JP3976144B2 - Inkjet recording medium - Google Patents

Description

  The present invention relates to an inkjet recording medium having suitability for pigment ink and dye ink.

  The ink jet recording method is rapidly becoming popular because it is easy to make full color, has less printing noise, and does not require development-fixing processing. In recent years, it is an image that is comparable to multicolor printing by plate making and color photographic methods. Is obtained. The ink jet recording method is a method in which fine droplets of ink are ejected from a nozzle to a recording medium at a high speed, and images and characters are recorded, and the ink contains a large amount of solvent. Therefore, the ink jet recording medium is required to have a property of quickly absorbing ink. In addition, due to the recent spread of computers and digital cameras, image quality (high color development, resolution and color reproducibility) similar to silver halide photography is required for the ink jet recording method, and in order to cope with this, ink absorption is high. A technique for providing an ink receiving layer on the surface of a recording medium has been developed. Furthermore, in order to apply the inkjet recording method to advertisements such as posters and labels with an adhesive layer on the back, inkjet recording has the advanced characteristics of improving the storability of printed images (water resistance, light resistance, etc.) Required for media.

  Conventionally, water-based dye ink has been mainly used in the ink jet recording system. Although this water-based dye ink uses a low molecular weight dye as a colorant, it has good color developability, but it easily bleeds due to adhesion of water or the like, or is exposed to light or gas for a long time due to the structure of the colorant. Discoloration, discoloration, and there are problems with the storability of recorded images and image fastness.

  Therefore, in order to improve the problem of dye ink and improve water resistance and light resistance, ink using a pigment as a colorant has been put into practical use (see, for example, Patent Documents 1 to 3). However, in the case of pigment ink, there are problems such as a decrease in printing density and inferior uniformity of solid printing portions. In addition, if a large amount of pigment ink is ejected to enhance color development, the colorant accumulates on the surface of the recording medium, resulting in a decrease in frictional resistance, resulting in smudges on the printed matter or the absorption of the solvent in the ink due to the accumulation of the colorant. Sometimes.

  As described above, in recent years, both dyes and pigments have been used as inks for ink jet recording, and in order to cope with this, recording media suitable for both dye inks and pigment inks are required. Therefore, a technique is disclosed in which the ink receiving layer includes an adhesive composed of inorganic fine particles and a vinyl chloride-vinyl acetate copolymer, and both recording properties of dye ink and pigment ink are imparted (for example, Patent Document 4). reference).

JP-A-11-20306 JP 2000-79752 A JP 2003-145916 A Japanese Patent Laid-Open No. 2001-270238

However, in the case of the techniques described in Patent Documents 1 to 3, the recording suitability using the pigment ink is improved, but the recording suitability using the dye ink is insufficient. In the case of the technique described in Patent Document 4, the print characteristics, particularly the print density and the uniformity of the solid print portion are not yet satisfactory.
Accordingly, an object of the present invention is to obtain an excellent image quality regardless of whether a dye ink or a pigment ink is used, and in particular, an ink jet which has high color developability, high ink absorbability, and excellent image uniformity in a solid print portion. It is to provide a recording medium.

In general, it has been known that a cationic polymer compound in an ink receiving layer of a recording medium is involved in fixing of a dye ink and a pigment ink in ink jet printing, but due to a difference in coloring mechanism between the dye ink and the pigment ink. Therefore, it has been difficult to realize an ink jet recording medium suitable for both inks.
As a result of intensive studies to solve the above-mentioned problems, the present inventors have completed the present invention by including a specific cationic polymer compound in a predetermined portion of the ink receiving layer.
The reason for this is not clear, but is considered as follows. That is, the dye ink is a water-soluble anionic polymer, and when the ink receiving layer contains a cationic substance having a high degree of cationization, the dye ink aggregates with the cationic substance, and the color developability is improved. On the other hand, since the pigment ink itself is particles, the color developability is improved by reducing the voids in the ink receiving layer so that the ink stays on the surface.
However, in the case of an ink receiving layer suitable for dye ink, the permeability of the pigment ink is high, and the pigment ink is deposited in the ink receiving layer or the support, so that the color developability of the pigment ink is lowered. On the other hand, in the case of an ink receiving layer suitable for pigment ink, the dye ink is not sufficiently absorbed by the ink receiving layer, and the dye ink overflows and blurs when mixed.
Therefore, the lower ink-receiving layer contains inorganic fine particles with high ink absorption and a low molecular weight cationic polymer compound, and the voids of the inorganic fine particles in the layer are filled with the cationic polymer compound, so that It is possible to prevent the pigment ink colorant penetrating from the ink receiving layer from being rapidly deposited in the lower ink receiving layer, and as a result, it is possible to improve the color developability of the pigment ink in the upper ink receiving layer. In addition, it is considered that the upper ink-receiving layer contains a high molecular weight cationic polymer compound having a high cationization density so that the dye ink can be aggregated and absorbed in this layer to improve the coloring property of the dye ink. It is done.

That is, the above-described object of the present invention is obtained by successively laminating two layers of an ink receiving layer each containing inorganic fine particles and a water-soluble binder on the surface of the support, of which the lower ink receiving layer has a number average. It is achieved by an ink jet recording medium comprising a cationic polymer compound having a molecular weight of 1,000 to 50,000, the upper ink-receiving layer containing a cationic polymer compound having a number average molecular weight of 80000 or more and a cationization density of 6.5 meq / g or more. It was. The cationization density of the cationic polymer compound in the lower ink receiving layer is preferably 2.5 to 6.5 meq / g. The lower layer and / or the upper ink receiving layer preferably contains 2 to 20 parts by weight of the cationic polymer compound with respect to 100 parts by weight of the inorganic fine particles. The upper ink receiving layer may be a cast coating layer.
Furthermore, the object of the present invention is to provide an ink receiving layer containing inorganic fine particles and a water-soluble binder on the surface of the support, and a region of 3 to 100 μm in thickness facing the support in the ink receiving layer. Contains a cationic polymer compound having a number average molecular weight of 1,000 to 50,000, and a region having a thickness of 5 to 150 μm from the outermost surface of the ink receiving layer has a number average molecular weight of 80000 or more and a cationization density of 6.5 meq / g or more. This was achieved by an ink jet recording medium characterized by containing a polymer compound.

  The ink jet recording medium of the present invention can obtain an excellent image quality using either a dye ink or a pigment ink, and particularly has high color developability and ink absorbability, and is excellent in image uniformity in a printing solid portion. .

  Embodiments of the present invention will be described below. The ink jet recording medium of the present invention is formed by laminating an ink receiving layer on the surface of a support.

  The support used in the present invention is not particularly limited, and examples thereof include paper, resin film, resin-coated paper, synthetic paper, vapor-deposited paper, pressure-sensitive adhesive sheet, non-woven fabric and cloth mainly composed of wood fibers and synthetic fibers. . Moreover, what processed these support bodies, gave printing, and bonded together can also be used. In particular, a highly absorbent material such as paper or a support having a coating layer is preferable.

  Examples of the paper used for the support include plain paper mainly composed of wood fibers, coated paper, neutral paper, and acidic paper. As pulp used in paper, chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, waste paper pulp such as DIP, pulp other than wood such as kenaf, etc. You can choose.

  In addition to the above pulp, various raw materials such as raw materials, fillers, sizing agents, cationic water-soluble resins such as cationized starch, paper strength enhancers such as polyacrylamide and starch, yield improvers, etc. One or more additives can be internally added. Examples of fillers include clay, talc, calcium carbonate, kaolin, calcined kaolin, aluminum oxide, aluminum hydroxide, and titanium oxide. Examples of the sizing agent include a sizing agent such as sulfate band, rosin, alkyl ketene dimer, and alkenyl succinic acid. In addition, pigment dispersants, thickeners, fluidity improvers, surfactants, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, coloring dyes, fluorescent whitening agents, ultraviolet rays Absorbent, antioxidant, antiseptic, antibacterial agent, water resistance, wet paper strength enhancer, dry paper strength enhancer, water retention agent, antistatic agent, lubricant, release agent, crosslinking agent, pH adjuster, saccharide If necessary, alcohols and the like can be appropriately added as long as the effects of the present invention are not impaired.

  Then, these are mixed, a paper web is formed by various conventionally known paper machines such as a long net paper machine, a circular net paper machine, and a twin wire paper machine, and dried to obtain a paper support. Moreover, you may use for a support what laminated | stacked the paper web and was made into the multilayer paper. In addition, starches such as oxidized starch and acetylated starch and derivatives thereof, polyvinyl alcohol and derivatives thereof, binders such as polyvinylpyrrolidone, polymers such as styrene, acrylic, olefin, maleic acid, polyamide, and copolymers combining these The sizing treatment can be performed with a surface sizing agent comprising Furthermore, a machine calendar, a super calendar, etc. can also be used as needed.

  Examples of the resin film used for the support include transparent, translucent and opaque polyesters and polyolefins. In particular, polyesters such as polyethylene terephthalate and polybutylene terephthalate, which are thermoplastic resins, and olefin resins such as polyethylene and polypropylene are preferably used. Here, the olefin resin includes not only one type of olefin resin but also a copolymer selected from two or more types, and other resins such as vinyl acetate, acrylic acid ester, methacrylic acid ester and the like. Mergers are also included. Furthermore, what formed the sheet | seat by mixing an inorganic filler and a small amount of organic fillers with the said thermoplastic resin, and formed the sheet | seat by performing a uniaxial or biaxial stretching process may be used as a support body. Further, a multilayer film obtained by laminating a plurality of the above resin films, or a laminated paper obtained by laminating a resin film on a paper substrate may be used as a support. In addition, ozone treatment or corona discharge treatment can be applied to improve the surface properties of the resin film.

  The ink receiving layer in the present invention is composed of two layers, and each layer contains inorganic fine particles, a water-soluble binder, and a cationic polymer compound having a predetermined molecular weight. First, components common to the ink receiving layers of the respective layers will be described.

  The inorganic fine particles in the ink receiving layer contribute to the adsorption of the dye ink and the pigment ink colorant and the absorbability of the ink solvent, and have functions such as serving as a carrier for other auxiliary agents. Examples of the inorganic fine particles include, for example, synthetic silica, colloidal silica, colloidal alumina, gas phase method silica, gas phase method alumina, boehmite, pseudoboehmite, aluminum hydroxide, alumina synthesized by gel method, precipitation method, dry method, and the like. Lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, white carbon, light calcium carbonate, heavy calcium carbonate, kaolin, calcined kaolin, talc, clay, calcium sulfate, Barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white and the like can be used. In addition, inorganic fine particles that have been modified such as cationization or silylation or whose shape has been changed can also be used. Further, one or more of the above inorganic fine particles can be used in combination.

  In particular, it is preferable to use synthetic silica or alumina excellent in ink absorbability, especially synthetic silica as the inorganic fine particles. Moreover, organic fine particles such as styrene plastic pigment, acrylic plastic pigment, vinyl plastic pigment, polyethylene, microcapsule, urea resin, melamine resin, and derivatives thereof, as long as the effects of the present invention are not impaired. Alternatively, a composite with inorganic fine particles having a core-shell structure or the like may be added.

  The water-soluble binder is for maintaining the properties of the ink receiving layer as a coating film. Examples of the water-soluble binder include polyvinyl alcohols such as polyvinyl alcohol, silyl-modified polyvinyl alcohol, and cation-modified polyvinyl alcohol, and modified products thereof, starches such as oxidized starch, acetylated starch, and etherified starch and derivatives thereof, Water-soluble polymer binders such as protein such as casein, gelatin, and soybean protein, and cellulose derivatives such as polyvinylpyrrolidone, carboxymethylcellulose, and hydroxyethylcellulose can be used. In particular, it is preferable to use polyvinyl alcohol from the viewpoint of transparency and strength, and it is particularly preferable to use completely saponified polyvinyl alcohol. One or more of the above water-soluble binders can be mixed and used.

The blending amount of the water-soluble binder is preferably 5 to 60 parts by weight with respect to 100 parts by weight of the inorganic fine particles. In addition to the water-soluble binder, other binders such as SB latex, NB latex, acrylic latex, vinyl acetate latex, ethylene vinyl acetate latex, polyurethane, and unsaturated polyester resin may be mixed. In this case, the blending amount of the mixture of the above-described water-soluble binder and these other binders is set within the above range with respect to the inorganic fine particles. When the blending amount of the water-soluble binder or the total of the water-soluble binder and the other binder is less than 5 parts by weight, the strength of the coating layer surface becomes insufficient, and 60 parts by weight. Exceeding this will impair ink absorbability.
From the viewpoint of improving ink absorbability, it is preferable to use the water-soluble binder alone or to contain 50% by weight or more of the water-soluble binder in a mixture with other binders. .

  Examples of the cationic polymer compound include primary amines, secondary amines, tertiary amines, quaternary ammonium salts and cyclic amines, or polymer compounds containing these salts as monomers. Specific examples include vinylimine, alkylamine, alkyleneamine, vinylamine, allylamine, alicyclic amine, epihalohydrin, dialkylaminoethyl methacrylate, dialkylaminoalkyl acrylate, dialkylaminoalkylacrylamide, diallyldimethylammonium salt, acrylamide, amidoamine, amidine, etc. Is a so-called polyethyleneimine resin, polyamine resin, polyamide resin, polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, polyamide polyamine epichlorohydrin resin, polydiallylamine resin, Examples thereof include dicyandiamide condensates. Two or more of these cationic polymer compounds can be used in combination.

  In particular, using either dye ink or pigment ink, excellent print quality, especially high print density and water resistance, dialkyl (alkylene) amine epihalohydrin and diallyldimethylammonium salt condensate (homopolymer), co-polymer Combinations and derivatives are preferred. A polymer (homopolymer), copolymer, and derivative of dialkyl (alkylene) amine epihalohydrin are most preferable because they hardly inhibit the ink absorbability of the ink receiving layer even at a low molecular weight.

  The cationic polymer compound may be used alone or as a mixture of a plurality of types. When a plurality of types are mixed, the number average molecular weight and cationization density of the mixture are within the specified range as the weight average value. There is a need.

  The production method of the cationic polymer compound described above is disclosed in, for example, JP-A-6-92012, JP-A-6-240154, JP-A-9-87561, JP-A-10-81065, and JP-A-10-152544. It is described in each publication.

  In the present invention, two ink receiving layers are successively laminated, of which the lower ink receiving layer contains a cationic polymer compound having a number average molecular weight of 1,000 to 50,000, and the upper ink receiving layer is a number average molecular weight. It is characterized by containing a cationic polymer compound having a cationization density of at least 80000 and a cationization density of 6.5 meq / g. Here, the “lower ink receiving layer” refers to the ink receiving layer on the support side, and the “upper ink receiving layer” refers to the ink receiving layer laminated on the surface of the lower ink receiving layer. In the present invention, it is essential that each of the ink receiving layers is laminated continuously. For example, another layer may be interposed between the lower ink receiving layer and the support, Further, another layer may be laminated on the surface of the upper ink receiving layer.

  With the layer configuration as described above, in the lower ink receiving layer, a cationic polymer compound having a relatively low molecular weight enters the voids of the layer and the pores of the inorganic fine particles, whereby the lower ink receiving layer itself It is considered that the voids are reduced. For this reason, the ink colorant component (coloring pigment, water-soluble dye, etc.) is prevented from rapidly penetrating into the lower ink receiving layer, and as a result, the colorant is reliably held in the upper ink receiving layer. It is considered that the color developability of pigment ink and dye ink is improved. And in order to suppress the penetration of the ink component from the upper layer side in this way in the lower ink receiving layer, the lower ink receiving layer and the upper ink receiving layer are continuously laminated, that is, between each ink receiving layer. It is necessary not to intervene other layers. On the other hand, since the upper ink receiving layer contains a cationic polymer compound having a relatively high molecular weight and a high cationization density, the ink solvent absorbability is high, and the ink coloring in this layer becomes clear.

  Further, normally, each ink receiving layer is formed by coating. As described above, since the voids in the lower ink receiving layer are filled with a cationic polymer compound having a relatively low molecular weight, the upper ink receiving layer is formed. At the time of coating, the water-soluble binder or the like in the coating liquid is prevented from rapidly sinking (sinking) into the lower ink receiving layer. For this reason, the proportion of the water-soluble binder in the upper ink-receiving layer is increased and a dense structure is formed, and as a result, the color developability of the pigment ink in the upper ink-receiving layer is improved. It is done.

  Note that when only the lower ink-receiving layer is formed without providing the upper ink-receiving layer, the ink solvent absorbs poorly, so ink overflows, blurring or unevenness of the image occurs especially when printing with dye ink. It becomes easy.

  The number average molecular weight of the cationic polymer compound in the lower ink receiving layer is 1,000 to 50,000, preferably 2,000 to 30,000. If the number average molecular weight of the cationic polymer compound is less than 1000, the voids in the lower ink-receiving layer and the pores of the inorganic fine particles are filled with the cationic polymer compound, and the ink (solvent) absorbs. Deterioration occurs, ink overflow, image bleeding, and ink drying property decrease. On the other hand, when the number average molecular weight exceeds 50,000, the voids in the lower ink receiving layer and the pores of the inorganic fine particles are not sufficiently filled with the cationic polymer compound, so that the penetration of the ink becomes too fast, and the dye ink When printing is performed, the colorant (dye ink) is fixed to the lower underlayer or the support further lower than the lower ink receiving layer, resulting in back-through and a decrease in print density.

  Further, the cationization density of the cationic polymer compound in the lower ink receiving layer is preferably 2.5 to 6.5 meq / g, particularly preferably 3.0 to 6.0 meq / g. When the cationization density is less than 2.5 meq / g, the ink absorbability is inferior when the dye ink is used, and when it exceeds 6.5 meq / g, the ink is absorbed faster and penetrates from the upper ink receiving layer. The colorant thus penetrated into the lower ink receiving layer, resulting in a decrease in color developability.

The number average molecular weight of the cationic polymer is a value measured by GPC (gel permeation chromatography). Moreover, the cationization density of the cationic polymer was measured with a particle surface charge measuring device (MUTEC TOLEDO DL-50) using a 0.001 mol / L polyvinyl potassium sulfate (PVSK) solution as a titrant. It is the value obtained by the calculation formula.

  The upper ink receiving layer has a number average molecular weight of 80,000 or more, preferably 100,000 to 10,000,000, and a cationization density of 6.5 meq / g or more, preferably 7.0 to 12.0 meq /. g cationic polymer compound. Since such a cationic polymer compound has a high molecular weight and a high cationization density, it is considered that the dye ink can be easily aggregated and absorbed in the upper ink-receiving layer, and the coloring property of the dye ink can be improved.

  Here, if the number average molecular weight of the cationic polymer compound in the upper ink-receiving layer is less than 80000, the ink solvent absorbability in this layer is deteriorated, which causes the image to bleed or the ink to overflow. On the other hand, the higher the number average molecular weight, the better the fixing ability of the ink and the better the color development of the ink. However, if the number average molecular weight is too large, the viscosity of the coating liquid increases and the coating property deteriorates. Since the work amount may not be ensured, it is preferable to set it to 10,000,000 or less.

  Further, when the cationization density of the cationic polymer compound in the upper ink receiving layer is less than 6.5 meq / g, the color developability of the dye ink is particularly deteriorated. On the other hand, the higher the cationization density, the better the fixing ability of the ink. However, aggregation tends to occur and the compatibility with other components in the coating liquid may decrease, so that it is 12.0 meq / g or less. It is preferable to do this.

  This cationic polymer compound can be selected from those used for the upper and lower ink-receiving layers, and the same cationic polymer compound may be used for each ink-receiving layer, or different ones. May be used. Furthermore, the above-mentioned cationic polymer compound can be used singly or as a mixture of a plurality of types, but when a plurality of types are mixed, the number average molecular weight and cationization density of the mixture are within the specified range as the weight average value. The necessary points are the same as in the case of the lower ink receiving layer.

  In the present invention, when the ink receiving layer is formed by being divided into a plurality of layers, it may be impossible to distinguish whether the ink receiving layer after drying is one layer or two layers. Therefore, when the support surface has an ink receiving layer containing inorganic fine particles and a water-soluble binder, a region having a thickness of 3 to 100 μm facing the support in the ink receiving layer has a number average molecular weight of 1000. A cationic polymer compound having a number average molecular weight of 80000 or more and a cationization density of 6.5 meq / g or more in a region having a thickness of 5 to 150 μm from the outermost surface of the ink receiving layer. What is to be included is also included in the present invention.

  The lower and upper ink receiving layers preferably contain 2 to 20 parts by weight, particularly 3 to 15 parts by weight, of the cationic polymer compound with respect to 100 parts by weight of the inorganic fine particles. If the amount of the cationic polymer compound is less than 2 parts by weight, the effect of the cationic polymer compound (improvement of ink fixing ability and print density) does not occur, and if it exceeds 20 parts by weight, the ink receiving layer The ink absorptivity of the ink is lowered, which causes unevenness and blurring of the printed image.

The thickness of the lower ink receiving layer is preferably 3 to 100 nm, more preferably 5 to 80 nm. The thickness of the upper ink receiving layer is preferably 5 to 150 nm, more preferably 8 to 120 nm. In order to obtain such a layer thickness by coating, for example, the dry coating amount of the lower ink-receiving layer is preferably 3 to 25 g / m ² , particularly 5 to 20 g / m ² , The dry coating amount of the upper ink receiving layer is preferably 3 to 40 g / m ² , particularly 5 to 30 g / m ² . However, the coating amount may vary depending on the various components of the coating liquid, the types of the inorganic fine particles and the water-soluble binder, the drying conditions and the blending ratio, but has a predetermined ink absorption capacity, The coating amount is adjusted so that the adhesive strength between the ink receiving layer and the support does not cause a practical problem.

If the dry coating amount of the lower and upper ink-receiving layers is less than 3 g / m ² , the surface of the support (and other layers) cannot be completely covered, and the ink absorbability is insufficient. As a result, uneven absorption occurs, which adversely affects printing performance. Even if the dry coating amounts of the lower and upper ink-receiving layers exceed the specified ranges, the effect is saturated and waste occurs. In addition, when the dry coating amount of the whole ink receiving layer combined with each of the ink receiving layers exceeds 50 g / m ² , the adhesive strength with the support or the under layer is lowered, which is a practical problem, This is not preferable because peeling of the ink receiving layer from the called support occurs.

  In addition, each ink receiving layer includes a sizing agent, a pigment dispersant, a thickener, a fluidity improver, a surfactant, an antifoaming agent, an antifoaming agent, a release agent, a foaming agent, a penetrating agent, a coloring dye, Optical brightener, UV absorber, antioxidant, antiseptic, antibacterial agent, waterproofing agent, wet paper strength enhancer, dry paper strength enhancer, water retention agent, antistatic agent, lubricant, release agent, crosslinking agent , PH adjusters, saccharides, alcohols, and the like can be appropriately contained within the range that does not impair the effects of the present invention.

  The ink receiving layers may be provided on one side or both sides of the support. When each ink receiving layer is provided on one side of the support, it is also possible to provide a coating layer on the surface of the support opposite to the ink receiving layer for purposes such as curl correction or improved transportability, antistatic, and peeling. . Further, an anchor layer may be provided between the support and the lower ink-receiving layer, and a surface modifying layer to which a brightener or a lubricant is added may be provided on the surface of the upper ink-receiving layer. The surface modification layer can be formed by coating, for example. In particular, it is preferable to provide a glossy layer on the surface of the upper ink receiving layer because the gloss of the recording surface is improved.

  Further, after coating the lower ink-receiving layer, the upper ink-receiving layer may be applied and formed while the coated surface is in a wet state.

  The ink receiving layer described above is mainly composed of the inorganic fine particles and the water-soluble binder, and after suitably impregnating or coating the surface of the support with a coating liquid containing the cationic polymer compound and other components, It can be formed by drying. Any known method can be used as the impregnation method and the coating method. For example, various coating machines such as blade coaters, roll coaters, air knife coaters, bar coaters, gate roll coaters, curtain coaters, short dwell coaters, gravure coaters, brush coaters, kiss coaters, squeeze coaters, die coaters, commas Various apparatuses such as a coater, a flexographic gravure coater, and a size press can be applied by using an on-machine or an off-machine.

  Also, after forming the ink-receiving layer by impregnation or coating, if necessary, use a calender device such as a machine calendar, super calendar, or soft calender with heating or at room temperature on or off-coating the surface of the ink-receiving layer. It is also possible to do.

  Further, after applying a predetermined treatment liquid to the wet ink-receiving layer by the impregnation or coating, the ink-receiving layer is pressure-bonded to a heated mirror-finished surface and dried to make the surface of the ink-receiving layer glossy. You may give what is called a cast coat. The ink receiving layer when applying the treatment liquid may be in a wet state or in a dry state. In particular, if the treatment liquid is applied to the wet ink receiving layer, a copy of the mirror-finished surface is obtained. Since it is easy to remove and can reduce the minute unevenness on the surface, it is easy to obtain a glossiness equivalent to that of a silver salt photograph. Then, after the treatment liquid is applied, it may be dried by an ordinary method such as a steam heater, a gas heater, an infrared heater, an electric heater, a hot air heater, a microwave, or a cylinder dryer.

As the ink for ink jet recording to which the ink jet recording medium of the present invention is applied, a water-based ink composition, an oil-based ink composition, a solid (phase change) ink composition, and the like can be used. , Water-based inkjet recording liquid containing 10% by mass or more of water per total mass of the ink) can be particularly preferably used.
As the colorant used in the ink, a dye ink using an acid dye, a direct dye, a reactive dye, or a disperse dye, an organic pigment such as an insoluble pigment or a lake pigment, and a pigment ink using carbon black or the like are used. be able to.

  In the ink jet recording method using a dye ink, an ink containing an anionic compound such as a water-soluble dye having an anionic group is particularly preferable. Examples of the water-soluble dye used in this case include a water-soluble direct dye having an anionic group such as a sulfone group and a carboxyl group, an acid dye, and a reactive dye. Such water-soluble dyes can be used in a proportion of about 0.1 to 20% by weight.

  In an ink jet recording method using a pigment ink, an organic pigment such as an insoluble pigment or a lake pigment, carbon black, or the like can be used as a colorant.

  A pigment dispersant may be used for these pigments as necessary, and various dispersing machines can be used as a method for dispersing the pigment. It is also preferable to use a centrifugal separator or a filter for the purpose of removing the coarse particles of the pigment dispersion.

  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, polyhydric alcohols, polyhydric alcohol ethers, amines, amides, heterocycles, sulfoxides, sulfones, 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. One or more water-soluble organic solvents may be used 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 may be prepared by adding various known additives such as viscosity according to the purpose of improving ejection stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Adjusting agents, surface tension adjusting agents, specific resistance adjusting agents, film forming agents, dispersants, surfactants, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust inhibitors, etc. are appropriately selected and used. be able to.

  The ink jet recording medium of the present invention is produced by applying a coating liquid to be the lower ink receiving layer to the support, drying it appropriately, and applying and drying the coating liquid to be the upper ink receiving layer. be able to.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples. Further, the following “parts” and “%” are parts by weight and% by weight unless otherwise specified.

(Manufacture of support)
90 parts of hardwood bleached kraft pulp and 10% of softwood bleached kraft pulp were mixed and beaten to adjust the freeness to 400 ml. .3 parts was added, and after paper making and drying with a known long paper machine, oxidized starch was applied by a size press so that the dry coating amount per side was 1.0 g / m ^2, and the basis weight was 85 g. A / m ² support was produced.

(Formation of undercoat layer (lower ink receiving layer))
Using the following coating liquid A, the coating liquid A was applied to one side of the support by a bar blade coater so that the dry coating amount was 8 g / m ² to form an undercoat layer.
Coating liquid A: Synthetic silica (trade name: X-60 manufactured by Tokuyama) 100 parts, polyvinyl alcohol (water-soluble binder, product name: PVA-117 Kuraray) 30 parts, ethylene vinyl acetate copolymer (trade name) : BE7000 manufactured by Chuo Rika Kogyo Co., Ltd.) 4 parts, styrene acrylic resin (size agent, trade name: Polymaron 360 manufactured by Arakawa Chemical Industries), cationic polymer compound (number average molecular weight 10,000, cationization density 5.0 meq / 8 parts of polyamine epichlorohydrin (g) was added, and an antifoaming agent (auxiliary) and dilution water were added and stirred and mixed to prepare a coating solution having a solid content concentration of 22%.

(Formation of topcoat layer (upper ink receiving layer))
Using the following coating liquid B, the coating liquid B was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² to obtain an ink jet recording medium.
Coating solution B: Exactly the same as coating solution A except that 8 parts of polyamine epichlorohydrin having a number average molecular weight of 100,000 and a cationization density of 7.0 meq / g were used as the cationic polymer compound. Thus, a coating solution having a solid content concentration of 22% was prepared.

(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.

(Formation of undercoat layer)
Using the following coating liquid C, the coating liquid C was applied to one side of the support with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
Coating liquid C: As a cationic polymer compound, 4.8 parts of polyamine epichlorohydrin having a number average molecular weight of 10,000 and a cationization density of 5.0 meq / g, and a number average molecular weight of 100,000 and a cationization density of 7 A coating solution having a solid content concentration of 22% was prepared in exactly the same manner as the coating solution A, except that 3.2 parts of polyamine epichlorohydrin at 0.0 meq / g was used in combination. The number average molecular weight of the entire cationic polymer compound in this coating solution was 46,000, and the cationization density was 6.2 meq / g. (Average value of the mixture of each cationic polymer compound)

(Formation of top coat layer)
Using the following coating liquid D, the coating liquid D was applied onto the undercoat layer by a curtain coater so that the dry coating amount was 10 g / m ² , thereby obtaining an ink jet recording medium.
Coating liquid D: Solid content concentration 22 in exactly the same manner as the coating liquid B except that the blending amount of polyvinyl alcohol (water-soluble binder, trade name: PVA-117 Kuraray) was 40 parts. % Coating solution was adjusted.

(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.

(Formation of undercoat layer)
Using the following coating liquid E, the coating liquid E was applied to one side of the support by a bar blade coater so that the dry coating amount was 5 g / m ² to form an undercoat layer.
Coating liquid E: Except that 8 parts of diallyldimethylammonium salt having a number average molecular weight of 3,000 and a cationization density of 5.0 meq / g were used as the cationic polymer compound, exactly the same as the coating liquid A described above. Thus, a coating solution having a solid content concentration of 22% was prepared.

(Formation of top coat layer)
Using the following coating solution F, the coating solution F was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² to obtain an ink jet recording medium.
Coating solution F: The above coating solution A except that 8 parts of polyamine epichlorohydrin having a number average molecular weight of 1,000,000 and a cationization density of 7.0 meq / g were used as the cationic polymer compound. In exactly the same manner, a coating solution having a solid concentration of 22% was prepared.

(Manufacture of support)
Add 10 parts of talc, 1.0 part of aluminum sulfate, 0.1 part of synthetic sizing agent, and 0.3 part of yield improver to pulp adjusted to 350 ml of hardwood bleached kraft pulp and adjusted to a freeness of 350 ml. Then, after papermaking and drying with a known long paper machine, oxidized starch is applied by a size press so that the dry coating amount per side is 1.5 g / m ^2, and machine calendar treatment is performed after drying. A support with an amount of 150 g / m ² was produced.

(Formation of undercoat layer)
Using the following coating solution G, the coating solution was applied to one side of the support by a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
Coating liquid G: The above coating liquid, except that 4 parts of dialkylamine ammonia epichlorohydric lysidyl ether copolymer having a number average molecular weight of 18,000 and a cationization density of 4.3 meq / g were used as the cationic polymer compound. In exactly the same manner as A, a coating solution having a solid content concentration of 22% was prepared.

(Formation of top coat layer)
Using the following coating liquid H, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 10 g / m ² , thereby obtaining an ink jet recording medium.
Coating liquid H: Exactly the same as coating liquid A except that 8 parts of diallyldimethylammonium acrylamide having a number average molecular weight of 200,000 and a cationization density of 6.6 meq / g were used as the cationic polymer compound. Thus, a coating solution having a solid content concentration of 22% was prepared.

(Manufacture of support)
A support was produced in exactly the same manner as in Example 4.

(Formation of undercoat layer)
Using the coating liquid A, the coating liquid was applied to one side of the support with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.

(Formation of top coat layer)
Using the following coating liquid I, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² to form a topcoat layer. Thereafter, soft calendering was performed at room temperature under a linear pressure of 50 kg / cm.
Coating liquid I: As synthetic silica, 50 parts of synthetic silica (trade name: X-37B manufactured by Tokuyama) and 50 parts of colloidal silica (trade name: PS-L manufactured by Nissan Chemical Industries) are used as a water-soluble binder. Except for using 10 parts of alcohol (trade name: PVA-217, manufactured by Kuraray) and using 8 parts of polyallylamine having a number average molecular weight of 150,000 and a cationization density of 10.9 meq / g as a cationic polymer compound. In exactly the same manner as coating liquid A, a coating liquid having a solid content concentration of 22% was prepared.

(Glossy layer formation)
Using the following coating liquid J, the coating liquid was applied onto the top coat layer with a bar blade coater so that the dry coating amount was 0.5 g / m ² to obtain an ink jet recording medium. Thereafter, soft calendering was performed at room temperature under a linear pressure of 50 kg / cm.
Coating liquid J: Diluted water was added to 100 parts of a brightener (trade name: B-14 manufactured by Harima Kasei), and the mixture was stirred and mixed to prepare a coating liquid having a solid content concentration of 30%.

(Manufacture of support)
65% by weight of polypropylene (having a melt flow rate (solution index) of 25 g / 10 min and a density of 0.91 g / cm ³ ) is melted, and calcium carbonate and titanium oxide as an inorganic filler are mixed in a weight ratio of What was adjusted to 95: 5 was added and mixed by 35% by weight. This is designated as resin A. Also, a polypropylene having the same physical properties as the above was prepared without containing the inorganic filler. This is designated as resin B.
Then, coextruded at a temperature of 290 ° C. using a coextrusion T die so that the resin B becomes the lower layer and the resin A becomes the upper layer on both sides of the high-quality paper having a basis weight of 48 g / m ² , and cooling. A laminated sheet was obtained by pressure bonding with a roll. Next, corona discharge treatment was performed on both surfaces of the laminated sheet to produce a support.

(Formation of undercoat layer)
Using the following coating liquid K, the coating liquid was applied to one side of the support by a curtain coater so that the dry coating amount was 10 g / m ² , thereby forming an undercoat layer.
Coating liquid K: A coating liquid having a solid content concentration of 22% was prepared in exactly the same manner as the coating liquid A except that the blending amount of polyvinyl alcohol was 40 parts.

(Formation of top coat layer)
Using the coating liquid D, the coating liquid was applied onto the undercoat layer with a curtain coater so that the dry coating amount was 15 g / m ² , thereby obtaining an ink jet recording medium.

(Manufacture of support)
A support was produced in exactly the same manner as in Example 4.

(Formation of undercoat layer)
Using the following coating liquid L, the coating liquid was applied to one side of the support by a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
Coating liquid L: 100 parts of synthetic silica (trade name: X-37B, manufactured by Tokuyama) is used as the synthetic silica, 20 parts of polyvinyl alcohol (trade name: PVA-117, manufactured by Kuraray) and SB latex are used as the water-soluble binder. Product name: LX438C, manufactured by Sumitomo Chemical Co., Ltd.) 5 parts, the sizing agent content was changed to 5 parts, and the cationic polymer compound content was changed to 4 parts. In exactly the same manner as A, a coating solution having a solid content concentration of 22% was prepared.

(Formation of top coat layer)
Using the coating liquid M below, the coating liquid is applied on the undercoat layer by a roll coater so that the dry coating amount is 20 g / m ^2, and the coating layer is in a wet state. Then, it is coagulated using the following coagulation liquid N, and then the coating layer is pressure-bonded to the surface of the mirror drum heated to 105 ° C. via a press roll for 20 seconds, and the mirror surface is copied (the above process is referred to as “cast coating treatment”). Inkjet recording medium having a basis weight of 180 g / m ² was obtained.
Coating liquid M: 100 parts of synthetic silica (trade name: X-37B manufactured by Tokuyama) is used as the synthetic silica, and 15 parts of polyvinyl alcohol (trade name: PVA-227 manufactured by Kuraray) is used as the water-soluble binder. The solid content concentration was 28 exactly the same as the coating liquid A except that 4 parts of polyamine epichlorohydrin having a number average molecular weight of 100,000 and a cationization density of 7.0 meq / g was used as the conductive polymer compound. % Coating solution was adjusted.
Coagulating liquid N: Borax (anhydride equivalent) 1.5%, boric acid 3%, and release agent (trade name: FL-48C, manufactured by Toho Chemical Co., Ltd.) 0.2% were mixed, and the solid content concentration was 4.7%. The coagulation liquid was adjusted.

(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.
(Formation of undercoat layer)
Using the following coating solution R, the coating solution was applied to one side of the support by a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
Coating solution R: A coating solution having a solid content concentration of 22% was prepared in exactly the same manner as the coating solution A except that the amount of the cationic polymer compound was changed to 25 parts.
(Formation of top coat layer)
Using the following coating liquid S, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby obtaining an ink jet recording medium.
Coating liquid S: A coating liquid having a solid content concentration of 22% was prepared in exactly the same manner as the coating liquid B except that the blending amount of the cationic polymer compound was changed to 25 parts.

<Comparative Example 1>
(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.
(Formation of undercoat layer)
Using the coating liquid A, the coating liquid was applied to one side of the support with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
(Formation of top coat layer)
Using the coating liquid A, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² to obtain an ink jet recording medium.

<Comparative example 2>
(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.
(Formation of undercoat layer)
Using the coating liquid B, the coating liquid was applied to one side of the support with a bar blade coater so that the dry coating amount was 8 g / m ² to form an undercoat layer.
(Formation of top coat layer)
Using the coating liquid B, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby obtaining an ink jet recording medium.

<Comparative Example 3>
(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.
(Formation of undercoat layer)
Using the coating liquid B, the coating liquid was applied to one side of the support with a bar blade coater so that the dry coating amount was 8 g / m ² to form an undercoat layer.
(Formation of top coat layer)
Using the coating liquid A, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² to obtain an ink jet recording medium.

<Comparative example 4>
(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.
(Formation of undercoat layer)
Using the following coating liquid P, the coating liquid was applied to one side of the support with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
Coating solution P: 4.0 parts of polyamine epichlorohydrin having a number average molecular weight of 10,000 and a cationization density of 5.0 meq / g as a cationic polymer compound, and a number average molecular weight of 100,000 and a cationization density of 7.0 meq A coating solution having a solid content concentration of 22% was prepared in exactly the same manner as the coating solution A except that 4.0 parts of polyamine epichlorohydrin / g was used in combination. The number average molecular weight of the entire cationic polymer compound in this coating solution was 55.000, and the cationization density was 6.0 meq / g.
(Formation of top coat layer)
Using the coating liquid P, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby obtaining an ink jet recording medium.

<Comparative Example 5>
(Manufacture of support)
A support was produced in exactly the same manner as in Example 1.
(Formation of undercoat layer)
Using the following coating solution Q, the coating solution was applied to one side of the support by a bar blade coater so that the dry coating amount was 8 g / m ² , thereby forming an undercoat layer.
Coating solution Q: Exactly the same as coating solution A except that 8 parts of polyamine epichlorohydrin having a number average molecular weight of 100,000 and a cationization density of 4.0 meq / g was used as the cationic polymer compound. Thus, a coating solution having a solid content concentration of 22% was prepared.
(Formation of top coat layer)
Using the coating liquid B, the coating liquid was applied onto the undercoat layer with a bar blade coater so that the dry coating amount was 8 g / m ² , thereby obtaining an ink jet recording medium.

<Comparative Example 6>
(Manufacture of support)
A support was produced in exactly the same manner as in Example 4.
(Formation of undercoat layer)
Using the following coating liquid T, the coating liquid was applied to one side of the support with a bar blade coater so that the dry coating amount was 20 g / m ² , thereby forming an undercoat layer.
Coating liquid T: Exactly the same as the coating liquid L, except that 4 parts of polyamine epichlorohydrin having a number average molecular weight of 100,000 and a cationization density of 7.0 meq / g was used as the cationic polymer compound. Thus, a coating solution having a solid content concentration of 22% was prepared.
(Formation of top coat layer)
In the same manner as in Example 7, the top coat layer was formed and the cast coat treatment was performed to obtain an inkjet recording medium having a basis weight of 180 g / m ² .

<Reference example>
PM mat paper (Seiko Epson Corporation), which is a commercially available inkjet paper, was prepared.

(Evaluation)
About the recording medium of each said Example and comparative example, it printed by the inkjet printer using pigment ink and dye ink, respectively, and evaluated by the method shown below.
In the case of pigment ink, PM-4000PX (trade name) manufactured by Seiko Epson is used as an inkjet printer, and the printer driver attached to the printer is set to “MC mat” for the paper and the mode setting is “recommended setting (clean)”. It was. The black ink used was a combination of matte black ink and gray ink. However, in Example 7 and Comparative Example 8 which are cast coated paper, the printer driver settings are “MC glossy paper” for the paper, the mode setting is “recommended setting (clean)”, and the black ink combination is photo Black ink and gray ink were used.
In the case of dye ink, use Seiko Epson's PM-970C (trade name) as an ink jet printer, set the printer driver attached to the printer to “PM Matte” and set the mode setting to “Recommended setting (clean)” It was. However, in the case of Example 7 and Comparative Example 8, the printer driver settings are “EPSON glossy paper” for the paper and “recommended setting (clean)” for the mode setting.

(Color development)
Solid images of black, cyan, magenta, and yellow were prepared and printed using spreadsheet software “Excel” manufactured by Microsoft Corporation. After the recording medium after printing is left in a constant temperature and humidity chamber for 24 hours, the printing density of each color is measured using a Macbeth densitometer (trade name: RD915, manufactured by Macbeth), and the total of the obtained measurement values ( Macbeth 4 color meter).
In the case of pigment ink ○: The total of four colors is 4.70 or more.
Δ: The total of four colors is 4.60 or more and less than 4.70.
X: The total of four colors is less than 4.60.
In the case of dye ink ○: The total of four colors is 6.70 or more.
Δ: The total of four colors is 6.50 or more and less than 6.70.
X: The total of four colors is less than 6.50.

(Ink absorption)
The solid images of red and green were printed side by side, and the solid images of blue and yellow were printed side by side in the same manner.
○: The boundary portion is clear and no bleeding is observed.
(Triangle | delta): Although a boundary part is a little unclear, a bleeding is not recognized.
X: The boundary portion is unclear and bleeding is observed.

(Image reproducibility)
A female image (ISO / JIS-SCID N1 portrait) was printed, and the degree of vividness on the human eye was evaluated visually.
○: Color balance is good.
Δ: Color balance is slightly poor.
×: Color balance is poor.

  The obtained results are shown in Tables 1 and 2. In each table, there is no practical problem if it is evaluated as ◯ or Δ, but there is a problem in practice when the evaluation is ×.

  As is clear from Tables 1 and 2, the ink jet recording media of Examples 1 to 8 are excellent in print quality (color developability, ink absorbability, and image reproducibility) regardless of whether pigment ink or dye ink is used. Yes. In particular, in Example 5 in which a glossy layer was provided on the outermost surface, the print density was high, and in Example 7 in which the top coat layer (upper ink receiving layer) was cast-coated, the print density was highest. . In Example 8 in which the amount of the cationic polymer compound in the undercoat layer exceeded 20 parts by weight with respect to 100 parts of the inorganic fine particles, the ink absorptivity was evaluated as △, but there was no practical problem. It was.

  On the other hand, in the case of Comparative Example 1 in which the number average molecular weight of the cationic polymer compound in the topcoat layer is less than 80,000, the printing quality (coloring property and image reproducibility) when using the dye ink was lowered. In the case of Comparative Example 2 in which the number average molecular weight of the cationic polymer compound in the undercoat layer (lower ink receiving layer) exceeded 50,000, the print quality (color development) when using the pigment ink was lowered. In the case of Comparative Example 3 in which the number average molecular weight of the cationic polymer compound in the undercoat layer exceeds 50,000 and the number average molecular weight of the cationic polymer compound in the topcoat layer is less than 80,000, The print quality (color development and image reproducibility) when using ink was lowered.

  In the case of Comparative Example 4 in which the number average molecular weight of the cationic polymer compound of the topcoat layer was less than 80000, the print quality (color developability) when using the dye ink was lowered. In the case of Comparative Example 5 in which the number average molecular weight of the cationic polymer compound in the undercoat layer exceeded 50,000, the print quality (color development) when using the pigment ink was lowered.

In the case of Comparative Example 6 in which the number average molecular weight of the cationic polymer compound in the undercoat layer exceeded 50,000, the print density with the dye ink was improved because of the cast coating treatment, but the pigment ink was used. The color developability and print density were reduced.
The reference example is the evaluation result of a commercially available ink jet recording paper (manufactured by Epson). The commercially available product has a low color developability when using either a pigment ink or a dye ink, and clearly shows the superiority of the present invention. became.

Claims (5)

  A cationic polymer compound in which two ink receiving layers containing inorganic fine particles and a water-soluble binder are continuously laminated on the surface of the support, and the lower ink receiving layer has a number average molecular weight of 1,000 to 50,000. And an upper ink receiving layer containing a cationic polymer compound having a number average molecular weight of 80000 or more and a cationization density of 6.5 meq / g or more.   2. The ink jet recording medium according to claim 1, wherein the cationic polymer compound has a cationization density of 2.5 to 6.5 meq / g in the lower ink receiving layer.   The lower layer and / or the upper ink receiving layer contains 2 to 20 parts by weight of the cationic polymer compound with respect to 100 parts by weight of the inorganic fine particles. Inkjet recording medium.   4. The ink jet recording medium according to claim 1, wherein the upper ink receiving layer is a cast coat treatment layer. An ink receiving layer containing inorganic fine particles and a water-soluble binder is provided on the surface of the support, and a region having a thickness of 3 to 100 μm facing the support in the ink receiving layer has a number average molecular weight of 1000 to 50000 A polymer compound is contained, and a region having a thickness of 5 to 150 μm from the outermost surface of the ink receiving layer contains a cationic polymer compound having a number average molecular weight of 80000 or more and a cationization density of 6.5 meq / g or more. An inkjet recording medium.