type nonionic surfactant according to the present invention can be obtained according to a synthesis method known in the art. For example, the pluronic-type nonionic surfactant represented by the general formula (1) is composed of polypropylene glycol and ethylene oxide. Can be synthesized by addition polymerization under alkaline conditions. The pluronic nonionic surfactant represented by the general formula (2) can be synthesized by addition polymerization of polyethylene glycol with propylene glycol under alkaline conditions. The average molecular weight and the ratio of ethylene oxide in the molecule can be adjusted to desired conditions by the molecular weight of polypropylene glycol or polyethylene glycol and the added mass of ethylene oxide or propylene oxide.

  The pluronic nonionic surfactant according to the present invention is not particularly limited, but the dynamic surface tension measured at 35 ° C. measured by a maximum bubble pressure method of a 0.3% aqueous solution is preferably 60 mN / m or less at 20 msec. It is preferable to use a pluronic type nonionic surfactant that is more preferable from the viewpoint that the object and effects of the present invention can be further exhibited, and more preferably 30 mN / m or more and 60 mN / m or less.

  The maximum bubble pressure method (Maximum Bubble Pressure Method) referred to in the present invention is a means for generating bubbles in a liquid and measuring the surface tension based on the pressure applied to the bubbles. Measurement of surface tension is possible. Also called the bubble pressure method.

  Specifically, nitrogen gas is blown out from a thin tube inserted into the liquid to expand the bubble, thereby expanding the interface between the liquid and the gas, and obtaining the surface tension from the maximum pressure at that time.

When the radius of the spherical bubble is increased from R to R + dR, the increase ΔA in the surface area of the bubble is
ΔA = 4π (R + dR) 2-4πR2 = 8πR · dR
It is represented by

On the other hand, at this time, the work performed by the pressure is to move the spherical surface of 4πR2 by dR.
W = ΔP · 4πR2dRW = ΔP · 4πR2dR
It is represented by

Therefore, the surface tension γ is
γ = W / ΔA (Definition of surface tension)
= ΔP · R / 2
It is also a method to ask for.

  Specific examples of the interfacial tension measuring device based on the maximum bubble pressure method include the Dynamic Surface Tension Meter BP-D4 type manufactured by Kyowa Interface Science Co., Ltd.

  The pluronic-type nonionic surfactant exhibiting dynamic surface tension according to the present invention has a high ability to reduce dynamic surface tension among general surfactants, and the above-described general formula (1) or (2) Is a compound corresponding to the above definition.

  Next, the cationic surfactant will be described.

  Cationic surfactants that can be used in the present invention are broadly classified into two types, amine salt types and quaternary ammonium salt types. For example, “Introduction to New Surfactants” (published by Sanyo Chemical Industries, Ltd.) Specific structural examples are described on pages 63-81.

  Specifically, examples of the amine salt type include polyoxyethylene alkylamine, N-alkylpropyleneamine, N-alkylpolyethylenepolyamine, N-alkylpolyethylenepolyamine dimethyl sulfate, alkylpiguanide, long chain amine oxide, Examples include alkyl imidazoline, 1-hydroxyethyl-2-alkyl imidazoline, 1-acetylaminoethyl-2-alkyl imidazoline, 2-alkyl-4-methyl-4-hydroxymethyl oxazoline.

  Examples of quaternary ammonium salt types include long-chain primary amine salts, alkyltrimethylammonium salts, dialkyldimethylethylammonium salts, alkyldimethylammonium salts, alkyldimethylbenzylammonium salts, alkylpyridinium salts, and alkylquinolinium salts. , Alkylisoquinolinium salt, alkylpyridinium sulfate, stearamide methylpyridinium salt, acylaminoethyl diethylamine salt, acylaminoethylmethyldiethylammonium salt, alkylamidopropyldimethylbenzylammonium salt, fatty acid polyethylene polyamide, acylaminoethylpyridinium salt , Acylcoraminoformylmethylpyridinium salt, stearoxymethylpyridinium salt, fatty acid triethanolamine, fatty acid trieta Ruamingi salt, trioxyethylene fatty acid triethanolamine, fatty acid dibutylaminoethanol, cetyl oxymethyl pyridinium salt, a p- isooctyl phenoxyethoxyethyl dimethyl benzyl ammonium salts and the like.

  The cationic surfactant used in the ink absorbing layer according to the present invention is not particularly limited, but is preferably a quaternary ammonium salt type cationic surfactant, and lauryltrimethylammonium chloride is particularly preferable.

  Although the usage-amount of the cationic surfactant based on this invention is not specifically limited, Mass ratio C / N of a cationic surfactant (C) and the said pluronic type nonionic surfactant (N) is 0.05. It is preferable to add so that it may become the range below 0.5 or more. If C / N is within this range, it is easy to achieve better print density, bronzing suppression and high gloss.

  In the present invention, as a method for measuring the content of the pluronic-type nonionic surfactant or cationic surfactant in the ink absorbing layer, a known surfactant quantification method can be applied, and “new surfactant” (Measured by Hiroshi Horiguchi, Sankyo Publishing Co., Ltd.) Chapter-14 “Analysis of Surfactant” can be measured according to the method described above. The blue method and the HPLC method for detecting electrical conductivity can be applied, and the nonionic surfactant can be quantified by a cobalt thiocyanate method, an alumina column method, or the like.

  Next, other components of the inkjet recording paper of the present invention will be described.

  The ink absorbing layer according to the present invention contains inorganic fine particles having an average particle size of 100 nm or less and a hydrophilic binder in addition to the above-mentioned surfactants, and constitutes voids.

  Examples of inorganic fine particles that can be used in the present invention include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, and zinc sulfide. , Zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. Mention may be made of white inorganic pigments. The inorganic fine particles can be used as primary particles or in a state where secondary agglomerated particles are formed.

  In the present invention, from the viewpoint of obtaining a high-quality print on an inkjet recording paper, silica-based particles or alumina is used from the viewpoint that inorganic fine particles having a low refractive index and an average particle size of 100 nm or less can be obtained relatively inexpensively. Diameter particles are preferable, and alumina, pseudoboehmite, colloidal silica, fine particle silica synthesized by a gas phase method, and the like are preferable. Particularly, fine particle silica synthesized by a gas phase method with an average particle size of 100 nm or less is particularly preferable. .

  The silica synthesized by this vapor phase method may have a surface modified with aluminum. The aluminum content of vapor-phase process silica whose surface is modified with aluminum is preferably 0.05 to 5% by mass with respect to silica.

  The particle diameter of the inorganic fine particles is 100 nm or less from the viewpoint of glossiness and color density, and the lower limit of the particle diameter is not particularly limited, but is preferably approximately 10 nm or more from the viewpoint of production of the inorganic fine particles.

  The average particle size of the inorganic fine particles is obtained as a simple average value (number average) by observing the cross section and surface of the porous ink absorption layer with an electron microscope and determining the particle size of 100 arbitrary particles. Here, each particle size is expressed by a diameter assuming a circle equal to the projected area.

  The inorganic fine particles may remain as primary particles or may be present in the porous film as secondary particles or higher-order agglomerated particles, but the average particle diameter is determined by an ink absorption layer when observed with an electron microscope. Among them, the particle size of the particles forming independent particles.

  When the inorganic fine particles are secondary or higher aggregated particles, the average primary particle size is equal to or less than the average particle size observed in the porous film, and the primary particle size of the inorganic fine particles is 30 nm or less. Are more preferable, and fine particles of 4 to 20 nm are more preferable.

The content of the inorganic fine particles in the water-soluble coating solution is 5 to 40% by mass, and particularly preferably 7 to 30% by mass. The inorganic fine particles need to form an ink-absorbing layer having sufficient ink absorptivity and less cracking of the film, and the amount of 5 to 50 g / m ² is preferable in the ink-receiving layer. . Furthermore, it is especially preferable that it is 10-30 g / m < ² >.

  The hydrophilic binder contained in the ink absorbing layer is not particularly limited, and conventionally known hydrophilic binders can be used. For example, gelatin, polyvinyl pyrrolidone, polyethylene oxide, polyacrylamide, polyvinyl alcohol and the like can be used. However, polyvinyl alcohol is particularly preferable from the viewpoint of relatively small moisture absorption characteristics of the binder and less curling of the recording paper and from the viewpoint of high binder capacity of inorganic fine particles and excellent cracking and film-forming properties when used in a small amount.

  As polyvinyl alcohol preferably used in the present invention, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol such as polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. Alcohol is also included.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 300 or more, particularly preferably an average degree of polymerization of 1,000 to 5,000, and a saponification degree of 70. ~ 100% is preferable, and 80 ~ 99.8% is particularly preferable.

  Examples of the cation-modified polyvinyl alcohol include polyvinyl having a primary to tertiary amino group or a quaternary amino group in the main chain or side chain of the polyvinyl alcohol as described in JP-A No. 61-10383. These are alcohols, which are obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

  Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride. N-vinylimidazole, N-methylvinylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxyethyltrimethylammonium chloride, trimethyl- (3-methacrylamidopropyl) ammonium chloride, and the like.

  The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

  Examples of the anion-modified polyvinyl alcohol include polyvinyl alcohol having an anionic group described in JP-A-1-206088, vinyl alcohol described in JP-A-61-237681 and JP-A-63-330779, and water-soluble. And a copolymer with a vinyl compound having a functional group, and a modified polyvinyl alcohol having a water-soluble group described in JP-A-7-285265.

  Nonionic modified polyvinyl alcohol is, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group described in JP-A-7-9758 to a part of vinyl alcohol, and described in JP-A-8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol.

  Polyvinyl alcohol can be used in combination of two or more, such as the degree of polymerization and the type of modification. In particular, when using polyvinyl alcohol having a degree of polymerization of 2,000 or more, the degree of polymerization is from 0.05 to 10% by weight, preferably 0.1 to 5% by weight, based on the inorganic fine particles. Addition of 2,000 or more polyvinyl alcohol is preferred because there is no significant thickening.

  Moreover, it is preferable to use a polymer compound that is crosslinked or polymerized by ionizing radiation as the hydrophilic binder of the ink absorbing layer according to the present invention. The high molecular compound that is crosslinked or polymerized by ionizing radiation is a water-soluble resin that undergoes a reaction to undergo crosslinking or polymerization by irradiation with ionizing radiation such as ultraviolet rays and electron beams, and is water-soluble before the reaction. However, it is a resin that becomes substantially water-insoluble after the reaction. The resin has hydrophilicity after the reaction and maintains sufficient affinity with ink.

  Such resins include saponified polyvinyl acetate, polyvinyl acetal, polyethylene oxide, polyalkylene oxide, polyvinyl pyrrolidone, polyacrylamide, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, or derivatives of the hydrophilic resins, and It is at least one selected from the group consisting of copolymers, or a hydrophilic resin modified with a modifying group such as a photodimerization type, a photodecomposition type, a photopolymerization type, a photomodification type, or a photodepolymerization type It is. Among them, a resin modified with a photodimerization type or a photopolymerization type modification group is preferable from the viewpoint of sensitivity or stability of the resin itself. As the photodimerization-type modifying group, those having a diazo group, a cinnamoyl group, a styrylpyridinium group, or a stilquinolium group introduced are preferable, and a resin that is dyed with a water-soluble dye such as an anionic dye after photodimerization is preferable. Examples of such resins include resins having a cationic period such as primary amino group or quaternary ammonium group, such as JP-A-62-283339, JP-A-1-198615, JP-A-60-252341. No., JP-A 56-67309, JP-A 60-129742, etc., photosensitive resins (compositions), and after curing, become cationic after curing such as an azide group that becomes an amino group Examples of the resin include photosensitive resins (compositions) described in JP-A-56-67309.

  Specific examples include the following compounds, but the present invention is not limited only to these compounds.

  The photosensitive resin described in JP-A-56-67309 contains the following formula (I) in a polyvinyl alcohol structure.

2-azido-5-nitrophenylcarbonyloxyethylene structure represented by the following formula (II)

It is a resin composition which has 4-azido-3-nitrophenyl carbonyloxyethylene structure represented by these.

  Specific examples of the photosensitive resin are described in Examples 1 and 2 in the official gazette, and the constituent components and usage ratio of the photosensitive resin are described on page 2 of the official gazette.

  JP-A-60-129742 discloses the following formulas (III) and (IV) in a polyvinyl alcohol structure as a photosensitive resin.

The resin composition which has the following structure is mentioned.

  In the present invention, among the hydrophilic resins that are cross-linked by ionizing radiation, examples of the photopolymerizable modifying group include a structural unit represented by the following general formula (A) disclosed in JP-A No. 2000-181062. Polyvinyl acetate saponified product having the above is preferable from the viewpoint of reactivity.

In the general formula (A), R ₁ represents a hydrogen atom or a methyl group, Y represents an aromatic ring or a simple bond, and X represents — (CH ₂ ) _m —COO—, —O—CH ₂ —. COO- or -O- is represented, m is an integer of 0-6, n represents 1 or 2.

  In the present invention, it is preferable to add a photoinitiator or a sensitizer together with a hydrophilic binder containing a polymer compound polymerized by ionizing radiation. These compounds may be chemically bonded to a hydrophilic binder containing the above polymer compound in a state of being dissolved or dispersed in a solvent.

  The photoinitiator and photosensitizer to be applied are not particularly limited, and conventionally known photoinitiators or photosensitizers can be used. For example, benzophenones (for example, benzophenone, hydroxybenzophenone, bis- N, N-dimethylaminobenzophenone, bis-N, N-diethylaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, etc.), thioxanthones (eg, thixatone, 2,4-diethylthioxanthone, isopropylthioxanthone, chlorothioxanthone, Isopropoxychlorothioxanthone), anthraquinones (eg, ethyl anthraquinone, benzanthraquinone, aminoanthraquinone, chloroanthraquinone, etc.), acetophenones, benzoin ethers (eg, benzoin) Tilether, etc.), 2,4,6-trihalomethyltriazines, 1-hydroxycyclohexyl phenyl ketone, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4, 5-di (m-methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-phenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-phenylimidazole dimer , 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, 2, -di (p-methoxyphenyl) -5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) 2,4,5-diphenylimidazole dimer 2,4,5-triarylimidazole dimer, benzyldimethyl ketal, 2- N-di-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-hydroxy-2 -Methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, phenanthrenequinone, 9,10 -Benzoins such as phenanthrenequinone, methylbenzoin, ethylbenzoin, acridine derivatives (for example, 9-phenylacridine, 1,7-bis (9,9'-acridinyl) heptane, etc.), bisacylphosphine oxide and the like The above-mentioned compounds may be used alone or in combination of two or more.

  In particular, water-soluble 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 4- (2-hydroxyethoxy) -phenyl- (2- Water-soluble initiators such as hydroxy-2-propyl) ketone, thioxanthone ammonium salt, and benzophenone ammonium salt are preferable from the viewpoint of crosslink efficiency because of excellent mixing properties.

  In addition to these initiators, accelerators and the like can also be added. Examples of these include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethanolamine, diethanolamine, triethanolamine and the like.

  In such a resin, the polymerization degree of the mother polyvinyl alcohol resin is preferably 300 or more, and more preferably 1700 or more. The modification rate of the ionizing radiation reaction-modifying group with respect to the segment is preferably 4 mol% or less, more preferably 1 mol% or less. If the polymerization degree of the segment is 300 or less or the modification rate exceeds 4 mol%, the crosslinking density of the coating film is too high, and the breakability of the dried coating film is remarkably deteriorated. At the same time, if the crosslinking density is too high, the balance between hygroscopicity and dimensional stability with the substrate is poor, and curling resistance is deteriorated.

  In the method for producing an inkjet recording paper of the present invention, when a polymer compound is used as the hydrophilic binder by the ionizing radiation, a coating liquid containing the polymer compound is applied by the ionizing radiation, and the total solid content of the coating layer is obtained. The coating layer is gelled by irradiating ionizing radiation at a concentration of 5 to 90%, and then dried. Examples of the ionizing radiation in the present invention include electron beams, ultraviolet rays, α rays, β rays, γ rays, and X-rays. In view of the widespread use of electron beam, ultraviolet rays or ultraviolet rays are preferable.

  Examples of the electron beam irradiation method include a scanning method, a curtain beam method, and a broad beam method. The curtain beam method is preferable from the viewpoint of processing capability. The acceleration voltage of the electron beam can be changed as appropriate depending on the specific gravity and film pressure of the coating film, but 20 kV to 300 kV is appropriate. The irradiation amount of the electron beam is preferably in the range of 0.1 to 20 Mrad.

  As the ultraviolet light source, for example, low pressure, medium pressure, high pressure mercury lamp, metal halide lamp and the like having an operating pressure of 100 Pa to 1 MPa are used. From the viewpoint of wavelength distribution of the light source, a high pressure mercury lamp and a metal halide lamp are preferable, and a metal halide lamp is more preferable. preferable.

In particular, when the wavelength of the light source includes ultraviolet rays of 300 nm or less, or when the irradiation energy exceeds 100 J / cm ² , the core of the ionizing radiation crosslinkable resin or various coexisting additives are decomposed by ionizing radiation. In addition to not being able to obtain the effects of the present invention, there is a possibility that problems such as odor derived from the decomposition products may occur. On the contrary, when the irradiation energy is less than 0.1 mJ / cm ² , the crosslinking efficiency is insufficient and the effect of the present invention cannot be sufficiently obtained. Therefore, it is preferable to provide a filter that cuts light having a wavelength of 300 nm or less as the light source, and the output of the lamp is preferably 400 W to 30 kW and the illuminance is preferably 10 mW / cm ^{2 to} 10 kW / cm ² . Preferably as the radiation energy is 0.1mJ / cm ² ~100mJ / cm ² in the present invention, more preferably ^{1mJ / cm 2 ~50mJ / cm 2} .

When giving the same integrated light quantity (mJ / cm ² ), the preferable range of illuminance is due to the change in the light transmittance. When the concentration distribution of the generated cross-linking reactive species is different due to the transmittance of ultraviolet rays, and the ultraviolet illuminance is high, a high concentration of cross-linking reactive species is generated on the surface layer, and a hard and dense film is formed on the surface of the coating film. When the illuminance is in a preferable range, the degree of cross-linking of the surface layer is low and light permeability in the deep direction is high, so that gentle cross-linking is uniformly formed in the deep direction. If the illuminance is too low, it takes a long time to give the necessary integrated illuminance, which is not only disadvantageous in terms of equipment introduction, but also because the amount of absolute light due to scattering of ultraviolet rays by the coating film is insufficient. Absent.

  The ratio of the inorganic fine particles to the hydrophilic binder in the ink absorbing layer is preferably 2 to 20 by mass ratio. If the mass ratio is 2 times or more, a porous film having a sufficient porosity can be obtained, it becomes easy to obtain a sufficient void volume, and does not cause a situation where the voids are blocked by swelling during ink jet recording with a hydrophilic binder that can be maintained. As a result, a high ink absorption speed can be maintained. On the other hand, if this ratio is 20 times or less, cracks are less likely to occur when the ink absorbing layer is applied as a thick film. The ratio of the inorganic fine particles to the particularly preferred hydrophilic binder is 2.5 to 12 times, most preferably 3 to 10 times.

  Various additives can be added to the water-soluble coating liquid for forming the ink absorbing layer or other constituent layers according to the present invention. Examples of such additives include cationic mordants, polyvalent metal compounds, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or these Copolymers, organic latex fine particles such as urea resin or melamine resin, anionic, cationic, nonionic and amphoteric surfactants, JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476 Described in JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61465991, JP-A-1-95091 and JP-A-3-13376. Anti-fading agents, JP-A-59-42993, 59-52689, 62-2 No. 0069, JP-A-61-228771 and JP-A-4-219266, etc., pH brighteners such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate, Various known additives such as antifoaming agents, preservatives, thickeners, antistatic agents and matting agents can also be contained.

  As the cationic mordant, a polymer mordant having a primary to tertiary amino group and a quaternary ammonium base is used, but there is little discoloration or deterioration of light resistance during long-term storage, and the mordant ability of the dye is sufficiently high. Therefore, a polymer mordant having a quaternary ammonium base is preferable. A preferred polymer mordant is obtained as a homopolymer of a monomer having the quaternary ammonium base, a copolymer with another monomer, or a condensation polymer.

  In the ink jet recording paper of the present invention, it is particularly preferable that the ink absorbing layer contains a polyvalent metal compound.

  Examples of the polyvalent metal compound according to the present invention include metal compounds such as aluminum, calcium, magnesium, zinc, iron, strontium, barium, nickel, copper, scandium, gallium, indium, titanium, zirconium, tin, and lead. The polyvalent metal compound may be a polyvalent metal salt. Among them, the compound composed of magnesium, aluminum, zirconium, calcium, and zinc is preferable because it is colorless, the polyvalent metal compound is more preferably a compound containing a zirconium atom, an aluminum atom, or a magnesium atom, and the polyvalent metal compound has a zirconium atom. It is especially preferable that it is a compound containing.

  The compound containing a zirconium atom, an aluminum atom or a magnesium atom that can be used in the present invention (excluding zirconium oxide and aluminum oxide) may be water-soluble or water-insoluble. It is preferable that the ink can be uniformly added to a desired position of the ink absorbing layer.

  Further, the compound containing a zirconium atom, an aluminum atom or a magnesium atom that can be used in the present invention may be any of a single salt and a double salt of an inorganic acid or an organic acid, an organic metal compound, a metal complex, Those that can be uniformly added to desired positions of the ink absorbing layer are preferred.

  Specific examples of the compound containing a zirconium atom that can be used in the present invention include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconate (for example, potassium salt), heptafluorozirconate. (For example, sodium salt, potassium salt or ammonium salt), octafluorozirconium salt (for example, lithium salt), fluorinated zirconium oxide, zirconium dichloride, zirconium trichloride, zirconium tetrachloride, hexachlorozirconium salt (for example, sodium Salt or potassium salt), zirconium oxychloride (eg, zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide oxide, zirconium triiodide, zirconium tetraiodide, zirconium peroxide Zirconium hydroxide, zirconium sulfide, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, potassium zirconium sulfate, zirconium selenate, zirconium nitrate, zirconyl nitrate, phosphoric acid Zirconium, zirconyl carbonate, zirconyl ammonium carbonate, zirconium acetate, zirconyl acetate, zirconyl ammonium acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconium phosphate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, Zirconium acetylacetonate, acetylacetone zirconium butyrate, zirconium stearate butyrate, zirco Um acetate, bis (acetylacetonato) dichloro zirconium and tris (acetylacetonato) such as chloro zirconium are exemplified.

  Among these compounds containing zirconium atoms, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconium oxychloride, zirconyl lactate and zirconyl citrate are preferable, and zirconium oxychloride, zirconyl ammonium carbonate and zirconyl acetate are particularly preferable.

  Specific examples of the compound containing an aluminum atom that can be used in the present invention include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, basic aluminum chloride (polyaluminum chloride), and tetrachloroalumine. Acid salts (for example, sodium salt), aluminum bromide, tetrabromoaluminate (for example, potassium salt), aluminum iodide, aluminate (for example, sodium salt, potassium salt, calcium salt), chloric acid Aluminum, aluminum perchlorate, aluminum thiocyanate, aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum phosphate Aluminum nitrate, aluminum hydrogen phosphate, aluminum carbonate, aluminum polysulfate silicate, aluminum formate, aluminum acetate, aluminum lactate, aluminum oxalate, aluminum isopropylate, aluminum butyrate, ethyl acetate aluminum diisopropylate, aluminum tris (acetylacetonate) , Aluminum tris (ethyl acetoacetate), aluminum monoacetylacetonate bis (ethyl acetoacetonate), and the like. Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate, and basic aluminum sulfate silicate are preferable.

  Specific examples of the compound containing a magnesium atom that can be used in the present invention include magnesium fluoride, magnesium acetate, magnesium bromide, magnesium chloride, magnesium formate, magnesium nitrate, magnesium sulfate, magnesium thiocyanate, magnesium thiosulfate, and sulfide. Examples thereof include magnesium, magnesium carbide, and magnesium phosphate. Among these, magnesium chloride, magnesium sulfate, and magnesium nitrate are preferable.

  Among these polyvalent metal compounds, particularly preferable ones are those exemplified as preferred compounds containing zirconium atoms, those exemplified as preferred compounds containing aluminum atoms, and preferred compounds containing magnesium atoms. Among those exemplified are zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconium oxychloride, zirconyl lactate, zirconyl citrate, basic aluminum chloride, magnesium chloride, magnesium sulfate and basic aluminum sulfate silicate. In particular, zirconium oxychloride, zirconyl ammonium carbonate and zirconyl acetate are preferable, and zirconium oxychloride is most preferable.

  The use amount of the cationic polymer or the water-soluble polyvalent metal compound is preferably 10% by mass or less, more preferably 8% by mass or less in terms of the mass ratio with respect to the inorganic fine particles, in order to suppress deterioration of ink absorbability. .

  As a method for adding a cationic polymer or a water-soluble polyvalent metal compound, in addition to a method in which it is directly added to a coating solution, a cationic resin or a water-soluble polyvalent metal compound is added after the recording paper is coated and dried. A method of overcoating with an aqueous solution and drying may also be used.

  It is preferable to add a water-soluble binder hardening agent for forming the ink absorbing layer to the ink jet recording paper of the present invention.

  The curing agent that can be used in the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and its salts are preferable, but other known ones can be used. Specifically, it is a compound having a group capable of reacting with a water-soluble binder or a compound that promotes the reaction between different groups of the water-soluble binder, and is appropriately selected depending on the type of the water-soluble binder. Specific examples of the curing agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

  Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts.

  Boric acid having a boron atom as a curing agent and a salt thereof may be used as a single aqueous solution or as a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax. The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, respectively, but by mixing both, a concentrated aqueous solution can be obtained and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely. The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder.

  In the recording paper of the present invention, the viscosity of the ink absorbing layer coating solution is preferably 0.010 to 0.300 Pa · s at 40 ° C., and a more preferable viscosity range is 0.025 to 0.100 Pa · s. If the viscosity of the coating liquid becomes too high, it cannot be supplied to the coating apparatus, resulting in poor liquid feeding.

  As the support that can be used in the present invention, those conventionally known for inkjet recording paper can be used as appropriate, and may be a water-absorbing support, but a non-water-absorbing support is particularly preferable. When an absorbent support is used, cockling may occur due to the support absorbing water in the ink, and the quality after printing is impaired.

  Examples of the water-absorbing support that can be used in the present invention include sheets and plates having general paper, cloth, wood, and the like. The paper support can be made from chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, CGP, RMP, TMP, CTMP, CMP and PGW, and wood pulp such as waste paper pulp such as DIP. It is. In addition, various fibrous materials such as synthetic pulp, synthetic fiber, and inorganic fiber can be appropriately used as a raw material as necessary. If necessary, various conventionally known additives such as sizing agents, pigments, paper strength enhancers, fixing agents, fluorescent whitening agents, wet paper strength agents, cationizing agents and the like are added to the paper support. be able to. The paper support can be produced with various paper machines such as a long net paper machine, a circular net paper machine, and a twin wire paper machine by mixing the above-mentioned fibrous material such as wood pulp and various additives. Further, if necessary, the paper can be subjected to size press treatment with starch, polyvinyl alcohol or the like, various coating treatments, or calendar treatment on a paper making stage or a paper machine.

Non-water-absorbing supports that can be preferably used in the present invention include transparent supports and opaque supports. Examples of the transparent support include films having materials such as polyester resins, diacetate resins, triatesate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, and celluloid. Among them, those having a property of resisting radiant heat when used for overhead projectors (OHP) are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is preferably 50 to 200 μm. Further, as the opaque support, for example, resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which white pigment or the like is added to at least one of the base paper, white pigment such as barium sulfate is added to polyethylene terephthalate. A so-called white pet is preferable. For the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer, the support is preferably subjected to corona discharge treatment, subbing treatment or the like prior to application of the ink absorbing layer. Furthermore, the inkjet recording paper of the present invention is not necessarily colorless, and may be a colored recording sheet.
In the ink jet recording paper of the present invention, it is particularly preferable to use a paper support obtained by laminating both sides of a base paper support with polyethylene because the recorded image is close to photographic image quality and a high-quality image can be obtained at low cost.

  Such a paper support laminated with polyethylene will be described below.

The base paper used for the paper support is made from wood pulp as a main raw material and, if necessary, paper making using synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester in addition to wood pulp. As 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. . However, the ratio of LBSP or LDP is preferably 10 to 70% by mass. The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching 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 the mass% of the 24 mesh residue defined by JIS-P-8207 and the 42 mesh residue. The sum of the mass% of the minute is preferably 30 to 70%. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less. The basis weight of the base paper is preferably 30 to 250 g, 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 generally 0.7 to 1.2 g / cm ³ (JIS-P-8118). 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. 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 that covers 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, and the like can also be used. In particular, the polyethylene layer on the ink absorbing layer side is preferably one in which rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness, as is widely done in photographic paper. The titanium oxide content is usually 3 to 20% by mass, preferably 4 to 13% by mass, based on polyethylene. Polyethylene-coated paper can be used as glossy paper, or when the polyethylene is melt-extruded onto the surface of the base paper and coated, a so-called molding process is performed to form a matte or silky surface that can be obtained with ordinary photographic paper These can also be used in the present invention. In the polyethylene-coated paper, the water content in the paper is particularly preferably maintained at 3 to 10% by mass.

  In the ink jet recording paper of the present invention, the method for applying the constituent layers such as the ink absorbing layer according to the present invention on the support can be appropriately selected from known methods. A preferred method is obtained by coating a coating liquid constituting each layer on a support and drying. In this case, two or more layers can be applied simultaneously. As the coating method, for example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferable. Used.

  Next, an inkjet ink (hereinafter also simply referred to as ink) used for printing an image on the inkjet recording paper of the present invention will be described.

  As the ink used for the inkjet recording paper of the present invention, a water-based ink composition, an oil-based ink composition, a solid (phase change) ink composition, or the like can be used, but the water-based ink composition (for example, per ink total mass) A water-based inkjet recording liquid containing 10% by mass or more of water can be particularly preferably used.

  As the colorant used in the ink, conventionally known water-soluble dyes such as acid dyes, direct dyes, reactive dyes, disperse dyes, pigments and the like can be used.

  The water-based ink composition is preferably used in combination with a water-soluble organic solvent. Examples of the water-soluble organic solvent that can be used in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl). Alcohol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol Etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol) Ether monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether , Triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, mole) Phosphorus, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N , N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides ( For example, dimethyl sulfoxide etc.), sulfones (for example, sulfolane etc.), urea, acetonitrile, acetone etc. are mentioned. Preferable water-soluble organic solvents include polyhydric alcohols. Furthermore, it is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether in combination. The water-soluble organic solvent may be used alone or in combination. The total amount of the water-soluble organic solvent added to the ink is 5 to 60% by mass, preferably 10 to 35% by mass.

  The ink composition used in the present invention may contain various known additions depending on the purpose of improving ejection stability, print head and ink cartridge compatibility, storage stability, image storability, and other various performances as necessary. Agents, such as viscosity modifiers, surface tension modifiers, specific resistance modifiers, film forming agents, dispersants, surfactants, UV absorbers, antioxidants, anti-fading agents, antifouling agents, rust inhibitors, etc. For example, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, urea resin Or organic latex fine particles such as melamine resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil Oil droplet fine particles, cationic or nonionic surfactants, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192 and 57 -878989, 60-72785, 61-146591, JP-A-1-95091 and 3-13376, etc., JP-A-59-42993, 59-52689 Fluorescent brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. described in Nos. 62-280069, 61-242871, and JP-A-4-219266 PH adjusters and the like.

  The ink composition has a viscosity at the time of flight of preferably 40 mPa · s or less, and more preferably 30 mPa · s or less. The ink composition has a surface tension during flight of preferably 20 mN / m or more, and more preferably 30 to 45 mN / m.

  The ink jet head used in the ink jet recording method using the ink jet recording paper of the present invention may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, a thermal type) Specific examples include an ink jet type, a bubble jet (registered trademark) type, and an electrostatic suction method (for example, an electrolysis control type, a slit jet type, etc.). I do not care.

  Then according to the present invention

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<Production of recording paper>
[Preparation of fine particle dispersion A]
Using a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd., 10 kg of gas phase method silica (trade name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., average particle diameter of primary particles: 14 nm) After sucking and dispersing in an aqueous solution obtained by adding 435 ml of ethanol to water at room temperature, pure water was added to make the total volume to 43.5 L to obtain a finished dispersion. This dispersion has a pH of 2.8 and contains 1% by mass of ethanol.

  Next, 40 ml of a 28% aqueous solution of the cationic polymer P-1 was added to 400 ml of this dispersion, pre-dispersed with a dissolver, and then sodium acetate in an amount necessary to adjust the pH to 4.5 was added. Furthermore, it was dispersed for 30 minutes at a peripheral speed of 9 m / sec using a sand mill disperser. The total amount of this dispersion was finished to 540 ml to prepare an almost transparent fine particle dispersion A. The fine particle dispersion B1 was filtered using a TCP-10 type filter manufactured by Advantex Toyo.

[Preparation of UV-polymerized polyvinyl alcohol aqueous solution B-1]
In accordance with the method described in JP-A-2000-181062, after reacting p- (3-methacryloxy-2-hydroxypropyloxy) benzaldehyde with polyvinyl alcohol having a polymerization degree of 3000 and a saponification degree of 88%, A polymerization initiator (manufactured by Nippon Kayaku Co., Ltd., Kayacure QTX) is added to the polyvinyl alcohol in a mass ratio of 1.8%, and an ultraviolet polymerization type polyvinyl alcohol aqueous solution B having a crosslinking group modification rate of 1 mol% and a solid content concentration of 8% by mass. -1 was prepared.

[Preparation of recording paper]
(Preparation of recording paper 1)
While stirring 528 ml of the fine particle dispersion A prepared above at 40 ° C., 188 ml of the above prepared UV polymerization type polyvinyl alcohol aqueous solution B-1 was gradually added, and then a pluronic nonionic surfactant (S-8). 50 ml of a 3% solution (water: isopropyl alcohol = 1: 1) and 10 ml of a 5% solution (water: isopropyl alcohol = 1: 1) of a cationic surfactant (S-4) were added. Pure water was added to a volume of 1000 ml to prepare a translucent ink absorbing layer coating solution 1.

Next, a polyethylene coated paper having both sides of a base paper having a thickness of 170 g / m ² coated with polyethylene (containing 8% anatase-type titanium oxide in the polyethylene on the ink absorption layer side, and 0.05 g on the ink absorption layer side). / have a gelatin subbing layer of m ^2, also in the ink absorbing layer having a back layer Tg comprises latex polymer of from about 80 ° C. the surface opposite the 0.2 g / m ^2), the The ink absorbing layer coating liquid 1 was applied with a wet film thickness of 200 μm using a bar coater. Immediately after coating, the sample is cooled for 20 seconds in a cooling zone maintained at 0 ° C., and irradiated with ultraviolet rays using a metal halide lamp having a main wavelength of 365 nm at an illuminance of 100 mw / cm ² and an energy amount of 30 mJ / cm ^2. Thereafter, it was dried in a hot air oven at 80 ° C. After drying, an aqueous solution of polybasic aluminum (manufactured by Taki Chemical Co., Ltd .: Takibine # 1500) is applied with a bar coater so as to be 0.4 g / m ² in terms of aluminum mass. The recording paper 1 was produced by drying. The contents of the surfactant (S-8) and the surfactant (S-4) in the recording paper 1 are 0.3 g / m ² and 0.1 g / m ² , respectively.

(Preparation of recording paper 2-18)
Recording paper 1 was prepared in the same manner as described above except that the types and addition amounts of pluronic-type nonionic surfactant (N) and cationic surfactant (C) were changed as shown in Table 1. 2-18 were produced.

(Preparation of recording sheets 19 and 20)
In the production of the recording papers 1 and 17, the recording papers 19 and 20 were prepared in the same manner except that the polybasic aluminum (Taki Chemical Co., Ltd .: Takibaine # 1500), which is a polyvalent metal compound, was not applied. Produced.

  The details of each surfactant used for the production of each recording paper shown in Table 1 are as follows.

Surfactant (S-1): Nonionic surfactant, polyoxyethylene octyl phenyl ether (Octapol 100, dynamic surface tension = 40.2 mN / m, manufactured by Sanyo Chemical Industries)
Surfactant (S-2): Nonionic surfactant, acetylene glycol (Surfinol 82, dynamic surface tension = 53.4 mN / m, manufactured by Nissin Chemical Industry Co., Ltd.)
Surfactant (S-3): Nonionic surfactant, acetylene glycol / ethylene oxide adduct (Surfinol 440, dynamic surface tension = 37.4 mN / m, manufactured by Nissin Chemical Industry Co., Ltd.)
Surfactant (S-4): Cationic surfactant, lauryltrimethylammonium chloride (Coatamine 24P, manufactured by Kao Corporation)
Surfactant (S-5): Cationic surfactant, oleylamine acetate (Pionin B-709, manufactured by Takemoto Yushi Co., Ltd.)
Surfactant (S-6): Cationic surfactant, lauryl pyridinium chloride (Pionin B-251, manufactured by Takemoto Yushi Co., Ltd.)
Surfactant (S-7): Cationic surfactant, perfluoroalkyltrimethylammonium salt (Megafax F-150, manufactured by Dainippon Ink & Chemicals, Inc.)
Surfactant (S-8): Nonionic surfactant, Pluronic type (Pionine P2310, molar ratio of oxyethylene group of about 10%, dynamic surface tension = 41.6 mN / m, manufactured by Takemoto Yushi Co., Ltd.)
Surfactant (S-9): Nonionic surfactant, Pluronic type (Pionin P1525, oxyethylene group molar ratio of about 25%, dynamic surface tension = 46.2 mN / m, manufactured by Takemoto Yushi Co., Ltd.)
Surfactant (S-10): Nonionic surfactant, Pluronic type (Pionine P3750, molar ratio of oxyethylene group: about 50%, dynamic surface tension = 48.0 mN / m, manufactured by Takemoto Yushi Co., Ltd.)
Surfactant (S-11): Nonionic surfactant, Pluronic type (Adekapluronic F77, oxyethylene group molar ratio of about 70%, dynamic surface tension = 57.0 mN / m, manufactured by Asahi Denka Co., Ltd.)
Surfactant (S-12): Nonionic surfactant, Pluronic type (Pionin P2280, molar ratio of oxyethylene group: about 80%, dynamic surface tension = 62.5 mN / m, manufactured by Takemoto Yushi Co., Ltd.)
Surfactant (S-13): Nonionic surfactant, Pluronic type (Adekapluronic TR702, oxyethylene group molar ratio of about 20%, dynamic surface tension = 45.8 mN / m, manufactured by Asahi Denka Co., Ltd.)
The dynamic surface tension of each of the nonionic surfactants described above was prepared by preparing a 0.3 mass% aqueous solution of each nonionic surfactant, and using BP2 (Germany) manufactured by Cruz as a dynamic surface tension measuring device. Is used, the foam is continuously generated at a liquid temperature of 35 ° C., and the dynamic surface tension at 20 ms is measured by the maximum bubble pressure method.

<Evaluation of recording paper>
Each of the produced recording sheets was evaluated according to the following method.

[Evaluation of bronzing resistance]
A black solid image was printed on each recording paper produced above using an ink jet printer PMG800 manufactured by Seiko Epson, and stored for one week at 23 ° C. and a relative humidity of 80%. Observing and assessing bronzing resistance according to the following criteria:

◎: No bronzing is observed at all. ○: A small portion of weak bronzing is observed. △: Some bronzing is observed, but the quality is practically acceptable. XX: Quality that causes extremely severe bronzing and is unbearable for appreciation In the above evaluation rank, if it is Δ or more, it is judged that the quality is practically preferable.

[Evaluation of dye print density]
A black solid image is printed on each recording paper using the inkjet printer under the maximum output condition, and the maximum reflection density of the printed image is measured with green light of X-Rite 938 (manufactured by X-Rite Co., Ltd.). The print density was evaluated. If the reflection density was 2.00 or higher, it was judged that the quality was satisfactory for practical use.

[Evaluation of gloss]
Gloss was evaluated by measuring the 60-degree gloss on the ink absorbing layer surface side of each recording paper using a variable angle gloss meter (VGS-1001DP) manufactured by Nippon Denshoku Industries Co., Ltd. If the glossiness is 30% or more, the quality is satisfactory for practical use.

[Evaluation of pigment print density]
For each recording paper, a solid yellow image was printed under the maximum output condition using an ink jet printer PM4000PX manufactured by Seiko Epson Corporation, and the maximum reflection density of the printed image was X-Rite 938 (manufactured by X-Rite Co., Ltd.). The print density was evaluated by measuring with blue light. When the reflection density was 1.30 or more, it was judged that the quality had no practical problem.

  Table 1 shows the evaluation results obtained as described above.

  As is apparent from the results shown in Table 1, the recording paper of the present invention having an ink absorbing layer containing a pluronic-type nonionic surfactant and a cationic surfactant has a print quality due to bronzing as compared to the comparative example. It can be seen that this is an inkjet recording paper in which the yellow density in the pigment ink print is improved in addition to the high print density and gloss without being deteriorated. In addition, in the pigment ink print, it was confirmed that the recording paper of the present invention showed a density equal to or higher than that of the comparative example as a result of the same evaluation for each density of magenta, cyan, and black. did it.

In addition, in the preparation of each recording paper described above, commercially available wet silica (trade name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd., average particle diameter of primary particles: 14 nm) used in the ink absorption layer was used. Tokuyama Co., Ltd., trade name: T-32, specific surface area 202 g / m ² , average secondary particle size 1.5 μm precipitated silica) is rotated in an aqueous medium at a peripheral speed of 20 m / sec. However, recording paper was prepared in the same manner except that wet silica having an average particle diameter of 200 nm prepared by gradually charging, pulverizing and dispersing was used, and the same evaluation was performed. It was not possible to obtain satisfactory results due to gloss degradation.

Claims (7)

On the support, there is a void-type ink absorbing layer containing at least inorganic fine particles having an average particle size of 100 nm or less and a hydrophilic polymer, and the ink absorbing layer comprises a pluronic-type nonionic surfactant and a cationic surfactant. An ink jet recording paper comprising: 2. The 0.3% by mass aqueous solution (35 ° C.) of the pluronic-type nonionic surfactant has a dynamic surface tension of 60 mN / m or less at 20 milliseconds as measured by a maximum bubble pressure method. The inkjet recording paper as described. The inkjet recording paper according to claim 1 or 2, wherein the cationic surfactant is a compound having a quaternary ammonium salt in the molecule. 4. The ink jet recording paper according to claim 3, wherein the compound having a quaternary ammonium salt in the molecule is lauryltrimethylammonium chloride. The mass ratio C / N of the cationic surfactant (C) and the pluronic nonionic surfactant (N) in the ink absorption layer is 0.05 or more and 0.50 or less. The inkjet recording paper of any one of -4. The inkjet recording paper according to claim 1, wherein the ink absorption layer contains a polyvalent metal compound. The inkjet recording paper according to any one of claims 1 to 6, wherein the support is a non-water-absorbing support.