JP5152126B2 - Inkjet recording medium - Google Patents

Description

  The present invention relates to an ink jet recording material. More specifically, the present invention relates to an ink jet recording body in which undulation (hereinafter also referred to as cockling) due to support expansion and contraction during printing or after printing is suppressed.

The ink jet recording method that ejects water-based ink from a fine nozzle toward the ink jet recording body to form an image on the surface of the ink jet recording body has low noise during recording, easy formation of a full color image, high speed It is widely used in terminal printers, facsimiles, plotters, form printing, and the like due to the fact that recording is possible and the recording cost is lower than other printing apparatuses.
In addition, improvement of the ink itself used is also progressing, and water resistance and light resistance are excellent together with a water-based dye ink (hereinafter also referred to as a dye ink) using a highly hydrophilic colorant which has been a mainstream in the past. Ink in which a hydrophobic coloring pigment is dispersed (hereinafter also referred to as pigment ink) is often used.

In recent years, due to the rapid spread of printers and high definition and high speed, there has been a strong demand for improving the ink absorption speed and realizing image uniformity comparable to silver salt photography and plate-making multicolor printing. Further, further improvement in image recording density and smoothness is desired for the quality of recorded images.
In order to realize an image equivalent to a silver salt photograph, the amount of ink discharged from the printer is also increasing. In an ink jet recording medium using a paper base, water, which is an ink solvent, permeates the paper base and cockling. This causes problems such as rubbing with the recording head during printing to disturb the image, and cockling remains after image recording, which impairs the appearance of the printed matter.

In order to solve such problems, resin-coated paper in which a thermoplastic resin such as polyethylene is laminated on both sides has been commonly used in inkjet recording materials, but the resin-coated paper is recovered as used paper and recycled as used paper pulp. Attempting to do so may leave the coated resin and cause trouble.
In order to solve the above problems, various studies have been made on an ink jet recording medium using a paper substrate. For example, (a) a water-permeable intermediate layer is formed by coating a thermoplastic resin dispersion on the surface of a paper substrate of an ink jet recording material, and then a pigment and a binder are formed on the surface of the water-permeable intermediate layer. A method of forming an ink-receiving layer by coating a coating solution containing (for example, refer to Patent Document 1), (i) providing an undercoat layer and an ink fixing layer on a paper substrate, and as a pigment for the undercoat layer, A method using a flat pigment having an average particle diameter of 4 to 50 μm and an aspect ratio of 5 to 70 (see, for example, Patent Document 2), (U) Low density that reduces the interfiber binding of pulp and increases the voids of paper A method using a base material containing a chemical (for example, see Patent Document 3) has been proposed.
However, in the methods (a) and (ii), since a layer containing only a binder or a pigment having low absorbability is provided between the paper substrate and the ink receiving layer, the adhesion to the ink receiving layer is improved. Unfortunately, there was a problem that paper dust was generated during cutting. In the method (ii), cockling during printing or after printing is not sufficiently prevented in an image with a large amount of ink.

JP 2002-103787 A JP 2006-015584 A JP 2002-103791 A

  The present invention provides an ink jet recording body that suppresses cockling during printing or after printing, has no bleeding, has good ink absorbability, has high recording layer adhesion, and generates less paper dust during cutting. It is in.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research on the undercoat layer based on the invention described in Patent Document 2, and as a result, have adopted an ink solvent absorption delay layer having a specific configuration. As a result, the inventors have found that this can be achieved, and have reached the present invention.

(1) An inkjet recording medium having an ink solvent absorption delay layer and a recording layer on at least one surface of the support, and the ink solvent absorption delay layer provided between the support and the recording layer has an average particle size of 1. An ink jet recording material comprising: a flat pigment having a size of 5 μm or less and a water-dispersible latex binder in a ratio of 100 to 2000 parts by mass of a water-dispersible latex binder with respect to 100 parts by mass of the flat pigment.
The ink solvent absorption delay layer prevents cockling by preventing the solvent in the ink during recording from being absorbed by the support, and after a while after recording, the solvent gradually permeates the support. It is a layer for the purpose of separating the colorant (dye or colored pigment) and the solvent therein, and a flat pigment having an average particle diameter smaller than that of the flat pigment described in Patent Document 2 is adopted, and the amount of latex binder is By adopting the increased configuration, both the improvement of the adhesion of the recording layer and the effect of suppressing cockling are achieved.
(2) The ink jet recording material according to (1), wherein the ink solvent absorption delay layer contains a crosslinking agent.
(3) The inkjet recording material according to (1) or (2), wherein the coating amount of the ink solvent absorption delay layer is 1.5 to 6.0 g / m ² .
(4) The ink jet recording material according to any one of (1) to (3), wherein the flat pigment is kaolin.

  The ink jet recording material obtained in the present invention is an ink jet which suppresses cockling during printing or after printing, does not bleed, has good ink absorbability, has high recording layer adhesion, and generates less paper dust during cutting. It relates to a recording medium.

  The present invention is an ink jet recording body having a layer structure in which at least an ink solvent absorption delay layer and a recording layer are sequentially provided on a support. Each configuration will be described below.

<Support>
Although the support is not particularly limited, the present invention provides an ink jet recording body in which cockling is suppressed by forming an ink solvent absorption delay layer and a recording layer, and thus cockling is likely to occur. Suitable for application to fibrous supports. Examples of the fibrous support include a paper base material, woven fabric, and non-woven fabric, but a paper base material is often used for handling. As the paper substrate, fine paper, art paper, coated paper, cast coated paper, kraft paper, baryta paper, impregnated paper, vapor-deposited paper, and the like are appropriately used.

The paper base is composed mainly of wood pulp. The wood pulp is not particularly limited in production method and type, for example, chemical pulp such as KP, mechanical pulp such as SGP, RGP, BCTMP, and CTMP, waste paper pulp such as deinked pulp, kenaf, bamboo, straw, Various chemical pulps such as non-wood pulp such as hemp and the like, mechanical pulps, recycled pulps and the like can be used, and the beating degree can be adjusted by a beating machine in order to adjust paper strength, papermaking suitability and the like.
The beating degree (freeness) of the pulp is not particularly limited, but is generally about 250 to 550 ml (CSF: JIS P8121). In order to improve smoothness, it is desirable to advance the beating degree. However, when recorded on paper, paper blur and recording image bleeding caused by moisture in the ink often gives better results if the beating is not advanced. . Accordingly, the freeness is preferably about 300 to 500 ml.

  Moreover, a filler may be blended in the support as necessary. As the filler, various commonly used pigments can be used, for example, kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, alumina silicate. Mineral pigments such as silica, white carbon, bentonite, zeolite, sericite and smectite. In particular, calcium carbonate is preferable because it becomes a support having high whiteness and the high-quality feeling of the ink jet recording material is enhanced. The content (ash content) of the filler in the support is preferably about 1 to 20% by mass, and if it is too much, the paper strength may be reduced. When the amount is too small, the air permeability is deteriorated, so the preferable filler content is 3 to 20% by mass. Within this range, the smoothness, air permeability, and paper strength are balanced, and as a result, an ink jet recording material with excellent smoothness can be easily obtained.

A sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improving agent, a dye, a fluorescent brightening agent, and the like can be added to the support as auxiliary agents. Furthermore, in the size press process of the paper machine, starch, polyvinyl alcohol, cationic resin and the like can be applied and impregnated to adjust the surface strength, sizing degree, and the like. The Steecht sizing degree (as 100 g / m ² paper) is preferably 1 to 200 seconds. If the sizing degree is high, the ink absorbability may be lowered, and the occurrence of curling and cockling after printing may be significant. A more preferred range of sizing is 5 to 120 seconds. Although the basic weight of a base material is not specifically limited, It is about 20-400 g / m < ² >. The range of 50 to 250 g / m ² is particularly preferable for printing applications. A range of 60 to 200 g / m ² is most preferred.

<Ink solvent absorption delay layer>
The ink solvent absorption delay layer is a layer containing a flat pigment and a water-dispersible latex binder.

"Plate pigment"
The ink solvent that has permeated from the recording layer is blocked from reaching the support by the flat pigment, so that the speed of reaching the support is slower than when the flat pigment is not used. Once the ink solvent is blocked, the ink solvent passes between the flat pigments and reaches the support. When the penetration rate into the support becomes slow, the elongation due to water absorption of the support is suppressed, so that cockling can be prevented. Examples of the flat pigment include clay minerals such as kaolin and phyllosilicate minerals such as talc and mica group. Of these, the use of kaolin is preferred.

  The average particle size of the tabular pigment needs to satisfy 1.5 μm or less. Incidentally, in the case of exceeding 1.5 μm, although the effect of suppressing the penetration of the ink solvent is exhibited, the binder in the recording layer coating liquid when forming the recording layer does not sufficiently soak into the ink solvent absorption delay layer. The adhesion of the recording layer will be impaired. A preferable average particle diameter is 1.0 μm or less, more preferably 0.8 μm or less. The lower limit is not particularly limited, but if it is too fine, it will not show a flat shape, and even if it shows a flat shape, the effect of suppressing the penetration of the ink solvent tends to decrease, so the preferred average particle size is 0.2 μm or more, more preferably 0.3 μm or more. The average particle diameter here employs a value measured by an X-ray transmission type sedimentation method. Probably because it is the principle of measurement in a state where the pigment settles in the liquid, the ink solvent absorption delay layer is measured in a state close to the lamination condition of the flat pigment at the time of coating. It is considered that the average particle diameter of the tabular pigment is being measured. As the measuring device, a disk centrifugal sedimentation type particle size distribution measuring device BI-XDC manufactured by Nikkiso Co., Ltd., a Sedigraph manufactured by Micromeritics, etc. are commercially available. In the present invention, a Cedigraph 5100 manufactured by Micromeritics was used. Value.

  There is an aspect ratio as an indication of a flat shape. The aspect ratio is obtained by dividing the diameter of the tabular pigment by the thickness of the tabular pigment, and the larger the value, the flatter. The aspect ratio may be a catalog value of a commercially available flat pigment to be used, but when the aspect ratio is not described, or when the flat pigment is crushed, the diameter obtained by observing with an electron microscope and A value obtained from the thickness may be adopted. The aspect ratio of the tabular pigment used in the present invention is preferably 5 or more. If it is less than 5, the effect of suppressing the penetration of the ink solvent may not be sufficiently obtained. The upper limit of the aspect ratio is not particularly limited, but those having an average particle diameter of 1.5 μm or less are marketed up to about 100 and can be used. In addition, a preferable aspect ratio is 5-100, More preferably, it is 30-80.

  In the ink solvent absorption delay layer, various publicly known pigments in the field of coated paper can be used as long as the effects of the present invention are not impaired. Dry silica, wet silica, heavy calcium carbonate, light calcium carbonate , Calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, calcium silicate, magnesium silicate, aluminum hydroxide, alumina, magnesium carbonate, magnesium hydroxide and other inorganic pigments, acrylic or Methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyester resin, styrene-acrylic resin, styrene-butadiene resin, styrene-isoprene resin, polycarbonate resin, silicone resin, urea resin, melamine resin , Epoxy resin, phenol Resins, organic pigments made of resins such as diallyl phthalate resin, silica composite calcium carbonate, and various composite materials of the silica-alumina composite particles and the like. Among these, calcium carbonate and wet method silica, which have a wide variety of particle diameters and are superior in cost, are preferable.

"Water-dispersible latex binder"
The water-dispersible latex binder used in the ink solvent absorption delay layer is an emulsion in which a water-insoluble thermoplastic polymer compound is dispersed in water, and is distinguished from water-soluble synthetic resins in that it does not dissolve in hot water after drying. Is done. Examples thereof include styrene butadiene latex (SBR), acrylic styrene latex, methacrylate butadiene latex, acrylonitrile butadiene latex and the like, and styrene butadiene latex is preferable from the viewpoint of coating strength. Here, the polymerizable monomer is mainly composed of styrene and 1,3-butadiene, but other monomers copolymerizable with styrene and 1,3-butadiene are used as long as the object of the present invention is not impaired. be able to. Other monomers copolymerizable with styrene and 1,3-butadiene include aromatic vinyl monomers such as α-methylstyrene, vinyltoluene, pt-butyltoluene, and chlorostyrene; (meth) acrylic Methyl methacrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , (Meth) acrylic acid ester monomers such as (meth) acrylic acid n-octyl, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid hydroxypropyl; cyano group-containing ethylenic acid such as (meth) acrylonitrile Unsaturated monomer; Glycid of ethylenically unsaturated acids such as glycidyl acrylate and glycidyl methacrylate Glycidyl ethers of unsaturated alcohols such as allyl glycidyl ether; (meth) acrylamides such as (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide These polymerizable monomers can be used singly or in combination of two or more.

"Mixing ratio of pigment and water-dispersible latex binder"
The blending ratio of the pigment and the water-dispersible latex binder in the ink solvent absorption delay layer needs to be 100 to 2000 parts by mass of the water-dispersible latex binder with respect to 100 parts by mass of the total pigment, 150-1800 mass parts is preferable from the balance of film strength, and 1800-1500 mass parts is more preferable. When the water-dispersible latex binder is less than 100 parts by mass, the effect of suppressing the penetration of the ink solvent cannot be sufficiently obtained. When the amount exceeds 2000 parts by mass, the binder in the recording layer coating liquid is the ink solvent absorption delay layer. Therefore, the adhesiveness of the recording layer is impaired, and paper dust is easily generated during cutting.

"Crosslinking agent"
The ink solvent absorption delay layer is formed by applying a coating liquid containing the above latex and a flat pigment, and a crosslinking agent can be blended in the coating liquid as necessary. Is preferably blended. The crosslinking agent exhibits a crosslinking property with a part of the binder contained in the recording layer coated thereon. When a cross-linking agent is blended, it can be cross-linked with the binder of the recording layer coating liquid coated thereon, and the strength of the resulting recording layer and the strength between the ink solvent absorption delay layer and the recording layer can be increased.

  Examples of the crosslinking agent include aldehyde compounds such as boron compounds, formaldehyde, glyoxal, succinaldehyde, glutaraldehyde, dialdehyde starch, and dialdehyde derivatives of plant gum; diacetyl, 1,2-cyclopentanedione, 3-hexene Ketone compounds such as -2,5-dione; active halogen compounds such as bis (2-chloroethyl) urea, bis (2-chloroethyl) sulfone, 2,4-dichloro-6-hydroxy-s-triazine sodium salt; Divinyl sulfone, 1,3-bis (vinylsulfonyl) -2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide), divinyl ketone, 1,3-bis (acryloyl) urea, 1,3,5 -Activities such as triacryloyl-hexahydro-s-triazine N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin; melamine compounds such as trimethylolmelamine, alkylated methylolmelamine, melamine, benzoguanamine, and melamine resin; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, Epoxy compounds such as polyethylene glycol diglycidyl ether, diglycerin polyglycidyl ether, spiroglycol diglycidyl ether, polyglycidyl ether of phenol resin; isocyanate compounds such as 1,6-hexamethylene diisocyanate and xylylene diisocyanate, aziridine type Compounds, carbodiimide compounds, ethyleneimino such as 1,6-hexamethylene-N, N′-bisethyleneurea Compounds, halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid, dioxane compounds such as 2,3-dihydroxydioxane, titanium lactate, aluminum sulfate, polyaluminum chloride, chromium alum, potash alum, zirconyl acetate , Metal-containing compounds such as chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide; low molecules or polymers containing two or more oxazoline groups, polyhydric acid anhydrides, acid chlorides, bis A sulfonate compound, an active ester compound, etc. are mentioned, It may be used independently and can also be used in combination of 2 or more type.

In many cases, polyvinyl alcohol is used as the binder of the recording layer. In this case, it is preferable to use a boron compound as the crosslinking agent.
Examples of the boron compound include borax, boric acid, borate (orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diboric acid. Salt (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na _{2 B 4 O 7 · 10H 2 O} ), five borate _{(e.g., KB 5 O 8 · 4H 2} O, Ca 2 B 6 O 11 · 7H 2 O, include a _CsB 5 _{O 5),} and among them, promptly Borax is preferred in terms of reaction.

  The coating liquid for the ink solvent absorption delay layer further includes a thickener, an antifoaming agent, a wetting agent, a surfactant, a colorant, an antistatic agent, a light fastness auxiliary agent used in general coated paper production, Various auxiliary agents such as ultraviolet absorbers, antioxidants, and preservatives are added as appropriate.

  The ink solvent absorption delay layer can be formed by various known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, and a die coater. .

The dry coating amount of the ink solvent absorption delay layer is not particularly limited, but is preferably 1.5 to 6.0 g / m ² . By setting the dry coating amount to 1.5 g / m ² or more, the support can be sufficiently coated, the speed at which the ink solvent reaches the support can be delayed, and the cockling suppressing effect can be ensured. When the dry coating amount is 6.0 g / m ² or less, the barrier property of the ink solvent absorption delay layer is prevented from increasing, and the ink solvent after recording permeates the support. The absorptivity as an ink jet recording material can be maintained.

<Recording layer>
The recording layer is a layer mainly composed of a pigment and a binder, and is a target layer for fixing a colorant (dye or colored pigment) of ink for inkjet recording.

(Pigment of recording layer)
As the pigment of the recording layer, materials used in known ink jet recording materials can be used. Amorphous silica, light calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin Inorganic pigments such as white, aluminum silicate, calcium silicate, magnesium silicate, aluminum hydroxide, alumina, magnesium carbonate, magnesium hydroxide; acrylic or methacrylic resins, vinyl chloride resins, vinyl acetate resins, polyester resins, styrene Organic pigments made of resins such as acrylic resins, styrene-butadiene resins, styrene-isoprene resins, polycarbonate resins, silicone resins, urea resins, melamine resins, epoxy resins, phenol resins, diallyl phthalate resins Mentioned These pigments may be irregular in spherical. You may use these pigments 1 type or in mixture of 2 or more types. Various composite materials such as silica composite calcium carbonate and silica / alumina composite particles can also be used.

Among these pigments, it is preferable to contain a pigment having an oil absorption of 200 to 400 ml / 100 g. When the amount of oil absorption is less than 200 ml / 100 g, the ink absorbability is lowered, and when it exceeds 400 ml / 100 g, the coating film strength is lowered and the printing density is also lowered. Amorphous silica is preferred as the pigment because it has a high ink absorption speed and little bleeding.
The amorphous silica may be produced by any of the electric arc method, dry method, and wet method (precipitation method, gel method), but from the viewpoint of dye ink and pigment ink absorbability and coating layer strength. Wet silica is particularly preferred.

The average particle diameter of the secondary particles of amorphous silica is preferably 2 to 12 μm, and more preferably 4 to 10 μm. When the average particle size is less than 2 μm, when used for ink jet recording paper for dye ink, the dye ink absorbability is reduced and the light transmittance is further increased, so the light resistance of the recording with the dye ink is lowered. In addition, the coating strength also decreases. In addition, when used for inkjet recording paper for pigment ink, there is an adverse effect that the fixability of the pigment ink is lowered. On the other hand, when the secondary particle diameter of the amorphous silica exceeds 12 μm, both the inkjet recording paper for dye ink and the recording paper for pigment ink have noticeable deterioration in image sharpness and surface roughness, and printing unevenness is likely to occur. This causes problems.
In the present invention, the average particle diameter of the amorphous silica is based on the Coulter counter method and represents the volume average particle diameter measured using a sample obtained by ultrasonically dispersing silica in distilled water for 30 seconds. is there.

(Binder for recording layer)
As the binder in the recording layer, known binders for ink jet recording materials can be used. Known binders include proteins such as casein, soy protein, synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohol and derivatives thereof, cellulose derivatives such as polyvinylpyrrolidone, carboxymethylcellulose and methylcellulose, and styrene-butadiene resins. , Conjugated diene resins such as methyl methacrylate-butadiene copolymer, acrylic resins that are polymers or copolymers such as acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, ethylene-vinyl acetate copolymer, etc. Vinyl resins, acrylic ester copolymers having polyvinyl alcohol as a protective colloid, polyurethane resins, polyamide resins, etc. These may be used alone or in combination with two or more binders. May be.

  The compounding ratio of the amorphous silica and the binder of the present invention is contained in the range of 5 to 50 parts by mass of the binder with respect to 100 parts by mass of the amorphous silica. When the amount of the binder is less than 5 parts by mass, the layer strength of the ink receiving layer becomes weak, and when it exceeds 50 parts by mass, the ink absorbability is lowered and bleeding occurs.

(Other)
An ink fixing agent can be used for the recording layer. As the ink fixing agent to be used, a known cationic compound can be used as an ink fixing agent for an ink jet recording material. Examples of known cationic compounds include 1) polyalkyleneamines such as polyethyleneamine and polypropylene, or derivatives thereof, 2) acrylic resins having tertiary amine groups and quaternary ammonium groups, and 4) dicyandiamide-formalin polycondensates. dicyan cationic resins, 5) dicyandiamide - polyamine cationic resin represented by diethylenetriamine polycondensate, 6) dimethylamine - epichlorohydrin addition polymers, 7) diallylamine salt -SO ₂ copolymer, 8) dimethyldiallylammonium Chloride polymer, 9) polymer of allylamine salt, 10) homopolymer or copolymer of vinylbenzyltriallylammonium salt, 11) dialkylaminoethyl (meth) acrylate quaternary salt copolymer, 12) acrylamide-diallyl Examples thereof include amine salt copolymers, 13) aluminum salts such as polyaluminum chloride and polyaluminum acetate, and commercially available products such as cationic surfactants, which may be used alone or in combination.

  1-60 mass parts is preferable with respect to 100 weight part of pigments, and, as for the mixture ratio of a cationic compound, More preferably, it is 5-50 mass parts. If the cationic compound is less than 1 part by mass, the color developability of the image and the storability of the printed part are liable to decrease, and if it exceeds 60 parts by mass, the ink absorptivity decreases, uneven printing, Decrease in sharpness easily occurs.

  For the recording layer, thickeners, antifoaming agents, wetting agents, surfactants, colorants, antistatic agents, light fastness aids, UV absorbers, antioxidants used in the production of general coated papers Various auxiliary agents such as preservatives and crosslinking agents are appropriately added.

The coating amount of the recording layer is preferably set to 5 to 40 g / ^{m 2,} and more preferably, 8~35g / ^{m 2.} If the coating amount is less than 5 g / m ² , ink absorbability, image sharpness, and print storage stability are liable to deteriorate, and if the coating amount is more than 40 g / m ² , the coating strength and image sharpness are low. It tends to decline. A plurality of recording layers may be laminated, and in that case, the recording layer composition may be different between the layers.

  This recording layer can be formed by various known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, and a die coater.

The drying condition of the recording layer is adjusted by the concentration of the recording layer coating solution, etc., but the behavior of the absorption rate varies depending on the drying condition. The treatment is preferably performed under as strong a drying condition as possible, but excessive drying tends to reduce the color developability.
In addition, after coating, finishing treatment may be performed using a calendar such as a machine calendar, a super calendar, or a soft calendar. However, since such treatment also crushes voids on the surface of the ink receiving layer, it does not impair printability. It is necessary to prepare in a range.

(Layer structure)
In the layer structure of the ink jet recording material of the present invention, the same ink solvent absorption delay layer and recording layer may be provided on both surfaces of the substrate. In this case, clear printing can be performed on both sides of the ink jet recording medium.
The recording layer may be composed of a plurality of layers. For example, by adopting a configuration in which an ink solvent absorption layer and an ink fixing layer are provided from the ink solvent absorption delay layer side, the colorant (dye or colored pigment) and the solvent in the ink can be quickly separated. Further, a configuration in which an ink fixing layer and a glossy expression layer are provided may be employed, or a configuration in which an overcoat layer for improving the storage stability is provided on the ink fixing layer.

In the formation of the gloss layer, cast processing such as a cast method using a heated mirror drum, which will be described later, or a film transfer method is performed.
In such a casting process, a release agent can be used for the purpose of imparting releasability from a cast drum or film.

As the mold release agent, a mold release agent used in the production of ordinary printing coated paper or printing cast coated paper can be used. Specific examples of such release agents include polyolefin waxes such as polyethylene wax and polypropylene wax, higher fatty acid alkali salts such as calcium stearate, zinc stearate, potassium oleate, and ammonium oleate, silicone oil, and silicone. Examples thereof include silicone compounds such as wax, fluorine compounds such as polytetrafluoroethylene, lecithin, and higher fatty acid amides. From the viewpoint of operational stability, it is desirable to use nonionic polyethylene wax.
This release agent is used by being added to the coating solution.

<Calendar processing>
In addition, after forming the recording layer, a finishing process may be performed using a calendar such as a machine calendar, a super calendar, or a soft calendar. However, such a process also destroys the voids on the surface of the recording layer, which impairs printability. It is necessary to carry out in the range which is not.
In addition, the smoothness of at least one of the ink solvent absorption delay layer and the recording layer by applying pressure with a calender can improve the unevenness of the surface of the ink jet recording body and improve the glossiness and smoothness of appearance. It is. The calendar pressure is preferably 20 to 250 kg / cm. If the calender pressure is lower than 20 kg / cm, the smoothing effect cannot be obtained. If the calender pressure is higher than 250 kg / cm, the recording layer and the like are too crushed and the ink absorbability is inhibited. More preferably, it is 30-180 kg / cm.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example are solid content except water, and show a mass part and mass%, respectively.

The ink jet recording materials obtained in each Example and Comparative Example were evaluated for the cockling resistance, paper dust, ink absorbency, blur, and print density by the following methods.
In the evaluation, printing on the ink jet recording medium was performed with a commercially available pigment ink jet printer (trademark: ImagePROGRAF W8400, print mode: thick-coated paper / clean) manufactured by CANON.

[Cockling resistance]
Black solid was printed with the above ImagePROGRAF W8400, and the printed portion was evaluated visually and with texture.
A: There is no undulation of the printing part, and it is flat after printing.
○: There is almost no undulation of the printing part, and it is almost the same as printing paper.
Δ: Waviness is observed in the printed part, but there is no practical problem.
X: Swelling is conspicuous and is a practically problematic level.

[Paper dust]
The blank paper portion of the ink jet recording body was cut with an NT cutter for 10 m and collected with an adhesive tape, and then the amount of the obtained paper powder was visually observed and evaluated by the following method.
A: Almost no paper dust is generated, and an excellent level.
○: Paper dust is generated, but there is no practical problem.
Δ: Paper dust is generated, but it can withstand use.
X: The amount of generated paper dust is very large, which is a serious problem in practical use.

[Ink absorbency]
A green and blue solid print was applied to the inkjet recording medium with the above-mentioned ImagePROGRAF W8400, and the ink absorptivity was visually observed and evaluated by the following methods.
A: The ink absorption speed is very fast, and there is no wet feeling when discharged from the printer.
○: The ink absorption speed is fast, and there is no ink overflow or beading.
Δ: Some beading is recognized, but there is no practical problem.
X: Ink overflow and beading cause a practical problem.

[Smear]
The bleeding of the printing was visually evaluated from the printing boundary portion of the above ImagePROGRAF W8400.
(Double-circle): The blur of printing is not recognized at all and it is an excellent level.
○: There is a slight blur of printing, but there is no practical problem.
Δ: Level where printing is blurred and causes a practical problem.
X: The level at which printing blur is remarkable and becomes a serious problem in practical use.

<Example 1>
[Preparation of coating solution for ink solvent absorption delay layer]
Commercially available dispersant (manufactured by Toagosei Co., Ltd., trade name: Aron T-50) in water containing 0.2 parts kaolin (made by Imeris Minerals, trade name: Konzer 1500, average particle size 0.47 μm, aspect ratio 50- 60) After dispersing 100 parts, 3 parts of borax (sodium tetraborate decahydrate), 250 parts of styrene-butadiene copolymer latex (manufactured by Nippon Zeon Co., Ltd., trade name: LX407S12), and antifoaming agent, interface An auxiliary agent such as an activator was mixed and dispersed to finally prepare a coating liquid having a solid content concentration of 25%.

[Preparation of recording layer coating solution]
Commercially available dispersant (manufactured by Toagosei Co., Ltd., trade name: Aron T-50) Wet silica (manufactured by Tosoh Silica Co., Ltd., trade name: AY-603, average particle size 6.5 μm) as a pigment in 0.2 parts of water , 100 parts of oil absorption 250 ml / 100 g) and 28 parts of silanol-modified polyvinyl alcohol (trade name: R1130, manufactured by Kuraray Co., Ltd.) as a binder, and cationic resin: diallyldimethyl quaternary ammonium salt (trade name, manufactured by Senka Co., Ltd.) as an ink fixing agent. 30 parts of Unisense CP101) were mixed and dispersed to finally prepare a coating solution having a solid content of 15%.

[Preparation of inkjet recording material]
On one surface of woodfree paper having a basis weight of 100 g / m ^2, the ink solvent absorption delaying layer coating solution, coating by a bar coater so coating amount is 2.5 g / m ^2, and dried, the ink solvent absorption delaying layer The recording layer coating liquid was coated on a die coater so that the coating amount was 11 g / m ² and dried to prepare an ink jet recording material.

<Example 2>
An ink jet recording material was prepared in the same manner as in Example 1 except that in the preparation of the ink solvent absorption retardation layer coating liquid of Example 1, 300 parts of the styrene-butadiene copolymer latex was changed to 1000 parts.

<Example 3>
In the preparation of the ink solvent absorption retardation layer coating liquid of Example 1, kaolin (trade name: Konzer 1500) was changed to kaolin (product name: Astra Plus, average particle size 0.45 μm, aspect ratio 24). An ink jet recording material was produced in the same manner as in Example 1 except that the amount was changed to 100 parts.

<Example 4>
In the preparation of the ink solvent absorption retardation layer coating liquid of Example 1, kaolin (trade name: Konzer 1500) was changed to kaolin (product name: Astra Scene, average particle size 0.29 μm, aspect ratio 11). An ink jet recording material was produced in the same manner as in Example 1 except that the amount of the ink was changed to 100 parts.

<Example 5>
In the preparation of the ink solvent absorption delay layer coating liquid of Example 1, 300 parts of the styrene-butadiene copolymer latex was changed to 300 parts of an acrylic polymer (trade name: Primal P-376, manufactured by Rohm and Haas). Except for the above, an ink jet recording material was produced in the same manner as in Example 1.

<Example 6>
An ink jet recording material was prepared in the same manner as in Example 1 except that borax (sodium tetraborate decahydrate) was not included in the preparation of the ink solvent absorption retardation layer coating liquid of Example 1.

<Example 7>
An ink jet recording material was produced in the same manner as in Example 1 except that the coating amount of the ink solvent absorption delay layer was 1.0 g / m ² .
<Example 8>
An ink jet recording material was prepared in the same manner as in Example 1 except that the coating amount of the ink solvent absorption delay layer was 7.0 g / m ² and the recording layer coating amount was 30 g / m ² .
<Example 9>
An ink jet recording material was produced in the same manner as in Example 1 except that the coating amount of the ink solvent absorption delay layer was 1.5 g / m ² and the recording layer coating amount was 7.0 g / m ² .
<Example 10>
An ink jet recording material was produced in the same manner as in Example 1 except that the coating amount of the recording layer was 40 g / m ² .

<Example 11>
In the preparation of the recording layer coating liquid of Example 1, 100 parts of wet silica was changed to 100 parts of dry silica (manufactured by Degusa, trade name: AEROSIL-200, average primary particle diameter: 12 nm). Thus, an ink jet recording material was produced.

<Example 12>
In the preparation of the recording layer coating liquid of Example 1, 100 parts of wet silica was added to 100 parts of wet silica (manufactured by DSL Japan Co., Ltd., trade name: CARPLEX # 80, average particle size 15.0 μm, oil absorption 285 ml / 100 g). An ink jet recording material was produced in the same manner as in Example 1 except for the change.

<Example 13>
[Preparation of ink solvent absorption layer coating solution]
Commercially available dispersant (manufactured by Toagosei Co., Ltd., trade name: Aron T-50) wet silica as a pigment in water containing 0.2 parts (trade name: BY-400, trade name: BY-400, average particle size: 3.0 μm) , Oil absorption 210 ml / 100 g) 50 parts and kaolin (manufactured by Engelhard, trade name: Ultra White 90, average particle size 0.5 μm) 50 parts, PVA as a binder (trade name: PVA145, 15 parts), 30 parts of an acrylic polymer (manufactured by Meisei Chemical Co., Ltd., trade name: JK-7000, emulsion type binder) was mixed and dispersed to finally prepare a coating liquid having a solid content concentration of 25%.

An ink jet recording material was prepared in the same manner as in Example 1 except that the ink solvent absorption layer was applied between the ink solvent absorption delay layer and the recording layer with a die coater so that the coating amount was 10 g / m ² and dried. Produced.

<Comparative Example 1>
In the preparation of the ink solvent absorption retardation layer coating liquid of Example 1, 100 parts of kaolin (trade name: Contour 1500) was added to kaolin (trade name: New Surf, average particle size 2.0 μm, aspect ratio 16) 100 manufactured by BASF. An ink jet recording material was produced in the same manner as in Example 1 except that the part was changed to the part.

<Comparative example 2>
In the preparation of the ink solvent absorption retardation layer coating liquid of Example 1, 100 parts of kaolin (trade name: Contour 1500) was mixed with calcium carbonate (product name: Brilliant, average particle size 0.5 μm, aspect ratio 2). An ink jet recording material was produced in the same manner as in Example 1 except that the amount was changed to 100 parts.

<Comparative Example 3>
An ink jet recording material was prepared in the same manner as in Example 1 except that in the preparation of the ink solvent absorption retardation layer coating liquid of Example 1, 300 parts of the styrene-butadiene copolymer latex was changed to 80 parts.

<Comparative example 4>
An ink jet recording material was prepared in the same manner as in Example 1 except that 300 parts of the styrene-butadiene copolymer latex was changed to 2500 parts in the preparation of the ink solvent absorption delay layer coating liquid of Example 1.

<Comparative Example 5>
An ink jet recording material was prepared in the same manner as in Example 1 except that the ink solvent absorption delay layer was not provided.

<Comparative Example 6>
An ink jet recording material was produced in the same manner as in Example 1 except that the recording layer was not provided.

  As is apparent from Table 1, the ink jet recording material of the present invention suppresses cockling, does not bleed, has good ink absorbability, has high image density, has extremely good image uniformity, and is a paper at the time of cutting. It is an ink jet recording material excellent in both dyes and pigment inks that generate less powder.

  The ink jet recording body of the present invention can provide an ink jet recording body that suppresses cockling during printing or after printing, has no bleeding, has good ink absorbability, and generates a small amount of paper dust during cutting. It is extremely useful. In particular, it is possible to provide an ink jet recording material suitable for output in a large format ink jet plotter having a built-in cutter and suitable for output of a poster or a sign display.

Claims (4)

An ink recording medium having an ink solvent absorption delay layer and a recording layer on at least one surface of a support, wherein the ink solvent absorption delay layer provided between the support and the recording layer has an average particle size of 1.5 μm or less. An ink jet recording material comprising a flat pigment and a water-dispersible latex binder in a ratio of 100 to 2000 parts by weight of a water-dispersible latex binder with respect to 100 parts by weight of the flat pigment. The ink jet recording material according to claim 1, wherein the ink solvent absorption delay layer contains a crosslinking agent. Ink jet recording material according to claim 1 or 2 coating amount of the ink solvent absorption delaying layer is characterized in that it is a 1.5~6.0g / m ^2. The ink jet recording material according to any one of claims 1 to 3, wherein the flat pigment is kaolin.