JP2005119217A - Inkjet recording material and inkjet image forming method using the same - Google Patents

Abstract

The present invention provides an inkjet image excellent in ink absorbability and image sharpness in an inkjet recording system, and has high gloss, good ozone resistance, and recording even when the amount of ink adhering greatly differs between the front and back sides. An object of the present invention is to provide an ink jet recording material having good curl characteristics later.
In an inkjet recording material provided with an inkjet recording layer containing a mixture of inorganic ultrafine particles and thermoplastic organic polymer fine particles on both sides of a support, the average secondary particle size of the inorganic ultrafine particles is 300 nm or less. The average particle diameter of the thermoplastic organic polymer fine particles on one side of the support is 300 nm or less, and the average particle size of the thermoplastic organic polymer fine particles on the other side of the support is 0.1 μm or more and 10 μm or less. An ink jet recording material. Also, an inkjet image forming method for providing an inkjet recording material having further excellent gloss and ozone resistance by heating after image formation.
[Selection figure] None.

Description

  The present invention relates to an ink jet recording material and an ink jet image forming method using the same, and is excellent in ink absorbability and image sharpness, excellent in glossiness and ozone resistance, and further has changed printing conditions on both sides. Even in this case, the present invention relates to an ink jet recording material exhibiting good curling properties after recording and an ink jet image forming method using the same.

  The ink jet recording method is a method in which micro droplets of ink are ejected and adhered to a recording material such as paper by various operating principles to record images, characters, etc. It has features such as easy recording pattern flexibility and no need for development-fixing, and is rapidly spreading in various applications as a recording apparatus for various figures and color images including Chinese characters. In addition, images formed by the multi-color ink jet method can be recorded inferior to multi-color printing by the plate making method and printing by the color photographic method, and the number of created copies is small. Because it is less expensive than photographic technology, it is widely applied to the field of full-color image recording.

  Efforts have been made from the aspect of apparatus and ink composition to use high-quality paper and coated paper used for normal printing and writing as recording materials used in the ink jet recording system. However, with the improvement in performance and expansion of applications of the ink jet recording apparatus such as high speed, high definition or full color of the apparatus, more advanced characteristics are required for the recording material. That is, as the recording material, the density of the printed dots is high, the color tone is bright and vivid, the ink does not flow out or bleed even when the ink is absorbed quickly and the printed dots overlap, and the side of the printed dots It is required that the diffusion in the direction is uniform and not larger than necessary, the periphery is smooth and unblurred, the image quality does not change over time and in the environment, for example, has excellent ozone resistance.

  Several proposals have been made for such a demand. For example, by providing an ink jet recording layer mainly composed of inorganic ultrafine particles, an ink jet recording material excellent in gloss and ink absorbability has been proposed.

  Examples of inorganic ultrafine particles include colloidal silica such as spherical, beaded, and cation-modified, silica synthesized by a gas phase method, alumina hydrate such as amorphous, boehmite, and pseudoboehmite, silica / alumina hybrid sol, and smectite. Various things such as clay are known.

  However, the disadvantages of such inorganic ultrafine particles are that the fading of the pigment due to ozone, light, etc. is likely to proceed, and that the storage stability such as ozone resistance is poor, and these problems have not yet been solved. .

  On the other hand, the diversification of uses of inkjet recording materials has led to the single-sided type being the mainstream, but in recent years the application field of the double-sided type has increased. Supply requirements for double-sided record documents, correspondence postcards, double-sided photographs, double-sided brochures, and advertisements. In response to this market requirement, each inkjet recording material manufacturer has developed and started supplying double-sided ink-jet recording materials of double-sided mat type, single-sided mat single-sided high gloss type, and single-sided mat single-sided semi-gloss type. However, development of the double-sided glossy inkjet recording material, which is particularly demanded for color applications, has been delayed due to the problem of manufacturing technology that makes stable production difficult.

  In addition, the conventional double-sided ink jet recording paper has insufficient curl improvement. In the ink jet recording paper described in Japanese Patent Laid-Open No. 9-286166 (Patent Document 1), by changing the dot diameter formed by the same amount of ink droplets on the front and back sides, the ink amount is not changed. The curl has been improved by making it possible to change only the resolution. However, when printing is performed on only one side or when the amount of ink printed on the front and back is significantly different, the printed matter can be changed to high or low temperature, high humidity or low humidity. When left underneath, there was a problem of curling (environmental curling).

As for the improvement of the environmental curl, Japanese Patent Application Laid-Open No. 2002-29147 (Patent Document 2) proposes an ink jet recording paper having a structure in which at least an inorganic fine particle layer and a thermoplastic fine particle layer are laminated on both sides of a support. It is said that curling can be suppressed even when the amount of ink changes by providing a thermoplastic fine particle layer on the upper part of the layer to prevent the inorganic fine particle layer from spreading due to ink absorption. It is difficult to balance the amount of coating due to the complicated structure of coating, and it is difficult not only to improve curl depending on the environmental conditions, but also when the thermoplastic fine particle layer is densified by heating after printing. Since bubbles in the fine particle layer are mixed and a sufficiently dense film is not formed, such a multilayer structure is inferior in gloss and ozone resistance. There has been a problem that.
JP-A-9-286166 JP 2002-29147 A

  In the ink jet recording method, the ink jet recording system can provide an ink jet image having sufficient ink absorbability, image sharpness, high gloss and ozone resistance even in the case of a single layer, and when the printing conditions are changed on the front and back sides. However, the present invention relates to an ink jet recording material having good curling characteristics after recording and an ink jet image forming method using the same.

The object of the present invention has been basically achieved by the following ink jet recording material.
(1) In an inkjet recording material provided with an inkjet recording layer containing a mixture of inorganic ultrafine particles and thermoplastic organic polymer fine particles on both sides of a support, the average secondary particle diameter of the inorganic ultrafine particles is 300 nm or less, The average particle diameter of the thermoplastic organic polymer fine particles on one side of the support is 300 nm or less, and the average particle size of the thermoplastic organic polymer fine particles on the other side of the support is 0.1 μm or more and 10 μm or less. Achieved by the featured inkjet recording material.
(2) The mass ratio of the inorganic ultrafine particles / thermoplastic organic polymer fine particles in the ink jet recording layer is preferably 2 or more and 20 or less.
(3) After printing on the ink jet recording material, the ink jet recording material is heated to densify the thermoplastic organic polymer fine particles to obtain a highly glossy ink jet recording material having further excellent ozone resistance. Image forming method.
(4) In the above-described inkjet image forming method, the heating densification method is a heating densification method by passing between heated and pressurized rolls, and the pressure applied to the inkjet recording material by the pressurized rolls Is an inkjet image forming method having a surface pressure of 0.1 to 2.5 MPa.

  According to the present invention, in an inkjet recording material provided with an inkjet recording layer containing a mixture of inorganic ultrafine particles and thermoplastic organic polymer fine particles on both sides of a support, the average secondary particle diameter of the inorganic ultrafine particles is 300 nm or less. In addition, the average particle diameter of the thermoplastic organic polymer fine particles is different between the front and back surfaces, and even when the ink adhesion amount is greatly different between the front and back surfaces, the curl characteristics after printing are good, and further, the ink is heated after printing. Since the inorganic ultrafine particles in the recording layer are coated with a molten resin, an ink jet recording material having extremely good gloss and ozone resistance, and excellent image quality and ink absorbability can be obtained. In addition, since both sides can be configured as a single layer, it is quite advantageous in terms of production process and is industrially useful.

  Hereinafter, the ink jet recording material of the present invention and the ink jet image forming method using the same will be described in detail.

  As the support for the recording material, any conventionally known one can be used. For example, a) chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, DIP Mainly composed of natural pulp such as used paper pulp and other conventionally known pigments and mixed with one or more kinds of additives such as binders, sizing agents, fixing agents, yield improvers, cationizing agents, and paper strength enhancing agents. Non-coated papers made from various slurries using various types of equipment such as long net paper machines, circular net paper machines, and twin wire paper machines;

  b) Coated paper such as starch, polyvinyl alcohol, size press or anchor coat layer on non-coated paper, art paper, coated paper, cast coated paper, etc. with a coat layer on them Kind;

  c) Non-coated paper that has been smoothed using a calendar device such as a machine calendar, a TG calendar, or a soft calendar;

  d) Resin-coated papers coated with high density or low density polyethylene, polypropylene, polyester, etc. on both sides or one side of non-coated paper or coated paper by a melt extrusion method or the like;

  e) Transparent synthetic resin films such as polyethylene terephthalate, polypropylene, polyethylene, polyester, polycarbonate, polyvinyl acetate, polyvinyl alcohol and the like, and translucent synthetic resin films containing these materials containing pigments, foaming agents, etc. to reduce transparency;

  f) Mixing thermoplastic resin such as polyethylene, polypropylene, ethylene / propylene copolymer, ethylene / vinyl acetate copolymer, polystyrene, acrylates, and inorganic pigments such as calcium carbonate, talc, silica, calcined clay, etc. Stretched laminated synthetic paper, etc .;

  g) or those having improved adhesion properties such as corona discharge treatment, flame treatment, plasma treatment, anchor layer coating treatment on the surface of the support can be suitably used.

Further, these supports can be subjected to a calendar process such as a machine calendar, a super calendar, a gloss calendar, a matte calendar, a friction calendar, and a brush calendar. The basis weight of the support is usually about 50 to 300 g / m ² .

  Examples of the ultrafine inorganic particles used in the present invention include various types such as silica synthesized by a gas phase method, alumina hydrates such as amorphous, boehmite, and pseudoboehmite, silica / alumina hybrid sol, and smectite clay. As long as the secondary average particle diameter is 300 nm, any of them is suitably used, but alumina fine particles and vapor-phase method silica are particularly preferable in terms of ink absorbability and image sharpness.

  Various alumina compounds are used as the alumina fine particles. In general, by heating aluminum hydroxide such as dibsite, bayerite or boehmite, its crystal form is changed to χ → κ → α, γ → δ → θ → α, η → θ → α, ρ → η → θ → α or pseudo. It is known that the particle size can be grown by transitioning to α-alumina through various intermediate aluminas such as γ → θ → α (for example, Electrochemistry, Vol. 28 (1960), p302, Funaki / Shimizu; Regarding alumina hydrate and alumina, refer to the thermal change example of alumina hydrate). It is also known that by thermally decomposing aluminum salts such as aluminum chloride, aluminum sulfate, and aluminum nitrate, it is possible to transition from amorphous alumina to α-alumina through intermediate alumina such as γ-, δ-, or θ-. (For example, see Journal of Mineralogy, Vol. 19, No. 1 (1990), p21, p41). The alumina fine particles contained in the ink jet recording material of the present invention are selected from δ- or γ-alumina, and the average secondary particle diameter may be particles having a size of 300 nm or less, and the shape thereof is not particularly limited.

A homomixer, ultrasonic homogenizer, pressure homogenizer, nanomizer, high-speed rotary mill, roller mill, container drive medium mill, medium agitation mill, jet mill, sand grinder, etc. are used to disperse, pulverize and beat the alumina fine particles. However, in order to disperse or pulverize more effectively, it is preferable to use a pressure dispersion method. Moreover, it is efficient to add an acid such as acetic acid, nitric acid, lactic acid or hydrochloric acid. In the present invention, the pressure dispersion method is a method in which a slurry mixture of raw material particles is continuously passed through an orifice at a high pressure and pulverized under high pressure, and the treatment pressure is from 19.6 × 10 ^{6 to} 343.2 × 10. ⁶ Pa, more preferably 49.0 × 10 ^{6 to} 245.3 × 10 ⁶ Pa, and still more preferably 98.1 × 10 ^{6 to} 196.2 × 10 ⁶ Pa. Good dispersion or pulverization can be achieved by the above high-pressure pulverization. It is more preferable to use a dispersion or pulverization method in which the slurry-like mixture that has passed through the orifice at a high pressure collides with each other. In the opposite collision method, the dispersion liquid is pressurized and guided to the inlet side, the dispersion liquid is branched into two passages, and the flow path is narrowed by the orifice, thereby accelerating the flow velocity and colliding particles by colliding with each other. And pulverize. As a material constituting the portion where the dispersion is accelerated or collided, diamond is preferably used for the reason of suppressing wear of the material. As the high-pressure pulverizer, a pressure homogenizer, an ultrasonic homogenizer, a micro fullizer, and a nanomizer are used, and a micro fullizer and a nanomizer are particularly preferable as the high-speed collision type homogenizer.

In addition, alumina hydrate fine particles can be selected as the alumina fine particles of the present invention, and can be represented by the following general formula.
Al ₂ O ₃ · nH ₂ O
Alumina fine particles are classified into gypsite, bayerite, norstrandite, boehmite, boehmite gel (pseudoboehmite), diaspore, amorphous amorphous, etc., depending on the difference in composition and crystal form. Among them, boehmite and pseudoboehmite represent alumina fine particles having a boehmite structure when the value of n in the above formula is 1, and represent alumina fine particles having a pseudoboehmite structure when n is more than 1 and less than 3. When n is 3 or more, alumina fine particles having an amorphous structure are represented. Preferred alumina fine particles are alumina fine particles having a pseudo boehmite structure in which at least n is greater than 1 and less than 3.

In order for the xerogel composed of alumina fine particles to have a sufficient ink absorption capacity, the pore volume of the xerogel is preferably in the range of 0.3 to 0.8 ml / g, in particular 0.4 to 0.6 ml. / G is preferable. When the pore volume of the ink receiving layer is large, the ink receiving layer is cracked or powdered, and when the pore volume is small, ink absorption is delayed. Further, the solvent absorption amount of the ink receiving layer per unit area is preferably 5 ml / m ² or more, more preferably 10 ml / m ² or more. When the solvent absorption amount per unit area is small, the ink may overflow particularly when multicolor printing is performed.

In order for the alumina fine particles to sufficiently absorb and fix the dye in the ink, the BET specific surface area is preferably in the range of 70 to 300 m ² / g. When the BET specific surface area is too large, the pore size distribution is shifted toward the smaller side, the fixing efficiency of the dye in the ink is deteriorated, and image blurring occurs. Conversely, if the BET specific surface area is too small, it becomes difficult to disperse the alumina fine particles.

  The shape of the alumina fine particles may be any of a flat plate shape, a fiber shape, a needle shape, a spherical shape, a rod shape, and the like, and a preferable shape is a flat plate shape from the viewpoint of ink absorbability. The plate-like alumina fine particles have an average aspect ratio of 3 to 8, and preferably an average aspect ratio of 3 to 6. The aspect ratio is expressed as the ratio of the “diameter” to the “thickness” of the particles. Here, the diameter of the particle represents the diameter of a circle equal to the projected area of the particle when the alumina fine particle is observed with an electron microscope. When the aspect ratio is smaller than the above range, the pore diameter distribution of the ink receiving layer becomes narrow, and the ink absorbability is lowered. On the other hand, when the aspect ratio exceeds the above range, it is difficult to produce alumina fine particles by aligning the particles.

  The alumina fine particles can be produced by a known method such as hydrolysis of an aluminum alkoxide such as aluminum isopropoxide, neutralization of an aluminum salt with an alkali, or hydrolysis of an aluminate. The particle diameter, pore diameter, pore volume, specific surface area, number of surface hydroxyl groups and the like of the alumina fine particles can be controlled by the precipitation temperature, aging time, liquid pH, liquid concentration, coexisting salts and the like.

  As methods for obtaining the alumina fine particles, JP-A-57-88074, JP-A-62-256321, JP-A-4-275717, JP-A-6-64918, JP-A-7-10535, and JP-A-7-267633. No. 2, U.S. Pat. No. 2,656,321, Am. Ceramic Soc. Bull. 54, 289 (1975), etc. disclose a method for hydrolyzing aluminum alkoxide. Examples of the aluminum alkoxide include isopropoxide, propoxide, 2-butoxide and the like.

  As other methods for obtaining alumina fine particles, inorganic salts of aluminum as exemplified in JP-A Nos. 54-116398, 55-23034, 55-27824, and 56-120508 are exemplified. Or the method of obtaining the hydrate as a raw material is common. Examples of these inorganic salts include aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride, ammonium alum, sodium aluminate, potassium aluminate, aluminum hydroxide and the like and hydrates thereof.

  The vapor-phase process silica used in the present invention is also called a dry process, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase method silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and can be obtained.

  The average particle diameter of the primary particles of the vapor phase silica used in the present invention is 50 nm or less, preferably 5 to 30 nm. The average secondary particle diameter is 300 nm or less. Colloidal silica produced by a wet method has a very small primary particle size of several nm to several tens of nm. However, since the particles are isolated as primary particles, the particles exist in a dense state when a coating film is formed. When used in the receiving layer, the ink absorbability is lowered due to poor porosity. Further, secondary agglomerated silica particles of several μm to several tens of μm have high ink absorptivity, but deteriorate the image quality. On the other hand, the gas phase method silica of the present invention is characterized in that the primary particles are present in a secondary aggregated state connected to a network structure or chain, thereby obtaining high ink absorbability. Further, since the primary particle diameter is very small, a high-quality image can be obtained.

  The average secondary particle diameter of the inorganic ultrafine particles used in the present invention is measured by a dynamic light scattering method. The dynamic light scattering method is a method in which light emitted from a semiconductor laser is irradiated onto particles in a dispersion medium, and the particle diameter is analyzed from the light reflected from the particles. The size of the aggregated particles is obtained. Things come out. The average secondary particle diameter by the dynamic light scattering method was measured using a dynamic light scattering particle diameter measuring device Coulter N4 (manufactured by Coulter).

  The ink jet recording layer containing the inorganic ultrafine particles used in the present invention may contain other inorganic or substantially non-thermoplastic organic fine particles within 20 parts by mass with respect to 100 parts by mass of the inorganic ultrafine particles. I can do it.

  Conventionally known various pigments can be used as the inorganic or organic fine particles. For example, silica (colloidal silica, wet process amorphous silica), aluminum silicate, magnesium silicate, magnesium carbonate, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, sulfide Examples include inorganic pigments such as zinc, zinc carbonate, satin white, diatomaceous earth, calcium silicate, aluminum hydroxide, lithopone, zeolite, hydrous halloysite, and magnesium hydroxide, and organic pigments such as microcapsules, urea resins, and melamine resins. be able to.

  The thermoplastic organic polymer fine particles used in the ink jet recording layer of the present invention include maleic anhydride resin, conjugated diene copolymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer; Acrylic polymer latex such as a polymer or copolymer of methacrylic acid ester, a polymer or copolymer of acrylic acid and methacrylic acid; a vinyl polymer latex such as ethylene vinyl acetate copolymer; A functional group-modified polymer latex or the like with a functional group-containing monomer such as a carboxyl group can be used alone or in combination.

  Since the average particle diameter of the thermoplastic organic polymer fine particles used in the ink jet recording layer on one side of the support is as extremely small as 300 nm or less, light in the low wavelength region (about 400 nm) of visible light is mostly scattered. Therefore, the transparency of the obtained image is improved, and a clear image can be obtained, which is particularly suitable for forming a photographic image having a large amount of ink adhesion. The average particle diameter of the thermoplastic organic polymer fine particles is also a value measured by a dynamic light scattering method similar to that of the inorganic ultrafine particles.

  The thermoplastic organic polymer fine particles having an average particle diameter of 300 nm or less are preferably anionic or cationic. Such polymer fine particles usually contain at least one monomer selected from the group consisting of alkyl acrylate, alkyl methacrylate, styrene and styrene derivatives, and one or more carbon-carbon double bonds in the molecule. It can be obtained by emulsion polymerization using an emulsifier (preferably 2 or more).

  As an example of the alkyl acrylate ester and the alkyl methacrylate ester, an alkyl (meth) acrylate having 1 to 18 carbon atoms is preferable, for example, methyl (meth) acrylate, ethyl (meth) acrylate, ( N-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate Can be mentioned. Examples of styrene and styrene derivatives include styrene, α-methylstyrene and vinyltoluene.

  In addition to the monomer, a monomer copolymerizable with the monomer may be used in an amount of 50% by mass or less of the total monomer amount. For example, anionic vinyl monomers such as acrylic acid, methacrylic acid, maleic anhydride, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and quaternary Cationic vinyl monomers such as vinyl monomers having ammonium salts; and nonionic vinyl monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and (meth) acryloyloxyphosphate Can do.

  In addition to the above monomers, a crosslinkable vinyl monomer may be used in an amount of 5% by mass or less of the total monomer amount. For example, bifunctional monomers such as ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, hexamethylenebis (meth) acrylamide, divinylbenzene; 1,3,5-triacryloylhexahydro-S-triazine And trifunctional monomers such as triallyl isocyanurate; tetrafunctional monomers such as tetramethylolmethane tetraacrylate and N, N, N ′, N′-tetraallyl-1,4-diaminobutane.

Examples of the carbon-carbon double bond of the emulsifier having one or more (preferably two or more) carbon-carbon double bonds in the molecule include a (meth) allyl group and a 1-propenyl group. , 2-methyl-1-propenyl group, vinyl group, isopropenyl group and (meth) acryloyl group. Of these, a (meth) acryloyl group is preferred. The emulsifier has a cationic group or an anionic group (hydrophilic group) for exhibiting an emulsifying action together with a hydrophobic group. A cationic group is preferable because it has a large function of holding ink and thus improves the water resistance of the colorant-receiving layer. Examples of the cationic group or anionic group (hydrophilic group) include —COOH, —COOM, —OSO ₃ M, —N (R ¹ ) (R ² ) (R ³ ), —OH, —PO (OM) _2. , (—O) ₃ P, (—O) ₂ P (OH) —, —OP (OH) ₂ , —OPO (OM) ₂ , (—O) ₂ PO (OM), (—O) ₃ PO and -(OR)-[wherein M represents Na or K, R ¹ , R ² and R ³ each independently represents a hydrogen atom, alkyl, aralkyl or hydroxyalkyl, and R represents ethylene or propylene] Can be mentioned. Among these, —N (R ¹ ) (R ² ) (R ³ ) [R ¹ , R ² and R ³ each independently represents a hydrogen atom, alkyl or hydroxyalkyl, and at least one group is alkyl or Is a hydroxyalkyl group]. The emulsifier plays the role of a normal emulsifier and the role of a polymerizable (crosslinkable) monomer. Therefore, the surface of the obtained polymer fine particle has the above cationic group or anionic group. Of course, it may exist inside the polymer fine particles.

  Examples of emulsifiers include sulfooxysuccinic acid ester salts of polyoxyethylene alkyl ether having two or more carbon-carbon double bonds in the molecule, polyoxyethylene having two or more carbon-carbon double bonds in the molecule. Sulfuric acid ester salt of alkyl ether, polyoxyethylene alkyl phenyl ether sulfosuccinate having two or more carbon-carbon double bonds in the molecule, polyoxy having two or more carbon-carbon double bonds in the molecule Of sulfuric acid ester salt of ethylene alkylphenyl ether, acidic phosphoric acid (meth) acrylic acid ester dispersant, oligoester (meth) acrylate phosphoric acid ester or alkali salt thereof, and polyalkylene glycol derivative having hydrophilic alkylene oxide group Oligoester poly (meth) acrylate Mention may be made of the door. These commercially available products include KAYAMER PM-2 (manufactured by Nippon Kayaku Co., Ltd.), New Frontier A-229E (Daiichi Kogyo Seiyaku Co., Ltd.), New Frontier N-250Z (Daiichi Kogyo Seiyaku). For example).

  When using an emulsifier having two or more carbon-carbon double bonds in the molecule, the emulsifier having one carbon-carbon double bond in the molecule is contained in a proportion of 60% by mass or less of the total emulsifier. Also good. The emulsifier having one or more carbon-carbon double bonds in the molecule may contain a normal anionic emulsifier, a cationic emulsifier, or a nonionic emulsifier. The addition amount of the emulsifier having one or more carbon-carbon double bonds in the molecule is usually 1 to 20 parts by mass with respect to 100 parts by mass of the total monomers, and 3 to 10 parts by mass. preferable.

  The thermoplastic organic polymer fine particles of the present invention can be obtained by a known emulsion polymerization method using the above materials. For example, the emulsifier and water are added to a reaction vessel, and the monomer is added to emulsify the mixture. Then, a radical polymerization initiator is added, and the monomer is polymerized by heating with stirring to polymerize the thermoplastic organic polymer. Fine particles can be obtained. Addition of the vinyl monomer may be either batch dropping or divided dropping. The concentration of such a material is such that the solid content concentration in the finally obtained reaction liquid (dispersion) is usually 20 to 50% by mass, preferably 30 to 45% by mass. Adjusted. The pH during the reaction is preferably in the range of 3 to 9, and the reaction temperature may be any temperature at which the polymerization initiator is activated, and is usually 40 to 90 ° C, preferably 50 to 80 ° C. The reaction time is usually 30 minutes to 2 hours.

  Examples of the radical polymerization initiator include water-soluble radical polymerization initiators such as persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, and water-soluble azo initiators; or the above-mentioned persulfates and hydrogen sulfite. The redox polymerization initiator which combined reducing agents, such as sodium and sodium thiosulfate, can be mentioned. Redox polymerization initiators are preferred. The addition amount of the radical polymerization initiator is preferably 0.05 to 5% by mass, particularly preferably 0.1 to 3% by mass, based on the total monomer amount. Further, in order to make the obtained polymer fine particles into transparent ultra fine particles, it is preferable to carry out the polymerization in the presence of a transition metal ion as a polymerization accelerator. The thermoplastic organic polymer fine particles thus obtained by the emulsifier thus obtained are present on the surface in a state in which the emulsifier is bonded to the particles by polymerization. For this reason, an anionic group, a cationic group ( A hydrophilic group) will be present. Therefore, the inkjet water-based ink can be easily adsorbed on the surface, and an anionic group, a cationic group, etc. can work effectively. Such hydrophilic groups are also present inside the thermoplastic organic polymer fine particles depending on the type, amount, and reaction method of the emulsifier used.

  The average particle diameter of the thermoplastic organic polymer fine particles used in the ink jet recording layer on the other surface of the support is preferably 0.1 μm or more and 10 μm or less. It is suitable for printing character information or the like with less ink adhesion than the above-mentioned surface. When the average particle size of the thermoplastic organic polymer fine particles is less than 0.1 μm, environmental curling is likely to occur if the amount of ink adhering on the front and back surfaces is different, and when the average particle size of the thermoplastic organic polymer fine particles exceeds 10 μm Ink dots are not uniform, and printability may be deteriorated.

  Furthermore, adding an ultraviolet absorber, an antioxidant, a release agent, a light stabilizer, etc., which are usually used for thermoplastic organic polymers, prevents deterioration of the formed thermoplastic organic polymer film. Desirable to improve the light fastness of dyes in inkjet images.

  In the present invention, the mass ratio of inorganic ultrafine particles / thermoplastic organic polymer fine particles in the ink jet recording layer is preferably 2 or more and 20 or less. If this ratio is less than 2, the ink absorbability deteriorates. On the other hand, if this ratio exceeds 20, the gloss and ozone resistance when the thermoplastic organic polymer fine particles are coated by heat treatment are deteriorated, or the image becomes dull depending on the selected inorganic ultra fine particles. It may get worse. The inorganic ultrafine particles are preferably in the range of 20 to 80% by mass with respect to the total solid content of the ink jet recording layer. If the amount is less than 20% by mass, the ink absorbability deteriorates. Sex worsens. Further, the thermoplastic organic polymer fine particles are preferably in the range of 2 to 30% by mass with respect to the total solid content of the ink jet recording layer, and if it is less than 2% by mass, the gloss and ozone resistance tend to deteriorate, If it exceeds 30% by mass, the ink absorptivity tends to decrease.

The minimum film formation temperature of the thermoplastic organic polymer fine particles is preferably 60 ° C. or higher and 150 ° C. or lower. The minimum film forming temperature referred to in the present invention is a temperature at which thermoplastic organic polymer fine particles change from a particulate form to a continuous film by heating, and was measured as follows. First, an aqueous dispersion of thermoplastic organic polymer fine particles was uniformly applied onto a PET film so as to have a dry solid content of 5 g / m ² to obtain a measurement sample. Secondly, a commercially available laminator was passed through the measurement sample through a silicone release film at a speed of 18 cm / min at different temperature levels, and the lowest temperature at which it was considered that a continuous film was formed was defined as the lowest film formation temperature. . The criteria for forming a continuous coating are 1) the coating layer becomes transparent, 2) the coating layer becomes smooth, and 3) the fallen material from the coating layer obtained by rubbing the surface with a sharp instrument is not a discontinuous material. It was decided to satisfy the three items of being a continuous film. If the minimum film-forming temperature is lower than 60 ° C., high-temperature drying becomes impossible at the time of drying after coating the ink jet recording layer, and the operability is remarkably lowered or the ink absorbability is deteriorated. If the minimum film forming temperature is higher than 150 ° C., a high temperature is required to form a film, the support may be distorted or destroyed by heat, and the glossiness and ozone resistance are likely to be reduced. It is not preferable.

  The ink jet recording layer used in the present invention may contain a polymer compound as a binder. As the preferred polymer compound, any compound may be used as long as it functions as a protective colloid for the pigment and has an affinity for the ink as the ink jet recording layer.

  Examples of the binder include polyvinyl alcohol, polyvinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, casein, gelatin, soybean protein, silyl-modified polyvinyl alcohol, melamine resin, urea resin and the like. An aqueous binder such as a thermosetting synthetic resin system can be used, and at least one kind can be used. A cationic resin added for the purpose of fixing a conventionally known dye can also be used in combination.

The total amount of the binder can be appropriately adjusted in accordance with the characteristics of the target inkjet recording material, but generally 5 to 60% by mass with respect to 100% by mass of the inorganic pigment and other inorganic or organic fine particles. It is. The ink jet recording layer as coating weight (dry ^{solids), 5g / m 2 ~50g /} m 2 is preferred. Furthermore, as other additives, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, coloring dyes, coloring pigments, fluorescent whitening agents, Ultraviolet absorbers, antioxidants, preservatives, antibacterial agents, dye fixing agents (cationic polymers), wet paper strength enhancers, dry paper strength enhancers, cross-linking agents, and the like can be appropriately blended.

  As a method for coating these ink jet recording layers, various blade coaters, roll coaters, air knife coaters, bar coaters, rod coaters, gate roll coaters, curtain coaters, short dwell coaters, gravure coaters, flexographic gravure coaters, size presses, Various apparatuses such as a film transfer roll coater and a slide hopper system can be used on-machine or off-machine.

  In addition, after coating, a calendar such as a machine calendar, a heat calendar, a super calendar, or a soft calendar may be used for finishing.

  The ink jet recording material of the present invention provides an ink jet recording material that is sufficiently excellent in image sharpness and ink absorbency by recording an ink jet recorded image. However, after the ink jet recording, the ink jet recording material is further heated. By dissolving or melting the thermoplastic organic polymer fine particles to form a film, the voids in the ink jet recording layer are further filled with the film forming treatment to obtain an ink jet recording material having high gloss and excellent ozone resistance. I can do it.

  The image forming method for obtaining an image by heating and densifying the thermoplastic fine particles by heating the recording material recorded by inkjet recording in the present invention may be performed at a temperature equal to or higher than the minimum film forming temperature of the thermoplastic fine particles. There are no particular restrictions. Heating may be performed from the front or back surface of the recorded material, or from both surfaces. Moreover, you may use together a pressurization process at the time of heat processing. At this time, since melting by heat treatment is promoted by pressure treatment, densification of the resin is promoted, and the treatment can be performed in a shorter time. Preferably, a roll-shaped hot roll used for laminating or the like is passed, and then a cooling roll is passed to complete the heat treatment. At this time, a smoother surface can be obtained by making the surface of the roll a mirror surface, and a mat-like surface can be obtained by giving a shape to the surface of the roll.

  The heating means for the ink jet recording material in the present invention is not particularly limited. Specifically, it applies hot air directly, irons it, passes it between heating rolls such as a laminator often used for post-processing of large format printer output images, and attaches it to a heated mirror drum used for drying pictures etc. The method of using a type dryer etc. is mentioned. Among these methods, a method using a laminator that can be heated and densified by passing between pressurized rolls is more preferable because large-sized heat treatment can be performed uniformly, and the pressure applied by the pressure roll is more preferable. The surface pressure is preferably 0.1 to 2.5 MPa. If the surface pressure is less than 0.1 MPa, it is not preferable because the surface gloss is poor and the ozone resistance is poor due to problems such as uneven pressure application and uneven heat transfer. . In addition, when a pressure exceeding 2.5 MPa is applied, when the thermoplastic organic polymer fine particles are heated and densified, the pressure is excessively applied to roughen the surface and lower the glossiness. It is not preferable because it is deformed by pressure.

  The ink used in the ink jet recording material of the present invention and the ink jet image forming method using the same can be applied not only to the ink used in a normal ink jet printer but also to the toner ink used in a copying apparatus. As long as the fixing process uses heat / pressure treatment, it is not limited to a specific printing method or a specific copying method.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples indicate parts by mass and mass% unless otherwise specified.

<Support A>
320 parts of hardwood bleached kraft pulp beaten to 320 ml with double disc refiner, csf and 75 parts of hardwood bleached kraft pulp beaten to 430 ml, csf with double disc refiner Then, 0.1 part of alkyl ketene dimer sizing agent and 7 parts of heavy calcium carbonate filler were added to water to prepare a paper slurry. From the stock slurry, a paper web is formed with a long paper machine, squeezed with a press, dried in a multi-cylinder dryer drying process, and a 5% aqueous solution of oxidized starch is size-pressed in the middle of drying (the adhesion amount is Ink-jet recording with a basis weight of 120 g / m ² , dried on a double-sided dry solid content of 3.5 g / m ² ) and finally dried to a base paper moisture of 8% with absolutely dry moisture. A support A for the material was produced.

<Support B>
After performing corona discharge treatment on both surfaces of the support A in advance, melt extrusion coating was performed using a melt extrusion die so that low density polyethylene (density 0.924) was applied at a coating amount of 12 g / m ² . Thereafter, an anchor coat layer (composition: 95 parts of gelatin in the dry solid part and 5 parts of chromium alum) was provided on the surface of the low density polyethylene at a dry coating amount of 2.0 g / m ² to produce a support B.

<Support C>
A commercially available white PET film (Diafoil W, manufactured by Diafoil Hoechst Co., Ltd., 125 μm) was used as the support C as it was.

  Next, the ink jet recording layer coating solution will be described. The following “parts” are all solid conversion parts. The mass ratio of inorganic ultrafine particles / thermoplastic organic polymer fine particles is simply referred to as “mass ratio”.

The following inkjet recording layer coating solution was applied to the surface of the support to form an inkjet recording layer.
Side A: An ink jet recording layer coating solution was formed as follows.
<Inkjet recording layer coating solution 1>
Inkjet recording layer coating solution 1 was prepared according to the following formulation. The thermoplastic organic polymer fine particles and inorganic ultrafine particles supplied as powder are preliminarily dispersed using a homogenizer in advance, and then stirred and mixed in a lab mixer while sequentially adding each component. It was set as the coating liquid.
Inorganic ultrafine particles 100 parts Thermoplastic organic polymer fine particles 20 parts Polyvinyl alcohol 15 parts Sumire resin 5004 (waterproofing agent) 0.5 parts Solid content concentration 30%
In addition, Arakawa Chemical Industries Co., Ltd. (trade name “Mist Pearl C-150”, average particle size: 52 nm, two carbon-carbon double bonds and a quaternary ammonium base as thermoplastic organic polymer fine particles. Polystyrene fine particles cross-linked) and fumed alumina particles manufactured by CABOT as fine inorganic particles are pulverized and dispersed with a sand grinder, and then further pulverized and dispersed using a microfluidizer. Alumina (θ-alumina, δ-alumina, γ-alumina mixed mass ratio is about 3: 1: 1) particles were used. PVA235 manufactured by Kuraray Co., Ltd. was used as polyvinyl alcohol. The mass ratio was 5.

<Inkjet recording layer coating solution 2>
Thermoplastic organic polymer fine particles manufactured by Arakawa Chemical Industries, Ltd. (trade name “Mist Pearl C-100”, average particle size: 72 nm, crosslinked by an emulsifier having two carbon-carbon double bonds and a quaternary ammonium base. Inkjet recording layer coating solution 1 except that commercially available colloidal alumina hydrate having an average secondary particle diameter of 180 nm (Cataloid AS-3: manufactured by Catalyst Kasei Co., Ltd.) was used as the inorganic ultrafine particles. The same formulation was used. The mass ratio was 5.

<Inkjet recording layer coating solution 3>
The inorganic ultrafine particles were prepared by the same formulation as the inkjet recording layer coating solution 2 except that Aerosil 200 (average secondary particle diameter 150 nm) manufactured by Nippon Aerosil Co., Ltd., which is vapor phase method silica, was used. The mass ratio was 5.

<Inkjet recording layer coating solution 4>
The ink jet recording layer coating solution 1 was prepared in the same manner as the ink jet recording layer coating solution 2 except that 4 parts of thermoplastic organic polymer fine particles were used. The mass ratio was 25.

<Inkjet recording layer coating solution 5>
Prepared according to the same formulation as Inkjet recording layer coating solution 2 except that 36 parts of commercially available colloidal alumina hydrate (Cataloid AS-3: produced by Catalyst Kasei Co., Ltd.) having an average particle size of 180 nm was used as the ultrafine inorganic particles. did. The mass ratio was 1.8.

<Inkjet recording layer coating solution 6>
Inkjet recording layer coating solution 2 except that the inorganic ultrafine particles were changed to commercially available alumina particles (manufactured by Sumitomo Chemical Co., Ltd., trade name: AKP-G015, γ-alumina, average secondary particle diameter of 3 to 5 μm). The same formulation was used. The mass ratio was 5.

<Inkjet recording layer coating solution 7>
It was prepared according to the same formulation as the inkjet recording layer coating solution 2 except that an acrylic emulsion (trade name: AE940, manufactured by JSR Corporation) having an average particle size of 0.48 μm was used as the thermoplastic organic polymer fine particles. The mass ratio was 5.

<Inkjet recording layer coating solution 8>
In the formulation of the ink jet recording layer coating liquid 1, it was prepared in the same manner as the ink jet recording layer coating liquid 2 except that the inorganic ultrafine particles were not added, and a coating liquid containing no inorganic ultrafine particles was obtained.

<Inkjet recording layer coating solution 9>
The inkjet recording layer coating liquid 9 containing no thermoplastic organic polymer fine particles was prepared according to the following formulation. While adding each component sequentially, stirring and mixing were performed with a lab mixer to obtain a coating solution. The inorganic ultrafine particles were preliminarily dispersed using a homogenizer in advance.
Inorganic ultrafine particles 100 parts Polyvinyl alcohol 20 parts Sumire resin 5004 (waterproofing agent) 2 parts Solid content concentration 18%
The inorganic ultrafine particles were the same as those used in the inkjet recording layer coating solution 2, and the polyvinyl alcohol was PVA235 manufactured by Kuraray.

Side B: An inkjet recording layer coating solution was formed as follows.
<Inkjet recording layer coating solution 10>
The inkjet recording layer coating solution 10 was prepared according to the following formulation. The thermoplastic organic polymer fine particles and inorganic ultrafine particles supplied as powder are preliminarily dispersed using a homogenizer in advance, and then stirred and mixed in a lab mixer while sequentially adding each component. It was set as the coating liquid.
Inorganic ultrafine particles 100 parts Thermoplastic organic polymer fine particles 20 parts Polyvinyl alcohol 15 parts Sumire resin 5004 (waterproofing agent) 0.5 parts Solid content concentration 30%
In addition, ethylene-vinyl acetate copolymer (particle size: 7 μm: manufactured by Chemipearl V-200, Mitsui Chemicals) is used as the thermoplastic organic polymer fine particles, and fumed alumina particles manufactured by CABOT are pulverized and dispersed with a sand grinder as the inorganic ultrafine particles. After that, pulverization and dispersion were further repeated using a microfluidizer, and particles with an average secondary particle diameter of 300 nm were fumed alumina (the mixing mass ratio of θ-alumina, δ-alumina, and γ-alumina was about 3: 1: 1). Was used. PVA235 manufactured by Kuraray Co., Ltd. was used as polyvinyl alcohol. The mass ratio was 5.

<Inkjet recording layer coating solution 11>
As thermoplastic organic polymer fine particles, polypropylene wax (particle size: 1 μm: Chemipearl WP-100, manufactured by Mitsui Chemicals), as inorganic ultrafine particles, commercially available colloidal alumina hydrate (Cataloid AS-) having an average secondary particle size of 180 nm 3: prepared by the same method as the ink jet recording layer coating solution 10 except that the catalyst) was used. The mass ratio was 5.

<Inkjet recording layer coating solution 12>
The inorganic ultrafine particles were prepared according to the same formulation as the inkjet recording layer coating solution 11 except that Aerosil 200 (average secondary particle diameter 150 nm) manufactured by Nippon Aerosil Co., Ltd., which is vapor phase method silica, was used. The mass ratio was 5.

<Inkjet recording layer coating solution 13>
The thermoplastic organic polymer fine particles are changed to styrene / acrylic copolymer (particle size: 1 μm: Ropaque HP-91 manufactured by Rohm & Haas Co.) in the ink jet recording layer coating liquid 10, and the inorganic secondary fine particles are average secondary. It was prepared by the same formulation as the inkjet recording layer coating solution 11 except that 36 parts of a commercially available colloidal alumina hydrate having a particle size of 180 nm (Cataloid AS-3: produced by Catalyst Kasei Co., Ltd.) was used. The mass ratio was 1.8.

<Inkjet recording layer coating solution 14>
The same formulation as the inkjet recording layer coating solution 11 except that 4 parts of an ionomer resin (particle size: 0.5 μm: manufactured by Chemipearl S-300, Mitsui Chemicals) was used in the inkjet recording layer coating solution 10. It was prepared by. The mass ratio was 25.

<Inkjet recording layer coating solution 15>
Similar to the ink jet recording layer coating solution 11 except that instead of the inorganic ultrafine particles, commercially available alumina particles (manufactured by Sumitomo Chemical Co., Ltd., trade name: AKP-G015, γ-alumina, average secondary particle diameter of 3 to 5 μm) were used. It was prepared according to the following formula. The mass ratio was 5.

<Inkjet recording layer coating solution 16>
It was prepared according to the same formulation as the inkjet recording layer coating solution 11 except that NIPSEAL E200 (amorphous silica, particle diameter 3.4 μm) manufactured by Nippon Silica Industry Co., Ltd. was used instead of the inorganic ultrafine particles. The mass ratio was 5.

<Inkjet recording layer coating solution 17>
In the formulation of the ink jet recording layer coating solution 10, a coating solution containing no inorganic ultrafine particles was prepared in the same manner as the ink jet recording layer coating solution 11 except that the inorganic ultrafine particles were not added.

<Inkjet recording layer coating solution 18>
The inkjet recording layer coating solution 18 not containing thermoplastic organic polymer fine particles was prepared according to the following formulation. While adding each component sequentially, stirring and mixing were performed with a lab mixer to obtain a coating solution. The inorganic ultrafine particles were preliminarily dispersed using a homogenizer in advance.
Inorganic ultrafine particles 100 parts Polyvinyl alcohol 20 parts Sumire resin 5004 (waterproofing agent) 2 parts Solid content concentration 18%
The inorganic ultrafine particles were the same as those used in the inkjet recording layer coating solution 11, and the polyvinyl alcohol was PVA235 manufactured by Kuraray.

On one side (A side) of the support A, the inkjet recording layer coating solution 1 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The ink jet recording layer coating liquid 10 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. to prepare the ink jet recording material of Example 1.

On one side (A side) of the support B, the inkjet recording layer coating solution 2 was applied with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. The ink jet recording layer coating liquid 11 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. to prepare the ink jet recording material of Example 2.

On one side (A side) of the support C, the inkjet recording layer coating solution 3 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The inkjet recording layer coating liquid 12 was applied onto the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. to prepare an inkjet recording material of Example 3.

On one side (A side) of the support B, the inkjet recording layer coating solution 4 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The inkjet recording layer coating liquid 13 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. to prepare an inkjet recording material of Example 4.

On one side (A side) of the support B, the inkjet recording layer coating solution 5 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The inkjet recording layer coating solution 14 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. to prepare an inkjet recording material of Example 5.

(Comparative Example 1)
On one side (A side) of the support B, the inkjet recording layer coating solution 6 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The inkjet recording layer coating liquid 15 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² , and dried at 80 ° C. to prepare an inkjet recording material of Comparative Example 1.

(Comparative Example 2)
On one side (A side) of the support B, the inkjet recording layer coating solution 7 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The inkjet recording layer coating liquid 16 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² , and dried at 80 ° C. to prepare an inkjet recording material of Comparative Example 2.

(Comparative Example 3)
On one side (A side) of the support B, the inkjet recording layer coating solution 8 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The ink jet recording layer coating liquid 17 was applied to the surface (B surface) with a coating rod so that the dry coating amount was 25 g / m ² , and dried at 80 ° C. to prepare an ink jet recording material of Comparative Example 3.

(Comparative Example 4)
On one side (A side) of the support B, the inkjet recording layer coating solution 9 was applied with a coating rod to a dry coating amount of 15 g / m ² , dried at 120 ° C., and then coated with the inkjet recording layer. After coating the working liquid 18 with a coating rod so that the dry coating amount is 10 g / m ² and drying at 120 ° C., two layers are formed on the other side (B side) of the support under the same conditions as the A side. Was applied to prepare an inkjet recording material of Comparative Example 4.

(Comparative Example 5)
On one side (A side) of the support B, the inkjet recording layer coating solution 1 is applied with a coating rod so that the dry coating amount is 25 g / m ² , dried at 80 ° C., and then the other side of the support. The same ink jet recording layer coating liquid 1 as that of the A side was coated on the side (B side) with a coating rod so that the dry coating amount was 25 g / m ² and dried at 80 ° C. Was made.

(Comparative Example 6)
On one side (A side) of the support B, the inkjet recording layer coating solution 9 was applied with a coating rod to a dry coating amount of 15 g / m ² , dried at 120 ° C., and then coated with the inkjet recording layer. After coating the working liquid 8 with a coating rod so that the dry coating amount becomes 10 g / m ² and drying at 80 ° C., the other side (B side) of the support is also subjected to 2 under the same conditions as the A side. The ink-jet recording material of Comparative Example 6 was produced by applying the layer.

<Preparation of inkjet recording>
Using a color ink jet printer (PM-770C) manufactured by Epson on the A side of the ink jet recording material obtained as described above, solid printing of four primary colors and recording of a high-definition photographic image were performed, and then character information was recorded on the B side. Recorded.

<Filming of thermoplastic organic polymer fine particles>
After double-sided printing of the inkjet recording obtained as described above, a large laminator (M-36 manufactured by Fuji Film Co., Ltd.) is used, and the heated printed material is passed through two heating rollers while being sandwiched between non-fused polyester films. The heat densification process was performed by. The surface pressure during the heat densification treatment was 2.0 MPa, and the heating temperature was 160 ° C.

  After the two-sided recording of photographic images and character information was performed on the ink-jet recording material prepared in Example 2 using the Epson color ink-jet printer (PM-770C), the surface pressure during heat densification was 0.05 MPa. An inkjet recorded matter of Example 6 was prepared by using the above-described method for forming a film of thermoplastic organic polymer fine particles, except that the above-described method was changed.

  After the two-sided recording of photographic images and character information was performed on the ink-jet recording material prepared in Example 2 using the Epson color ink-jet printer (PM-770C), the surface pressure during heat densification was 3.0 MPa. An inkjet recorded matter of Example 7 was prepared using the above-described method for forming a film of thermoplastic organic polymer fine particles except that the method was changed to the above.

<Evaluation>
The ink jet recording materials of Examples 1 to 7 and Comparative Examples 1 to 6 were evaluated in five stages as described below. Table 1 summarizes the evaluation results for the A side with respect to ink absorption speed, image quality, gloss, and ozone resistance.

<Ink absorption speed>
For images recorded using an Epson color ink jet printer (PM-770C), the ink absorption speed is measured after the recording is completed, before the thermal melt coating is formed, by rubbing the printed part lightly with a fingertip to eliminate the stain, Evaluation was made according to the following criteria. The pass is 4 or more.
5: Ink absorption speed is less than 10 seconds 4: Ink absorption speed is from 10 seconds to less than 30 seconds 3: Ink absorption speed is from 30 seconds to less than 60 seconds 2: Ink absorption speed is from 1 minute to 5 minutes Is less than 1: ink absorption speed is 5 minutes or more

<Image quality>
The image quality of the recorded image after coating the thermoplastic organic polymer fine particles was visually evaluated in the following five stages. The pass is 4 or more.
5: The image looks completely clear and the image is not blurred at all 4: The image looks clear, a slight blur of the image is observed, but there is no practical problem 3: The image looks dull as if slightly blurred 2: Blurring increases and whitish saturation decreases, image blur is inferior 1: Image is very whitish and saturation is very low, image blur is very inferior

<Glossy>
The glossiness of the white paper after the thermoplastic organic polymer fine particles were melt-coated was evaluated in the following five levels. The pass is 4 or more.
5: very high gloss 4: high gloss 3: slightly inferior gloss 2: inferior gloss 1: no gloss

<Ozone resistance>
After double-sided solid printing of each ink-jet recording material, after coating the thermoplastic organic polymer fine particles, the ink-jet recording material is placed in a glass container with an ozone inlet and an outlet, and is placed in an ozonizer OS-1 manufactured by Mitsubishi Electric. Generated ozone was continuously introduced for 15 minutes. The ozone concentration at this time was about 80 ppm. The color difference of the magenta ink color before and after the ozone treatment of these ink jet recording materials was measured. The color difference can be defined by the following equation 1 based on the result of measuring the color of the sample before and after light irradiation according to L ^* a ^* b ^* (CIE 1976). A larger color difference indicates that color degradation has occurred. If the color difference is less than 3.0, there is no significant difference in color visually.

Here, ΔE is a color difference, ΔL ^* and Δa ^* and Δb ^* are differences between L ^* and a ^* and b ^* before and after light irradiation, respectively.

<Curl properties>
The inkjet recording material used in Examples 1 to 5 and Comparative Examples 1 to 6 is an A4 size recording material, and the same image over the entire printable area is formed on the A side with a resolution of 720 dpi on the B side. Were each printed at a resolution of 360 dpi, cut into 10 cm squares, and placed on a flat desk at 20 ° C. and a relative humidity of 65% to measure curl. The curl is expressed by the average value of the lifting heights at the four corners. When the curl average value is less than 3 mm, the curl is excellent, and the curl is as good as 3 mm to 7 mm. Therefore, it was determined as poor curl. In Examples 6 to 7, after the printing, the thermoplastic organic polymer fine particles were coated on the film under the same conditions as in Examples 6 to 7, and then the curl average value was measured under the above conditions.

  From Table 1, in the ink jet recording material provided with an ink jet recording layer containing a mixture of inorganic ultrafine particles and thermoplastic organic polymer fine particles on both sides of the support as in the examples of the present invention, the average secondary of the inorganic ultrafine particles is shown. In an ink jet recording material having a particle size of 300 nm or less and an average particle size of the thermoplastic organic polymer fine particles being different between the front and back, ink absorbency, image quality, glossiness, ozone resistance, and after printing The curl characteristics were good. In this case, by optimizing the mass ratio of the thermoplastic organic polymer fine particles and the inorganic ultrafine particles, it becomes possible to obtain more excellent images, high glossiness and ozone resistance. If the amount of the thermoplastic organic polymer fine particles added to the inorganic ultrafine particles is too large, the ink absorbability is inferior, and if it is too small, the glossiness and ozone resistance are deteriorated. This is probably because the voids in the ink jet recording layer are not filled with the coating of the thermoplastic organic polymer fine particles.

  On the other hand, Comparative Example 1 is a case where the inkjet recording layer contains alumina particles having a large particle size, and is inferior in image quality and gloss. Comparative Example 2 is a case where the inkjet recording layer contains thermoplastic organic polymer fine particles having a large particle size and is inferior in image quality. Comparative Example 3 is a case where the inkjet recording layer contains only thermoplastic organic polymer fine particles and no inorganic ultrafine particles, and is inferior in ink absorption speed and image quality. Comparative Example 4 is a case where the inkjet recording layer does not contain thermoplastic organic polymer fine particles and is inferior in ozone resistance. Comparative Example 5 is a case where the same ink jet recording layer coating solution is provided on both sides of the support, and the curl characteristics are inferior when the ink adhesion amount is different between the front and back surfaces. Comparative Example 6 is a case where an inorganic ultrafine particle layer and a thermoplastic organic polymer fine particle layer are laminated on a support, and the ink absorption is hindered by the thermoplastic organic polymer fine particle layer, resulting in poor ink absorbability and image quality. The curl characteristics are also inferior.

Claims (4)

  In an inkjet recording material provided with an inkjet recording layer containing a mixture of inorganic ultrafine particles and thermoplastic organic polymer fine particles on both sides of a support, the average secondary particle diameter of the inorganic ultrafine particles is 300 nm or less, and the support The average particle size of the thermoplastic organic polymer fine particles on one side is 300 nm or less, and the average particle size of the thermoplastic organic polymer fine particles on the other side of the support is 0.1 μm or more and 10 μm or less. Inkjet recording material.   2. The ink jet recording material according to claim 1, wherein the mass ratio of the inorganic ultrafine particles / thermoplastic organic polymer fine particles in the ink jet recording layer is 2 or more and 20 or less.   An image forming method using the inkjet recording material according to claim 1, wherein the thermoplastic organic polymer fine particles are heated by printing the inkjet recording material and then heating the inkjet recording material. A method for forming an ink jet image, comprising heating and densifying the material.   4. The ink jet image forming method according to claim 3, wherein the heat densification method is a heat densification method by passing between heated and pressurized rolls, and the pressure applied to the ink jet recording material by the pressure rolls. Has a surface pressure of 0.1 to 2.5 MPa.