JP2001180104A - Recording medium forming image prominent in light- resistance, water resistance and moisture resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium forming an image prominent in light resistance, water resistance, and moisture resistance. SOLUTION: The purpose can be achieved by comprising a polymer showing hydrophobic property at a temperature lower than a transition temperature and hydrophilic property at a temperature higher than the transition temperature reversibly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium, and more particularly to a recording medium on which an image is recorded by an aqueous ink composition.

[0002] At least comprising the ink composition from the background art colorant and a solvent are widely used in character and image recording. Above all,
Aqueous ink compositions containing water as a main solvent have been used in various recording methods because of their safety and ease of handling. For example, in recent years, ink jet recording printers have become widespread. This inkjet recording method,
This is a printing method in which small droplets of an ink composition are made to fly and adhere to a recording medium such as paper to perform printing. This method has a feature that high-resolution and high-quality images can be printed at a high speed with a relatively inexpensive apparatus. In particular, color ink jet recording apparatuses have been improved in image quality and have been used as photo output machines, and have also been used as digital printing machines, plotters, CAD output devices, and the like.

[0003] In particular, an on-demand output printer is a device that can perform printing only when necessary and in a necessary amount. As a recording method of this apparatus, an ink jet recording method is preferably used. On-dot output printers using the inkjet recording method are currently in the spotlight because when printed with aqueous ink on a recording medium, the printed image has an image quality close to a silver halide photograph.

[0004] On the other hand, printed images are required to have good image quality and storage stability, especially light fastness, water fastness and moisture fastness. Since the water-based ink composition uses water as a main solvent, it is basically necessary that its components be water-soluble. Thus, the image formed thereby also consists essentially of water-soluble components. This means
It is disadvantageous from the viewpoint of water resistance and moisture resistance. That is, since components forming an image on a recording medium are water-soluble, when the image comes into contact with water, there is a possibility that these components may be redissolved in water. That is, there is a possibility that water resistance is lacking.

As a method for improving the storability of an image, a proposal has been made to impart storability to an ink composition itself and also to a method for imparting storability to an image on a recording medium. For example, JP-A-53-49113, JP-A-59-49113
198185, JP-A-60-46288 and JP-A-6
1-61887, JP-A-61-72581, JP-A-61-252189, JP-A-63-224998,
JP-A-63-307979 proposes to add a cationized polymer called an ink fixing agent to a recording medium for the purpose of improving water resistance and moisture resistance. However, when an ink fixing agent is added to a recording medium, moisture resistance and water resistance can be improved, but on the other hand, light resistance of an image may be significantly reduced.

In Japanese Patent Application Laid-Open No. Hei 10-183022,
There has been proposed an ink jet recording sheet that can perform printing with less feathering by improving ink absorbency. This sheet contains at least a thermosensitive gelling agent whose hydrophilicity and hydrophobicity change reversibly at a certain temperature.

Therefore, at present, there is still a need in the printing industry for the development of a recording medium which is excellent in light fastness, water fastness, and moisture fastness and can realize good image formation.

[0008]

SUMMARY OF THE INVENTION The present inventors have recently proposed a recording medium in which an image is recorded with ink, and the recording medium has a polymer which reversibly exhibits hydrophobicity below the transition temperature and hydrophilicity above the transition temperature. It has been found that the use of is able to unexpectedly improve the light fastness, water fastness, and moisture fastness of an image. The present invention is based on this finding.

That is, an object of the present invention is to provide a recording medium capable of realizing an image excellent in light fastness, water fastness and moisture fastness.

The recording medium according to the present invention comprises a polymer which is reversibly hydrophobic at a temperature lower than the transition temperature and hydrophilic at a temperature higher than the transition temperature, and an image is recorded by the ink composition. Things.

According to another aspect of the present invention, there is provided a recording method. The recording method according to the present invention is a recording method in which the ink composition is adhered to the recording medium according to the present invention to perform printing, and the ink composition is adhered to the recording medium at a transition temperature or lower, and then at a transition temperature or higher. Heating the recording medium.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Recording Medium The recording medium according to the present invention is used in a recording system using an aqueous ink composition. Examples of the recording method using the aqueous ink composition include an ink jet recording method, a recording method using a writing instrument such as a pen, and various other printing methods. In particular, the recording medium according to the present invention is preferably used in an ink jet recording method in which droplets of an ink composition are ejected, and the droplets are attached to the recording medium to perform printing.

The amphoteric polymer The recording medium according to the invention basically comprises a polymer. The polymer used in the present invention is an amphoteric polymer having the property of being reversibly hydrophobic below the transition temperature and hydrophilic above the transition temperature. In the present invention, the temperature at which such amphoteric polymer changes its properties is called "transition temperature". In the present invention, the transition temperature of the amphoteric polymer is about 25 ° C. or higher, preferably 30 to
The temperature is preferably in the range of about 50 ° C.

The recording medium according to the present invention comprises an amphoteric polymer in the recording medium. For this reason, it has been found that by applying the ink composition to the recording medium at a temperature equal to or lower than the transition temperature before printing, and then applying a temperature equal to or higher than the transition temperature, the ink component is fixed to the recording medium more unexpectedly. Was done. As a result, it is possible to obtain an advantage of preventing water from penetrating into the printed matter and improving water resistance and moisture resistance. Further, in the present invention, since the amphoteric polymer is used, the amount of the ink fixing agent, mainly the cationized polymer, can be reduced, and as a result, there is an advantage that the light resistance of the printed matter is improved. In the present invention, the amphoteric polymer is used by being applied to each layer of a base material, an ink receiving layer, and a gloss layer constituting a recording medium.

The amphoteric polymer according to the present invention is preferably an acrylic acid long-chain alkyl ester represented by the following formula (I).

Embedded image [In the above formula, R ¹ represents a linear or branched alkyl group having 0 to 2 (preferably 0 or 1) carbon atoms, and R ² has 12 or more carbon atoms (preferably 12, 14 ,
16 or 18) represents a linear or branched (preferably linear) alkyl group, and n is 10 ³ to 10
⁶ , preferably 10 ⁴ to 10 ⁵ ]

The amphoteric polymer is prepared by introducing a hydrophobic group and a hydrophilic group into an existing polymer, by polymerizing a monomer having a hydrophobic group and a monomer having a hydrophilic group, or by mixing a hydrophobic group and a hydrophilic group. It can be obtained by polymerizing a monomer having a group. Preferably, the polymerization is performed using a monomer having a hydrophobic group and a hydrophilic group.

In the present invention, it is preferable to use an acrylate represented by the following formula (II) as a monomer.

Embedded image [In the above formula, R ¹ represents a linear or branched alkyl group having 0 to 2 (preferably 0 or 1) carbon atoms, and R ² has 12 or more carbon atoms (preferably 12, 14 ,
16 or 18) represents a linear or branched (preferably linear) alkyl group]

When polymerizing a monomer, a polymerization initiator can be used. The polymerization initiator can be appropriately determined depending on the monomer used, and specific examples thereof include:
Examples include radical initiators such as azobisisobutyronitrile and benzoyl peroxide. Moreover, you may use a crosslinking agent as needed. Specific examples of the crosslinking agent include ethylene glycol dimethacrylate, N, N-methylbisacrylamide, and the like.

The polymerization reaction conditions depend on the amphoteric polymer to be produced.
In addition, it can be appropriately determined. For example, with a polymerization initiator
Monomer by heating under reduced pressure degassing.
Can be. The polymerization reaction can be carried out at around 50 ° C.
preferable. Average molecular weight of the amphoteric polymer in the present invention
Is 10³-10⁶Range, preferably 10
⁴-10⁵Range.

White Pigment According to a preferred embodiment of the present invention, the amphoteric polymer preferably further comprises a white pigment. The addition of the white pigment has the advantage that the absorbability of the ink composition can be further improved even when the recording medium is heated above the transition temperature. Here, “comprising” means
This means not only that the amphoteric polymer has a white pigment therein, but also that the amphoteric polymer is present by coating or spraying a white pigment before and after coating on a substrate or the like. .

Specific examples of the white pigment include silica (including amorphous silica and amorphous silica), preferably colloidal silica, silicic anhydride, hydrous silicic acid, finely divided silica, silica gel, alumina, boehmite, pseudo boehmite, Aluminum hydroxide, calcium silicate, aluminum silicate, barium sulfate, alumina sol, calcium carbonate, or silicic acids called white carbon and the like,
Preferably, silica, calcium carbonate, alumina, boehmite, pseudo-boehmite, aluminum hydroxide, calcium silicate, aluminum silicate, barium sulfate, white carbon, zeolite, and these may be used alone or as a mixture of two or more. Can be.

The average particle size of the white pigment is in the range of about 0.5 to 15 μm, and preferably in the range of about 3 to 6 μm (volume average particle diameter by Coulter counter method).

According to a preferred embodiment of the present invention, the weight ratio of the amphoteric polymer to the white pigment is from 100: 10 to 100: 2.
000, preferably 100: 30 to 1
It is preferably in the range of about 00: 100. The thickness of the layer when the amphoteric polymer is applied is not particularly limited, but is preferably about 0.1 μm to 40 μm, more preferably about 1 μm to 20 μm.

The recording medium according to the present invention contains an amphoteric polymer. In one embodiment, any member constituting the recording medium may contain the amphoteric polymer. Accordingly, one or two or more of the base material, the ink receiving layer, the gloss layer, and the like constituting the recording medium can be coated with the amphoteric polymer.

Substrate The recording medium according to the present invention is formed based on a substrate.
The substrate of the recording medium according to the present invention is not particularly limited as long as it can support a glossy layer or an ink receiving layer described below and has strength as a recording medium, and may be either transparent or opaque. Examples of the opaque substrate include cloth, wood, metal plate, paper, and the like. Further, a opaque substrate obtained by subjecting a later-described transparent substrate to opacity treatment can also be used.

According to a preferred embodiment of the present invention, it is preferable to use paper as a base material. Paper is preferably made of pulp raw material mainly composed of natural cellulose fiber, and its composition,
The production method may be appropriately determined, but for example, paper produced by a wet papermaking method is preferably used. In particular,
Wood pulp, such as kraft pulp, sulfite pulp, and semi-chemical pulp, which is prepared by using softwood or hardwood alone or as appropriate, is used as a pulp raw material, and bleached pulp is preferable in order to obtain clear printing. It is also possible to use non-wood pulp such as waste paper pulp, pagasu, kenaf, cotton, hemp, esparto, bamboo and straw.

In papermaking, a sizing agent, a wet strength agent, a filler, and a surface strength enhancer may be appropriately added as internal additives. In addition, starch, modified starch, carboxymethylcellulose, as additive chemicals for internal addition to pulp raw materials,
Internal paper strength agents such as polyacrylamide and styrene resin,
Coloring agents, fixing agents such as sulfuric acid bands and polyacrylamide,
Furthermore, in addition to the surface paper strength enhancer described later as a coating chemical, a water-resistant agent such as dialdehyde starch, melamine resin, polyamide resin, an antistatic agent, a water repellent, a friction agent, a surface sizing agent, a pigment, etc. are required. Can be used accordingly.

When a transparent substrate is selected as the substrate of the recording medium according to the present invention, specific examples thereof include polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin. Examples thereof include a resin or a film such as a polyimide resin, cellophane, and celluloid, or a plate, and a glass plate. According to a preferred embodiment of the present invention, when the substrate is transparent, a polyester film is preferable, and particularly preferably a biaxially stretched polyethylene terephthalate film on which corona treatment is performed on one or both sides is uniform without coating unevenness. It is preferable because coating properties can be obtained and good adhesion between the ink absorbing layer and the substrate can be obtained. Furthermore, it is also possible to use a polyethylene film containing a white inorganic pigment or whitened by containing fine bubbles inside the film as a base material.

The thickness of the substrate may be appropriately determined, but is generally preferably in the range of about 50 to 250 μm, and more preferably in the range of about 75 to 200 μm.

According to a preferred embodiment of the present invention, a recording medium in which the amphoteric polymer is applied to a substrate is preferred.

Ink Receiving Layer According to a preferred embodiment of the present invention, the recording medium according to the present invention may be provided with a substrate and an ink receiving layer.

The ink receiving layer of the recording medium according to the present invention comprises:
It is composed of a so-called water-soluble resin, absorbs the ink composition, forms an image by swelling, or contains fine particles, the fine particles themselves adsorb the colorant in the ink composition, or the fine particles and the fine particles Any of those which hold in a gap and form an image may be used. Further, in the recording medium according to the present invention, the ink receiving layer may be transparent or substantially opaque.

According to a preferred embodiment of the present invention, when the ink receiving layer is composed of a water-soluble resin, examples of the preferable water-soluble resin include cellulose alcohols such as polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose and carboxymethyl cellulose. Resin, polyvinylpyrrolidone, starch, casein, gelatin, polyacrylamide, styrene-butadiene copolymer latex, carboxyl-modified styrene-butadiene copolymer latex, acrylic emulsion, and the like.

When the ink receiving layer contains fine particles, the ink receiving layer is preferably formed basically of a pigment and a binder as main components. Here, as the pigment, for example, silica, clay, mica, swellable mica, talc, kaolin, diatomaceous earth, calcium carbonate,
Barium sulfate, aluminum silicate, synthetic zeolite,
Pigments such as alumina, zinc oxide, lithopone, and satin white, and organic or inorganic coloring pigments are included. As the binder, for example, acrylic resin, polyester resin, polyurethane resin, styrene-butadiene copolymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl alcohol resin, water-soluble polyvinyl acetal resin, polyvinyl butyral resin, and others Water-soluble resins and aqueous emulsions such as vinyl resins, amide resins, oxidized starch, casein, polyethylene oxide, polyvinylpyrrolidone, silicone resins, rosin-modified maleic resin, rosin-modified phenol resin, alkyd resin, and cumarone-indene resin Resins.

The ink receiving layer may contain other components for improving the characteristics of the recording medium. For example, a water-resistant agent such as a melamine formaldehyde resin, a urea formaldehyde resin, an acrylamide-based resin, glyoxal, or ammonium zirconium carbonate may be added to improve the water resistance of the ink receiving layer and impart a function of preventing ink bleeding. Further, a light stabilizer (for example, a hindered amine light stabilizer), an antioxidant, a quencher, and the like may be added. Further, a dispersant, a fluorescent dye, a pH adjuster, a defoaming agent, a wetting agent, a preservative, and the like may be added to further improve productivity, recording characteristics, or storage stability of the ink jet recording paper. Further, the ink composition for recording on the recording medium according to the present invention may contain an ultraviolet absorbent.

Preferred examples of the ink receiving layer include, for example, an ink receiving layer using fluorine-containing synthetic amorphous silica as a void-forming material described in JP-A-60-222281. In the ink receiving layer described in this publication, bleeding can be effectively controlled by setting the amount of fluorine in the synthetic amorphous silica to a specific range. Another preferred example is described in JP-A-62-95285. The ink receiving layer described in this publication uses amorphous silica for a part of the pigment, and is further manufactured by a cast coating method. This ink receiving layer has a high degree of smoothness, and a sharp print around the dots can be obtained. Another preferable example is an ink receiving layer described in JP-A-1-186372. This ink receiving layer contains polyacrylamide having a molecular weight of 10,000 to 500,000, synthetic amorphous silica, and polyvinyl alcohol, and is excellent in preservability of a recorded image.

Further, examples of other ink receiving layers include JP-A-2-276670 and JP-A-2-139275.
And JP-A-6-297831. The ink receiving layer described in these publications is provided with a porous layer made of a specific alumina hydrate, and has high roundness of ink dots, excellent fixability of a dye, and high color density printing. It is said that it can be realized. According to a preferred embodiment of the present invention, JP-A-11-115308
And an ink receiving layer disclosed in JP-A-11-58942.

According to a preferred embodiment of the present invention, a recording medium comprising a base material and an ink receiving layer, wherein the amphoteric polymer is applied to the ink receiving layer is preferable. The role of the ink receiving layer in such a recording medium is the same as described above.

Gloss Layer According to a preferred embodiment of the present invention, a gloss layer may be provided. The gloss layer here is preferably a layer provided on the outermost surface of the recording medium, and has excellent surface smoothness, gloss,
It is a layer that gives gloss.

In the recording medium according to the present invention, the gloss layer is not particularly limited, and may be a conventionally known gloss layer. The gloss layer may be composed of, for example, a white pigment and a binder component.

The white pigments may be the same as those described above. Further, as preferred white pigments, silica,
Particularly, colloidal silica is preferable. Colloidal silica is usually an anionic colloidal dispersion in which ultrafine particles of silicic anhydride (silica) are stably dispersed in water,
For example, it is manufactured as follows. First, an aqueous solution of sodium silicate is passed through a cation exchange resin to form an SiO ₂ / N
a ₂ O ratio is a sol of 60 to 130. Next, this is heated and baked at 60 ° C. or more to grow into independent dispersed particles,
The sol that has passed through the ion-exchange resin layer is further added to cause polymerization deposition. Thereby, 3 nm to 2 nm
Colloidal silica can be obtained as a stable sol by growing to an average particle diameter of 00 nm.

It is also possible to use commercially available colloidal silica, for example, Ludo manufactured by DuPont.
x, Syton manufactured by Monsanto, Nalcoag manufactured by Nalco, Snowtex manufactured by Nissan Chemical Co., Ltd. can be used.

The binder for forming the glossy layer may be appropriately selected in consideration of the production method and the like. Examples thereof include acrylic resins, polyester resins, polyurethane resins, styrene-butadiene copolymer resins, and acrylonitrile-butadiene copolymer resins. , Polyvinyl alcohol resins, water-soluble polyvinyl acetal resins, polyvinyl butyral resins, other vinyl resins, amide resins, starch oxide, casein, polyethylene oxide, polyvinylpyrrolidone, silicone resins, rosin-modified maleic resin, rosin-modified phenol Examples include water-soluble resins such as resins, alkyd resins, and coumarone-indene resins, and aqueous emulsion resins.

According to a preferred embodiment of the present invention, the glossy layer may further contain various additives for improving the characteristics of the recording medium. Preferred specific examples of such additives include an antioxidant, an ultraviolet absorber, a fluorescent brightener, a water-proofing agent, a HALS (hindered amine light stabilizer), a fading inhibitor, and an antistatic agent. .

The gloss layer can be formed by applying a coating solution prepared by dissolving or dispersing the above-mentioned components for forming the gloss layer in water or a suitable solvent, onto a substrate or an ink receiving layer. . Specific examples of the coating method include a roll coating method, a grade coating method, an air knife coating method, a rod bar coating method, a gravure coating method, a comma coating method, a die coating method, a cast coating method, and a transfer coating method.

The thickness of the gloss layer is not particularly limited.
It is preferably about 1 μm to 20 μm, more preferably 1 μm.
m to about 10 μm.

According to a preferred embodiment of the present invention, a recording medium in which an amphoteric polymer is applied to a gloss layer is preferable. The role of the gloss layer component in such a recording medium is the same as described above.

Further, according to another preferred embodiment of the present invention, the surface of the ink receiving layer can be smoothed to have a function as a glossy layer. Further, it is also possible to have a function as a glossy layer by smoothing the layer coated with the liquid containing the amphoteric polymer in the present invention. The smoothing action in this case may be the same as the above-described use or coating method of the coating liquid containing the component constituting the gloss layer.

Method for Manufacturing Recording Medium The recording medium according to the present invention can be manufactured by the following method. However, the scope of the present invention is not narrowed by the manufacturing method. A base paper is prepared by forming a sheet using the pulp raw material. A coating liquid is prepared by dissolving or dispersing the components forming the ink receiving layer in a suitable solvent such as water. Coat the base paper surface with a coating liquid. After the application, the ink is dried to form an ink receiving layer. Next, an amphoteric polymer layer is formed on the outermost surface layer of the ink receiving layer. The amphoteric polymer layer is formed by, for example, applying a liquid prepared by dispersing an amphoteric polymer in an appropriate solvent such as an organic solvent, drying the applied liquid, and further performing a calender treatment as necessary.

The coating is performed by a conventional method, and includes, for example, coating, impregnation, dipping and the like. Preferably, the coating liquid or the preparation liquid is applied using a coating machine having a coater head. The coater head can be appropriately selected according to the coating liquid, the base material, and the recording medium to be manufactured. Examples of the coater head include a blade coater, an air knife coater, a gravure coater, a transfer roll coater (such as a KCM coater and a gate roll coater), a lot coater, a bar coater, a hydro bar coater, a die coater, a bead coater, and a curtain coater. Conventional means can be used for heating and drying. Further, the temperature management can be controlled using a control device.

Recording Method According to another preferred embodiment of the present invention, a recording method for printing on a recording medium according to the present invention can be provided. The recording method comprises applying the ink composition to a recording medium according to the present invention at a transition temperature or lower, and then heating the recording medium at a transition temperature or higher. According to the recording method, there is an advantage that a recorded matter excellent in water resistance, moisture resistance, and light resistance can be provided.

EXAMPLES The following examples are disclosed in order to clarify the content of the present invention, but the scope of the present invention is not interpreted by limiting the scope of the examples.

Preparation of Substrate 20 parts by weight of NBKP (bleached kraft pulp of N-wood (coniferous tree)) and 80 parts by weight of LBKP (bleached kraft pulp of L-wood (hardwood)) were mixed with C.I. S.
It was beaten to 500 ml of F. The beating machine used a PFI mill of Kumagai. 10 parts by weight of clay, 0.3 part by weight of paper strength agent (trade name "Polystron" manufactured by Arakawa Chemical Industries) and 2 parts by weight of sizing agent ("Size Pine E" manufactured by Arakawa Chemical Industries) And 2 parts by weight of a sulfuric acid band, and the preparation (paper) was introduced into a fourdrinier paper machine to obtain a base material having a basis weight of 100 g / m ² by a conventional method.

Preparation of ink receiving layer liquid An ink receiving layer liquid was prepared according to the following composition. Silica gel (trade name X37B: manufactured by Tokuyama Corporation) 65% by weight Polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) 35% by weight

Coating of ink receiving layer The above ink receiving layer liquid was applied to the above substrate with a wire bar to form an ink receiving layer. The drying temperature was 120 ° C., and the coating amount was 20 g / m ² (at the time of drying).

Example 1 A recording medium was obtained by applying an amphoteric polymer layer having the following composition on a substrate provided with the above-mentioned ink receiving layer so as to have a coating amount of 5 g / m ^{2 by} a wire bar. N-dodecyl polymethacrylate 5% by weight n-hexane 95% by weight

Example 2 A gloss layer having the following composition was provided on a substrate provided with the ink receiving layer by transferring the gloss layer from a film. Thereafter, a recording sheet was obtained by further impregnating with an amphoteric polymer liquid having the same composition as in Example 1 for 10 seconds and drying. Colloidal silica (Snowtex XS: manufactured by Nissan Chemical) 90% by weight Polyvinyl alcohol (PVA105: manufactured by Kuraray Co., Ltd.) 10% by weight

Comparative Example 1 An ink receiving layer liquid was prepared according to the following composition.
A recording medium was obtained by forming an ink receiving layer by the same method as that for coating the ink receiving layer. Silica gel (X37B: manufactured by Tokuyama Co., Ltd.) 60% by weight Polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) 30% by weight Ink fixing agent (Sumitomo Chemical “Smilease Range 1001”) 10% by weight

[0058] Printing Evaluation Test The recording medium Example 1 to Comparative Example 1 was subjected to printing evaluation test. The printer is an inkjet printer PM77
Immediately before the print head of 0C (manufactured by Seiko Epson Corporation),
A device provided with an infrared heating device capable of heating to 100 ° C. in a non-contact manner was used. With the printer, standard color inks (black, magenta, cyan, and yellow: the standard ink compositions of the printer) were printed on a recording medium by inkjet recording, and the following evaluation was performed. In the printer, the weight of the ejected ink per dot was 0.040 μg, and the resolution was 360 dpi × 360 dpi.

Evaluation 1: The light-fast black ink composition, the magenta ink composition, the cyan ink composition, and the yellow ink composition were each solid printed (100% d) on a recording medium by the printer.
util). After printing, the film was dried in an environment of 23 ° C. and 50% RH for 24 hours or more. After that, the color difference ΔE * ab from the initial image was determined and evaluated using a Xe fade meter (Ci35A, Atlas). The measurement location was the image background. Irradiation was performed at a black panel temperature of 63 ° C., a relative humidity of 50%, 340 nm ultraviolet light, and an emissivity of 0.25 W /
m ² , 45 kJ / m ² .

Evaluation 2: The water-resistant black ink composition, the magenta ink composition, the cyan ink composition, and the yellow ink composition were each solid printed (100% d) on a recording medium by the printer.
util). After printing, after drying for 24 hours or more in an environment of 23 ° C. and 50% RH, one drop of tap water (approximately 0.1 g) was dropped on the print area and left for 24 hours. The degree of bleeding of the printed matter was visually evaluated according to the following evaluation criteria. The results were as shown in Table 1 below. Evaluation A: All four colors did not bleed. Evaluation B: Bleeding occurred in one color. Evaluation C: Bleeding occurred in two colors, but was practically acceptable. Evaluation D: Bleeding occurred in three or more colors, which was not practically acceptable.

Evaluation 3: The moisture-resistant printed image is a high-definition color digital standard image (ISO / J
The image name portrait (IS-SCID) (image recognition number N1, sample number 1) was printed. After printing, the printed matter is dried in an environment of 23 ° C. and 50% RH for 24 hours or more, and then left for three days in an environment of 40 ° C. and 85% RH to determine a color difference ΔE * ab from the initial image. evaluated. The measurement location was the background of the image. In the present invention, the color difference ΔE * ab is defined by the following equation. Color difference: ΔE * ab = [(ΔL *) ² + (Δa *) ² +
(Δb *) ² ] ^1/2 (where ΔL *, Δa *, and Δb * are L *, a *, and b * of the L * a * b * color system before and after the test. Means the difference between the coordinates).

Table 1 Example / Evaluation 1 2 3 Example 1 3.3 A 4.3 Example 2 2.6 B 5.5 Comparative Example 1 12.2 C 10.1

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA13 FC06 2H086 BA02 BA15 BA33 BA34 BA41 4J039 CA03 EA15 EA16 EA17 EA19 EA35 EA38 FA01 FA02 FA05 FA07 GA24

Claims (14)

[Claims] 1. A recording medium comprising a polymer which is reversibly hydrophobic at a transition temperature or lower and hydrophilic at a transition temperature or higher. 2. The recording medium according to claim 1, wherein said polymer is applied to a substrate. 3. The recording medium according to claim 1, comprising a substrate and an ink receiving layer, wherein the polymer is applied to the ink receiving layer. 4. The method according to claim 1, further comprising a glossy layer.
The recording medium according to any one of the above. 5. The method according to claim 1, wherein the polymer is applied to a glossy layer.
The recording medium according to claim 4. 6. The recording medium according to claim 1, wherein the transition temperature of the polymer is 25 ° C. or higher. 7. The recording medium according to claim 1, wherein said polymer is an acrylic acid long-chain alkyl ester represented by the following formula. Embedded image [In the above formula, R ¹ represents a linear or branched alkyl group having 0 to ² carbon atoms, and R ² represents a linear or branched alkyl group having 12 or more carbon atoms. represents, n represents represents a ¹⁰ 3 to 10 ^6] 8. The recording medium according to claim 1, wherein the polymer is obtained by polymerizing an acrylate monomer represented by the following formula. Embedded image [In the above formula, R ¹ represents a linear or branched alkyl group having 0 to ² carbon atoms, and R ² represents a linear or branched alkyl group having 12 or more carbon atoms. Represents] 9. The recording medium according to claim 1, wherein said polymer comprises a white pigment. 10. A type wherein the white pigment is selected from the group consisting of silica, calcium carbonate, alumina, boehmite, pseudoboehmite, aluminum hydroxide, calcium silicate, aluminum silicate, barium sulfate, white carbon, and zeolite. 10. The recording medium according to claim 9, which is a mixture of two or more kinds. 11. The recording medium according to claim 9, wherein the weight ratio of the polymer to the white pigment is from 100: 10 to 100: 2000. 12. A recording method for printing on a recording medium according to any one of claims 1 to 11, wherein the ink composition is applied to the recording medium at a transition temperature or lower, and thereafter, at a transition temperature or higher. Heating the recording medium with
Recording method. 13. The recording method according to claim 12, wherein an ink jet recording method is used in which droplets of the ink composition are ejected, and the droplets are attached to a recording medium to perform printing. 14. A printed matter printed by the recording method according to claim 12.