JPH0768920A - Recording sheet and recording article - Google Patents

Abstract

PURPOSE:To obtain a recording sheet good in ink absorbability and dye fixing properties and generating no fading during long-term preservation after printing by providing a porous ink receiving layer containing a fluorescent brightener on a base material and supporting a dye on the porous ink receiving layer. CONSTITUTION:A recording sheet is constituted by providing a porous ink receiving layer containing a fluorescent brightener on a base material. The porous ink receiving layer is composed of pseudo-boehmite and the recording sheet is a recording medium for an ink jet printer. The porous ink receiving layer containing the fluorescent brightener is provided on the base material and a dye is supported on the porous ink receiving layer to constitute a recording article. By this constitution, the recording sheet good in ink absorbability and dye fixing properties and generating no discoloration even during long-term preservation is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet and recorded matter.

[0002]

2. Description of the Related Art Images are often formed using various printers such as an ink jet system, an electrostatic transfer system, and a sublimation type thermal transfer system. In this case, on plain paper,
Since sufficient absorbency and resolution cannot be obtained and a transparent material cannot be obtained, a recording sheet in which an inorganic porous layer is formed on a substrate is proposed, for example, as in JP-A-2-276670. Has been done.

[0003]

As described above, in a recording sheet having a porous layer having good ink absorbability and good dye fixing property, the plasticization of resin during storage is required. In some cases, even substances such as agents were adsorbed, causing discoloration. It is an object of the present invention to obtain a recording sheet which has good ink absorbability and good dye fixing property and which does not discolor even after long-term storage.

[0004]

The present invention provides a recording sheet having a porous ink receiving layer containing a fluorescent whitening agent on a substrate.

The fluorescent whitening agents include pyrene derivatives, coumarin derivatives, oxazole derivatives, thiazole derivatives,
Examples thereof include an imidazole derivative, an imidazolone derivative, a pyrazoline derivative, and a benzidine derivative.

The type of the fluorescent whitening agent is not particularly limited, but commercially available ones can be used.
(Bayer brand name), Hostalux (Hoechst brand name), Palani, Ultrapho (BASF brand name), Uvitex
(Ciba Geigy product name), Whitex (Sumitomo Chemical product name) and the like.

As a method for applying a fluorescent whitening agent to the porous ink receiving layer, a solution in which the fluorescent whitening agent is dissolved in a suitable solvent is applied to a preformed porous ink receiving layer by a dipping method or a spray method. The method of imparting is preferably adopted. Alternatively, a method of mixing a fluorescent whitening agent with a raw material for forming the porous ink receiving layer can also be adopted.

The content of the fluorescent whitening agent is preferably 0.01 to 10% by weight based on the weight of the porous ink receiving layer. Further, as in the case of fibers, 0.1 to 5% by weight of sodium sulfate may be added to the aqueous solution of the optical brightener. When the content of the fluorescent whitening agent is less than 0.01% by weight, the effect of the present invention is not sufficiently exhibited, and discoloration of the recording sheet may occur, which is not preferable. When the content of the fluorescent whitening agent exceeds 10% by weight, not only the coloring of the fluorescent whitening agent itself becomes a problem but also the absorptivity of the porous layer may be impaired, which is not preferable. The more preferable content of the optical brightening agent is 0.1 to 5% by weight.

In the present invention, the porous ink receiving layer is
It is a porous layer capable of absorbing and fixing ink during recording.
If the thickness of the porous ink-receiving layer is too thin, it may not be able to sufficiently support the dye, and only a printed matter having a low color density may be obtained, which is not preferable. Conversely, if it is too thick, the strength of the porous ink-receiving layer will decrease. Or the transparency may be reduced to impair the transparency or texture of the printed matter, which is not preferable. The preferable thickness of the porous ink receiving layer is 1 to 50 μm.

The porous ink receiving layer preferably has a structure in which inorganic particles are bound by a binder. As a material for the inorganic particles, silica, alumina or a hydrate thereof is preferable. In particular, the pseudo-boehmite porous layer is preferable because it has good absorbability and selectively and well adsorbs the dye, and thus various recording methods can be used to obtain a clear recorded matter with high color density. Here, pseudo-boehmite is an alumina hydrate represented by the composition formula of AlOOH, and is an aggregate having a pore structure.

When the porous layer is pseudo-boehmite,
The fluorescent whitening agent is 0.01 to 3 per mol of pseudo-boehmite.
It is preferably 0 mmol. A more preferable range is 1 to 20 mmol.

The pseudo-boehmite porous layer has a pore structure whose pores are substantially composed of pores having a radius of 10 to 100Å and has a pore volume of 0.3 to 1.0 cc / g. It is preferable because it has properties and is transparent. At this time, if the base material is transparent, a transparent recording sheet can be obtained. When the substrate is opaque, it is possible to impart the required physical properties without impairing the texture of the substrate. In addition to these physical properties, it is further preferable that the pseudo-boehmite porous layer has an average pore radius of 30 to 70Å. In addition,
The pore size distribution is measured by the nitrogen adsorption / desorption method.

In order to produce a pseudo-boehmite porous layer having a pore structure as described above, it is preferable to use a boehmite sol obtained by hydrolyzing an aluminum alkoxide. The means for applying onto the substrate is a boehmite sol, preferably with a binder added to form a slurry, which is applied onto the substrate using a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater or the like, and dried. The method can be preferably adopted.

As the binder, starch and its modified products, polyvinyl alcohol and its modified products, SBR latex, NBR latex, hydroxycellulose,
Organic substances such as polyvinylpyrrolidone can be used. If the amount of the binder used is too small, the strength of the porous ink-receiving layer may be insufficient. On the contrary, if the amount is too large, the amount of ink absorbed and the amount of dye supported may be low. It is preferably about 50% by weight.

In the present invention, various materials can be used as the base material. For example, polyester such as polyethylene terephthalate, polycarbonate, ETF
A plastic such as a fluorine-based resin such as E, or paper can be preferably used. These substrates may be subjected to corona discharge treatment or undercoating for the purpose of improving the adhesive strength of the porous ink receiving layer.

[0016]

The action of the fluorescent brightening agent in the present invention is that it absorbs ultraviolet rays and emits fluorescence from purple blue to blue green in the short wavelength region of visible region (400 to 450 nm), and is caused by components such as plasticizers of plastics. The yellow color, which is considered to be, is canceled out, and a shiny white color appears. Further, although not clear, it is also considered to have an effect of suppressing adsorption or coloring of a substance which is adsorbed by the porous ink receiving layer and causes yellowing.

[0017]

【Example】

Example 1 A glass reactor having a capacity of 2000 cc was charged with 540 g of water and 676 g of isopropyl alcohol and 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. Then, the temperature was raised to 95 ° C., 9 g of acetic acid was added, and the mixture was added for 48 hours to 7
The temperature was kept at 5 to 78 ° C for peptization. Then add 90 parts of this liquid.
Concentration to 0 g gave a white sol. The dried product of this sol was pseudo-boehmite.

To 5 parts by weight of this alumina sol, 1 part by weight of polyvinyl alcohol was added, and further water was added to prepare a slurry having a solid content of about 10%. This slurry was applied onto a base material made of polyethylene terephthalate (thickness 100 μm) that had been subjected to corona discharge treatment, using a bar coater so that the layer thickness when dried was 30 μm, and dried to form a boehmite porous material. Layers were formed.

The coated surface of the above-mentioned sheet was dipped in an aqueous solution of a fluorescent whitening agent (Whitex BF: trade name of Sumitomo Chemical Co., Ltd.) having a concentration shown in Table 1 to uniformly coat the solution. This was hung vertically and air-dried, and then heated and baked at 140 ° C. for 4 minutes in a drum dryer.

A part of the recording sheet was cut out from the thus obtained porous optical brightening agent of the recording sheet, and the solution was immersed in an aqueous hydrochloric acid solution for 12 hours, and then the solution was absorbed by an ultraviolet-visible spectrum. It was quantified by an analytical method. In addition, a polyvinyl chloride film of the same size was overlaid on the coated surface of the recording sheet and the recording sheet that was not treated with a fluorescent whitening agent for comparison, and was kept indoors for 14 days. The presence or absence of coloring was visually confirmed. The results are shown in Table 1.
Shown in.

In Table 1, the unit of the concentration of the fluorescent whitening agent in the treatment liquid is% by weight, and the unit of the fluorescent whitening agent in the sheet is the number of milligrams per gram of pseudo-boehmite (AlOOH). In the column of yellowing at the end of Table 1, "yes" means that the coloring was clearly observed with the naked eye even when one sheet was observed, and "minor" means when three sheets were stacked. No coloration was observed with the naked eye, and "no" means that no coloration was observed even after stacking three sheets.

[0022]

[Table 1]

Example 2 The coated surface of the sheet obtained in Example 1 was dipped in a 0.5 wt% aqueous solution of an optical brightener as shown in Table 2,
The solution was applied uniformly. This was hung vertically and air-dried, and then heated and baked at 140 ° C. for 4 minutes in a drum dryer.

A polyvinyl chloride film of the same size was overlaid on the coated surface of this recording sheet and kept in a room for 14 days, and the presence or absence of yellow coloring at the edge of the sheet was visually confirmed. No coloring was observed in any of the recording sheets even when three or more sheets were stacked.

[0025]

[Table 2]

Example 3 A coated paper obtained by coating porous silica on a paper substrate was processed in the same manner as in Example 1 to give a fluorescent whitening agent having a concentration of 0.5% by weight (Whitex BF: Sumitomo Chemical Co., Ltd.). Product name) An aqueous solution was dipped from the coated surface to uniformly apply the solution. This was hung vertically and air-dried, and then heated and baked at 140 ° C. for 4 minutes in a drum dryer.

On the coated surfaces of the recording sheet thus obtained and the recording sheet which was not treated for comparison,
Polyvinyl chloride films of the same size were overlaid and kept indoors for 14 days. The untreated sheet had yellow coloring at the edges, but the treated sheet did not have such coloring.

[0028]

The recording sheet of the present invention has good ink absorbability and good dye fixing property. Moreover,
No discoloration even after long-term storage. The recording sheet of the present invention is effective for various recording systems, but is particularly suitable for a recording medium for inkjet printers.

Claims (5)

[Claims] 1. A recording sheet having a porous ink receiving layer containing a fluorescent whitening agent on a substrate. 2. The recording sheet according to claim 1, wherein the porous ink receiving layer is pseudo-boehmite. 3. The recording sheet according to claim 1, which is a recording medium for an ink jet printer. 4. A recorded matter having a porous ink receiving layer containing a fluorescent whitening agent on a substrate, and a dye being carried on the porous ink receiving layer. 5. The recorded matter according to claim 4, wherein the porous ink receiving layer is pseudo-boehmite.