JP2000351271A - Recording sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording sheet which shows a high quality/performance level in terms of ink absorption, anti-blocking properties, color reproducibility, recorded image, the water resistance, weatherability, transparency and surface gloss of a recorded image or recorded characters. SOLUTION: The recording sheet is constituted of a base material, an ink absorptive layer formed on at least one of the faces of the base material and a porous layer which is freely peelable from the ink absorptive layer, formed on the ink absorptive layer. The interlayer adhesive strength between the porous layer and the ink absorptive layer is 1-500 g/15 mm. The ink absorptive layer may contain at least either of a mold release agent or fine particles as a component and also may contain a crosslinking agent or a curing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a recording sheet and a method for manufacturing the same. More specifically, a recording sheet having excellent ink absorbency, blocking resistance, water resistance of a recorded image, weather resistance, color reproducibility, and excellent transparency, surface gloss, and clearness of a recorded image in an ink jet recording system, and It relates to the manufacturing method.

[0002]

2. Description of the Related Art Ink-jet recording systems have been rapidly spreading in recent years because they can be easily converted to full color, have low noise, have good printing quality, and are economical. Used in wide printers for sign displays. In inkjet recording, to prevent clogging of the ink jet nozzle,
Inks having low drying properties are required, and water-based inks are generally used mainly in view of safety and recording suitability. The ink is ejected from the ejection head toward the recording sheet as small droplets, and the recording sheet is required to quickly absorb the ink and record an image.

For example, in the case of a recording sheet having a low ink absorbency, the ink remains on the sheet surface without drying and fixing for a long time even after the recording is completed. When they are overlapped, the recording portion is stained with ink that has not been dried and fixed. In the high-density image area, a large amount of supplied ink is not absorbed,
The inks of the respective colors are mixed, and the quality of the recorded image or character deteriorates or flows out on the surface of the recording sheet.

Some proposals have been made to solve these problems. For example, JP-A-59-
174381 and JP-A-60-224578 propose to use a hydrophilic polymer such as starch, a water-soluble cellulose derivative, or polyvinyl alcohol as an ink receiving layer on a support. In a recording sheet, even if the ink absorbency is satisfied, the water resistance of the sheet itself is poor, and the ink receiving layer and the recording portion are dissolved in water, and blocking occurs when the sheets are superposed with a sticky surface.

Further, Japanese Patent Publication No. 3-72460 discloses that
There has been proposed a method comprising a combination of an ink-permeable surface layer and an ink-absorbing base layer, wherein the ink is absorbed by the base layer and blocking resistance is improved by the surface layer. However, since the ink passes through the surface layer and is absorbed by the underlayer, the ink penetrates deeply into the recording sheet, making it difficult to increase the color density of the recorded portion, and the underlayer also has poor water resistance. Low.

It has also been proposed to provide a porous layer as an ink absorbing layer to absorb ink by capillary action. For example, JP-A-58-11028 and JP-A-5-51470 disclose a method in which a porous layer having pores formed by agglomerating fine particles of silica and the like is formed on a support. A provided recording sheet has been proposed. These recording sheets have improved ink absorptivity, but have low transparency and low surface gloss due to light scattering of particles, and OHP (overhead projector) sheets requiring high transparency, photographs requiring high surface gloss, etc. Is not suitable for high-quality images. Japanese Patent Application Laid-Open No. 10-278417 proposes a recording sheet in which a porous layer is further provided on an ink absorbing layer provided on a support, and this recording sheet is also used for high-quality image applications. May not be enough.

Furthermore, Japanese Patent Application Laid-Open No. 61-86251 proposes a recording sheet in which a porous plastic thin film layer is laminated on an ink absorbing layer, but the porous plastic thin film is made of a hydrophobic material such as polyethylene or polypropylene. Because it is formed of plastic, ink permeability is not sufficient in ink jet recording in which water-based ink is mainly used, and because a porous plastic thin film is laminated by a thermocompression method, holes are crushed, Deform.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a recording sheet which is excellent in ink absorbency and blocking resistance, and which can greatly improve transparency, surface gloss and clearness of a recorded image, and production of the same. It is to provide a method.

Another object of the present invention is to provide a recording sheet having excellent water resistance, weather resistance and color reproducibility of a recorded image, and a method for producing the same.

Another object of the present invention is to provide a method for forming a recorded image which can greatly improve the sharpness and color reproducibility.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and have found that an ink absorbing layer is provided on a substrate, and a porous layer which can be peeled off from the ink absorbing layer. Provided that the transparency, surface gloss, clarity of a recorded image, and the like of the recording sheet can be significantly improved, and the present invention was completed.

That is, the recording sheet of the present invention comprises a base material, an ink absorbing layer on at least one side of the base material, and a porous layer formed on the ink absorbing layer. The porous layer can be peeled off. The interlayer adhesive strength between the porous layer and the ink absorbing layer is 1 to 500 g / 1.
It may be 5 mm. The ink absorbing layer may be made of a water-soluble polymer or a water-absorbing polymer, and the porous layer may be made of a hydrophilic polymer. The ink absorbing layer may be composed of a cross-linkable or curable water-soluble polymer or water-absorbing polymer, and may have a releasing property with respect to the porous layer. It may contain a curing agent and fine particles. The average pore size of the porous layer is 0.00
It may be about 5 to 10 μm. The thickness of the ink absorbing layer may be about 5 to 50 μm, the thickness of the porous layer may be about 1 to 100 μm, and the recording sheet has a light transmittance of 45% or more at a wavelength of 400 nm. There may be.

The present invention also includes a method for producing a recording sheet in which an ink-absorbing layer is formed on at least one surface of a base sheet, and a porous layer that can be peeled off from the ink-absorbing layer is formed. The ink absorbing layer can be formed using a coating solution containing a polymer and at least one of a release agent and fine particles, and the porous layer is a coating solution containing a polymer on the ink absorbing layer. And forming pores in the porous layer in a film forming step. The porous layer is
For example, a polymer, a good solvent for the polymer, and a poor solvent for the polymer and a coating solution composed of a solvent having a higher boiling point than the good solvent, the ink on the ink absorbing layer or other base material It may be applied and dried.

The present invention also relates to a method for forming a recorded image by recording an image on the porous layer of the recording sheet and then peeling the porous layer from the ink absorbing layer. After recording an image on the layer, a method of forming a recorded image in which the cover sheet is laminated and integrated on the porous layer and the cover sheet and the porous layer are separated from the ink absorbing layer is also included.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION [Porous layer] The average pore size on the surface and inside of the porous layer is about 0.005 to 10 µm, preferably about 0.01 to 8 µm, and more preferably about 0.08 µm.
It can be selected from a range of about 1 to 5 μm (for example, 0.01 to 3 μm). If the average pore size is less than 0.005 μm, the ink absorbability may be insufficient, and the average pore size may be 10 μm.
If it exceeds 300, water resistance and printing quality are likely to deteriorate.

The ink absorbency is also affected by the porosity of the porous layer. The porosity of the porous layer can be selected from the range of about 40 to 80%, preferably about 42 to 75%. If the porosity is less than 40%, the surface area of the absorbing surface is small, so that the absorption capacity of the film for ink is low, and if it exceeds 80%, the strength of the porous layer itself may be reduced.

The polymer constituting the porous layer is not particularly limited as long as a porous layer having high wettability with respect to ink can be formed, and various resins (thermoplastic resins and thermosetting resins) can be used. It can be used, and usually a thermoplastic resin is used. Examples of the thermoplastic resin include the following resins and polymers.

Cellulose-based resin (cellulose derivative): Cellulose ester [eg, organic acid esters such as cellulose acetate (cellulose acetate), cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate; cellulose nitrate , Inorganic acid esters such as cellulose sulfate and cellulose phosphate; mixed acid esters such as cellulose nitrate acetate, etc.] Cellulose ethers [eg, methyl cellulose, ethyl cellulose, isopropyl cellulose, butyl cellulose, benzyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, cyano] Ethyl cellulose, etc.]

Vinyl polymer: olefin polymer [for example, olefin homopolymer or copolymer (polyethylene, polypropylene, poly 1-butene, polyisobutene, polybutadiene, polyisoprene, polyarene, ethylene-propylene copolymer, etc.);
Copolymer of olefins and copolymerizable monomer (ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, modified polyolefin, etc.)] Halogen-containing vinyl polymer [for example, halogen-containing Vinyl monomer homo- or copolymer (polyvinyl chloride etc.), copolymer of halogen-containing vinyl monomer and copolymerizable monomer (vinyl chloride-vinyl acetate copolymer, vinylidene chloride-vinyl acetate copolymer) Polymer, vinylidene chloride- (meth) acrylic acid copolymer, vinylidene chloride- (meth) acrylic acid ester copolymer, etc.)] Vinyl ester-based polymer or a derivative thereof [eg, polyvinyl acetate, polyvinyl alcohol, ethylene- Vinyl alcohol copolymer, polyvinyl acetal polymer (polyvinyl formal, polyvinyl acetal) , Polyvinyl butyral, etc.)] Heterocyclic vinyl polymer [polyvinyl pyrrolidone, polyvinyl pyridine, etc.] Aromatic vinyl polymer [for example, styrene polymer (polystyrene, etc.), copolymerizable with aromatic vinyl monomer (Styrene- (meth) acrylic acid _C1-10 alkyl ester copolymer, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, etc.)] Allyl alcohol-based polymer (for example, , Allyl alcohol-C _1-6 alkyl vinyl ether copolymer) polyvinyl ketones [eg, polyvinyl methyl ketone, polyvinyl methyl isobutyl ketone, polymethyl isopropenyl ketone, etc.] vinyl ether polymers [eg, polymethyl vinyl ether, methyl vinyl ether- Maleic anhydride copolymer, etc.] (Meth) Holy or copolymer of a cryl polymer [eg, (meth) acrylic monomer ((meth) acrylonitrile, (meth) acrylate monomer, etc.), copolymerized with (meth) acrylic monomer Copolymers with functional monomers (vinyl monomers such as vinyl ester monomers, heterocyclic vinyl monomers, aromatic vinyl monomers, polymerizable unsaturated dicarboxylic acids or derivatives thereof) ]

Polysulfone-based polymer: a polymer having a bonding group —SO ₂ — in its molecule, such as polysulfone (eg, polyhexamethylene sulfone), sulfonated polysulfone, polyether sulfone, etc.

Polyester polymers: polyalkylene terephthalate (eg, homo- or copolyester containing 1,4-cyclohexane dimethylene terephthalate, ethylene terephthalate, butylene terephthalate, etc.), polyalkylene naphthalate (eg, ethylene naphthalate, butylene Homo or copolyester containing naphthalate)

Polyamide-based polymer: aliphatic polyamide (for example, nylon 6, nylon 6
6, nylon 610, nylon 612, nylon 11,
Nylon 12 etc.)

Polycarbonate polymer: A polymer obtained by reacting a dihydroxy compound such as 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) with a diester carbonate such as phosgene or dimethyl carbonate.

Polyurethane-based polymer: a polymer obtained by reacting a polyol with a polyisocyanate such as polyethylene glycol such as tolylene diisocyanate and a polyol.

Polymers derived from epoxides: polyalkylene glycol (for example, polyethylene glycol or polypropylene glycol) or epoxy resin (for example, ether-based epoxy resin such as bisphenol-type epoxy resin or novolak-type epoxy resin, amine-based epoxy resin) These polymers can be used alone or in combination of two or more.

The polymer constituting the porous layer is not particularly limited as long as it has high ink wettability on the layer surface and the surface of the pores, and may be appropriately selected depending on the type of the target ink. However, generally used inks are often water-based inks, and in that case, among the above polymers, hydrophilic polymers are particularly preferred. The hydrophilic polymer has a contact angle with water of less than 80 ° (preferably 0 °).
~ 60 °, especially about 0-40 °).
The contact angle, when a water drop is placed on the surface of the polymer at room temperature,
At the intersection of the surface of the water droplet and the surface of the polymer when the spread of the water droplet has stopped, the angle on the water droplet side among the angles between the tangent to the water droplet and the surface of the polymer.

Examples of such a hydrophilic polymer include cellulose derivatives (eg, cellulose esters such as cellulose acetate, cellulose propionate and cellulose nitrate, and cellulose ethers such as ethyl cellulose).
Polyamide, (meth) acrylic polymer [for example, poly (meth) acrylate such as polymethyl methacrylate, polyacrylonitrile, polyacrylamide, poly-N-methylacrylamide, etc.], polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine,
Polysulfone-based polymers (eg, polysulfone, polyethersulfone, etc.), vinyl ether-based polymers (eg, polymethyl vinyl ether, methyl vinyl ether-maleic anhydride copolymer, etc.), vinyl acetate-based polymers or derivatives thereof (eg, Vinyl acetate and its partially saponified product, polyvinyl alcohol, ethylene-vinyl acetate copolymer and its partially saponified product), and styrene-maleic anhydride copolymer. Of these, cellulose acetate (cellulose diacetate, cellulose triacetate, etc.) is particularly preferred.

Polytetrafluoroethylene, polyethylene, polystyrene and the like, even if they are hydrophobic polymers in the above definition, can be added to the surface by a method such as adding a surfactant, a wetting agent, coating, or plasma treatment. By imparting hydrophilicity, it is included in the hydrophilic polymer of the present invention.

The thickness of the porous layer is not particularly limited and can be selected according to the application. For example, it can be selected from a range of about 1 to 100 μm, preferably about 3 to 50 μm (eg, 5 to 30 μm). When the thickness of the porous layer is less than 1 μm, the water resistance is insufficient, and when it exceeds 100 μm, there is a possibility that the transparency is reduced or the ink absorbency is reduced.

[Ink Absorbing Layer] The ink absorbing layer can be composed of a substance capable of absorbing ink or a solvent component of the ink.
There is no particular limitation, and the same resin as the porous layer can be used. In the ink jet recording method, since an aqueous ink is frequently used, the ink absorbing layer is usually formed of a water-soluble polymer or a polymer compound having water absorbability even when insoluble in water (hereinafter, referred to as “hydrophilic polymer”). ).

Examples of the hydrophilic polymer include the following resins or polymers.

Vinyl ester polymer: vinyl acetate polymer (for example, polyvinyl acetate, vinyl acetate-methyl acrylate copolymer, etc.), vinyl alcohol polymer (for example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer) Union, etc.), polyvinyl acetal-based polymers (eg, polyvinyl formal, polyvinyl acetal, polyvinyl butyral, etc.)

Hydrophilic natural polymers or derivatives thereof: starch, corn starch, sodium alginate, gum arabic, gelatin, casein, dextrin, etc.

Cellulose derivatives: Cellulose ethers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose and cyanoethylcellulose, and cellulose esters such as cellulose acetate, cellulose propionate and cellulose sulfate.

Polyalkylene oxide: polyethylene oxide, ethylene oxide-propylene oxide block copolymer, etc.

Polymer having a carboxyl group or a sulfonic acid group or a salt thereof: Acrylic polymer [for example, poly (meth) acrylic acid or a salt thereof (alkali metal salt such as ammonium or sodium), methyl (meth) acrylate -(Meth) acrylic acid copolymer, (meth) acrylic acid-vinyl alcohol copolymer, etc.] Vinyl ether polymers (for example, polyvinyl alkyl ether such as polyvinyl methyl ether and polyvinyl isobutyl ether, methyl vinyl ether-maleic anhydride copolymer) Styrene-based polymer (for example, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, sodium polystyrene sulfonate, etc.)

Polysulfone-based polymers: Polymers having a bonding group —SO ₂ — in the molecule thereof, such as polysulfone (eg, polyhexamethylene sulfone), sulfonated polysulfone (eg, sodium polyvinyl sulfonate), polyether sulfone, etc.

Nitrogen-containing polymer (or cationic polymer) or a salt thereof: quaternary ammonium salt (eg, polyvinylbenzyltrimethylammonium chloride, polydiallyldimethylammonium chloride, etc.), polydimethylaminoethyl (meth) acrylate hydrochloride, polyvinyl Pyridine, polyvinyl imidazole, polyethylene imine, polyamide polyamine, polyacrylamide, polyvinyl pyrrolidone, etc. These hydrophilic polymers can be used alone or in combination of two or more.

Among these hydrophilic polymers, cellulose derivatives (particularly cellulose esters such as hydroxyethyl cellulose), vinyl ester polymers (particularly vinyl acetate polymers such as vinyl acetate-methyl acrylate),
Vinyl alcohol-based polymers such as polyvinyl alcohol, etc.), nitrogen-containing polymers (especially, polyvinylpyrrolidone, etc.) are preferred, and vinyl ester-based polymers, particularly vinyl acetate-based polymers, are particularly preferred.

The vinyl acetate polymer can be composed of a copolymer of vinyl acetate and a monomer copolymerizable therewith, and includes partially or completely saponified products thereof. Monomers copolymerizable with vinyl acetate include olefins (for example,
Ethylene, propylene, butadiene, etc.), (meth) acrylic acid or a salt thereof [for example, (meth) acrylic acid,
Sodium (meth) acrylate], alkyl (meth)
Acrylate [e.g., methyl (meth) acrylate or the like], hydroxyl group-containing (meth) acrylate [e.g., 2-hydroxyethyl (meth) acrylate or the like], amino group-containing (meth) acrylate [e.g.
N, N-diethylaminoethyl (meth) acrylate, etc.), epoxy group-containing (meth) acrylate [for example,
Glycidyl (meth) acrylate, etc.), amide group-containing monomer [eg, (meth) acrylamide, etc.], epoxy group-containing monomer [eg, allyl glycidyl ether, etc.], monomer containing sulfonic acid group or salt thereof [eg, styrene sulfone] Acid and its sodium salt], a monomer containing a carboxyl group or a salt thereof [for example, crotonic acid and its sodium salt, alkyl maleic acid monoester, etc.], and a monomer containing an acid anhydride [for example, maleic anhydride and the like] And monomers containing a vinyl group [eg, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl trisalkoxysilane, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, etc.].

The ink absorbing layer may be made of a crosslinkable or curable hydrophilic polymer to impart water resistance. The crosslinkable or curable hydrophilic polymer is a polymer capable of self-crosslinking the hydrophilic polymer itself (eg, a methylol group, an alkoxysilyl group-containing hydrophilic polymer, an acetoacetyl group-modified hydrophilic polymer described below, and the like). Or a cross-linking system in which a hydrophilic polymer is provided with a cross-linking property by adding a cross-linking agent or a curing agent.

The polymers constituting the crosslinking system include (1)
A polyoxyalkylene unit or a hydroxyl group,
(2) acetoacetyl group, (3) carboxyl group,
A hydrophilic polymer having at least one functional group selected from (4) an acid anhydride group and (5) an amino group is preferably used.

(1) Examples of the hydrophilic polymer having a polyoxyalkylene unit or a hydroxyl group include vinyl ester-based polymers (eg, a polyoxyalkylene-vinyl acetate copolymer having a hydrophilic group such as an ether group) and the like. Saponified products (polyvinyl alcohol) and the like can be used.

(2) The acetoacetyl group-modified hydrophilic polymer includes an acetoacetyl group-containing hydrophilic polymer formed by a reaction between a hydroxyl group-containing hydrophilic polymer and an acetoacetate ester, for example, an acetoacetyl group-modified hydrophilic polymer. Vinyl acetate-based copolymers (acetoacetyl group-containing polyvinyl alcohol, acetoacetyl group-containing cellulose derivatives, etc.) are included.

(3) The carboxyl group-modified hydrophilic polymer includes (3a) a carboxyl group-modified vinyl ester polymer, for example, a vinyl ester (eg, vinyl acetate) and a carboxyl group-containing unsaturated monomer ((meth) Monocarboxylic acids such as acrylic acid, dicarboxylic acids such as maleic acid, and acid anhydrides or monoalkyl esters thereof)
And a saponified product thereof (carboxyl group-modified polyvinyl alcohol) such as a vinyl acetate- (meth) acrylic acid copolymer or a saponified product thereof (3
b) carboxyl group-containing polysaccharides such as carboxy C
_1-4 alkyl cellulose, carboxymethyl dextran and the like.

(4) Acid anhydride group-containing hydrophilic polymers include:
Alkyl vinyl ether-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, (meth) acrylic ester-maleic anhydride copolymer and the like are included.

(5) Amino group-containing hydrophilic polymers include polyamide-polyamine, polyvinylamine, and poly (N-
Vinyl hydroformamide), amino group-containing polysaccharides and the like.

The crosslinking agent or curing agent is not particularly limited as long as it can crosslink the hydrophilic polymer, and can be selected according to the type of the hydrophilic polymer. For example, as a crosslinking agent or a curing agent, an organic crosslinking agent [a compound having a carboxyl group or an acid anhydride group (such as a polyvalent carboxylic acid or an acid anhydride thereof), a compound having an aldehyde group (glyoxal, malondialdehyde, Compounds having a plurality of aldehyde groups such as glutaraldehyde, terephthalaldehyde, dialdehyde starch, acrolein copolymerized acrylic resin, etc., compounds having an epoxy group (alkylene glycol diglycidyl ether, polyoxyalkylene glycol diglycidyl ether, neopentyl glycol) Compounds having a plurality of epoxy groups such as diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, 1,3,3-diepoxybutane, etc.), containing nitrogen Compounds (amino resins such as urea resin, guanamine resin and melamine resin; aliphatic, alicyclic and aromatic such as ethylenediamine, hexamethylenediamine, polyoxyalkylene-type diamine or polyamine (that is, polyether-type diamine or polyamine)) Diamine or polyamine, etc.),
Inorganic compounds such as compounds having a methylol group or an alkoxymethyl group (for example, a polymer having an N-methylol (meth) acrylamide group), compounds having an isocyanate group (such as polyisocyanate and block-type polyisocyanate), and metal compounds Crosslinking agents [boric acid or borate (such as borax), zirconium compounds (eg,
Halides, salts with inorganic acids such as sulfuric acid and organic acids such as acetic acid), titanium compounds (eg, alkoxides such as tetraethoxytitanate), aluminum compounds (eg, alkoxides such as trimethoxyaluminate), phosphorus compounds (For example, phosphites,
Bisphenol A-modified polyphosphoric acid, etc.), silane coupling agents (silicone compounds having a reactive functional group such as an alkoxyl group or a glycidyl group), etc.].
These crosslinking agents or curing agents can be used alone or in combination of two or more. Among these crosslinking agents or curing agents, polyvalent carboxylic acids or acid anhydrides thereof, metal compounds and the like are preferable.

When the ink absorbing layer contains a hydroxyl group-containing hydrophilic polymer, a polyvalent carboxylic acid or a salt thereof,
Alternatively, when combined with an anhydride of a polycarboxylic acid, the ink absorbency, antiblocking property, image clarity (print quality) and water resistance can be improved.

Examples of the polyvalent carboxylic acid include aliphatic polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid and sebacic acid.
_2-10 fatty acid saturated polycarboxylic acid, etc., fumaric acid, maleic acid, maleic anhydride, itaconic acid, etc., C _4-6 aliphatic unsaturated polycarboxylic acid, etc.), alicyclic polycarboxylic acid (1,4-cyclohexane) _C8-10 alicyclic polycarboxylic acids such as dicarboxylic acid and tetrahydrophthalic acid, etc., and aromatic polycarboxylic acids (C such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, etc.) _8-12 aromatic polycarboxylic acids or acid anhydrides thereof), oxypolycarboxylic acids (such as malic acid, tartaric acid, and C _3-6 oxypolycarboxylic acids such as citric acid), and heterocyclic polycarboxylic acids ( Pyridinecarboxylic acid, pyridinetricarboxylic acid, pyridinetetracarboxylic acid, etc.).

More preferred polycarboxylic acids are often water-soluble or water-dispersible, and at a temperature of 30 ° C., 5 g or more (preferably 10 g or more) per 100 g of water.
(More preferably 30 g or more). Such polycarboxylic acids include C _2-6
Aliphatic polycarboxylic acids (especially C _3-5 aliphatic polycarboxylic acids such as maleic acid or maleic anhydride) and the like are included.

The polycarboxylic acid may be used as a salt, and a part or all of the carboxyl group of the polycarboxylic acid may form a salt with a base. The polycarboxylic acid includes a salt with an inorganic base (eg, an alkali metal such as ammonia, potassium, and sodium) and a salt with an organic base (eg, a tertiary amine).

A curing catalyst or a curing accelerator may be added to the ink absorbing layer in order to promote a curing reaction. As the curing catalyst or the curing accelerator, for example, an acid, an alkali, an organic tin compound, an organic aluminum compound, an organic titanium compound, an organic zirconium compound, an acidic compound, an acidic phosphoric acid, depending on the type of the hydrophilic polymer and the crosslinking mechanism. Esters, mixtures or reactants of the acidic phosphate esters and amines. These curing catalysts or curing accelerators can be used alone or in combination of two or more.

The amount of the crosslinking agent or curing agent used is, for example,
In terms of solid content, 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the polymer constituting the ink absorbing layer.
It is about 0.1 parts by weight (for example, 0.1 to 18 parts by weight, preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight).

In order to facilitate separation of the ink absorbing layer and the porous layer, the ink absorbing layer may have releasability from the porous layer. Further, in order to improve the releasability of the ink absorbing layer, a release agent may be added to the ink absorbing layer.

Examples of the releasing agent include silicone compounds (for example, silicone oil, silicone resin, polyorganosiloxane having a polyoxyalkylene unit, etc.),
Higher fatty acids or salts thereof, higher fatty acid esters, waxes (eg, vegetable waxes such as carnauba wax, animal waxes such as wool wax, paraffins such as paraffin wax, polyethylene wax, etc.), fluorine-containing compounds (eg, fluorine oil) , Polytetrafluoroethylene, etc.). These release agents may be used in the form of an emulsion. These release agents can be used alone or in combination of two or more.

The amount of the release agent used is, for example, in terms of solid content, 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the polymer constituting the ink absorbing layer. For example, it is about 0.1 to 2).

Further, in order to improve the releasability of the ink absorbing layer, fine particles may be contained in the ink absorbing layer. Examples of fine particles include inorganic fine particles (white carbon, calcium silicate, aluminum silicate, magnesium silicate, zeolite, amino magnesium silicate, diatomaceous earth, calcined siliceous earth, magnesium carbonate, alumina, silica, talc, kaolin, delamikaolin, clay , Zinc oxide, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, calcium sulfate, barium sulfate, mineral particles such as sericite, bentonite, smectite, etc.) , Organic fine particles (polystyrene resin, acrylic resin, urea resin, melamine resin,
Crosslinked or non-crosslinked organic fine particles such as benzoguanamine resin, and organic fine particles such as fine hollow particles. These fine particles can be used alone or in combination of two or more. The average particle size of the fine particles is about 1 to 30 μm, preferably about 2 to 25 μm (for example, 2 to 20 μm), and usually about 5 to 25 μm (for example, 10 to 25 μm).

The amount of the fine particles to be used is, for example, 0.05 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.1 to 5 parts by weight, in terms of solid content, based on 100 parts by weight of the polymer constituting the ink absorbing layer. Is about 0.15 to 3 parts by weight.

In the present invention, the porous layer and the ink-absorbing layer are peelable, and the interlayer adhesion strength between the porous layer and the ink-absorbing layer is appropriately selected depending on the application.
About 15 mm (for example, 2 to 500 g / 15 mm), preferably 1 to 200 g / 15 mm (for example, 7 to 200 g / 15 mm)
g / 15 mm), more preferably 2-150 g /
It is about 15 mm (for example, 2 to 140 g / 15 mm), and usually 3 to 100 g / 15 mm (for example, 10 to 6 g).
0 g / 15 mm).

Further, in the present invention, in the recording sheet after image formation, the interlayer adhesion strength between the porous layer and the ink absorbing layer in the non-image area is defined as Fn, and the adhesion between the porous layer and the ink absorbing layer in the image area is defined as Fn. When the interlayer adhesion strength is Fp,
The following formula (1) may be satisfied, preferably the following formula (2), and more preferably the following formula (3). The conditions for forming the image area are the same as the conditions in the ink absorbency test in Examples described later.

| Fp-Fn | <150 g / 15 mm (1) | Fp-Fn | <120 g / 15 mm (2) | Fp-Fn | <90 g / 15 mm (3)

The thickness of the ink-absorbing layer can be selected according to the application, for example, about 5 to 50 μm, preferably 10 to 3 μm.
It can be selected from a range of about 0 μm. If the thickness of the ink absorbing layer is less than 5 μm, the ink may not be sufficiently absorbed, and if it exceeds 50 μm, the transparency may be reduced or the recording sheet may be curled.

Further, the porous layer and / or the ink absorbing layer may contain conventional additives such as a defoaming agent, a coating improver,
Contains thickeners, lubricants, stabilizers (antioxidants, UV absorbers, heat stabilizers, light stabilizers, etc.), dyes, pigments, antistatic agents, antiblocking agents, fillers, gelling agents, etc. Is also good. Further, the porous layer may include a crosslinking agent or a curing agent.

[Substrate] The material of the substrate is not particularly limited, and examples thereof include paper, coated paper, nonwoven fabric, and a plastic film or sheet. From the viewpoints of transparency, strength, and practical use, a plastic film is used. Alternatively, a sheet can be preferably used.

Examples of the polymer constituting the plastic film or sheet include an olefin polymer (eg, polypropylene) and a halogen polymer (eg, polypropylene).
Polyvinyl chloride), styrene-based resin (eg, polystyrene, rubber-reinforced polystyrene, ABS resin, etc.), cellulose-based resin (cellulose derivative) (eg, cellulose acetate, etc.), polyester-based resin (eg,
Examples thereof include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc.), polycarbonate resins (eg, bisphenol A type polycarbonate), polyamide resins (eg, aliphatic polyamides such as nylon 6). Further, if there is no problem in transparency, these copolymers, blends and cross-linked products can also be used. Of these, from the viewpoint of mechanical strength, workability, etc.,
Polyester resins, especially polyalkylene arylate resins such as polyethylene terephthalate can be preferably used. These resins can be used alone or in combination of two or more as a single-layer film or a laminated film.

If necessary, an antioxidant, a heat stabilizer, a lubricant, a pigment, an ultraviolet absorber and the like may be added to the plastic film or sheet. Further, in order to improve the adhesiveness with the ink absorbing layer, a corona discharge treatment, an undercoat treatment, or the like can be performed.

The thickness of the substrate is, for example, about 20 to 200 μm, preferably 50 to 170 μm in consideration of the fact that an image is formed by inserting it into an ink jet printer.
It is about μm, more preferably about 80 to 150 μm. [Manufacturing method] In the recording sheet of the present invention, an ink absorbing layer is formed on at least one side of a base sheet, and a porous layer which is peelable from the ink absorbing layer is formed on the ink absorbing layer. It can be manufactured by the following.

The ink absorbing layer can be manufactured by a conventional method. That is, it can be formed by a method such as applying a coating liquid containing the constituent components of the ink absorbing layer on a base material and drying. The application method is not particularly limited, and a known method such as a roll coating, an air knife coating, a blade coating, a rod coating, a bar coating, and a comma coating method can be applied. The solvent of the coating solution can be selected according to the type of the hydrophilic polymer and the like, and is not particularly limited.

The porous layer is formed by a phase separation method in which a polymer is subjected to microphase separation using a good solvent and a poor solvent, a foaming method in which a polymer is foamed to form pores, and a stretching method in which a polymer film is stretched. A radiation irradiation method of irradiating a polymer film with radiation to form pores, from a film composed of a polymer or an inorganic salt soluble in a solvent and a polymer insoluble in the solvent, a component soluble in the solvent. It can be produced by an extraction method in which pores are formed by extraction and removal, or a sintering method in which polymer particles are partially fused or solidified with a binder or the like and pores between particles are used as pores.

Among these methods, a phase separation method in which a polymer is microphase-separated using a good solvent and a poor solvent is preferably used. Examples of the microlayer separation method include a dry phase conversion method (mainly a polymer). A method of obtaining a porous layer by applying a coating solution comprising a good solvent for the polymer and a poor solvent for the polymer and a solvent having a higher boiling point than the good solvent, followed by drying). A wet phase inversion method (cast or coated with a coating solution containing at least a good solvent for the polymer, immersed in a poor solvent for the polymer,
A method of forming a porous layer by causing phase separation), but the dry phase inversion method is particularly preferably used because it is excellent in mass productivity.

The method for producing the porous layer by the dry phase inversion method is described in more detail below. A polymer, a good solvent for this polymer, and a poor solvent for this polymer, and a coating solution composed of a solvent having a higher boiling point than the good solvent is applied on a substrate, and the boiling point is obtained by drying. The good solvent with the lowest evaporates first. At that time, as the evaporation of the good solvent progresses, the solubility of the polymer decreases, and the polymer forms micelles and undergoes phase separation with the poor solvent phase. Furthermore, as the poor solvent evaporates, the micelles come into contact with each other to form a network structure,
Upon completion of the evaporation of the poor solvent, a porous layer is formed.

The good solvent can be selected according to the kind of the polymer, for example, ketones (C _3-6 dialkyl ketone such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, cyclohexanone, etc.) , Esters (C _1-4 alkyl formate such as ethyl formate, methyl acetate, ethyl acetate,
Acetic acid C _1-4 alkyl ester such as butyl acetate, ethyl propionate, ethyl lactate, etc., ethers (1,4-dioxane, tetrahydrofuran, tetrahydropyran,
Cyclic or chain C _4-6 ethers such as diethyl ether, diisopropyl ether and dimethoxyethane), cellosolves (C _1-4 alkyllosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve), cellosolve acetates (methyl cellosolve acetate, C _1-4 alkyl cellosolve acetates such as ethyl cellosolve acetate), aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated hydrocarbons (methylene chloride, ethylene chloride, etc.), amides (formamide, acetamide, N -Methylformamide, N-methylacetamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc., sulfoxides (dimethylsulfoxide, etc.), nitriles (acetonitrile, propionitrile, butyronitrile, Nzonitoriru etc.), organic acids (formic acid, acetic acid, propionic acid), organic acid anhydrides (maleic anhydride, acetic anhydride, etc.), and mixtures thereof and the like. In addition, a good solvent [for example, lower alcohols (C _1-4 alkyl alcohol such as methanol, ethanol, isopropanol, butanol, diacetone alcohol, etc.), cycloalkanol (cyclopentanol, cyclohexanol, methylcyclohexanol,
C _4-8 cycloalkanol optionally substituted by a C _1-4 alkyl group such as dimethylcyclohexanol)
Depending on the type of resin, it may be a poor solvent. The good solvent may include a nitro compound (nitromethane, nitroethane, nitropropane, etc.) and the like.

More specifically, when cellulose acetate is used as the polymer, preferred good solvents include acetone, methyl ethyl ketone, ethyl acetate, dioxane, dimethoxyethane, methyl cellosolve, methyl cellosolve acetate, and mixtures thereof, especially acetone. Is preferred.

The poor solvent means a solvent having no solubility or low solubility in the polymer to be used. The type of the poor solvent is not particularly limited as long as it has a higher boiling point than the above-mentioned good solvent. Examples of the poor solvent include water, esters (C _5-8 alkyl formate such as amyl formate and isoamyl formate, amyl acetate, hexyl acetate, octyl acetate, acetic acid 3).
C such as -methoxybutyl, 3-ethoxybutyl acetate, butyl propionate, 3-methoxybutyl propionate, etc.
_C2-4 aliphatic carboxylic acids _C6-10 alkyl esters which may have _1-4 alkoxyl groups, benzoic acid _C1-4 alkyl esters such as methyl benzoate, ethyl benzoate and propyl benzoate), Examples include alcohols (C _6-10 alcohols such as amyl alcohol, heterocyclic alcohols, etc.), aliphatic polyhydric alcohols (ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerin, etc.), and mixtures thereof. it can.

More specifically, when cellulose acetate is used as the polymer, preferred poor solvents include amyl formate and
Preference is given to cyclohexanol, methylcyclohexanol, ethyl benzoate or mixtures thereof, especially cyclohexanol.

The ratio between the good solvent and the poor solvent in the coating solution is not particularly limited as long as a uniform solution of the polymer can be formed, and may be appropriately selected depending on the desired porosity of the porous layer. Usually, 100 parts by weight of good solvent and 0 part of poor solvent
About 300 parts by weight, preferably about 3 to 250 parts by weight, more preferably about 5 to 250 parts by weight.

The content of the polymer in the coating solution can be selected according to the degree of polymerization of the polymer, for example, 1 to 30% by weight,
Preferably, it can be selected from the range of about 1 to 25% by weight, particularly about 3 to 20% by weight (for example, 3 to 15% by weight).

In the coating solution, conventional additives such as an antifoaming agent, a coating improver, and the like can be used as long as the properties of the present invention are not impaired.
Thickener, heat stabilizer, lubricant, UV absorber, antistatic agent,
An anti-blocking agent or the like may be added.

The mixing of the polymer, good solvent and poor solvent can be carried out by a conventional method such as adding the polymer to a good solvent, dissolving the polymer, adding a poor solvent and stirring and mixing. .

The method for applying the porous layer is not particularly limited.
Known methods such as roll coating, air knife coating, blade coating, rod coating, bar coating, and comma coating can be applied.

The method for drying the porous layer is not particularly limited.
When the dry phase inversion method is used, first, the good solvent evaporates to form micelles of the polymer, and then the micelles of the polymer come into contact with each other due to the evaporation of the poor solvent to form a network structure. , It is necessary to control the vapor pressure and the like.

In the recording sheet of the present invention, the ink absorbing layer and the porous layer may be formed on only one side of the substrate, or may be formed on both sides. For the formation of the porous layer, a coating solution containing a polymer is applied on the ink absorbing layer,
The pores of the porous layer may be formed in the film forming step, or a porous layer separately prepared by, for example, a dry phase inversion method may be laminated on the ink absorbing layer.

When using a transparent substrate, the recording sheet of the present invention is preferably transparent to visible light. For example, the light transmittance at a wavelength of 400 nm is 45% or more (that is, 45 to 100). %), Preferably 60 to 100
% (For example, 70 to 100%). An opaque substrate may be used depending on the application.

The recording sheet thus obtained is
After the ink arrived at the surface of the recording sheet, the ink was quickly absorbed by the porous layer, and then the solvent component of the ink was reliably absorbed and held by the ink absorbing layer, so that the ink was tacky on the surface of the recording sheet for a long time. As it does not remain, ink does not flow or mix, and a good image can be recorded.

In the present invention, after an image or a character is recorded on the porous layer of the recording sheet, the recorded image can be formed by peeling the porous layer from the ink absorbing layer. In the recording image forming method of the present invention, since the porous layer can be peeled off from the ink absorbing layer, the sharpness, color reproducibility and transparency of the image formed on the ink absorbing layer can be improved by peeling the porous layer. Can be improved.

After an image or text is recorded on the porous layer of the recording sheet, a cover sheet is laminated on the porous layer and integrated, and the cover sheet and the porous layer are separated from the ink absorbing layer. To form a recorded image. As the cover sheet, the above-mentioned substrate film, particularly, a transparent film can be used. In the method for forming a recorded image of the present invention, the porous layer can be peeled off from the ink absorbing layer, so that the porous layer can be transferred or transferred smoothly. In particular, a sheet having a small difference in interlayer adhesive strength between an image portion and a non-image portion has excellent peeling workability. Also, peeling the porous layer from the relatively water-resistant ink absorbing layer,
When used together with the cover sheet (for example, a cover sheet having a porous layer is adhered with the porous layer inside), it is also suitable for outdoor use where demands on water resistance are severe.

The recording sheet of the present invention is useful as an ink jet recording sheet for recording by discharging small droplets of ink, but is particularly useful for an OHP sheet or a high-quality image requiring transparency and surface gloss. Useful for sheets.

[0089]

According to the present invention, a recording sheet having excellent ink absorbency, blocking resistance, color reproducibility, water resistance and weather resistance of a recorded image or character, and having transparency and surface gloss can be produced.

[0090]

The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0091] Unless otherwise specified, parts or%
Is based on weight. The recording sheets obtained in Examples and Comparative Examples were evaluated for light transmittance, ink absorption, water resistance, image resolution, blocking resistance, and interlayer adhesive strength as follows.

[Light Transmittance] The light transmittance of the recording sheet obtained in Example 1 was measured at a wavelength of 400 nm using a spectrophotometer U-3300 (manufactured by Hitachi, Ltd.).

[Ink Absorption] Ink jet printer (MasterJet-JC20, manufactured by Graphtec)
08), the pigment-type aqueous inks (cyan, yellow, and yellow) were added to the recording sheets obtained in Examples and Comparative Examples.
Magenta) was printed solid to form a recorded image. After printing, place a copy paper for PPC on the print unit at regular intervals, and apply a load of 250 g /
After applying cm ² for 10 seconds, the copy paper was peeled off, the degree of ink set-off was visually determined, and the time until set-off was no longer observed.

[Water Resistance-1] The same printing as in the ink absorption test was performed on the recording sheets obtained in Examples and Comparative Examples.
The printed area was wiped three times with a cotton swab sufficiently containing water at 25 ° C., and the adhesion of the ink to the cotton swab was visually evaluated according to the following criteria.

◎: No sticking to cotton swabs 少 し: Slight ink sticking to cotton swabs, thinning printed portion ×: Completely peeling off coating layer of wiped portion

[Water resistance-2] The same printing as in the ink absorption test was performed on the recording sheet obtained in the example, and the recording sheet was immersed in water at normal temperature for 24 hours, and the appearance was visually evaluated according to the following criteria.

：: No abnormality Δ: Slight elution of the image part ×: Most of the image part eluted

[Image Resolution] Inkjet printer (MasterJet-JC20, manufactured by Graphtec)
08), a yellow-based magenta line (width 100 mm) was added to the recording sheets obtained in Examples and Comparative Examples.
μm) was printed, and the dots were observed with a microscope at a magnification of 50 times, and evaluated according to the following criteria.

◎: Little bleeding around the dot ○: Little bleeding around the dot, measured value is 120
Exceeding μm ×: Bleeding around dots, and the boundary between adjacent yellow and magenta dots is unclear

[Blocking Resistance] Two or more recording sheets obtained in Examples and Comparative Examples were stacked, and 4
It was stored under a load of 0 g / cm ² at 40 ° C. and 90% RH for one day, and evaluated according to the following criteria.

A: Neither matting nor blocking O: Matting but no blocking ×: Blocking

[Interlayer adhesion strength] A cellophane tape was stuck to the surface of the porous layer of the recording sheet obtained in each of the examples and comparative examples, a sample was cut out to a width of 15 mm, and a tensile tester Orientec Co., Ltd. Tensilon UCT- The peel strength was measured at 200 mm / min using 5T.

Example 1 A 15% aqueous solution 100 of a modified polyvinyl alcohol (OKS-7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was placed on a 100 μm-thick polyethylene terephthalate film (Melinex 339, manufactured by DuPont Japan) which had been subjected to an easy adhesion treatment.
1.5 parts of maleic acid and 0.1 part of a silicone release agent.
The coating solution containing 02 parts was applied and dried at 120 ° C. for 5 minutes to form an ink absorbing layer having a thickness of 15 μm. Further, cellulose acetate (average acetylation degree 55, viscosity average polymerization degree 170) was further formed thereon. A dope obtained by adding 100 parts of cyclohexanol to 100 parts of an acetone solution having a content of 10% is applied.
Drying was performed for 3 minutes in an atmosphere of 80 ° C. and 90% RH to form a porous layer having a thickness of 8 μm in which pores having an average pore diameter of 0.9 μm were present at high density. The light transmittance of the obtained recording sheet was 70%, indicating good transparency. Table 1 shows other evaluation results of the recording sheet.

Example 2 100 parts of a 15% aqueous solution of polyvinyl alcohol or a derivative thereof (Kuraray Co., Ltd., PVA217) was coated on a 100 μm-thick polyethylene terephthalate film (Melinex 705, manufactured by DuPont Japan) which had been subjected to an easy adhesion treatment. 1.5 parts of acid, 0.0 part of silicone release agent
The coating solution to which 2 parts were added was applied and dried at 120 ° C. for 5 minutes to form an ink absorbing layer having a thickness of 15 μm. Further, cellulose acetate (average acetylation degree 55, viscosity average polymerization degree 170) was further formed thereon. A dope obtained by adding 100 parts of cyclohexanol to 100 parts of a 10% solution of acetone at 80 ° C.
Drying was performed for 3 minutes in an atmosphere of 90% RH to form a porous layer having a thickness of 8 μm in which pores having an average pore diameter of 0.9 μm were present at high density. Table 1 shows the evaluation results of the recording sheet.

Example 3 A 15% aqueous solution of a modified polyvinyl alcohol (OKS-7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied to a 100 μm-thick polyethylene terephthalate film (Melinex 705, manufactured by DuPont Japan) which had been subjected to an easy adhesion treatment.
Parts by weight of maleic acid 1.5 parts, polymethyl methacrylate crosslinked fine particles (manufactured by Sekisui Chemical Co., Ltd., MBX20, average particle size 2)
(0 .mu.m) and a coating solution containing 0.02 parts of a silicone release agent, and dried at 120.degree. C. for 5 minutes to form an ink absorbing layer having a thickness of 15 .mu.m. Then, a dope in which 100 parts of cyclohexanol was added to 100 parts of a 10% acetone solution of cellulose acetate (average acetylation degree: 55, viscosity average polymerization degree: 170) was applied, and 80 ° C., 9
It was dried under an atmosphere of 0% RH for 3 minutes to give an average pore diameter of 0.1%.
An 8 μm thick porous layer in which 9 μm pores existed at high density was formed. Table 1 shows the evaluation results of the recording sheet.

Example 4 A 15% aqueous solution of modified polyvinyl alcohol (OKS-7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied on a 100 μm-thick polyethylene terephthalate film (Melinex 705, manufactured by DuPont Japan) which had been subjected to an easy adhesion treatment.
Parts by weight of maleic acid 1.5 parts, polymethyl methacrylate crosslinked fine particles (manufactured by Sekisui Chemical Co., Ltd., MBX20, average particle size 2)
0 μm) is applied at 120 ° C.
For 5 minutes to form an ink absorbing layer having a thickness of 15 μm.
5. Viscosity average degree of polymerization 170) A dope in which 100 parts of cyclohexanol is added to 100 parts of an acetone solution having a content of 10% is applied, and dried at 80 ° C. and 90% RH for 3 minutes to obtain an average pore diameter of 0%. A porous layer having a thickness of 8 μm in which holes having a diameter of 0.9 μm existed at high density was formed. Table 1 shows the evaluation results of the recording sheet.

Comparative Example 1 100 parts of a 15% aqueous solution of polyvinyl alcohol or a derivative thereof (manufactured by Kuraray, PVA217) was added to 100 parts of maleic acid on a 100 μm-thick polyethylene terephthalate film (Melinex 705, manufactured by DuPont Japan) which had been subjected to an easy adhesion treatment. Of a coating solution containing 1.5 parts of
After drying at 0 ° C. for 5 minutes, an ink absorbing layer having a thickness of 15 μm was provided. Table 1 shows the evaluation results of the obtained recording sheets.

[0108]

[Table 1]

Example 5 After the same printing as in the ink absorption test was performed on the recording sheet obtained in Example 1, the interlayer adhesive strength (Fp) was measured. Table 2 shows the results together with the interlayer adhesion strength (Fn) measured earlier. Note that the cyan, magenta, and yellow portions had the same tendency, and are therefore represented by data of the cyan portion as a representative (the same applies hereinafter).

Next, a surface protection sheet (LAG Protect G055AV5 manufactured by Sakurai Co., Ltd.) is applied to the printed sheet surface.
0: with adhesive) was laminated on the porous layer. Then, the surface protection sheet integrated with the porous layer was peeled off from the recording sheet. At the time of peeling, the peel resistance of the image area was large and the porous layer was partially torn, but peeled between the porous layer and the ink absorbing layer. Table 2 shows the results of the water resistance-2 test.

Example 6 After the same printing as in the ink absorption test was performed on the recording sheet obtained in Example 2, the interlayer adhesive strength (Fp) was measured. Table 2 shows the results together with the interlayer adhesion strength (Fn) measured earlier.

Next, a surface protection sheet (LAG Protect G055AV5, manufactured by Sakurai Co., Ltd.) is applied to the sheet surface after printing.
0: with adhesive) was laminated on the porous layer. Then, the surface protection sheet integrated with the porous layer was peeled off from the recording sheet. At the time of peeling, the peel resistance of the image area was large and the porous layer was partially torn, but peeled between the porous layer and the ink absorbing layer. Table 2 shows the results of the water resistance-2 test.

Example 7 After the same printing as in the ink absorption test was performed on the recording sheet obtained in Example 3, the interlayer adhesive strength (Fp) was measured. Table 2 shows the results together with the interlayer adhesion strength (Fn) measured earlier.

Next, a surface protection sheet (LAG Protect G055AV5, manufactured by Sakurai Co., Ltd.) is applied to the printed sheet surface.
0: with adhesive) was laminated on the porous layer. Then, the surface protection sheet integrated with the porous layer was peeled off from the recording sheet. The porous layer was peeled between the porous layer and the ink absorbing layer with an appropriate peel resistance without tearing. Table 2 shows the results of the water resistance-2 test.

Example 8 After the same printing as in the ink absorption test was performed on the recording sheet obtained in Example 4, the interlayer adhesive strength (Fp) was measured. Table 2 shows the results together with the interlayer adhesion strength (Fn) measured earlier.

Then, a surface protective sheet (LAG Protect G055AV5 manufactured by Sakurai Co., Ltd.)
0: with adhesive) was laminated on the porous layer. Then, the surface protection sheet integrated with the porous layer was peeled off from the recording sheet. The porous layer was peeled between the porous layer and the ink absorbing layer with an appropriate peel resistance without tearing. Table 2 shows the results of the water resistance-2 test.

[0117]

[Table 2]

Table 2 also shows the results of the water resistance-2 test of the recording sheets obtained in Examples 1 to 4. In comparison with these, the recording sheets obtained in Examples 5 to 8 It showed remarkably high water resistance. Therefore, the recording sheets obtained in Examples 5 to 8 can realize high water resistance that can withstand outdoor use such as sign displays.

Comparative Example 2 100 parts of a 15% aqueous solution of modified polyvinyl alcohol (OKS-7158G, manufactured by Nippon Synthetic Chemical Co., Ltd.) was applied on a 100 μm-thick polyethylene terephthalate film (Melinex 705, manufactured by DuPont Japan) which had been subjected to an easy adhesion treatment. A coating solution containing 1.5 parts of maleic acid was applied, and 12
After drying at 0 ° C. for 5 minutes, an ink absorbing layer having a thickness of 15 μm was provided. Next, an adhesive for dry lamination (AD563, manufactured by Toyo Morton Co., Ltd.) was applied and dried at 70 ° C. for 2 minutes to form an adhesive layer having a thickness of 2 μm. Further, on this, cellulose acetate (average acetylation degree 55, viscosity average polymerization degree 170)
Cyclohexanol 1 in 100 parts of acetone 10% solution
A dope to which 00 parts are added is applied, and 80 ° C., 90% RH
Was dried for 3 minutes in the atmosphere described above to form a porous layer having a thickness of 8 μm in which pores having an average pore diameter of 0.9 μm were present at high density.

When the interlayer strength was measured, the porous layer and the ink-absorbing layer were firmly adhered to each other by the adhesive layer, and could not be measured because the porous layer was cohesively broken.

When the ink absorbency was evaluated, it took 2 minutes or more. It is estimated that the ink absorbing layer did not function sufficiently because the adhesive layer was interposed between the porous layer and the ink absorbing layer. Further, as in Example 5, the surface protective film was laminated and tried to be peeled off, but the printed image was crushed due to cohesion failure of the porous layer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/00 C08K 5/101 5/101 C08L 31/04 G C08L 31/04 83/04 83/04 91 / 06 91/06 B41J 3/04 101Y 101/16 101Z C08L 101/00 F term (reference) 2C056 EA04 EA13 FB01 FB02 FB08 FC06 HA44 2H086 BA02 BA16 BA31 BA35 BA41 4D075 AC22 AC23 BB24Y CA08 CA35 DA04 DB48 DC27 EB07 EB07 EB07 EB07 EB52 EC03 4F006 AA02 AA12 AA15 AA16 AA35 AA36 AA38 AB02 AB20 AB23 AB24 AB32 BA01 CA01 DA04 4J002 AA011 AE032 BF021 CC183 CC193 CD013 CD183 CH053 CP032 EC077 EH036 EW067 EX037 EZ007 FD143 FD 143 FD143 FD

Claims (20)

[Claims] 1. An ink absorbing layer comprising: a base material; an ink absorbing layer formed on at least one surface of the base material; and a porous layer formed on the ink absorbing layer. A recording sheet that is peelable. 2. The recording sheet according to claim 1, wherein the interlayer adhesive strength between the porous layer and the ink absorbing layer is 1 to 500 g / 15 mm. 3. The recording sheet according to claim 1, wherein the interlayer adhesive strength between the porous layer and the ink absorbing layer is 1 to 200 g / 15 mm. 4. The recording sheet according to claim 1, wherein the interlayer adhesive strength between the porous layer and the ink absorbing layer is 7 to 200 g / 15 mm. 5. In a recording sheet after image formation, the interlayer adhesive strength between the porous layer and the ink absorbing layer in the non-image area is defined as Fn, and the interlayer adhesive strength between the porous layer and the ink absorbing layer in the image area is defined as Fn. The recording sheet according to claim 1, wherein the following formula (1) is satisfied when Fp is satisfied. | Fp-Fn | <150g / 15mm (1) 6. The recording sheet according to claim 1, wherein the ink absorbing layer is made of a water-soluble polymer or a water-absorbing polymer, and the porous layer is made of a hydrophilic polymer. 7. The recording sheet according to claim 1, wherein the ink absorbing layer is formed of a vinyl acetate polymer, and the porous layer is formed of cellulose acetate. 8. The ink-absorbing layer according to claim 1, wherein the ink-absorbing layer is composed of a cross-linkable or curable water-soluble polymer or a water-absorbing polymer, and has a releasability from the porous layer. Sheet for recording. 9. The recording sheet according to claim 1, wherein the ink absorbing layer contains a release agent. 10. The recording sheet according to claim 1, wherein the ink absorbing layer contains a crosslinking agent or a curing agent. 11. The recording sheet according to claim 1, wherein the ink absorbing layer contains fine particles. 12. The porous layer having an average pore size of 0.005 to 1
The recording sheet according to claim 1, which has a thickness of 0 µm. 13. The method according to claim 1, wherein the thickness of the ink absorbing layer is 5 to 50 μm, and the thickness of the porous layer is 1 to 100 μm.
Recording sheet as described. 14. The light transmittance at a wavelength of 400 nm is 45%.
The recording sheet according to claim 1, which is as described above. 15. A method for producing a recording sheet, comprising: forming an ink absorbing layer on at least one surface of a base sheet; and forming a porous layer peelable from the ink absorbing layer. 16. A coating liquid containing a polymer, a release agent and at least one of fine particles to form an ink absorbing layer, and a coating liquid containing a polymer on the ink absorbing layer. The method for producing a recording sheet according to claim 15, wherein the recording layer is applied to form a hole in the porous layer in the film forming step. 17. A polymer, a good solvent for the polymer,
17. A porous layer is formed by applying a coating liquid composed of a solvent having a higher boiling point than the good solvent and a poor solvent for the polymer on the ink absorbing layer and drying the coating liquid. Of manufacturing a recording sheet. 18. A polymer, a good solvent for the polymer,
And a poor solvent for the polymer and a coating solution composed of a solvent having a higher boiling point than the good solvent is applied on a substrate, and the porous layer prepared by drying is dried to form an ink absorbing layer. The method for producing a recording sheet according to claim 15, wherein the recording sheet is laminated thereon. 19. A method for forming a recorded image, comprising: after recording an image on the porous layer of the recording sheet according to claim 1, separating the porous layer from the ink absorbing layer. 20. After recording an image on the porous layer of the recording sheet according to claim 1, a cover sheet is laminated and integrated on the porous layer, and the cover sheet and the porous layer are further ink-absorbed. A method of forming a recorded image peeled from a layer.