JP2006212983A - Recording medium and recording method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium with good ink permeability and which can be printed at a high speed by a line head, and to provide a recording method wherein when the recording medium is recorded by using a monomer ink, there exists no possibility of clogging caused by solidification of the ink and an image with a high quality and high gloss is recorded. <P>SOLUTION: The recording medium is characterized by that an ink receiving layer containing a polymerization initiator is provided on a substrate, and the ink receiving layer is a porous layer containing an organic finely divided particle. The recording method is characterized by that the recording medium is printed by using the ink containing no polymerization initiator and comprising a polymerizable monomer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording medium and a recording method used for ink jet recording and the like, and more particularly to a recording medium having good ink permeability and capable of high-speed printing with a line head and a recording method using the same.

  The ink jet recording medium has characteristics such as high saturation of the formed image, the ability of the dye to be dyed firmly on the ink jet recording medium, quick drying and no ink bleeding. Required. Conventionally, as an ink jet recording medium for meeting these requirements, a void layer (ink receiving layer) is formed by applying a liquid containing inorganic fine particles and a water-soluble resin such as polyvinyl alcohol or gelatin to a support. Etc. are known (for example, refer to Patent Document 1).

Furthermore, an ink jet recording sheet has been proposed in which a coating layer containing porous resin particles having through holes is formed on a substrate (see, for example, Patent Document 2). Since the coating layer has a high porosity and uniform pores, the amount of ink absorbed per unit deposition in the surface portion is higher than that of a conventional recording sheet, and it is difficult for strikethrough to occur. It is said that it can handle higher resolution and higher speed printing.
However, if the ink jet recording sheet is also intended to be an ink receiving layer having good ink absorbability, it is necessary to keep the content of the water-soluble polymer in the porous particles low. There was a problem that the coating layer was peeled off from the support. Increasing the amount of the water-soluble polymer in order to suppress cracking causes a trade-off problem that the ink absorbability is lowered.

On the other hand, various inkjet recording inks such as water-soluble dyes, pigments, dispersed inks, UV inks, and solvents are known as ink-jet recording inks. Some pigment-based inks are also used.
In addition, when printing with water-soluble ink, pigment ink, and dispersed ink, increasing the pore diameter is an effective means to increase ink absorbency, but this reduces the glossiness of the surface. There was a problem. As a method for solving this, a method has been proposed in which a thermoplastic porous layer is formed, the pores are crushed by post-printing heat treatment, the surface smoothness is increased, and gloss is obtained (for example, Patent Document 3). ~ 5).
However, smoothing immediately after printing on the recording medium: heating and pressurizing (for example, a method of putting a smooth film on the printing surface and passing it through a heat roller) causes the ink itself to be insufficiently dried. There is a risk that the ink solvent will boil and foam when heated by the roller. When the ink evaporates after the smoothing treatment, since the pores of the foamed portion remain vacant, the light is scattered there and becomes haze, resulting in a decrease in density and saturation. Also, even when the foam is not foamed, if the pore diameter is larger than 0.3 μm, passing through the heat roller with the ink solvent clogged there will leave pores after drying without foaming. Similarly, haze is produced, and density and saturation are lowered.
In addition, since the ultraviolet curable ink itself contains a polymerizable monomer and a polymerization initiator, the viscosity gradually increases during storage or the polymer is solidified by heating with an inkjet head or exposure at the tip of the head. It was a cause of clogging.

In addition, an ultraviolet curable inkjet ink that does not contain a photopolymerization initiator and an inkjet receptive layer made of a photopolymerization initiator-containing ink are provided on a predetermined portion of the sheet substrate surface, and the ultraviolet curable inkjet is further formed on the inkjet receptive layer. There has been proposed a printing sheet on which printing printing is made of ink (see, for example, Patent Document 6).
However, this method solves the problem of clogging of the ink discharge nozzles, but it is extremely insufficient in terms of ink permeability and high-speed printability, and is not satisfactory in terms of glossiness of the print screen. There wasn't.
JP 10-119423 A JP-A-7-1835 JP-A-8-104056 JP 11-301108 A JP 2000-158803 A JP 2004-59810 A

  The present invention has been made on the basis of the above-described requirements, and an object of the present invention is to provide a recording medium having good ink permeability and capable of high-speed printing with a line head. It is another object of the present invention to provide a recording method for recording a high-quality and high-gloss image without clogging due to ink solidification when recording with a monomer ink on the recording medium.

<1> A recording medium having an ink receiving layer containing a polymerization initiator on a support, and the ink receiving layer is a porous layer containing organic fine particles.

<2> The recording medium according to <1>, wherein the polymerization initiator is a photopolymerization initiator and / or a thermal polymerization initiator.

<3> The recording medium according to <1> or <2>, wherein the porous layer has an average pore diameter of 0.01 to 10 μm.

<4> The recording medium according to any one of <1> to <3>, wherein the ink receiving layer is thermoplastic.

<5> The recording medium according to any one of <1> to <4>, wherein the organic fine particles are through-hole type particles.

<6> The recording medium according to any one of <1> to <5>, wherein the organic fine particles are styrene and / or allyl based particles.

<7> The recording medium according to any one of <1> to <6>, wherein the organic fine particles are organic fine particles having a positive charge and organic fine particles having a negative charge.

<8> The recording medium according to <7>, wherein at least one of the positively charged organic fine particles and the negatively charged organic fine particles is weakly charged.

<9> The recording medium according to any one of <1> to <8>, wherein the recording medium is for inkjet recording.

<10> A recording method comprising printing on the recording medium according to any one of <1> to <9> using an ink containing a polymerizable monomer without containing a polymerization initiator.

<11> The recording method according to <10>, wherein the recording medium after printing is further heated.

<12> The recording method according to <10>, wherein the recording medium after printing is further heated after light irradiation.

The present invention has been made on the basis of the above-described requirements, and an object of the present invention is to provide a recording medium having good ink permeability and capable of high-speed printing with a line head.
Furthermore, according to the present invention, a recording method for recording a high-quality and high-gloss image without clogging due to ink solidification, as seen in ultraviolet curable inks, when recording with a monomer ink on the recording medium. Can provide.

[recoding media]
The recording medium of the present invention has an ink receiving layer containing a polymerization initiator on a support, and the ink receiving layer is a porous layer containing organic fine particles.
In the recording medium of the present invention, when the ink receiving layer is a porous layer containing a polymerization initiator and containing organic fine particles, the ink permeability is improved, and a polymerizable monomer ink is used. Can suppress ink solidification by heating with a heat roller.
In the recording method of the present invention, the ink when recording (for example, inkjet) on the recording medium of the present invention is a polymerizable monomer ink, but the polymerizable monomer ink does not contain a polymerization initiator. And
Therefore, no polymerization reaction occurs during ink storage, and no head clogging occurs.
When printing is performed on the recording medium of the present invention using the polymerizable monomer ink, the polymerizable monomer ink penetrates into the ink receiving layer and coexists with the polymerization initiator contained in the ink receiving layer. .
When the polymerization initiator is a thermal polymerization initiator, in that state, for example, by superposing a heat-resistant film or the like on the printing surface and passing it through a heat roller, thermal polymerization occurs immediately, the ink is cured, and porous pores are formed. Simultaneously, the thermoplastic porous surface is smoothed and gloss is imparted.
When the polymerization initiator is a photopolymerization initiator, light irradiation (especially ultraviolet irradiation) is performed immediately after printing, and then a heat-resistant film or the like is superimposed on the printing surface and passed through a heat roller, or on the printing surface immediately after printing. Overlaying heat-resistant films, etc., passing them through a heat roller, and subsequently irradiating with light, photo / thermal polymerization occurs, the ink hardens, the porous pores are closed, and at the same time, the thermoplastic porous surface is smoothed. , Gloss is imparted.

≪Ink receiving layer≫
The ink receiving layer is a porous layer containing organic fine particles, and even with a pigment-based ink, the ink permeability is high and high-speed printing is possible, so the average pore diameter of the porous layer is 0.01 to 10 μm. Is preferable, 0.05 to 5 μm is more preferable, and 0.1 to 3 μm is particularly preferable. If it is smaller than 0.01 μm, the ink absorbability may be deteriorated, and if it is larger than 10 μm, the sharpness of the image may be lowered. By setting the average pore diameter within the range, both high image quality and high-speed printability can be achieved.
The layer thickness of the ink receiving layer is preferably 1 to 100 μm, more preferably 5 to 90 μm, and particularly preferably 10 to 80 μm.

The “average pore diameter” in the present invention is the mercury intrusion method proposed by Washburn (“Surface”, Vol. 13, No. 10, p. 588, “Pore distribution measurement method of porous material” , Equipment and problems (1) ”). As a measuring device, a mercury porosimeter (trade name “Pore Sizer 9320-PC2” manufactured by Shimadzu Corporation) is used.
In addition, when the ink receiving layer (porous layer) in the present invention is formed on a paper support or the like by coating and the measurement by the mercury intrusion method cannot be performed accurately, the scanning electron of the cross section (section) of the recording medium is used. After taking micrographs at multiple magnifications and digitizing them with the scanner input method, the average diameter (calculated from the distribution of diameters of circles with the same area as the area of each void extracted by computer image analysis) (Number average) was defined as the average pore diameter.

The ink receiving layer (porous layer) preferably has thermoplasticity. In the present invention, “thermoplastic” means a property that an object becomes soft and easily deforms at a certain temperature or higher, and usually has a glass transition point of 150 ° C. or lower, preferably 120 ° C. or lower, particularly preferably 110 ° C. or lower. is there. By imparting thermoplasticity to the ink receiving layer (porous layer), the printed screen after image printing can be easily smoothed, and the gloss of the image can be greatly improved by this smoothing.
Further, as described above, in order for the ink receiving layer (porous layer) to be thermoplastic, at least 30% by mass, more preferably 50% by mass or more, particularly preferably 65% by mass, of the composition forming the layer. % Or more of the material is desirably thermoplastic.
As the organic fine particles in the ink receiving layer (porous layer), it is preferable that at least one of the organic fine particles is thermoplastic. In the case of having a plurality of these, it is more preferable that more organic fine particles are thermoplastic. Even when all organic fine particles do not have thermoplasticity, the thermoplasticity can be reduced by adding a thermoplastic binder resin (preferably in the form of particles) having the following low glass transition temperature to the ink receiving layer (porous layer). Can be granted.

Furthermore, 50 mass% or more, preferably 80 mass% or more of the thermoplastic binder resin (hereinafter also referred to as “thermoplastic substance”) has a glass transition temperature (Tg) of 25 to 150 ° C., preferably 40 to 40%. 130 degreeC, Most preferably, it is 50-120 degreeC.
When the Tg is lower than 25 ° C., the porosity is not sufficient, and the porosity decreases during storage of the ink jet recording medium, or blocking failure occurs. On the other hand, when Tg is higher than 150 ° C., the porous layer is fragile and smoothing after printing is not performed well.

<Organic fine particles>
Next, the organic fine particles in the present invention will be described.
Examples of the organic fine particles include fine particles made of polyethylene, polypropylene, various acrylic resins, polyurethane resins, polyester resins, polystyrene resins, etc. Among them, styrene and / or acrylic particles are preferable.
The organic fine particles are preferably through-hole-type particles and / or organic fine particles having two kinds of opposite charges of positively charged organic fine particles and negatively charged organic fine particles.

(Through-hole type particles)
Hereinafter, the through-hole type particles in the present invention will be described.
The through-hole type particle is a particle having a hole penetrating from one surface (area) to another surface (area). By forming through-hole type particles in the ink receiving layer, the ink can be absorbed (accommodated) not only in the voids between the particles but also in the through holes, so that the ink absorption as a whole of the ink receiving layer is achieved. Improves.
Since the surface of the through-hole type particle has a hydrophobic or hydrophobic portion, it is estimated that the permeability of the solvent-based ink and the UV ink is good.

  The through-hole type particles are used by being dispersed in an aqueous coating solution together with an aqueous binder. At this time, examples of the surfactant used as the dispersant include those described in the following specification or publication. That is, U.S. Pat.Nos. 2,240,469, 2,240,470, 2,240,471, 2,240,472, 2,240,475, 2,240,476, 2,235,279, 2719087, 2,379,891, 2,801,191, 2,813,123, 2,843,487, 3,003877 No. 3026202, No. 30308804, No. 30411804, No. 30308804, No. 30411171, No. 3068101, No. 3165409, No. 3169870, No. 3201252, No. 3320847, No. 3306749, No. 3408193, No. 3425857 3437485, 3502473, 3506449, 3514293, 3539352, 564576, 3573049, 360 291, the 3,775,126 Patent, the 3,850,640 Patent, the 3,909,272 Patent, the 887,012 JP,

U.S. Application Nos. 230519, 442794, 480101, 515179, 515179, 580872, British Patent Nos. 774806, 867842, 874081, 1186866, Japanese Patent Publication Nos. 43-10247 and 43- No. 13481, No. 43-24722, No. 44-22659, No. 45-38945, No. 46-21985, No. 49-16051, JP-A-48-43924, No. 49-37623, No. 50- No. 46133, No. 51-7917, No. 53-21922, No. 53-49427, No. 54-98235, No. 51-3219, JP-B-39-18702, No. 40-376, No. 40-1701 Nos. 40-23747, 43-13166, 43-17922, 44-22661, 45-3830, 45-334767, 46-21183, 46-25594, 46-3191, 46-43428, 47-4639, 47-5318, 47-15801 No., Japanese Patent Application No.42-58329,

British Patent Nos. 1039183, 1178546, 1301828, 1320880, 1336164, 1336172, 1344987, 1345533, West German Patent Nos. 11717138, 1186743, Belgian Patent No. 609782, 543287, U.S. Pat.Nos. 3,422,222, 3,113,816, 3,442,654, 3,516,835, 3,563,756, 3,617,292, 3,619,199, 3725079, 3,725,680, U.S. Application Nos. 5,505,453, 5,792,213 U.S. Pat.Nos. 3,493,379, 3,416,923, 3,542,581, 3,619,195, 3,963,688, JP-A-47-23378, 48-9979, 48-3093 Nos., The same 50-66230 JP, same 50-80119 JP, same 51-25133 JP, same 53-138726 JP, same 50-34233 JP, JP-A-41-72675,

British Patent Nos. 1344425, 1344426, 1498697, West German Patent Nos. 1772129, 20496589, 1201136, 1597492, U.S. Patent Nos. 3,565,625, 3,679,411, 2,848,330, 2,940,851, No. 2944900, No. 2944902, No. 3017271, No. 3061437, No. 3062647, No. 3068102, No. 3318183, No. 3434833, No. 3523023, No. 3706562, No. 3869289, No. 49-33788, 53-12380, 53-15581, Belgian Patent No. 61864, West German Patent No. 1151437, No. 1472790, No. 1772315, No. 1816570, No. 1816572 2845907, British Patent Nos. 1351498, 1326358, 1455413, 1456359, 1488899, 1212312, British Patent Nos. 3084044, 3113026, 2937087, Japanese Patent Application Laid-Open No. Sho 47- 42001, 49-55335, 50-156423, 53-44025, 49-24427,

British Patent No. 1491902, Japanese Patent Laid-Open Nos. 48-23436, 48-63735, 48-94433, 50-57437, U.S. Patent Nos. 3062654, 3093479, 3396028, 3743504, Research Disclosure No. 17643 (December 1978), Japanese Patent Publication Nos. 45-6629, 47-41833, 49-4530, 54-15571, 54-17732, 54-89624, Japanese Patent Publication 45-6630 No. 47-4417, No. 47-15801, No. 48-34166, No. 50-40660, No. 51-848, West German Patent No. 1202136, No. 1447585, No. 1472274, No. 2641284, 22031116, Belgian Patents 605378, 622859, 631905, 631557, British Patents 1327032, 1358848, U.S. Pat.Nos. 3,597,214, 3,615,612, 3,493,379, 3,798,265,

Research Disclosure No. 11666 (December 1973), U.S. Pat. No. 57-104925, 58-86540, 58-90633, 56-81841, 53-138726, European Patents 19800, 153133, 60-203935, 60- No. 200251, No. 60-209732, and the like.

  Preferred specific example compounds are illustrated below.

  The volume average particle diameter of the through-hole type particles is preferably 0.1 to 10 μm, and more preferably 0.2 to 7 μm. Here, the volume average particle diameter of the through-hole type particles is a numerical value measured by a laser diffraction / scattering particle diameter measuring apparatus LA-910 (manufactured by Horiba, Ltd.).

Further, the diameter of the through hole is preferably 1/100 to 1/2 of the volume average particle diameter, preferably 1/30 to 1/2, and more preferably 1/10 to 1/2. Is more preferable.
As a specific example of such a through-hole type particle, a styrene type and / or an acrylic type is preferable. Specific preferred examples include Mutile PP-2000TX (styrene / acrylic) manufactured by Mitsui Chemicals. These may be used alone or in combination of two or more.
The through-hole type particles can be produced, for example, by the methods described in JP-A-5-222108 and JP-A-5-112606. The through-hole type particles are preferably thermoplastic in order to express the sharpness and glossiness of an image by a smoothing process performed after printing.

Hereinafter, the organic fine particles having a positive charge and the organic fine particles having a negative charge in the present invention will be described.
(Organic fine particles with positive charge)
The organic fine particles having a positive charge have a charge on the particle surface. For example, the primary or tertiary amino group, imino group, or a salt thereof (hydrochloride, etc.) or quaternary in the main chain or side chain. Examples include polyurethane-based, polyester-based, polyacrylate-based, polymethacrylate-based, polystyrene-based fine particles having cationic groups such as ammonium base and pyridinium base.
The content of the polymerizable monomer unit having a cationic group such as a primary to tertiary amino group, an imino group, or a salt thereof, a quaternary ammonium base, or a pyridinium base in the polymer constituting the organic fine particle is 0. 0.1 to 100 mol%, preferably 0.5 to 50 mol%, particularly preferably 1 to 30 mol%.
The weight average molecular weight (Mw) of the polymer is suitably about 3,000 to 100,000, and preferably about 5,000 to 50,000.
As the organic fine particles having a positive charge on the surface, thermoplastic organic fine particles are preferably used.
By making the positively charged organic fine particles thermoplastic, it becomes easy to impart thermoplasticity to the ink receiving layer, and smoothing processing after printing is also easily performed.

  As the thermoplastic polymer fine particles having a positive charge on the surface, for example, a dispersion of a polymer having a positive charge can be used. As such a dispersion, a (co) polymer dispersion containing monomer units described in paragraphs 0018 to 0032 of JP-A-9-114066 can be used. The monomer units a), b) and c) constituting the (co) polymer are represented by the following general formula (1).

In general formula (1), A in monomer unit a) has at least two copolymerizable ethylenically unsaturated groups and is copolymerized with a copolymerizable monomer so that at least one of them is contained in the side chain. Represents a monomer unit. B in the monomer unit b) represents a monomer unit obtained by copolymerizing a copolymerizable ethylenically unsaturated monomer. In the monomer unit c), R ₁ represents a hydrogen atom, a lower alkyl group (1 to 6 carbon atoms) or an aralkyl group (7 to 12 carbon atoms). Q is a divalent linking group, for example, an alkylene group (1 to 12 carbon atoms), a phenylene group, an aralkylene group (7 to 12 carbon atoms), -COO-L-, -CONH-L-, -CONR-L. -Represents a group represented by-. Here, L represents an alkylene group (1 to 6 carbon atoms), an arylene group (6 to 12 carbon atoms) or an aralkylene group (7 to 12 carbon atoms), and R represents an alkyl group (1 to 6 carbon atoms).

G represents the following structural formula (A), and R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ and R ₉ are each independently a hydrogen atom or an alkyl group (having 1 to 12 carbon atoms). Represents an aryl group (6 to 20 carbon atoms) or an aralkyl group (7 to 20 carbon atoms), which may be the same as or different from each other, and may be substituted. X represents an anion. In addition, any two or more groups of Q, R ₂ , R ₃ , R ₄ or Q, R ₅ , R ₆ , R ₇ , R ₈ , R ₉ are bonded to each other to form a ring structure together with the nitrogen atom. It may be formed.

Examples of the monomer in A include divinylbenzene and ethylene glycol dimethacrylate as well as those described in paragraph 0018 of the above publication.
Examples of the ethylenically unsaturated monomer in B include styrene, n-butyl methacrylate, methyl methacrylate, and those described in paragraphs 0019 to 0021 of the above publication.

R ₁ is preferably a hydrogen atom or a methyl group, and those described in paragraph 0022 of the above publication, and Q is preferably an alkylene group such as —CH ₂ — or — (CH ₂ ) ₆ —; In addition to a phenylene group and a p-phenylenemethylene group, those described in paragraph 0022 of the above publication can be mentioned.

Examples of the alkyl group represented by R ₂ to R ₉ in the structural formula (A) include a methyl group, an ethyl group, and an n-propyl group, and those described in paragraph 0027 of the above publication, and an aryl group includes a phenyl group. In addition to the naphthyl group, those described in paragraph 0028 of the above publication can be mentioned, and examples of the aralkyl group include those described in paragraph 0029 of the above publication in addition to the benzyl group and phenethyl group. Examples of X include chloride ions, acetate ions, sulfate ions, and those described in paragraph 0030 of the above publication.

  The (co) polymer contains at least monomer unit c), and its content is 0.1 to 100 mol%, preferably 0.5 to 50 mol%, particularly preferably 1 to 30 mol%. . Moreover, when the said copolymer contains the monomer unit represented by A, the content is 1-20 mol%, and when the monomer unit represented by B is contained, the content is 0.1-99. 9 mol%.

  Specific examples of the polymer represented by the general formula (1) include, in addition to the copolymers from P-1 to P-23 described in paragraphs 0037 to 0041 of the publication, moles of the copolymer monomer. What changed ratio suitably can be used.

  Further, as a dispersion of a thermoplastic polymer having a positive charge, the basic latex described in JP-B-62-1678, page 3, column 6, line 5 to page 9, column 18, line 5, JP-A-5-306314 No. 2, page 2, column 28 to page 4, column 5, line 1 and JP-A-9-99632, page 3, column 3, line 6 to page 4, column 6, line 41, JP-A-11-348416. 6 page 9 column 33 line 7-7 page 12 column 3 line WO00 / 6390 page 24 12 line 27-page 9 line 3 page 4 column 2 of JP-A-2001-106732. Line 5-5 page 8 column 40 line, JP 2002-67495, page 4, 6 column 23 line 11 page 19, column 19 line 47, JP 2002-172854 page 8, 14 column 33 JP-A-2002-225414 described in line 10 to page 10, column 18, line 20. Japanese Patent Laid-Open No. 5, page 8, line 45 to page 6, column 9, line 23, Japanese Patent Laid-Open No. 2002-292993, page 3, column 3, line 3 to page 4, column 6, line 2, and JP 2002-347338. Each cationic polymer fine particle described in page 18, column 33, line 24 to column 35, line 35 of the publication can be used.

When a hydrophobic group of a polymerizable monomer having a hydrophobic group, for example, an alkyl group, an aryl group, an aralkyl group, or the like appears on the surface of the polymer fine particles, cross-linking aggregation is more likely to occur. The fine particles having a hydrophobic group appearing on the surface are at least one of R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ of the monomer unit c). Specifically, one having 4 or more carbon atoms is an alkyl group, aryl group or aralkyl group.

(Organic fine particles with negative charge)
The organic fine particles having a negative charge include a —COOH group, —SO ₃ H group, —SO ₄ H group, —SO ₂ H group, —PO ₄ H group or a salt thereof (alkali metal salt, NH ₄ ⁺ Salt, quaternary ammonium salt, etc.) and other thermoplastic polymer fine particles having an anionic group, for example, polyurethane-based, polyester-based, polyacrylate-based, polymethacrylate-based, polystyrene-based having an anionic group. And fine particles of the polymer.
It is preferable to use thermoplastic organic fine particles as the organic fine particles having a negative charge on the surface.

As the thermoplastic polymer fine particles having a negative charge on the surface, for example, a polymer dispersion having a negative charge can be used.
Examples of the negatively charged polymer include polymers from polymerizable monomers having an anionic group as described above. Examples of the polymerizable monomer having an anionic group include α, β-ethylenically unsaturated monocarboxylic acid, α, β-ethylenically unsaturated dicarboxylic acid or monoalkyl ester thereof (alkyl group having 1 to 12 carbon atoms). Or a polymer obtained by polymerizing a monomer in which an anionic group is substituted on the alkyl group of the alkyl ester moiety. Further, the monomers include those in which the N atom of the monoamide of α, β-ethylenically unsaturated dicarboxylic acid is substituted with an anionic group-substituted alkyl group (alkyl group having 1 to 12 carbon atoms). Examples of the α, β-ethylenically unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid, and examples of the α, β-ethylenically unsaturated dicarboxylic acid include maleic acid and fumaric acid.
In addition, a monomer in which an anionic group is substituted for styrene (phenyl substitution, β-position substitution) is also used.

  A copolymer obtained by copolymerizing another monomer with the anionic group-containing monomer is preferably used. Examples of the other monomer include α, β-ethylenically unsaturated monocarboxylic acid alkyl ester (alkyl group having 1 to 12 carbon atoms). , Α, β-ethylenically unsaturated dicarboxylic acid dialkyl ester (alkyl group having 1 to 12 carbon atoms), styrene, divinylbenzene, vinyl ether, vinyl thioether, vinyl halide and the like. Examples of the α, β-ethylenic unsaturation include acrylic acid, methacrylic acid, and croton, and examples of the α, β-ethylenically unsaturated dicarboxylic acid include maleic acid and fumaric acid.

Specific examples of the copolymer include those described in JP-A-62-215272, pages 231 to 239, and on page 239, E-4, E-11 to E-19, E-20. In addition to the anionic group-containing copolymers mentioned as E-22 and E-23, those obtained by appropriately changing the molar ratio of the copolymer monomers can be used.
The content of the anionic group-containing polymerizable monomer unit in the polymer constituting the fine particles is 0.1 to 100 mol%, preferably 0.5 to 50 mol%, particularly preferably 1 to 30 mol%.
Further, as thermoplastic polymer fine particles having a negative charge on the surface, JP-A-6-266040, page 6, column 9, line 6 to page 9, column 15, line 25, JP-A 2002-365767, page 4, column 5. Examples include those described in line 22 to page 5, column 7, line 1, and JP-A 2003-94597, page 7, column 11, line 23 to page 8, column 14, line 9.

When a hydrophobic group from a polymerizable monomer having a hydrophobic group, for example, an alkyl group, an aryl group, an aralkyl group, or the like appears on the surface of the polymer fine particle, cross-linking aggregation is more likely to occur. Specifically, the fine particles having a hydrophobic group appearing on the surface include a polymerizable monomer having an alkyl group, aryl group or aralkyl group having 4 or more carbon atoms in a polymerizable monomer unit having an anionic group. Examples thereof include polymer fine particles obtained by polymerizing monomers.
Further, the weight average molecular weight (Mw) of the negatively charged polymer is suitably about 3,000 to 100,000, and preferably about 5,000 to 50,000.

The volume average particle diameter of the organic fine particles having a positive charge or a negative charge in the present invention is 0.01 to 20 μm, preferably 0.02 to 10 μm, and more preferably 0.05 to 5 μm. The volume average particle diameter is obtained by measuring with a scanning electron micrograph.
The shape of the polymer fine particles may be any of spherical shape, needle shape, flat plate shape, erythrocyte shape, through-hole shape, confetti shape, etc., and through-hole-like fine particles are particularly preferable. The dispersion diameter is measured by measuring with a scanning electron micrograph.
Further, the ratio of the organic fine particles to the water-soluble polymer described later is appropriately about 75:25 to 99: 1, preferably 80:20 to 98: 2, more preferably 85:15 to 97: 3. It is.

The coating liquid for forming the ink receiving layer (porous layer) in the present invention will be described.
The coating liquid used in the present invention contains organic fine particles. When the organic fine particles contain positively charged organic fine particles and negatively charged organic fine particles on the surface, at least one of them is preferably weakly charged. When organic fine particles having at least one of weakly charged properties are used, it is possible to easily achieve both coating suitability and cross-linking aggregation properties described below.
The coating solution may appropriately contain other components described later.

When the porous layer in the recording medium of the present invention is formed from organic fine particles consisting of only two types of organic fine particles having opposite charges, they are formed by cross-linking and aggregation. It is more likely that the positive and negative charge numbers are about the same. However, if too much emphasis is placed on cross-linking aggregation, the viscosity of the coating solution increases or sedimentation occurs, making it unsuitable for coating (excessive cross-linking aggregation occurs in the coating solution). It is difficult to produce a good porous layer. Therefore, in the coating liquid in the present invention, at least one of the organic fine particles having a charge on the surface and the organic fine particles having a charge opposite to the charge of the organic fine particles is made weakly charged, and the pH of the coating liquid or the coating liquid is applied. It is preferable to adjust both the coating property and the cross-linking aggregation property by adjusting the pH of the coating layer formed.
The use ratio of the organic fine particles having positive charge and the organic fine particles having negative charge is preferably 95: 5 to 5:95, and more preferably 95: 5 to 60:40, It is particularly preferable that the ratio is 95: 5 to 70:30.

That is, the anionic group or the cationic group having a weak charge property changes its charge state at a certain pH region. For example, in the case of a —COOH group, it is difficult to dissociate in a low pH range, but when the pH is increased and exceeds a certain pH range, COO ⁻ ions increase in the aqueous medium. On the other hand, when a quaternary salt ammonium group or the like is used as a cationic group, the number of cations of this group hardly changes depending on pH. By utilizing these properties, the pH of the coating solution is adjusted to control the amount of COO ⁻ ions, and the balance between coating suitability and cross-linking aggregation characteristics can be achieved (first method below). Optimize coating properties by adjusting the pH of the coating solution so that the amount of COO ⁻ ions is reduced, and add an alkaline pH adjuster to the coating layer after coating to increase COO ⁻ ions and optimize cross-linking aggregation characteristics (hereinafter referred to as “coating properties”). The second method).
By utilizing the above method, it becomes possible to optimize the viscosity of the coating solution in the first and second methods and to prevent precipitation in the coating solution. The viscosity of the coating solution is preferably 10 to 500 mPa · s, more preferably 20 to 300 mPa · s, and particularly preferably 30 to 250 mPa · s.

In the present invention, the organic fine particles are weakly charged when the organic fine particles have a chargeable group, that is, an anionic group or a cationic group, dissolved or dispersed in the aqueous medium. This means that the dissociation does not increase unless the aqueous medium is adjusted to a specific pH range. Strongly charged means that the dissociation is large regardless of the pH of the aqueous medium (dissociation constant of 10 ⁻³ or more). .

Among the anionic group, -COOH group, -PO ₄ H ₂ groups or their salts and the like, an anionic group having a weakly charged (weakly anionic group), also, the one of the cationic groups A primary group, a secondary group, a tertiary amino group, an imino group, or a salt thereof is a cationic group having a weak charge (weakly cationic group). (As the anionic group having a strong charge (strong anionic group), a —SO ₃ H group, a —SO ₄ H group, a —SO ₂ H group, or a salt thereof may be used. (Examples of the functional group (strong cationic group) include quaternary ammonium bases and pyridinium bases.)

Examples of combinations in the case where organic charged fine particles at least one of which is weakly charged in the present invention include the following.
1) Combination of weak anionic fine particles / strong cationic fine particles (eg, combination of -COOH group-containing fine particles / quaternary ammonium base-containing fine particles)
2) The combination of weakly cationic microparticles / strong anionic fine particles (eg-NH. ₂ group-containing microparticles / -SO ₃ ^- combination of group-containing fine particles)
3) Combination of weak anionic fine particles / weak cationic fine particles (eg, -COOH group-containing fine particles / -NH ₂ group-containing fine particles)

<Polymerization initiator>
The ink receiving layer in the invention is characterized by containing an unreacted polymerization initiator.
By adding the polymerization initiator to the ink receiving layer, when recording using a monomer ink containing a polymerizable monomer in the ink, a polymerization reaction is started by heat and / or light, and the ink Since it solidifies immediately in or on the ink receiving layer, there is no foaming or boiling in the ink receiving layer, which is a conventional problem, and polymerization solidification due to heating in the ink jet head seen in UV ink occurs. In addition, high-speed printing with a line head is possible.
Examples of the polymerization initiator in the present invention include a photopolymerization initiator system and a thermal polymerization initiator system.

(Photopolymerization initiator)
Hereinafter, the photopolymerization initiator will be described.
Examples of the photopolymerization initiator to be contained in the ink receiving layer include substantially all known compounds.
The photopolymerization initiator used in the present invention refers to a compound that generates active radical species or cationic species by applying active light and initiates and accelerates the polymerization reaction of the binder. Ultraviolet rays are preferred as the active light. In addition, known as active energy rays, gamma rays, alpha rays, electron rays, and the like can be used instead of active rays.

  Examples of the polymerization initiator that generates radicals by the action of light are preferably acetophenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds, benzyl compounds, acylphosphine oxide compounds, and the like.

  Examples of the acetophenone compound include 2,2-diethoxyacetophenone, 2-hydroxymethyl-1-phenylpropan-1-one, 4′-isopropyl-2-hydroxy-2-methyl-propiophenone, 2-hydroxy -2-methyl-propiophenone, p-dimethylaminoacetone, p-tert-butyldichloroacetophenone, p-tert-butyltrichloroacetophenone, p-azidobenzalacetophenone, 1-hydroxycyclohexyl phenyl ketone and the like.

  Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, and benzyldimethyl ketal.

  Examples of the benzophenone compounds include benzophenone, methyl o-benzoylbenzoate, Michler's ketone, 4,4'-bisdiethylaminobenzophenone, 4,4'-dichlorobenzophenone, and the like.

  Examples of the thioxanthone compound include thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-inopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, and the like.

Examples of the benzyl compound include benzyl and benzyl-β-methoxyethyl acetal.
Examples of the acyl phosphine oxide compound include bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and the like.

  A water-soluble polymerization initiator is preferably used in the present invention. Examples of water-soluble polymerization initiators include sodium-1- (sulfomethyl) benzophenone, (4-benzoylbenzyl) -trimethylammonium chloride, sodium-4- (sulfomethyl) benzyl, 4- (trimethylammoniummethyl) benzyl bromide, 2-carboxy. -Methoxy-thioxanthone N (2-hydroxyethyl) -N, N-dimethylammonium salt, sodium-2- (3-sulfopropoxy) thioxanthone, and the like.

  Since the sulfonium salt and iodonium salt, which are usually used as photocation generators described below, act as radical generators upon irradiation with ultraviolet rays, these may be used alone in the present invention. In addition to a polymerization initiator, a sensitizer may be used for the purpose of increasing sensitivity. Examples of the sensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, and thioxanthone derivatives.

  As a photopolymerization initiator that generates an active cationic species by ultraviolet rays, an onium salt initiator such as an aromatic iodonium salt such as a triarylsulfonium salt or an aromatic iodonium salt such as a diaryliodonium salt is useful. Nonionic initiators such as nitrobenzyl esters can also be used. Among these, aromatic sulfonium salts and the like are preferable because they are relatively stable thermally. In addition, known photopolymerization initiators described in “Organic Materials for Imaging” published by Organic Electronics Materials Research Group (published in 1997), etc. can also be used.

When an aromatic sulfonium salt and an aromatic iodonium salt are used as an onium salt photoinitiator, the counter anions include BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , PF ₆ −, B (C ₆ F ₅ ) _4- ^{and the} like. As the initiator, PF ₆ salt or SbF ₆ salt of aromatic sulfonium can be preferably used since it has solubility and moderate polymerization activity. In order to improve solubility, one or more alkyl groups or alkoxy groups having 1 to 10 carbon atoms are introduced into the aromatic group, usually phenyl group, of the aromatic group iodonium salt or aromatic sulfonium salt. A chemical structure is preferred.
PF ₆ salt or SbF ₆ salt of aromatic sulfonium salt is commercially available from Union Carbide Japan Co., Ltd. Asahi Denka Kogyo Co., Ltd. also sells PF ₆ salt of aromatic sulfonium under the trade name of Adekaoptomer SP series.
The aromatic sulfonium salt has an absorption up to about 360 nm, and the aromatic iodonium salt has an absorption up to about 320 nm. Therefore, for curing, it is preferable to irradiate ultraviolet rays including the spectral energy in this region.

(Sensitizer)
The sensitizer alone is not activated by light irradiation, but when used together with a photopolymerization initiator, a sensitizer that is more effective than the photopolymerization initiator used alone can be used. Kind is used. The addition of amines increases the curing rate, primarily because hydrogen is supplied to the photopolymerization initiator by the action of hydrogen abstraction, and secondly, the generated radicals are combined with oxygen molecules in the atmosphere and are reactive. This is because the amine has an action of trapping oxygen dissolved in the composition.

Sensitizers include amine compounds (aliphatic amines, amines containing aromatic groups, piperidine, reaction products of epoxy resins and amines, triethanolamine triacrylate, etc.), urea compounds (allylthiourea, o-tolylthio). Urea), sulfur compounds (sodium diethyl dithiophosphate, soluble salts of aromatic sulfinic acid, etc.), nitrile compounds (N, N-diethyl-p-aminobenzonitrile, etc.), phosphorus compounds (tri-n-butylphosphine, Sodium diethyldithiophosphide, etc.), nitrogen compounds (Michler ketone, N-nitrisohydroxylamine derivatives, oxazolidine compounds, tetrahydro-1,3-oxazine compounds, formaldehyde or condensates of acetaldehyde and diamines), chlorine compounds (carbon tetrachloride) , F Sa chloroethane, etc.), and the like.
The sensitizer can be contained in the ink receiving layer, but is preferably contained in the ink.

  The usage-amount of a sensitizer is 0-10 mass% normally, 0.1-10 mass% is preferable and 0.2-5 mass% is especially preferable. The selection and combination of the photoinitiator and the sensitizer, and the blending ratio may be appropriately selected depending on the ultraviolet curing monomer used and the apparatus used.

(Thermal polymerization initiator)
As the thermal polymerization initiator, a radical polymerization initiator generally used for a polymer synthesis reaction by radical polymerization can be preferably used. These radical polymerization initiators include the following.

(1) Azobisnitrile compounds 2,2′-azobisisobutyronitrile, 2,2′-azobispropionitrile, 2,2′-azobisvaleronitrile, and the like.

(2) Organic peroxides benzoyl peroxide, lauroyl peroxide, acetyl peroxide, tert-butyl perbenzoate, α-cumyl hydroperoxide, di-t-butyl peroxide, diisopropyl peroxydicarbonate, t -Butyl peroxyisopropyl carbonate, peracids, alkyl peroxycarbamates, nitrosoaryl acylamines and the like.

(3) Examples of the inorganic peroxide include inorganic peroxides such as potassium persulfate, ammonium persulfate, and potassium perchlorate.

(4) Others Tetraalkylthiuram disulfides such as nitrosophenylurea and tetramethylthiuram disulfide, diaryl disulfides such as dibenzoyl disulfide, tetraalkylthiuram monosulfides, dialkylxanthogenic disulfides, arylsulfinic acids, arylalkylsulfones , 1-alkansulfinic acids and the like.
As for these thermal polymerization initiators, for example, edited by the Society of Polymer Science, Japan: Polymer Engineering Course 1, “Chemistry of Polymers”, pages 162-181 (Jinjinshokan, 1968), Niji Uno: Polymer Engineering Course 10 “ Polymerization and Depolymerization ”, pages 146-147 (Kyoritsu Shuppan, 1961), Takayuki Otsu: Chemical Supplement 7“ Synthesis of Polymers ”, pages 14-16 (Chemical Doujin, 1961), Sugimura et al .: Journal of Synthetic Organic Chemistry 24, 373-390 (1966). The thermal polymerization initiator is preferably selected depending on the type of polymer contained in the ink receiving layer.
When the polymerization initiator is oil-soluble, it is preferably dissolved in a low-boiling and / or high-boiling organic solvent, emulsified and dispersed in an aqueous medium, and added to the aqueous coating solution.
The addition amount of the ink receiving layer of the thermal polymerization or photopolymerization initiator is preferably 1μmol~20mmol / m ^2, more preferably ^{0.005mmol~5mmol / m 2, 0.01mmol~2mmol / m} 2 is particularly preferred.

In addition, inorganic charged fine particles can be added to the porous layer in the present invention within a range not exceeding 50% by volume of the layer.
Examples of the inorganic fine particles having a positive charge on the surface include fine particles composed of zinc oxide, magnesium oxide, zirconium oxide, aluminum oxide, aluminum hydroxide and the like. Further, fine particles having a neutral or negative charge on the surface (for example, silica fine particles, calcium carbonate fine particles, barium sulfate fine particles, etc.) are surfaced by polyvalent metal ions such as aluminum, quaternary salt compounds, or primary to tertiary amino groups. By modifying or substituting the surface, it can be used as fine particles having a positive charge on the surface.
Furthermore, as the inorganic fine particles having a positive charge, layered (tabular) particles having a positive charge on the surface, such as hydrotalcite, can be used. The average particle size of the layered (tabular) particles is 0.1 to 30 μm, preferably 0.2 to 20 μm, particularly preferably 0.5 to 10 μm, and the aspect ratio is 3 to 1000, preferably 4 to 500, particularly preferably 5 to 300.

Examples of the inorganic fine particles having a negative charge on the surface include silica fine particles. Further, even if the surface has a neutral or positively charged, -COO ^- group, -SO ₃ ^- by surface modification or surface replacement with a compound having a group, be a particulate remembering negatively charged surface Can do.

As inorganic fine particles having a negative charge on the surface, layered (tabular) particles such as swellable synthetic mica (such as Somasif ME100 manufactured by Corp Chemical Co.), non-swellable mica (such as Somasif MK100 manufactured by Corp Chemical Co., Ltd.), Clay minerals such as talc and montmorillonite can also be used.
The average particle size of the layered (tabular) particles is 0.1 to 30 μm, preferably 0.2 to 20 μm, particularly preferably 0.5 to 10 μm, and the aspect ratio is 3 to 2000, preferably 5 ˜1000, particularly preferably 10˜500.

<Thermoplastic fine particles>
The ink receiving layer contains the through-hole particles and / or charged organic fine particles, and when these fine particles have insufficient thermoplasticity, it is preferable to further contain other thermoplastic fine particles. The thermoplastic fine particles function as a binder.
Examples of thermoplastic fine particles include water-dispersed resins such as water-dispersed acrylic resins, water-dispersed polyester resins, water-dispersed polystyrene resins, and water-dispersed urethane resins; acrylic resin emulsions, polyvinyl acetate emulsions, and SBR (styrene / butadiene / rubber) emulsions. And the like, an emulsion in which the following “thermoplastic resin” is dispersed in water, or an aqueous liquid such as a copolymer or a mixture thereof, can be appropriately selected and used in combination of two or more. Commercially available water-dispersed resins include, for example, Toyobo's Byronal MD-1200, MD-1220, MD-1930, Kyoyo Chemical Plus Coat Z-446, Z-465, RZ-96, manufactured by Dainippon Ink & Chemicals, Inc. ES-611, ES-670, Takamatsu Yushi Pesresin A-160P, A-210, A-620, HOSHIRO CHEMICAL HIGH LOSS XE-18, XE-35, XE-48, XE-60, XE-62, Japan Pure drug Jurimer AT-210, AT-510, AT-515, AT-613, ET-410, ET-530, ET-533, FC-60, FC-80 and the like can be mentioned.

Examples of the “thermoplastic resin” will be described below.
(B) Those having an ester bond Dicarboxylic acid components such as terephthalic acid, isophthalic acid, maleic acid, fumaric acid, phthalic acid, adipic acid, sebacic acid, azelaic acid, apietic acid, succinic acid, trimellitic acid, pyromellitic acid (These dicarboxylic acid components may be substituted with sulfonic acid groups, carboxyl groups, etc.) and ethylene glycol, diethylene glycol, propylene glycol, bisphenol A, diether derivatives of bisphenol A (for example, ethylene oxide 2 addition of bisphenol A) Products, bisphenol A propylene oxide 2 adducts, etc.), bisphenol S, 2-ethylcyclohexyldimethanol, neopentyl glycol, cyclohexyldimethanol, glycerin and other alcohol components (these alcohols) The component may be substituted with a hydroxyl group or the like.) Polyester resin obtained by condensation with poly (methacrylate), polymethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polybutyl acrylate or the like, or polymethacrylic acid Examples include ester resins, polycarbonate resins, polyvinyl acetate resins, styrene acrylate resins, styrene-methacrylic acid ester copolymer resins, and vinyl toluene acrylate resins.

  Specific examples include those described in JP-A-59-101395, JP-A-63-7971, JP-A-63-7972, JP-A-63-7793, and JP-A-60-294862. . Commercially available polyester resins include Pylon 290, Pylon 200, Pylon 280, Pylon 300, Pylon 103, Pylon GK-140, Pylon GK-130, Kao's Tufton NE-382 and Tufton U-5 manufactured by Toyobo. , ATR-2009, ATR-2010, Unitika Eritel UE3500, UE3210, XA-8153, Nippon Synthetic Chemical Polyester TP-220, R-188, etc. , Made by Mitsubishi Rayon, dialal SE-5437, SE-5102, SE-5377, SE-5649, SE-5649, SE-5466, SE-5482, HR-169, 124, HR-1127, HR-116, HR-113, HR -148, HR-131, HR-470, HR- 34, HR-606, HR-607, LR-1065, 574, 143, 396, 637, 162, 469, 216, BR-50, BR-52, BR-60, BR-64, BR-73, BR- 75, BR-77, BR-79, BR-80, BR-83, BR-85, BR-87, BR-88, BR-90, BR-93, BR-95, BR-100, BR-101, BR-102, BR-105, BR-106, BR-107, BR-108, BR-112, BR-113, BR-115, BR-116, BR-117, Swreck P, SE-0020 manufactured by Sekisui Chemical Co., Ltd. , SE-0040, SE-0070, SE-0100, SE-1010, SE-1035, Sanyo Chemical Industries Himer ST95, ST120, Mitsui Chemicals FM601, etc. Door can be.

(B) Polyurethane resin (c) Polyamide resin, urea resin, etc. (d) Polysulfone resin (e) Polyvinyl chloride resin, polyvinylidene chloride resin, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl propionate copolymer Commercially available products such as polyol resins such as coalescent resins (f) polyvinyl butyral, cellulose resins such as polyol resins, ethyl cellulose resins, cellulose acetate resins, etc. include those manufactured by Denki Kagaku Kogyo and Sekisui Chemical. The polyvinyl butyral used in the present invention preferably has a polyvinyl butyral content of 70% by mass or more and an average polymerization degree of 500 or more, more preferably an average polymerization degree of 1000 or more. Examples of commercially available products include Denka Butyral 3000-1, 4000-2, 5000A, 6000C manufactured by Denki Kagaku Kogyo Co., Ltd., Sreck BL-1, BL-2, BL-3, BL-S, BX-L, BM- manufactured by Sekisui Chemical. 1, BM-2, BM-5, BM-S, BH-3, BX-1, BX-7 and the like.

(G) Polycaprolactone resin, styrene-maleic anhydride resin, polyacrylonitrile resin, polyether resin, epoxy resin, phenol resin, etc. (h) Polyolefin resin such as polyethylene resin, polypropylene resin, olefin such as ethylene and propylene, and others Copolymers with other vinyl monomers can also be used. Furthermore, as a thermoplastic resin, Japanese Patent Publication Nos. 5-127413, 8-194394, 8-334915, 8-334916, 9-171265, 10-221877 Those satisfying the physical properties disclosed in the above are preferably used.

  The content of the thermoplastic fine particles is preferably 30 to 100% by mass with respect to the total solid content mass of the ink receiving layer including those when the through-hole type fine particles or the charged organic fine particles are thermoplastic, 50-100 mass% is more preferable, and 70-100 mass% is further more preferable.

<Binder resin with low glass transition temperature>
In the present invention, when the brittleness of the porous layer film is insufficient and cracking or the like is likely to occur, it is preferable to add a binder resin having a low glass transition temperature (Tg). Tg is preferably 25 ° C. or lower, more preferably 10 ° C. or lower, and particularly preferably 0 ° C. or lower. The low Tg binder resin can be used as a polymer dispersion. Moreover, even if it is 25 degreeC or more, what is necessary is just to become substantially 25 degreeC or less by using together with an oil-like plasticizer. When a plasticizer is used, the polymer dispersion may be mixed with the plasticizer emulsion and stirred. Examples of the polymer dispersion include polymer dispersions such as vinyl acetate, ethylene vinyl acetate, acrylic, vinylidene chloride, vinyl chloride, butadiene, styrene, and polyester. Examples of the polymer include ethyl acrylate polymer, propyl acrylate polymer, 2-ethoxyethyl acrylate polymer, n-butyl acrylate polymer, propyl acrylate-styrene copolymer, and ethyl acrylate-acrylic acid copolymer. Can be mentioned.
Such low Tg binder dispersions are described in detail in paragraphs 0010 to 0016 of JP-A-4-321045.
By adding a low Tg binder resin, the adhesion between the fine particles is strengthened, the film strength and brittleness are improved, and the curl characteristics are also improved.

<Other additives>
A water-soluble binder, a mordant, fine particles, a gelling agent, a crosslinking agent, and the like that are added to the ink receiving layer of a known inkjet recording medium can be appropriately added to the porous layer and / or the adjacent layer.

(Water-soluble binder)
Examples of the water-soluble binder include a polyvinyl alcohol resin that is a resin having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl. Alcohol, polyvinyl acetal, etc.], cellulose resins (methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.), Chitins, chitosans, starch, resins having an ether bond [polyethylene oxide (PEO), Polypropylene oxide (PPO), polyethylene glycol (PEG), poly ether (PVE)], and resins having carbamoyl groups [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like. Polyvinyl alcohol is preferably used.

(Gelling agent)
The coating solution containing the organic fine particles and the water-soluble polymer of the present invention is coated on a support, and the water-soluble polymer is gelled simultaneously with the coating or before the coated layer shows a reduced drying rate. By applying a solution containing a gelling agent that can be made into a gel, and drying after gelling, the ink receiving layer that is easily cracked at the time of drying does not crack, and a porous ink receiving layer with excellent ink absorbability Can be formed.
As the gelling agent, a boron compound is preferably used when the water-soluble binder is polyvinyl alcohol. Examples of the boron compound include borax, boric acid, borates (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , two Borate (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), can be mentioned five borate _{(e.g., KB 5 O 8 · 4H 2} O, Ca 2 B 6 O 11 · 7H 2 O, CsB 5 O 5) or the like. Among them, Borax, boric acid and borates are preferable, and boric acid is particularly preferable in that a gelation reaction can be promptly caused.

(Crosslinking agent)
As the crosslinking agent for the water-soluble binder, the following compounds other than the boron compound may be used.
For example, aldehyde compounds such as formaldehyde, glyoxal, succinaldehyde, glutaraldehyde, dialdehyde starch, dialdehyde derivatives of plant gum; diacetyl, 1,2-cyclopentanedione, 3-hexene-2,5-dione, etc. Ketone compounds; active halogen compounds such as bis (2-chloroethyl) urea, bis (2-chloroethyl) sulfone, 2,4-dichloro-6-hydroxy-s-triazine sodium salt; divinylsulfone, 1,3-bis (Vinylsulfonyl) -2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide), divinyl ketone, 1,3-bis (acryloyl) urea, 1,3,5-triacryloyl-hexahydro-s- Active vinyl compounds such as triazine; dimethylol urea; N-methylol compounds such as methylol dimethyl hydantoin; melamine compounds such as trimethylol melamine, alkylated methylol melamine, melamine, benzoguanamine, melamine resin; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, diglycerin Epoxy compounds such as polyglycidyl ether, spiroglycol diglycidyl ether, and polyglycidyl ether of phenol resin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate and xylylene diisocyanate; aziridine compounds described in U.S. Pat. Nos. 3,017,280 and 2,983611; and U.S. Pat. No. 3,100,704 Carbodiimide compounds; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxydioxane and the like Dioxane compounds; metal-containing compounds such as titanium lactate, aluminum sulfate, chromium alum, potash alum, zirconyl acetate and chromium acetate; polyamine compounds such as tetraethylenepentamine; hydrazide compounds such as adipic acid dihydrazide; 2 oxazoline groups Including more than Low molecule or polymer having: anhydride of polyvalent acid, acid described in US Pat. No. 2,725,294, US Pat. No. 2,725,295, US Pat. No. 2,726,162, US Pat. No. 3,834,902, etc. Examples include chloride and bissulfonate compounds; active ester compounds described in US Pat. No. 3,542,558, US Pat. No. 3,251972, and the like.
The said crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type.

(mordant)
A mordant is used to fix the anionic dye to the porous layer. The mordant described below can also be used for forming a porous layer as the above-mentioned “fine particles having a positive charge on the surface” or “water-soluble polymer having a positive charge”.
As the mordant, a cationic polymer (cationic mordant) or an inorganic mordant is preferably used.
As the cationic mordant, a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic group is preferably used, but a cationic non-polymer mordant can also be used. . These mordants are preferably compounds having a weight average molecular weight of 500 to 100,000 from the viewpoint of improving ink absorbability of the porous layer.
Examples of the polymer mordant include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (mordant monomer), and the mordant monomer and other monomers (hereinafter, What is obtained as a copolymer or condensation polymer with "non-mordant monomer") is preferred. These polymer mordants can be used in any form of water-soluble polymer or water-dispersible latex particles.

  Examples of the monomer (mordanting monomer) include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N , N-dimethyl-N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-N -P-vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-die Ru-N-benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-N -P-vinylbenzylammonium chloride;

  Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate;

  N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted with their anions.

  Specifically, for example, monomethyl diallyl ammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, triethyl- 2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl-2- (Methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylamino) ethyl Ammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) propylammonium chloride Triethyl-3- (acryloylamino) propylammonium chloride;

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate.
In addition, examples of copolymerizable monomers include N-vinylimidazole and N-vinyl-2-methylimidazole.

In addition, allylamine, diallylamine, its derivatives, salts and the like can be used. Examples of such compounds include allylamine, allylamine hydrochloride, allylamine acetate, allylamine sulfate, diallylamine, diallylamine hydrochloride, diallylamine acetate, diallylamine sulfate, diallylmethylamine and salts thereof (for example, Hydrochloride, acetate, sulfate, etc.), diallylethylamine and salts thereof (for example, hydrochloride, acetate, sulfate, etc.), diallyldimethylammonium salt (chloride, acetic acid as counter anions of the salt) Ion sulfate ions, etc.). In addition, since these allylamines and diallylamine derivatives are inferior in polymerizability in the form of amines, they are generally polymerized in the form of salts and desalted as required.
In addition, a unit such as N-vinylacetamide, N-vinylformamide or the like, which is converted into a vinylamine unit by hydrolysis after polymerization, and a salt thereof can also be used.

The non-mordant monomer does not contain a basic or cationic moiety such as a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base, and does not show an interaction with a dye in an inkjet ink. Or the monomer which interaction is substantially small is said.
Examples of the non-mordant monomer include (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; Aralkyl esters such as (meth) benzyl acrylate; aromatic vinyls such as styrene, vinyl toluene and α-methylstyrene; vinyl esters such as vinyl acetate and vinyl propionate; allyl esters such as allyl acetate; vinylidene chloride; And halogen-containing monomers such as vinyl chloride; vinyl cyanide such as (meth) acrylonitrile; and olefins such as ethylene and propylene.

The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, such as methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Of these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable.
The non-mordant monomers can also be used singly or in combination of two or more.

Further, as the polymer mordant, polydiallyldimethylammonium chloride, a copolymer of diallyldimethylammonium chloride and another monomer (mordant monomer, non-mordant monomer), a copolymer of diallyldimethylammonium chloride and SO ₂ , polydiallyl Cyclic amine resins represented by methylamine hydrochloride, polydiallyl hydrochloride and the like (including copolymers); polydiethylmethacryloyloxyethylamine, polytrimethylmethacryloyloxyethylammonium chloride, polydimethylbenzylmethacryloyloxyethylammonium chloride, Secondary amino, tertiary amino or quaternary ammonium salt-substituted alkyls such as polydimethylhydroxyethylacryloyloxyethylammonium chloride (Meth) acrylate polymers and copolymers with other monomers; polyamine resins such as polyethyleneimine and derivatives thereof, polyallylamine and derivatives thereof, polyvinylamine and derivatives thereof; polyamide-polyamine resin, polyamide epichloro Polyamide resins typified by hydrin resins, etc .; Polysaccharides typified by cationized starch, chitosan and chitosan derivatives; dicyandiamide formalin polycondensates, dicyandiamide diethylenetriamine polycondensates and other dicyandiamide derivatives; polyamidines and polyamidine derivatives Dialkylamine epichlorohydrin addition polymer such as dimethylamine epichlorohydrin addition polymer and derivatives thereof; styrene heavy having a quaternary ammonium salt-substituted alkyl group Body and copolymers of other monomers may be mentioned as being also preferred.

  Specific examples of the polymer mordant include JP-A Nos. 48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, and 60. -23851, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122294 No. 60-235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, JP 4282305, JP 4450224, JP-A-1-16123. No. 10-81064, No. 10-157277, No. 10-217601, JP-A No. 2001-138621, No. 2000-212235, No. 2001-138627, JP-A No. 8-174992, JP-B No. 5-174992 35162, 5-35163, 5-35164, 5-88846, Japanese Patent Nos. 2648847, 2616677 and the like.

An inorganic mordant can also be used as the mordant in the present invention, and examples thereof include polyvalent water-soluble metal salts and hydrophobic metal salt compounds.
Specific examples of the inorganic mordant include, for example, magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, lanthanum, Examples thereof include salts or complexes of metals selected from cerium, praseodymium, neodymium, samarium, europium, gadolinium, dysproprosium, erbium, ytterbium, hafnium, tungsten, and bismuth.

  Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride Dicopper, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate Ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum alum, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, basic aluminum sulfate, Basic aluminum nitrate, basic aluminum formate , Basic aluminum acetate, basic aluminum glycinate, ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc phenolsulfonate, zinc bromide, zinc chloride , Zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, titanium lactate, zirconium acetylacetonate, zirconyl acetate, zirconyl sulfate, ammonium zirconium carbonate, zirconyl stearate, zirconyl octylate, Zirconyl nitrate, zirconium oxychloride, hydroxyzirconium chloride, zirconyl lactate, zirconyl succinate, zirconyl oxalate, ammonium zirconium acetate, potassium zirconium carbonate, basic zirconium glycinate, chromium acetate, chromium sulfate, magnesium sulfate , Magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdoline Acid n hydrate, gallium nitrate, germanium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride, lanthanum acetate, lanthanum benzoate, cerium chloride, cerium sulfate, cerium octylate, Examples thereof include praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

  As the inorganic mordant, an aluminum-containing compound, a titanium-containing compound, a zirconium-containing compound, and a metal compound (salt or complex) of Group IIIB of the Periodic Table of Elements are preferable.

  When these mordants are used as a fixing agent for anionic dyes, the liquid containing the mordant is dipped or curtain-coated after the coating liquid for forming the porous layer is applied and dried, or in the middle of drying (rawly dried). It can also be applied separately by the extrusion method or the like.

<Other ingredients>
The recording medium of the present invention may further contain various known additives such as acids, ultraviolet absorbers, antioxidants, fluorescent whitening agents, anti-bleeding agents, preservatives, viscosity stabilizers, and antifoaming agents as necessary. , Surfactants, antistatic agents, matting agents, anti-curling agents, water-proofing agents, and the like.

(acid)
Specific examples of acids include formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, isophthalic acid , Glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, salicylic acid, salicylic acid metal salts (salts such as Zn, Al, Ca, Mg), methanesulfonic acid, itaconic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethanesulfone Acid, styrenesulfonic acid, trifluoroacetic acid, barbituric acid, acrylic acid, methacrylic acid, cinnamic acid, 4-hydroxybenzoic acid, aminobenzoic acid, naphthalenedisulfonic acid, hydroxybenzenesulfonic acid, toluenesulfinic acid, benzenesulfinic acid, Sulfanilic acid, sulfamic acid, α-le Examples include ricinic acid, β-resorcinic acid, γ-resorcinic acid, gallic acid, phloroglicin, sulfosalicylic acid, ascorbic acid, erythorbic acid, bisphenolic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, boric acid, boronic acid, etc. It is done. What is necessary is just to determine the addition amount of these acids so that the surface PH of a porous layer may be set to 3-8.
The acid may be a metal salt (eg, sodium, potassium, calcium, cesium, zinc, copper, iron, aluminum, zirconium, lanthanum, yttrium, magnesium, strontium, cerium, etc.) or an amine salt (eg, ammonia, triethylamine, tri Butylamine, piperazine, 2-methylpiperazine, polyallylamine, etc.). Examples of metal salts include polyaluminum chloride, zirconium oxychloride, zirconyl acetate and the like.

(UV absorber, antioxidant, anti-bleeding agent)
Alkylated phenol compounds (including hindered phenol compounds), alkylthiomethylphenol compounds, hydroquinone compounds, alkylated hydroquinone compounds, tocopherol compounds, aliphatic / aromatic and / or heterocyclic compounds having a thioether bond, bisphenol compounds, O- , N- and S-benzyl compounds, hydroxybenzyl compounds, triazine compounds, phosphonate compounds, acylaminophenol compounds, ester compounds, amide compounds, ascorbic acid, amine antioxidants, 2- (2-hydroxyphenyl) benzotriazole compounds 2-hydroxybenzophenone compound, acrylate, water-soluble or hydrophobic metal salt, organometallic compound, metal complex, hindered amine compound (including TEMPO compound), 2- (2- (Droxyphenyl) 1,3,5, -triazine compound, metal deactivator, phosphite compound, phosphonite compound, hydroxyamine compound, nitrone compound, peroxide scavenger, polyamide stabilizer, polyether compound, basic auxiliary Stabilizer, nucleating agent, benzofuranone compound, indolinone compound, phosphine compound, polyamine compound, thiourea compound, urea compound, hydrazide compound, amidine compound, sugar compound, hydroxybenzoic acid compound, dihydroxybenzoic acid compound, trihydroxybenzoic acid compound, etc. Is mentioned.

  Among these, alkylated phenol compounds, aliphatic / aromatic and / or heterocyclic compounds having a thioether bond, bisphenol compounds, ascorbic acid, amine-based antioxidants, water-soluble or hydrophobic metal salts, organometallic compounds, Metal complexes, hindered amine compounds, hydroxyamine compounds, polyamine compounds, thiourea compounds, hydrazide compounds, hydroxybenzoic acid compounds, dihydroxybenzoic acid compounds, trihydroxybenzoic acid compounds, and the like are preferred.

  Specific examples of the compound include Japanese Patent Application No. 2002-13005, Japanese Patent Application Laid-Open No. 10-182621, Japanese Patent Application Laid-Open No. 2001-260519, Japanese Patent Application No. 4-34953, Japanese Patent Application No. Hei 4-345513, Japanese Patent Application Laid-Open No. 11-170686, No. 4-34512, EP 1138509, JP-A-60-67190, JP-A-7-276808, JP-A-2001-94829, JP-A-47-10537, JP-A-58-111942, and JP-A-58-212844. 59-19945, 59-46646, 59-109055, 63-53544, JP 36-10466, 42-26187, 48-30492, 48-31255, 48-41572, 48-54965, 50-10726, U.S. Pat.No. 2,719,086, 3 No. 707,375, the 3,754,919 Patent, the 4,220,711 Patent,

  Japanese Patent Publication Nos. 45-4699, 54-5324, European Published Patent Nos. 223739, 309401, 309402, 3105301, 310552, 459416, German Published Patent No. 3435443, Kaisho 54-48535, 60-107384, 60-107383, 60-125470, 60-125471, 60-125472, 60-287485, 60-287486, 60-287487, 60-287488, 61-160287, 61-18854, 61-2111079, 62-146678, 62-146680, 62-146679, 62- No. 282885, No. 62-262047, No. 63-051174, Nos. 63-89877, 63-88380 same issue, same 63-88381 JP, same 63-113536 issue,

  63-163351, 63-203372, 63-224989, 63-251282, 63-267594, 63-182484, JP-A-1-239282, JP-A-2-262654, 2-71262, 3-121449, 4-291865, 4-291684, 5-611166, 5-119449, 5-188687, 5-188686, 5 No. 110490, No. 5-170361, No. 48-43295, No. 48-33212, U.S. Pat. Nos. 4,814,262, and No. 4,980,275.

The other components may be used alone or in combination of two or more. These other components may be added after being water-solubilized, dispersed, polymer-dispersed, emulsified or oil-dropped, or may be encapsulated in microcapsules. The recording medium of the present invention, the addition amount of other components, preferably 0.01 to 10 g / m ^2.

In the present invention, the porous layer coating solution preferably contains a surfactant. As the surfactant, any of cationic, anionic, nonionic, amphoteric, fluorine and silicon surfactants can be used.
Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (for example, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyalkylene ether) Ethylene nonylphenyl ether), oxyethylene / oxypropylene block copolymer, sorbitan fatty acid esters (for example, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (for example, polyoxyethylene) Sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitant Oleate, etc.), polyoxyethylene sorbitol fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (eg, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polyoxymonostearate) Ethylene glycerin, monooleic acid polyoxyethylene glycerin, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, acetylene glycols (eg, 2, 4, 7) , 9-tetramethyl-5-decyne-4,7-diol, and ethylene oxide adducts and propylene oxide adducts of the diols), and the like. Sharp emission alkyl ethers are preferable. The nonionic surfactant can be used in the first coating solution and the second coating solution. Moreover, the said nonionic surfactant may be used independently and may use 2 or more types together.

  Examples of the amphoteric surfactant include amino acid type, carboxyammonium betaine type, sulfoammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, etc., for example, US Pat. No. 3,843,368, JP, JP-A-59-49535, JP-A-63-236546, JP-A-5-303205, JP-A-8-262742, JP-A-10-282619, JP-A-2514194, JP-A-2759597, JP-A-2000-351269, etc. Can be used preferably. Among the amphoteric surfactants, the amino acid type, carboxyammonium betaine type, and sulfoneammonium betaine type are preferable. The amphoteric surfactant may be used alone or in combination of two or more.

Examples of the anionic surfactant include fatty acid salts (for example, sodium stearate, potassium oleate), alkyl sulfate esters (for example, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (for example, sodium dodecylbenzene sulfonate). Alkyl sulfosuccinate (for example, sodium dioctyl sulfosuccinate), alkyl diphenyl ether disulfonate, alkyl phosphate, and the like.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, pyridinium salts, imidazolium salts, and the like.

Examples of the fluorosurfactant include compounds derived from an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, or oligomerization.
Examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl group-containing oligomers, and perfluoroalkyl phosphate esters.

  As the silicon-based surfactant, silicon oil modified with an organic group is preferable, and a structure in which a side chain of a siloxane structure is modified with an organic group, a structure in which both ends are modified, and a structure in which one end is modified can be taken. Examples of the organic group modification include amino modification, polyether modification, epoxy modification, carboxyl modification, carbinol modification, alkyl modification, aralkyl modification, phenol modification, and fluorine modification.

  In the present invention, the content of the surfactant is preferably 0.001 to 2.0%, more preferably 0.01 to 1.0% with respect to the coating liquid for the porous layer. Moreover, when performing application | coating using 2 or more liquids as a coating liquid for porous layers, it is preferable to add surfactant to each coating liquid.

The porous layer may contain a high-boiling organic solvent for preventing curling and / or adjusting the glass transition temperature. The high-boiling organic solvent is an organic compound having a boiling point of 150 ° C. or higher at normal pressure, and is a water-soluble or hydrophobic compound. These may be liquid or solid at room temperature, and may be low molecules or polymers.
Specifically, aromatic carboxylic acid esters (for example, dibutyl phthalate, diphenyl phthalate, phenyl benzoate, etc.), aliphatic carboxylic acid esters (for example, dioctyl adipate, dibutyl sebacate, methyl stearate, dibutyl maleate) , Dibutyl fumarate, triethyl acetyl citrate, etc.), phosphate esters (eg, trioctyl phosphate, tricresyl phosphate, etc.), epoxies (eg, epoxidized soybean oil, epoxidized fatty acid methyl, etc.), alcohols (eg, stearyl) Alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerol, diethylene glycol monobutyl ether (DEGMBE), triethylene glycol monobutyl ether, glycerol Methyl ether, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, triethanolamine, polyethylene glycol, etc. ), Vegetable oils (eg, soybean oil, sunflower oil, etc.) and higher aliphatic carboxylic acids (eg, linoleic acid, oleic acid, etc.).

≪Support body≫
As the support in the present invention, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to increase the ink absorption rate of the porous layer, it is preferable to use paper. Further, a porous layer can be provided on the label surface side using a read-only optical disk such as a CD-ROM or DVD-ROM, a write-once optical disk such as a CD-R or DVD-R, or a rewritable optical disk as a support.

The material that can be used for the transparent support is preferably a material that is transparent and can withstand radiant heat when used in an OHP or a backlight display. Examples of the material include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide and the like. Of these, polyesters are preferable, and polyethylene terephthalate is particularly preferable.
Although there is no restriction | limiting in particular as thickness of the said transparent support body, 50-200 micrometers is preferable at the point which is easy to handle.

  As the highly glossy opaque support, one having a glossiness of 40% or more on the surface on which the porous layer is provided is preferable. The glossiness is a value determined according to the method described in JIS P-8142 (75-degree specular gloss test method for paper and paperboard). Specifically, the following supports are mentioned.

For example, high gloss paper support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, etc .; polyesters such as polyethylene terephthalate (PET), nitrocellulose, cellulose acetate , Cellulose esters such as cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by adding a white pigment or the like (surface calendering may be applied). Glossy film; or a support in which a polyolefin coating layer containing or not containing a white pigment is provided on the surface of a highly glossy film containing the various paper supports, the transparent support or the white pigment. Etc.
A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) can also be suitably exemplified. Furthermore, resin-coated paper used for silver salt photographic printing paper is also suitable.

  Although there is no restriction | limiting in particular also about the thickness of the said opaque support body, 50-300 micrometers is preferable at the point of handleability.

  The surface of the support may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, etc. in order to improve wettability and adhesion.

Next, the base paper used for the resin-coated paper will be described in detail.
As the base paper, wood pulp is used as a main raw material, and paper is made using synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester in addition to wood pulp as necessary. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, LDP with a lot of short fibers. preferable.
However, the ratio of LBSP and / or LDP is preferably 10% by mass or more and 70% by mass or less.

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

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

  The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is a 24 mesh residual mass% and a 42 mesh residual as defined in JIS P-8207. 30 to 70% of the sum with the mass% of 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 30 to 250 g, and particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / m ² (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 size 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 a hot water extraction method defined in JIS P-8113.

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

  In particular, the polyethylene layer on the side forming the porous layer is added with rutile or anatase type titanium oxide, fluorescent whitening agent, ultramarine, and polyethylene, as is widely done in photographic paper. Those having improved whiteness and hue are preferred. Here, as a titanium oxide content, about 3-20 mass% is preferable with respect to polyethylene, and 4-13 mass% is more preferable. Although the thickness of a polyethylene layer does not have limitation in particular, 10-50 micrometers is suitable for both front and back layers. Further, an undercoat layer can be provided on the polyethylene layer in order to provide adhesion with the porous layer. As the undercoat layer, aqueous polyester, gelatin and PVA are preferable. Moreover, as thickness of this undercoat layer, 0.01-5 micrometers is preferable.

Polyethylene-coated paper can be used as glossy paper, or matte or silky surface that can be obtained with ordinary photographic printing paper by applying a so-called molding process when melt-extruding polyethylene onto the base paper surface for coating. Can also be used.
The polyethylene layer is usually laminated by a melt extrusion method of polyethylene, but can also be provided by applying an aqueous dispersion of polyethylene particles and heating and drying. Resin-coated paper can also be produced by applying a polymer dispersion other than polyethylene.

A back coat layer can be provided on the support, and examples of components that can be added to the back coat layer include a white pigment, an aqueous binder, and other components.
Examples of white pigments contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. , Diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigment, styrene And organic pigments such as polyethylene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

Examples of the aqueous binder used in the back coat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxy Examples thereof include water-soluble polymers such as methyl cellulose, hydroxyethyl cellulose, and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion.
Examples of other components contained in the backcoat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

  The use of the recording medium of the present invention is not particularly limited, but is preferably for inkjet. The ink to be used is not particularly limited, and water-soluble dye-based, pigment-based, solvent-based inks and the like described later can be used. In the case of an ink containing a polymerizable monomer, the effects of the present invention can be further exhibited.

≪Recording medium manufacturing method≫
The recording medium of the present invention supports an ink receiving layer (porous layer) by applying a coating liquid for forming an ink receiving layer (porous layer) containing organic fine particles and a polymerizable initiator to a support. It is made by forming on the body.
The coating solution for the ink receiving layer is prepared by dispersing and dissolving each component forming the ink receiving layer in a solvent, preferably an aqueous solvent.
As the solvent, water, an organic solvent, or a mixed solvent thereof can be used. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone, and tetrahydrofuran.

  When the organic fine particles include the charged organic fine particles and at least one of the charged organic fine particles is weakly charged, the pH of the coating solution is adjusted in advance to balance the coating property and the cross-linking aggregation property. A coating layer formed by applying a coating on a support (first method), or setting the pH of the coating solution to a pH most suitable for coating properties, and simultaneously or by coating the coating solution on a support Before drying, it is preferable to adjust the pH so as to obtain a pH suitable for crosslinking and aggregation by adding a pH adjusting agent to the coating layer (second method).

In the first method, the pH of the coating solution is controlled such that fine particles are stably dispersed in the coating solution, the viscosity of the coating solution is suitable for coating, and aggregation of fine particles after coating (crosslinking aggregation). In view of the good formation of the porous layer by the above) (If too much emphasis is placed on dispersion stability and applicability, suitable cross-linking aggregation may not occur. If too much consideration is taken into account, dispersion stability and applicability may decrease), and it is preferable to determine an optimum pH range.
As the pH adjuster of the coating solution, alkali metal compounds such as NaOH and KOH, ammonia water, amine compounds and the like are used to raise the pH, and hydrochloric acid, sulfuric acid, phosphoric acid and the like are used to lower the pH. Inorganic acids and organic acids such as acetic acid can be used.

  In addition, as a pH adjuster of the coating solution, for example, a volatile pH adjuster is used, and the pH of the coating solution is set to a pH suitable for coating, and the pH regulator is volatilized from the coating layer after coating. A method is also preferred in which the pH of the coating layer is adjusted to a pH suitable for cross-linking aggregation. A volatile pH adjuster means having a vapor pressure to the extent that it volatilizes in the drying step when forming the porous layer. Examples of the volatile pH adjuster include aqueous ammonia, aqueous amine solution, hydrochloric acid, acetic acid and the like.

For example, the combination of weak cationic microparticles / strong anionic fine particles ^- in (Example-NH. ₂ group-containing microparticles / -SO ₃ combination groups containing fine particles), the use of aqueous ammonia as a pH adjusting agent of the coating solution, the coating After application of the liquid, ammonia is volatilized from the coating layer, the pH of the coating layer is lowered, and cross-linking aggregation is promoted. At this time, the coating layer may be heated and dried to promote volatilization. A method of increasing the pH by decarboxylation by heating or the like is also effective. For example, weakly alkaline sodium hydrogen carbonate decomposes at 65 ° C. or higher to become strongly alkaline sodium carbonate.

Examples of the pH adjusting agent used in the second method include a liquid pH adjusting agent and a method using a gaseous pH adjusting agent.
As a method of adjusting the pH of the coating layer using a liquid pH adjuster, a solution containing the pH adjuster is applied on the coating layer by the coating solution for forming a porous layer (multilayer coating), or It is performed by a method such as spraying a mist of a liquid containing a pH adjusting agent on the coating layer. The application or spraying is performed simultaneously with the formation of the application layer or before the application layer formed by application is dried. As the liquid containing the pH adjusting agent, the pH adjusting agent used in the above-mentioned coating solution is used in the same manner.
The method for adjusting the pH of the coating layer using a gaseous pH adjusting agent is performed by applying a gaseous pH adjusting agent on the coating layer. As the pH regulator, ammonia gas, hydrochloric acid gas, carbon dioxide gas or the like is used.

  In addition, the coating solution in the second method has a pH value in order to obtain a positive and negative charge amount ratio such that fine particles and the like are stably dispersed in the coating solution, and the coating solution has a viscosity suitable for coating. On the other hand, by applying a pH regulator in the coating layer after coating and readjusting the positive and negative charge amount ratio, it causes cross-linking aggregation that forms the desired porous structure in a short time It is preferable to adjust the pH of the coating layer so as to change to an effective pH.

In the second method, when a combination of charged fine particles, at least one of which is weakly charged, the pH of the coating layer is specifically adjusted as follows.
1) In the case of a combination of weak anionic fine particles / strong cationic fine particles (eg, a combination of -COOH group-containing fine particles / quaternary ammonium base-containing fine particles), it is carried out by applying an alkaline pH adjusting agent.
2) The combination of weakly cationic microparticles / strong anionic fine particles (eg-NH. ₂ group-containing microparticles / -SO ₃ ^- the combination of group-containing fine particles) is carried out by applying an acidic pH adjusting agent.
3) In the case of a combination of weak anionic fine particles / weak cationic fine particles (eg, a combination of -COOH group-containing fine particles / -NH ₂ group-containing fine particles), it is carried out with an acidic or alkaline pH adjusting agent.

The coating solution can be applied by a known coating method such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or a bar coater.
In addition, when a pH adjusting agent is applied in multiple layers on the coating layer, an extrusion die coater is preferably used. In addition, a method in which the gelling agent or / and pH adjusting agent of the coating solution is floated by dip coating or spraying before the coating layer exhibits a reduced rate of drying is preferably used.

[Recording method]
The recording method of the present invention is characterized by recording on the recording medium of the present invention using an ink containing a polymerizable monomer (hereinafter also referred to as “monomer ink”).
The monomer ink is an ink that contains components other than the polymerization initiator and is polymerized and cured by heating or irradiating light (such as ultraviolet rays) after printing.
When recording using the ink containing a polymerizable monomer on the recording medium of the present invention, it is preferable to heat (apply heat) the recording medium after printing or to heat after light irradiation (heat application after light irradiation). . In particular, the operation is preferably after the monomer ink has penetrated into the ink receiving layer.
In the case where the recording initiator contains the polymerization initiator and recording is performed using a monomer ink, the monomer ink preferably does not contain a polymerization initiator. By recording on the recording medium using the monomer ink that does not contain the polymerization initiator, the monomer ink is polymerized and solidified with less clogging even when the ink is heated by an inkjet head, and high-speed printing by a line head is possible. Tend to be.

Furthermore, it is preferable to perform light irradiation and smoothing on the recording medium obtained immediately after printing on the recording medium using the monomer ink. Conventionally, smoothing immediately after printing on a recording medium: heating and pressing (for example, a method in which a smooth film is layered on the printing surface and passed through a heat roller) does not eliminate haze in the film, and the film is sufficiently dried. The sharpness, color density and glossiness of the image were not always sufficient as compared with the case where the smoothing process was performed. In the present invention, if printing is performed on the recording medium of the present invention using a monomer ink as the ink, the smoothing process is performed immediately after printing, and the pores of the ink receiving layer are clogged with the cured ink even after a long period of time. As it is, no light scattering occurs in the ink receiving layer, and glossiness, color density, saturation, image sharpness, etc. do not decrease.
The image obtained by the smoothing process tends to be excellent in glossiness.
Furthermore, the monomer ink that has penetrated into the pores undergoes a polymerization reaction simultaneously with the smoothing treatment, and the monomer ink is fixed to the pores together with the pigment. That is, the pores are filled with the polymer, and the ozone resistance tends to be greatly improved.
Examples of the smoothing include a method of pressurizing the stamp screen (pressure smoothing), a method of heating (heating smoothing), and a method of heating and pressurizing (heating and pressure smoothing). Pressure smoothing is preferable in that it also serves as heating for initiating the polymerization reaction. In the case of smoothing by heating, the recording medium is appropriately cooled as necessary after heating.

  Examples of the pressure means used for the pressure smoothing include a method in which a recording medium after printing is passed through a pressure contact portion (nip portion) of a pressure roll formed of a pair of rolls. As the pressure roll, a surface of a metal roll made of stainless steel or the like that is mirror-finished by hard chrome plating or the like is used. The pressurizing condition is about 16 to 100 kg / cm.

  Moreover, as a heating means used for heating smoothing, there is a method of heating from the upper part of the printing screen of the recording medium after printing with radiant heat such as an infrared lamp or a planar heater. The heating temperature on the surface of the recording medium is appropriately selected depending on the Tg of the porous layer, but is generally about 80 to 160 ° C.

  Furthermore, as heating / pressurizing means used for heating / pressurizing smoothing, a method of passing a recording medium after printing through a nip portion of a pair of heating rolls provided with heating means inside at least one roll, or a pressure roll And a method of passing a recording medium after printing through the nip portion of the heating belt, among others, smoothing using a heating roll is preferable.

As the pair of heating rolls, those provided with a release layer such as silicone resin (rubber) or fluororesin (rubber) on the surface of a metal roll such as aluminum or stainless steel are used. Moreover, an elastic body layer can be appropriately provided under the release layer. Moreover, as a heating means provided in a roll, well-known heating means, such as a halogen lamp, an electric heating system, and a dielectric heating system, can be employed.
A method in which light irradiation is performed simultaneously with the heating / pressurizing treatment and the photopolymerization and the thermal polymerization proceed simultaneously is preferable. In this method, for example, a roll, belt, or plate used on the printing surface side when performing heating / pressurizing treatment is made transparent using glass, quartz, etc., and heating and light irradiation are simultaneously performed using a halogen lamp or the like. is there.
The heating temperature on the surface of the recording medium in the heating / pressurization smoothing by the pair of heating rolls is appropriately selected depending on the Tg of the porous layer, but is generally about 80 to 160 ° C. Moreover, pressurization conditions are about 1-30 Kg / cm.

A heating belt used for heating / pressurizing smoothing has a plurality of rolls and a belt stretched between the rolls, and heating means is provided inside one of the rolls. And the pressure roll which forms a nip part is provided facing the roll provided with the said heating means. A heating means may also be provided in the pressure roll. As a heating means provided in the roll, a known heating means such as a halogen lamp, an electric heating method, a dielectric heating method, or the like can be adopted.
As the pair of facing rolls, a roll provided with a release layer such as silicone resin (rubber) or fluororesin (rubber) on the surface of a metal roll such as aluminum or stainless steel is used. In addition, in consideration of heat resistance and mechanical strength, the belt is made of a silicone rubber, on a metal sheet such as nickel, aluminum, stainless steel, or a resin film such as PET, PBT, polyester, polyimide, polyimide amide, What formed the release layer containing the rubber | gum excellent in heat resistance and mold release property, such as a fluorine-type rubber and a silicone- fluorine-type rubber, can be used.

In the case of pressure smoothing using a heating belt and a pressure roll, the heating temperature on the surface of the recording medium is appropriately selected depending on the Tg of the porous layer, but is generally about 80 to 160 ° C. Moreover, pressurization conditions are about 1-30 kg / cm.
Further, when the heating belt is peeled off from the surface of the recording medium after heating, it is preferable to cool the heating belt before peeling before peeling.

FIG. 1 shows an example of a heating roll used for heating / pressurizing smoothing. In FIG. 1, 10 and 20 are rolls, 12 and 22 are metal rolls, and 14 and 24 are release layers. Further, a halogen lamp, for example, is provided as a heating means 16 inside the roll 10. Reference numeral 30 denotes a printed recording medium, and the printing screen is smoothed by passing through the nip portion of a pair of rolls.
FIG. 2 shows another means used for heating / pressurizing smoothing. 40 indicates a heating belt, 42 indicates a belt, 44 indicates a heating roll, 45 indicates a metal roll, 46 indicates a release layer, and 48 indicates a halogen lamp. The heating means 49 and the like, 49 respectively indicate support rolls. Reference numeral 50 denotes a pressure roll that forms a nip portion with the heating roll 44, 52 denotes a metal roll, and 54 denotes a release layer.

Hereinafter, the recording ink will be described in detail.
<Monomer ink>
The monomer ink used in the recording method of the present invention contains a polymerizable monomer, but is not particularly limited. The ink preferably contains a colorant.

(Polymerizable monomer)
As the polymerizable monomer that can be used in the present invention, a monomer that undergoes addition polymerization or ring-opening polymerization by a radical species or a cationic species generated from a photopolymerization initiator by ultraviolet irradiation to generate a polymer is preferably used. Examples of the polymerization mode of addition polymerization include radical, cation, anion, metathesis, and coordination polymerization. Examples of the ring-opening polymerization method include cation, anion, radical, metathesis, and coordination polymerization.
As the polymerization mode of the present invention, radical polymerization is preferably used, but it can be used in combination with a polymerizable monomer that is cured by another polymerization mode. As the polymerizable monomer, a compound that undergoes addition polymerization in particular by radical polymerization can be preferably used.

Examples of the addition polymerizable monomer include compounds having at least one ethylenically unsaturated double bond. As the addition polymerizable monomer, a compound having at least one terminal ethylenically unsaturated bond, preferably two or more, can be preferably used. Such terminal ethylenically unsaturated compounds are widely known in the industrial field. In the present invention, the monomer ink can be used without particular limitation as long as it can be stably ejected from the inkjet nozzle.
Ethylenically unsaturated polymerizable monomers include those having a chemical form of monofunctional polymerizable monomers and polyfunctional polymerizable monomers (ie, bifunctional, trifunctional and 4-6 functional), or mixtures thereof. It is done. Examples of the monofunctional polymerizable monomer include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters thereof, and amides. As the polyfunctional polymerizable monomer, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used.

  Also, addition reaction products, monofunctional or polyfunctional unsaturated carboxylic acid esters or amides having a nucleophilic substituent such as hydroxyl group, amino group, mercapto group and the like with monofunctional or polyfunctional isocyanates and epoxies. A dehydration condensation reaction product with a functional carboxylic acid can also be used. In addition, an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an isocyanate group or an epoxy group, a monofunctional or polyfunctional alcohol, an amine and an addition reaction product of a thiol with a halogen compound, halogen Substitution reaction products of unsaturated carboxylic acid esters or amides having a leaving substituent such as a group or tosyloxy group with monofunctional or polyfunctional alcohols, amines and thiols can also be used.

  As a specific example of the radical polymerizable monomer which is an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, (meth) acrylic acid ester is representative, and at least one kind of trifunctional or higher functional (meth) acrylate is used. , And at least one of monofunctional and / or bifunctional (meth) acrylates is preferably used.

  Specific examples of monofunctional (meth) acrylates include tolyloxyethyl (meth) acrylate, phenyloxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, innobornyl ( Mention may be made of (meth) acrylate and tetrahydrofurfuryl (meth) acrylate.

  Specific examples of the bifunctional (meth) acrylate include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, Propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, Mention may be made of pentaerythritol di (meth) acrylate and dipentaerythritol di (meth) acrylate.

  Specific examples of trifunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane alkylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate , Dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, propionate dipentaerythritol tri (meth) acrylate, tri ((meta ) Acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) acrylate Mention may be made of the rate.

  Specific examples of tetrafunctional (meth) acrylates include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate propionate, ethoxylated penta Mention may be made of erythritol tetra (meth) acrylate.

  Specific examples of the pentafunctional (meth) acrylate include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.

  Specific examples of hexafunctional (meth) acrylate include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, captolactone modified dipentaerythritol hexa (meth) acrylate Can be mentioned.

  Here, the above notation of (meth) acrylate is an abbreviated notation indicating that it can have both a methacrylate structure and an acrylate structure.

  Radical polymerizable monomers that are esters of various unsaturated carboxylic acids and aliphatic alcohol compounds are commercially available, PEG 600 diacrylate (EB11: manufactured by Daicel UCB), KAYARAD DPCA-60 (force prolactone modified dipenta Examples include erythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.) and SR-494 (ethoxylated pentaerythritol tetraacrylate: manufactured by Sartomer).

  In the present invention, the polymerizable monomer preferably contains at least one functional (meth) acrylate. The polymerizable monomer preferably contains (a) at least one trifunctional or higher functional (meth) acrylate, and (b) at least one monofunctional and / or bifunctional (meth) acrylate. Further, (a) the trifunctional or higher functional (meth) acrylate is more preferably a tetrafunctional, pentafunctional or hexafunctional (meth) acrylate.

In addition to (meth) acrylate, itaconic acid ester, crotonic acid ester, isocrotonic acid ester, maleic acid ester and the like can also be used as the polymerizable monomer.
Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.

  Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate.

  Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.

  Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.

  Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, and JP-A-59-5240. Those having an aromatic skeleton as described in JP-A-59-5241 and JP-A-2-226149, those containing an amino group as described in JP-A-1-165613, and the like can also be used.

  Specific examples of amide monomers of unsaturated carboxylic acid and aliphatic polyvalent amine compound include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like.

  Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.

Further, urethane-based addition polymerizable monomers produced by using an addition reaction of inocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, 1 described in JP-B-48-41708. Vinyl urethane containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following formula (5) to a polyisocyanate compound having two or more isocyanate groups in the molecule. Compounds and the like.
Formula (5)
^{_{CH 2 = C (R 1)}} COOCH 2 CH (R 2) OH
(However, R ¹ and R ² represent H or CH _3. )

  In the present invention, a cationic ring-opening polymerizable compound having at least one cyclic ether group such as an epoxy group and / or an oxetane group in the molecule can be used as an ultraviolet curable binder together with an ultraviolet cationic polymerization initiator. .

The general cationic polymerizable monomers preferably used in the present invention will be described below. Examples of the cationic polymerizable monomer include a curable compound containing a ring-opening polymerizable group, and among them, a heterocyclic group-containing curable compound is preferable. Examples of such curable compounds include epoxy derivatives, oxetane derivatives, tetrahydrofuran derivatives, cyclic lactone derivatives, cyclic carbonate derivatives, cyclic imino ethers such as oxazoline derivatives, and vinyl ethers. preferable.
Examples of preferable epoxy derivatives are roughly classified into monofunctional glycidyl ethers, polyfunctional glycidyl ethers, monofunctional alicyclic epoxies, polyfunctional alicyclic epoxies, and the like.

  Specific examples of monofunctional and polyfunctional glycidyl ethers include diglycidyl ethers (for example, ethylene glycol diglycidyl ether, bisphenol A diglycidyl ether), trifunctional or higher glycidyl ethers (trimethylolethane triglycidyl ether) , Trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, triglycidyl trishydroxyethyl isocyanurate, etc.), tetra- or higher functional glycidyl ethers (sorbitol tetraglycidyl ether, pentaerythritol tetraglycyl ether, polyglycidyl ether of cresol novolac resin, Phenol novolac resin polyglycidyl ether, etc.), alicyclic epoxies (Celoxide 2021P, Celoxy Id 2081, epolide GT-301, epolide GT-401 (manufactured by Daicel Chemical Industries, Ltd.), EHPE (manufactured by Daicel Chemical Industries, Ltd.), phenol novolac resin polycyclohexyl epoxy methyl ether, etc.), oxetane (Such as OX-SQ, PNOX-1009 (manufactured by Toagosei Co., Ltd.)) and the like, but the present invention is not limited thereto.

In the present invention, an alicyclic epoxy derivative can be preferably used. The “alicyclic epoxy group” refers to a partial structure in which a double bond of a cycloalkene ring such as a cyclopentene group or a cyclohexene group is epoxidized with an appropriate oxidizing agent such as hydrogen peroxide or peracid.
As the alicyclic epoxy compound, polyfunctional alicyclic epoxies having two or more cyclohexene oxide groups or cyclopentene oxide groups in one molecule are preferable. Specific examples of the monofunctional or polyfunctional alicyclic epoxy compound include 4-vinylcyclohexene dioxide, (3,4-epoxycyclohexyl) methyl-3,4-epoxycyclohexylcarboxylate, di (3, 4-epoxycyclohexyl) adipate, di (3,4-epoxycyclohexylmethyl) adipate, bis (2,3-epoxycyclopentyl) ether, di (2,3-epoxy-6-methylcyclohexylmethyl) adipate, di And cyclopentadiene dioxide.
One type of alicyclic epoxy compound may be used, or a mixture of two or more types may be used.
Various alicyclic epoxy compounds are commercially available and can be obtained from Union Carbide Japan Co., Ltd., Daicel Chemical Industries, Ltd., and the like.

The glycidyl compound which has a normal epoxy group which does not have an alicyclic structure in a molecule | numerator can be used independently, or it can also use together with said alicyclic epoxy compound.
Examples of such normal glycidyl compounds include glycidyl ether compounds and glycidyl ester compounds, but it is preferable to use glycidyl ether compounds in combination.
Specific examples of the glycidyl ether compound include 1,3-bis (2,3-epoxypropyloxy) benzene, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy. Resin, aromatic glycidyl ether compounds such as trisphenolmethane type epoxy resin, aliphatic glycidyl ether compounds such as 1,4-butanediol glycidyl ether, glycerol triglycidyl ether, propylene glycol diglycidyl ether, trimethylolpropane tritriglycidyl ether Can be mentioned. Examples of the glycidyl ester include glycidyl ester of linolenic acid dimer.
Glycidyl ethers can be obtained commercially from Yuka Shell Epoxy Co., Ltd.

  In the present invention, a compound having an oxetanyl group which is a 4-membered cyclic ether (hereinafter, also simply referred to as “oxetane compound”) can be used. An oxetanyl group-containing compound is a compound having one or more oxetanyl groups in one molecule. This oxetanyl group-containing compound is roughly classified into a monofunctional oxetane compound having one oxetanyl group in one molecule and a polyfunctional oxetane compound having two or more oxetanyl groups in one molecule.

  As the monofunctional oxetane compound, a compound represented by the following formula (6) is preferable.

In the formula (6), R ₁ represents a methyl group or an ethyl group. R ₂ represents a hydrocarbon group having 6 to 12 carbon atoms.
The hydrocarbon group for R ₂ may be a phenyl group or a benzyl group, but is preferably an alkyl group having 6 to 8 carbon atoms, particularly preferably a branched alkyl group such as a 2-ethylhexyl group. Examples of oxetane compounds in which R ₂ is a phenyl group are described in JP-A No. 11-140279. An example of an oxetane compound which is a benzyl group in which R ₂ may be substituted is described in JP-A-6-16804.

  In the present invention, a polyfunctional oxetane compound can be used, but a preferred compound group is represented by the following formula (7).

In formula (7), m represents a natural number of 2, 3 or 4, and Z represents an oxygen atom, a sulfur atom or a selenium atom. R ₃ is a hydrogen atom, a fluorine atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a fluoroalkyl having 1 to 6 carbon atoms, an allyl group, a phenyl group or a furyl group. R ₄ is an m-valent linking group, preferably a group having 1 to 20 carbon atoms, and may contain one or more oxygen atoms and sulfur atoms.
Z is preferably an oxygen atom, R ₃ is preferably an ethyl group, m is preferably 2, and R ₄ is preferably a linear or branched alkylene group having 1 to 16 carbon atoms or a linear or branched poly (alkyleneoxy) group. , R ₃ , R ₄ , Z and m are more preferably compounds obtained by combining any two or more of the preferred examples.

  As the polymerizable monomer (ultraviolet curable binder) of the present invention, it is also preferable to use a radical polymerizable ethylenically unsaturated compound and a cationic polymerizable cyclic ether (epoxy derivative and / or oxetane derivative) in combination. There is an advantage that a bonded body having balanced physical properties can be obtained due to the structure of an interpenetrating polymer network (IPN). In this case, it is preferable to use a radical photopolymerization initiator and a cationic photopolymerization initiator (such as an onium salt) in combination as the photopolymerization initiator.

The volatile component after curing of the polymerizable monomer (ultraviolet curable binder) is preferably 5% by weight or less. For this reason, it is preferable to use a solvent-free formulation that does not use an organic solvent for the binder.
In order to reduce the volatile components after curing, the remaining uncured polymerizable monomer can be post-polymerized by ultraviolet irradiation or heating.

  In the present invention, gamma rays, alpha rays, X rays, ultraviolet rays, visible rays, electron beams and the like can be used as radiation for causing the polymerization of the polymerizable monomer to proceed. Of these, ultraviolet rays and visible rays are preferably used from the viewpoint of cost and safety, and ultraviolet rays are more preferably used.

As a polymerizable monomer, it can also be added for the purpose of viscosity adjustment. As the polymerizable monomer for viscosity adjustment, a compound having a low viscosity and copolymerizable with the polymerizable monomer is used. For example, acrylate, methacrylate, acrylamides can be mentioned. Specifically, tolyloxyethyl (meth) acrylate, phenyloxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, ethylene glycol di (meth) acrylate, divinyl Benzen, methylenebisacrylamide, 1,6-di (meth) acryloyloxyhexane, etc., preferably tolyloxyethyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,6-di (meth) acryloyloxyhexane Etc.
In ring-opening polymerizable cyclic ethers, bifunctional or higher cyclic ethers generally have high reactivity but high viscosity. In order to adjust to low viscosity, monofunctional cyclic ethers can be used in combination.

(Coloring agent)
Colorants that can be used in the polymerizable monomer ink (hereinafter also referred to as ink composition) in the present invention are roughly classified into dyes and pigments, and dyes can be preferably used. More preferably, the dye is an oil-soluble dye. The oil-soluble dye will be described in detail in the section of dispersed ink.

-Dye-
By using yellow (Y), magenta (M) and cyan (C) dyes, which are the three primary colors of the subtractive color method, a wide range of hues can be reproduced with different saturations. In this invention, it is preferable to use the dye utilized for the color print of a color photograph. Details are described below.

As yellow dyes, U.S. Pat. Nos. 3,933,501, 4,022,620, 4,326,024, 4,401,752, 4,248,961, JP-B 58- 10739, British Patents 1,425,020, 1,476,760, U.S. Patents 3,973,968, 4,314,023, 4,511,649, European Patent 249,473A Couplers represented by formulas (I) and (II) of No. 502,424A, and couplers represented by formulas (1) and (2) of No. 513,496A (particularly Y-28 on page 18). A coupler represented by the formula (I) of claim 1 of US Pat. No. 568,037A, a coupler represented by the general formula (I) of lines 45 to 55 of column 1 of US Pat. No. 5,066,576, One of paragraph 0008 of 4-274425 A coupler represented by formula (I), a coupler described in claim 1 on page 40 of European Patent 498,381A1 (particularly D-35 on page 18), and a formula (Y) on page 4 of 447,969A1. Couplers represented (especially Y-1 (page 17), Y-54 (page 41)), US Pat. No. 4,476,219, column 7, lines 36 to 58, formulas (II) to (IV) And ketimine type dyes obtained from the couplers represented (particularly II-17, 19 (column 17), II-24 (column 19)). Preferably, dyes described in JP 2001-294773 A, JP 2002-121414 A, JP 2002-105370 A, JP 2003-26974 A, JP 2003-73598 A, and the like are mentioned. Among these, a pyrazole compound represented by the general formula (Y-II) described in JP-A-2003-73598 is more preferably used.
Y-1 shown below can be preferably used as a yellow dye.

Examples of the magenta dye include dyes described in JP-A Nos. 2001-181549, 2002-121414, 2002-105370, 2003-12981, and 2003-26974. It is done.
Among them, a pyrazolotriazole azomethine compound represented by the general formula (III) described in JP-A No. 2002-121414 is preferably used.
M-1 shown below can be preferably used.

Examples of the cyan dye include dyes described in JP-A Nos. 2002-121414, 2002-105370, 2003-3109, and 2003-26974.
A pyrrolotriazole azomethine compound represented by the general formula (IV-1a) described in JP-A No. 2002-121414 and a phthalocyanine compound represented by the general formulas (C-II-1) and (C-II-2) Preferably used.
C-1 shown below can be preferably used as a cyan dye.

  If necessary, a black (black) dye may be used in combination with the three primary colors of CMY. The black dye can be made by mixing CMY3 dye.

As dyes other than those described above, those generally used in the technical field of printing (for example, color materials for copying or color proofing plates such as printing ink, thermal ink jet recording, and electrophotographic recording) can be used.
For example, “Organization of Organic Synthetic Chemistry” “Dye Handbook” Maruzen Co., Ltd. (published in 1970), Sadaharu Abeda, Kunihiko Kyoto “Commentary Dye Chemistry” Co., Ltd. Examples include dyes described in Kodansha (1986), Chemicals for Inkjet Printers-Material Development Trends and Prospects-"CMC Co., Ltd. (1997), Takeshi Amari" Inkjet Printer Technology and Materials ", etc. .

-Oxidation potential-
As the dye used in the monomer ink in the invention, it is preferable to use an oil-soluble dye having an oxidation potential nobler than 1.0 V (vs SCE). The oxidation potential is preferably as noble, more preferably noble than the oxidation potential of 1.1 V (vs SCE), and most preferably nob of 1.2 V (vs SCE).

  A person skilled in the art can easily measure the value (Eox) of the oxidation potential. Regarding this method, for example Delahay's “New Instrumental Methods in Electrochemistry” (1954, published by Interscience Publishers) and A.D. J. et al. "Electrochemical Methods" by Bard et al. (1980, published by John Wiley & Sons), Akira Fujishima et al., "Electrochemical Measurement Method" (published by Gihodo Publishing Co., Ltd., 1984).

Specifically, the oxidation potential is 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ mol / in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. Approximate the oxidization wave in a straight line by dissolving 1 liter and sweeping to the oxidation side (noble side) using carbon (GC) as the working electrode and rotating platinum electrode as the counter electrode by cyclic voltammetry and DC polarography equipment Then, the intermediate potential of the line segment formed by the intersection of this straight line and the residual current / potential line and the intersection of the straight line and the saturation current line (or the intersection of the straight line parallel to the vertical axis passing through the peak potential value) Values are measured as values for SCE (saturated calomel electrode). Although this value may be deviated by several tens of mil volts due to the influence of the liquid potential difference or the liquid resistance of the sample solution, the reproducibility of the potential can be guaranteed by inserting a standard sample (for example, hydroquinone). The supporting electrolyte and solvent to be used can be selected appropriately depending on the oxidation potential and solubility of the test sample. The supporting electrolytes and solvents that can be used are described in Akira Fujishima et al.
In the concentration range of the measurement solvent and the phthalocyanine compound sample, the oxidation potential in a non-association state is measured.

The value of Eox represents the ease of transfer of electrons from the sample to the electrode, and the larger the value (the higher the oxidation potential), the less transfer of electrons from the sample to the electrode, in other words, less oxidation.
When a dye having a low oxidation potential is used, polymerization inhibition by the dye is large and curability is lowered. When a dye having a noble oxidation potential is used, there is almost no polymerization inhibition.

-Pigment-
The pigment is not particularly limited, and is generally all commercially available organic and inorganic pigments, or pigments dispersed in an insoluble resin or the like as a dispersion medium, or a resin grafted on the pigment surface. A thing etc. can be used. Moreover, what dye | stained the resin particle with dye can be used.

Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable. Therefore, it has a high hiding power and coloring power as a pigment, and further, acid and alkali. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the white pigments listed) may be used depending on the type of powder material and binder component.

In the present invention, CMY pigments may be used instead of CMY dyes.
Specific examples of organic pigments and inorganic pigments include, for example, C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Non-benzidine type azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  As a magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (Perylene Scarlet, etc.); I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

  As a pigment exhibiting a cyan color, C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Phthalocyanine pigments such as C.I. Pigment Blue 15 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

  Examples of the black pigment include carbon black and titanium black.

  The recording medium of the present invention can also be recorded using dispersed ink, pigment ink, water-soluble dye ink, and solvent-based ink.

<Dispersed ink>
The dispersed ink is prepared by mixing at least one oil-soluble dye, at least one oil-soluble polymer, and at least one low-boiling organic solvent (water solubility is 4 g or less) to prepare an oil phase (organic phase). The obtained oil phase is added to water (aqueous phase) and emulsified and dispersed using a homogenizer. The ink is obtained by dispersing colored fine particles containing an oil-soluble dye in an oil-soluble polymer. .
In addition, by adding a water-soluble compound having a hydrophobic group at the end (including a polymer) to the dispersion of the colored fine particles, the aggregation of the colored fine particles (dispersed droplets) is effectively suppressed, and a uniform dispersion state is achieved. Can be kept stable.
The dispersion ink as described above is described in detail in Japanese Patent Application No. 2003-24530, and the dispersion ink described in the specification can be used in the recording method of the present invention.

The oil-soluble dye means a pigment that is substantially insoluble in water, and specifically refers to a pigment having a solubility in water at 25 ° C. (mass of pigment that can be dissolved in 100 g of water) of 1 g or less. The preferable range of this solubility is 0.5 g or less, more preferably 0.1 g or less. The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably 150 ° C. or lower, and particularly preferably 100 ° C. or lower. When the melting point of the oil-soluble dye is low, crystal precipitation of the dye is suppressed, and the dispersion stability of the ink jet recording ink and the storage stability with storage can be improved.
Examples include anthraquinone, naphthoquinone, styryl, indoaniline, azo, nitro, coumarin, methine, porphyrin, azaporphyrin, and phthalocyanine dyes. For full-color printing, at least four colors are usually required, which are black (K) added to the three primary colors of yellow (Y), magenta (M), and cyan (C). Specific examples of these four color pigments and the contents in the ink are those described in paragraphs 0030 to 0213 of the above specification.

  The oil-soluble polymer is polyester or an addition polymer, and the specific examples and the amount added to the oil-soluble dye can be those described in paragraphs 0217 to 0239 of the specification.

The low-boiling organic solvent is added as a solvent for the oil-soluble polymer and oil-soluble dye, and is added to reduce the dispersed particle size of the emulsified dispersion. The low-boiling organic solvent is preferably removed by emulsification and dispersion after heating under reduced pressure or ultrafiltration. The low boiling point organic solvent has a solubility in water of 4 g or less at 25 ° C., preferably 3 g or less, more preferably 2 g or less, and particularly preferably 1 g or less. The boiling point is 100 ° C. or lower, preferably 80 ° C. or lower, particularly preferably 70 ° C. or lower. Specific examples include those described in paragraphs 0295 to 0296 in the above specification.
In addition, a high-boiling organic solvent can be added in order to adjust the glass transition temperature or the like of the oil-soluble polymer or improve the dispersion stability.

  The high-boiling organic solvent is an organic solvent having a boiling point of 200 ° C. or higher and a melting point of 80 ° C. or lower, and particularly preferably has a water solubility of 4 g or lower at 25 ° C. When the water solubility (25 ° C.) exceeds 4 g, the colored fine particles constituting the ink composition are likely to be coarsened or aggregated over time, and have a serious adverse effect on the ink ejection performance. May have an effect. The solubility of the water is preferably 4 g or less, more preferably 3 g or less, still more preferably 2 g or less, and particularly preferably 1 g or less. Specific examples of the high-boiling organic solvent and the addition amount thereof may be those described in paragraphs 0260 to 0293 of the above specification.

The water-soluble polymer having a hydrophobic group at the terminal refers to a polymer in which a hydrophobic group or a hydrophobic polymer is linked to a water-soluble polymer via a divalent linking group having a hetero bond.
The hydrophobic group is an aliphatic group, an aromatic group, an alicyclic group or the like (specifically, those shown in paragraphs 0306 to 0314 of the above specification), and the hydrophobic polymer is polystyrene and its Derivatives, polymethacrylic acid esters and derivatives thereof, polyacrylic acid esters and derivatives thereof, and polyvinyl chloride. The divalent linking group having a hetero bond refers to an ether bond, an ester bond, a thioether bond, a thioester bond, or the like. The water-soluble polymer is at least one of a vinyl alcohol monomer, an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer or an unsaturated phosphonic acid monomer, and further a vinyl ester monomer (vinyl acetate, vinyl formate, propionic acid). A polymer obtained by polymerization from a monomer containing vinyl or the like, or —CH ₂ —C (R) (OH) —CH ₂ —O— (R is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms). And the like.
Specific examples of the water-soluble polymer having a hydrophobic group at the terminal and the content thereof in the ink may be those described in paragraphs 0329 to 0332 of the above specification.
In addition to the components described above, other water-soluble polymers (as described in paragraph 0336 of the specification) and surfactants (as described in paragraph 0337 of the specification) can be used as appropriate when preparing the oil phase.

  The average particle diameter of the dispersed ink is preferably 0.1 μm or less, and particularly preferably 0.01 to 0.1 μm.

<Pigment ink>
The pigment ink is prepared by adding a water-insoluble organic pigment to an aqueous medium containing a surfactant and a dispersion polymer, and then using a hard bead to make it fine by a disperser such as a sand mill or a ball mill. In this pigment ink, the water-soluble polymer having a hydrophobic group at the end described in the description of the dispersion ink is allowed to coexist with the pigment, thereby dispersing the pigment uniformly and stably in the aqueous medium without causing aggregation. be able to. Such a pigment ink is disclosed in detail in Japanese Patent Application No. 2003-24004 and used in the recording method of the present invention. The water-soluble polymer having a hydrophobic group at the terminal and the content in the ink are those described in paragraphs 0023 to 0056 of the above specification, and the usable content in the pigment and ink is the same as that in paragraph 0057 of the specification. And 0058 can be applied.

<Water-soluble dye ink>
The water-soluble dye ink is an ink in which a water-soluble dye is dissolved in an aqueous medium. Water-soluble dye inks are characterized by high transparency and high color density. In addition, water-soluble dyes have good stability in water, but in rare cases, they may gradually precipitate during storage, and when this occurs in the nozzle, clogging occurs. Therefore, as described above, a hydrophobic group or a hydrophobic polymer and —CH ₂ —C (R) (OH) —CH ₂ — as a repeating unit are connected via a divalent linking group having a hetero bond. When a water-soluble polymer linked to a polymer containing O- (R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms) is added to the water-soluble dye ink, precipitation of the dye is suppressed during storage. Therefore, the occurrence of liquid clogging at the nozzle portion is prevented, and even when liquid clogging occurs, the cleaning (cleaning) property at that portion is excellent. Such a water-soluble dye ink is described in detail in Japanese Patent Application No. 2003-1000049, and the water-soluble dye that can be used and the content of the water-soluble dye in the ink are described in paragraphs 0045 to 0056 of the above specification. As for the hydrophobic group-containing water-soluble polymer and the content of the polymer in the ink, those described in paragraphs 0019 to 0043 of the same specification can be applied.

<Solvent ink>
The solvent-based ink is obtained by dissolving an oil-soluble dye in an organic solvent. As the oil-soluble dye, the oil-soluble dye described in the section of the dispersed ink can be used in the same manner. Further, as an organic solvent, a solvent-based ink is described in JP-A 63-60784, page 4, lower right column, line 5 to page 5, lower right column, line 5; The organic solvent described in the second line to the lower left column, line 7 of the same page can be used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” represent “parts by mass” and “mass%” unless otherwise specified, and “average molecular weight” and “degree of polymerization” are “weight average molecular weight” and “weight”. It represents “average degree of polymerization”. In the following operations, all the samples including the polymerization initiator were performed under a yellow lamp.

[Example 1]
(Production of support)
Wood pulp composed of 100 parts of LBKP is beaten to 300 ml Canadian freeness with a double disc refiner, 0.5 parts of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 0.1 part of polyamide polyamine epichlorohydrin, 0.5 part of cationic polyacrylamide All parts were added at an absolutely dry mass ratio with respect to the pulp, and weighed with a long net paper machine to produce a base paper of 170 g / m ² .
In order to adjust the surface size of the base paper, 0.04% of a fluorescent whitening agent (“Whiteex BB” manufactured by Sumitomo Chemical Co., Ltd.) is added to a 4% aqueous solution of polyvinyl alcohol, and this is 0 in terms of absolute dry mass. The base paper was impregnated so as to be 0.5 g / m ² , dried, and then subjected to a calendering process to obtain a base paper adjusted to a density of 1.05 g / ml.

After the corona discharge treatment was performed on the wire surface (back surface) side of the obtained base paper, high-density polyethylene was coated to a thickness of 19 μm using a melt extruder to form a resin layer composed of a mat surface. (Hereinafter, the resin layer surface is referred to as “back surface”). The resin layer on the back side is further subjected to a corona discharge treatment, and then, as an antistatic agent, aluminum oxide (“Alumina sol 100” manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (“Snow manufactured by Nissan Chemical Industries, Ltd.”). A dispersion in which water was dispersed in water at a mass ratio of 1: 2 was applied so that the dry mass was 0.2 g / m ² .

  Furthermore, after the corona discharge treatment is applied to the felt surface (surface) side where the resin layer is not provided, anatase-type titanium dioxide 10%, a trace amount of ultramarine blue, and a fluorescent whitening agent 0.01% (vs. polyethylene) A low-density polyethylene containing MFR (melt flow rate) 3.8 is extruded using a melt extruder to a thickness of 29 μm, and a high gloss thermoplastic resin layer is formed on the surface side of the base paper. (Hereinafter, this high-gloss surface is referred to as a “front side”), which was used as a support.

(Preparation of coating solution for ink receiving layer)
The following ink-receiving layer coating liquid A1 composition was prepared by gradually adding from the top while stirring.
-Composition of ink receiving layer coating liquid A1-
Muticle PP2000TX (acrylic styrene dispersion, solid content concentration: 20%, manufactured by Mitsui Chemicals, average particle size: 0.5 μm, through hole diameter 0.2 μm) 100 parts
Emulgen 109P (polyoxyethylene lauryl ether) 1 part (manufactured by Kao Corporation, HLB value 13.6, solid content concentration: 10% aqueous solution)
Polyvinyl alcohol PVA235 (Kuraray Co., Ltd., solid content concentration: 7%) 14.3 parts thermal polymerization initiator V-59 (2,2′-azobis (2-methylbutylnitrile), manufactured by Wako Pure Chemical Industries, solid content Concentration: 3% methanol solution) 10 parts Ion-exchanged water 12.8 parts

(Preparation of gelling agent solution)
The following gelling agent solution B1 composition was gradually added from the top while stirring.

-Gelling agent solution B1-
Ion-exchanged water 317 parts Boric acid 16.5 parts Ammonium carbonate 17.5 parts Ammonium zirconium carbonate (trade name “Zircosol AC7” manufactured by Nutex Co., Ltd., 13% aqueous solution) (13% aqueous solution) 12.7 parts polyoxyethylene Lauryl ether (nonionic surfactant)
(Emulgen 109P (2% aqueous solution), manufactured by Kao Corporation) 150 parts

  The diameter of the through hole was measured from a scanning electron micrograph of the particle.

(Preparation of inkjet recording material)
The ink-receiving layer coating liquid A1 is applied to the front surface of the support using a hopper type applicator at a coating thickness of a dry film thickness of 25 g / m ² , and dried at 60 ° C. for 2 minutes using a hot air dryer. In a dry state, the gelling agent solution B1 was dip-coated, scraped off with an air knife so that the wet coating amount was 20 g / m ^2, and dried at 60 ° C. for 10 minutes. This produced the inkjet recording material.

[Example 2]
In Example 1, V-501 (2,2-azobis (4-cyanovaleric acid); manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of the thermal polymerization initiator V-59. An ink jet recording material was prepared.

Example 3
(Preparation of emulsion dispersion of polymerization initiator)
1 part of a photopolymerization initiator (1-hydroquine-cyclohexyl-phenyl ketone) was dissolved in a mixed solution of 1 part of dibutyl phthalate and 9 parts of ethyl acetate to obtain a solution I (organic phase). On the other hand, 0.3 part of sodium di (2-ethylhexyl) sulfosuccinate was added to 15 parts of water to obtain a solution II (aqueous phase). After the solution I was added to the solution II and emulsified and dispersed with a homogenizer, 3 parts of a 10% aqueous solution of polyvinyl alcohol PVA105 was added and stirred, desolvated under reduced pressure to remove ethyl acetate, and the polymerization initiator concentration 5% of dispersion D was obtained.
An ink jet recording material was prepared in the same manner as in Example 1 except that 2 parts of the dispersion D was used in place of 10 parts of the 3% methanol solution of the thermal polymerization initiator V-59.

Example 4
Inkjet recording material in the same manner as in Example 1 except that 10 parts of a photopolymerization initiator (4-benzoylbenzyl) 3 wt% sodium sulfonate aqueous solution was used in place of the thermal polymerization initiator V-59. Was made.

Example 5
In Example 1, instead of using the thermal polymerization initiator V-59, 5 parts of a 3% methanol solution of V-501 and 5 parts of a 3% by weight aqueous solution of a photopolymerization initiator (4-benzoylbenzyl) sodium sulfonate were used. In the same manner as in Example 1, an inkjet recording material was produced.

Example 6
(Preparation of coating liquid A2 for ink receiving layer)
The following ink receiving layer coating solution A2 composition was prepared by gradually adding from the top while stirring. Further, the pH of the liquid was adjusted to 7.8 with NaOH (1M) to prepare a desired ink receiving layer coating liquid.

-Composition of coating liquid A2 for ink receiving layer image receiving-
Anionic fine particles (35% dispersion of structural formula A-1 below, pH 6.8) 100 parts Cationic fine particles (35% dispersion of structural formula K-1 below, pH 4.0) 10 parts Emulgen 109P (polyoxyethylene Lauryl ether) 1 part (manufactured by Kao Corporation, HLB value 13.6, solid content concentration: 10% aqueous solution)
Polyvinyl alcohol PVA440 (Kuraray Co., Ltd., solid content concentration: 7%) 15 parts thermal polymerization initiator V-501 (2,2-azobis (4-cyanovaleric acid); manufactured by Wako Pure Chemical Industries, Ltd.),
Solid content concentration: 3% methanol solution) 20 parts Ion-exchanged water 15 parts

  The following gelling agent solution B2 composition was prepared by adding little by little from the top while stirring.

-Composition of gelling agent solution B2-
Ion-exchanged water 303 parts Boric acid 17 parts Ammonium carbonate 17 parts Zirconium carbonate (13%) 13 parts Emulgen 109P (2%) 150 parts

(Preparation of inkjet recording material)
The ink-receiving layer image-receiving coating solution A2 is applied to the front surface of the support using a hopper type coating machine at a coating thickness of 35 g / m ² and dried at 60 ° C. for 2 minutes using a hot air dryer. In a semi-dry state, the gelling agent solution B2 was dip coated, scraped off with an air knife so that the wet coating amount was 20 g / m ^2, and dried at 60 ° C. for 10 minutes. This produced the inkjet recording material.

[Comparative Example 1]
In Example 1, an ink jet recording material was produced in the same manner as in Example 1 except that no polymerization initiator was contained.

(Preparation of monomer ink I)
Monomer ink I was prepared by stirring and mixing the following monomer ink I composition.
-Monomer ink I composition-
Polymerizable monomer: ACMO 20 parts N-ethyldiethanolamine 0.3 part Colorant: M-1 0.8 part

(Preparation of monomer ink II)
The following monomer ink II composition was stirred and mixed to prepare monomer ink II.
-Monomer ink II composition-
Polymerizable monomer: HDDA 20 parts p-tert-butylphenol 0.3 part Colorant: M-1 0.8 part

(Preparation of comparative monomer ink III)
The following monomer ink III composition for comparison was stirred and mixed to prepare a monomer ink III for comparison.
-Comparative monomer ink III composition-
Polymerizable monomer: HDDA 20 parts p-tert-butylphenol 0.3 part Colorant: M-1 0.8 part Photopolymerization initiator: 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide 0.6 part

(Comparison ink IV: Preparation of water-soluble dye-based ink)
The following comparative ink IV composition was stirred and mixed to prepare comparative ink IV.
-Comparative ink IV composition-
Colorant: M-1 4 parts diethylene glycol 9 parts tetraethylene glycol monobutyl ether 9 parts glycerin 7 parts diethanolamine 1 part water 70 parts

[Evaluation test]
The following evaluation was performed for each sample of Examples 1 to 6, the inkjet recording material of Comparative Example 1 obtained above, and a commercially available inkjet photographic paper (manufactured by Seiko Epson Corporation). The test results are shown in Table 1 below.

(1) Average pore diameter (measurement of average pore diameter of ink receiving layer)
Scanning electron microscope (SEM) photograph of the surface of the ink jet recording material (magnification of 10,000 to 100,000 after enlargement) is input to a scanner and digitized, and then subjected to computer image processing, and the extracted area of each void portion The average diameter (number average) of the distribution of the diameters of the circles having the same area as that of the ink receiving layer was determined as the average diameter.

(2) Ink permeability The ink permeability was determined by an automatic scanning liquid absorption meter KM500Win manufactured by Kumagai Ri Industry Co., Ltd., which improved the conventional Bristow method. The measuring method using this apparatus is described in Paper Technology Association Vol. 48, No. 6, pages 88-92. With this apparatus, the amount of ink transferred to the ink jet recording material is measured, and the inclination is determined from the liquid absorption curve (liquid transfer amount versus contact time) obtained from this measurement, so that the ink 30 ml / m ² penetrates. The time required for the ink was calculated to evaluate the ink permeability.

(Printing process)
The monomer ink and the comparative ink prepared as described above were placed in a black cartridge of an inkjet printer LPR5000 (manufactured by Sony Corporation), and solid printing was performed stepwise on the sample (printing speed, 6 seconds / A4).

(Smoothing process)
Next, the surface of the inkjet recording material is adjusted to a temperature of 140 ° C. by superimposing the release agent application surface of the 100 μm polyimide film coated with a silicone resin having releasability and the printing surface of the inkjet recording material. The film was peeled after cooling by heating and pressing through a heat roller. The nip pressure at this time was 20 kg / cm ² .
The glossiness, optical density, nozzle clogging, and image bleeding after the smoothing treatment were measured.

(3) Glossiness of printed surface After the smoothing treatment, the glossiness of the printed surface of the inkjet recording material printed is described in JIS P-8142 (60 ° specular glossiness test method for paper and paperboard, 1993). Measurement and evaluation were performed according to the method.

(4) Optical density The optical density of the inkjet recording material was measured by Xrite 938 (manufactured by Xrite).

(5) Nozzle clogging After 100 sheets of A4 were printed using a Deep UV lamp (SP-7, manufactured by Ushio Co., Ltd.) under the condition of energy of 100 mJ / cm ² under the line head, The state was visually observed and evaluated in the following three stages.
○: No nozzle clogging.
Δ: A part of the nozzle is clogged and linear printing unevenness occurs.
X: More than half of the nozzles were clogged, and printing was impossible.

(6) Image blur After printing a line image and performing post-processing (heat treatment or heat treatment after light irradiation), the image is left to stand in an atmosphere of 25 ° C. and 80% RH for one week to observe bleeding. It was evaluated in three stages.
○: No bleeding.
Δ: Slight bleeding and thick line.
X: Large blur and lines are largely blurred.

As is apparent from the evaluation results of the recording material shown in Table 1, Experiment No. 1 using the recording material of the present invention was used. Nos. 1 to 7 are good in all items. 8 to 11 indicate that any item is defective.
As is apparent from the evaluation results of the recording method in Table 2, Experiment No. which is the recording method of the present invention. Nos. 1 to 7 are good in all items. 8 to 13 indicate that any item is defective. In particular, Experiment No. When a recording medium without a polymerization initiator is used for the ink receiving layers 8 and 9, the printed monomer ink does not polymerize, and the colorant is transferred to the film side during the heat treatment (during the glossing process). It can be seen that the optical density of the recording material is lowered at the same time. It can also be seen that blurring of the image is likely to occur during storage.
From these, the recording method of the present invention for printing using the recording medium of the present invention and the monomer ink that does not contain a polymerization initiator does not cause clogging of the nozzles, and is a high-gloss, non-bleeding, high-quality image. You can see that It can also be seen that the ink permeability is high, so that it can cope with high-speed printing.

It is a figure which shows an example of the heating roll used for the smoothing process in the recording method of this invention. It is a figure which shows an example of the heating belt and pressure roll used for the smoothing process in the recording method of this invention.

Explanation of symbols

10, 20 rolls 16, 48 heating means 30 recording medium 40 heating belt 42 belt 44 heating roll 50 pressure roll

Claims (14)

A recording medium comprising an ink receiving layer containing a polymerization initiator on a support, and the ink receiving layer is a porous layer containing organic fine particles. The recording medium according to claim 1, wherein the polymerization initiator is a photopolymerization initiator and / or a thermal polymerization initiator. The recording medium according to claim 1, wherein an average pore diameter of the porous layer is 0.01 to 10 μm. The recording medium according to claim 1, wherein the ink receiving layer is thermoplastic. The recording medium according to claim 1, wherein the organic fine particles are through-hole type particles. The recording medium according to claim 1, wherein the organic fine particles are styrene and / or allyl based particles. The recording medium according to claim 1, wherein the organic fine particles are organic fine particles having a positive charge and organic fine particles having a negative charge. The recording medium according to claim 7, wherein at least one of the organic fine particles having a positive charge and the organic fine particles having a negative charge is weakly charged. The recording medium according to claim 1, wherein the recording medium is for inkjet recording. A recording method comprising: printing on a recording medium according to any one of claims 1 to 9 using an ink containing a polymerizable monomer without containing a polymerization initiator. The recording method according to claim 10, further comprising heating the recording medium after printing. The recording method according to claim 10, wherein the recording medium after printing is further heated after light irradiation. The recording method according to claim 10, wherein the recording medium after printing is further heated simultaneously with light irradiation. The recording method according to claim 11, wherein the heating is performed under pressure.

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