JP2003191596A - Method for forming image on ink jet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an image on an ink jet recording material improved in image preservability while holding a photographic quality feeling and glossiness. <P>SOLUTION: After an image is formed on the ink jet recording material wherein at least one ink receiving layer is provided on a support, the surface of the image is overcoated with a solution of polyvinyl alcohol with a polymerization degree of 2,100 or more. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for an ink jet recording material, and more particularly to an image forming method for an ink jet recording material having a photo-like high gloss and improved storability after printing. It is about.

[0002]

2. Description of the Related Art As a recording material used in an ink jet recording system, a pigment such as amorphous silica or alumina and a water-soluble binder such as polyvinyl alcohol are provided on a support called ordinary paper or ink jet recording paper. A recording material having a porous ink absorbing layer is known.

For example, JP-A-55-51583 and JP-A-5-51583.
No. 6-157, No. 57-107879, No. 57-10.
No. 7880, No. 59-230787, No. 62-160.
No. 277, No. 62-184879, No. 62-1833.
No. 82 and No. 64-11877, there are proposed recording materials obtained by coating a paper support with a silicon-containing pigment such as silica together with an aqueous binder.

Further, Japanese Patent Publication No. 3-56552 and Japanese Patent Laid-Open No. Hei 2
-188287, 10-81064, 10-1
19423, 10-175365, 10-19.
No. 3776, No. 10-203006, No. 10-217.
No. 601, No. 11-20300, No. 11-20306
JP-A-11-34481 and the like disclose the use of synthetic silica fine particles by a vapor phase method (hereinafter referred to as vapor phase silica). The vapor-phase method silica is an ultrafine particle having an average primary particle diameter of several nm to several tens of nm, and is characterized by high gloss. Further, Japanese Patent Laid-Open No. 2-2
766771, 3-251488, 5-16517 and the like disclose recording materials using alumina hydrate.

In recent years, with the demand for photo-like recording sheets, the glossiness has become more and more important, and polyolefin resin-coated paper (paper whose both surfaces are laminated with a polyolefin resin such as polyethylene) or polyester film, etc. A recording material in which an ink receiving layer mainly composed of vapor phase silica, alumina or the like is coated on the water resistant support is used advantageously.

However, since the porous recording material using inorganic fine particles such as vapor-phase method silica is porous,
There is a problem that the printed image is easily discolored during storage after printing. That is, there is a big problem that discoloration or fading easily occurs due to light or a trace gas in the atmosphere.
In addition, in the water-resistant support, unlike the conventionally used paper support, since the support itself has no ink absorbing ability, the porosity of the porous recording layer is increased and the coating amount is increased. Therefore, it is necessary to secure the ink absorption capacity. As a result of such a design, the above-described image discoloration problem has become particularly serious.

Many proposals have been made in the past for the purpose of suppressing such discoloration and fading and improving the storability of printed images. For example, JP-A-57-74193
No. 57-87988 and No. 62-261478, a method using an ultraviolet absorber is also disclosed in JP-A-57-
74192, 57-87989, 60-727.
No. 85, No. 61-146591, No. 61-15498.
No. 9, No. 62-170381, No. 62-61477.
No. 3, JP-A-3-13376, and JP-A-7-314881,
7-314882, 8-25796, 9-2
No. 67544 and the like describe a method using an antioxidant or an anti-fading agent. However, all of these methods have an adverse effect such that the discoloration / fading prevention effect is insufficient, or even if the discoloration prevention effect is obtained, the coloring itself or the recording dye is discolored immediately after printing. There are many things that come out, and the current situation is that they have not reached the level of practical application.

On the other hand, a number of techniques have been proposed in which a coating layer is provided on the surface of an image after printing to improve the image storability by the protective action thereof, for example, JP-A-8-1187.
Japanese Patent Laid-Open No. 8-1749 discloses a method of forming a protective layer by irradiating ultraviolet rays after applying an ultraviolet curable resin.
No. 89 discloses a method of thermally transferring a thermoplastic resin layer as an overcoat layer, and JP-A-8-252985 discloses a method of providing a transparent film containing methyl methacrylate on a formed image. A technique of protecting the image surface by laminating is also known, and for example, there is a method described in JP-A-9-262971. However, the image recording material obtained by these methods has the above-mentioned gas fading improved, but has a polymer protective layer on the surface which is not present in an actual silver salt photograph, and thus reproduces the texture peculiar to the photograph. I had a problem with.

Further, in Japanese Patent Laid-Open No. 2000-280601,
A technique for improving light resistance by providing a protective layer containing an ultraviolet absorber and an antioxidant on the image recording layer is disclosed. There is no description regarding silica, and although polyvinyl alcohol is described as a specific example of the material used as the protective layer, there is no description regarding the influence of the degree of polymerization and the coating amount on the image preservation effect.
Further, in JP-A-2001-213044, after an image is formed on a recording material having a void layer containing inorganic fine particles, the surface of the image is covered with a coating layer having an oxygen permeability of a specific value or less with respect to a support. However, there is no description about the degree of polymerization and the coating amount with respect to the image preservation effect in the case of using polyvinyl alcohol as the coating layer. As described above, in the field of inkjet recording materials aiming at photo-like, when polyvinyl alcohol is used as an image protective layer, there has been no knowledge about the influence of the polymerization degree and the coating amount on the image storage effect. Further, even with the above-mentioned known technology, a method for completely clearing various problems relating to image storability such as gas resistance and light resistance has not been found,
Further improvements were desired.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming method for an ink jet recording material, which has an improved image storability while maintaining a photo-like texture and glossiness. is there.

[0011]

The above object of the present invention is to form an image on an ink jet recording material having at least one ink receiving layer on a support and then overcoat with a solution of polyvinyl alcohol having a degree of polymerization of 2100 or more. And an image forming method for an ink jet recording material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording material of the present invention has at least one ink receiving layer, and the ink receiving layer is a so-called void type which mainly contains inorganic fine particles, It may be a swelling type that mainly contains a water-soluble polymer. In the present invention, the former type is preferable. The above-mentioned void type allows ink to be absorbed into the voids formed in the film, and it is necessary to increase the void volume in order to exhibit high ink absorbency. Therefore, it is necessary to coat a relatively large amount of inorganic fine particles on the support, and the amount of the hydrophilic binder is preferably reduced in order to increase the porosity.

The inorganic fine particles used in the present invention include:
Light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate,
Satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic silica, alumina, alumina hydrate,
Examples thereof include magnesium silicate, lithopone, zeolite and magnesium hydroxide. Among these, synthetic silica and alumina fine particles (alumina, alumina hydrate) are preferable, and vapor phase silica and alumina fine particles are particularly preferable. These may be used alone or in combination. In particular, in the case of a combination of vapor-phase method silica and alumina fine particles, the image density and the image storability can be improved by mixing them in the same layer or by using them in separate layers to form a laminated form.

The vapor-phase process silica preferably used in the present invention is also called dry process silica and is generally produced by a flame hydrolysis method. Specifically, a method in which silicon tetrachloride is burnt together with hydrogen and oxygen is generally known. Vapor phase silica is commercially available as Aerosil from Nippon Aerosil Co., Ltd. and QS type from Tokuyama Corp., and can be obtained. In general, vapor-phase method silica is aggregated into secondary particles having appropriate voids.
It is preferable that the particles are pulverized and dispersed by an ultrasonic wave, a high-pressure homogenizer, an opposed collision type jet pulverizer or the like until the secondary particles of about 0 to 300 nm are obtained, because the ink absorbability and glossiness are good.

Alumina fine particles (alumina and alumina hydrate) preferably used in the present invention are aluminum oxide and its hydrate, which may be crystalline or amorphous.
Those having an irregular shape, a spherical shape, a plate shape, or the like are used. As the alumina, γ-alumina which is a γ-type crystal of aluminum oxide is preferable. γ-alumina can reduce the primary particles to about 10 nm,
Usually, a secondary particle crystal of several thousands to tens of thousands nm is subjected to ultrasonic waves, a high pressure homogenizer, a counter collision type jet crusher, etc.
Those pulverized to about 300 nm can be preferably used. Alumina hydrate is Al ₂ O ₃ · nH ₂ O (n = 1 to 1
It is represented by the constitutive equation of 3). When n is 1, it represents an alumina hydrate having a boehmite structure, and when n is more than 1 and less than 3, it is an alumina hydrate having a pseudo-boehmite structure. Hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali,
It can be obtained by a known production method such as hydrolysis of an aluminate.

The average particle diameter of the primary particles of the fumed silica, alumina, and alumina hydrate of the present invention means that the dispersed particles exist within a certain area by observing the dispersed particles with an electron microscope.
The diameter of a circle equal to the projected area of each individual particle was determined as the particle size of the particle. The average particle size of the primary particles of the vapor-phase method silica used in the present invention is 5 to 50 nm, preferably 5 to 50 nm.
It is 30 nm. The average particle diameter of the primary particles of the alumina and alumina hydrate of the present invention is 10 to 50 nm, preferably 10 to 30 nm.

In the present invention, the amount of the inorganic fine particles used in the recording layer is preferably 8 g / m ² or more, and 10 to 30 g / m ^2.
The range of m ² is more preferable. If it is less than this range, the ink absorbency is inferior, and if it is more than this range, the strength of the ink receiving layer is lowered, which tends to cause a problem during production or use.

In the present invention, the inorganic fine particles are mainly contained in the ink receiving layer, that is, 50% by weight or more, preferably 60% by weight or more, more preferably 65% by weight, of the inorganic fine particles based on the total solid content of the ink receiving layer. It is preferable to contain the above.

In the present invention, as the hydrophilic binder used together with the inorganic fine particles, various known binders can be used, but a hydrophilic binder having high transparency and high ink permeability can be preferably used. In using the hydrophilic binder, it is important that the hydrophilic binder does not swell and block the voids at the initial penetration of the ink. From this viewpoint, a hydrophilic binder having a low swelling property at around room temperature is preferable. Used. Particularly preferred hydrophilic binders are fully or partially saponified polyvinyl alcohol or cation-modified polyvinyl alcohol.

Among the polyvinyl alcohols, those partially or completely saponified with a saponification degree of 80% or more are particularly preferable. Those having an average degree of polymerization of 200 to 5000 are preferable.

As the cation-modified polyvinyl alcohol, for example, as described in JP-A No. 61-10483, primary to tertiary amino groups or quaternary ammonium groups are added to the main chain or side chain of polyvinyl alcohol. It is polyvinyl alcohol contained therein.

In the present invention, it is preferable to use a crosslinking agent (hardening agent) together with the above hydrophilic 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, US Patent No. 2,73
N-methylol compounds as described in US Pat. No. 2,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. Nos. 3,017,280 and 2,983.
No. 611, aziridine compounds, US Pat. No. 3,100,704, carbodiimide compounds, US Pat. No. 3,091,537, epoxy compounds, mucochloric acid, halogen carboxaldehydes, There are dioxane derivatives such as dihydroxy dioxane, chromium alum, zirconium sulfate, inorganic cross-linking agents such as boric acid and borate, and these may be used alone or in combination of two or more. Among these, boric acid or borate is particularly preferable.

In the present invention, as the polyvinyl alcohol used for the overcoat, the completely or partially saponified polyvinyl alcohol and the cation-modified polyvinyl alcohol described in the example of the ink receiving layer, and various modifications such as silanol modification and alkyl modification are used. Polyvinyl alcohol is mentioned, and the degree of polymerization thereof is 2100 or more. Further, the upper limit of the degree of polymerization is suitably about 5000. The preferred degree of polymerization of the polyvinyl alcohol used in the present invention is in the range of 2400 to 5000, more preferably 2800 to 4500. Many polyvinyl alcohols having a degree of polymerization of less than 2100 have poor film-forming properties, and it is difficult to simultaneously achieve a high image storage effect and reproduction of a photo-like texture. Also a preferred amount of coating, 0.05~4g / m ^2, more preferably 0.07~2g / m ^2, more preferably 0.1 to 1 g /
m ² . If it is less than this range, the effect of improving gas resistance cannot be obtained, and if it is more than this range, the liquid amount of the overcoat liquid becomes relatively large, which is not preferable because it causes poor drying after coating and uneven gloss.

In the present invention, the polyvinyl alcohol solution overcoated on the image surface contains polyvinyl alcohol in an amount of 0.1 to 15% by weight, preferably 0.3 to 1.
It is an aqueous solution containing 0% by weight, more preferably 0.5 to 5% by weight. Further, in the aqueous solution, a water-soluble organic solvent such as an alcohol solvent, a surfactant, a crosslinking agent as described above,
It may contain various image preservatives, preservatives and the like known in the inkjet field. The overcoat liquid containing this polyvinyl alcohol is preferably applied to the image surface in a moisture application amount of 5 to 30 g / m ² , more preferably 10 to 30 g / m ² . Thus, the degree of polymerization is 210
Applying zero or more polyvinyl alcohol solutions
There is an advantage that a higher gas resistance effect can be obtained with a thinner film, as compared with the case where a film (film) formed in advance is simply transferred onto the image surface or laminated. In addition, thinning the film of the overcoat has an advantage that the original texture and gloss of the photo-like inkjet recording material are less changed. As the coating method of the above-mentioned overcoat liquid, a coating method such as air spray, paint roll, wire bar, and brush can be used. Further, the liquid properties may be appropriately controlled and overcoating may be performed by various inkjet methods. In that case, it is sufficient that a uniform coating film can be obtained, and therefore it is not always necessary that the droplets are extremely fine, and droplets of 100 picoliters or less may be used. After applying a uniform coating film by these various methods, it may be dried by a suitable drying method at room temperature or in a heating atmosphere.

According to a preferred embodiment of the present invention, the surface pH of the membrane is 3 to 3 on the water-resistant support in combination with the inorganic fine particles.
6, preferably by image forming on the surface of an ink jet recording material having an ink receiving layer having a pH of 3 to 5.5, and then overcoating the image surface with a solution of polyvinyl alcohol having a polymerization degree of 2100 or more, preferably 2400 or more. The image storability after printing can be significantly improved while maintaining the photo-like texture and gloss.

According to another preferred embodiment of the present invention, the film surface p is combined with the fumed silica or alumina fine particles.
After an image is formed on the surface of an ink jet recording material containing a cationic compound in the ink receiving layer of H3 to 6, preferably pH 3 to 5.5, the degree of polymerization of 210 on the image surface.
By overcoating a solution of 0 or more, preferably 2400 or more of polyvinyl alcohol, the image storability after printing can be significantly improved while maintaining the photo-like texture and gloss.

Examples of the cationic compound used in the present invention include cationic polymers and water-soluble metal compounds. As the cationic polymer, polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, 5
9-33176, 59-33177, 59-1
No. 55088, No. 60-11389, No. 60-499.
No. 90, No. 60-83882, No. 60-109894
No. 62-198493, No. 63-49478,
63-115780, 63-280681, JP-A-1-40371, 6-234268, 7-.
Polymers having a primary to tertiary amino group and a quaternary ammonium group described in JP-A-125411 and JP-A-10-193776 are preferably used. The molecular weight of these cationic polymers is preferably 5,000 or more, more preferably about 5,000 to 100,000. The amount of these cationic polymers used is 1 to 10% by weight, preferably 2 to 7% by weight, based on the inorganic fine particles.

Examples of the water-soluble metal compound used in the present invention include water-soluble polyvalent metal salts. Examples thereof include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, magnesium, tungsten and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride. Dicopper, ammonium chloride copper (II) dihydrate, copper sulfate, cobalt chloride,
Cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel ammonium ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum sulfite, Aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate,
Ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zirconium acetate, zirconium chloride, chloride Zirconium oxide octahydrate, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium citrate tungsten, 12 tungstophosphate n Hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate and the like can be mentioned.

In the present invention, a water-soluble aluminum compound or a water-soluble compound containing a group 4A element of the periodic table is particularly preferable. As the water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or its hydrate, aluminum sulfate or its hydrate, ammonium alum and the like are known. Further, there is a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer. Particularly, a basic polyaluminum hydroxide compound is preferable.

The basic polyaluminum hydroxide compound is represented by the following general formula 1, 2 or 3 and has, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ ,
It is a water-soluble polyaluminum hydroxide which stably contains basic and polymeric polynuclear condensed ions such as [Al ₁₃ (OH) ₃₄ ] ⁵⁺ and [Al ₂₁ (OH) ₆₀ ] ³⁺ . .

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

These are water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., under the name of polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd. It is marketed by Riken Green under the name Purachem WT and from other manufacturers for the same purpose, and various grades are easily available. In the present invention, these commercially available products can be used as they are,
Some have an inappropriately low pH, and in that case, the pH can be adjusted appropriately before use.

The water-soluble compound containing an element of Group 4A of the periodic table used in the present invention is not particularly limited as long as it is water-soluble, but a water-soluble compound containing titanium or zirconium is preferable.
For example, as the water-soluble compound containing titanium, titanium chloride,
Titanium sulfate is a water-soluble compound containing zirconium, zirconium acetate, zirconium chloride, zirconium oxychloride, zirconium hydroxychloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium carbonate ammonium, zirconium carbonate potassium, zirconium sulfate. , Zirconium fluoride compounds and the like are known. Some of these compounds have an inappropriately low pH, and in that case, the pH can be adjusted appropriately before use. In the present invention, the term "water-soluble" means that it dissolves in water at 1% by weight or more under normal temperature and pressure.

In the present invention, the content of the water-soluble metal compound in the ink receiving layer is 0.
It is preferably 1 to 10% by weight, more preferably 1 to 5% by weight.

Two or more of the above-mentioned cationic compounds can be used in combination. For example, it is preferable to use a cationic polymer and a water-soluble metal compound in combination.

In the present invention, the film surface pH of the ink receiving layer
J. Surface pH measured after 30 seconds with distilled water according to the method described in TAPPI Paper Pulp Test Method N0.49.

The pH of the ink receiving layer is preferably adjusted at the stage of the coating liquid, but since the pH of the coating liquid and the film surface pH in the coated and dried state do not always match, the coating liquid and the film surface pH It is necessary to previously obtain the relationship between and by an experiment or the like in order to obtain a predetermined film surface pH. The pH of the ink receiving layer coating liquid is determined by appropriately combining acid or alkali. As the acid, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid, and organic acids such as acetic acid, citric acid and succinic acid are used, and as the alkali, sodium hydroxide, aqueous ammonia, potassium carbonate, trisodium phosphate. Alternatively, as the weak alkali, an alkali metal salt of a weak acid such as sodium acetate is used.

The ink receiving layer of the present invention may further contain various oil droplets in order to improve the brittleness of the film.
Examples of such oil droplets are hydrophobic high-boiling point organic solvents having a solubility in water at room temperature of 0.01% by weight or less (for example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, etc.) and polymer particles ( For example, particles obtained by polymerizing one or more polymerizable monomers such as styrene, butyl acrylate, divinylbenzene, butyl methacrylate, hydroxyethyl methacrylate) can be contained. Such oil droplets can be preferably used in the range of 10 to 50% by weight based on the hydrophilic binder.

In the present invention, a surfactant can be added to the ink receiving layer. The surfactant used may be any of anionic type, cationic type, nonionic type, betaine type, and low molecular weight type or high molecular weight type. One or more kinds of surfactants are added to the ink receiving layer coating liquid. When two or more kinds of surfactants are used in combination, anionic type and cationic type are used in combination. Is not preferable. The addition amount of the surfactant is preferably 0.001 to 5 g with respect to 100 g of the binder constituting the ink receiving layer,
More preferably, it is 0.01 to 3 g.

In the present invention, the ink receiving layer further comprises
Various known additives such as coloring dyes, coloring pigments, fixing agents for ink dyes, ultraviolet absorbers, antioxidants, pigment dispersants, defoamers, leveling agents, preservatives, optical brighteners, viscosity stabilizers, etc. Can also be added.

The support used in the present invention is preferably a water resistant support. As the water resistant support, polyester resin such as polyethylene terephthalate, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride, polyimide resin, cellophane, plastic resin film such as celluloid, and polyolefin resin on both sides of paper The resin-coated paper laminated with is mentioned. The thickness of the water resistant support used in the present invention is preferably about 50 to 300 μm.

The base paper constituting the resin-coated paper preferably used in the present invention is not particularly limited, and commonly used paper can be used, but more preferably, it is smooth as used for a photographic support. Raw base paper is preferred. As the pulp constituting the raw paper, one kind or a mixture of two or more kinds of natural pulp, recycled pulp, synthetic pulp and the like is used. This base paper has a sizing agent, a paper strengthening agent, a filler, an antistatic agent, an optical brightening agent, which is generally used in papermaking,
Additives such as dyes are blended. In addition, surface sizing agents,
A surface paper strength agent, a fluorescent whitening agent, an antistatic agent, a dye, an anchoring agent and the like may be applied on the surface.

The thickness of the base paper is not particularly limited, but it is preferable that the paper has good surface smoothness, such as being compressed by applying pressure with a calendar or the like during or after paper making, and the basis weight is 30. ˜250 g / m ² is preferred.

As the resin for the resin-coated paper, a polyolefin resin or a resin curable with an electron beam can be used.
The polyolefin resin is a homopolymer of olefins such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, and polypentene, or a copolymer of two or more olefins such as ethylene-propylene copolymer and a mixture thereof. Various densities and melt viscosity indexes (melt indexes) can be used alone or in combination.

In the resin of the resin-coated paper, white pigments such as titanium oxide, zinc oxide, talc and calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, stearic acid. Aluminum, fatty acid metal salts such as magnesium stearate, antioxidants such as Irganox 1010 and Irganox 1076, blue pigments and dyes such as cobalt blue, ultramarine blue, cesianian blue and phthalocyanine blue, cobalt violet, fast violet, manganese purple It is preferable to add various additives such as magenta pigments and dyes, fluorescent whitening agents, and ultraviolet absorbers in an appropriate combination.

The resin-coated paper, which is a support preferably used in the present invention, is produced by a so-called extrusion coating method in which a resin melted by heating is cast in the case of a polyolefin resin on a running base paper, and both sides of the resin are coated. Is covered by. In the case of a resin that is cured by an electron beam, the resin is applied by a commonly used coater such as a gravure coater or a blade coater, and then the resin is irradiated with an electron beam to cure and coat the resin. Further, it is preferable to perform activation treatment such as corona discharge treatment or flame treatment on the base paper before coating the base paper with the resin. The surface (surface) of the support to which the ink receiving layer is applied has a glossy surface, a matte surface or the like depending on the application, and the glossy surface is particularly predominantly used. It is not necessary to coat the back surface with a resin, but it is preferable to coat the resin from the viewpoint of preventing curling. The back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to activation treatment such as corona discharge treatment and flame treatment, if necessary. The thickness of the resin coating layer is not particularly limited, but it is generally coated on the surface or both front and back sides with a thickness of 5 to 50 μm.

Various back coat layers can be coated on the support in the present invention for the purpose of antistatic property, transport property, curl prevention property and the like. The back coat layer may contain an inorganic antistatic agent, an organic antistatic agent, a hydrophilic binder, a latex, a curing agent, a pigment, a surfactant and the like in an appropriate combination.

In the present invention, the coating method of the ink receiving layer is not particularly limited, and a known coating method can be used. For example, there are a slide lip method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method and the like.

In the present invention, the ink used for image recording is not particularly limited and may be so-called dye ink or pigment ink, but the image formed by the dye ink which is apt to cause discoloration and fading described above is not particularly limited. Treatment is preferred.

In the present invention, the ink jet recording material may be provided with an ink absorbing layer, an ink fixing layer, an intermediate layer, a protective layer and the like in addition to the layer containing at least one inorganic fine particle. For example, a water-soluble polymer layer may be applied as a lower layer, and a swelling layer or a porous layer may be applied as an upper layer. In particular, by providing a porous upper layer of alumina hydrate with a coating amount smaller than that of the vapor-phase-process silica of the lower layer, it is possible to obtain an ink jet recording material having high printing density and excellent storage stability.

[0051]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples. In addition, a part means a solid content weight part.

Example 1 A 1: 1 mixture of bleached hardwood kraft pulp (LBKP) and bleached softwood sulfite (NBSP) was beaten to a Canadian standard freeness of 300 ml to prepare a pulp slurry. Alkyl ketene dimer as a sizing agent to 0.5% by weight of pulp,
1.0% by weight of polyacrylamide to the pulp, 2.0% by weight of cationized starch to the pulp, and 0.5% by weight of polyamide epichlorohydrin resin to the pulp as a strength agent, and diluted with water to 1%. It was made into a slurry. This slurry was made into paper by a Fourdrinier paper machine so as to have a basis weight of 170 g / m ² , dried and conditioned to obtain a base paper for polyolefin resin-coated paper. A polyethylene resin composition in which 10% by weight of anatase-type titanium was uniformly dispersed in 100% by weight of a low-density polyethylene resin having a density of 0.918 g / cm ³ was melted at 320 ° C. to 200 m / 35 μm in thickness
Extrusion coating was carried out so as to be, and extrusion coating was carried out using a cooling roller having a finely roughened surface. On the other side, a blended resin composition of 70 parts by weight of a high density polyethylene resin having a density of 0.962 g / cm ³ and 30 parts by weight of a low density polyethylene resin having a density of 0.918 was similarly melted at 320 ° C. Extrusion coating to 30 μm,
It was extrusion coated using a roughened cooling roll.

After the high-frequency corona discharge treatment was applied to the surface of the above polyolefin resin-coated paper, the undercoat layer was coated with gelatin.
A support was prepared by coating and drying so as to give 0 mg / m ² .

An aqueous solution containing vapor phase silica and Charol DC902P was dispersed with a high pressure homogenizer, and polyvinyl alcohol or the like was added to prepare a coating liquid for the ink receiving layer having the following composition. 20 minutes
An inkjet recording sheet was prepared by coating and drying so that the coating amount was g / m ² . The film surface pH of the ink receiving layer was adjusted to 3.8.

<Ink Receptor Layer Composition> Gas phase method silica (average primary particle size 7 nm, specific surface area by BET method 300 m ² / g) 100 parts Dimethyldiallylammonium chloride polycondensate 3 parts (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) , Product name Charol DC902P) Polyvinyl alcohol 23 parts (Product name: PVA235, Kuraray Co., Ltd., saponification degree 88%, average degree of polymerization 3500) Boric acid 4 parts Amphoteric surfactant 0.3 parts (Product name: SWAM AM -2150, made by Nippon Surfactant)

After printing on the ink jet recording sheet prepared as described above by using an ink jet printer (PM-880C manufactured by Seiko Epson Corp.), polyvinyl alcohol having each of the following polymerization degrees (the saponification degree of each is about 88).
%) Overcoat liquid was applied with a wire bar and dried to obtain a test sample.

<Recording Sheet 1> No overcoat (blank).

<Recording sheet 2> Average degree of polymerization 500: Solid content 0.2 g / m ² (1 wt% aqueous solution was applied at 20 g / m ^{2; the same} applies to the following 0.2 g / m ² )

<Recording sheet 3> Average degree of polymerization 1000: solid content 0.2 g / m ²

<Recording sheet 4> Average degree of polymerization 2000: Solid content 0.2 g / m ²

<Recording sheet 5> Average degree of polymerization 2000: Solid content 0.4 g / m ² (2% by weight aqueous solution was applied at 20 g / m ² ;
The same applies to the following 0.4 g / m ² )

<Recording Sheet 6> Average Degree of Polymerization 2000: Solid Content 5.0 g / m ² (10 wt% Aqueous Solution 50 g / m ² Applied)

<Recording sheet 7> Average degree of polymerization 2200: Solid content 0.2 g / m ²

<Recording Sheet 8> Average Degree of Polymerization 2500: Solid Content 0.2 g / m ²

<Recording sheet 9> Average degree of polymerization 3000: solid content 0.1 g / m ² (0.5 wt% aqueous solution was applied at 20 g / m ^{2; the same} applies to the following 0.1 g / m ² )

<Recording sheet 10> Average degree of polymerization 3000:
Solid content 0.2 g / m ²

<Recording sheet 11> Average degree of polymerization 3500:
Solid content 0.1 g / m ²

<Recording sheet 12> Average degree of polymerization 3500:
Solid content 0.2 g / m ²

<Recording sheet 13> Average degree of polymerization 3500:
Solid content 0.4 g / m ²

<Recording sheet 14> Average degree of polymerization 3500:
Solid content 0.8 g / m ² (4 wt% aqueous solution applied at 20 g / m ² )

<Recording sheet 15> Average degree of polymerization 4000:
Solid content 0.1 g / m ²

<Recording sheet 16> Average degree of polymerization 4000:
Solid content 0.2 g / m ²

<Recording sheet 17> Average degree of polymerization 4500:
Solid content 0.1 g / m ²

Each of the obtained ink jet recording sheets was evaluated for storage stability (gas resistance) and glossiness as follows. The results are shown in Table 1.

<Gas resistance> For each of the CYMK inks, a cyan ink with the most gas fading was subjected to a forced test by exposure to ozone (20 ppm, 4 hours), and then an image of a reflection density of 1.0 part when fresh was obtained. The residual rate (concentration after exposure / concentration before exposure) was determined.

<Glossiness> The glossiness was measured according to the method described in JIS P-8142 (75-degree specular glossiness test method for paper and paperboard).

[0077]

[Table 1]

The glossiness of each recording sheet is 60 to 65.
%, The recording sheet 6 having a large amount of solid content and a large amount of coating liquid had a photo-like texture remarkably impaired due to glare and uneven gloss due to an excessive glossiness of the surface. For the other samples, no change in texture due to the application of the overcoat layer was observed.
As is clear from the above results, according to the preferred embodiment of the present invention, while maintaining a photo-like texture and gloss,
Image storability (gas resistance) is significantly improved.

Example 2 The vapor-phase-process silica used in Example 1 had an average primary particle size of 15 n.
The same test as in Example 1 was obtained except that the plate-like pseudo-boehmite having m and an aspect ratio of 5 was replaced.

Example 3 The same test as in Example 1 was carried out as a result of the same test as in Example 1 except that a polyester film was used as the support in Example 1.

[0081]

According to the present invention, an image forming method of a photo-like ink jet recording material can be obtained in which the photo-like texture and glossiness are maintained and the image storability (gas resistance) is improved.

Claims (8)

[Claims] 1. An inkjet recording method comprising forming an image on an inkjet recording material having at least one ink receiving layer on a support, and then overcoating the surface of the image with a solution of polyvinyl alcohol having a polymerization degree of 2100 or more. Image forming method of material. 2. The image forming method for an ink jet recording material according to claim 1, wherein the solid content coating amount of the polyvinyl alcohol is 0.05 g / m ² to ⁴ g / m ² . 3. The image forming method for an inkjet recording material according to claim 1, wherein the ink receiving layer contains inorganic fine particles. 4. The image forming method for an ink jet recording material according to claim 3, wherein the inorganic fine particles are fine particles of vapor-phase method silica or alumina having a primary particle diameter of 30 nm or less. 5. The image forming method for an ink jet recording material according to claim 1, wherein the ink receiving layer is crosslinked with a crosslinking agent. 6. The image forming method for an ink jet recording material according to claim 1, wherein the film surface pH is 3 to 6. 7. The image forming method for an ink jet recording material according to claim 1, wherein the ink receiving layer contains a cationic compound. 8. The support according to claim 1, which is a water-resistant support.
7. The image forming method for an inkjet recording material described in any one of 7.