JP2007076151A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method, by which a high quality print excellent in ink absorbency in spite of having high scratching properties and high weatherability is obtained. <P>SOLUTION: In the image forming method, by which an ink jet printing is performed by injecting an ink jet ink including a latex to a void type ink jet recording medium, the void type ink jet recording medium has at least two structural layers under the condition that at least one layer between the structural layers is set to act as a cushioning layer for absorbing external pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming method in which an ink-jet ink containing latex is ejected onto a void-type ink jet recording medium by an ink jet method, and more specifically, image formation capable of obtaining a high-quality print having high scratch resistance and weather resistance. It is about the method.

Inkjet printing systems are still inferior to silver halide photography, particularly in terms of image storage and gloss. Become a particular problem in image storability, an ozone fading by ozone and NO _x in the atmosphere. As means for solving the ozone fading, for example, JP-A-63-252780, JP-A-64-11877, JP-A-1-108083, JP-A-126881, JP-A-1-218882, JP-A-1-258980, No. 2-188287, No. 7-237348, No. 7-266689, No. 8-164664, and the like. However, in order to achieve high ink absorbability corresponding to recent high-speed printers, so-called air gap type ink jet recording media are generally used as ink jet recording media. Therefore, a drastic improvement method is desired.

  On the other hand, as one means for improving the gas fading, a method of adding water-dispersible resin fine particles (hereinafter also referred to as latex or latex fine particles) to ink is known. For example, a technique for forming a gas barrier layer on an ink jet recording medium after printing by including resin fine particles or latex fine particles in the ink is disclosed (for example, see Patent Document 1). In addition, for the purpose of improving image storability or gloss, a technique for applying a colorless resin fine particle-containing liquid to a colored ink adhesion region is disclosed (for example, see Patent Documents 2 and 3). Furthermore, among the high weather resistance technologies using such resin fine particles, not only the ink technology but also a technology that exhibits a function in combination with an inkjet recording medium has been proposed. For example, resin fine particles are dispersed in a colored ink containing a water-soluble dye, and a resin barrier layer is formed after printing to suppress the entry of ozone gas and the like, and the surface pH of the void-type inkjet recording medium is 5.5 to 5.5. An ink jet recording method and a recorded product for improving ozone resistance and color developability by increasing mordant fixing power by setting to 7.5 are disclosed (for example, see Patent Document 4). In addition to forming a gas barrier layer, a technique that achieves both high ink absorptivity by controlling the particle diameter of resin fine particles in the ink and the pore diameter of the void-type inkjet recording medium is disclosed (for example, (See Patent Document 5). Furthermore, in addition to the resin fine particles contained in the colored ink, a substantially colorless ink composition (colorless ink) which does not contain a colorant is newly provided, and in particular, reverse imagewise from a white background portion to a low concentration portion. A method of forming a uniform gas barrier layer by printing colorless ink in a form that compensates for the ozone and significantly improving ozone resistance is disclosed (for example, see Patent Document 6).

  However, it has been found that the methods described in each of the above-mentioned patent documents have the following serious problems, although some effects are recognized with respect to oxidizing gas resistance.

  That is, an image formed with an inkjet ink containing latex exhibits a high gas barrier ability due to the latex film formed on the inkjet recording medium, but when an external pressure is applied to the latex film, film defects due to scratch marks or the like are present. It is easy to occur, and the outside air, for example, oxidizing gas enters from the defective part of the film, causing gas fading only around the defective part, causing density deviation or color deviation from an undamaged image part, The problem that density unevenness and color unevenness that are far larger than the appearance problem occur has become apparent. In the range where ink-jet printing is actually handled, rubbing against the back of the print or scratching with hard objects is inevitable, but if fading occurs due to the invasion of oxidizing gas from the scratch, it will be directly received. There is a need for immediate improvement because it is recognized as an image defect in excess of the size of the scratch.

In general, as a method for suppressing the scratch resistance of a formed image, for example, it is publicly used to add fine particles having a sliding effect represented by various matting agents to the outermost layer of an ink jet recording medium. The addition of a small amount of fine particles has a small effect on the scratch resistance, and when added in a large amount, there is a problem that the gloss is rapidly lowered according to the addition amount. Furthermore, in image formation using an inkjet ink containing latex, the latex film covers the surface of the inkjet recording medium. Therefore, even if the matte agent or the like is added to the inkjet recording medium as described above, the effect can be obtained. The current situation is that it cannot be fully utilized.
JP 2004-50545 A International Patent No. 00/06390 pamphlet JP 2001-39006 A JP 2005-125585 A JP 2004-50545 A JP 2005-88411 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming method capable of obtaining a high-quality print excellent in ink absorbency while having high scratch resistance and high weather resistance. . More specifically, an object of the present invention is to provide an image forming method that suppresses the invasion of an oxidizing gas from a damaged portion due to external pressure to the latex film while realizing high weather resistance by the latex film, and does not cause discoloration unevenness. .

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

  (1) In an image forming method in which an inkjet ink containing latex is ejected onto a void-type inkjet recording medium and inkjet printed, the void-type inkjet recording medium has at least two constituent layers, and at least of the constituent layers An image forming method, wherein one layer is an impact relaxation layer that absorbs external pressure.

  (2) The image forming method as described in (1) above, further comprising a high-strength layer subjected to a curing treatment at a lower portion adjacent to the impact relaxation layer.

  (3) The impact reducing layer is a layer containing silica fine particles or alumina fine particles and having a dry film thickness substantially not containing a binder of 0.1 μm or more and 3.0 μm or less (1) ) Image forming method.

  (4) The impact reducing layer is a layer containing colloidal silica or colloidal alumina and having a dry film thickness of 0.1 μm or more and 3.0 μm or less substantially free of a binder. The image forming method described in the item).

  (5) At least one of the inkjet inks containing the latex is a colorless ink substantially free of a colorant, and the other inkjet inks are colored inks containing a colorant. The image forming method according to any one of 1) to (4).

  In addition to the above configuration, more preferred embodiments are shown below.

  (6) The image forming method as described in (5) above, wherein the colorant contained in the colored ink is a water-soluble dye.

  (7) The image forming method according to any one of (1) to (6), wherein a print drying unit is provided to perform drying immediately after performing the inkjet printing.

  According to the present invention, it is possible to obtain a high-quality print excellent in ink absorbency while having high scratch resistance and high weather resistance, and further to achieve high weather resistance with the latex film, while also damaging the latex film due to external pressure. Therefore, it is possible to provide an image forming method that suppresses the intrusion of the oxidizing gas from the colorant and does not cause discoloration unevenness.

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

  As a result of intensive studies in view of the above problems, the present inventor has found that in a method of forming an ink jet by injecting an inkjet ink containing latex onto a gap type inkjet recording medium, the gap type inkjet recording medium is at least 2 The image forming method is characterized in that the ink absorbing property can be obtained while having high scratch resistance and high weather resistance, wherein the image forming method is characterized in that at least one of the constituent layers is an impact relaxation layer that absorbs external pressure. An image forming method that can produce excellent high-quality prints, and further suppresses the invasion of oxidizing gas from scratched parts due to external pressure into the latex film while realizing high weather resistance with the latex film, and does not cause discoloration unevenness. As a result, the present invention has been found.

  Details of the image forming method of the present invention will be described below.

  First, the structure of the void-type inkjet recording medium according to the present invention will be described.

(Shock mitigation layer)
A void-type ink jet recording medium according to the present invention (hereinafter also simply referred to as a recording medium) has at least two constituent layers, and at least one of the constituent layers is an impact relaxation layer that absorbs external pressure. And

  The impact relieving layer as used in the present invention is a dry scratch test of a recording medium in an unprinted state (using a scratch strength meter Haydon-18 manufactured by Haydon Co., Ltd.) and changing the load by 0 to 100 g with a 0.2 mmΦ sapphire needle. The measurement conditions were carried out in an environment of 25 ° C. and 55% RH at a moving speed of 10 mm / sec.), And the load clearly recognized as a flaw was 1 to 15 g. Although the details are not clear, it is considered that the layer has a characteristic that the repulsive force due to the external pressure is low, and the fine particles which are constituent factors relatively easily move with respect to the load.

  As long as the structure of the impact relaxation layer has the above-mentioned characteristics, the object and effect of the present invention can be obtained. However, as a preferred form of the impact relaxation layer, a structure consisting of a fine particle layer substantially containing no binder is used. Can be mentioned.

  The term “substantially free of binder” as used in the present invention means that the structure does not hinder the movement of fine particles due to external pressure due to adhesion between the particles. For the purpose, the effect of the present invention can be obtained even if a small amount of binder or the like is added to obtain a weak interparticle interaction. Further, since the impact relaxation layer does not substantially contain a binder, the binder does not swell due to ink absorption, and the ink absorption is not hindered.

  The impact relaxation layer may be disposed at any position in the air gap type ink jet recording medium having a laminated structure, but in order to disperse the external pressure efficiently, it should be the outermost layer disposed at the position farthest from the support. desirable. Moreover, although the impact relaxation ability is efficiently expressed in the dry film thickness range of 0.1 to 3.0 μm, it is more preferably 0.3 to 2.0 μm from the viewpoint of both scratch resistance and high color developability, More preferably, it is 0.4-2.0 micrometers.

  The impact relaxation layer is composed mainly of fine particles containing substantially no binder, but the fine particles to be applied are preferably vapor phase silica or alumina fine particles having an average primary particle size of 50 nm or less. More preferably, the average particle size of the primary particles is 20 nm or less, and in particular, fine particles having an average particle size of the primary particles of 2 to 20 nm are preferable from the viewpoint of exhibiting all the object effects of the present invention.

Solid content of the inorganic fine particles in the impact absorbing layer according to the present invention, 0.01 g / m ² or more, it is preferable to use the 3.0 g / m ² or less, 2.6 g / m ² or less is more preferred.

When the solid content of the inorganic fine particles exceeds 3.0 g / m ² , overflow due to a decrease in ink absorption rate and a decrease in the maximum density occur, making it impossible to obtain a high-quality image. Further, if the solid content of the inorganic fine particles is less than 0.01 g / m ² , the effect of the present invention cannot be obtained.

  Further, in the impact relaxation layer according to the present invention, it is preferable to use colloidal silica or colloidal alumina having an average primary particle diameter of 10 to 200 nm as fine particles in place of the vapor phase silica or alumina fine particles. More preferable from the viewpoint of absorbability.

When using loyal silica or colloidal alumina as the inorganic fine particles, the solid content is preferably 0.01 g / m ² or more and 2.0 g / m ² or less. When the solid content of colloidal silica or colloidal alumina exceeds 2.0 g / m ₂ , overflow due to a decrease in ink absorption speed and a decrease in maximum density occur, and a high-quality image cannot be obtained. Further, when the solid content of the inorganic fine particles is less than 0.01 g / m ₂ , the effect of the present invention cannot be obtained.

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

  The fine particles described above constituting the impact relaxation layer according to the present invention are preferably inorganic fine particles, such as light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate. , Titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina hydrate, colloidal alumina, Examples thereof include white inorganic pigments such as pseudo boehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide. Among them, alumina hydrate, cationic colloidal silica, anionic colloidal silica (hereinafter collectively referred to as “aluminum hydrate”, cationic colloidal silica) Called colloidal silica) From the viewpoint of more exhibit the targeted effects of the invention.

  As the shape of the inorganic fine particles, spherical fine particles are generally used. However, in the present invention, fine particles such as a pearl necklace shape in which spherical fine particles are connected may be used.

  The inorganic fine particles used in the impact relaxation layer according to the present invention may be used as primary particles or in a state where secondary aggregated particles are formed.

  The impact relaxation layer according to the present invention is obtained by coating an aqueous coating solution mainly containing inorganic fine particles on a porous ink absorbing layer under a wet film thickness condition for achieving a dry film thickness defined in the present invention. As a coating method applied at that time, a conventionally known coating method can be applied, for example, gravure coating method, roll coating method, rod bar coating method, air knife coating method, extrusion The coating method, the curtain coating method, or the extrusion coating method using a hopper described in US Pat. No. 2,681,294 can be used, but the impact relaxation layer can be formed uniformly and with high accuracy. From the viewpoint, a slot nozzle spray coating apparatus can be preferably applied.

  Hereinafter, a slot nozzle spray coating apparatus preferably used for forming the impact relaxation layer according to the present invention will be described.

  In the formation of the impact relaxation layer according to the present invention, the substrate to be coated with the porous ink absorbing layer coated on the support is moved (conveyed) relative to the coating liquid nozzle of the coating apparatus, and continuously. The impact relaxation layer is formed. The coating liquid (impact mitigating layer coating liquid) nozzle of the coating apparatus is at least the coating width of the coated body (refers to the length of the coated portion of the coated body in the direction intersecting the transport direction of the coated body) The coating liquid is applied onto the coated body simply by transporting the coated body to the coating device by arranging the length to correspond to the transport direction of the coated body. When the object to be coated is a long belt-like support, the belt-like support itself is transported in the longitudinal direction of the belt-like support, and the coating liquid nozzle of the coating device is moved in the width direction of the belt-like support (perpendicular to the longitudinal direction). Preferably in the direction of An extremely thin coating film can be applied with high film thickness uniformity without a drying load by conveying the object to be coated in one direction to the coating apparatus and spraying the coating liquid as droplets over the coating width.

In addition, the droplets of the impact relaxation layer forming liquid sprayed from the coating liquid nozzle of the coating apparatus are in the coating width direction,
1: the droplet size distribution is uniform,
2: The area range in which the droplets fall on the coated body has a uniform drop length in the transport direction,
3: The angle falling on the coated body is uniform,
4: The collision speed falling on the coated body is uniform,
By this, it becomes possible to ensure the uniformity of the coating film thickness.

  That the droplet diameter distribution is uniform in the coating width direction specifically means that the variation of the average droplet diameter is ± 20% or less in the coating width direction. More preferably, it is ± 10% or less.

  In addition, that the length in the transport direction of the area range in which the droplets fall on the coated body is uniform means that the variation in the length in the coating width direction is ± 10% or less. More preferably, it is ± 5% or less.

  Further, the spread angle of the liquid droplets falling on the coated body is uniform, the fluctuation of the falling angle of the liquid droplets falling on the coated body in the coating width direction with the coating liquid nozzle of the coating device as a base point, It means ± 10% or less. More preferably, it is ± 5% or less.

  Further, that the spatial density of the droplet group falling on the coated body is uniform means that the variation in the spatial density of the droplet group falling on the coated body in the coating width direction is ± 10% or less. To tell. More preferably, it is ± 5% or less.

  In order to achieve a uniform spray as described above, it is particularly preferable to use a slot nozzle spray device in the present invention.

  The slot nozzle spray device has a plurality of coating liquid nozzle holes for discharging the coating liquid in the coating width direction. The coating solution nozzle holes may be arranged in a line in the coating width direction or in a staggered manner. And a gas nozzle hole for ejecting gas in the vicinity of the coating liquid nozzle hole, and a mechanism for colliding the gas ejected from the nozzle with the coating liquid ejected from the coating liquid nozzle hole to form a droplet. Have.

  As a slot nozzle spray device that can be preferably used in the present invention, for example, a device described in JP-A-6-170308 can be applied. Japanese Patent Laid-Open No. 6-170308 discloses an example in which an adhesive for disposable diapers is applied onto a fiber using this slot nozzle spray device. However, an extremely high viscosity coating liquid (adhesive) is applied to the slot nozzle. It is dropped in a fiber form from a coating liquid nozzle (coating liquid discharge portion) of the spray device, and the coating apparatus and the object to be coated (fiber) are connected by the fiber-shaped coating liquid. That is, unlike the manufacturing method of the present invention, it is not applied as a discontinuous droplet on the object to be coated. The fiber-like coating liquid falling in parallel from each of the plurality of coating liquid nozzles provided over the coating width is disturbed by the gas ejected from the gas nozzle provided in the vicinity of the coating liquid nozzle, preventing vertical drop. And only land randomly within a certain area on the coated body. Without the gas nozzle, the fiber-like coating liquid falls vertically as it is, but by ejecting the gas from the gas nozzle, it is possible to disperse and land the coating liquid over a wider range. The coating layer is simply spread and placed, and is not a coating that requires strictly uniform coating film thickness over the entire surface of the coated body as described in the example of the ink jet recording medium. Further, since the adhesive is applied, the formed coating film is extremely thick.

  Further, a slot nozzle spray coating apparatus disclosed in JP-A-5-309310 can also be preferably used in the present invention. In the example disclosed in Japanese Patent Laid-Open No. 5-309310, a hot melt type adhesive is applied onto an object to be coated, as in the above-mentioned Japanese Patent Laid-Open No. 6-170308. Since this is also a very high viscosity coating liquid (adhesive), it is a method of continuously discharging the coating liquid to the surface of the coated body in the form of fibers, and there is no strict film thickness uniformity. The coating film to be formed is also very thick.

  In the present invention, the slot nozzle spray coating apparatus described in JP-A No. 2004-106378 can be preferably used particularly from the viewpoints of coating uniformity and coating ease.

  Next, a specific form of the slot nozzle spray coating apparatus used in the coating apparatus according to the present invention will be described.

  FIG. 1 is a schematic view for explaining the production method of the present invention. In the figure, reference numeral 1 is a slot nozzle spray portion of a slot nozzle spray device (the whole is not shown), and 9 is a long belt-like support-type coated body.

  The coated body 9 is transported at a constant speed by a transport means (not shown) in the transport direction indicated by the arrow in the drawing, which is the longitudinal direction of the coated body 9. The coating liquid nozzle C of the slot nozzle spray unit 1 has a length in the width direction of the object 9 to be applied, which is a direction orthogonal to the transport direction, and is disposed so as to face the application surface of the object 9 to be applied. Yes. From the coating liquid nozzle C, the impact relaxation layer coating liquid is sprayed in the form of droplets, and the coating is performed by landing the droplets on the object 9 to be transported. At this time, the length to which the impact relaxation layer coating solution in the width direction of the substrate 9 is attached corresponds to the coating width indicated by the arrow in the figure. In FIG. 1, the application width is shorter than the length in the width direction of the article 9 to be applied, but it may of course be the same.

  FIG. 2 is a schematic cross-sectional view showing an example of a slot nozzle spray device including the slot nozzle spray unit described in FIG.

  The slot nozzle spray unit 1 includes a pair of internal die blocks 3a and 3b and external die blocks 2a and 2b on the outside of the pair of internal die blocks 3a and 3b. The coating liquid nozzle C is formed in the gas nozzle D between the internal die block 3a and the external die block 2a, and between the internal die block 3b and the external die block 2b.

In FIG. 2, the slot nozzle spray unit 1 has a pair of gas nozzles D having a gas pocket A and a coating liquid nozzle C having a coating liquid pocket B. The impact relaxation layer coating liquid has a viscosity (preferably 0.1 to 250 mPa · s) that can form droplets without forming a fiber, and a coating liquid such as a function-imparting compound-containing solution is placed in the preparation kettle 4 and the pump 5 Through the flow meter 6, the liquid is supplied to the coating liquid pocket B and guided to the coating liquid nozzle 3. On the other hand, pressurized air is supplied from the pressurized air source 7 to the gas pocket A via the valve 8 to the gas nozzle 2.
At the time of application, the application liquid is supplied from the preparation kettle 4 so that the specified application amount is applied from the application liquid nozzle C, and at the same time, pressurized air is sprayed from the pair of gas nozzles D to form the application liquid in the form of droplets. It is sprayed and deposited on the body 9. In the production method of the present invention, the impact relaxation layer coating liquid can be sprayed as fine droplets instead of in the form of fibers. By supplying the impact relaxation layer coating liquid as fine droplets onto the surface of the object 9 to be coated, a highly uniform thin film can be formed at high speed without a drying load.

  FIG. 3 shows an example of a coating production line in which the slot nozzle spray device as described above is arranged. Here, as the coated body, a substrate in which an ink absorbing layer is coated is used. After applying the ink absorbing layer, a plurality of (multi-stage) slot nozzle spray devices were arranged in the drying process. In this way, on the same line, the formation of the ink absorbing layer and the application of the impact relaxation layer (outermost layer) according to the present invention are called online coating.

  A porous material supplied from the flow-regulating slide bead coating device 20 in the process of passing the support roller 21 from the original winding of the support by a transport means (not shown) and further reversely transporting at the position of the backup roll 22. A coating solution for the quality ink absorbing layer is applied. Since the coating liquid for the porous ink absorbing layer contains a hydrophilic binder, it is cooled once in the cooling zone 30 and fixed. The substrate 9 having the ink absorption layer on the support is conveyed to the drying process. In the drying process, a reverser 23 that blows air and reversely conveys the coating film surface in a non-contact manner and a normal conveyance roller 24 that reversely conveys the reverse surface of the coated object 9 are provided alternately. Is meandering. In this drying step, hot air is blown to dry (the hot air blowing means is not shown). Application by droplet spraying as described above is performed by the two slot nozzle spray devices 1 in the middle of this drying process, preferably at a position after the reduced rate drying. Of the two slot nozzle sprays, at least one is preferably placed at a position after the drying end point from the viewpoint of drying properties. In this example, two slot nozzle spray devices are used, but one or of course three or more nozzles may be used.

(High strength layer)
Next, in the ink jet recording medium according to the present invention, the high-strength layer provided in the lower part in the state adjacent to the above-described impact relaxation layer will be described.

  As described above, the high-strength layer in the present invention refers to a layer characterized in that a load that is clearly recognized as a flaw in the dry scratch test is 35 g or more. The void-type ink absorbing layer originally has a high repulsive force against external pressure, and not only is scratched at a certain load or more, but also the void portion is crushed and cracks are generated up to the interface with the support. On the other hand, the high-strength layer subjected to the curing treatment according to the present invention can suppress the generation of scratches against a higher load. However, if the ink absorbing layer is composed of only the high-strength layer, the tolerable external pressure will be low, so it is important to place an impact relief layer adjacent to this high-strength layer adjacent to the high-strength layer so as to efficiently receive the external pressure It is.

  As means for realizing the high-strength layer, it is possible to use a combination of known techniques. For example, as described in Japanese Patent Application Laid-Open No. 2001-253161, a method of curing the voids by promoting the crosslinking of the hydrophilic binder by overcoating isocyanate as a solvent from the surface of the ink jet recording medium, No. 278100, a method of increasing the film strength by heat treatment at a high temperature using a highly saponified polyvinyl alcohol, and a method described in Japanese Patent Application Laid-Open No. 2005-131802. By using a polyvalent metal complex such as zirconyl and a water-based epoxy resin in combination, a method of performing a curing treatment due to a swelling suppression effect by crosslinking can be exemplified.

  These known curing treatments generally have an effect of preventing softening by suppressing swelling, but the strength is increased by a strong crosslinked structure even in a dry state. In addition, it has the effect of greatly improving ink absorbency by suppressing swelling.

[Other components of inkjet recording medium]
The ink jet recording medium according to the present invention is a recording material suitable for the ink jet recording method, and preferably has a porous ink absorbing layer on at least one surface on a non-water-absorbing support.

  Examples of the non-water-absorbing support that can be preferably used in the present invention include a transparent support and an opaque support.

  Examples of the transparent support include films having materials such as polyester resins, diacetate resins, triatesate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, and celluloid. Among them, those having a characteristic to withstand radiant heat when used for overhead projectors are preferable, and polyethylene terephthalate is particularly preferable from such a viewpoint. The thickness of such a transparent support is preferably 50 μm to 200 μm.

  On the other hand, as the opaque support, for example, resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which a white pigment or the like is added to at least one of the base paper, polyolefin (polyethylene, polypropylene, etc.), polyethylene terephthalate, barium sulfate Further, an opaque resin film to which a white pigment such as titanium oxide is added, or a composite film support obtained by bonding two or more of them can be used.

  The thickness of these various opaque supports can vary widely depending on their use, but is generally in the range of 60 to 300 μm.

  Prior to the application of the ink absorbing layer, the surface of the support is subjected to corona discharge treatment, gelatin, other hydrophilic polymer or hydrophobic, for the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer provided thereon. It is preferable to perform a subbing treatment with a polymer. Furthermore, the ink jet recording medium according to the present invention is not necessarily transparent or white, and may be a colored recording sheet.

  As the non-water-absorbing support used in the ink jet recording medium according to the present invention, it is possible to use a paper support in which both sides of a base paper support are laminated with polyethylene. This is particularly preferable because a quality image can be obtained.

  A paper support laminated with polyethylene suitable for the present invention will be described below.

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

  The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

  In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc, and titanium oxide, paper strength enhancers such as starch, polyacrylamide, and polyvinyl alcohol, and fluorescent whitening, as necessary. An agent, a moisture retaining agent such as polyethylene glycol, a dispersant, a softening agent such as quaternary ammonium, and the like can be appropriately added.

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

  The basis weight of the base paper is preferably 40 to 250 g, particularly preferably 60 to 220 g. The thickness of the base paper is preferably 40 to 250 μm.

The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / cm ³ (JIS-P-8118). Furthermore, the base paper stiffness is preferably 20 to 200 g under the conditions specified in JIS-P-8143.

  A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the sizing agent that can be added to the base paper can be used.

  The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method defined in JIS-P-8113.

  The polyethylene that covers the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) or high-density polyethylene (HDPE), but some other linear low-density polyethylene (LLDPE) or polypropylene can also be used. .

  In particular, the polyethylene layer on the side on which the ink absorbing layer is provided has improved opacity and whiteness by adding rutile or anatase titanium oxide to the polyethylene as is widely done in photographic paper. Is preferred. The content of titanium oxide is usually 3% by mass to 20% by mass, preferably 4% by mass to 13% by mass with respect to polyethylene.

  As the polyethylene-coated paper, a paper that has been subjected to a fine-roughened surface for improving the adhesion to the ink absorbing layer and the coating property can also be used. In this case, it is preferable to perform the fine rough surface in the range of about 0.10 to 0.25 μm as the surface roughness Ra. In the polyethylene-coated paper, it is particularly preferable that the moisture content of the base paper is maintained at 3% by mass to 10% by mass.

  The stiffness of these non-water-absorbing supports mainly depends on the thickness of the base paper, and the desired stiffness can be obtained by appropriately selecting the thickness of the base paper.

  The curl of the support is an important characteristic for determining the curl characteristics provided with the ink absorbing layer, and achieves the optimal curl balance in combination with the ink absorbing layer, but the ink absorbing layer is porous. The recording medium according to the present invention, which is a quality ink absorbing layer, is generally designed to have a negative curl (a curl that raises its four corners when left on a horizontal board with the ink-absorbing layer-coated side underneath). It is preferable. The curl design of the base paper is determined by the relationship with the ink absorbing layer. However, when the A4 size base paper is left to stand for 1 hour at a temperature of 23 ° C and a relative humidity of 20 to 80%, the average height of the four corners is calculated. A range of −5 to −50 mm is preferable.

  Next, the porous ink absorbing layer provided on the non-water-absorbing support will be described.

  The ink absorbing layer may be on only one side of the support or on both sides. When providing on both surfaces, each may have the same structure and thickness, or may differ. The ink absorption layer may be a single layer or may be composed of a plurality of layers.

  The porous ink absorbing layer provided in the ink jet recording medium according to the present invention preferably contains mainly a hydrophilic binder and inorganic fine particles.

  Inorganic fine particles include, for example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite White inorganic fine particles such as aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide it can. The inorganic fine particles can be used as primary particles or in a state where secondary agglomerated particles are formed.

  In the present invention, from the viewpoint of obtaining a high-quality print with an ink jet recording medium, silica-based fine particles are used as inorganic fine particles from the viewpoint that a low refractive index and an average particle size of about 0.1 μm or less can be obtained relatively inexpensively. Alternatively, alumina-based fine particles are preferable, and alumina, pseudoboehmite, colloidal silica, fine particle silica synthesized by a gas phase method, and the like are preferable, and fine particle silica synthesized by a gas phase method is particularly preferable. The silica synthesized by this vapor phase method may have a surface modified with aluminum. The aluminum content of vapor-phase process silica whose surface is modified with aluminum is preferably 0.05 to 5% by mass with respect to silica.

  The average particle size of the primary particles of the inorganic fine particles is preferably 200 nm or less, and particularly preferably 100 nm or less from the viewpoint of glossiness and color density. The lower limit of the average particle diameter is not particularly limited, but is preferably approximately 10 nm or more from the viewpoint of production of inorganic fine particles.

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

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

  In the case where the inorganic fine particles are secondary or higher-order aggregate particles, the average primary particle size is equal to or less than the average particle size observed in the porous film, and the primary particle size of the inorganic fine particles is 50 nm or less. Are preferable, more preferably 30 nm or less, and most preferably 4 to 20 nm.

As content of the said inorganic fine particle in the water-soluble coating liquid for ink absorption layer formation, it is about 5-40 mass% in general, and it is preferable that it is 7-30 mass%. The inorganic fine particles need to form a porous ink absorbing layer having sufficient ink absorptivity and less cracking of the film, and the amount of the ink in the ink absorbing layer is 5 to 50 g / m ² . Is more preferable, and 10 to 30 g / m ² is more preferable.

  There is no restriction | limiting in particular as a hydrophilic binder which a porous ink absorption layer contains, A conventionally well-known hydrophilic binder can be used, for example, gelatin, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, polyvinyl alcohol etc. are used. However, from the viewpoint of comparatively low moisture absorption characteristics of the binder, less curling of the recording medium, and high binder ability of inorganic fine particles with a small amount of use, polyvinyl alcohol is excellent in cracking and film forming properties. Particularly preferred.

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

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

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

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

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

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

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

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

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

  In addition to inorganic fine particles and binders, various additives can be used for the porous ink absorption layer. Among them, cationic polymers, crosslinking agents, and polyvalent metal compounds improve ink absorption and bleeding with respect to dye ink. Play an important role in terms.

  In the case where the colorant contained in the colored ink in the ink composition is a water-soluble dye, a cationic polymer is preferably used for the purpose of preventing image blurring during storage after recording.

Examples of cationic polymers include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylene polyamine condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin-dialkylamine addition polymer, diallyldimethylammonium chloride Polymer, diallyldimethylammonium chloride / SO ₂ copolymer, polyvinyl imidazole, vinyl pyrrolidone / vinyl imidazole copolymer, polyvinyl pyridine, polyamidine, chitosan, cationized starch, vinyl benzyl trimethyl ammonium chloride polymer, (2-methacryloyl) Oxyethyl) trimethylammonium chloride polymer, dimethylaminoethyl methacrylate Over preparative polymer, and the like.

  Examples include the cationic polymers described in Chemical Industry Times, August 15 and 25, 1998, and polymer dye fixing agents described in “Introduction to Polymer Drugs” issued by Sanyo Chemical Industries, Ltd.

  Moreover, it is preferable that the porous ink absorption layer which concerns on this invention contains the compound whose molecular weight represented by following General formula (1) is 200 or less.

In the general formula (1), R ₁ represents a hydrogen atom, a substituted or unsubstituted alkyl group, an alkenyl group, an aryl group, an acyl group, a heteroaryl group, a heterocyclic group, NR ₄ R ₅ , or OR ₆ . R _{2 to} R ₆ each have the same meaning as R ₁ . R ₁ and R ₂ , R ₁ and R ₃ may be bonded to each other to form a ring. X represents an oxygen atom or NH.

In the general formula (1), R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group (for example, a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a hexyl group, a dodecyl group, a cycloalkyl group, etc.), A substituted or unsubstituted alkenyl group (eg, propenyl group, butenyl group, nonenyl group), a substituted or unsubstituted aryl group (eg, phenyl group), a substituted or unsubstituted acyl group (eg, acetyl group, propionyl) Group, butanoyl group, hexanoyl group, cyclohexanoyl group, benzoyl group, pyridinoyl group, etc.), substituted or unsubstituted heteroaryl group (eg triazole group, imidazole group, pyridine group, furan group, thiophene group, etc.), substituted Or an unsubstituted heterocyclic group (eg, pyridyl group, thiazolyl group, oxazolyl group) Imidazolyl group, a furyl group, a pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group, selenazolyl group, Surihoraniru group, a piperidinyl group, a pyrazolyl group, etc. tetrazolyl group), represents a NR ₄ R ₅ or OR _6,. R ₁ and R ₂ , R ₁ and R ₃ may be bonded to each other to form a ring. X represents an oxygen atom or NH.

  In the present invention, the compound represented by the general formula (1) preferably does not have an alcoholic hydroxyl group from the viewpoint of exhibiting the object effect of the present invention.

  In the general formula (1), the molecular weight is preferably 200 or less, the number of atoms excluding hydrogen atoms is preferably 15 or less, and water-soluble is preferable from the viewpoint of easy addition.

  Although the example of a compound represented by General formula (1) based on this invention is enumerated below, this invention is not limited only to these.

  The compound represented by the general formula (1) according to the present invention can be easily synthesized by a person skilled in the art according to a known method, or can be obtained as a commercial product.

  In the ink jet recording paper of the present invention, among the compounds represented by the general formula (1), urea or a derivative thereof is preferable, and among them, urea is particularly preferable.

  The ink absorbing layer provided in the ink jet recording medium according to the present invention preferably contains a polyvalent metal ion in order to improve the water resistance and moisture resistance of the formed image.

  The polyvalent metal ion is not particularly limited as long as it is a divalent or higher-valent metal ion, but preferable polyvalent metal ions include aluminum ions, zirconium ions, titanium ions, and the like.

  These polyvalent metal ions can be contained in the ink absorbing layer in the form of a water-soluble or water-insoluble salt. Specific examples of the salt containing aluminum ions include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, basic aluminum chloride (for example, polyaluminum chloride), and tetrachloroaluminate (for example, sodium). Salt), aluminum bromide, tetrabromoaluminate (eg potassium salt), aluminum iodide, aluminate (eg sodium salt, potassium salt, calcium salt), aluminum chlorate, aluminum perchlorate, thiocyanic acid Aluminum, aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum phosphate, aluminum nitrate, hydrogen phosphate Aluminum, Aluminum carbonate, Aluminum polysulfate silicate, Aluminum formate, Aluminum acetate, Aluminum lactate, Aluminum oxalate, Aluminum isopropylate, Aluminum butyrate, Ethyl acetate Aluminum diisopropylate, Aluminum tris (acetylacetonate), Aluminum tris (ethylacetate) Acetate), aluminum monoacetylacetonate bis (ethylacetoacetonate) and the like.

  Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate, and basic aluminum sulfate silicate are preferable, and basic aluminum chloride and basic aluminum sulfate are most preferable.

  Specific examples of the salt containing zirconium ions include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconium salt (for example, potassium salt), heptafluorozirconium salt (for example, sodium salt). Potassium salts and ammonium salts), octafluorozirconium salts (for example, lithium salts), zirconium fluoride oxide, zirconium dichloride, zirconium trichloride, zirconium tetrachloride, hexachlorozirconium salts (for example, sodium salts and potassium salts) , Zirconium oxychloride (zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide oxide, zirconium triiodide, zirconium tetraiodide, zirconium peroxide, zirconium hydroxide, sulfide Luconium, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, zirconium potassium sulfate, zirconium selenate, zirconium nitrate, zirconyl nitrate, zirconium phosphate, zirconyl carbonate, zirconyl carbonate Ammonium, zirconium acetate, zirconyl acetate, zirconyl ammonium acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, zirconium acetylacetonate, acetylacetone zirconium butyrate, stearin Zirconate butyrate, zirconium acetate, bis (acetylacetonato) dichroic acid Zirconium tris (acetylacetonato) chloro zirconium, and the like.

  Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl chloride, zirconyl lactate, zirconyl citrate are preferable, and zirconyl carbonate is particularly preferable, in terms of further prominently preventing bleeding after printing. Ammonium, zirconyl chloride and zirconyl acetate are preferred.

  These polyvalent metal ions may be used alone or in combination of two or more different kinds. The compound containing a polyvalent metal ion may be added to the coating solution for forming the ink absorption layer, or after the porous layer is applied, the porous ink absorption layer is once dried and over the ink absorption layer. You may supply by the coating method. When adding a compound containing polyvalent metal ions to the coating solution for forming the ink absorbing layer as in the former, a method of uniformly dissolving in water, an organic solvent or a mixed solvent thereof, or wet grinding such as a sand mill A method of dispersing and adding to fine particles by a method such as a method or emulsification dispersion can be used. When the ink absorbing layer is composed of a plurality of layers, only one layer may be added, or it may be added to the coating liquid of two or more layers or all the constituent layers. In addition, when the porous ink absorbing layer is once formed as in the latter and then added by the overcoat method, the compound containing polyvalent metal ions is uniformly dissolved in a solvent and then supplied to the ink absorbing layer. Is preferred.

These polyvalent metal ions are generally used in an amount of 0.05 to 20 mmol, preferably 0.1 to 10 mmol, per 1 m ² of the recording medium.

  In the ink jet recording medium according to the present invention, it is preferable to add a hardener of a water-soluble binder that forms a porous ink absorbing layer.

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

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

  Boric acid having a boron atom and a salt thereof as a curing agent may be used alone or in combination of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

  The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, respectively, but by mixing them both can be made into a concentrated aqueous solution and the ink absorbing layer coating solution can be concentrated. . Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.

  The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder.

  Various additives other than those described above can be added to the porous ink absorbing layer according to the present invention. For example, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene , Polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, organic resin fine particles such as urea resin or melamine resin, various surfactants of cation or nonion, JP-A-57-74193, and 57-87988 And UV absorbers described in JP-A Nos. 62-261476, JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61465991, JP-A-1-95091 and JP-A-3-13376. Anti-fading agents described in JP-A Nos. 59-42993 and 59-52689 PH of optical brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. described in JP-A-62-280069, JP-A-61-228771 and JP-A-4-219266 Various known additives such as a regulator, an antifoaming agent, a preservative, a thickening agent, an antistatic agent, and a matting agent may be contained.

  As described above, the present invention is characterized in that the difference between the pH of the ink composition and the film surface pH of the ink jet recording medium is less than 4.0.

  The film surface pH on the ink absorbing layer coating surface side of the ink jet recording medium is preferably 2.5 to 7.0, and particularly preferably 4.0 to 6.5. In the present invention, by setting the difference from the pH of the ink composition to 4.0 or less, the pH fluctuation at the time of ink landing is minimized, thereby causing poor aggregation of resin fine particles in the ink and colorant. It is preferable because generation of materials can be suppressed and an image excellent in glossiness and color development can be formed.

  In the present invention, the film surface pH is measured using a commercially available surface pH electrode at room temperature by dropping 20-50 μl of pure water onto the surface of the ink-jet recording medium on the ink absorption layer coating surface side with a microsyringe or the like. It is the value.

In the present invention, in order to make the difference between the pH of the ink composition and the film surface pH of the ink jet recording medium less than 4.0, as a method of adjusting the film surface pH of the ink jet recording medium to a desired condition,
1) A method in which the pH of a coating solution for forming an ink absorption layer is set to a predetermined value, and a desired film surface pH is obtained after coating and drying.
2) A method of coating and drying the ink absorbing layer coating liquid, overcoating with a suitable pH adjusting liquid, and further drying to obtain a desired film surface pH.
3) A method of applying the ink absorbing layer coating liquid and drying it, and then dipping in an aqueous solution having an appropriate pH and drying to obtain a desired film surface pH;
Etc.

  Among the above methods 1) to 3), 1) is not preferable for achieving the object of the present invention because there is a concern that the cationic polymer may be deactivated by stagnation of the ink absorbing layer coating solution. . Therefore, it is preferable to select the method described in 2) and 3), and 2) is more suitable as a method for easy production.

  Adjustment of the film surface pH by overcoating with an appropriate pH solution is performed by appropriately combining various acids or alkalis. Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and organic acids such as acetic acid, citric acid, and succinic acid. Examples of the alkali include sodium hydroxide, potassium hydroxide, and calcium hydroxide. Ammonia water, potassium carbonate, sodium carbonate, trisodium phosphate, triethanolamine, and the like are used.

  In order to exhibit the effects of the present invention, it is preferable to adjust the pH. In particular, when an anionic dye is used as the colorant, the mordant used for mordanting this dye causes a decrease in the mordant power due to an increase in pH. There is a problem that image storage stability such as ink resistance under high humidity and ozone gas resistance is deteriorated.

  Next, a method for manufacturing the ink jet recording medium according to the present invention will be described.

  As a method for producing the ink jet recording medium according to the present invention, each constituent layer including the high-strength layer, the ink absorbing layer and the like according to the present invention is appropriately selected from known coating methods, either individually or simultaneously, and non-water-absorbing. It can be produced by coating on a conductive support and drying. Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or US Pat. Nos. 2,761,419 and 2,761,791. The slide bead coating method using the described hopper, the extrusion coating method and the like are preferably used.

  When the slide bead coating method is used, the viscosity of each coating solution at the time of simultaneous multilayer coating is preferably in the range of 5 to 100 mPa · s, more preferably in the range of 10 to 70 mPa · s. Moreover, when using a curtain application | coating system, the range of 5-1200 mPa * s is preferable, More preferably, it is the range of 25-500 mPa * s.

  Further, the viscosity at 15 ° C. of the coating solution is preferably 100 mPa · s or more, more preferably 100 to 30,000 mPa · s, further preferably 3,000 to 30,000 mPa · s, and most preferably 10 , 30,000 to 30,000 mPa · s.

  As a coating and drying method, the coating liquid is heated to 30 ° C. or more, and after simultaneous multi-layer coating, the temperature of the formed coating film is once cooled to 1 to 15 ° C. and dried at 10 ° C. or more. Is preferred. More preferably, the drying conditions are a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the formed coating-film uniformity.

  In addition, the present invention also includes a method in which an ink-absorbing layer described in JP-A-2004-90588 is applied and dried, and then overcoated with a water-soluble additive online before being wound up into a roll, and then dried again for production. Applicable.

  Moreover, in the manufacturing process of an inkjet recording medium, it is preferable to have an aging process which preserve | saves for 24 hours or more and 60 days or less on conditions of 35 degreeC or more and 70 degrees C or less.

  The heating condition is not particularly limited as long as it is stored at a temperature of 35 ° C. or more and 70 ° C. or less for 24 hours or more and 60 days or less, but as a preferable example, for example, at 36 ° C. for 3 days to 4 weeks, 2 days to 2 weeks at 40 ° C. or 1 to 7 days at 55 ° C. By performing this aging treatment, it is possible to promote the curing reaction of the water-soluble binder or to promote crystallization of the water-soluble binder, and as a result, it is possible to achieve preferable ink absorbability.

  In the ink jet recording medium according to the present invention, since the non-water-absorbing support is used as the support, the ink absorption capacity capable of absorbing almost all of the colored ink forming the image and the colorless ink forming the protective film is maintained. It is necessary to do. Insufficient ink absorption causes ink overflow when discharging colorless ink forming a protective film, resulting in the occurrence of glare due to dot-like thickness changes.

Therefore, although it depends on the total ink volume to be applied, the absorption capacity of the ink absorption layer is preferably approximately 20 ml / m ² or more. Although the upper limit is not particularly limited, increasing the ink absorption amount requires the provision of a thicker ink absorption layer, which not only dramatically increases problems such as curling but also increases cracks in the manufacturing stage. However, restrictions on manufacturing conditions become large, which causes a large cost. Considering such a point, the upper limit of the preferred ink absorption amount is approximately 30 ml / m ² .

  When recording an image, it is necessary to control the sum of the colored ink for forming the image and the colorless ink for forming the protective film so as to be equal to or less than the ink absorption amount of the recording medium.

  Next, the surface characteristics of the ink jet recording medium according to the present invention will be described.

  In the ink jet recording medium according to the present invention, the centerline average roughness (Ra) when measured with a reference length of 2.5 mm and a cutoff value of 0.8 mm defined in JISB-0601 on the surface of the porous ink absorbing layer. 0.08 to 0.20 μm is preferable.

When Ra on the surface of the porous ink absorbing layer is less than 0.08 μm, when a protective film having a dry solid content of 0.05 to 0.3 g / m ² is formed on a white background portion, the viewing angle caused by interference fringes It is easy to change the color of the white background due to the difference. This is because the smoothness of the surface of the ink absorbing layer is too high, and the smoothness of the interface between the protective coating layer and the surface of the ink absorbing layer is too high. It is conceivable that the point-like glare derived from the interference fringes can be suppressed by suppressing regular reflection of light by slightly roughening the surface.

  On the other hand, when Ra exceeds 0.20 μm, the spot-like glare is particularly noticeable in a high density portion, particularly in a black solid portion. Originally, if the surface quality is typed, this point is not so much of a concern, but the white background and low density areas are more glossy and have a uniform recording surface. The glare has a great influence on print quality and is not preferable.

  A preferable Ra is 0.10 to 0.18 μm.

As a method for adjusting the Ra of the ink absorbing layer surface within the above range, various methods can be appropriately selected and used. In particular,
A) Smoothness of the surface of the support medium, for example, a method of adjusting the fiber length of the pulp, a method of adjusting the pressure during calendering, or a method of adjusting the amount of the surface sizing agent,
B) A method for adjusting the thickness of the polyolefin resin covering the inner paper,
C) a method of adjusting the surface shape of the cooling roll for melting and extruding onto a polyolefin resin paper support with, for example, a mirror surface roller, a fine rough surface processing roller, a mat surface processing roller,
D) a method of adjusting the composition and thickness of the undercoat layer,
E) a method of adjusting the particle size of the inorganic fine particles contained in the surface layer of the porous ink absorbing layer,
F) A method of adding various surface modifiers to the non-mordant layer (outermost layer),
G) A method of adjusting the drying conditions after applying the porous ink absorbing layer,
H) A method in which a porous ink absorbing layer is applied and dried, and then water and other solvents are again applied and dried.
Etc.

  The Ra of the white background after providing the protective film layer with the latex-containing ink generally depends on the discharge conditions of the latex-containing ink, but is generally lower than before the protective film layer is provided, and is generally 0.05-0. 15 μm.

  Further, the 60-degree specular glossiness of the porous ink-absorbing surface according to JIS-Z8741 is generally 30 to 70%. The gloss level itself does not necessarily correspond completely to Ra, but generally the higher the Ra, the lower the gloss level.

  The glossiness of the white background portion after the protective coating layer is provided with the latex-containing ink is also changed by providing the protective coating layer in the same manner as Ra, and is usually 5 to 40% higher than before the protective coating layer is provided.

  Further, the 10-point average roughness (Rz) when measured at a reference length of 2.5 mm and a cut-off value of 0.8 mm defined in JIS-B-0601 on the surface of the porous ink absorbing layer is 0.5 to 5. The maximum waviness of the filter is 0.5 to 5 μm with a reference length of 2.5 mm, and the maximum waviness of the filter is 0.5 to 5 μm, according to JIS K7105. The C value of 60 degrees specified is preferably in the range of 30 to 90%.

  Next, an ink jet recording apparatus applicable to the image forming method of the present invention and an ink jet ink applying method according to the present invention will be described.

  In the inkjet ink containing latex according to the present invention, at least one is a colorless ink substantially free of a colorant, and the other inkjet ink is preferably a colored ink containing a colorant.

  In the image forming method of the present invention, the colorless ink applying method according to the present invention may be any method that can be selected and applied to at least a part of the image, but it is applied using an inkjet head as in the case of colored ink. The method is preferred. In the image forming method of the present invention, it is preferable to use an ink jet head provided with two or more nozzles for ejecting ink jet ink onto an ink jet recording medium.

  At this time, one or a plurality of inkjet heads for discharging colorless ink may be prepared and colorless inks having different compositions may be applied. In the image forming method of the present invention, the colorless ink is preferably applied immediately after discharging the colored ink by fixing the inkjet heads for discharging the colorless ink and the colored ink to the same carriage. This is preferable for further manifesting the effects of the present invention such as film-formability and ink absorbability and the effect of improving image clarity. After a long period of time has elapsed since the image was formed with the colored ink, the ink solvent contained in the colored ink dries, and as a result, the surface of the ink-forming film that was driven with the colored ink and the colorless ink-forming film There is a concern that a clear interface is formed. Preferably, it is preferable to perform both ejections in the same printer as described above. In particular, when the colored ink contains resin fine particles, the colorless ink is used before the resin fine particles are fused and formed. Is important from the viewpoint of ink absorbability.

The protective film formation with colorless ink is preferably performed so that the dry solid content is 0.1 to 0.6 g per m ² of the recording medium. If the dry solid content exceeds 0.3 g, the rainbow is formed on the white background. Changes in color tone. On the other hand, if it is less than 0.1 g, the formation of the film becomes insufficient, and point defects are likely to occur. As a result, the effect of improving the color fading prevention with respect to the dye ink is rapidly reduced, or the effect of improving the glossiness change and the image clarity change of the image portion is reduced in the pigment ink. The dry solid content of the film formed with a preferable colorless ink is 0.1 to 0.6 g, and it is preferable that the film thickness is 350 nm or more in combination with the color ink.

  The above-mentioned image clarity is defined by JIS-K-7105, and is a method for obtaining image clarity as an image clarity from a light intensity waveform obtained through an optical comb using an optical device. The value represents the performance of the image surface that reflects the image of the object facing the image surface, and indicates how accurately the incident image is reflected or projected on the image surface. The more accurately the reflected image is given to the incident image, the higher the image clarity and, as a result, the C value increases. The C value shows the effect of combining the specular gloss and the smoothness of the surface. The higher the reflectivity and the higher the smoothness, the larger the C value. For example, the image clarity (gloss value C value%) can be measured using a image clarity measuring instrument ICM-1DP (manufactured by Suga Test Machine Co., Ltd.) under the conditions of 60 degrees reflection and 2 mm optical comb. In the present invention, it is preferable that the image clarity C value is 70 or more in an image area of any density.

  The colorless ink application region can be applied to at least a part of the inkjet recording medium. In order to achieve the effect of the present invention, it is preferable that the colorless ink is applied to both the area where the colored ink is not applied and the area where the colored ink is applied.

Further, the application amount of clear ink, the colored inks, the component concentration of the colorless ink, the characteristics of the ink jet recording medium, but the appropriate amount of the most effective is obtained different, they are preferably applied at least 2 ml / m ² or more. However, if more colorless ink than 20 ml / m ² is applied, image quality degradation and gloss reduction are undesirable. The amount of colorless ink applied is preferably adjusted so that the total amount of colored ink and colorless ink is within a certain range for each pixel. In this case, the minimum total amount is preferably ² ml / m ² or more, more preferably 8 ml / m ² or more.

In addition, when the colored ink contains latex, the total amount of resin fine particles applied by both inks is determined for each printing region in consideration of the amount of resin fine particles contained in the colored ink and the amount of resin fine particles contained in the colorless ink. It is preferable to control. At this time, the total resin fine particle amount in each region is preferably 0.5 g / m ² or more, and more preferably 1 g / m ² .

  Next, a method for recording an image using colored ink and colorless ink on the ink jet recording medium according to the present invention will be described.

  After image recording with colored ink is performed on the ink jet recording medium according to the present invention, colorless ink is preferably ejected onto substantially the entire area of the recording medium to form a protective film on the substantially entire area of the recording medium. The method is preferred.

  Here, “a protective film is formed over substantially the entire area of the recording medium” refers to a state where it can be recognized that the protective film is formed over the entire area of the recording medium in normal observation. For example, even if the protective film is not formed in the minute range of the end portion of the recording medium, the influence on the print quality is small, and the observer recognizes that the protective film is present in the entire region. Usually, a protective film may be formed on the remaining area excluding the area of about 1 mm, preferably about 0.5 mm or less from the edge of the recording medium. As another example, an area that is not recorded with colorless ink may be cut off or covered with a frame after printing. Accordingly, it is not necessary to discharge colorless ink in an area that is not valuable as an image. In short, in a normal image print, an image recording method applied to the inkjet recording medium according to the present invention is to cover all areas of a white background area and an area where colored ink is discharged as an image. It is.

  According to the study by the present inventors, in order to form a thin and uniform protective film, the composition of the colorless ink to be applied and the application method are of course important, but the amount of the colorless ink applied is small. The uniformity of the surface of the recording medium to which the colorless ink is applied is extremely important. In other words, if there are fine point defects or cracks on the surface of the recording medium, the protective film formed on the surface will be non-uniform (thick, thin, not formed, etc.) and will appear as point defects, resulting in print quality. Cause a decline. In order to solve the above-mentioned problems, the ink jet recording medium according to the present invention is particularly preferable because it contains the compound represented by the general formula (1), whereby surface defects and cracks of the recording medium can be suppressed. Further, as an effect of adding the compound represented by the general formula (1), it is known that the ink absorbability is improved, and the amount of the ink solvent remaining on the surface of the recording medium is rapidly reduced. Subsequently, when the colorless ink is applied, a uniform protective film can be obtained without causing repelling or unevenness.

Next, the latex-containing ink according to the present invention will be described. In the inkjet image forming method of the present invention, the inkjet ink to be used is characterized by containing latex, and the inkjet ink is substantially colorless and does not contain a colorant. Colored ink containing ink and colorant.

  The latex-containing ink according to the present invention mainly contains a water-dispersible resin fine particle, a liquid medium, and, in the case of a modifier, other colorants, preferably water-dispersible resin fine particles and a water-soluble solvent. And water and a colorant as main components.

  The latex applied to the present invention (hereinafter referred to as resin fine particles) is not particularly limited as long as it exhibits the effects of the present invention. For example, a water-soluble resin or a water-insoluble resin may be used. In order to express this more effectively, a water-insoluble resin dispersed in water is preferable, and an anion-modified latex is more preferable.

  Specific examples of the resin constituting the resin fine particles include, for example, acrylonitrile, styrene, acrylates (acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, methacrylic acid, Methyl methacrylate, butyl methacrylate), vinyl acetate, butadiene, vinyl chloride, polyvinylidene chloride, silicone, urethane, olefin (ethylene, propylene), or a copolymer obtained by combining two or more of these monomers. In addition, the resin to be used is preferably less residual monomer component from the viewpoint of odor and safety, preferably 3% by mass or less, more preferably 1% by mass or less, particularly 0.1% by mass relative to the solid content mass of the polymer. The mass% or less is preferable.

  The resin fine particles according to the present invention preferably have an average particle size of 10 to 200 nm, more preferably 30 to 150 nm, and still more preferably 30 to 100 nm. If the average particle diameter of the resin fine particles is 10 nm or more, the resin fine particles do not penetrate into the void layer of the void type ink jet recording medium (hereinafter, also referred to as “ink jet recording medium” or simply “recording medium”) and are present on the surface of the void layer. Therefore, it is preferable in terms of gloss performance. Further, if the average particle diameter is 30 nm or more, it is preferable in that it does not enter the pores of the ink jet recording medium and is excellent in ink absorbability during high-speed printing. If the average particle size of the resin fine particles is 200 nm or less, the resin fine particles are small to some extent, which is advantageous in terms of leveling properties on the surface of the void layer and is preferable in terms of gloss performance.

  The average particle diameter of the resin fine particles according to the present invention can be easily measured using a commercially available particle diameter measuring apparatus using a light scattering method or a laser Doppler method, for example, Zetasizer 1000 (manufactured by Malvern). .

  In the resin fine particles according to the present invention, a glass transition temperature (Tg) of −60 to 60 ° C. can be used, but from the viewpoint of achieving both initial film formability and stability during long-term storage, −40 to 40 ° C. About 20 degreeC is preferable and it is preferable that it is the range of -30-10 degreeC from a viewpoint which can fully exhibit the objective effect of this invention.

  After the ink has landed on the ink jet recording medium, in the process of concentrating the fine resin particles, the minimum film-forming temperature (hereinafter sometimes referred to as MFT) is generally considered as a property that contributes to the film strength after film formation. ) Is preferably as low as possible, and as the difference between the drying temperature at the time of film formation and the minimum film-forming temperature is large, the film performance is preferably high. In the resin fine particles according to the present invention, MFT is used as long as it is −60 to 30 ° C., but −40 to 10 ° C. is preferable, and −30 to 0 ° C. is a film formability and long-term storage stability of the formed protective film. More preferable from the viewpoint.

  MFT is a parameter that depends on Tg. Generally, low-Tg resin fine particles tend to have low MFT, but can be adjusted to some extent by controlling the dispersibility of resin fine particles. In the present invention, a film-forming aid may be added to control the MFT of the resin fine particles. The film-forming aid is an organic compound that is also called a plasticizer and lowers the MFT of resin fine particles.

  Similarly, as a method for controlling MFT, resin fine particles modified with an anionic group such as a carboxyl group have an effect that the dispersion ability of resin fine particles is improved by increasing the pH, and the apparent MFT is lowered.

  In the present invention, it is preferable to use a colorless ink which does not substantially contain a colorant, in addition to the colored ink containing a colorant.

  The colorless ink according to the present invention does not substantially contain a colorant, which means that it has substantially no function as an image recording ink liquid. For other purposes, for example, the ink residue. Slight coloring may be applied to confirm the amount, to adjust the color tone of the white background when printing on a white background, to confirm the ejection property, and to improve the weather resistance.

  The colorless ink according to the present invention can contain 0.1 to 50.0% by mass of resin fine particles, more preferably 1 to 20% by mass, and about 1 to 10% by mass from the viewpoint of dispersibility and performance after film formation. Is most preferred. Moreover, 1-50 mass% of water-soluble media (for example, water, a water-soluble organic solvent, etc.) are contained, and each functionality, such as surfactant, a ultraviolet absorber, antioxidant, an anti-bacterial agent, as needed. A compound may be included. As the organic solvent, surfactant, and other additives that can be added to the colorless ink according to the present invention, the same additives as those that can be added to the colored ink containing the colorant described later can be used. .

  Further, when the colorless ink according to the present invention is applied on the ink jet recording medium, the resin film after the film formation with resin fine particles is uniformly formed with a film thickness of 350 nm or more according to the amount of the colored ink applied to the ink jet recording medium. From the viewpoint of obtaining a highly uniform gloss, it is preferable to apply a colorless ink so as to be coated.

  The colorless ink according to the present invention and the later-described colored ink have a surface tension of preferably 40 mN / m or less, preferably 20 to 40 mN / m, in order to stably discharge, and to increase the appearance of high gloss and ozone resistance. More preferably. For the same reason, the ink viscosity is preferably 1.5 to 10 mPa · s, more preferably 3.0 to 8.0 mPa · s.

  In the image forming method of the present invention, examples of the colorant include pigments and dyes. Among them, a water-soluble colorant is preferable. In the present invention, a water-soluble dye is preferably used as the water-soluble colorant contained in the colored ink.

  The colored ink composed of the water-soluble dye according to the present invention is an ink obtained by using a water-soluble dye as a colorant and mixing water or an organic solvent highly miscible with water as an ink solvent.

  As dyes applicable to the present invention, conventionally known azo dyes, xanthene dyes, phthalocyanine dyes, quinone dyes, anthraquinone dyes, etc. were introduced with sulfo groups or carboxy groups to improve water solubility, Acid dyes, direct dyes or basic dyes are typically used.

  Examples of water-soluble dyes that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, diphenylmethane dyes, and the like. The compounds are shown below. However, it is not limited to these exemplified compounds.

<C. I. Acid Yellow>
1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 42, 44, 49, 59, 61, 65, 67, 72, 73, 79, 99, 104, 110, 114, 116, 118, 121, 127, 129, 135, 137, 141, 143, 151, 155, 158, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 220, 230, 232, 235, 241, 242, 246
<C. I. Acid Orange>
3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, 168
<C. I. Acid Red>
1, 6, 8, 9, 13, 18, 27, 35, 37, 52, 54, 57, 73, 82, 88, 97, 106, 111, 114, 118, 119, 127, 131, 138, 143, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415
<C. I. Acid Violet>
17, 19, 21, 42, 43, 47, 48, 49, 54, 66, 78, 90, 97, 102, 109, 126
<C. I. Acid Blue>
1, 7, 9, 15, 23, 25, 40, 62, 72, 74, 80, 83, 90, 92, 103, 104, 112, 113, 114, 120, 127, 128, 129, 138, 140, 142, 156, 158, 171, 182, 185, 193, 199, 201, 203, 204, 205, 207, 209, 220, 221, 224, 225, 229, 230, 239, 249, 258, 260, 264, 278, 279, 280, 284, 290, 296, 298, 300, 317, 324, 333, 335, 338, 342, 350
<C. I. Acid Green>
9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108, 109
<C. I. Acid Brown>
2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357, 413
<C. I. Acid Black>
1, 2, 3, 24, 26, 31, 50, 52, 58, 60, 63, 107, 109, 112, 119, 132, 140, 155, 172, 187, 188, 194, 207, 222
<C. I. Direct yellow>
8, 9, 10, 11, 12, 22, 27, 28, 39, 44, 50, 58, 86, 87, 98, 105, 106, 130, 132, 137, 142, 147, 153
<C. I. Direct orange>
6, 26, 27, 34, 39, 40, 46, 102, 105, 107, 118
<C. I. Direct Red>
2, 4, 9, 23, 24, 31, 54, 62, 69, 79, 80, 81, 83, 84, 89, 95, 212, 224, 225, 226, 227, 239, 242, 243, 254
<C. I. Direct Violet>
9, 35, 51, 66, 94, 95
<C. I. Direct Blue>
1, 15, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 160, 168, 189, 192, 193, 199, 200, 201, 202, 203, 218, 225, 229, 237, 244, 248, 251, 270, 273, 274, 290, 291
<C. I. Direct Green>
26, 28, 59, 80, 85
<C. I. Direct Brown>
44, 106, 115, 195, 209, 210, 222, 223
<C. I. Direct Black>
17, 19, 22, 32, 51, 62, 108, 112, 113, 117, 118, 132, 146, 154, 159, 169
<C. I. Basic Yellow>
1, 2, 11, 13, 15, 19, 21, 28, 29, 32, 36, 40, 41, 45, 51, 63, 67, 70, 73, 91
<C. I. Basic Orange>
2, 21, 22
<C. I. Basic Red>
1, 2, 12, 13, 14, 15, 18, 23, 24, 27, 29, 35, 36, 39, 46, 51, 52, 69, 70, 73, 82, 109
<C. I. Basic Violet>
1, 3, 7, 10, 11, 15, 16, 21, 27, 39
<C. I. Basic Blue>
1, 3, 7, 9, 21, 22, 26, 41, 45, 47, 52, 54, 65, 69, 75, 77, 92, 100, 105, 117, 124, 129, 147, 151
<C. I. Basic Green>
1, 4
<C. I. Basic Brown>
1
<C. I. Reactive Yellow>
2, 3, 7, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 105, 111, 125, 135, 136, 137, 142, 143, 145, 151, 160, 161, 165, 167, 168, 175, 176
<C. I. Reactive Orange>
1, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 107
<C. I. Reactive Red>
2, 3, 5, 8, 11, 21, 22, 23, 24, 28, 29, 31, 33, 35, 43, 45, 49, 55, 56, 58, 65, 66, 78, 83, 84, 106, 111, 112, 113, 114, 116, 120, 123, 124, 128, 130, 136, 141, 147, 158, 159, 171, 174, 180, 183, 184, 187, 190, 193, 194, 195, 198, 218, 220, 222, 223, 228, 235
<C. I. Reactive Violet>
1, 2, 4, 5, 6, 22, 23, 33, 36, 38
<C. I. Reactive Blue>
2, 3, 4, 5, 7, 13, 14, 15, 19, 21, 25, 27, 28, 29, 38, 39, 41, 49, 50, 52, 63, 69, 71, 72, 77, 79, 89, 104, 109, 112, 113, 114, 116, 119, 120, 122, 137, 140, 143, 147, 160, 161, 162, 163, 168, 171, 176, 182, 184, 191, 194, 195, 198, 203, 204, 207, 209, 211, 214, 220, 221, 222, 231, 235, 236
<C. I. Reactive Green>
8, 12, 15, 19, 21
<C. I. Reactive Brown>
2, 7, 9, 10, 11, 17, 18, 19, 21, 23, 31, 37, 43, 46
<C. I. Reactive Black>
5, 8, 13, 14, 31, 34, 39
These dyes listed above are described in “Dyeing Note 21st Edition” (publishing; Color Dyeing Company) and the like.

  On the other hand, as the pigment used in the colored ink according to the present invention, various inorganic or organic pigment inks conventionally known by inkjet can be used. For example, azo pigments such as azo lake pigments, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include polycyclic pigments, dye lakes such as acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.

  Specific organic pigments are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. And CI Pigment Yellow 138.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  The concentration of the dye and the pigment in the colored ink depends on the type of the dye or pigment to be applied, the form in which the ink is used (whether or not the dark and light ink is used), and further on the type of the paper, but is generally about 0.1. 2 to 10% by mass.

  In the colored ink according to the present invention, a water-soluble solvent is preferably used, and as the water-soluble solvent, a mixed solvent such as water and a water-soluble organic solvent is more preferably used. Examples of the water-soluble organic solvent preferably used include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether, ethylene Glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Nomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol Monophenyl ether, propylene glycol monophenyl ether), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetra) , Tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2 -Pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), sulfoxides (for example, dimethyl sulfoxide) and the like.

  In the colored ink, various surfactants can be used for the purpose of increasing the permeability of the ink solvent and other purposes. As such a surfactant, an anionic or nonionic surfactant is preferably used. Of these, acetylene glycol surfactants are particularly preferred.

  The latex-containing ink according to the present invention may contain various known additions depending on the purpose of improving ejection stability, print head and ink cartridge compatibility, storage stability, image storability, and other various performances. Agents, such as viscosity modifiers, surface tension modifiers, specific resistance modifiers, film forming agents, dispersants, surfactants, UV absorbers, antioxidants, anti-fading agents, antifouling agents, rust inhibitors, etc. For example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplet fine particles such as silicone oil, various surfactants such as cation or nonion, JP-A-57-74193, 57- No. 879888 and 62-261476, JP-A-57-74192, 57-87989, 60-72785, 61- No. 46591, JP-A-1-95091 and JP-A-3-13376, etc., and JP-A-59-42993, 59-52689, 62-280069, 61-242871 Examples thereof include fluorescent brighteners and pH adjusters such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, and potassium carbonate described in JP-A-4-219266.

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

<< Preparation of inkjet recording medium >>
[Production of Recording Medium 1]
(Production of non-water-absorbing support)
1 part polyacrylamide, 4 parts ash (talc), 2 parts cationized starch, 0.5 parts polyamide epichlorohydrin resin and 100 parts wood pulp (LBKP / NBSP = 50/50) A slurry liquid containing an appropriate amount of alkyl ketene dimer (sizing agent) was prepared, and a base paper was made using a long paper machine so that the basis weight was 170 g / m ² . After calendering this, a low-density polyethylene resin having a density of 0.92 containing 7% by mass of anatase-type titanium oxide and a small amount of a color tone adjusting agent was melt extruded at a temperature of 320 ° C. to a thickness of 28 μm. One side of the paper was covered and cooled immediately with a mirror cooling roller. Next, the opposite surface was coated with a mixed melt of high density polyethylene of density 0.96 / low density polyethylene of density 0.92 = 70/30 to a thickness of 32 μm by the same melt extrusion method. . The surface on the side where the ink absorbing layer is provided had a 60 ° glossiness of 56% and a centerline average roughness Ra of 0.12 μm.

After corona discharge on the titanium oxide-containing layer side of the support, gelatin was coated with 0.05 g / m ² of gelatin as an undercoat layer.

  On the other hand, on the other side, a dry film thickness of about 0.5 μm of styrene / acrylic emulsion containing silica fine particles (matting agent) with an average particle size of about 1.0 μm and a small amount of cationic polymer (conductive agent) is obtained. Thus, a non-water-absorbing support for applying an ink absorbing layer was produced.

  On the back surface side of this non-water-absorbing support, the glossiness was about 18%, SRa was about 4.5 μm, and Beck smoothness was 160 to 200 seconds.

The water content of the base paper of the non-water-absorbing support thus obtained is 7.0 to 7.2%, the opacity is 96.5%, the whiteness is L ^* = 95.2, a ^* = It was 0.56, b ^* =-4.35.

(Preparation of fine particle dispersion)
<Preparation of titanium oxide dispersion>
20 kg of titanium oxide having an average particle size of about 0.25 μm (Ishihara Sangyo: W-10), 150 g of sodium tripolyphosphate having a pH of 7.5, 500 g of polyvinyl alcohol (Kuraray Co., Ltd .: PVA235), cation After adding the polymer (P-1) to 90 L of an aqueous solution containing 150 g of the polymer and 10 g of the defoaming agent SN381 of Sannobuco Co., Ltd. and dispersing with a high-pressure homogenizer (manufactured by Sanwa Kogyo Co., Ltd.), the total amount is finished to 100 L, and uniform Titanium oxide dispersion was prepared.

<Preparation of silica dispersion 1>
A mixed solution having the following composition was prepared.

Water 71L
Boric acid 0.27Kg
Borax 0.24Kg
Ethanol 2.2L
Cationic polymer (P-1) 25% aqueous solution 17L
Anti-fading agent (AF1 * 1) 10% aqueous solution 0.5L
Optical brightener aqueous solution (W1 * 2) 0.1L
The entire amount was finished to 100 L with pure water.

  50 kg of vapor phase method silica (Aerosil 300, manufactured by Nippon Aerosil Co., Ltd., primary average particle size 7 nm) as inorganic fine particles was added to the above mixed liquid, and the dispersion method described in Example 5 of JP-A-2002-47454 was used. Dispersion gave silica dispersion 1.

* 1: anti-fading agent (AF1) HO-N (C 2 H 4 SO 3 Na) 2
* 2: UVITEX NFW LIQUID manufactured by Ciba Specialty Chemicals
<Preparation of silica dispersion 2>
In the preparation of the silica dispersion 1, the silica dispersion 2 was prepared in the same manner except that the cationic polymer (P-1) was changed to the cationic polymer (P-2).

<Preparation of silica dispersion 3>
A silica dispersion 3 was prepared in the same manner as in the preparation of the silica dispersion 2, except that the inorganic fine particles were changed to vapor phase silica aerosil 380S having a primary average particle diameter of 5 nm manufactured by Nippon Aerosil Co., Ltd.

(Preparation of coating solution)
According to the following content, the coating liquid of the 1st layer, the 2nd layer, the 3rd layer, and the 4th layer was prepared.

<Coating liquid for first layer>
While stirring 610 ml of the silica dispersion 1 prepared above at 40 ° C., the following additives were sequentially mixed to prepare a coating solution for the first layer.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
220ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
Titanium oxide dispersion 30ml
15 ml of polybutadiene dispersion (average particle size: about 0.5 μm, solid content: 40%)
Surfactant (SF1, 5% aqueous solution) 1.5ml
Urea (10% aqueous solution) 10ml
The whole amount was finished to 1000 ml with pure water.

<Second layer coating solution>
While stirring 630 ml of silica dispersion 1 at 40 ° C., the following additives were sequentially mixed to prepare a coating solution for the second layer.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
180ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
15 ml of polybutadiene dispersion (average particle size: about 0.5 μm, solid content: 40%)
Urea (10% aqueous solution) 10ml
The whole amount was finished to 1000 ml with pure water.

<Coating liquid for third layer>
While stirring 650 ml of silica dispersion 2 at 40 ° C., the following additives were sequentially mixed to prepare a third layer coating solution.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
180ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
Urea (10% aqueous solution) 10ml
The whole amount was finished to 1000 ml with pure water.

<Fourth layer coating solution>
While stirring 650 ml of silica dispersion 2 at 40 ° C., the following additives were sequentially mixed to prepare a coating solution for the fourth layer.

5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA235)
180ml
5% aqueous solution of polyvinyl alcohol (Kuraray Industrial Co., Ltd .: PVA245)
80ml
Saponin 50% aqueous solution 4ml
Surfactant (SF1) 5% aqueous solution 6ml
Urea (10% aqueous solution) 10ml
The whole amount was finished to 1000 ml with pure water.

  Each coating solution prepared as described above was subjected to two-stage filtration with a filter capable of collecting 20 μm. Each of the coating solutions exhibited viscosity characteristics of 30 to 80 mPa · s at 40 ° C. and 30000 to 100,000 mPa · s at 15 ° C.

  The pH of the third and fourth layer coating solutions was adjusted to 4.6 at 25 ° C. with acetic acid or sodium acetate.

(Application)
Each coating solution thus obtained was placed on the front side of the produced non-water-absorbing support on the first layer (35 μm), the second layer (45 μm), the third layer (45 μm), and the fourth layer (40 μm). The layers were simultaneously applied so that the order of The inside of parenthesis shows each wet film thickness. The coating was carried out at the same time using a four-layer curtain coater for each coating solution at 40 ° C. with a coating width of about 1.5 m and a coating speed of 100 m / min. Immediately after the coating, it is cooled for 20 seconds in a cooling zone maintained at 8 ° C., then 20 to 30 ° C., relative humidity 20% or less for 30 seconds, 60 ° C./relative humidity 20% or less for 120 seconds, 55 ° C./relative humidity 20% In the following, after drying for 60 seconds, each drying air was blown (the film temperature in the constant rate drying area was 8 to 30 ° C., and the film temperature gradually increased in the decreasing rate drying area), and then 23 ° C. and relative humidity 40 The recording medium 1 was obtained by adjusting the humidity in a humidity control zone of ˜60% and winding up into a roll. The obtained recording medium 1 was kept in a roll shape at 40 ° C. for 5 days and then cut into a predetermined size.

[Preparation of recording medium 2]
According to the method described in Example 1 of JP-A No. 2001-253161 (where the mixing ratio of isocyanate is No. 6) was overcoated on the recording medium 1 prepared above, an isocyanate compound was overcoated, and recording was performed. Medium 2 was produced.

[Preparation of recording medium 3]
In the preparation of the coating solutions for the first to fourth layers used for the production of the recording medium 1, the total amount of polyvinyl alcohol PVA235 and PVA245 was equal to the same amount of high saponification degree polyvinyl alcohol (saponification degree 99.6%, average polymerization degree). A recording medium 3 was produced in the same manner except that the value was changed to ≈ 2400, 5% aqueous solution. This recording medium 3 was kept heated at 55 ° C. for 5 days in the form of a roll.

[Preparation of recording medium 4]
In preparing the coating solutions for the first to fourth layers used in the production of the recording medium 1, the organic polymer WS552 having an epoxy group described in Examples of JP-A-2005-131802 in the third and fourth layer coating solutions. : Polyamide / epichlorohydrin resin was added in an amount of 0.1 g / m ² , and the polyvalent metal compound ZA: zirconyl acetate described in Examples of JP-A No. 2005-131802 was added to the coating solution for the fourth layer. Was prepared in the same manner except that 0.5 g / m ² was added. This recording medium 4 was kept heated at 55 ° C. for 5 days in the form of a roll.

[Preparation of recording media 5 to 8]
(Preparation of impact relaxation layer coating solution 1)
An aqueous solution containing 20% of the silica dispersion 3 as a solid content and 0.3% of a surfactant (Olfin E1010, manufactured by Nissin Chemical) as an active ingredient was prepared.

(Preparation of recording medium)
On each of the ink absorbing layers of the recording media 1 to 4 prepared above, the voids of the ink absorbing layer are filled with pure water by wire bar coating. After applying and drying using a bar coater under the condition that the solid content is 1.2 g / m ² (dry film thickness: equivalent to 2.5 μm), the recording medium 5 is subjected to heat treatment at 55 ° C. for 24 hours. ~ 8 were prepared respectively.

[Preparation of recording media 9 to 13]
(Preparation of impact relaxation layer coating solution 2)
Cationic colloidal silica (Snowtex AK-M, average particle size 22 nm, manufactured by Nissan Chemical Industries, Ltd.) as a solid content concentration of 10%, surfactant (Olfin E1010, manufactured by Nissin Chemical) as an active ingredient is 0.3%. % Aqueous solution was prepared, and this was designated as impact relaxation layer coating solution 2.

(Recording medium production)
The prepared impact relaxation layer coating liquid 2 is applied to each of the fourth ink absorbing layers of the recording media 1 to 4 prepared above, as shown in FIGS. 1 to 7 of JP-A-2004-106378. Using a spray device, the solid content was applied to 0.5 g / m ² and dried, followed by heat treatment at 55 ° C. for 24 hours to prepare recording media 9-12. A recording medium 13 was prepared in the same manner except that the impact relaxation layer coating liquid 2 was applied on the ink absorbing layer of the recording medium 1 so that the solid content was 0.1 g / m ₂ .

<< Preparation of ink set (ink composition) >>
[Preparation of ink set 1]
(Preparation of colored ink set 1)
Colored ink set 1 was prepared as follows. The colored ink set 1 includes dark inks of yellow ink (Y), magenta ink (M), cyan ink (C) and black ink (K), and light magenta ink (Lm) and light cyan ink (Lc). Each of the light-colored inks was composed of six colors, and each was mixed as follows, and then triethanolamine was added dropwise to adjust the pH to a range of 9.0 ± 0.3. Next, after filtration through a 3 μm membrane filter, it was filled into an empty ink cartridge.

<Dark color ink: Preparation of yellow ink (Y)>
Dye: Direct Yellow 86 3.0% by mass
Diethylene glycol 13% by mass
Glycerin 10% by mass
Triethylene glycol monobutyl ether 5.0% by mass
Resin fine particles (SX1105A: manufactured by Nippon Zeon, styrene-butadiene copolymer resin (anion-modified latex), Tg: 0 ° C., average particle size: 109 nm)
1.5% by mass in terms of solid content
Surfactant (Surfinol 465: manufactured by Air Products) 1.0% by mass
Pure water was added to finish 100% by mass.

<Dark color ink: Preparation of magenta ink (M), cyan ink (C) and black ink (K)>
Magenta ink (M) and cyan ink (C) were prepared in the same manner as in the preparation of the yellow ink (Y) except that the dye was changed to direct red 227, direct blue 199, and food black 2 instead of direct yellow 86, respectively. ) And black ink (K).

<Light ink: Preparation of light magenta ink (Lm)>
Dye: Direct Red 227 0.8% by mass
Diethylene glycol 10% by mass
Glycerin 10% by mass
10% by mass of triethylene glycol monobutyl ether
Resin fine particles (SX1105A: manufactured by Nippon Zeon, styrene-butadiene copolymer resin (anion-modified latex), Tg: 0 ° C., average particle size: 109 nm)
1.0% by mass in terms of solid content
Surfactant (Surfinol 465: manufactured by Air Products) 0.8% by mass
Pure water was added to finish 100% by mass.

<Light ink: Preparation of light cyan ink (Lc)>
A light cyan ink (Lc) was prepared in the same manner as in the preparation of the light cyan ink (Lc), except that the direct blue 199 was used instead of the direct red 227.

(Preparation of colorless ink 1)
Diethylene glycol 10% by mass
Glycerin 10% by mass
10% by mass of triethylene glycol monobutyl ether
Resin fine particles (SX1105A: manufactured by Nippon Zeon, styrene-butadiene copolymer resin (anion-modified latex), Tg: 0 ° C., average particle size: 109 nm)
2.0 mass% in terms of solid content
Surfactant (Surfinol 465: manufactured by Air Products) 0.5% by mass
After pure water was added to finish 100% by mass, triethanolamine was added dropwise to adjust the pH to a range of 9.0 ± 0.3. Next, after filtration through a 3 μm membrane filter, it was filled into an empty ink cartridge.

  As described above, ink set 1 composed of colored ink set 1 and colorless ink 1 was prepared.

<Inkjet image recording>
Using the ink jet recording apparatus shown in FIG. 1, using the ink set 1 composed of the colored ink set 1 and the colorless ink 1, the recording materials 1 to 13 were prepared by discharging onto the recording media prepared above.

  As shown in FIG. 1, the amount of ink droplets per discharge operation can be adjusted, and yellow ink (Y), magenta ink (M), cyan ink (C), and black ink (color ink) as dark ink. K), and a piezo-type ink jet recording apparatus equipped with recording heads of six colors of light magenta ink (Lm) and light cyan ink (Lc) and colorless ink as light color inks. Each colored ink was image-formed with a droplet volume of 4 pl and a recording resolution of 1440 × 1440 dpi (dpi: representing the number of dots per 2.54 cm).

The colorless ink can variably control the amount of droplets and the amount of adhesion to the recording paper. The recording resolution is 14400 × 1440 dpi, and the total amount of the colored ink and the total discharge amount of the colored ink is 17 ml / m at the same time as the image formation with the colored ink. ^A surface film was formed by controlling the discharge amount of colorless ink so as to be ² .

  The ink jet recording apparatus shown in FIG. 1 used for the printing will be further described.

  In FIG. 1, the recording head 22 for colored ink and the recording head 22 for colorless ink were used, and an image was printed with colored ink and a protective film layer was formed with colorless ink using a carriage arranged in series.

  The recording head 22 may normally be any of a piezo method, a thermal method, and a continuous method, but in this embodiment, the piezo method was used from the viewpoint of the ejection stability of ink containing resin fine particles.

  Each recording head 22 is supplied with ink from a colored ink cartridge and a colorless ink cartridge (not shown) through a tube for piping. Seven recording heads 22 are arranged along the scanning direction, and are used for six colored inks and colorless inks, respectively.

<Evaluation of formed image>
[Measurement of scratch load]
The unprinted portion of the following recording medium was measured for the scratch load on the surface of the recording medium by a dry scratch test. Using a Haydon-18 scratch strength meter Haydon-18, under a 25 ° C. and 55% RH environment, the load speed was changed from 0 to 100 g using a 0.2 mmφ sapphire needle at a moving speed of 10 mm / second, and the damage was clearly observed. The load recognized as a flaw was measured.

[Evaluation of resistance to ozone fading of scratched part]
From the inkjet recording apparatus shown in FIG. 1, yellow ink (Y), magenta ink (M), cyan ink (C), and black ink (K) as dark inks, and light magenta ink (Lm) and light cyan as light inks. Each color of yellow ink, each magenta ink, each cyan ink, and black ink using an algorithm that uses 6 inks of ink (Lc) and 7 kinds of inks of colorless ink and the total ink application amount is 17 ml / m ² Ink and colorless ink were ejected at the same time to produce a gray solid image with an optical density of 1.0.

  Next, on the gray solid image, a scratch strength meter Haydon-18 manufactured by Haydon Co., Ltd. was used to change the load by 0 to 100 g with a 0.2 mmΦ sapphire needle, and the scratches were given (moving speed 10 mm / mm in a 25 ° C. and 55% RH environment). Seconds). Next, the gray solid image with scratches was continuously exposed using an ozone tester (Ozone Weather Meter OMS-H manufactured by Suga Test Machine Co., Ltd.) at a concentration of 10 ppm per hour until the total exposure reached 100 ppm. After that, the load value which started to cause fading due to ozone gas intrusion from the wound was read. The numerical value of 0-100 shown in Table 1 represents the load (g) at that time, and it shows that the ozone tolerance by a damage | wound is so high that a numerical value is large.

[Evaluation of ink absorbency]
From the inkjet recording apparatus shown in FIG. 1, yellow ink (Y), magenta ink (M), cyan ink (C), and black ink (K) as dark inks, and light magenta ink (Lm) and light cyan as light inks. A blue gradation image and a green gradation image are combined with each ink using an algorithm that discharges six types of ink (Lc) and seven types of colorless ink under the condition that the total ink application amount is 17 ml / m ^2. A red gradation image and a black gradation image were formed.

  Each gradation image formed as described above was visually observed, and ink absorptivity was evaluated according to the following criteria.

◎: There is no density mottle due to ink overflow, and the image is uniform. ○: A slight density mottle is observed in some images in a specific density range, but the image is almost uniform. Δ: Although weak density mottle is confirmed in images of several colors, the quality is acceptable for practical use. ×: Strong density mottle and gloss unevenness are confirmed in images of all colors, and the quality becomes a problem in practical use. In addition, when generation | occurrence | production of the reflected light (bronzing) accompanying a hue change like metallic luster was recognized in the glossy part, it was the quality which becomes a problem in practical use, and it determined with x.

  The results obtained as described above are shown in Table 1.

  As is clear from the results shown in Table 1, the recorded matter of the present invention formed using an inkjet ink composed of a colored ink containing latex and a colorless ink on a void-type recording medium having an impact relaxation layer is as follows. It can be seen that, compared to the comparative example, it has excellent ozone fading resistance when scratches are imparted and has good ink absorbability.

It is a perspective view which shows an example of the inkjet printer used with the inkjet recording method of this invention.

Explanation of symbols

22 Recording head 23 Carriage

Claims (5)

In an image forming method in which an inkjet ink containing latex is jetted onto a void-type inkjet recording medium to perform inkjet printing, the void-type inkjet recording medium has at least two constituent layers, and at least one of the constituent layers is An image forming method comprising an impact relaxation layer that absorbs external pressure. The image forming method according to claim 1, further comprising a high-strength layer subjected to a curing process at a lower portion adjacent to the impact relaxation layer. The impact-reducing layer is a layer containing silica fine particles or alumina fine particles and having a dry film thickness that is substantially free of a binder and is 0.1 μm or more and 3.0 μm or less. Image forming method. The impact-reducing layer is a layer containing colloidal silica or colloidal alumina and having a dry film thickness substantially not including a binder of 0.1 μm or more and 3.0 μm or less. Image forming method. 5. At least one of the latex-containing inkjet inks is a colorless ink substantially free of a colorant, and the other inkjet inks are colored inks containing a colorant. The image forming method according to any one of the above.

Images