JPH10129112A - Inkjet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent ink receptivity, drying property, fixing property, dot reproducibility, etc., good ink coloring property, excellent black reproducibility, and ink receptive layer. Film strength,
Provided is an ink jet recording sheet which has good water resistance and gloss, and further suppresses ink bleeding and changes over time after printing. SOLUTION: On at least one side of a base sheet, 100 parts by weight of aluminum oxide fine particles of γ-type crystal form having an average particle diameter of 200 nm or less are partially saponified polyvinyl alcohol having a degree of polymerization of 1000 or more and a degree of saponification of 80 to 95 mol%. An ink-jet recording sheet comprising an ink receiving layer bound by 7 to 35 parts by weight of a binder containing:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet in which an ink receiving layer recordable by an ink jet printer is formed on at least one side of a base sheet. In addition to excellent strength, ink receptivity, drying properties, fixability, printability such as dot reproducibility, ink color development, black reproducibility, water resistance, weather resistance, etc. are good, and ink bleeding and aging after printing The present invention relates to an inkjet recording sheet in which a change is suppressed.

[0002]

2. Description of the Related Art In ink jet recording, ink is ejected from a nozzle to form minute droplets, which are attached to a base material such as paper as pixels in accordance with an electric input signal to form characters,
This is a recording method for forming figures, image patterns, and the like, and has features such as low noise, high resolution, and high-speed recording. An inkjet printer for inkjet recording only needs to include a printer head and an ink cartridge as components necessary for printing, and does not require a heating roller or a photosensitive drum for fixing ink.
Inkjet printers are small and inexpensive, and can easily print out color images simply by adding heads. Inkjet recording is used for printing on personal computers, word processors, etc. because of these excellent features.
Recently, application to various output devices such as a copying machine, a facsimile, and a plotter has been attempted. As a recording medium in ink jet recording, not only paper but also cloth, glass, synthetic resin, and the like are being studied.

[0003] In particular, a synthetic resin sheet generally has a better balance of heat resistance, dimensional stability, rigidity, etc., and satisfies requirements of transparency, durability, etc., as compared with other recording media (recording sheets). It is easy to select the material. On the other hand, according to the inkjet recording, a clear pattern can be obtained, and color printing (multicoloring) is easy. Therefore, if the synthetic resin sheet can be used as a recording medium for inkjet recording, it can be applied to various application fields. For example, overhead projector (OHP)
A transparent synthetic resin sheet such as a polyester sheet is used as the base paper for printing, but if this base paper can be used as a recording sheet, various conferences, conferences, lectures, briefing sessions, product promotion, etc. Can contribute to the expansion of the use of OHP. Even if it is a synthetic resin sheet base material with low transparency, if a clear pattern or color image can be formed by inkjet recording, recording,
It can be used as a material for explanations and advertisements.

However, the synthetic resin sheet generally has a problem that it is difficult to receive ink for ink jet recording. In an ink jet printer, ink that is difficult to dry is used in order to prevent the viscosity of the ink from increasing due to the drying of the ink in the jet nozzle portion and causing ejection failure. Ink jet inks generally consist of water-soluble dyes, binders, additives, and the like dissolved in water, so that drying and fixing of the ink on a hydrophobic synthetic resin sheet becomes poor. In order to perform printing with an ink jet printer, it is necessary to use a recording medium having a function of rapidly absorbing the moisture of the ink to dry and solidify it.

In order to use a synthetic resin sheet as a recording sheet suitable for ink-jet recording ink, it has been conventionally proposed to form an ink receiving layer exhibiting rapid water absorption on the synthetic resin sheet. ing. For example, (1) a sheet for inkjet recording in which an ink receiving layer containing polyvinylpyrrolidone is provided on the surface of a synthetic resin sheet having transparency (Japanese Patent Laid-Open No. 61-32788), (2) a transparent thermoplastic resin film A recording sheet provided with a transparent layer containing a water-soluble resin such as polyvinyl alcohol or gelatin and colloidal silica (JP-A-61-19389), and (3) an average particle size on a transparent plastic film. A recording sheet provided with a thin film of a water-soluble polymer containing ultrafine particles of 1 to 100 μm and fine particles of an average particle size of 1 to 20 μm (JP-A-61-280983); (4) particle size on a transparent film An overhead project coated with a transparent adhesive containing transparent fine particles (glass beads or synthetic resin spherical microbeads) of about 5 to 50 μm. Data for the film (JP-A-61-2449
No. 4) has been proposed.

However, a conventional swellable recording sheet using a water-soluble polymer such as polyvinylpyrrolidone as an ink receiving layer has an insufficient ink fixing ability.
There is a disadvantage that the sharpness of the image is reduced due to a change with time after printing. In addition, the swellable recording sheet has tackiness due to moisture absorption, and the handleability such as blocking decreases. Using a water-soluble polymer as a binder, inorganic fillers such as colloidal silica and alumina are mixed in a high ratio,
A conventional water-absorbing recording sheet having a porous ink-receiving layer has disadvantages such as poor transparency and a brittle and easily broken receiving layer. The ink receiving layer formed by binding and fixing synthetic resin spherical microbeads with a water-soluble polymer binder has good ink absorbency, but is inferior in ink fixability, has a lot of bleeding, and the receiving layer is fragile and easily broken. There are drawbacks.

On the other hand, ink jet recording sheets include:
It is required that an ink receiving layer having the following characteristics be formed on a base sheet. Excellent printability such as ink receptivity, absorption drying property, fixability, dot reproducibility, clear color of the ink, not discoloring over time, and excellent coating strength and water resistance , Even when stored in a laminated state, there is no blocking between the sheets, there is an appropriate spread of ink dots that can express the edge of the image sharply, there is no excessive bleeding, there is stickiness, There is no sticking of fingerprints. Furthermore, depending on the application field, many characteristics are required, for example, high transparency and glossiness. However, conventional inkjet recording sheets have not been able to sufficiently satisfy these required characteristics.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet recording sheet having an ink receiving layer formed on at least one side of a base sheet, and having an ink receiving property, a drying property, a fixing property, and dot reproduction. In addition to being excellent in printability such as reproducibility, good color development of ink, excellent in black reproducibility,
Good film strength, water resistance, gloss, etc. of the ink receiving layer,
It is still another object of the present invention to provide an ink jet recording sheet in which bleeding of ink and change over time after printing are suppressed.
Means for Solving the ProblemsThe present inventors have conducted intensive studies to overcome the problems of the prior art, and as a result, average particles bonded to at least one surface of a base sheet made of a synthetic resin sheet or the like by a binder containing a specific polyvinyl alcohol. Diameter 20
It has been found that the above object can be achieved by forming an ink receiving layer containing fine particles of aluminum oxide having a γ-type crystal form of 0 nm or less.

As the aluminum oxide, one having a γ-type crystal form is selected and used. Aluminum oxide preferably has an average primary particle diameter of 20 nm or less, but in a powder state, the primary particles are usually aggregated to form a secondary aggregate having a large particle diameter. The secondary aggregate is used after being finely pulverized so that the average particle diameter is 200 nm or less. Ink-jet recording having an ink-absorbing (water-absorbing) ink-receiving layer exhibiting excellent characteristics by combining such aluminum oxide fine particles in the γ-type crystal form with a binder containing polyvinyl alcohol to form an ink-receiving layer. Sheet can be obtained. That is, the inkjet recording sheet of the present invention has printability,
An ink-receiving sheet having very good ink coloring properties, black reproducibility, and water resistance and having extremely good gloss by an ink jet recording method can be obtained. This image receiving sheet can improve not only the weather resistance of the ink receiving layer but also the weather resistance of the printed ink.

The ink jet recording sheet needs to have an appropriate spread of the dot diameter of the ink. If the dot diameter is too small, white streaks are formed on the solid printed portion, and if the dot diameter is too large, boundary blur occurs, and the print becomes clear. Is lost. In order to adjust the dot diameter to an appropriate size, it is preferable to provide a thin surface treatment layer on the ink receiving layer of the present invention. When a surface treatment layer containing silica fine particles having a particle diameter of 10 to 100 nm bound by a water-soluble polymer binder is formed on the ink receiving layer, not only the adjustment of the dot diameter but also the transport damage due to the printer roll is caused. It has been found that the function of preventing printing unevenness is also fulfilled.
In addition, if an ink receiving layer is formed on one side of a base sheet and an adhesive layer is formed on the opposite side, a tack sheet that can be attached to various adherends can be obtained. The present invention has been completed based on these findings.

[0011]

According to the present invention, 100 parts by weight of aluminum oxide fine particles having a γ-type crystal form having an average particle diameter of 200 nm or less are provided on at least one surface of a substrate sheet. An ink jet recording sheet is provided, wherein an ink receiving layer bound by 7 to 35 parts by weight of a binder containing 80 to 95 mol% of partially saponified polyvinyl alcohol is formed.

Further, according to the present invention, the following preferred embodiments are provided. 1. The inkjet recording sheet described above, wherein the base sheet is a synthetic resin sheet. 2. Aluminum oxide fine particles having a γ-type crystal form
The above inkjet recording sheet, wherein the secondary particles have an average particle diameter of 20 nm or less, and the secondary aggregates are fine particles pulverized to an average particle diameter of 200 nm or less. 3. The above inkjet recording sheet, wherein the aluminum oxide fine particles in the γ-type crystal form are obtained by dispersing aluminum oxide particles in the γ-type crystal form in water and pulverizing the particles to an average particle diameter of 200 nm or less. 4. The above-mentioned inkjet recording sheet, wherein the γ-type crystal form aluminum oxide particles are pulverized in water using an ultrasonic homogenizer or a high-pressure homogenizer as a pulverizing means.

5. The binder containing polyvinyl alcohol is (1) a polymerization degree of 1000 or more and a saponification degree of 80 to 95.
The mole percentage of partially saponified polyvinyl alcohol is preferably 60 to 100% by weight, more preferably 65 to 99% by weight, still more preferably 75 to 95% by weight, and (2) completely saponified polyvinyl alcohol and silane-modified polyvinyl alcohol. Preferably, at least one polyvinyl alcohol selected from the group consisting of 0 to 40% by weight, more preferably 1 to 35% by weight, even more preferably 5 to 25% by weight.
The above-mentioned ink-jet recording sheet, which is a binder containing, by weight: 6. The ink jet recording sheet as described above, wherein the ink receiving layer contains a crosslinking agent having a reactivity with a hydroxyl group of polyvinyl alcohol. 7. The inkjet recording sheet according to the above, wherein the binder component in the ink receiving layer is crosslinked by the crosslinking agent.

8. The ink jet recording sheet described above, wherein a surface treatment layer containing silica fine particles having a particle diameter of 10 to 100 nm bonded by a water-soluble polymer binder is formed on the ink receiving layer. 9. The inkjet recording sheet as described above, wherein the water-soluble polymer binder is at least one polymer selected from the group consisting of polyvinyl alcohol and silane-modified polyvinyl alcohol. 10. The above ink jet recording sheet, wherein the binder component in the surface treatment layer is cross-linked by a cross-linking agent. 11. An ink receiving layer is formed on one surface of the base sheet, an adhesive layer is formed on the opposite surface, and if necessary, a release sheet is laminated on the adhesive layer for the ink jet recording. Sheet.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The base sheet used in the present invention is preferably formed of a synthetic resin having heat resistance, dimensional stability, rigidity and the like. Terephthalate), cellulose triacetate, polycarbonate, polyvinyl chloride, polypropylene, polyimide and the like (including films). The thickness of the base sheet is usually 20 to 2
It is about 50 μm. Among them, the thickness of 25 to 15
A 0 μm stretched polyethylene terephthalate film is particularly preferred. When preparing a photographic image receiving sheet, it is preferable to use a sheet provided with white hiding properties by kneading an extender such as titanium oxide into the above synthetic resin.
Further, a sheet material other than a synthetic resin sheet such as synthetic paper or coated paper can be used as the base sheet depending on the use. The base sheet may be provided with a primer layer or a corona discharge machining to improve the adhesiveness, if necessary, and then an ink receiving layer may be formed thereon. The ink receiving layer is usually formed on one side of the substrate sheet, but may be formed on both sides if desired. When the ink receiving layers are provided on both sides of the base sheet, a curl preventing effect can be obtained. An ink receiving layer may be formed on one side of the substrate sheet, and an anti-curl layer made of another material may be provided on the opposite side.

Aluminum Oxide Fine Particles In the present invention, aluminum oxide fine particles having an average particle diameter of 200 nm or less in a γ-type crystal form are used as main components of the ink receiving layer. Aluminum oxide has various crystal forms, and can be roughly classified into two crystal forms, which are thermodynamically stable α-form and unstable γ-form. The γ-type can be further divided into γ-group and δ-group when crystallographically classified. Among these, fine particles having a crystal form of the δ-group are more preferable. Aluminum oxide in the γ-type crystal form has an average primary particle diameter of 10 nm.
In the powder state, the primary particles generally form secondary aggregates, and can be reduced to several thousands to
The particle size increases to tens of thousands of nm. When such a large particle size aluminum oxide powder is used, not only the gloss of the ink receiving layer is lost, but also the film forming property is deteriorated.

The aluminum oxide powder in the γ-type crystal form is
It is preferable that the primary particle diameter is 20 nm or less.
Then, in order to obtain fine particles having an average particle diameter of 200 nm or less from the aluminum oxide powder in the form of the γ-type crystal which is a secondary aggregate, the fine particles are usually obtained by crushing means such as a bead mill, an ultrasonic homogenizer, and a high-pressure homogenizer. Crush until it becomes The average particle size of the aluminum oxide fine powder in the γ-type crystal form is preferably 150 nm or less,
More preferably, it is about 80 to 120 nm. The smaller the average particle diameter, the better the gloss of the ink receiving layer and the more appropriate the dot diameter of the ink. When the average particle diameter exceeds 200 nm, not only gloss is reduced, but also film formability is deteriorated, and many cracks are easily generated in the ink receiving layer.

Since the aluminum oxide in the γ-type crystal form is a hard crystal, contaminants from the pulverizing container easily enter in the pulverizing step, which may cause the ink receiving layer to be stained by coloring. Therefore, it is preferable to disperse aluminum oxide particles in the form of γ-type crystal in water and employ a pulverizing method using an ultrasonic homogenizer or a high-pressure homogenizer as a pulverizing means. Aluminum oxide fine particles in the γ-type crystal form are ink-absorbing, drying,
It is excellent in printability such as fixability, and by forming it into ultrafine particles, a recording sheet having excellent film-forming properties and gloss can be obtained.

Binder In the present invention, a binder containing a specific partially saponified polyvinyl alcohol as a main component is used as a binder for forming an ink receiving layer containing aluminum oxide fine particles in a γ-type crystal form. It is important to select a binder having good film-forming properties in order to use the aluminum oxide fine particles of the γ-type crystal form as the ink receiving layer. The present inventors have developed a specific polyvinyl alcohol (hereinafter referred to as PVA).
(Abbreviation) was used as a binder, and it was found that good film-forming properties could be obtained. That is, PVA
As a partially saponified P having a specific degree of polymerization and degree of saponification
VA has been found to be particularly preferred.

The ink receiving layer using partially saponified PVA as a binder is not sufficient in terms of transparency, and thus is not necessarily suitable for applications requiring a high degree of transparency such as OHP sheets. In addition, it is possible to provide a photographic image receiving sheet having very good ink coloring properties and water resistance and excellent gloss. This image receiving sheet can improve not only the weather resistance of the ink receiving layer but also the weather resistance of the printed ink. Therefore,
The ink jet recording sheet of the present invention can be used in a wide range of fields, such as recording, explanation, and advertising materials, by utilizing such features.

[0021] PVA is generally a polymer obtained by hydrolyzing (saponifying) polyvinyl acetate. Many types of PVA having different degrees of polymerization and saponification are commercially available. The film forming properties of PVA containing the aluminum oxide fine particles of the γ-type crystal form greatly vary depending on the degree of polymerization, the degree of saponification, and the amount of addition. In the present invention, partially saponified PVA having a degree of polymerization of 1,000 or more and a degree of saponification of 80 to 95 mol% is preferable because it exhibits excellent film-forming properties. When PVA having a low degree of polymerization or a low degree of saponification is used as a binder for aluminum oxide fine particles in a γ-type crystal form, the film-forming property is poor and cracks are easily generated. Also, when a large amount of completely saponified PVA is used as a binder, gelling is severe, and coating becomes difficult or impossible.

The binder is used in an amount of 7 to 35 parts by weight per 100 parts by weight of aluminum oxide fine particles in the γ-type crystal form.
Parts by weight, preferably 10 to 30 parts by weight. If the proportion of the binder is too small, the film-forming properties are poor and cracks are liable to occur. If the proportion is too large, the ink absorbency is reduced to cause ink bleeding and the printability is reduced. As the binder, the above partially saponified PVA can be used alone, but if desired, other binder components can be used in combination as small components, for the purpose of modifying the properties of the ink receiving layer. . For example, fully saponified PV
A and / or silane-modified PVA is preferably 40% by weight or less (0 to 40% by weight) based on the total amount of the binder,
More preferably 1 to 35% by weight, even more preferably 5 to
When the content is 25% by weight, the water resistance of the ink receiving layer can be further improved. The balance is partially saponified PVA. Completely saponified PVA and silane-modified P
VA has little effect on printability, but if its amount is too large, viscosity increases and gelation occurs, resulting in poor coatability.

The fully saponified PVA has a degree of saponification of more than 95 mol%, and the degree of saponification is usually
98 to 99 mol%, and almost all of the vinyl acetate groups in the polyvinyl acetate are saponified. Completely saponified PVA
Although many types having different degrees of polymerization are commercially available, in the present invention, those having a relatively high molecular weight having a degree of polymerization of 1000 or more are preferable because they improve the film-forming properties of the ink receiving layer. Silane-modified PVA is obtained by introducing a silanol group into PVA, and examples thereof include a polymer commercially available as an R-polymer from Kuraray Co., Ltd. In the present invention, those having a high degree of polymerization and relatively few silanol groups are suitable. A polymer having a low degree of polymerization has a poor film-forming property, while a polymer having a large amount of silanol groups has a severe increase in viscosity and gelation, and has poor coatability.

Ink Receiving Layer The ink jet recording sheet of the present invention contains, on at least one side of a base sheet, aluminum oxide fine particles of a γ-type crystal form having an average particle diameter of 200 nm or less and bound by a binder containing partially saponified PVA. The ink receiving layer is formed. The ink receiving layer of the present invention has γ
Since it contains aluminum oxide fine particles in the form of a pattern crystal, it is excellent in printability such as ink receptivity, drying property, fixing property, dot reproducibility, gloss and water resistance. Since the ink receiving layer of the present invention uses a binder containing partially saponified PVA, the ink receiving layer is excellent in film forming properties, and has very good printability, ink coloring properties, black reproducibility, water resistance, and gloss. An excellent photographic image receiving sheet can be provided. Furthermore, since the binder containing partially saponified PVA is used, not only the weather resistance of the ink receiving layer is excellent, but also the weather resistance of the printed ink is good. In addition, as long as the object of the present invention is not impaired, other general-purpose binders such as a water-soluble cellulose ether may be used in a small proportion together with the partially saponified PVA.

The ink receiving layer formed of the aluminum oxide fine powder of the γ-type crystal form and the PVA binder according to the present invention is different from the conventional swelling type ink receiving layer mainly containing a water-soluble polymer such as polyvinylpyrrolidone. Although the water resistance is excellent in comparison, the water resistance can be further improved by adding a crosslinking agent capable of reacting with the hydroxyl group of PVA and crosslinking the PVA. Examples of the crosslinking agent include melamine / formaldehyde resin, polyamide resin, epoxy resin, dialdehyde starch and the like. The proportion of the cross-linking agent can be appropriately determined depending on the type of the cross-linking agent, the desired degree of cross-linking, and the like.
Parts by weight. In order to form an ink receiving layer on a base sheet, usually, an ink receiving layer liquid (coating liquid) in which each component is uniformly dispersed or dissolved in water is prepared, and the coating liquid is applied to at least the base sheet. Apply to one side and dry. Water is used as a dispersion medium for the coating solution, but if desired,
Mix an organic solvent compatible with water such as alcohol,
It is possible to shorten the drying time.

A preferred method for preparing the coating solution is as follows. (1) An aqueous dispersion of aluminum oxide powder (secondary aggregate) in the form of γ-type crystal is prepared and pulverized by an ultrasonic homogenizer or a high-pressure homogenizer until the average particle diameter becomes 200 nm or less. Then, a slurry-like viscous dispersion is prepared. The concentration of the aluminum oxide fine powder in the dispersion is usually 5 to 40% by weight, preferably 10 to 40% by weight.
It is about 30% by weight. (2) Meanwhile, an aqueous binder solution is prepared. The aqueous solution of the binder containing partially saponified PVA is, for example, a PV containing 60 to 100% by weight of partially saponified PVA and 0 to 40% by weight of completely saponified PVA and / or silane-modified PVA.
A was added to the ion-exchanged water while stirring with a stirrer or the like, and was uniformly dispersed.
Stir to dissolve for ~ 3 hours. The concentration of PVA in the aqueous solution is usually about 3 to 20% by weight, preferably about 5 to 15% by weight. (3) An appropriate amount of the aqueous PVA solution thus prepared is added to a dispersion liquid of aluminum oxide fine particles having a γ-type crystal form, followed by stirring to prepare an ink receiving layer liquid. At this time, if necessary, other components such as a crosslinking agent are added, and further, if necessary, diluted with water to prepare a coating solution having a desired solid content concentration. The solid content concentration of the coating solution is usually 5 to 30% by weight,
Preferably, it is about 10 to 25% by weight.

As a means for coating the ink receiving layer liquid (coating liquid) on the surface of the base sheet, for example, a roll coater, an air knife coater, a bread coater, a rod coater, a bar coater, a comma coater or the like is used. A method of applying a liquid and drying with hot air can be adopted. The thickness of the ink receiving layer after drying is usually 5 to 50 μm, preferably 15 to 40 μm. If the thickness of the ink receiving layer is too thin, the ink absorbing ability becomes insufficient, and the printability is reduced.On the other hand, if the thickness is too large, there is a possibility that the coating film may be cracked, which is a factor of cost increase. Absent. When the coating solution contains a cross-linking agent, the PVA is cross-linked by adjusting the heating conditions in the drying step after coating.

Surface treatment layer The above-mentioned ink receiving layer can be used as it is. However, for the purpose of increasing gloss, adjusting the dot diameter of the ink, and preventing transport damage, etc., the surface treatment layer is used. It can be performed. The surface treatment is carried out on the ink receiving layer with a particle diameter of 10 to 1 bonded by a water-soluble polymer binder.
This is performed by forming a surface treatment layer containing silica fine particles of 00 nm. The silica fine particles used for the surface treatment layer are supplied as a colloid solution in which ultrafine particles of anhydrous silica are dispersed in water, and various grades having a particle diameter of 10 to 100 nm are available, for example, from Snowtex by Nissan Chemical Industries, Ltd. It is commercially available under the trade name. The particle size of the silica fine particles has a subtle effect on printability and prevention of transport damage due to a printer roll. As a general tendency, a particle having a small particle diameter increases gloss and has a small spread of a print dot diameter, and is effective in preventing transport damage, but tends to decrease the ink absorption speed. The required size of the print dot diameter varies depending on the type of printer and the number of print dots.If the number of print dots is small, a large dot diameter is required.If the number of print dots is large, a small dot diameter is required. Required. Therefore, it is preferable to select the particle diameter of the silica fine particles in consideration of the dot diameter, gloss, prevention of conveyance damage, ink absorption speed, and the like. If necessary, several types of silica fine particles having different particle diameters may be blended and used in order to balance various properties.

Examples of the water-soluble polymer binder include PVA, silane-modified PVA, water-soluble cellulose ether, sodium polyacrylate, polyvinylpyrrolidone,
Starch and its derivatives can be used.
VA and silane-modified PVA can be suitably used. The mixing ratio of the water-soluble polymer binder to 100 parts by weight of the silica fine particles is usually 1 to 100 parts by weight, preferably 5 to 30 parts by weight.
Parts by weight. If the amount of the water-soluble polymer binder is too small, the binder effect is weak, and the surface treatment agent layer becomes brittle. If the amount is too large, the ink absorption speed is reduced. Since the amount of the binder also affects the spread of the printing dot diameter, the blending number is set in consideration of this point.

In order to improve the water resistance of the surface treatment agent layer, a crosslinking agent capable of reacting with a hydroxyl group or a carboxylic acid group of the water-soluble polymer binder can be added. Examples of the crosslinking agent include melamine / formaldehyde resin, polyamide resin, epoxy resin, dialdehyde starch and the like. The use ratio of the crosslinking agent varies depending on the type of the water-soluble polymer binder and the crosslinking agent. In the case of PVA and silane-modified PVA, it is usually 1 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the polymer. Parts by weight.

The amount of the surface treatment agent applied has a large effect on the ink absorption speed, and if the amount is too large, the ink absorption speed tends to decrease. Therefore, it is desirable that the application amount be kept to the minimum necessary. Application amount is usually 0.01 to 1 g
/ M ² , preferably 0.03 to 0.3 g / m ² . If the amount is less than this, the effect of preventing damage to the conveyance and the effect of adjusting the dot diameter are insufficient. If the amount is too large, the ink absorption speed is reduced and the printability is reduced. As a method of applying the surface treatment agent, a surface treatment liquid of 0.1 to 5% by weight is prepared, applied on the ink receiving layer using a gravure coater or a Meyer bar, and dried with hot air. Means can be adopted.

Tack sheet By forming an adhesive layer on the surface of the ink jet recording sheet opposite to the surface on which the ink receiving layer is formed, a tack sheet can be attached to various adherends. The tack sheet having such a layer configuration can be used as various kinds of adhesive labels and seals. More specifically, after printing on the ink receiving layer, it can be attached to, for example, a postcard such as a New Year's card. As the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or the like can be appropriately selected depending on the application. When weather resistance is required, an acrylic pressure-sensitive adhesive is preferred. In the case where it is necessary to remove the adhesive once after attaching, a removable adhesive may be used. In order to protect the pressure-sensitive adhesive layer, a release sheet can be laminated on the pressure-sensitive adhesive layer. As the release sheet, a substrate on which a release layer such as silicone is formed on the surface of the substrate is used. As the base material of the release sheet, paper, a plastic sheet, a film, or the like is used. When the same type as the ink jet recording sheet base material is used, the occurrence of curling can be suppressed. For example, when polyester is used for the ink-jet recording sheet base material, it is desirable to use a polyester release sheet because the occurrence of curling can be suppressed when the release sheets are laminated via an adhesive layer.

[0033]

The present invention will now be described more specifically with reference to examples and comparative examples.

[Example 1] Aerosil Al ₂ O ₃ · C, an aluminum oxide powder having an average primary particle diameter of 20 nm or less in a γ-type crystal form [produced by Nippon Aerosil Co., Ltd.] 6
00 g was dispersed in 2400 g of ion-exchanged water in which 12 g of acetic acid was dissolved as a dispersion stabilizer, while stirring with a stirrer to prepare a 20% by weight dispersion. This solution was applied to a Gorin homogenizer 15MR- which is a high-pressure homogenizer.
700 kg / cm ^{2 with} 8TA type [Doei Shoji Co., Ltd.]
To obtain a milky-white, thriller-like, viscous dispersion. The average particle diameter of the inorganic fine particles dispersed in this dispersion was 95 nm. The average particle diameter was measured with a laser diffraction / scattering type particle size distribution analyzer LA-910 [manufactured by Horiba, Ltd.]. The composition of the coating liquid for the ink receiving layer is as follows. <Formulation A of coating liquid> Pulverized inorganic fine particles (average particle diameter 95 nm): 100 g (solid content) Aerosil Al ₂ O ₃ .C (γ-type aluminum oxide fine particles) Partially saponified polyvinyl alcohol ... ···· 15 g (solid content) PVA-217 (manufactured by Kuraray Co., Ltd.), polymerization degree 1700, saponification degree 88 mol% Melamine / formaldehyde resin (crosslinking agent) ··· 1.5 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid content concentration of 17% by weight The solution viscosity of the coating solution was 320 mPa · s (30 ° C.). there were.

On one side of a 100 μm-thick white polyester film (Melinex # 339, manufactured by ICI Japan Co., Ltd.), the coating liquid of Formulation A was dried to a coating thickness of 30 μm. It was applied with a comma coater and dried at 110 ° C. for 3 minutes to obtain an ink jet recording sheet having an ink receiving layer formed thereon. The ink receiving layer of this recording sheet has a very high gloss,
The film strength and water resistance were also good. As a result of performing a printing test using an inkjet printer MJ700V2C (manufactured by Seiko Epson Corporation), the ink receptivity,
Good drying and fixing properties, excellent dot reproducibility and black reproducibility, and no bleeding. However, the dot diameter of the ink was rather small, and white streaks were slightly observed in the solid printing portion, and slight transport damage due to the printer roll was also observed, but all were within a practically acceptable range. This recording sheet had good water resistance, and the sharpness of the image did not change with time.

[Example 2] <Formulation B of coating liquid> Pulverized inorganic fine particles (average particle diameter 95 nm) ... 100 g (solid content) Aerosil Al ₂ O ₃ · C (γ-type aluminum oxide fine particles) Saponified polyvinyl alcohol 25 g (solid content) PVA-235 (manufactured by Kuraray Co., Ltd.), degree of polymerization 3500, degree of saponification 88 mol% Melamine / formaldehyde resin (crosslinking agent) ... 2.5 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water ... adjusted to a solid content concentration of 15% by weight Coating solution The viscosity was 560 mPa · s (30 ° C.). Except for changing the kind and the number of parts of the partially saponified polyvinyl alcohol, and lowering the solid concentration for adjusting the solution viscosity, a coating solution of the formulation B was prepared in the same manner as in Example 1; Coating was performed in the same manner to obtain an ink jet recording sheet. The ink receiving layer of this recording sheet had a very high gloss, a good film strength and good water resistance. Inkjet printer MJ700V2
As a result of performing a printing test using C (manufactured by Seiko Epson Corporation), the ink receiving property, the drying property, and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no blur. However,
The dot diameter of the ink was rather small, and white streaks were slightly observed in the solid printing area, and slight transport damage due to the printer roll was also observed, but all were within a practically acceptable range. This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Example 3 <Formulation Formulation C of Coating Liquid> Pulverized inorganic fine particles (average particle diameter 95 nm): 100 g (solid content) Aerosil Al ₂ O ₃ .C (γ-type aluminum oxide fine particles) Saponified polyvinyl alcohol 18 g (solid content) PVA-235 (manufactured by Kuraray Co., Ltd.), degree of polymerization 3500, degree of saponification 88 mol% Silane-modified polyvinyl alcohol ... ····· 2 g (solid content) Kuraray R polymer R-1130 (manufactured by Kuraray Co., Ltd.), saponification degree 98 to 99 mol%, ion exchange water ··· The solution viscosity of the coating solution was adjusted to 450 mPa · s (30 ° C.). A coating liquid of formulation C was prepared in the same manner as in Example 1 except that silane-modified polyvinyl alcohol was used in combination with partially saponified polyvinyl alcohol as a binder, the number of blended portions was changed, and the solid content concentration was changed to adjust the solution viscosity. Then, coating was performed in the same manner as in Example 1 to obtain an inkjet recording sheet. The ink receiving layer of this recording sheet had a very high gloss, a good film strength and good water resistance. Inkjet printer MJ700V2C
As a result of performing a printing test with [Seiko Epson Corporation], the ink receiving property, the drying property and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. However, the dot diameter of the ink was rather small, and white streaks were slightly observed in the solid printing portion, and slight transport damage due to the printer roll was also observed, but all were within a practically acceptable range. This recording sheet has good water resistance, and
The sharpness of the image did not change with time.

Example 4 <Formulation D of Coating Solution> Pulverized inorganic fine particles (average particle diameter 95 nm): 100 g (solid content) Aerosil Al ₂ O ₃ .C (γ-type aluminum oxide fine particles) Saponified polyvinyl alcohol 18 g (solid content) PVA-235 (manufactured by Kuraray Co., Ltd.), degree of polymerization 3500, degree of saponification 88 mol% Completely saponified polyvinyl alcohol ... 2 g (solid content) PVA-117 (manufactured by Kuraray Co., Ltd.), polymerization degree 1700, saponification degree 98.5 mol% melamine / formaldehyde resin (crosslinking agent) 2 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid concentration of 16% by weight The solution viscosity of the coating solution is 530 mPa · s ( It was 0 ℃). A coating solution of Formulation D was prepared in the same manner as in Example 1 except that completely saponified polyvinyl alcohol was used in combination with partially saponified polyvinyl alcohol, the number of blended portions was changed, and the solid content concentration was changed to adjust the solution viscosity. It was prepared and coated in the same manner as in Example 1 to obtain an inkjet recording sheet. The ink receiving layer of this recording sheet had a very high gloss, a good film strength and good water resistance. A printing test was conducted with an ink jet printer MJ700V2C (manufactured by Seiko Epson Corporation). As a result, the ink receiving property, the drying property, and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. However, the dot diameter of the ink was rather small, and white streaks were slightly observed in the solid printing portion, and slight transport damage due to the printer roll was also observed, but all were within a practically acceptable range.
This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Example 5 A surface treatment liquid for surface-treating the ink receiving layer was prepared according to the following formulation, and was applied on the ink receiving layer of the ink jet recording sheet obtained in Example 1. <Blending formulation a of surface treatment liquid> Silica fine particles (particle size: 20 to 30 nm) ... 100 g (solid content) Snowtex ST-50 (Nissan Chemical Co., Ltd., colloid solution of ultrafine silica particles) , Solid content 48% by weight) Completely saponified polyvinyl alcohol 10 g (solid content) PVA-117 (manufactured by Kuraray Co., Ltd.), polymerization degree 1700, saponification degree 98.5 mol % Melamine / formaldehyde resin (crosslinking agent) 1 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water 1 solid content concentration 1 The solution viscosity of the surface treatment liquid was 15 mPa · s (30 ° C.). After applying a surface treatment liquid with a gravure coater on the ink receiving layer of the ink jet recording sheet obtained in Example 1 so as to have a solution application amount of about 10 g / m ² ,
After drying at 110 ° C. for 3 minutes, an ink jet recording sheet was obtained. The gloss of the ink-receiving layer on the surface of the recording sheet was further increased. Inkjet printer M
As a result of performing a printing test using J700V2C (manufactured by Seiko Epson Corporation), the ink receptivity, the drying property and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. In addition, the dot diameter of the ink became wide, no white streaks were observed in the solid printed portion, and no transport damage due to the printer roll was observed. This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Example 6 A solution application amount of about 1 was applied on the ink receiving layer of the ink jet recording sheet obtained in Example 2.
Example 5 with a gravure coater so as to be 0 g / m ²
Was applied and dried at 110 ° C. for 3 minutes to obtain an inkjet recording sheet. The gloss of the ink-receiving layer on the surface of the recording sheet was further increased. As a result of performing a printing test using an inkjet printer MJ700V2C (manufactured by Seiko Epson Corporation), the ink receiving property, the drying property, and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. In addition, the dot diameter of the ink became wide, no white streaks were observed in the solid printed portion, and no transport damage due to the printer roll was observed. This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Example 7 A surface treatment liquid for surface-treating the ink receiving layer was prepared according to the following formulation, and was applied onto the ink receiving layer of the ink jet recording sheet obtained in Example 3. <Formulation b of surface treatment liquid> Silica fine particles (particle diameter 70 to 100 nm) ... 100 g (solid content) Snowtex ST-ZL (manufactured by Nissan Chemical Co., Ltd., colloid solution of silica ultrafine particles, solid Silane-modified polyvinyl alcohol 10 g (solid content) Kuraray R polymer R-1130 (manufactured by Kuraray Co., Ltd.), saponification degree 98 to 99 mol% melamine / formaldehyde resin (Cross-linking agent) 1 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water ... adjusted to a solid content concentration of 1% by weight Surface treatment The solution viscosity of the liquid was 18 mPa · s (30 ° C.). After applying a surface treatment liquid with a gravure coater on the ink receiving layer of the ink jet recording sheet obtained in Example 3 so as to have a solution application amount of about 10 g / m ² ,
After drying at 110 ° C. for 3 minutes, an ink jet recording sheet was obtained. The gloss of the ink-receiving layer on the surface of the recording sheet was further increased. Inkjet printer M
As a result of performing a printing test using J700V2C (manufactured by Seiko Epson Corporation), the ink receptivity, the drying property and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. In addition, the dot diameter of the ink became wide, no white streaks were observed in the solid printed portion, and no transport damage due to the printer roll was observed. This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Example 8 A surface treatment liquid for surface-treating the ink receiving layer was prepared according to the following formulation, and was applied onto the ink receiving layer of the ink jet recording sheet obtained in Example 4. <Formulation c of surface treatment liquid> Silica fine particles (particle diameter 20 to 30 nm) ... 50 g (solid content) Snowtex ST-50 (manufactured by Nissan Chemical Industries, Ltd.) Silica fine particles (particle diameter 70 to 100 nm) 50 g (solid content) Snowtex ST-ZL (manufactured by Nissan Chemical Co., Ltd.) Silane-modified polyvinyl alcohol ... 10 g (solid content) Kuraray R Polymer R-1130 (Kuraray) Melamine / formaldehyde resin (crosslinking agent) 1 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Adjusted to a concentration of 1% by weight The solution viscosity of the surface treatment liquid was 20 mPa · s (30 ° C.). After applying a surface treatment liquid with a gravure coater on the ink receiving layer of the ink jet recording sheet obtained in Example 4 so as to have a solution application amount of about 10 g / m ² ,
After drying at 110 ° C. for 3 minutes, an ink jet recording sheet was obtained. The gloss of the ink-receiving layer on the surface of the recording sheet was further increased. Inkjet printer M
As a result of performing a printing test using J700V2C (manufactured by Seiko Epson Corporation), the ink receptivity, the drying property and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. In addition, the dot diameter of the ink became wide, no white streaks were observed in the solid printed portion, and no transport damage due to the printer roll was observed. This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Example 9 Aerosil Al ₂ O ₃ .C, an aluminum oxide powder having an average primary particle diameter of 20 nm or less in the γ-type crystal form [manufactured by Nippon Aerosil Co., Ltd.] 4
50 g was dispersed in 2550 g of ion-exchanged water in which 9 g of acetic acid was dissolved as a dispersion stabilizer by stirring with one stirrer.
A 5% by weight dispersion was prepared. This solution was subjected to a high pressure homogenizer, Gaulin homogenizer 15MR-8TA.
The mixture was pulverized at a pressure of 300 kg / cm ^{2 with a} mold [Doei Shoji Co., Ltd.] to obtain a milky white slurry-like viscous dispersion. The average particle size of the inorganic fine particles dispersed in this dispersion is
184 nm. The average particle diameter is measured by a laser diffraction / scattering particle size distribution analyzer LA-910 [Horiba Seisakusho Co., Ltd.]
Manufactured). The composition of the coating liquid for the ink receiving layer is as follows. <Formulation E of the coating liquid> ground inorganic fine particles (average particle diameter 184 nm) .... 100 g (solids) of Aerosil Al ₂ O ₃ · C (γ-type aluminum oxide particles) partially saponified polyvinyl alcohol .... 15 g (solid content) PVA-217 (manufactured by Kuraray Co., Ltd.), polymerization degree 1700, saponification degree 88 mol% Melamine / formaldehyde resin (crosslinking agent) 1.5 g ( Solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid content concentration of 13% by weight The solution viscosity of the coating solution is 280 mPa · s (30 ° C.). there were. A coating liquid of formulation E was prepared in the same manner as in Example 1 except that the average particle size of Aerosil Al ₂ O ₃ · C (γ-type aluminum oxide fine particles) after pulverization was different.
Was applied in the same manner as in Example 1 to obtain an ink jet recording sheet. The ink receiving layer of this recording sheet had slightly lower gloss, but also had good film strength and water resistance.
As a result of performing a printing test using an inkjet printer MJ700V2C (manufactured by Seiko Epson Corporation), the ink receiving property, the drying property, and the fixing property were good, the dot reproducibility and the black reproducibility were excellent, and there was no bleeding. However, the dot diameter of the ink was rather small, and white streaks were slightly observed in the solid printing portion, and slight transport damage due to the printer roll was also observed, but all were within a practically acceptable range.
This recording sheet had good water resistance, and the sharpness of the image did not change with time.

Comparative Example 1 A coating solution was prepared according to the following formulation. <Formulation Formulation F of Coating Liquid> Pulverized inorganic fine particles (average particle diameter: 95 nm): 100 g (solid content) Aerosil Al ₂ O ₃ .C (γ-type aluminum oxide fine particles) Partially saponified polyvinyl alcohol: 15 g (solid content) PVA-205 (manufactured by Kuraray Co., Ltd.), degree of polymerization 500, degree of saponification 88 mol% Melamine / formaldehyde resin (crosslinking agent) 1.5 g (solid Min) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid content concentration of 17% by weight The solution viscosity of the coating solution was 250 mPa · s (30 ° C.). Was. A coating solution was prepared and coated in the same manner as in Example 1 except that PVA-205 having a low degree of polymerization was used as the partially saponified polyvinyl alcohol. This coating liquid had poor film-forming properties, and when dried, the ink-receiving layer cracked and a good ink-receiving layer was not obtained. Therefore, evaluation of printability and the like was not performed.

Comparative Example 2 A coating solution was prepared according to the following formulation. Ground inorganic particulate <Formulation G of the coating solution> (average particle size 95 nm) · · · · 100 g (solids) of Aerosil Al ₂ O ₃ · C (γ-type aluminum oxide particles) silane-modified polyvinyl alcohol ----- ····· 15 g (solid content) Kuraray R polymer R-1130 [manufactured by Kuraray Co., Ltd.], saponification degree 98 to 99 mol% Melamine / formaldehyde resin (crosslinking agent) ··· 1.5 g (solid Min) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid concentration of 17% by weight Except that R-1130, which is a silane-modified polyvinyl alcohol, was used alone A coating solution was prepared in the same manner as in Example 1, and coating was attempted. However, this coating liquid caused a drastic increase in viscosity at the time of preparation, exhibited a gel state, and could not be applied. The solution viscosity of the coating solution could not be measured due to gelation. Therefore, evaluation of printability and the like was not performed.

Comparative Example 3 A coating solution was prepared according to the following formulation. <Formulation H of coating liquid> Pulverized inorganic fine particles (average particle diameter: 95 nm): 100 g (solid content) Aerosil Al ₂ O ₃ .C (γ-type aluminum oxide fine particles) Partially saponified polyvinyl alcohol ... 40 g (solid content) PVA-235 (manufactured by Kuraray Co., Ltd.), degree of polymerization 3500, degree of saponification 88 mol% Melamine / formaldehyde resin (crosslinking agent) 1.5 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid concentration of 14% by weight The solution viscosity of this coating solution is 250 mPa · s (30 ° C.).
Met. PV which is partially saponified polyvinyl alcohol
A coating solution was prepared and coated in the same manner as in Example 2 except that the number of A-235 was increased, to obtain a sheet for inkjet recording. The ink receiving layer of this recording sheet had a very high gloss, a good film strength and good water resistance. However, this recording sheet had insufficient ink absorbency, caused ink bleeding, and had poor printability.

Comparative Example 4 7.2 g of acetic acid was used as a dispersion stabilizer using 360 g of Aerosil Al ₂ O ₃ · C (manufactured by Nippon Aerosil Co., Ltd.), which is an aluminum oxide powder in the γ-type crystal form.
Was dissolved and dispersed in 2640 g of ion-exchanged water with a stirrer to prepare a 12% by weight dispersion. 300 kg of this solution was applied to a Gorin homogenizer 15MR-8TA type [Domoe Shoji Co., Ltd.] which is a high-pressure homogenizer.
/ Cm ² pressure to obtain a milky white slurry-like viscous dispersion. The average particle diameter of the inorganic fine particles dispersed in this dispersion was 272 nm. The average particle diameter was measured with a laser diffraction / scattering type particle size distribution analyzer LA-910 [manufactured by Horiba, Ltd.]. The composition of the coating liquid for the ink receiving layer is as follows. <Formulation Formulation I of Coating Solution> Pulverized inorganic fine particles (average particle size 272 nm): 100 g (solid content) Aerosil Al ₂ O ₃ · C (γ-type aluminum oxide fine particles) Partially saponified polyvinyl alcohol ... ····· 15 g (solid content) PVA-217 (manufactured by Kuraray Co., Ltd.), polymerization degree 1700, saponification degree 88 mol% Melamine / formaldehyde resin (crosslinking agent) ··· 1.5 g (solid content) Sumirez Resin 613 (manufactured by Sumitomo Chemical Co., Ltd.) Ion-exchanged water: adjusted to a solid concentration of 11% by weight The solution viscosity of the coating solution was 250 mPa · s (30 ° C.). A coating solution of Formulation I was prepared in the same manner as in Example 1 except that the average particle size of Aerosil AL ₂ O ₃ · C (γ-type aluminum oxide fine particles) after pulverization was different.
Was applied in the same manner as in Example 1 to obtain an ink jet recording sheet. The ink receiving layer of this recording sheet has not only poor gloss but also many large and small cracks in the receiving layer.
The film forming property was poor. Therefore, evaluation of printability and the like was not performed. Table 1 shows the measurement results of the properties.

[0048]

[Table 1]

<Measurement Method> (1) Dot diameter Using an inkjet printer MJ700V2C (manufactured by Seiko Epson Corporation), one dot of black ink was printed on a recording sheet by itself, and the diameter of the black ink dot (μ
m) was read and measured using a microscope (manufactured by Mitutoyo Corporation). (2) Gloss Using a digital gloss meter GP-60 (manufactured by Tokyo Denshoku Co., Ltd.), 60 ° specular gloss Gs (60) (%) was measured according to JIS Z8741 (method for measuring specular gloss). When a white polyester film is used as the base sheet, a high gloss can be visually sensed at a Gs (60) of 44% or more.

(3) Evaluation on Printing Evaluation on printing was performed by printing a printability evaluation pattern on a recording sheet using an inkjet printer MJ-700V2C manufactured by Seiko Epson Corporation. Ink receptivity (dryness) Immediately after printing, the solid printed portion was touched with a finger and evaluated according to the following criteria. ：: no ink adheres to finger, Δ: slight ink adheres to finger, ×: ink adheres to finger. Ink fixability After printing, paper was pressed on the ink receiving layer and allowed to stand, and evaluated according to the following criteria. ：: no change such as adhesion of ink to the paper surface or blurred image due to passage of time; ×: change such as adhesion of ink to the paper surface or blurred image due to passage of time. Dot Reproducibility The spread of the dots was observed under magnification with a microscope, and evaluated based on the following criteria. ：: The shape and size of the dots are constant and there is no feathering, etc. ×: The shape and size of the dots are undefined and there are feathering and the like. Bleeding Bleeding at the boundary of solid printing color and bleeding in the overprinted portion were observed and evaluated according to the following criteria. ：: no bleeding or small degree of bleeding; ×: bleeding observed. Change over time After printing, the stability of the image when left indoors for 6 months, or as an accelerated aging test, the stability of the image after standing one day in an atmosphere of 80% RH at 40 ° C. Was evaluated. ：: no change in image, ×: change is observed in image.

(4) Conveyed Scratches Printing was performed on a recording sheet (A-4 size) using an inkjet printer MJ700V2C (manufactured by Seiko Epson Corporation), and the presence or absence of printing unevenness generated by the printer roll was observed. Was evaluated. ：: No transport damage due to the printer roll was observed in the solid print area, Δ: Slight transport damage due to the printer roll was observed in the solid print area, ×: Transport damage due to the printer roll was observed in the solid print area. (5) Water resistance After printing on a recording sheet, the sheet was immersed in water for 3 hours, taken out and air-dried, and evaluated according to the following criteria. ：: No dissolution of the ink receiving layer and no dissolution of the ink. ×: Dissolution of the ink receiving layer and dissolution of the ink. (6) Black reproducibility Ink jet printer MJ800
A gray scale was printed with black ink for C (manufactured by Seiko Epson Corporation), and black reproducibility was evaluated according to the following criteria. ：: Real black is reproduced without browning, ×: Real black is not reproduced.

Example 10 An acrylic pressure-sensitive adhesive layer having a thickness of 20 μm was formed on a release-treated surface of a 75 μm-thick polyester release sheet whose surface was treated with a silicone-based release agent. On the other hand, an ink jet recording sheet was produced in the same manner as in Example 7, except that a 38 μm-thick white polyester film [Melinex # 339, manufactured by ICI Japan Ltd.] was used as the base sheet. . The pressure-sensitive adhesive layer of the release sheet and the surface of the ink jet recording sheet opposite to the surface on which the ink receiving layer was formed were attached to form a tack sheet. When a printing test similar to that of Example 7 was performed on this recording sheet, the same good results as those of Example 7 were obtained. Further, even when printing was performed with a printer, no adhesion of the adhesive to a printer roll or the like was observed.

[0053]

According to the present invention, there is provided an ink jet recording sheet having an ink receiving layer formed on at least one side of a base sheet, which is excellent in glossiness and strength of the ink receiving layer, and has an ink receiving property. Provided is an ink jet recording sheet which has good drying properties, fixability, dot reproducibility, black reproducibility, water resistance, etc., and is free from ink bleeding and changes over time after printing. In addition, by treating the surface of the ink receiving layer with a surface treating agent containing fine silica particles, it is possible to control the print dot diameter and to prevent transport damage due to the printer roll. The inkjet recording sheet of the present invention has a very good gloss and is particularly suitable for obtaining a photographic image receiving sheet having high print quality. An ink-receiving layer is formed on one side of the base sheet, and an adhesive layer is formed on the opposite side.If necessary, a tack sheet can be obtained by laminating a release sheet on the adhesive layer. can do.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshikazu Ito 2-3-3 Sekiguchi, Bunkyo-ku, Tokyo Inside Nichiban Co., Ltd. (72) Inventor Koji Mizuno 2-3-3 Sekiguchi 2-chome, Bunkyo-ku, Tokyo Nichiban (72) Inventor Hideo Tateno 2-3-3 Sekiguchi, Bunkyo-ku, Tokyo Nichiban Co., Ltd. (72) Inventor Hiroyuki Onishi 3-3-5, Yamato, Suwa-shi, Nagano Seiko Epson Corporation ( 72) Inventor Akio Owatari 3-5-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (72) Inventor Masaaki Itano 3-3-5 Yamato Suwa-city, Nagano Prefecture Seiko Epson Corporation

Claims (6)

[Claims] 1. A partially saponified polyvinyl oxide having a degree of polymerization of not less than 1000 and a degree of saponification of 80 to 95 mol%, wherein at least one surface of a base sheet has 100 parts by weight of aluminum oxide fine particles of γ-type crystal form having an average particle diameter of not more than 200 nm. An ink jet recording sheet comprising an ink receiving layer bound by 7 to 35 parts by weight of a binder containing alcohol. 2. The aluminum oxide fine particles of the γ-type crystal form have an average primary particle diameter of 20 nm or less, and a secondary aggregate thereof has an average particle diameter of 200 nm.
2. The ink jet recording sheet according to claim 1, wherein the sheet is finely pulverized. 3. A binder comprising (1) 60 to 100% by weight of the partially saponified polyvinyl alcohol, and (2) at least one kind of polyvinyl alcohol selected from the group consisting of completely saponified polyvinyl alcohol and silane-modified polyvinyl alcohol. The ink jet recording sheet according to claim 1 or 2, which is a binder containing about 40% by weight. 4. The ink receiving layer according to claim 1, wherein the ink receiving layer further contains a crosslinking agent reactive with the hydroxyl group of polyvinyl alcohol, and the binder component in the ink receiving layer is crosslinked by the crosslinking agent. The inkjet recording sheet according to claim 1. 5. The ink-receiving layer according to claim 1, further comprising a surface treatment layer containing silica fine particles having a particle diameter of 10 to 100 nm bonded by a water-soluble polymer binder. Item 6. The ink jet recording sheet according to item 1. 6. An ink-receiving layer is formed on one side of a base sheet, and an adhesive layer is formed on the opposite side, and a release sheet is laminated on the adhesive layer as required. The inkjet recording sheet according to any one of claims 1 to 5, wherein: