JPH09188066A - Ink jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the water resistance, fingerprint mark resistance and light resistance by incorporating polyvinylacetal resin and metallic oxide having two or more refractive indexes in an ink receiving layer as indispensable components in a recording medium having the layer provided on at least one surface of a base material. SOLUTION: In the recording medium used suitably for ink jet recording, an ink receiving layer contains polyvinylacetal resin and metallic oxide having two or more refractive indexes as indispensalbe components, and is prepared. In this case, the oxide is set so that the ratio of the content of the oxide to that of the resin in the layer is a range of 10/1 to 6/4. As the resin, aromatic polyvinylacetal resin is used. The degree of acetalization of the acetal resin is set to 0.5 to 40mol% Further, one of white pigment and titanium oxide is incorporated in the metallic oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium suitable for inkjet recording.

[0002]

2. Description of the Related Art Ink jet recording methods include various ink ejection methods such as an electrostatic suction method, a method in which a piezoelectric element is used to mechanically vibrate or displace ink, ink is heated to foam, and the pressure is used. Depending on the method
Small droplets of ink are generated and ejected, and part or all of them are attached to a recording material such as paper or a plastic film coated with an ink receiving layer for recording, but noise is reduced. , Has attracted attention as a method capable of high-speed printing and multicolor printing.

As the ink for the ink jet recording system, one mainly containing water is used from the viewpoint of safety and recording characteristics, and a polyhydric alcohol is used for preventing nozzle clogging and improving ejection stability. It is often the case that substances are added.

Recording media conventionally used for ink jet recording are described in JP-A-63-221077, JP-A-5-221112, JP-A-5-262028, JP-A-7-1828 and the like. As described above, a recording sheet provided with an ink receiving layer composed of acetal-modified polyvinyl alcohol, JP-A-55-1467.
A recording sheet composed of polyvinyl alcohol and polyvinylpyrrolidone as described in JP-A-86-86, a recording sheet mainly composed of polyvinylpyrrolidone as described in JP-B-3-29596, and JP-A-57-1.
A recording sheet comprising polyvinyl alcohol and polyvinyl butyral, as described in Japanese Patent No. 02391,
A recording sheet characterized by cross-linking a water-soluble resin as described in JP-A-58-89391, and an anti-fingerprint trace made of a polyester resin as described in JP-A-5-309956. Excellent recording sheet,
JP-A-62-83178 and JP-A-6-92011
A recording sheet characterized by containing fine silica particles as described in JP-A-57-087988 and a recording sheet characterized by containing an ultraviolet absorber as described in JP-A-57-087988. Has been proposed.

In recent years, with the improvement of the performance of ink jet recording apparatuses such as high speed recording and multicolor recording, more advanced and wide range characteristics have been required for ink jet recording media. That is, (1) the ink absorption capacity is high (the absorption capacity is large, the absorption time is fast), (2) the optical density of the dots is high, and the periphery of the dots is not blurred. (3) the dot shape is close to a perfect circle, The periphery is smooth (4) The characteristics of the recording sheet change little due to changes in temperature and humidity, and curling does not occur (5) Blocking does not occur (6) Images are stable for long-term storage and do not deteriorate That (especially,
(High temperature and high humidity environment) (7) Recording medium itself is stable for long-term storage and does not deteriorate (especially under high temperature and high humidity environment) (8) Fingerprints are hard to form (9) Ink receiving layer and recording area are water resistant (10) It is required to simultaneously satisfy the properties such as excellent adhesion between the ink receiving layer and the substrate.

Further, in the case of OHP recording sheets and the like, the recording medium itself is further excellent in transparency, that is, not only the film which is the base material but also the transparency of the ink receiving layer is excellent. Required.

On the other hand, even in a white substrate such as a white film or resin-coated paper, the transparency of the ink receiving layer is required to be excellent in order not to impair the whiteness and glossiness of the substrate itself. . In particular, regarding the glossiness, not only the glossiness of the unprinted portion is high, but also the glossiness of the printed portion is required. Further, due to the nature of the recording medium using the white base material, the chance of being left indoors or outdoors for a long time increases. That is, the light resistance of the recording portion is naturally required.

These various characteristics are often in a trade-off relationship, and it has been impossible to satisfy them at the same time with the conventionally known technology.

Further, high-speed recording, high image density,
As colorization progresses, deterioration of image quality due to defective ink fixing becomes a serious problem.

For example, as an example of a recording medium of the prior art, a recording medium provided with an ink receiving layer mainly containing polyvinylpyrrolidone described in Japanese Patent Publication No. 3-29596 has an ink absorbing capacity at room temperature and normal humidity. Although relatively good, the ink dries very slowly under high temperature and high humidity, and blocking is likely to occur between printed materials or a paper sandwiched between recording surfaces. In addition, the recording surface has a weak mechanical strength and is easily scratched.

The recording medium provided with an ink receiving layer composed of polyvinyl alcohol and polyvinyl pyrrolidone described in JP-A-55-146786 has good ink absorbability and fixability, but is It has poor water resistance and has a drawback that the ink receiving layer is easily peeled off when exposed to water.

The recording medium provided with an ink receiving layer composed of polyvinyl alcohol and polyvinyl butyral described in JP-A-57-102391 has poor compatibility of both resins and the transparency of the ink receiving layer itself. Has the drawback of being very bad.

The recording medium described in JP-A-60-220750, which is provided with an ink receiving layer mainly composed of polyvinyl alcohol, is good in terms of blocking resistance and mechanical strength of the recording surface. The image quality deteriorates when the recording medium itself is left in a high temperature and high humidity environment for a long time, and the ink absorption capacity decreases, and when the image is left in a high temperature and high humidity environment for a long time, the dots bleed and the image becomes sharp. There is a problem that

Japanese Unexamined Patent Publication (Kokai) No. 58-89391 proposes a recording medium provided with an ink receiving layer obtained by crosslinking a water-soluble resin. However, it has a drawback that it is excellent in water resistance but poor in ink absorption. Have.

The recording medium mainly composed of polyester resin described in JP-A-5-309956 is excellent in fingerprint traces, but is very bad in other aspects such as ink receptivity and image storability. It is not satisfactory because it has

As described in JP-A-63-221077, JP-A-5-221112, JP-A-5-262028, and JP-A-7-1828, polyvinyl acetal is used as an ink receiving layer. Although the problems of ink absorbency and water resistance are solved to some extent by using, the image sharpness maintaining characteristics are not particularly satisfactory when the recorded image is left in a high temperature and high humidity environment for a long time. Further, in a recording portion having a high recording density, ink cannot be sufficiently absorbed and beading occurs. For example, even if the ink is absorbed, it has a drawback that it takes a very long time for the ink to be fixed and dried, which is not satisfactory.

JP 62-83178 A, JP 6-A6
As described in JP-A-92011, by containing silica fine particles and colloidal silica, the ink absorption speed / absorption capacity, water resistance, and film resistance are good, but fingerprint resistance, blocking resistance, and recorded images are high temperature. It is not satisfactory in terms of image sharpness maintenance characteristics when left for a long time in a high humidity environment.

As described in JP-A-57-087988, by containing an ultraviolet absorber, the light resistance is good, but the fingerprint resistance, the ink fixing property, the ink absorption capacity, and the recorded image are high in temperature. It is not satisfactory in terms of maintaining image sharpness when left for a long time in a high humidity environment.

[0019]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording medium which simultaneously satisfies the above-mentioned various properties in a well-balanced manner. In particular, the recording medium itself has water resistance, fingerprint resistance, light resistance and ink resistance. Absorption capacity, ink fixability, anti-blocking, adhesion between the ink receiving layer and the substrate, transparency of the ink receiving layer that is particularly noticeable when a transparent substrate is used,
The purpose of the present invention is to provide a recording medium having no problem in practical use in terms of glossiness when using a white base material.

[0020]

The present inventors have developed a recording paper suitable for ink jet recording, a transparency film for an overhead projector (OHP), and a glossy film for indoor and outdoor viewing. A recording medium coated with the composition has extremely excellent water resistance, light resistance, fingerprint resistance, ink absorption capacity, ink fixability, blocking resistance, and adhesion between the ink receiving layer and the substrate. In addition, the dots are clear and sharp, the image quality is excellent, the change in performance is small even with changes in environmental conditions such as temperature and humidity, and the transparency when using a transparent substrate is excellent, and white. Numerous effects such as high glossiness in the printed area can be realized without causing the adverse effects such as deterioration of whiteness and glossiness when using white substrate such as film / resin coated paper. It found, which was accomplished the present invention, the above object is achieved by the following present invention.

That is, the present invention provides a recording medium comprising an ink receiving layer provided on at least one surface of a substrate, wherein the ink receiving layer comprises (a) a polyvinyl acetal resin (b) a metal having a refractive index of 2 or more. The present invention proposes an inkjet recording medium characterized by containing an oxide as an essential component, the content of the metal oxide having a refractive index of 2 or more as described in (b) above in the ink receiving layer, and The content of the polyvinyl acetal resin described in (a) in the ink receiving layer is (a) / (b) = 10/1.
To 6/4, the polyvinyl acetal resin (a) is an aromatic polyvinyl acetal resin, and the degree of acetalization of the polyvinyl acetal resin (a) is 0.5 to 40 mol%. That the metal oxide having a refractive index of 2 or more in (b) is a white pigment, and the metal oxide having a refractive index of 2 or more in (b) is at least one of titanium oxide, cerium oxide, and zinc oxide. 1
Including types, and the base material is a plastic film.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments.

The polyvinyl acetal resin as the first compound used in the present invention is a resin which can be obtained by condensation reaction of polyvinyl alcohol (hereinafter abbreviated as PVA) with an aldehyde to form an acetal. For this acetalization, known methods such as a precipitation method using water as a catalyst in the presence of an acid catalyst and a dissolution method using a solvent such as alcohol can be used. Using a polyvinyl acetate resin as a raw material, saponification and acetalization can be performed in parallel to obtain a polyvinyl acetal resin.

The PVA used in the present invention means vinyl acetate polymer or vinyl acetate and other copolymerizable monomers such as ethylene, propylene and vinyl chloride.
A copolymer with (meth) acrylic acid, an ester thereof or the like is obtained by an acid saponification method or an alkali saponification method. The PVA thus obtained preferably has a saponification degree of about 75 to 99% and a polymerization degree of 500 to 3500, but is not limited to this range. . Any of the above various saponification and polymerization degrees can be used alone or as a mixture. Further, the PVA as described above may be a modified PVA modified with various modifiers during the production of the raw material or after saponification, such as cation-modified PVA and anion-modified PVA.

As the compound for addition and / or condensation reaction with PVA as mentioned above, any of the compounds as mentioned above can be used, but the aldehyde compound is particularly preferable in the present invention. Aldehyde compounds include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, isopropylaldehyde, valeraldehyde, isovaleraldehyde and other saturated aliphatic aldehydes: benzaldehyde, o-, m- or p-tolualdehyde, benzylaldehyde, Salicylaldehyde, cinnamaldehyde,
Aromatic aldehydes such as α- or β-naphthaldehyde: Heterocyclic aldehydes such as furfural: Aliphatic unsaturated aldehydes such as acrolein, crotonaldehyde, propiol aldehyde, hexenal, heptenal: glyoxal, succindialdehyde, glutardialdehyde, Aliphatic dialdehydes such as adipodialdehyde, piperine dialdehyde, suberin dialdehyde, sebacin dialdehyde and the like can be mentioned.

Particularly preferable as such aldehydes are aliphatic aldehydes such as isobutyraldehyde and isopropylaldehyde, and aromatic aldehydes such as benzaldehyde and benzylaldehyde.

The degree of modification of PVA by the compound having reactivity with the hydroxyl group of PVA as described above, the so-called acetalization degree, is the degree of saponification of PVA, the degree of polymerization, the degree of hydrophilicity and hydrophobicity of PVA and the modifier used. Furthermore, modified PV, which changes depending on the performance required for the recording material, etc.
A is such that the hydrophilicity is not excessively lost, and is 0.5 to 40.
It is not more than mol%, preferably not more than 3 to 20 mol%. When the modification degree is less than 0.5 mol, unmodified PV
Compared with A, the effect of improving the performance is insufficient, which is not preferable. If it exceeds 40 mol%, the water resistance of the ink receiving layer will be good, but the ink absorbency will be poor.

Next, the metal oxide having a refractive index of 2 or more, which is the second compound used in the present invention, includes titanium oxide, chromium oxide, manganese oxide, iron oxide, nickel oxide, monovalent copper oxide, and 2 Valent copper oxide, zinc oxide, zirconium oxide, niobium oxide, cadmium oxide, tin oxide, antimony oxide, cerium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, mercury oxide, oxide salt, Examples include, but are not limited to, bismuth oxide, sodium oxide, plutonium oxide, and the like.

The particle size of these metal oxides is 1 nm.
˜20 μm in size can be used, but 1 nm to 400 nm as long as the transparency of the ink receiving layer is not impaired.
The size of is preferable.

Among the above metal oxides having a refractive index of 2 or more, titanium oxide, cerium oxide and zinc oxide are more preferable in consideration of safety.

These metal oxides having a refractive index of 2 or more may be contained in the ink receiving layer, or may be provided as an ultraviolet shielding layer on the outermost surface of the ink receiving layer.

When the refractive index of the metal oxide is less than 2, it cannot exert a sufficient effect of shielding ultraviolet rays and cannot serve as a light resistance improving substance.

When (a) the polyvinyl acetal resin in the present invention is mixed with (b) the metal oxide having a refractive index of 2 or more, the polyvinyl acetal resin is (a) / (b) = 10.
When it is more than / 1, the effect of adding a metal oxide having a refractive index of 2 or more cannot be obtained, and particularly, sufficient effects cannot be obtained in terms of light resistance, blocking property and ink fixing property.

Further, the metal oxide having a refractive index of 2 or more is (a)
When / (b) = 6/4 or more, the ink absorptivity is lowered, and the solid uniformity and the boundary blur between different colors are particularly deteriorated. Furthermore, it is not satisfactory in terms of fingerprint resistance, ink fixability, adhesion between the ink receiving layer and the substrate, and transparency. In addition, a sufficient effect cannot be obtained in terms of glossiness when a white base material is used.

When a transparent substrate is used as the recording medium of the present invention, the haze degree is 10% or less, preferably 5%.
% Or less is preferable. When a white base material is used, it is preferable that the gloss reduction rate is 20% or less, preferably 10% or less before and after the ink receiving layer is provided. A cationic compound may be further contained for the purpose of improving image storability. The cationic compound is not particularly limited as long as it contains a cationic moiety in the molecule.

For example, quaternary ammonium salt-type cationic surfactants such as monoalkylammonium chloride, dialkylammonium chloride, tetramethylammonium chloride, trimethylphenylammonium chloride and ethylene oxide-added ammonium chloride, or amine salt-type cations. It may be an amphoteric surfactant such as an alkyl betaine containing a cationic moiety, an imidazolium betaine, and an alanine-based surfactant.

As the polymer or oligomer, a cation-modified polyacrylamide, a copolymer of acrylamide and a cationic monomer, polyallylamine, polyamine sulfone, polyvinylamine,
Examples thereof include polyethyleneimine, polyamide-epichlorohydrin resin, polyvinylpyridinium halide and the like.

Further, a vinylpyrrolidone-based monomer alone or a copolymer with another general monomer, a vinyloxazolidone-based monomer alone or a copolymer with another general monomer, a vinylimidazole-based monomer Examples thereof include a single substance or a copolymer with other general monomers.

Examples of the above-mentioned general monomers include methacrylate, acrylate, acrylonitrile, vinyl ether, vinyl acetate, ethylene and styrene. The above cationic compounds are preferably used, but they may be used alone or in combination of two or more, and a low molecular weight cationic substance and a high molecular weight cationic substance may be used in combination. Of course, it is not limited to these.

Of course, in the constitution according to the present invention, the above-mentioned cationic compound is not an essential component, but merely shows an auxiliary role.

Further, as means for adjusting the hydrophilicity of the ink receiving layer, methylolated melamine, methylolated urea,
A cross-linking agent may be included, such as, but not limited to, methylolated hydroxypropylene urea and isocyanate.

Further, various additives may be used in combination in the composition of the ink receiving layer within a range not hindering achievement of the object of the present invention.

Specific examples of the additives include various surfactants, various fillers, dye fixing agents (waterproofing agents), defoamers, antioxidants, optical brighteners, dispersants, viscosity modifiers, p.
Examples include H regulators, antifungal agents, plasticizers, and the like. These additives may be arbitrarily selected from conventionally known compounds according to the purpose.

The base material of the recording medium used in the present invention includes high-quality paper, medium-quality paper, art paper, bond paper, recycled paper, baryta paper, cast coated paper, cardboard paper, resin coated paper, and the like. Polyethylene terephthalate, diacetate, triacetate, cellophane, celluloid, polycarbonate, polyimide, polyvinyl chloride,
A film or plate made of plastic such as polyvinylidene chloride, polyacrylate, polyethylene or polypropylene, a glass plate, or a cloth such as cotton, rayon, acrylic, silk or polyester can be used, but of course is not limited to these. .

The surface of the base material may be a smooth surface, unevenness, transparent, semi-transparent or opaque. Further, two or more kinds of these base materials may be bonded to each other.

Further, a mat layer, a release adhesive layer, etc. may be provided on the side opposite to the printing surface.

After printing, an adhesive layer or the like may be provided on the printed surface.

It is appropriately selected from the above-mentioned base materials according to the recording purpose of the recording medium, the use of the recorded image, or various conditions such as adhesion to the composition coated on the recording medium.

In preparing the recording medium of the present invention, first, the above composition, if necessary together with other additives, are added.
A coating solution is prepared by dissolving or dispersing in water or alcohol, polyhydric alcohol, or other appropriate organic solvent.

The obtained coating liquid is applied, for example, to a roll coater method, a blade coater method, an air knife coater method, a gate roll coater method, a bar coater method, a size press method, a spray coat method, a gravure coater method, a curtain coater method, etc. To coat the surface of the substrate. After that, it is dried using, for example, a hot-air drying oven or a heating drum to obtain the recording medium of the present invention. Further, if necessary, a super calendar treatment or the like may be performed to smooth the ink receiving layer or increase the surface strength.

The total coating amount of the ink receiving layer is 0.2 to 50 g / m ² , more preferably 1 to 30 g / m 2.
It is within the range of ² . Further, when the coating amount is less than 0.2 g / m ² , there is no effect in terms of the color developability of the paint, the ink absorption capacity, and the ink fixability, as compared with the case where the ink receiving layer is not provided, On the other hand, when the amount is more than 50 g / m ² , curling particularly under low temperature and low humidity environment is significantly unfavorable. When the coating amount is expressed by thickness, the coating amount is preferably in the range of 0.5 to 50 μm.

Known inks can be used as the ink itself when ink jet recording is performed on the recording medium described above.

As the recording agent, a direct dye, an acid dye, a basic dye, a reactive dye, a water-soluble dye represented by an edible dye, a dispersible dye and a pigment can be used.

Such water-soluble dyes or dispersible dyes and pigments are generally used in conventional inks in an amount of about 0.
It is used in a proportion of 1 to 20% by weight, and the proportion may be the same in the present invention.

The solvent used in the aqueous ink used in the present invention is water or a mixed solvent of water and a water-soluble organic solvent,
A particularly preferable solvent is a mixed solvent of water, a water-soluble organic solvent and a water-soluble organic solvent containing a polyhydric alcohol having an ink drying preventing effect.

The method for recording by applying the above-mentioned ink to the above-mentioned recording medium is preferably an ink jet recording method, and this method effectively separates the ink from the nozzle to form the ink on the recording medium. Any method may be used as long as it can add

Particularly, in the method described in Japanese Patent Laid-Open No. 54-59936, the ink subjected to the action of thermal energy causes a rapid volume change, and the action force due to this state change ejects the ink from the nozzle. The inkjet method can be effectively used.

[0058]

The present invention will be described in more detail with reference to the following examples. In the following description, “parts” or “%” is based on weight unless otherwise specified.

Examples 1 to 28 (Comparative Examples 1 to 14) Table 1 shows the type of polyvinyl acetal resin, the type of metal oxide having a refractive index of 2 or more, and the mixing ratio.

After the coating liquids mixed and adjusted as shown in Tables 1 and 2 were applied to the base materials used in each of Examples and Comparative Examples using a wire bar so that the coating thickness after drying was 10 μm. The recording medium of the present invention and the recording medium for comparison were prepared by drying at 120 ° C. for 5 minutes.

A bubble jet color printer BJC-600 manufactured by Canon Inc. was used as a recording method on the recording medium. The printing mode was an OHP sheet mode.

[0062]

[Table 1]

[0063]

[Table 2] << List of Substrates Used >> Transparent PET: A4100 manufactured by Toyobo Co., Ltd. (without easy adhesion layer) White PET: I.P. C. I. Made by Melinex 339 (100 μm) Cast paper: Gojo Paper Co., Ltd. Broadcast resin coated paper: Gojo Paper Co., Ltd. RC Gloria Manila The following items were evaluated for the obtained color print samples.

The evaluation results are shown in Tables 3 and 4.

The transparent substrate was evaluated by projecting it with a transmission type projector M4000 (manufactured by Sumitomo 3M Ltd.) and evaluating the projected image.

The image density is measured by using a transmission densitometer TR524 manufactured by Macbeth for those using a transparent substrate, and a reflection densitometer RD914 manufactured by Macbeth is used for those other than the transparent substrate. It was measured using.

[0067]

[Table 3]

[0068]

[Table 4] << Evaluation Items >> (1) Transparency 5 points were measured with a direct reading haze meter (manufactured by Toyo Seiki) and averaged. (Implemented only when the substrate is a transparent substrate)

(2) Blocking resistance 15 after recording with full dots of 2 colors each of yellow, cyan and magenta in an environment of 30 ° C./80% RH
After a lapse of minutes, Canon PB PAPER was interleaved on the recording surface, and then sealed in a clear pocket file (made by Lion, polypropylene film), 40 g / cm for 1 hour.
^The recorded image was saved under the pressure of ² . At this time, it was judged whether the film and the paper could be easily separated.

The case where it could be easily peeled was marked with ◯, the ink-receiving layer which could not be peeled off was transferred to the paper, or the part of the paper which remained adhered to the recording surface was marked with x, and the middle one was marked with Δ. .

(3) Anti-fingerprint trace A sweaty fingertip was pressed against the recording surface, and then wiped off with a cloth of 100% cotton, and visually judged.

The fingerprint was wiped off, the fingerprint was wiped off and remained, x was given, and the one which could not be said was marked with Δ.

(4) Ink fixing property In an environment of 30 ° C./80% RH, ink is printed when the recorded image is touched with a finger after recording with full dots of two colors of yellow, cyan and magenta. It was judged whether or not was taken into the inside of the ink receiving layer and did not adhere to the finger. The case where the finger no longer adheres to the finger within 5 minutes is indicated by O, the case within 10 is indicated by Δ, and the case after 10 minutes has elapsed is indicated by X.

(5) Ink absorption amount In an environment of 30 ° C./80% RH, when full dots of three colors each of yellow, cyan and magenta are recorded, the solid recording portion is uniform regardless of the recording density. When there is no bleeding with the boundary between different colors, ◎: When recording with full dots of 2 colors each of yellow, cyan and magenta under the same environment, the solid recording area is uniform regardless of the recording density.
The case where the bleeding with the different color boundary portion did not occur was evaluated as ◯, and the other cases were evaluated as x.

The recorded image is an image in which yellow recording portions are provided on both sides of a full-dot recording portion for each of three colors of yellow, cyan, and magenta or two colors.

(6) Water resistance After 1 hour of recording, the recorded medium was immersed in a tray containing water for 10 seconds, pulled up, and then wiped with a 100% cotton cloth to visually evaluate it.

The recorded images are black, cyan, magenta,
Yellow, red, green and blue squares (3 cm
X 3 cm) was recorded.

◯: No remarkable image deterioration was observed
The image that was found to be the image before the water resistance test in which the ink had flowed out was evaluated as Δ, the ink receiving layer had melted out, and the image that did not melt but was significantly different from the image before the water resistance test was evaluated as x. .

(7) Image Quality Visually, the solid uniformity and the point of bleeding between different color boundaries were evaluated.

As a recorded image, horizontal stripe patterns (2 cm × 15 cm / 1 line) of black, cyan, magenta, yellow, red, green and blue were recorded.

Good solid uniformity without color unevenness such as beading and no bleeding at the different color boundary portion, ○, poor uniformity of solid due to color unevenness such as beading. When the image quality was remarkably poor such as bleeding, x was given, and when the image quality was medium, it was given as Δ.

(8) Gloss Using a digital variable angle gloss meter UVG-5D (manufactured by Suga Test Instruments Co., Ltd.), 5 points of specular gloss of 20 degrees and 75 degrees were measured for both printed and unprinted areas. The average value was calculated. (Other than the transparent substrate) The recorded image recorded squares (3 cm x 3 cm) of black, cyan, magenta and yellow.

(9) Adhesion between ink receiving layer and base material Vinyl tape (Nitto Denko, No. 21, 19 mm)
Width) was adhered to the recording surface, and the peeling-off ink receiving layer having no problem was marked with ◯, and the peeled ink receiving layer was marked with ×.

(10) Light resistance 6 using an Atlas fade meter, Ci-35
The image densities of black, cyan, magenta, and yellow after 0 hours were measured at 5 points each to obtain an average value, which was compared with the image density measured before the light resistance test. When the residual image density is 80% or more, Those with 50% or less were marked with x, and those other than that were marked with Δ.

[0085]

As described above, according to the present invention, light resistance and fingerprint resistance are excellent, ink absorption is excellent, ink absorption is large, dots are clear, and optical density is high.
High-definition image formation, excellent blocking resistance,
The ink receiving layer and the printed part are water-resistant, the transparency of the recording medium is excellent when a transparent substrate is used, and the gloss when a white substrate is used is high regardless of the printed or unprinted part. Thus, it has become possible to supply a recording medium that has an ideal performance requirement that is excellent in the adhesion between the ink receiving layer and the substrate.

Claims (8)

[Claims] 1. A recording medium comprising an ink receiving layer provided on at least one surface of a substrate, wherein the ink receiving layer essentially comprises (a) a polyvinyl acetal resin (b) a metal oxide having a refractive index of 2 or more. An ink jet recording medium, characterized in that it is contained as a component. 2. The content of the metal oxide having a refractive index of 2 or more described in (b) above in the ink receiving layer and the content of the polyvinyl acetal resin described in (a) above in the ink receiving layer are: The inkjet recording medium according to claim 1, wherein (a) / (b) = 10/1 to 6/4. 3. The ink jet recording medium according to claim 1, wherein the polyvinyl acetal resin (a) is an aromatic polyvinyl acetal resin. 4. The inkjet recording medium according to claim 1, wherein the polyvinyl acetal resin (a) has an acetalization degree of 0.5 to 40 mol%. 5. The inkjet recording medium according to claim 1, wherein the metal oxide having a refractive index of 2 or more in (b) is a white pigment. 6. The inkjet recording medium according to claim 1, wherein the metal oxide having a refractive index of 2 or more in (b) contains at least one of titanium oxide, cerium oxide, and zinc oxide. 7. The inkjet recording medium according to claim 1, wherein the substrate is a plastic film. 8. The inkjet recording medium according to claim 7, wherein the substrate has a white gloss.