JP2005319593A - Inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium which can obtain excellent recording quality in the use of either of a dye ink and a pigment ink, and which is excellent in both lightfastness and gas resistance. <P>SOLUTION: In this inkjet recording medium, at least two ink absorbing layers, each containing a pigment and an adhesive, are provided on the surface of a substrate; the outermost ink absorbing layer contains a first cationic polymer with a number average molecular weight of 80,000 or more and a cationization density of 6.5 meq/g or more; the ink absorbing layer, which is a lower layer adjacent to the outermost layer, contains a second cationic polymer with a number average molecular weight of 1,000-50,000 or more; and the adhesive for the outermost layer and the lower layer contains a polyvinyl alcohol with a polymerization degree of 1,000 or more and a saponification degree of 89 mol% or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording medium used in an ink jet recording system.

The ink jet recording system is rapidly spreading because it is easy to make full color and has less printing noise. This ink jet recording system performs recording by flying and adhering ink droplets from a nozzle to a recording medium at a high speed, and contains a large amount of solvent in the ink. Therefore, the ink jet recording medium is required to have a property of quickly absorbing ink. In addition, with the recent spread of computers and digital cameras, image quality close to that of silver halide photography is also required for the ink jet recording system.
For this reason, a technique for providing an ink receiving layer having a high ink absorbability on the surface of a recording medium has been developed.

By the way, conventionally, water-based dye ink has been mainly used in the ink jet recording system. Since this water-based dye ink uses a low-molecular-weight compound dye as a colorant, it has good color developability but is inferior in water resistance and weather resistance. Therefore, in order to 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 in order to enhance color development, the colorant accumulates on the surface of the recording medium, resulting in a decrease in friction resistance, resulting in smearing of printed matter, or absorption of the solvent in the ink due to the accumulation of colorant. May interfere.
Thus, in recent years, since both dye ink and pigment ink are used for ink jet recording, a recording medium suitable for both of these inks is required. Therefore, a technique for imparting suitability to both inks using an adhesive composed of a pigment and a vinyl chloride-vinyl acetate copolymer in the ink receiving layer is also disclosed (for example, see Patent Document 4).

Furthermore, in recent years, as ink jet recorded images become higher quality, image storage stability (light resistance, gas resistance (such as ozone and NOx), plasticizer resistance, etc.) has become important. In order to meet this demand, in addition to improving the ink itself, technologies that contain various compounds in the ink receiving layer have been developed.
For example, a technique is disclosed in which a thiourea derivative is included in a porous ink receiving layer to prevent fading during long-term storage after printing (see, for example, Patent Document 5). Moreover, the technique which uses the acidic paper containing antioxidant for a support body is disclosed (for example, refer patent document 6). According to this technique, it is possible to prevent yellowing of the white paper portion during long-term storage and improve light resistance.

JP-A-11-20306 JP 2000-79752 A JP 2003-145916 A JP 2001-270238 A Japanese Patent Laid-Open No. 8-25796 JP 2000-177241 A

However, in the case of the technique described in Patent Document 4, the storability of the image has not been studied at all.
In the case of the technique described in Patent Document 5, there is a difficulty in terms of safety of the compound (thiourea derivative) contained in the ink receiving layer. Furthermore, in the case of the technique described in Patent Document 6, the light resistance of an image can be improved, but it is difficult to improve the gas resistance. The reason for this is that light does not reach the inside of the recording medium, so that the light resistance is affected by the reaction near the surface of the recording medium, but gas (ozone, NOx, etc.) permeates into the recording medium and is gas resistant. This is considered to be because the property is influenced by the reaction of the entire recording medium.
Accordingly, an object of the present invention is to provide an ink jet recording medium that can obtain excellent recording quality using either dye ink or pigment ink, and that is excellent in both light resistance and gas resistance. is there.

In general, it has been known that the cationic polymer compound in the ink receiving layer of the recording medium is involved in fixing the dye ink and the pigment ink in the ink jet printing. However, the difference in the coloring mechanism between the dye ink and the pigment ink is known. 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 is considered as follows. That is, the dye ink is a water-soluble anionic polymer. 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.
Therefore, the lower ink-receiving layer contains an ink-absorbing pigment and a low-molecular-weight cationic polymer compound, and the gap in the pigment in the layer is filled with the cationic polymer compound, so that the upper-layer ink-receiving layer is received. It is possible to prevent the pigment ink colorant penetrating from the 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 can contain a cationic polymer compound having a high molecular weight and 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.
It has also been found that the use of polyvinyl alcohol having a predetermined polymerization degree and saponification degree as an adhesive improves both light resistance and gas resistance.

  That is, the ink jet recording medium of the present invention comprises two or more ink receiving layers each containing a pigment and an adhesive on the support surface, the outermost ink receiving layer having a number average molecular weight of 80000 or more, a cationization density. 6.5 meq / g or more of the first cationic polymer compound, and the lower ink receiving layer adjacent to the outermost layer contains the second cationic polymer compound having a number average molecular weight of 1,000 to 50,000, Furthermore, the adhesive of the outermost layer and the lower layer contains polyvinyl alcohol having a polymerization degree of 1000 or more and a saponification degree of 89 mol% or less.

  The outermost layer and / or the lower ink receiving layer may contain 2 to 20 parts by mass of the first cationic polymer compound and / or the second cationic polymer compound with respect to 100 parts by mass of the pigment. The outermost layer and / or the lower ink receiving layer preferably contains 5 to 35 parts by mass of the polyvinyl alcohol with respect to 100 parts by mass of the pigment.

  According to the present invention, an excellent recording quality can be obtained by using either a dye ink or a pigment ink, and an ink jet recording medium excellent in both light resistance and gas resistance can be obtained.

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

  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. . In particular, a highly absorbent material such as paper or a support having a coating layer is preferable.

<Support>
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 with 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.

  The ink receiving layer in the present invention comprises two or more layers, and each layer contains a pigment and an adhesive. In the present invention, it is essential that the outermost ink-receiving layer and the lower-layer ink-receiving layer are continuously laminated. For example, another layer is provided between the lower-layer ink-receiving layer and the support. May be interposed, or another layer may be laminated on the surface of the upper ink receiving layer.

<Outermost ink receiving layer>
(Pigment)
The pigment has a function of adsorbing a dye ink colorant or pigment ink colorant and absorbing an ink solvent and serving as a carrier for other auxiliary agents. Examples of the pigment include, for example, synthetic silica, colloidal silica, colloidal alumina, gas phase method silica, gas phase method alumina, boehmite, pseudoboehmite, aluminum hydroxide, alumina, lipotone synthesized by gel method, precipitation method, dry method, etc. , Zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, aluminum silicate, diatomaceous earth, calcium silicate, kaolin, calcined kaolin, talc, clay, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin White or the like can be used. Further, one or more of the above pigments can be mixed and used.

(First cationic polymer compound)
The outermost ink receiving layer contains a first 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 is considered that the coloring property of the dye ink can be improved by allowing the ink receiving layer to contain a cationic polymer compound having a high molecular weight and a high cationization density so that the dye ink is aggregated and absorbed in the layer.
Here, when the cationization density of the cationic polymer compound is less than 6.5 meq / g, the color developability of the dye ink is particularly deteriorated. On the other hand, if the cationization density becomes too high, the fixability of the ink is improved, but the ink absorptivity may be hindered, so 12.0 meq / g or less is preferable. More preferably, the cationization density is 7.0 to 12.0 meq / g.
The number average molecular weight of the upper layer of the cationic polymer compound is 80,000 or more, preferably 100,000 to 10,000,000. When the number average molecular weight 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.

Examples of the cationic polymer compound include primary amines, secondary amines, tertiary amines, quaternary ammonium salts and cyclic amines, or polymer compounds using these salts as monomers. Specifically, vinylimine, alkylamine, alkyleneamine, vinylamine, alicyclic amine, epihalohydrin, dialkylaminoethyl methacrylate, dialkylaminoalkyl acrylate, dialkylaminoalkylacrylamide, diallyldimethylammonium salt, acrylamide, amidoamine, amidine, etc. The cationic polymer compound used as a monomer is exemplified. Also, so-called polyethyleneimine resins, polyamine resins, polyamide resins, polyamide epichlorohydrin resins, polyamine picrohydrin resins, polyamide polyamine epichlorohydrin resins, polydiallylamine resins, dicyandiamide condensates and the like can be mentioned. The above cationic polymer compound can be used alone or 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. In particular, a dialkyl (alkylene) amine epihalohydrin polymer (homopolymer), a copolymer of this compound, and a derivative of this compound are most preferred because they hardly inhibit the ink absorbability of the ink receiving layer even at a low molecular weight.
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 addition, when using what mixed multiple types of cationic polymer compounds, the number average molecular weight of a mixture and the mass average value of a cationization density need to be in the said prescription | regulation range.
The compounding amount of the cationic polymer compound is preferably 2 to 20 parts by mass, particularly 3 to 15 parts by mass with respect to 100 parts by mass of the pigment. When the amount of the cationic polymer compound is less than 2 parts by mass, the effect of improving the ink fixing ability and printing density by the cationic polymer compound is not exhibited, and when it exceeds 20 parts by mass, the ink is accepted. The ink absorbability of the layer is lowered, and this may cause unevenness and blurring of the printed image.

(adhesive)
The adhesive ensures the coating strength of the ink receiving layer and mainly contains polyvinyl alcohol (PVA) having a polymerization degree of 1000 or more and a saponification degree of 89 mol% or less. When polyvinyl alcohol in the above range is used, the light resistance and gas resistance of the recording medium are improved for unknown reasons. Here, when the polymerization degree of polyvinyl alcohol is less than 1000, the strength of the ink receiving layer is lowered, and the sheet transportability and the like are deteriorated. Further, if the degree of polymerization is too high, the stability of the coating is deteriorated and the coating suitability tends to be inferior. Therefore, the degree of polymerization is preferably 3000 or less. On the other hand, when the degree of saponification exceeds 89 mol%, no effect of improving light resistance and gas resistance is observed. Preferably, the saponification degree is 83% or less.
In addition, when using what mixed multiple types of polyvinyl alcohol, it is necessary for the polymerization average of a mixture and the mass mean value of a saponification degree to be in the said prescription | regulation range. Examples of polyvinyl alcohol include polyvinyl alcohol alone, polyvinyl alcohol such as silyl-modified polyvinyl alcohol and cation-modified polyvinyl alcohol, and modified products thereof.
Moreover, as an adhesive, things other than polyvinyl alcohol can be used in combination, but in order to obtain an effect of improving light resistance and gas resistance by polyvinyl alcohol, the ratio of polyvinyl alcohol to the entire adhesive is 50 to 100% by mass. It is preferable to make it 80 to 100 mass% especially.

Examples of adhesives that can be used in combination with polyvinyl alcohol include starches such as oxidized starch, acetylated starch, and etherified starch and derivatives thereof; proteins such as casein, gelatin, and soybean protein; polyvinylpyrrolidone, carboxymethylcellulose, and hydroxyethylcellulose. Water-soluble polymer binders such as cellulose derivatives, etc. can be used. SB latex, NB latex, acrylic latex, vinyl acetate latex, ethylene vinyl acetate latex, polyurethane, unsaturated polyester resin, and the like can also be used. The said adhesive agent can be used 1 type or in mixture of multiple types.
It is preferable that the compounding quantity of the said whole adhesive agent is 5-60 mass parts with respect to 100 mass parts of pigments. When the blending amount is less than 5 parts by mass, the strength of the coating layer surface becomes insufficient, and when it exceeds 60 parts by mass, the ink absorbability may be hindered.

<Lower ink receiving layer>
The lower ink receiving layer adjacent to the outermost layer contains a pigment, an adhesive, and a second cationic polymer compound having a number average molecular weight of 1,000 to 50,000. Since the pigment, the adhesive, and the blending amount thereof are the same as those in the outermost ink receiving layer, the description thereof is omitted.
(Second cationic polymer compound)
The number average molecular weight of the second cationic polymer compound is 1000 to 50000, preferably 2,000 to 30,000. Here, if the number average molecular weight is less than 1000, voids in the lower ink receiving layer and pores of the inorganic fine particles are overfilled with the cationic polymer compound, and the ink (solvent) absorbability deteriorates. 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.

  The cationization density of the second cationic polymer compound 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 too quickly and penetrates from the upper ink receiving layer. The colored material may penetrate into the lower ink receiving layer and color development may be deteriorated.

The number average molecular weight of each cationic polymer is a value measured by GPC (gel permeation chromatography). Further, 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.

<Operation by outermost layer and lower ink receiving layer>
As described above, in the lower ink-receiving layer, the cationic polymer compound having a relatively low molecular weight enters the pores of the layer and the pigment, thereby reducing the voids in the lower ink-receiving layer itself. The colorant component is prevented from rapidly penetrating into the lower ink-receiving layer. As a result, the colorant is held in the uppermost ink-receiving layer, and the color developability of the pigment ink or dye ink is improved. Further, since the uppermost ink receiving layer contains a cationic polymer compound having a high cationization density, the ink solvent absorbability is high and the ink coloring is clear.
Note that when only the lower ink receiving layer is formed without providing the uppermost ink receiving layer, the ink solvent absorbs poorly, so printing with dye ink causes ink overflow, blurring and unevenness of the image. It tends to occur.

<Other ink receiving layers>
Another ink receiving layer may be provided between the lower ink receiving layer and the support, or on the surface opposite to the outermost layer and the lower ink receiving layer. The pigment, adhesive, and blending amount used for this ink receiving layer are the same as those in the case of the outermost layer and the lower ink receiving layer, and thus the description thereof is omitted. In addition, various cationic polymer compounds can be used as described above. In addition, it is preferable from the point of transparency and intensity | strength to use polyvinyl alcohol as an adhesive agent.

<Formation of ink receiving layer>
Each ink receiving layer is a coating liquid containing the pigment, adhesive, cationic polymer compound, etc., for example, blade coater, air knife coater, roll coater, brush coater, kiss coater, squeeze coater, curtain coater, die coater It can form by coating using well-known coating machines, such as a bar coater, a gravure coater, and a comma coater. Further, the total amount of coating amount may preferably be 5 to 30 g / ^{m 2,} more preferably in the range of 10 to 20 g / ^{m 2.}
Alternatively, after the lower ink-receiving layer is applied, the uppermost ink-receiving layer may be applied and formed while the coated surface is wet.
Furthermore, after coating a predetermined treatment liquid on the uppermost ink-receiving layer in a wet state, the ink-receiving layer is pressure-bonded to a heated mirror-finished surface and dried to give gloss to the surface of the ink-receiving layer. A so-called cast coat may be applied. 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.

<Ink for inkjet recording>
Examples of the ink jet recording ink to which the ink jet recording medium of the present invention is applied include water-based ink compositions, oil-based ink compositions, solid ink compositions, and the like, but water-based inks 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; a pigment ink using an organic pigment such as an insoluble pigment or a lake pigment and carbon black; Can do.

When using a dye ink, those containing an anionic compound such as a water-soluble dye having an anionic group are particularly preferred. Examples of the water-soluble dye include water-soluble direct dyes having an anionic group such as a sulfone group and a carboxyl group, acidic dyes, and reactive dyes. As this water-soluble dye, one contained in a proportion of about 0.1 to 20% by mass with respect to the ink can be used.
When pigment ink is used, organic pigments such as insoluble pigments and lake pigments, carbon black, and the like can be used as colorants. 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. Further, for the purpose of removing coarse particles of the pigment dispersion, it is preferable to use a centrifugal separator or a filter.

  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 “%” represent “parts by mass” and “mass%” unless otherwise specified.

(Manufacture of support)
90 parts of hardwood bleached kraft pulp and 10% of softwood bleached kraft pulp are mixed and beaten to adjust the freeness to 370 ml, to 100 parts of pulp, 15 parts of light calcium carbonate, 0.4 parts of cationized starch, and a yield improver After adding 0.3 part and making and drying with a long paper machine, the 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 110 g / m ^2. An m ² support was produced.

(Formation of lower ink receiving layer)
Using the following coating liquid A, the coating liquid A 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 a lower ink receiving layer. .
Coating liquid A: 100 parts of synthetic amorphous silica (fine seal X-12: BET specific surface area 240 m ² / g manufactured by Tokuyama) as a pigment, 30 parts of polyvinyl alcohol (degree of polymerization 2000, degree of saponification 81 mol%) as an adhesive And 4 parts of an ethylene vinyl acetate emulsion (Sumikaflex 401 manufactured by Sumitomo Chemical Co., Ltd.) and 8 parts of a cationic polymer compound (polyamine epichlorohydrin having a number average molecular weight of 10,000) are further mixed with stirring with solidified water. An aqueous coating solution A having a partial concentration of 20% was prepared.

(Formation of the uppermost ink receiving layer)
Using the following coating liquid B, the uppermost ink-receiving layer is formed by coating the coating liquid B on the lower ink-receiving layer with a bar coater so that the dry coating amount is 8 g / m ^2. As a result, an ink jet recording medium was obtained.
Coating liquid B: In the same manner as coating liquid A except that 8 parts of polyamine epichlorohydrin having a cationization density of 7.8 meq / g was blended instead of the cationic polymer compound, the solid content A coating liquid B having a concentration of 22% was prepared.

(Manufacture of support)
A support was produced in the same manner as in Example 1 except that the amount of cationized starch added was 0.5 part.
(Formation of lower ink receiving layer)
In the coating liquid A, instead of the polyvinyl alcohol, polyvinyl alcohol having a polymerization degree of 1000 and a saponification degree of 88 mol% was used, and instead of the cationic polymer compound, 8 parts of diallyldimethylammonium salt having a number average molecular weight of 3000 were blended. Except for this, a lower ink receiving layer was formed in the same manner as in Example 1.
(Formation of the uppermost ink receiving layer)
In the coating liquid B, the uppermost layer of the top layer was completely the same as in Example 1 except that 8 parts of diallyldimethylammonium salt acrylamide having a cationization density of 6.6 meq / g was blended instead of the cationic polymer compound. An ink receiving layer was formed to obtain an ink jet recording medium.

(Manufacture of support)
A support was produced in exactly the same manner as in Example 2.
(Formation of lower ink receiving layer)
In the coating liquid A, polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 88 mol% was used instead of the polyvinyl alcohol, and 8 parts of a dicyandiamide condensate having a number average molecular weight of 30000 was blended instead of the cationic polymer compound. Except for the above, a lower ink receiving layer was formed in the same manner as in Example 1.
(Formation of the uppermost ink receiving layer)
In the coating liquid B, the uppermost ink-receiving layer was the same as in Example 1 except that 8 parts of polyallylamine having a cationization density of 11.0 meq / g was blended instead of the cationic polymer compound. To obtain an ink jet recording medium.

<Comparative Example 1>
(Manufacture of support)
A support was produced in the same manner as in Example 1 except that the amount of cationized starch added was 0.6 part.
(Formation of lower ink receiving layer)
A lower ink-receiving layer was formed in the same manner as in Example 1 except that polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98 mol% was used instead of the polyvinyl alcohol in the coating liquid A.
(Formation of the uppermost ink receiving layer)
In the coating liquid B, the top layer of the uppermost layer was exactly the same as in Example 1 except that 8 parts of polyamine epichlorohydrin having a cationization density of 7.0 meq / g was blended instead of the cationic polymer compound. An ink receiving layer was formed to obtain an ink jet recording medium.

<Comparative example 2>
(Manufacture of support)
A support was produced in the same manner as in Example 1 except that the amount of cationized starch added was 0.7 part.
(Formation of lower ink receiving layer)
In the coating liquid A, a lower ink receiving layer was formed in the same manner as in Example 1 except that 8 parts of polyamine epichlorohydrin having a number average molecular weight of 500 was blended instead of the cationic polymer compound. did.
(Formation of the uppermost ink receiving layer)
The uppermost ink receiving layer was formed in exactly the same manner as in Example 1 to obtain an ink jet recording medium.

<Comparative Example 3>
(Manufacture of support)
A support was produced in the same manner as in Example 1 except that the amount of cationized starch added was 0.8 part.
(Formation of lower ink receiving layer)
In the coating solution A, polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98 mol% is used instead of the polyvinyl alcohol, and 8 parts of polyamine epichlorohydrin having a number average molecular weight of 500 is substituted for the cationic polymer compound. Except for the above, a lower ink receiving layer was formed in the same manner as in Example 1.
(Formation of the uppermost ink receiving layer)
In the coating liquid B, instead of the cationic polymer compound, the uppermost layer was formed in the same manner as in Example 1 except that 8 parts of polyamine epichlorohydrin having a cationization density of 5.0 meq / g was blended. An ink receiving layer was formed 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 lower ink receiving layer)
A lower ink receiving layer was formed in exactly the same manner as in Example 1.
(Formation of the uppermost ink receiving layer)
In the coating liquid B, instead of the cationic polymer compound, the uppermost layer was formed in the same manner as in Example 1 except that 8 parts of polyamine epichlorohydrin having a cationization density of 5.0 meq / g was blended. An ink receiving layer was formed to obtain an ink jet recording medium.

<Evaluation>
1. Printing quality About the recording media of the above Examples and Comparative Examples, printing was performed by an ink jet printer using pigment ink and dye ink, respectively, and printing quality was evaluated by the following method.
As the ink jet printer, PX-G900 (trade name) manufactured by Seiko Epson was used in the case of pigment ink, and PM-G800 (trade name) manufactured by Seiko Epson was used in the case of dye ink.

1-1. Print density (ink color development)
Solid images of black, cyan, magenta, and yellow were prepared and printed using spreadsheet software “Excel” manufactured by Microsoft Corporation. The recording medium after printing is left in a constant temperature and humidity chamber for 24 hours, and then 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) was evaluated.
In the case of pigment ink ○: Total of four colors exceeds 6.00 Δ: Total of four colors is 5.80 to 6.00 ×: Total of four colors is less than 5.80 In the case of dye ink ○: Four colors Total exceeds 7.00. Δ: Total of four colors is 6.80 to 7.00. X: Total of four colors is less than 6.80.

1-2. Ink absorbability A solid color image of red and green was printed, and the degree of bleeding at the print boundary was visually evaluated.
○: The boundary portion is clear and no bleeding is observed. Δ: The boundary portion is slightly blurred and bleeding is observed. ×: The boundary portion is blurred and bleeding is observed.

The overall evaluation of print quality was based on the following criteria.
Overall evaluation ○: Both print density determination and ink absorbency determination are ○
Comprehensive evaluation △: Either print density determination or ink absorbency determination △
Comprehensive evaluation x: Either print density determination or ink absorbency determination is x

2. Image storability A solid color printing of magenta ink was performed on each recording medium by an ink jet printer using a dye ink (PM-970C, manufactured by Seiko Epson Corporation), and then subjected to the following light resistance and gas resistance tests. .
2-1. Light resistance A xenon meter (irradiance 65 W / m ² ) was irradiated on the printed surface of the sample for 24 hours. Then, the image density before and after irradiation is measured with a Macbeth densitometer, and the equation (1)
Image residual ratio (%) = {(image density after irradiation) / (image density before irradiation)} × 100 (1)
The residual rate of the image was obtained from the above and used as an index of light resistance. Those having a residual rate of less than 90% were evaluated as x.

2-2. Gas Resistance The sample was exposed for 5 hours in an atmosphere in which ozone was continuously generated by an ozone generator and the ozone concentration was about 10 ppm. Then, the image density before and after exposure was measured with a Macbeth densitometer, and the image residual rate was obtained from the above formula (1), which was used as an index of gas resistance (ozone). Those having a residual rate of less than 95% were evaluated as x.

  The obtained results are shown in Table 1. 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 apparent from Table 1, in the case of the ink jet recording medium of each example, the ink jet printing quality (print density, ink absorbability) is excellent regardless of whether pigment ink or dye ink is used, as well as light resistance and gas resistance. Excellent in both sex.

On the other hand, in the case of Comparative Example 1 in which polyvinyl alcohol having a saponification degree exceeding 89 mol% was used as an adhesive, both light resistance and gas resistance were lowered. In the case of Comparative Example 2 in which the number average molecular weight of the cationic polymer compound in the lower ink receiving layer was less than 1000, the printing quality (coloring property) when using the pigment ink was lowered. In the case of Comparative Example 3 in which polyvinyl alcohol having a saponification degree exceeding 89 mol% was used as the adhesive and the number average molecular weight of the cationic polymer compound in the lower ink receiving layer was less than 1000, the pigment ink was used. Print quality, light resistance, and gas resistance all decreased. In the case of Comparative Example 4 in which the cationic polymer compound of the uppermost ink receiving layer has a cationization density of less than 6.5 meq / g, the printing quality (coloring property) when using the dye ink was lowered.

Claims (3)

  Two or more ink receiving layers each containing a pigment and an adhesive are provided on the surface of the support, and the outermost ink receiving layer has a number average molecular weight of 80000 or more and a cationization density of 6.5 meq / g or more. A cationic polymer compound, and a lower ink-receiving layer adjacent to the outermost layer contains a second cationic polymer compound having a number average molecular weight of 1,000 to 50,000, and the outermost layer and the lower layer adhesive Which contains polyvinyl alcohol having a polymerization degree of 1000 or more and a saponification degree of 89 mol% or less.   The outermost layer and / or the lower ink receiving layer may contain 2 to 20 parts by mass of the first cationic polymer compound and / or the second cationic polymer compound with respect to 100 parts by mass of the pigment. The inkjet recording medium according to claim 1, wherein the inkjet recording medium is contained.   The inkjet recording according to claim 1 or 2, wherein the outermost layer and / or the lower ink receiving layer contains 5 to 35 parts by mass of the polyvinyl alcohol with respect to 100 parts by mass of the pigment. Media.