JPH11216946A - Recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have an ink receiving layer with image clearness and water resistance, and make it adaptable to the image formation by water ink by containing water absorptive polyurethane urea at a specific percent by weight in which a square root of the amount of water absorption and contact time of water by a bristore method satisfies a specific relation. SOLUTION: On at least one surface of a base material, there is provided an ink receiving layer containing a water absorptive polyurethane urea (A, B and so forth), wherein a square root √T(mesc<1/2> ) of the amount of water absorption V (ml/m<2> ) and contact time of water by bristore method meets a 1.9027 e<x> <V<34.321 e<y> (however, X=0.0427√T, y=0.0352√T) in √T<70 msec<1/2> . Herein, water absorptive urethane urea not satisfying (a lower limit value) <V< (an upper limit value) is not adaptable to use. A surface free energy of the ink receiving layer is 35-70 mN/m. Also, a hydrogen binding component (γh) of the surface free energy of the ink receiving layer is 2-25 mN/m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material for forming an image using an aqueous ink.

[0002]

2. Description of the Related Art In recent years, in the printing industry, organic solvents in ink have been receiving attention due to problems such as improvement of the working environment at a printing site, air pollution, and the like. Attention has been paid. Water-based inks (1) save petroleum resources compared to solvent-based inks,
(2) Low impact of environmental pollution and high occupational safety;
(3) It is non-flammable and reduces the risk of fire, reduces the burden on facilities such as explosion-proof equipment and dangerous goods warehouses, and (4) reduces the odor of printed matter due to residual solvents. On the other hand, water-based inks are slow to dry after printing, causing problems such as ink leveling, bleeding, and blocking due to poor drying. At present, printing on recording materials is not widely used.

As a printing method using an aqueous ink, there are ink jet printing, gravure printing, flexographic printing, and the like. Among them, ink jet printing is low in noise, high speed printing and multicolor printing are possible, and in recent years, the resolution is low. The improvement has been achieved, and the image quality has been significantly improved. In addition, with the release of low-cost personal inkjet printers, their use in homes and offices is rapidly being promoted. Ink used for inkjet printing is
Most of them are water-based because of problems such as odors, and as the recording material for receiving ink, there are papers such as plain paper, synthetic paper, and those in which an ink-receiving layer is provided on the surface of a plastic substrate such as an OHP sheet. in use.

[0004] These recording materials are required to have not only rapid ink absorbency but also excellent ink fixability, color development, sharpness and image gradation. Furthermore,
It is required that a recorded image subjected to ink jet recording has excellent image storability and durability, particularly excellent water resistance and light resistance (weather resistance). Therefore, on the surface of the recording material, an ink receiving layer containing a water-soluble resin or an inorganic filler such as silica and a hydrophilic resin is provided, and in order to satisfy various characteristics as described above, various ink-receiving layers are provided. Something has been devised.

Heretofore, an ink receiving layer provided on a recording material of an aqueous ink has been composed of a reaction product of an isocyanate compound and a polyether polyol (JP-A-60-248387, JP-A-61-32787).
Japanese Patent Application Laid-Open No. 60-56587), those containing polyvinylpyrrolidone (Japanese Patent Application Laid-Open No. 2-243380), filling a filler to form a porous film, (Japanese Patent Application Laid-Open No. 62-79237) and the like have been proposed. However, although these are excellent in ink absorption and image clarity, they have a drawback that they are inferior in water resistance. In addition, there is no conventional recording material that simultaneously satisfies the drying property of the aqueous ink at the time of printing, the image clarity (coloring properties, bleeding, etc.) of the printed matter, and the water resistance. Recording materials are required.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording material which has an ink receiving layer which is excellent not only in image clarity but also in water resistance and which is used for image formation using a water-based ink. And

[0007]

SUMMARY OF THE INVENTION In ink jet recording, it is necessary that water-based ink rapidly penetrates a recording material. If the permeation is slow, the ink spreads on the surface and the dots become larger (dot gain), the inks of different colors are mixed, the color becomes dirty, and the fixing time after printing becomes longer. The present inventors used a dynamic scanning absorptiometer (Bristow method) as an index of the ink absorption rate.
Of the water absorption by the Bristow method and the square root of the contact time of water satisfy 50-100% by weight of the water-absorbing polyurethane urea, so that the water resistance is improved. It has been found that the ink receiving layer has a good balance between the water absorption and the water absorption and is excellent in image clarity.

That is, according to the present invention, on at least one surface of the substrate, the water absorption V (ml / m ² ) by the Bristow method and the square root of the contact time of water ΔT (msec ^1/2 ) are expressed by ΔT < 70msec
In ^{1/2 1.9027e x} <V ^<34.321e
y (however, x = 0.0427 {T, y = 0.0352}
T. 50-1 water-absorbing polyurethane urea satisfying
The present invention relates to a recording material provided with an ink receiving layer containing 00% by weight. The present invention also relates to the recording material, wherein the surface free energy of the ink receiving layer is 35 to 70 mN / m.

Further, according to the present invention, the hydrogen bonding component (γh) of the surface free energy of the ink receiving layer is 2 to 25 mN / m.
The recording material described above, The present invention also relates to the recording material, wherein the polyurethane urea contains 40 to 70% by weight of a polyethylene oxide chain. Furthermore, the present invention relates to the above recording material, wherein the weight average molecular weight of the polyurethane urea is 1.5 × 10 ^{4 to} 1.0 × 10 ⁵ .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid absorption behavior is based on the following Luc based on a model of a cylindrical vertical capillary tube as its basic principle.
It is described by an as-Washburn equation. H = (γrTcos θ / 2η) 1/2 H: depth of penetration of liquid into capillary r: radius of capillary γ: surface free energy of liquid θ: contact angle between liquid and capillary T: contact time

That is, the penetration depth of the liquid is proportional to the square root of time, and the proportionality coefficient is determined by the viscosity and surface free energy of the liquid, the inner diameter of the capillary, and the contact angle between the liquid and the inner surface of the capillary. However, in the Lucas-Washburn equation, what should be a straight line passing through the origin has an intercept or bends. This is thought to be due to simultaneous occurrence of phenomena such as wetting delay and transfer of liquid to unevenness.

[0012] recording material water absorption of the water absorbent polyurethane urea contained in the ink receiving layer V (ml / m ²⁾ is 1.9027E ^x of the present invention (where, x = 0.0427√T) is less than Since the water absorption speed is low, the water-based ink does not dry on the ink receiving layer, causing a dot gain or mixing of inks of different colors, resulting in poor color developability. The water absorption V (ml / m ² ) is 34.321 e ^y (where y = 0.03)
If the temperature exceeds 52 ° T), the ink receiving layer containing the water-absorbing polyurethane urea will peel off from the substrate due to swelling with water.

The water-absorbing polyurethane urea can be obtained by reacting a hydroxy compound, an isocyanate compound, an amine compound, and, if necessary, a compound having a group capable of reacting with an isocyanate group and an ionic functional group. As the hydroxy compound, low molecular weight polyols, high molecular weight polyols, bisphenols such as bisphenol A and bisphenol F, glycols obtained by adding an alkylene oxide such as ethylene oxide and propylene oxide to bisphenols, and the like can be used. .

The low molecular weight polyols include ethylene glycol, diethylene glycol, triethylene glycol, butanediol, propanediol, 1,6-
Diols such as hexanediol, neopentyl glycol, cyclohexanedimethanol, 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,2,8,10-tetraoxospiro [5,5] undecane Glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, methylglucoside and the like.

The high molecular weight polyols include polyether polyols and polyester polyols. Examples of polyether polyols include, for example, tetrahydrofuran, or a polymer, copolymer or graft copolymer of alkylene oxide such as ethylene oxide, propylene oxide or butylene oxide, or hexanediol, methylhexanediol, heptanediol, or octanediol. Alternatively, polyether glycols obtained by condensation of these mixtures and the like can be mentioned.

Examples of the polyester polyols include ethylene glycol, propylene glycol,
3-butanediol, 1,4-butanediol, neopentyl glycol, hexanediol, methyl-1,5
-Pentanediol, octanediol, cyclohexanediol, 2-ethyl-1,3-hexanediol,
Polyester polyol obtained by a condensation reaction from a saturated or unsaturated low molecular weight glycol such as bisphenol A, diethylene glycol, triethylene glycol, dipropylene glycol, and an aliphatic or aromatic dibasic acid or aromatic dibasic ester, Examples thereof include polyester polyols, polycarbonate polyols, and silicone polyols obtained by ring-opening polymerization of a cyclic ester compound such as ε-caprolactone, and a reaction product of a terminal hydroxyl group obtained by reacting these with a diisocyanate can also be used.

When the water-absorbing polyurethane urea contains polyethylene oxide (EO) chains formed by ethylene oxide or ethylene glycol in the range of 40 to 70% by weight, appropriate water absorption is imparted, and absorption of water-based ink is achieved. Is preferable because it becomes better. When the content of the EO chain is less than 40% by weight, the ink absorbency is slow, and a dot gain (dot swelling) or bleeding occurs, so that it is difficult to obtain a clear image. On the other hand, if the content of the EO chain exceeds 70% by weight, the tackiness becomes strong and causes blocking, and the water resistance also decreases. In particular, it is preferable that the EO chain is contained in the water-absorbing polyurethane urea in the range of 45 to 60% by weight because the water absorbing property, the water resistance and the film-forming property of the ink receiving layer can be balanced.

As the isocyanate compound, a conventionally known one such as hexamethylene diisocyanate (H
DI), dodecamethylene diisocyanate, isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), tolylene diisocyanate (T
DI), diphenylmethane diisocyanate (MD
I), trimers of IPDI, TDI and HDI, crude T
DI, polyphenylmethane polyisocyanate (PAP
I), naphthylene diisocyanate, and modified isocyanates thereof can be used. The isocyanate-modified product has one or more functional groups of a carbodiimide group, a uretdione group, a uretoimine group, a buret group, and an isocyanurate group.
Above all, non-yellowing isocyanate compounds such as HDI, XDI, IPDI and hydrogenated MDI are preferably used from the viewpoint of weather resistance.

The amine compound is used as an active hydrogen compound at the time of synthesizing the isocyanate prepolymer at both ends described later or as a chain extender at the time of chain extension of the prepolymer. As specific examples, ethylenediamine,
Propylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, triethylene tetramine, diethylene triamine, triamino propane, isophorone diamine,
Examples thereof include aliphatic polyamines including alicyclic polyamines such as dicyclohexylmethane-4,4'-diamine and aromatic polyamines such as phenylenediamine and xylylenediamine. Furthermore, intramolecular molecules such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine And dimer diamines obtained by converting a carboxyl group of dimer acid into an amino group.

In extending the chain of the prepolymer, a monoamine compound may be used as a reaction terminator (molecular weight modifier), if necessary. Examples of the monoamine compound include dialkylamines such as di-n-butylamine, monoethanolamine, diethanolamine,
Amines having a hydroxyl group such as -amino-2-methyl-1-propanol, tri (hydroxymethyl) aminomethane, 2-amino-2-ethyl-1,3-propanediol, monomethylhydrazine, 1,1-dimethylhydrazine; Examples thereof include alkyl hydrazines such as benzyl hydrazine, and hydrazides such as form hydrazide, aceto hydrazide, and lauric hydrazide.

The compound having a group capable of reacting with an isocyanate group and an ionic functional group is used mainly for improving the adhesion of polyurethane urea to a substrate. Examples of the ionic functional group include a quaternary ammonium group, a tertiary amino group, a carboxylate group, a carboxyl group, a sulfonate group, a sulfonic group, a phosphonium group, a phosphinic group, and a sulfate group. Of these, precursor groups such as carboxyl groups and tertiary amino groups can be easily converted to ionic groups by neutralization or quaternization reaction with ammonia, tertiary amine, acetic acid or the like.

Specific examples of the compound having a group capable of reacting with an isocyanate group and an ionic functional group include dimethylolalkanoic acids such as dimethylolpropionic acid, dimethylolbutyric acid, and dimethylolvaleric acid; amino acids; aminosulfonic acids; Oxyalkylation products and polyesterification products, diaminocarboxylic acid, sodium diaminobenzenesulfonate, disodium glycerin monophosphate, sodium hydroxyethylphosphonate, sodium dimethylolphosphinate, N-
Methylethanolamine, polyester polyol having 5-sodium sulfoisophthalic acid skeleton, carboxyl group-containing polyester polyol obtained by addition / condensation reaction of low molecular weight glycol and aliphatic or aromatic polybasic anhydride, dimethylolalkanoic acid Examples of the initiator include a carboxyl group-containing polyol obtained by ring-opening polymerization of a lactone. Of these, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolalkanoic acid having a low molecular weight such as dimethylolvaleric acid has a catalytic action at the time of reaction, and is preferably used from the viewpoint of improving the film formability of the ink receiving layer. Used.

In order to synthesize the water-absorbing polyurethane urea, a hydroxy compound, an isocyanate compound, an amine compound and, if necessary, a compound having a group capable of reacting with an isocyanate group and an ionic functional group are prepared at room temperature according to a conventionally known method. The reaction is carried out at -140 ° C, preferably 40-100 ° C. Examples of the synthesis method include a one-shot method in which these compounds are reacted in a batch charge, and a prepolymer method in which a high molecular weight is adjusted and the molecular weight is adjusted with a chain extender and / or a reaction terminator after producing a terminal isocyanate prepolymer. However, the latter method is particularly preferred.

The synthesis of polyurethane urea by the prepolymer method includes, for example, the reaction of an active hydrogen compound (a compound having an active hydrogen group) such as a hydroxy compound or an amine compound, an isocyanate compound, and, if necessary, a group capable of reacting with an isocyanate group. The reaction is carried out by reacting a compound having an ionic functional group with an isocyanate group in excess of isocyanate groups with a chain extender and / or a reaction terminator at both ends isocyanate prepolymer to increase the molecular weight and adjust the molecular weight. That is, an excess isocyanate group is reacted with an active hydrogen group (hydroxyl group or amino group) to produce an isocyanate prepolymer at both ends, and then reacted with an amine compound as a chain extender to form a urea bond. Perform molecular weight control and molecular weight control. By generating this urea bond, tackiness on the surface of a polyurethane resin, particularly a polyurethane resin having a polyethylene oxide chain, can be reduced, and the film strength of the ink receiving layer can be improved.

The equivalent ratio of the isocyanate group to the active hydrogen group at the time of preparing the isocyanate prepolymer at both ends in the prepolymer method is suitably in the range of 1.01 to 4.00, preferably 1.40 to 3.00. . Further, if necessary, a conventionally known urethanization catalyst, for example, dibutyltin dilaurate, tin octylate, triethylamine,
N, N-dimethylbenzylamine, sodium hydroxide,
Diethyl zinc tetra (n-butoxy) titanium or the like can be used.

The production of the prepolymer can be carried out without a solvent, but a solvent can also be used for homogenizing the reaction and adjusting the viscosity. As the solvent, specifically, acetone,
Examples thereof include methyl ethyl ketone, ethyl acetate, dioxane, acetonitrile, tetrahydrofuran, diglyme, dimethyl sulfoxide, N-methylpyrrolidone, toluene, and the like, and a single or a mixture thereof is used.

In the chain extension / reaction stopping step following the prepolymerization, a solution obtained by diluting a chain extender and / or a reaction terminator may be dropped on the prepolymer to cause a reaction. Can be added dropwise to the solution of the chain extender and / or the reaction terminator to cause the reaction. The amount of the chain extender and / or the reaction terminator used is 0.1 to 1 equivalent of the terminal isocyanate group in the prepolymer.
An amount of 5 to 3.0 is desirable. Outside this range, the film-forming properties deteriorate, and adverse effects such as discoloration are observed. The chain extension reaction is carried out at room temperature to depending on the reactivity between active hydrogen and isocyanate.
It can be performed in the range of 95 ° C.

The water-absorbing polyurethane urea can be dispersed or dissolved in water before, at the same time as, or after or after the chain extension / reaction stop. The conversion of a precursor group, for example, a carboxyl group, into an ionic group in the water-absorbing polyurethane urea may be performed before, simultaneously with, or after the addition of the polyurethane urea to water. Basic compounds used for neutralizing carboxyl groups include ammonia, monoethylamine, diethylamine, trimethylamine, triisopropylamine, tributylamine, triethanolamine, methyldiethanolamine, monoethanolamine, dimethylethanolamine, diethylethanolamine, and morpholine. , N-methylmorpholine, organic amines such as 2-amino-2-ethyl-1-propanol, inorganic alkalis such as sodium hydroxide and potassium hydroxide, and the like, and one or more kinds are used in combination. . Among them, those which are water-soluble and have high volatility which are easily dissociated by heat are preferable, and ammonia, trimethylamine and triethylamine are particularly preferable.

Weight average molecular weight of water-absorbing polyurethane urea
The quantity is 1.5 × 10^Four ~ 1.0 × 10 ^Five In the range of
Is preferred. Weight average molecular weight is 1.5 × 10^Four Less than
In this case, the surface of the ink receiving layer has a strong tack and is blocked.
And the water resistance is also poor. Also, 1.0 ×
10^Five If it is larger, the solubility in a solvent is reduced, and
Increase to a gel state, so that a uniform film is formed during coating.
Cannot be formed. Surface tack, water resistance and dissolution
From the balance of resolvability, the weight average molecular weight is 1.8 × 10^Four 
~ 5.0 × 10^Four Is more preferably within the range.

In order to prevent blocking, prevent curling, adjust surface gloss, improve weather resistance, and improve wettability of ink droplets, the ink-receiving layer may be made of polyurethane, non-water-absorbent, in addition to the above-mentioned water-absorbent polyurethaneurea. Polyurethane urea, polyether polyol, saturated polyester, polyvinyl chloride, acrylic resin, polyvinyl acetate, polyvinyl acetal, polystyrene, fluororesin, polycarbonate, polyether, polyisobutylene, polyamide, petroleum resin, rosin, nitrocellulose, sucrose ester, Vinyl chloride / vinyl acetate copolymer, ethylene /
Thermoplastic resins such as vinyl acetate copolymers, α-olefin / maleic anhydride copolymers, styrene / maleic anhydride copolymers, phenolic resins, urea resins, melamine resins, unsaturated polyesters, alkyd resins, Silicon resins, thermosetting resins such as epoxy resins, epoxy acrylates, polyester acrylates, urethane acrylates, polyether acrylates, resins that are cured by ultraviolet rays or electron beams such as phosphazene resins, as long as the object of the present invention is not hindered. One or more kinds can be blended.

Further, silica, alumina, diatomaceous earth,
Extenders such as talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide,
UV absorbers, fluorescent dyes such as fluorescent brighteners, coloring dyes / pigments, thickeners, leveling agents, crater inhibitors, anti-settling agents, antioxidants, flame retardants, waxes, heat stabilizers, etc.
It can be added as appropriate. Among them, silica and alumina not only do not impair the appearance of the ink receiving layer, but also have the purpose of imparting hydrophilicity or water absorption, as well as preventing blocking, adjusting the dot diameter of ink droplets, adjusting the surface gloss, etc. It is suitable because it can be used for the purpose of (1).

The ink receiving layer can be provided by coating at least one surface of the base material with a coating of the components of the ink receiving layer by a conventionally known method. The ink receiving layer has a thickness of 5 to 100 μm on one or both sides of the substrate, and more preferably 10 to 50 μm, from the viewpoint of ink absorption.
It is preferably formed with a thickness of μ. Coating is, for example, spray, spin coater, die coater,
It is performed using a gravure coater, knife coater, dip coater, comma coater, or the like.

Examples of the substrate on which the ink receiving layer is provided include paper, polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, polyvinylidene fluoride, hard polyvinyl chloride, polyvinylidene chloride, nylon, polyimide, polystyrene, polyvinyl alcohol, Plastic films such as ethylene / vinyl alcohol copolymer, polycarbonate, polyacrylonitrile, polybutene, soft polyvinyl chloride, polyvinylidene fluoride, polyethylene, polypropylene, polyurethane, ethylene-vinyl acetate copolymer, and polyvinyl acetate can be used. In addition, various nonwoven fabrics, synthetic papers, metal foils, or composite sheets combining these, metals,
It can also be provided on glass or the like. In order to improve the adhesion, the surface of the substrate may be coated with a corona treatment, a plasma treatment, or a resin having excellent adhesion to the substrate, as long as the object of the present invention is not hindered.

The ink receiving layer of the present invention has a surface free energy of 35 to 70 mN / m in order to simultaneously satisfy the absorptivity, bleeding, and fixability of the aqueous ink and the stability of the ink receiving layer against changes in humidity over time. It is preferred that Surface free energy is water, methylene iodide, α
The contact angle is measured immediately after the three droplets of bromonaphthalene are dropped onto the ink receiving layer (after 0.1 second), and the contact angle is determined by the Wu theory or the extended Fowkes theory. The required surface free energy γ satisfies the following component division and addition rule in any theory, and shows substantially the same value in any theory.

Wu's Theory γ = γd1 + γp1 γ: Surface Free Energy of Solid Surface γd1: Dispersive Force Component of Surface Free Energy of Solid Surface γp1: Dipole Force Component of Surface Free Energy of Solid Surface

Extended Fowkes' Theory γ = γd2 + γp2 + γh γ: Surface Free Energy of Solid Surface γd2: Dispersive Force Component of Surface Free Energy of Solid Surface γp2: Dipole Force Component of Surface Free Energy of Solid Surface γh: Solid Hydrogen bond component of the surface free energy of the surface

The surface free energy of the ink receiving layer is 35
If it is less than mN / m, the wettability of the landed ink droplets will be poor, and the dot diameter formed by the ink droplets will be small, resulting in lower color density. If it exceeds 70 mN / m, since the surface is highly hydrophilic, not only the water resistance is lowered, but also the moisture resistance is poor, and the ink receiving layer absorbs the moisture in the atmosphere and the surface becomes white with time. , The gloss may decrease. Further, the surface free energy of the ink receiving layer is preferably in the range of 45 to 65 mN / m from the viewpoint of the balance between the color developing property and the water resistance.

According to the extended Fowkes' theory, the component γh that contributes to the hydrogen bond can be separated.
h can be used as a measure of the hydrophilicity of the surface. Hydrogen bonding component of surface free energy of ink receiving layer (γ
h) is preferably 2 to 25 mN / m. γh
Is 2 mN / m, the wettability of the ink drops deteriorates,
The color density decreases. On the other hand, when γh is 25 mN / m, wettability of ink droplets is excellent, but water resistance and moisture resistance are inferior. Further, it is preferable that γh is in the range of 3 to 15 mN / m from the viewpoint of the balance between color development and water resistance.

[0039]

EXAMPLES The specific constitution of the recording material of the present invention will be described below with reference to examples, but the present invention is not limited to these. In addition, in an Example, a part represents a weight part. Mw represents a weight average molecular weight. Mw was measured by gel filtration chromatography using a refractive index detector in terms of polystyrene.

[Synthesis of Water Absorbing Polyurethane Urea A] A hydroxy compound and an isocyanate compound are dissolved in methyl ethyl ketone (MEK), octyltin is added as a catalyst, and the mixture is reacted at 85 to 90 ° C. with stirring for 3 to 4 hours. Reaction was performed until the remaining amount of isocyanate reached a predetermined amount to synthesize a prepolymer. Prepolymer at 45-55 ° C
After cooling, 10.8 parts of isophoronediamine was added as an amine compound and reacted until the isocyanate peak (2250 ^-1 cm ^-1 ) disappeared by infrared absorption measurement.
A solution of water-absorbing polyurethane urea A having a w of 2.0 × 10 ⁴ (solid content (NV) 30% by weight) was obtained. Polytetramethylene ether glycol (Mw3000) 1.3 parts Polyethylene glycol (Mw2000) 51.9 parts Dimethylolpropionic acid 6.4 parts Isophorone diisocyanate 29.6 parts

[Synthesis of water-absorbing polyurethane urea B] A solution of water-absorbing polyurethane urea B having a Mw of 2.3 × 10 ⁴ (NV 30% by weight) was obtained in the same manner as in the case of water-absorbing polyurethane urea A using the following raw materials. . Polytetramethylene ether glycol (Mw3000) 0.6 parts Polyethylene glycol (Mw1000) 60.0 parts Dimethylolpropionic acid 2.6 parts Isophorone diisocyanate 28.0 parts Isophorone diamine 8.7 parts Dibutylamine 0.1 part

[Synthesis of water-absorbing polyurethane urea C] A solution of water-absorbing polyurethane urea C having a Mw of 1.8 × 10 ⁴ (NV 30% by weight) was obtained in the same manner as in the case of water-absorbing polyurethane urea A, using the following raw materials. . Polytetramethylene ether glycol (Mw3000) 52.5 parts Polyethylene glycol (Mw2000) 5.1 parts Dimethylolpropionic acid 7.3 parts Isophorone diisocyanate 26.6 parts Isophorone diamine 7.7 parts Dibutylamine 0.8 parts

[Synthesis of water-absorbing polyurethane urea D] A solution of water-absorbing polyurethane urea D having a Mw of 1.4 × 10 ⁴ (NV 30% by weight) was obtained in the same manner as in the case of water-absorbing polyurethane urea A using the following raw materials. . Polytetramethylene ether glycol (Mw3000) 0.2 parts Polyethylene glycol (Mw1000) 71.0 parts Dimethylolpropionic acid 6.5 parts Isophorone diisocyanate 17.4 parts Isophorone diamine 4.8 parts Dibutylamine 0.1 part

Example 1 A solution (N) of a water-absorbing polyurethane urea A was placed on a polyvinyl chloride film having a thickness of 80 μm.
V30% by weight) using a bar coater to a dry film thickness of about 3
The coating material was applied so as to be 0 μm and dried at 100 ° C. for 2 minutes to obtain a recording material. (Example 2) Water-absorbing polyurethane urea B was formed on a polyvinyl chloride film having a thickness of 80 µm in the same manner as in Example 1.
(30% by weight of NV) was applied to obtain a recording material.

Example 3 A coating material having the following formulation was applied on a polyvinyl chloride film having a thickness of 80 μm in the same manner as in Example 1 to obtain a recording material. Water-absorbent polyurethane urea B solution (NV 30% by weight) 78.4 parts Acrylic resin varnish 17.7 parts ("Acryt QT510-15LV" manufactured by Taisei Kako Co., NV 38% by weight) Aliphatic polyisocyanate solution 2.2 parts (Sumitomo) 1.7 parts of silica ("Mizukasil CP-402" manufactured by Mizusawa Chemical) "Sumidur N-75" manufactured by Bayer Urethane Co., NV75% by weight

Example 4 Water-absorbing polyurethane urea B
The solvent is removed (MEK) at 70 ° C. while ion-exchanged water and 25% by weight ammonia water are dropped into the solution of
By weight, an aqueous emulsion of water-absorbing polyurethane urea B was obtained. A coating agent having the following formulation was prepared using the obtained aqueous emulsion, and was coated on a polyvinyl chloride film having a thickness of 80 μ in the same manner as in Example 1 to obtain a recording material. Aqueous emulsion of modified polyester resin 30.4 parts ("NS63P" manufactured by Takamatsu Yushi Co., NV 18% by weight) Aqueous emulsion of water-absorbing polyurethane urea B 45.6 parts Polyethylene glycol (Mw40000) aqueous solution (NV 5% by weight) 22.8 parts 1.2 parts of silica ("Mizukasil CP-402" manufactured by Mizusawa Chemical)

Comparative Example 1 A water-absorbing polyurethane urea C solution (NV 30% by weight) was applied on an 80 μm thick polyvinyl chloride film in the same manner as in Example 1 to obtain a recording material. (Comparative Example 2) Water-absorbing polyurethane urea D was formed on a polyvinyl chloride film having a thickness of 80 µm in the same manner as in Example 1.
(30% by weight of NV) was applied to obtain a recording material. Comparative Example 3 An aqueous emulsion of a modified polyester resin (“NS63P” manufactured by Takamatsu Yushi Co., Ltd., NV1) was formed on a polyvinyl chloride film having a thickness of 80 μ in the same manner as in Example 1.
8% by weight) to obtain a recording material.

Comparative Example 4 A coating material having the following formulation was applied on a polyvinyl chloride film having a thickness of 80 μm in the same manner as in Example 1 to obtain a recording material. Polyvinylpyrrolidone aqueous solution 75.2 parts (“K-90, NV15% by weight, manufactured by Gokyo Sangyo Co., Ltd.) Aqueous emulsion of styrene acrylic resin 23.6 parts (“ Johncryl 840 ”, manufactured by Johnson Polymer, NV43% by weight) Silica (Mizusawa) "Mizukasil CP-402" manufactured by Kagaku Co.) 1.2 parts

Comparative Example 5 Water-absorbing polyurethane urea A
The solvent is removed (MEK) at 70 ° C. while ion-exchanged water and 25% by weight ammonia water are dropped into the solution of
By weight, an aqueous emulsion of water-absorbing polyurethane urea A was obtained. A coating agent having the following formulation was prepared using the obtained aqueous emulsion, and was coated on a polyvinyl chloride film having a thickness of 80 μ in the same manner as in Example 1 to obtain a recording material. Polyvinyl alcohol aqueous solution 62.4 parts (Kuraray “PVA117”, NV 15% by weight) Polyethylene glycol (Mw40000) aqueous solution (NV 5% by weight) 11.2 parts Water-absorbent polyurethane urea A aqueous emulsion 25.0 parts Silica (Mizusawa Chemical) (Mizukasil CP-402) 1.4 parts

Comparative Example 6 A coating material having the following formulation was applied on a polyvinyl chloride film having a thickness of 80 μm in the same manner as in Example 1 to obtain a recording material. 99.5 parts of MEK solution of acrylic resin ("Dianal BR100" manufactured by Mitsubishi Rayon Co., NV 20% by weight) 0.5 parts of silica ("Mizukasil CP-402" manufactured by Mizusawa Chemical Co., Ltd.)

The water absorption by the Bristow method of the water-absorbing polyurethane urea A to the water-absorbing polyurethane urea D and the resin used in Comparative Example 3 for reference were measured using a dynamic scanning absorptiometer ("KM350D" manufactured by Kyowa Seiko Co., Ltd.). Was measured by FIG. 1 and FIG. 2 (enlarged views of FIG. 1) show data of water absorption by the Bristow method. The water used was distilled once, and then passed through an ion exchange resin. 1 and as is apparent from FIG. 2, the water absorbent polyurethane urea A and the water-absorbing polyurethane urea B is, 1.9027e ^x (lower limit) <V
<34.321e ^y (upper limit) (where x = 0.0427)
{T, y = 0.0352} T. ) Is satisfied, but the water-absorbing polyurethane urea C has a water absorption less than the lower limit,
In addition, the water-absorbing polyurethane urea D exceeds the upper limit in some ranges. The modified polyester resin used in Comparative Example 3 shows a water absorption less than the lower limit.

The obtained recording material was evaluated for ink jet printability, gravure printing ink setting property and water resistance, and the surface free energy of the ink receiving layer was measured. Table 1 shows the results. Inkjet printability is
Ink jet printer (Sharp “IO-73”
5X "), ink-jet printing was performed using a water-based pigment ink (" Excellent "manufactured by Label), and the water absorbency and printing quality of the ink were evaluated on a four-point scale. A: Very good. ：: good. Δ: Slightly poor in drying, bleeding, and coloring. ×: Poor in drying, bleeding, and coloring.

The gravure printing ink setting property was determined by using a water-based gravure ink (“Aqua King 3 Red” manufactured by Toyo Ink Manufacturing Co., Ltd.) using an electric gravure printing tester (“GP-2” manufactured by Kurashiki Boseki Co., Ltd.). And evaluated in four steps. A: Very good. ：: good. Δ: Slightly poor in drying, bleeding, and coloring. ×: Poor in drying, bleeding, and coloring.

The water resistance of the recording material was immersed in distilled water for 24 hours, and the degree of peeling of the ink receiving layer from the substrate was evaluated in four steps. ◎: Does not peel at all. ：: Partial peeling at the end of the recording material. Δ: Partial peeling. X: All peeled.

The surface free energy was measured using a dynamic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.), and water (equivalent to that used for measuring water absorption), methylene iodide, and α-bromonaphthalene were used. About 2 μl of the droplet was dropped on the ink receiving layer, the contact angle 0.1 second after the drop was measured, and the surface free energy of the surface of the ink receiving layer was determined using the extended Fowkes theory.

[0056]

[Table 1]

As is clear from Table 1, the recording materials obtained in the examples exhibited good results in ink jet printability, gravure printing ink setting property and water resistance.
It should be noted that the ink receiving layer of the present invention exhibited excellent water resistance despite absorbing the water-based ink. This is probably because the water-absorbing polyurethane urea is water-absorbing, but does not dissolve in water and has excellent adhesion to the substrate. In the recording material of Example 3, γ was 3
Since the values of 3.1 mN / m and γh were as small as 0.0 mN / m, the dots formed by the ink were small, and the sense of density was slightly inferior.

Comparative Example 1 is an example in which a water-absorbing polyurethane urea having a water absorption of less than the lower limit was used. I was Comparative Example 2 is an example in which a water-absorbing polyurethane urea having a water absorption of not less than the upper limit was used. However, although the ink absorption was sufficient, the water absorption was large in the water resistance test, and the ink receiving layer swelled, Peeled off. Comparative Example 3 is an example in which a resin having a water absorption less than the lower limit was used for the ink receiving layer. This recording material had a slow ink absorption and caused bleeding, so that a clear image could not be obtained. Furthermore, in the water resistance test, the ink receiving layer was dissolved in water.

Comparative Example 4 is an example in which an ink-receiving layer containing a hydrophilic resin (polyvinylpyrrolidone) and not containing a water-absorbing polyurethane urea was provided. In the test, the ink receiving layer was partially dissolved and the surface became cloudy. Comparative Example 5 is an example in which the water-absorbing polyurethane urea is less than 50% by weight based on the solid content. Although a hydrophilic resin was mixed in order to exhibit water absorption, the printability and ink setting properties were satisfactory, but the water resistance was poor. Comparative Example 6 is an example using a resin having a small water absorption.
The ink receiving layer did not absorb the ink, and the ink jet printability and the gravure printing ink setting property were poor.

[0060]

According to the present invention, it is possible to provide a recording material having not only excellent image clarity but also excellent water resistance.

[0061]

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the water absorption V of polyurethane urea and the contact time ΔT according to the Bristow method.

FIG. 2 is an enlarged view of FIG.

Claims (5)

[Claims] 1. The method according to claim 1, wherein at least one surface of the substrate has a water absorption amount V (ml / m ² ) according to the Bristow method and a square root of a contact time of water.
T (msec ^1/2) is, in √T <70msec ^1/2 1.90
27e ^x <V <34.321e ^y (however, x = 0.042
7 @ T, y=0.0352@T. A recording material comprising an ink receiving layer containing 50 to 100% by weight of a water-absorbing polyurethane urea satisfying the condition (1). 2. The ink free layer has a surface free energy of 35.
The recording material according to claim 1, wherein the recording material has a density of from 70 mN / m to 70 mN / m. 3. The recording material according to claim 2, wherein the hydrogen bonding component (γh) of the surface free energy of the ink receiving layer is 2 to 25 mN / m. 4. The recording material according to claim 1, wherein the polyurethane urea contains 40 to 70% by weight of a polyethylene oxide chain. 5. The recording material according to claim 1, wherein the weight average molecular weight of the polyurethane urea is from 1.5 × 10 ^{4 to} 1.0 × 10 ⁵ .