JPH0550739A - Recording sheet and recorded object - Google Patents

Abstract

PURPOSE:To obtain an image which is clear, high in color density, good in color reproducibility and favorably durable by using an inkjet printer. CONSTITUTION:A mixed layer of a resin which absorbs a solvent such as polyvinyl alcohol, gelatine or the like and inorganic fine particles, a pigment adsorption layer composed of porous alumina hydrate, a solvent absorbing layer of silica gel, and an opaque porous layer formed of potassium titanic acid fibers, titanium oxide, etc., are sequentially laminated on a base material in this order from the lowest.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet, particularly a recording sheet having excellent ink absorbency and color reproducibility, and a recorded matter.

[0002]

2. Description of the Related Art In recent years, with the spread of electronic still cameras or computers, hard copy technology for recording those images on a paper surface has rapidly developed. The ultimate goal of these hard copies is silver halide photography, and in particular, how to bring color reproducibility, image density, gloss, weather resistance and the like closer to silver halide photography is a development issue. As a hard copy recording method, various methods such as a sublimation type thermal transfer method, an ink jet method and an electrostatic transfer type method are known in addition to a method of directly photographing a display on which an image is displayed by a silver halide photograph.

Inkjet printers are
It has become popular rapidly in recent years because it is easy to make full color and has low printing noise. The ink jet system ejects ink droplets from a nozzle toward a recording material at high speed, and contains a large amount of solvent in the ink. Therefore, a recording sheet for an inkjet printer is required to quickly absorb the ink and have excellent color forming property. For example, a recording sheet is known in which a porous layer of alumina hydrate is provided on a base material (Japanese Patent Laid-Open No. HEI 2).
-276670, JP-A-2-276671, etc.).

[Problems to be Solved by the Invention]

The present invention provides a recording sheet suitable for an ink jet printer, which is capable of quickly absorbing ink, having high color reproducibility, high color density and high durability. The purpose is to provide.

[0005]

According to the present invention, a substrate is provided with a layer containing a resin that absorbs a solvent in an ink and inorganic fine particles, and a dye adsorbing a porous alumina hydrate is provided on the layer. A recording sheet having layers is provided.

In the present invention, since a layer containing a resin that absorbs the solvent in the ink and inorganic fine particles is provided below the alumina hydrate layer, the alumina hydrate when recorded with an ink jet printer or the like. The solvent in the layer can be absorbed in the layer below. Therefore, the solvent remaining in the alumina hydrate layer can be minimized. For this reason, the dye does not move due to the diffusion of the solvent remaining in the alumina hydrate layer, and the dye is stably fixed over time, and a clear image without bleeding can be obtained.

In the layer containing the resin that absorbs the solvent in the ink and the inorganic fine particles, the inorganic fine particles form a discontinuous portion in the resin layer and have the action of improving the absorption rate of the solvent into the resin. Conceivable. If the inorganic fine particles are porous and absorbable themselves,
Although it is preferable because it improves absorbency, it does not necessarily have absorbency itself.

The inorganic fine particles preferably have a particle diameter of 1 μm or less. When the particle diameter exceeds 1 μm, it becomes difficult to uniformly coat the base material with the OH.
In the case of a recording sheet that requires transparency such as the P sheet, the transparency of the sheet may be impaired, which is not preferable. A particle diameter of 10 to 500 nm is more preferable. When it is sufficiently smaller than the wavelength of visible light, the transparency is particularly improved.

The material of the inorganic fine particles is not particularly limited, but inorganic oxide fine particles such as alumina or silica are preferable because it is easy to obtain fine particles having a controlled particle size. Specifically, it is preferable to use sol-shaped fine particles such as alumina sol and silica sol.

The content of the inorganic fine particles in the layer containing the solvent-absorbent resin and the inorganic fine particles is preferably 5 to 50% by weight. If the content is less than 5% by weight,
The effects of the present invention may not be sufficiently exhibited, and the resolution of the recording sheet may not be improved. On the contrary, if the content exceeds 50% by weight, the effect of preventing bleeding may be impaired.

The layer of the resin that absorbs the solvent in the ink is preferably one that absorbs the solvent by swelling, and the degree of weight swelling with respect to the solvent (the resin layer before and after immersing the resin in the solvent at 30 ° C. for 48 hours). Ratio of water absorption to the weight of
Is 1.0 or more and 10 or less, preferably 1.5 or more and 5 or less. Excessive swelling can have an adverse effect on the application of alumina hydrate.
When the transparency of this layer is high, a clear recorded matter can be obtained, which is preferable.

As such a resin, when the ink solvent is an aqueous solvent, polyvinyl alcohol and its modified products, starch and its modified products, gelatin, polyvinylpyrrolidone, sodium polyacrylate and the like can be preferably used.

The thickness of the layer containing the solvent-absorbing resin and the inorganic fine particles is preferably about 0.5 to 50 μm. When the thickness is less than 0.5 μm, the effect of the present invention is not sufficiently exhibited, and therefore it is not suitable. Thickness is 50 μm
If it exceeds, the layer becomes opaque and a clear image cannot be obtained, which is not preferable.

The means for providing the layer containing the solvent-absorbing resin and the inorganic fine particles on the substrate is, for example, mixing the resin and the inorganic fine particles and dissolving them in a suitable solvent, and then a bar coater, reverse coater or comma coater. It is possible to employ a method in which the solvent is removed by coating using a gravure coater, a die coater or the like. Alternatively, the layer may be formed by directly synthesizing the resin on the substrate by a chemical reaction.

As the alumina hydrate, pseudo-boehmite (AlOOH) is preferable because it absorbs and fixes the dye well. The alumina hydrate layer has a pore structure of pores having a radius of substantially 10 to 100Å and a pore volume of 0.3.
When it is ~ 1.0 cc / g, it has sufficient absorbability,
In addition, the alumina hydrate layer is also transparent, which is preferable.
At this time, if the base material is transparent, a transparent recording material can be obtained. Even when the substrate is opaque, it is possible to obtain a high-quality image that does not impair the texture of the substrate.

Desirably, in addition to these physical properties, the average pore radius of the alumina hydrate layer is 20 to 60Å, and the volume of pores having a radius of ± 10Å of the average pore radius is the total pore volume. Of 45% or more is particularly preferable from the viewpoint of achieving both dye fixing property and transparency. Average pore radius is 3
It is more preferable that the volume of pores having a radius of 0 to 50Å and an average pore radius of ± 10Å is 55% or more of the total pore volume. The pore radius distribution in the present invention is measured by the nitrogen adsorption / desorption method.

The alumina hydrate layer can be used not only as a single layer but also as a combination of layers having different pore radius distributions. The pore radius distribution can be appropriately optimized depending on the type of dye. The pore radius may be appropriately selected from the range of about 10 to 100Å depending on the dye. In the case of an ordinary inkjet printer, an alumina hydrate having an average pore radius of 20 to 30 Å is provided in the lower layer to adsorb a magenta dye that easily enters relatively small pores, and to have an average fineness on it. It is preferable to provide an alumina hydrate layer having a pore radius of 35 to 50 Å to fix a cyan dye that is difficult to enter into small pores. It is also possible to provide an alumina hydrate layer having an average pore radius having an intermediate value between the above two layers in the middle of the above two layers.

The thickness of the alumina hydrate layer is appropriately selected according to the specifications of each printer, etc., but each layer has a thickness of 0.5-2.
It is preferable to adopt 0 μm, and 5 to 50 μm in total when laminated. If the thickness of the alumina hydrate layer is less than 0.5 μm, the dye may not be sufficiently adsorbed.
If it exceeds 0 μm, the transparency of the alumina hydrate layer may be impaired or the strength of the layer may be reduced, and thus it is not preferable.

In the present invention, the base material is not particularly limited, and various materials can be used. Specifically, various plastics or papers such as polyester resins such as polyethylene terephthalate and polyester diacetate, polycarbonate resins, fluorine resins such as ETFE can be preferably used. Also,
For the purpose of improving the adhesive strength of the alumina hydrate layer, corona discharge treatment or undercoating can be performed.

Means for providing the alumina hydrate layer on the substrate is, for example, a binder added to alumina hydrate to form a slurry, and a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, a comma coater, etc. It is possible to employ a method of applying and drying.

In the present invention, for the purpose of absorbing the solvent in the ink, a porous layer (hereinafter referred to as solvent absorption) which is solvent absorbing and has a lower dye fixing property than alumina hydrate is formed on the upper layer of the alumina hydrate layer. A porous porous layer). The material of this layer is preferably porous silica.
In this case, if the pore structure of the alumina hydrate layer is appropriate, the dye does not remain in the porous silica layer but is selectively adsorbed in the alumina hydrate layer. At this time, when a transparent substrate is used and the printed matter is viewed from the transparent substrate side (the back side of the printed side), the transparency of the transparent substrate is maintained almost as it is, and a clear image can be seen.

As the porous silica, it is suitable to use fine powder silica gel having an average particle diameter of 1 to 50 μm and a pore volume of about 0.5 to 3.0 cc / g. If the average particle diameter is less than the above range, the absorbency of the solvent in the ink becomes insufficient, and if they exceed the above range, the surface of the solvent absorbing layer becomes inhomogeneous and the image becomes uniform. It is not preferable because it may disappear. When the pore volume is less than the above range, the absorbency of the solvent in the ink becomes insufficient, and when they exceed the above range, the absorbency becomes too high, and even the dye is absorbed and supported. Both of them are not preferable because they may occur.

Although the thickness of the solvent-absorbing porous layer is strictly determined by the type of ink used, the type of solvent used, the amount of ink, etc., it is generally suitable to use about 5 to 50 μm. When the thickness is less than the above range, the image is bleeding due to lack of absorption, and when the thickness is more than the above range, the absorption may be too high and the dye may not be absorbed to form an image. Therefore, both are not preferable.

As the means for providing the solvent-absorbing porous layer on the porous alumina hydrate layer, the same method as the above-mentioned means for forming the porous alumina hydrate layer can be preferably adopted.

In the present invention, when a transparent sheet is used as the base material, after fixing the dye with an ink jet printer or the like, the image of the alumina hydrate layer is printed with the ink through the transparent base material. It can be observed from the opposite direction. This image has good gloss if the substrate has a glossy surface. Further, since it is protected by the base material, a durable image can be obtained. At this time, when a highly opaque porous layer such as titanium oxide powder or potassium titanate whiskers is provided on the upper layer of the alumina hydrate layer and the ink is driven through this layer, titanium oxide powder or the like is used. This is preferable because a recorded image with a beautiful image can be obtained in the background of the layer. Further, the solvent-absorbing porous layer as described above can be provided between the alumina hydrate layer and the opaque porous layer.

In this case, the opacity of the recording sheet is 70%.
The above is preferable. If the opacity is less than 70%, a clear image cannot be obtained without backing when viewing an image with reflected light, and the light source itself may be seen through when viewing with transmitted light. Not preferable. Although the optimum value of the opacity varies depending on the application, it is possible to eliminate the direct influence from the back by having the opacity of 70% or more. It is more preferable that the opacity is 85% or more. When observing an image with reflected light, it does not matter if light is not transmitted at all, but when a light source is arranged behind and an image is observed with transmitted light, the opacity is 95% or less. It is preferable.

Here, the above opacity is based on JIS P813.
Defined in 8. That is, by placing a white and black standard plate on the back side of the recording sheet, a reflection color densitometer (Konica PDA-
45) is used to measure the reflection color density. Then, the reflectance is obtained from the relationship of D = log (1 / R) (D: reflection color density, R: reflectance). This is JIS P8
Apply to 138 to determine opacity in%.

The opaque porous layer is preferably white in general, but may be a layer colored in a specific color depending on the application. When a white layer is used, it is also effective to add a fluorescent whitening agent or the like.

The material of the opaque porous layer is not particularly limited, but includes organic or inorganic particles such as benzoguanamine resin, urea formalin resin, potassium titanate fiber, titanium oxide, calcium carbonate, zinc oxide and lead oxide. Is preferably used. When the surface charge is neutral or negative, the dye in the ink is hard to be adsorbed, which is particularly desirable. Further, the particles themselves do not necessarily have to be porous, and a gap may be formed between the particles when forming a layer.

When titanium oxide is used as the opaque porous layer, it is particularly preferable because it has good permeability of the dye of the ink and high opacity. As the titanium oxide, both rutile type and anatase type can be used. In addition, by mixing porous silica in addition to titanium oxide, it can be preferably used particularly in the case of a machine using a large amount of ink.

The coating amount of these opaque porous layers is appropriately selected according to the standard of the printing apparatus (particularly, the amount of ink per unit area), but in general, the range of 1-100 μm is suitable. As the coating method, the same method as for the alumina hydrate layer is possible.

[0032]

【Example】

(Example 1) A glass reactor having a capacity of 2000 cc (with a separable flask, stirring blades and a thermometer) was charged with water 810.
g and 676 g of isopropanol were charged, and the liquid temperature was heated to 75 ° C. by a mantle heater. While stirring, 306 g of aluminum isopropoxide was added, and the liquid temperature was adjusted to 7
Hydrolysis was carried out for 5 hours while maintaining at 5 to 78 ° C. After that, the temperature was raised to 95 ° C., 9 g of acetic acid was added, and 48 hours
The temperature was kept at 75 to 78 ° C for peptization. Furthermore, this liquid
It concentrated until it became 00g and obtained white sol. The dried product of this sol was pseudo-boehmite, the average pore radius measured by the nitrogen adsorption / desorption method was 30Å, and the pore volume having a pore radius of 10 to 100Å was 0.6 cc / g.

On the other hand, water was added to 85 parts by weight of polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd.) and 15 parts by weight of silica sol (average particle diameter of 15 nm by laser method) to give a coating solution having a total solid content concentration of 5% by weight. Prepared. This coating liquid was applied to a substrate made of a polyethylene terephthalate film (thickness 100 μm) that had been subjected to corona discharge treatment,
A bar coater was used to apply and dry the film so that the film thickness after drying was 10 μm. Next, a coating solution (solid content ratio 100: 15) obtained by adding polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) to the above alumina sol was applied by a bar coater so that the coating amount when dried was 10 μm, and dried. Then
A recording sheet was obtained.

(Example 2) On the upper layer of the sheet of Example 1,
Using a bar coater, a mixed slurry of porous silica gel (Carplex # 80, manufactured by Shionogi Pharmaceutical Co., Ltd.) and PVA (solid content ratio 3: 1, total solid content 15% by weight) has a film thickness of 20 μm when dried. And then dried. On this upper layer, potassium titanate whiskers (K ₂ O · 6TiO 3
₂ , an average fiber length of 50 μm, an average fiber diameter of 0.2 μm, an aspect ratio of 200 to 300) and a mixed slurry of PVA (solid content ratio 5: 1, total solid content 30% by weight) were dried using a bar coater. Coating to a film thickness of 30 μm
A recording sheet was obtained by drying.

(Examples 3 and 4) In Examples 1 and 2,
The silica sol was obtained by hydrolysis of alkoxide, and the average particle diameter by the laser method was 230 nm.
A recording sheet was obtained in the same manner except that the boehmite-based alumina sol was used.

(Comparative Examples 1 and 2) In Examples 1 and 2,
A recording sheet was obtained in the same manner except that only PVA was applied instead of applying the mixture of PVA and silica sol on the substrate.

Regarding the recording sheets of Examples 1 and 3 and Comparative Example 1, an ink jet printer (manufactured by IRIS,
The ink jet printer (manufactured by Canon Inc., Bubble Jet Copier PIXEL) is used for recording sheets of Smart Jet 4012), Examples 2 and 4 and Comparative Example 2.
The evaluation pattern was printed by PRO), and the color density, resolution, and bleeding amount were measured.

The color density was measured by printing a black band and using a reflection color densitometer (PDA-45 manufactured by Konica). Regarding the resolution, a stripe having a resolution of 200 dots / inch was printed, and the sharpness was evaluated on a scale of 10. For bleeding, print a blue band that is a mixture of cyan and magenta, and
It was left to stand in a 0% constant temperature and humidity chamber for 24 hours. The bleeding out of the magenta ink blue band was photographed with an optical microscope, and the width thereof was measured. The results are shown in Table 1.

[0039]

[Table 1]

[0040]

The recording sheet of the present invention has good color reproducibility and high durability. Even when printed with an inkjet printer, the solvent remaining in the alumina hydrate is minimized, so that even dyes that are difficult to fix on the alumina hydrate are suppressed from moving over time, and bleeding is greatly reduced.

Claims (5)

[Claims] 1. A recording sheet having a layer containing a solvent-absorbent resin and inorganic fine particles on a substrate, and a dye adsorbing layer made of porous alumina hydrate on the layer. 2. The recording sheet according to claim 1, further comprising a porous layer which is solvent-absorptive and has a lower dye fixing property than alumina hydrate, as an upper layer of the dye adsorption layer. 3. The recording sheet according to claim 1, further comprising an opaque porous layer on the dye adsorbing layer. 4. A recorded matter having a layer containing a solvent-absorbent resin and inorganic fine particles on a base material, and a porous alumina hydrate layer having a dye fixed thereon as an upper layer. 5. A transparent substrate, a layer containing a solvent-absorbing resin and inorganic fine particles, a dye-fixed porous alumina hydrate layer, a solvent-absorbing and alumina hydrate dye in order from the viewing side. A recorded material in which a porous layer having low fixability and an opaque porous layer are laminated.