JP2007125781A - Inkjet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording material which is excellent in transparency, ink absorbability, an adhesive strength between an ink receiving layer and a transparent substrate, curling resistance and set-off resistance. <P>SOLUTION: The inkjet recording material is provided with the ink receiving layer (A) comprising at least two layers comprising a vapor phase-processed silica with a mean secondary particle diameter of ≤300 nm and a binder on one face of the transparent substrate. The mass ratio of the vapor phase-processed silica and the binder is 75:25-50:50 in the ink receiving layer (A1) being nearest to the transparent substrate among the ink receiving layers (A), and 95:5-75:25 in the farthest ink receiving layer (A2), and a back coating layer comprising a colloidal silica and a binder is provided on a face on the opposite side of the face provided with the ink receiving layer (A) in a range of the amount of coating of a solid content of 3-18 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording material, and more particularly to an ink jet recording material excellent in transparency, ink absorbability, adhesion strength between an ink receiving layer and a transmissive support, curl resistance, and anti-back-through characteristics, and particularly an ink jet recording system. The present invention relates to an ink jet recording material suitable for use as a printing plate precursor film produced by the above method.

  As a recording material used in the ink jet recording system, a swellable ink receiving layer mainly composed of a hydrophilic polymer or a pigment such as amorphous silica is mainly composed on a support made of ordinary paper or film. A recording material provided with a porous ink receiving layer is known.

  In the case of providing a porous ink-receiving layer, in recent years, ultrafine inorganic particles as a pigment, for example, inorganic ultrafine particles such as pulverized and dispersed gas phase method silica or wet method silica as a pigment component of the ink receiving layer. It has been proposed to use. For example, JP-A-3-56552, JP-A-10-119423, JP-A-2000-2111235, and JP-A-2000-309157 disclose examples of using vapor phase silica. JP-A-9-286165, JP-A-10 No. 181190 discloses a use example of pulverized sedimentation silica, and Japanese Patent Application Laid-Open No. 2001-277712 discloses a use example of crushed gel method silica. JP-A-62-174183, JP-A-2-276670, JP-A-5-32037, JP-A-6-199034 and the like disclose recording materials using alumina or alumina hydrate.

  As the use of inkjet recording materials expands, it has been proposed to be used for applications such as printing plate under-films, overhead projectors, and medical image output such as chest X-ray and ultrasonic diagnosis. In such an ink jet recording material, a transparent plastic film is often used as a support. In general, when a porous ink-receiving layer is provided on a plastic film support, the adhesive strength between the support and the ink-receiving layer tends to be inferior compared to the case where paper is used as the support. When the ink jet recording material is finished in the form of a roll or when it is handled, the coating layer may be peeled off from the support. In particular, when handling large-format recording materials, such as for printing plate films, the coating layer often peels off when the recording material is folded or bent during handling, which has a significant adverse effect on the recorded image. In some cases, the film could not withstand use as a printing film. When a swellable ink-receiving layer mainly composed of a hydrophilic polymer is provided, such a problem is unlikely to occur, but when a porous ink-receiving layer mainly composed of a pigment that requires quick drying is provided. This is a big problem in practical use.

  For example, JP-A-7-276789, JP-A-8-72392, JP-A-2001-113817, JP-A-2002-240417, JP-A-2003-240417 are examples of inkjet recording materials using a transparent support as a support. No. 276313 is disclosed.

  In order to improve the adhesive strength between a support made of a plastic film and a coating layer, a primer layer mainly composed of a natural resin or a synthetic resin is provided on the support. In order to improve the adhesive strength, Japanese Patent Application Laid-Open No. 2004-25836 (Patent Document 1) discloses an additional method comprising a binder and a cationically modified silica between a support and an ink receiving layer. It has been proposed to provide an adhesion promoting layer. JP-A-9-202039 (Patent Document 2) proposes to provide a primer treatment layer mainly composed of alumina sol between an ink fixing layer mainly composed of a water-soluble polymer and a support. ing. JP-A-9-188065 (Patent Document 3) improves wettability by providing an undercoat layer containing fine particles of titanium oxide and / or zinc oxide on a translucent substrate, It has been proposed that the adhesion to the ink receiving layer formed in the upper layer is improved.

  However, it was not possible to satisfy all of transparency, ink absorbability, adhesive strength between the support and the ink receiving layer, and curl resistance necessary for the recording material, which are important characteristics as a transparent recording material. When only a porous ink-receiving layer having excellent ink absorbability is applied, adhesion strength to the support cannot be obtained, and adhesion to the lower layer of the ink-receiving layer having excellent ink absorbability is not possible. Even when a coating layer for improving the strength was provided, there was a problem that the recorded image was cracked after the ink was dried after ink jet recording. Further, the curl of the recording material is large, and there is a problem in the transportability in the ink jet printer.

  If the ink-receiving surface of the ink-jet recording material has a large curl, troubles such as rubbing the printer head against the ink-jet recording material occur when printing with an ink-jet printer, making it impossible to print normally. Therefore, in order to improve the curl resistance, a backing layer is provided on the surface opposite to the surface on which the ink receiving layer is provided. However, even if the image is sufficiently dried after image printing, if the printed matter is stacked, water or solvent derived from the ink remaining in the image area where the amount of applied ink is large is transferred to the back surface, and the transferred portion becomes cloudy. was there. When a transparent support is used as the support, the transfer portion is visible even from the ink receiving surface side, and it is difficult to recognize the image normally. In addition, blocking may occur due to transfer of water or solvent.

  Japanese Laid-Open Patent Publication No. 2002-240417 (Patent Document 4) proposes a light-transmitting ink jet recording material in which a printed image does not show through by setting the composition of the backing layer and the porosity within a specific range. However, it has not been possible to provide an ink jet recording material that has all of transparency, ink absorptivity, adhesion strength between the ink receiving layer and the transparent support, curl resistance, and anti-show-through properties.

Further, when used for a printing plate precursor film, it is preferable to have a vacuum drawing ability. The image formed on the undercoat film is baked onto the printing plate by contact exposure, but in order to form a sharp image, it is necessary to ensure that the undercoat film and the printing plate are in close contact in the exposure process. . If the adhesion is poor, the light wraps around where light should be shielded and the outline of the image blurs, resulting in a reduction in image quality. Therefore, the adhesion is improved by the evacuation process, but if the smoothness of the underlay film is too high, the underlay film and the printing plate may be misaligned, or the underprint film and the printing plate There was a problem that the air in the gap was not discharged uniformly, and a long time was required for evacuation. Therefore, a recording material that can be evacuated efficiently is suitable for use as a printing plate precursor film.
JP 2004-25836 A JP-A-9-202039 Japanese Patent Laid-Open No. 9-188065 Japanese Patent Laid-Open No. 2002-240417

  An object of the present invention is excellent in transparency, ink absorptivity, adhesion strength between an ink receiving layer and a transparent support, curl resistance, and show-through resistance in an inkjet recording material, and is particularly produced by an inkjet recording method. An object of the present invention is to provide an ink jet recording material suitable for use as a printing plate precursor film.

The above object of the present invention has been achieved by the following invention.
(1) In an ink jet recording material in which an ink receiving layer (A) comprising at least two layers containing vapor phase silica having an average secondary particle diameter of 300 nm or less and a binder is provided on one side of a transparent support. The mass ratio of the vapor phase silica and the binder contained in the ink receiving layer (A1) closest to the transparent support in the ink receiving layer (A) is 75:25 to 50:50, The mass ratio of the vapor phase silica contained in the ink receiving layer (A2) farthest from the transparent support in the ink receiving layer (A) to the binder is 95: 5 to 75:25, and On the surface opposite to the surface on which the ink receiving layer (A) is provided, a backing layer containing colloidal silica and a binder is provided in a range of 3 to 18 g / m ^{2 in} terms of solid content. An ink jet recording material characterized by comprising:
(2) The ink jet recording material according to claim 1, wherein the average primary particle diameter of the vapor phase silica contained in the ink receiving layer (A) is 20 nm or less.
(3) The ink jet recording material according to claim 1 or 2, wherein the binder contained in the ink receiving layer (A1) is polyvinyl alcohol.
(4) In the ink receiving layer (A), the ink receiving layer (A2) farthest from the transparent support and / or the backing layer contains a matting agent having an average secondary particle diameter of 3 to 20 μm. The ink jet recording material according to claim 1, 2 or 3.

  The ink jet recording material of the present invention is excellent in transparency, ink absorptivity, adhesive strength between the ink receiving layer and the support, curl resistance, and anti-back-through, and is particularly under a printing plate prepared by an ink jet recording method. It is an inkjet recording material suitable for film applications.

Hereinafter, the present invention will be described in detail.
The ink receiving layer (A) of the present invention contains gas phase method silica having an average secondary particle diameter of 300 nm or less and a binder in order to obtain high transparency and ink absorbability, and is the ink closest to the transparent support. It consists of at least two layers, a receiving layer (A1) and the farthest ink receiving layer (A2). In order to obtain the adhesive strength between the transparent support and the ink receiving layer, the mass ratio of the vapor phase silica contained in the ink receiving layer (A1) and the binder is 75:25 to 50:50, and an excellent ink In order to obtain absorption, the mass ratio of the vapor phase silica contained in the ink receiving layer (A2) to the binder is 95: 5 to 75:25.

  The ink receiving layer (A) of the present invention can have both the adhesive strength between the transparent support and the ink receiving layer and the ink absorptivity by forming a multilayer structure as described above. Adhesive strength cannot be obtained with a single-layer configuration comprising only the ink-receiving layer (A2) with emphasis on ink absorbency, and ink-absorbing properties can be achieved with a single-layer configuration comprising only the ink-receiving layer (A1) with emphasis on adhesive strength. Can't get.

  Vapor phase silica used in the present invention is amorphous synthetic silica, and amorphous synthetic silica can be roughly classified into wet method silica and others in addition to the above-mentioned vapor phase silica depending on the production method. Vapor phase silica is also called a dry method as opposed to a wet method, 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 silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Co., Ltd.

  The characteristic of the vapor phase method silica is that the primary particles are connected in a network structure or chain shape and are present in a secondary aggregate state to form appropriate voids. In the present invention, gas phase method silica having an average secondary particle diameter of 300 nm or less is used in order to enhance transparency. Vapor phase silica fine particles dispersed and pulverized in a dispersion medium such as water with an ultrasonic wave, a high-pressure homogenizer, a counter collision type jet pulverizer, or the like until the particle size is preferably 250 nm or less, more preferably 200 nm or less are formed in the ink receiving layer (A ).

The average primary particle size of the vapor-phase process silica used in the present invention is preferably 30 nm or less, and more preferably 20 nm or less in order to obtain high transparency and to easily obtain a small average secondary particle size by dispersion and pulverization. It is. And in order to obtain high absorbency, it is preferable to use the thing whose specific surface area by BET method is 90-400 m < ² > / g. The BET method is a method for measuring the surface area of a powder by a gas phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from an adsorption isotherm. Usually, nitrogen gas is often used as the adsorbed gas, and the most frequently used method is to measure the amount of adsorption from the change in pressure or volume of the gas to be adsorbed. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller formula, called the BET formula, which is widely used for determining the surface area. The adsorption amount is obtained based on the BET equation, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface.

  In addition, the average primary and secondary particle diameter as used in the field of this invention is based on the well-known method observed with an electron microscope (SEM and TEM). The average particle diameter of the primary particles can be obtained as the particle diameter by measuring the diameter of a circle equal to the projected area of each of 100 particles existing within a certain area by observing the dispersed particles with an electron microscope. The average particle diameter of the secondary particles can be determined by observing particles dispersed with a gentle shear force with an electron microscope.

  In the present invention, the vapor phase silica contained in the ink receiving layer (A2) farthest from the transparent support in the ink receiving layer (A) is intended to improve the fixability of an anionic ink. It is preferably used in a cationized state. Cationized gas phase method silica can be obtained by dispersing gas phase method silica in a dispersion medium mainly composed of water in the presence of a cationic compound. At this time, it is preferable to disperse in a state in which a hydrophilic binder such as polyvinyl alcohol and a crosslinking agent (hardener) such as boric acid are not included.

  In the present invention, the vapor-phase process silica contained in the ink receiving layer (A1) closest to the transparent support among the ink receiving layers (A) does not need to be cationized. Cationized vapor phase silica preferably used for the receiving layer (A2) may be used in common.

  Examples of the cationized vapor-phase silica include those described in JP-A No. 11-321079, JP-A No. 2000-239536, JP-A No. 2001-19421, JP-A No. 2001-80204, JP-A No. 2001-207078, and the like. A method of dispersing vapor phase silica in the presence of a compound is described, and any method can be employed in the present invention.

  A cationic polymer or a water-soluble metal compound can be used as the cationic compound used for dispersion or pulverization of the vapor phase silica. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-155088. JP, 60-11389, JP 60-49990, JP 60-83882, JP 60-109894, JP 62-198493, JP 63-49478, 1 described in JP-A-63-115780, JP-A-63-280681, JP-A-1-40371, JP-A-6-234268, JP-A-7-125411, JP-A-10-193976, etc. A polymer having a tertiary amino group or a quaternary ammonium base is preferably used. In particular, diallylamine derivatives are preferably used as the cationic polymer. The molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000. A molecular weight greater than 100,000 is not preferred because the dispersion becomes too viscous.

  Examples of the water-soluble metal compound include water-soluble polyvalent metal salts, and among them, a compound made of aluminum or a group 4A metal (for example, zirconium or titanium) in the periodic table is preferable. Particularly preferred is a water-soluble aluminum compound. As a water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like are known. Furthermore, a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer is known and preferably used.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2, or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ _{, [Al 13 (OH) 34} ] 5+, with _{[Al 21 (OH) 60]} 3+, basic water-soluble that contain polynuclear condensed ions of a polymer stable at of polyaluminum hydroxide as an equal is there.

[Al ₂ (OH) _n Cl _6-n ] _m General formula 1
[Al (OH) ₃ ] _n AlCl ₃ general formula 2
Al _n (OH) _m Cl _(3n-m) 0 <m <3n General formula 3

  These are water treatment agents from Taki Chemical Co., Ltd. under the name of polyaluminum chloride (PAC), from Asada Chemical Co., Ltd. under the name of polyaluminum hydroxide (Paho), and from Riken Green Co., Ltd. It is marketed under the name of Purachem WT and from other manufacturers for the same purpose, and various grades can be easily obtained.

  The water-soluble compound containing a Group 4A element of the periodic table that can be used in the present invention is more preferably a water-soluble compound containing titanium or zirconium. Examples of the water-soluble compound containing titanium include titanium chloride and titanium sulfate. Water-soluble compounds containing zirconium include zirconium acetate, zirconium chloride, zirconium oxychloride, hydroxy zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium lactate, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate. And zirconium fluoride compounds. In the present invention, the term “water-soluble” means that 1% by mass or more dissolves in water at room temperature and normal pressure.

  In the ink receiving layer (A2) of the present invention, a binder is used in order to maintain the properties as a film and to obtain higher ink permeability. Although it is preferable to use a hydrophilic binder as the binder, it is important that the hydrophilic binder does not swell during the initial permeation of the ink and block the gap. A low hydrophilic binder is particularly preferably used. Polyvinyl alcohol compounds, polyethylene glycol compounds, starches, dextrin, carboxymethyl cellulose, and their derivatives are used. Particularly preferred in the present invention is fully or partially saponified polyvinyl alcohol or cation-modified polyvinyl alcohol.

  Particularly preferred among the polyvinyl alcohols are those having a degree of saponification of 80% or more or those completely saponified. Polyvinyl alcohol having an average degree of polymerization of 500 to 5000 is preferred. The cation-modified polyvinyl alcohol has a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain of the polyvinyl alcohol as described in, for example, JP-A-61-10383. Polyvinyl alcohol.

  A binder is also used in the ink receiving layer (A1) of the present invention in order to obtain adhesion strength and film strength with the transparent support. As a binder used in the ink receiving layer (A1), polymers such as acrylonitrile-butadiene copolymer, acrylate polymer, vinyl acetate polymer, styrene-butadiene copolymer, or derivatives thereof, polyvinyl alcohol Compounds, polyethylene glycol compounds, starches, dextrin, carboxymethylcellulose and the like and derivatives thereof can be used. In the present invention, preferred is polyvinyl alcohol, and particularly preferred is a partially saponified polyvinyl alcohol having an average polymerization degree of 500 to 5000 and a saponification degree of 80% or more.

  In the ink receiving layer (A) of the present invention, it is preferable to use a crosslinking agent (hardener) together with the binder. Specific examples of the crosslinking agent include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea), 2-hydroxy-4,6-dichloro-1, 3,5-triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, a compound having a reactive olefin as described in US Pat. No. 3,635,718, N-methylol compounds as described in Japanese Patent No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. Nos. 3,017,280 and 2,983,611 described Aziridine compounds such as US Pat. No. 3,100,704, carbodiimide compounds, US Epoxy compounds such as those described in allowed 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, zirconium sulfate, boric acid, borate, inorganic cross-linking agents such as borax, etc. These can be used alone or in combination of two or more.

  In the ink receiving layer (A) of the present invention, when polyvinyl alcohol preferable as a binder is used, it is preferable to use boric acid, borax or borate as a crosslinking agent. Examples of boric acid include orthoboric acid, metaboric acid, and hypoboric acid. Examples of the boric acid salt include sodium salt, potassium salt, and ammonium salt. The content of the crosslinking agent with respect to the binder is 0.02 to 40% by mass, particularly preferably 0.5 to 30% by mass.

  The mass ratio of the vapor phase silica and the binder in the ink receiving layer (A1) of the present invention is 75:25 to 50:50, preferably 70:30 to 55:45, more preferably 70:30 to. 60:40. By setting the content in the above range, it is possible to obtain the adhesive strength between the ink receiving layer (A) and the transparent support, the effect of preventing cracks in the printed portion after ink jet recording, and the coating ability.

The coating amount of the ink receiving layer (A1) of the present invention is 0.5 to 8 g / m ² in terms of solid content, preferably 1 to 6 g / m ² , more preferably ^{2 to 4} g / m ² . It is. By setting it as the above range, it is possible to obtain the adhesive strength between the ink receiving layer (A) and the transparent support, and the effect of preventing cracks in the printed portion after ink jet recording.

  The mass ratio of the vapor phase silica and the binder in the ink receiving layer (A2) of the present invention is 95: 5 to 75:25, preferably 90:10 to 80:20. By setting the content in the above range, it is possible to prevent cracking of the ink receiving layer and to obtain high ink absorbability.

The coating amount of the ink receiving layer (A2) of the present invention is 5 to 50 g / m ² in solid content, preferably 10 to 40 g / m ² , and more preferably 13 to 35 g / m ^2. . By setting the content in the above range, it is possible to prevent cracking of the ink receiving layer and to obtain high ink absorbability.

  As described above, the ink-jet recording material of the present invention comprises at least two ink-receiving layers (A) containing vapor phase silica having an average secondary particle size of 300 nm or less and a binder, and the bottom layer is transparent. By providing the ink receiving layer (A1) having good adhesion to the support and the ink receiving layer (A2) having excellent ink absorbability as the uppermost layer, excellent transparency, ink absorbability, and ink receiving layer It can have adhesive strength with the support.

  The ink receiving layer (A) of the present invention may contain a cationic compound as an ink fixing agent. The cationic compound used here is the same cationic polymer or water-soluble metal compound as that used for dispersion and pulverization of the vapor phase silica fine particles. The cationic compound can improve the fixability of an anionic ink. Further, by containing a water-soluble metal compound, it is possible to prevent cracking, and as a result, it is possible to further reduce the amount of hydrophilic binder and further increase the amount of vapor-phase process silica in order to improve ink absorbability. . In particular, high effects can be obtained by incorporating these compounds in the ink receiving layer (A2).

  The ink receiving layer (A) of the present invention further includes a surfactant, a coloring dye / pigment, an ultraviolet absorber, an antioxidant, a dispersant, an antifoaming agent, a leveling agent, an antiseptic, a viscosity stabilizer, and a pH adjuster. Various oil droplets can be contained, but it is important that other properties such as transparency, adhesive strength, and ink absorbency are not adversely affected.

  In the ink receiving layer (A) of the present invention, if the ink receiving layer (A1) is provided in the lowermost layer and the ink receiving layer (A2) is provided in the uppermost layer, another ink absorbing layer, ink fixing layer, intermediate A layer or the like may be provided. However, it is important not to adversely affect other properties such as transparency, adhesive strength, and ink absorbency.

  In the present invention, a backing layer is provided on the surface opposite to the surface on which the ink receiving layer (A) is provided to prevent curling. The backcoat layer may further contain pigments, binders, antistatic agents, hardeners, surfactants, and the like for the purpose of antistatic and improved transportability.

  In the backing layer of the present invention, colloidal silica, preferably colloidal silica having an average primary particle size of 5 to 50 nm is contained as a pigment in order to maintain transparency and coating strength of the backing layer. Examples of colloidal silica that can be used include, for example, Snowtex ST-20, ST-30, ST-40, ST-C, ST-N, ST-20L, ST-O, ST-OL, ST from Nissan Chemical Industries, Ltd. -S, ST-XS, ST-XL, ST-YL, ST-ZL, ST-OZL, ST-AK, ST-AKL, ST-AKYL, etc. are commercially available, and Adelite from Asahi Denka Kogyo Co., Ltd. Are commercially available.

  The binder used in the backing layer of the present invention is not particularly limited, but is a polymer such as acrylonitrile-butadiene copolymer, acrylate polymer, vinyl acetate polymer, styrene-butadiene copolymer, or derivatives thereof. Alternatively, polyvinyl alcohol compounds, polyethylene glycol compounds, starches, dextrin, carboxymethyl cellulose, and derivatives thereof can be used. Preferably, the use of polyvinyl alcohol can effectively prevent the show-through of the solvent that evaporates from the recording portion when the recording materials after ink jet recording are superposed.

  The mass ratio of the colloidal silica and the binder in the backing layer of the present invention is 90:10 to 30:70, preferably 80:20 to 40:60, more preferably 70:30 to 50:50. is there. By making it into the above-mentioned range, it is possible to obtain cracking prevention of the backing layer and adhesion strength with the transparent support, and further, it is possible to obtain the show-through resistance and the anti-blocking effect.

  The backing layer of the present invention has an extremely low porosity as compared with the ink receiving layer and does not function as an ink receiving layer. The porosity of the backing layer in the present invention means the total solid content of the void volume, which is a value obtained by subtracting the total solid content such as inorganic fine particles and binder in the layer from the dry film thickness of the backing layer. The ratio to the capacity. The smaller the value, the better the show-through resistance. By setting the porosity of the backing layer to 70% by volume or less, preferably 50% by volume or less, more preferably 20% by volume or less, the effect of show-through resistance can be sufficiently obtained.

The coating amount of the backing layer is determined in consideration of the curl resistance of the resulting recording material. In the present invention, the coating amount is 3 to 18 g / m ² in terms of solid content, preferably 5 to 15 g / m. ² and more preferably 6 to 12 g / m ² . If it is less than 3 g / m ^2, the effect of preventing curling to the ink receiving surface side is small. Conversely, if it is more than 18 g / m ² , curling to the back surface becomes too large to handle, and the blocking preventing effect is also achieved. In addition, the problem arises that the printer head rubs against the recording material during printing by the ink jet printer.

  The ink-receiving layer (A2) and / or the backing layer of the present invention preferably contains a matting agent for improving the vacuum drawability. The matting agent that can be used is not particularly limited, but it is necessary that the transparency of the coating layer is not impaired. Preferably, at least one of an inorganic pigment and an organic pigment having an average secondary particle diameter of 3 to 20 μm is used as an ink receiving layer ( A2) and / or used for the backing layer. For example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, titanium dioxide, zinc oxide, zinc hydroxide, calcium silicate, magnesium silicate, synthetic silica, alumina, hydrated alumina, aluminum oxide, magnesium hydroxide, etc. And inorganic pigments such as polystyrene, polyethylene, polyacrylic acid ester, polymethacrylic acid ester, polyvinyl chloride, and urea resin. By including the matting agent, it is possible to improve the vacuum drawability in the contact exposure process. Although it should just be contained in the coating layer formed in the surface which contacts a printing plate, if both surfaces are contained, favorable vacuum drawability will be acquired even if which surface is made to contact.

When the matting agent is contained in the ink receiving layer (A2) and / or the backing layer, it is necessary to determine the content within a range that does not impair the transparency of the coating layer, and the content is 2 to 200 mg in terms of solid content. / M ² , preferably 5 to 120 mg / m ² , more preferably 10 to 60 mg / m ² . By setting it in the above range, both transparency and suitability for vacuuming can be achieved.

  Examples of the transparent support used in the present invention include polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate, diacetate resins, triacetate resins, cellulose ester resins such as nitrocellulose and cellulose acetate, and polyolefin resins. And plastic resin films such as acrylic resin, polycarbonate resin, polyvinyl chloride, polyimide resin, polysulfone, polyphenylene oxide, cellophane, and celluloid. In particular, a polyester resin film is preferably used in terms of characteristics such as heat resistance and price. The thickness of these resin film supports is preferably about 50 to 250 μm from the viewpoint of curling properties and ease of handling.

  When adjusting the transparency and color tone of the transparent support, for example, it is prepared by blending inorganic fine particles with a thermoplastic resin. Examples of the inorganic fine particles include calcium carbonate, titanium dioxide, talc, silica, carbon black, etc. Can be used. For example, a blue PET film colored in blue is preferably used for medical purposes.

  When the ink receiving layer coating liquid is applied to a transparent support such as a plastic resin film, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, plasma treatment and the like are usually performed prior to coating.

  It is preferable to provide a primer layer mainly composed of a natural resin or a synthetic resin on a transparent support such as a plastic resin film. The primer layer is provided on the support with a film thickness (dry film thickness) of 0.01 to 5 μm, preferably in the range of 0.05 to 5 μm.

  In the present invention, the method for applying the ink receiving layer (A) and the backing layer is not particularly limited. When two or more layers are applied simultaneously, application devices such as a slide bead coater, curtain coater, and extrusion coater can be used. For continuous application, combinations of the above-mentioned application devices, air knife coaters, rod coaters, blades It can apply | coat continuously with a coater etc. and said coating device. In the present invention, simultaneous application means that the respective layers are applied almost simultaneously, and continuous application means that the upper layer is continuously applied in a short time (usually within about 10 seconds) without a drying step after lower layer application. In view of the uniformity of the ink receiving layer, simultaneous application is preferred.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. Parts and% indicate the solid content or the mass part or mass% of the substantial component.

The transparency support shown below was prepared.
<Transparency support>
A primer layer having the following composition was provided on both sides of a polyethylene terephthalate film having a thickness of 100 μm (haze value 1%) so as to have a dry film thickness of 0.3 μm, and subjected to high-frequency corona discharge treatment.

<Composition of primer layer>
Latex (weight average molecular weight 42000) of vinylidene chloride: methyl acrylate: acrylic acid (90: 9: 1, mass%).

<Application of backing layer>
100 parts of colloidal silica (manufactured by Nissan Chemical Industries, Snowtex O, average primary particle size 10-20 nm), 50 parts of polyvinyl alcohol (saponification degree 88%, average polymerization degree 3500), 7 parts of boric acid, surfactant Add 0.3 parts sequentially, and finally add water to a concentration of 10% by mass to form a coating solution for the backing layer. The solid coating amount is applied to one side of the transparent support with a slide coating test coater. It was applied and dried so as to be 10 g / m ² .

<Application of ink receiving layer (A)>
On the surface opposite to the surface on which the backing layer of the light-transmitting support is provided, the following ink-receiving layer (A1) coating solution is used as a lower layer so that the solid content coating amount is 3 g / m ² , and The ink-receiving layer (A2) coating liquid was used as an upper layer, and a multilayer coating was performed with a slide bead coater so that the solid content coating amount was 20 g / m ² , and dried to obtain the ink jet recording material of Example 1. The mass ratio of the vapor phase method silica to the polyvinyl alcohol used as the binder is 69:31 in the ink receiving layer (A1) and 82:18 in the ink receiving layer (A2).

<Ink-receiving layer (A1) coating solution>
Concentration of 100 parts of vapor phase silica having an average primary particle size of 7 nm and a specific surface area of 300 m ² / g by BET method, and 4 parts of dimethyl diallyl ammonium chloride homopolymer (Charol DC902P manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Is dispersed in water so as to be 20% by mass, and is atomized using a high-pressure homogenizer (manufactured by APV Gourin Co., Ltd., 15MR-8TA type), and a gas phase method silica dispersion having an average secondary particle size of 150 nm is obtained. Produced. To this dispersion, 6 parts of boric acid, 45 parts of polyvinyl alcohol (saponification degree 88%, average polymerization degree 3500), and 0.3 part of surfactant are sequentially added to 100 parts of vapor phase method silica, and finally 10 parts. Water was added so as to have a concentration of mass% to prepare an ink receiving layer (A1) coating solution.

<Ink-receiving layer (A2) coating solution>
In the gas phase method silica dispersion used in the above <ink receiving layer (A1) coating solution>, 3 parts of boric acid, polyvinyl alcohol (saponification degree 88%, average polymerization degree 3500) 22 with respect to 100 parts of gas phase method silica 22 And 0.3 part of a surfactant were sequentially added, and finally water was added so as to obtain a concentration of 12% by mass, whereby an ink receiving layer (A2) coating solution was obtained.

  The inkjet recording material of Example 2 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink-receiving layer (A1) coating solution> was changed to 35 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A1) and the binder is 74:26.

  The inkjet recording material of Example 3 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink-receiving layer (A1) coating solution> was changed to 95 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A1) and the binder is 51:49.

  The inkjet recording material of Example 4 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink-receiving layer (A2) coating solution> was changed to 11 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A2) and the binder is 90:10.

  The inkjet recording material of Example 5 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink receiving layer (A2) coating solution> was changed to 30 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A2) and the binder is 77:23.

  The gas phase method silica used in the ink receiving layers (A1) and (A2) of Example 1 was changed to gas phase method silica having an average primary particle size of 12 nm and an average secondary particle size after dispersion of 230 nm. Were carried out in the same manner to obtain an ink jet recording material of Example 6.

  The same procedure as in Example 7 was carried out except that the binder used in the ink receiving layer (A1) of Example 1 was changed from polyvinyl alcohol to styrene-butadiene copolymer resin, and boric acid was removed. Thus, an inkjet recording material of Example 7 was obtained. It was. The mass ratio of vapor phase silica to binder is 69:31.

The ink jet recording material of Example 8 was obtained in the same manner except that the solid coating amount of the backing layer of Example 1 was 16 g / m ² .

The ink jet recording material of Example 9 was obtained in the same manner except that the solid coating amount of the backing layer of Example 1 was changed to 4 g / m ² .

  The same procedure as in Example 10 was carried out except that the binder used in the backing layer of Example 1 was changed from polyvinyl alcohol to styrene-butadiene copolymer resin, and boric acid was removed. Thus, an inkjet recording material of Example 10 was obtained.

The ink receiving layer (A2) of Example 1 contains polystyrene particles (average particle size 17 μm) as a matting agent at 15 mg / m ^2, and the backing layer also contains 20 mg / m ^2. 11 inkjet recording materials were obtained.

(Comparative Example 1)
The vapor phase silica used in the ink receiving layers (A1) and (A2) of Example 1 was changed to vapor phase silica having an average primary particle diameter of 40 nm and an average secondary particle diameter after dispersion of 320 nm. Were carried out in the same manner to obtain an ink jet recording material of Comparative Example 1.

(Comparative Example 2)
An ink jet recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink receiving layer (A1) coating solution> was changed to 30 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A1) and the binder is 77:23.

(Comparative Example 3)
An ink jet recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink receiving layer (A1) coating solution> was changed to 120 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A1) and the binder is 45:55.

(Comparative Example 4)
An ink jet recording material of Comparative Example 4 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink receiving layer (A2) coating solution> was changed to 2. The mass ratio of the vapor phase silica contained in the ink receiving layer (A2) and the binder is 98: 2.

(Comparative Example 5)
An ink jet recording material of Comparative Example 5 was obtained in the same manner as in Example 1 except that the number of parts of polyvinyl alcohol in the <ink receiving layer (A2) coating solution> was changed to 43 parts. The mass ratio of the vapor phase silica contained in the ink receiving layer (A2) and the binder is 70:30.

(Comparative Example 6)
An ink jet recording material of Comparative Example 6 was obtained in the same manner except that the ink receiving layer (A1) of Example 1 was not provided.

(Comparative Example 7)
An ink jet recording material of Comparative Example 7 was obtained in the same manner except that the ink receiving layer (A2) of Example 1 was not provided.

(Comparative Example 8)
An ink jet recording material of Comparative Example 8 was obtained in the same manner except that the solid coating amount of the backing layer of Example 1 was 20 g / m ² .

(Comparative Example 9)
An ink jet recording material of Comparative Example 9 was obtained in the same manner as in Example 1 except that the solid content coating amount of the backing layer was changed to 2 g / m ² .

(Comparative Example 10)
A comparative example was carried out in the same manner except that the colloidal silica contained in the backing layer of Example 1 was changed to wet method silica (manufactured by Mizusawa Chemical Industry Co., Ltd., Mizukasil P-527, average secondary particle size 1.6 μm). Ten inkjet recording materials were obtained.

(Comparative Example 11)
An ink jet recording material of Comparative Example 11 was obtained in the same manner except that the colloidal silica contained in the backing layer of Example 1 was removed.

(Comparative Example 12)
An ink jet recording material of Comparative Example 12 was obtained in the same manner except that the backcoat layer of Example 1 was not provided.

  The ink jet recording material produced as described above was evaluated as follows. The results are shown in Table 1.

<Transparency>
Transparency was evaluated by measuring the haze value of the produced inkjet recording material. The haze value was measured using POIC HAZEMETER SEP-HS-D1 manufactured by Nippon Seimitsu Optical Co., Ltd.
○: Haze value is 10% or less, and high transparency is obtained.
(Triangle | delta): A haze value is the range of 10 to 20%, and transparency is a little low, but there is no problem practically.
X: Haze value is 20% or more, transparency is low and practical use is not possible.

<Ink absorbability>
Color (C, M, Y) letters were printed on the ink receiving surface of the ink jet recording material with a Seiko Epson ink jet printer PM-7000C under the conditions of 23 ° C. and 50% RH, and ink bleeding was evaluated.
○: There is no problem in recognizing characters without bleeding.
Δ: Although there is a slight blur of characters, there is no problem in recognizing.
X: Characters are greatly blurred and cannot be recognized.

<Cracks in printing section>
The ink-receiving surface of the ink-jet recording material was printed with solid (C, M, Y) and black with a Seiko Epson ink-jet printer PM-7000C under the conditions of 23 ° C. and 50% RH, and then left to stand for 3 days before printing. The crack of the part was observed.
○: There is no problem with no cracks in the printed part.
Δ: Although there is some cracks in the printed part, there is no practical problem.
X: The printed part is cracked and the image has a large adverse effect.

<Blocking resistance after printing>
Solid ink was printed in color (C, M, Y) and black with Seiko Epson ink jet printer PM-7000C under conditions of 23 ° C. and 50% RH on the ink receiving surface of the ink jet recording material, and the ink was completely absorbed. Immediately after that, the printing surface was overlapped with the back surface of the same material, and after 50 sheets were similarly stacked, the blocking resistance after leaving at 40 ° C. for 24 hours was evaluated.
○: No blocking at all.
Δ: Slightly blocking but practical.
X: The blocking is large and the actual use is impossible.

<Resistance to show-through after printing>
After the evaluation of <blocking resistance after printing>, the ink, water derived from the ink and the show-through of the solvent were observed and evaluated.
○: There is no show-through.
Δ: Slightly show-through but practical.
X: The show-through is large and cannot be used.

<Adhesive strength between ink receiving layer and transparent support>
The ink-jet recording material was bent with the ink-receiving surface removed at 13 ° C. and 20% RH, and the degree of peeling of the ink-receiving layer at that portion was observed. In addition, the observation of powder falling from the edge by cutting and the peel test using a cello tape were performed to comprehensively evaluate the adhesive strength between the ink receiving layer and the transparent support.
○: The ink receiving layer does not peel off and has excellent adhesive strength.
Δ: The ink receiving layer peels off slightly when bent greatly, or the edge peels off slightly during cutting, but there is no practical problem.
X: The ink receiving layer peels off easily and cannot be practically used.

<Curl resistance>
The obtained inkjet recording material was cut into a size of 297 mm × 420 mm, and the average value of curls at the four corners of the unprinted recording material in an atmosphere of 13 ° C. and 20% RH was determined as follows. The curl toward the ink receiving surface side was defined as a curl toward the plus (+) side, and the curl toward the back surface side was defined as a curl toward the minus (−) side.
○: It is in the range of −5 mm to +5 mm.
(Triangle | delta): It exists in the range of -10mm-+ 10mm.
X: Curling exceeding ± 10 mm occurs.

<Vacuum drawability>
The obtained ink jet recording material was cut into a size of 297 mm × 420 mm, and images including fine lines of various thicknesses were printed on the ink receiving surface using an ink jet printer PM-7000C manufactured by Seiko Epson Corporation. The recording surface of the recording material after printing is overlapped with the photosensitive surface of the printing plate, set in an exposure apparatus (HMW201 manufactured by Oak Manufacturing Co., Ltd.), the exposure apparatus is evacuated, and after a certain evacuation time has passed, the final The image formed on the printing plate was observed.
○: Fine line reproducibility is good and no bleeding is observed.
Δ: Slight blotting on fine lines, but no problem in practical use.
X: The blur of the fine line is large and the image is blurred, and cannot be practically used.

From the above results, an ink jet recording material provided with an ink receiving layer (A) comprising at least two layers containing vapor phase silica having an average secondary particle diameter of 300 nm or less and a binder on one side of a transparent support. In the ink receiving layer (A), the mass ratio of the vapor phase silica and the binder contained in the ink receiving layer (A1) closest to the transparent support is 75:25 to 50:50. The mass ratio of the vapor phase silica and the binder contained in the ink receiving layer (A2) farthest from the transparent support in the ink receiving layer (A) is 95: 5 to 75:25, In addition, a backing layer containing colloidal silica and a binder is provided on the surface opposite to the surface on which the ink receiving layer (A) is provided in the range of ³ to 15 g / m ^{2 in} terms of the solid content coating amount. Transparency, ink absorption, ink reception The adhesive strength between the layer and the transparent support, curl resistance, could be obtained an ink jet recording material which has both 耐裏-through property. Since the adhesive strength could be greatly improved, the recording material was bent or bent, so that it became an ink jet recording material suitable for use in a large format where the frequency of occurrence of peeling of the coating layer was high. The ink-jet recording material of Example 11, which was excellent in vacuum drawability because the ink receiving surface was matted, had the backing layer provided with a matte surface so that the surface provided with the backing layer was the printing plate. Even when they are superposed on the photosensitive surface, they exhibit excellent evacuation suitability, which is a particularly preferred embodiment for a printing plate underfilm.

On the other hand, the ink jet recording material of Comparative Example 1 using vapor phase silica having an average secondary particle diameter of greater than 300 nm had low transparency and large ink bleeding in the printing area. Further, the ink jet recording material of Comparative Example 2 could not obtain sufficient adhesive strength due to the insufficient amount of the binder in the ink receiving layer (A1). Next, in the ink jet recording material of Comparative Example 3, since the amount of the binder in the ink receiving layer (A1) was excessive, the solid print portion was cracked, resulting in a large adverse effect on the image. Next, the ink jet recording material of Comparative Example 4 has low transparency due to the occurrence of fine cracks on the coated surface due to the insufficient amount of the binder in the ink receiving layer (A2), and the ink in the printing area is not good. The blur was large and the curl to the ink receiving surface side was too large. Next, the ink jet recording material of Comparative Example 5 was inferior in ink absorbability due to the excessive amount of binder in the ink receiving layer (A2). Next, the ink jet recording material of Comparative Example 6 in which the ink receiving layer (A1) was not provided was not at a level that could withstand actual use as an ink jet recording material because the ink receiving layer was easily peeled off from the transparent support. It was. Next, the ink jet recording material of Comparative Example 7 in which the ink receiving layer (A2) was not provided had a large and insufficient ink absorbability. Next, the ink jet recording materials of Comparative Example 8 in which the solid coating amount of the backing layer was 20 g / m ² and Comparative Example 9 in which the solid coating amount was 2 g / m ² had excessively negative curls on the negative side and positive side, respectively. This adversely affected printer transportability. Next, the ink jet recording material of Comparative Example 10 in which the colloidal silica contained in the backing layer is changed to a wet process silica has a low transparency of the backing layer, is inferior in blocking resistance, and further contains water and solvent. The show-through part was easily visible. Next, the inkjet recording material of Comparative Example 11 which did not contain colloidal silica in the backing layer was inferior in blocking resistance after printing. Finally, the inkjet recording material of Comparative Example 12 in which no backcoat layer was provided was inferior in blocking resistance, show-through resistance, and curl resistance.

Claims (4)

In the ink jet recording material, an ink receiving layer (A) comprising at least two layers containing vapor phase silica having an average secondary particle size of 300 nm or less and a binder is provided on one side of a transparent support. Among the receiving layers (A), the mass ratio of the vapor phase silica and the binder contained in the ink receiving layer (A1) closest to the transparent support is 75:25 to 50:50, and the ink receiving The mass ratio of the vapor phase silica contained in the ink receiving layer (A2) farthest from the transparent support in the layer (A) to the binder is 95: 5 to 75:25, and the ink receiving A backing layer containing colloidal silica and a binder is provided on the surface opposite to the surface on which the layer (A) is provided in the range of ³ to 18 g / m ^{2 in} terms of solid content. An ink jet recording material.   2. The ink jet recording material according to claim 1, wherein an average primary particle diameter of vapor phase silica contained in the ink receiving layer (A) is 20 nm or less.   The ink jet recording material according to claim 1 or 2, wherein the binder contained in the ink receiving layer (A1) is polyvinyl alcohol.   The matting agent having an average secondary particle diameter of 3 to 20 µm is contained in the ink receiving layer (A2) farthest from the transparent support and / or the backing layer in the ink receiving layer (A). The ink jet recording material according to any one of 1, 2 and 3.