JP3238522B2 - Recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheetAbout
You.

[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 absorption 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, such as JP-A-2-276670, has been proposed. Have been.

[0003]

As described above, in a recording sheet having a porous layer having good ink absorbency and good dye fixability, the plasticity of the resin during storage is low. In some cases, it was adsorbed even to a substance such as an agent, resulting in discoloration. SUMMARY OF THE INVENTION An object of the present invention is to provide a recording sheet having good ink absorbability and good dye fixability, and having no discoloration even after long-term storage.

[0004]

The present invention SUMMARY OF THE INVENTION may, on a substrate, a recording sheet having a porous ink-receiving layer containing a carboxylic acid having an aromatic nucleus (except polymer).

[0005] Carboxylic acids having an aromatic nucleus (excluding polymers)
Ku) (hereinafter, the) that arom carboxylic acids, carboxylic acid carboxylic acid group is bonded to an aromatic nucleus are preferred. As the aromatic nucleus, a benzene nucleus is preferable from the viewpoint of solubility and the like. Specifically, phthalic acid (o-dicarboxybenzene), isophthalic acid (m-dicarboxybenzene), terephthalic acid (p-dicarboxybenzene), benzoic acid,
Salicylate, full Eniru acetate can be mentioned up. Some or all of the dicarboxylic acids may be anhydrides.

[0006] The aromatic carboxylic acid may be present in the form of a salt. As the salt, a salt whose aqueous solution is acidic is preferable. Carbonitrile down dicarboxylic acid as such salts
Some of the hydrogen of the acid group is substituted salts are exemplified up with a cation. The cation at this time is preferably an alkali metal ion or an ammonium ion.

As a method for applying an aromatic carboxylic acid to the porous ink receiving layer, a solution obtained by dissolving an aromatic carboxylic acid in a suitable solvent is applied to the porous ink receiving layer formed in advance by a dipping method or a spray method. Is preferably adopted . The raw material to form a multi-porous ink-receiving layer and a method of previously mixing the aromatic nucleus carboxylic acid kills <br/> also adopted. A method of imparting a solution to the porous ink-receiving layer, as appropriate selection solvent depending on the solubility of the aromatic nuclei acids
Kill at. When the aromatic carboxylic acid is used in the form of a salt,
The use of water as a solvent has the advantage that the application of the solution is facilitated.

The content of the aromatic carboxylic acid is preferably 0.05 to 7.5% by weight based on the weight of the porous ink receiving layer. When the content of the aromatic carboxylic acid is less than 0.05% by weight, the effect of the present invention is not sufficiently exhibited, and the recording sheet may be discolored, which is not preferable. Content of aromatic carboxylic acid is 7.5
If the content is more than 10% by weight, the effect of suppressing discoloration does not increase anymore, and the absorption of the porous layer may be impaired. More preferred aromatic nucleus carbo
The acid content is 0.5-5.5% by weight.

In the present invention, the porous ink receiving layer comprises:
A porous layer capable of absorbing and fixing ink during recording.
If the thickness of the porous ink receiving layer is too small, the dye cannot be sufficiently supported, and there is a possibility that only a printed matter having a low color density may be obtained, which is not preferable.If the thickness is too large, the strength of the porous ink receiving layer decreases. Or the transparency may decrease, and the transparency or texture of the printed matter may be impaired. The preferred thickness of the porous ink receiving layer is 1
５０50 μm.

[0010] The porous ink receiving layer preferably has a structure in which inorganic particles are bound with a binder. As the material of 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 adsorbs the dye well, so that a clear recording with a high color density can be obtained using various recording methods. Here, pseudo boehmite is AlOOH
Is an alumina hydrate represented by the following composition formula, and is an aggregate having a pore structure.

When the porous layer is pseudo-boehmite,
The aromatic carboxylic acid is contained in an amount of 0.2 per mole of pseudoboehmite.
Preferably it is 30 mmol. A more preferred range is from 1 to 20 mmol.

When the pore structure of the pseudo-boehmite porous layer is substantially composed of pores having a radius of 10 to 100 ° and the pore volume is 0.3 to 1.0 cc / g, sufficient absorption is obtained. It is preferable because it has transparency and transparency. At this time,
If the substrate is transparent, a transparent recording sheet can be obtained. If the substrate is opaque, off the granted properties required without impairing the texture of the substrate. In addition to these properties, the pseudo-boehmite porous layer has an average pore radius of 30 to 7
0 ° is more preferable. The pore size distribution is measured by a nitrogen adsorption / desorption method.

In order to produce a pseudo-boehmite porous layer having the above-mentioned pore structure, it is preferable to use a boehmite sol obtained by hydrolyzing an alkoxide of aluminum. Means for coating on the substrate, the boehmite sol, preferably by adding a binder to form a slurry, roll-coated, air knife coater, blade coater, rod coater, coated on the substrate using a bar coater, etc., and dried kill in the adopted method.

Examples of the binder include starch and modified products thereof, polyvinyl alcohol and modified products thereof, SB
Organic substances such as R latex, NBR latex, hydroxycellulose and 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 other hand, if the amount is too large, the amount of ink absorbed or the amount of the dye carried may be low. About 5 to 50% by weight is preferable.

[0015] In the present invention, cut with use various ones as substrate. For example, polyesters such as polyethylene terephthalate, polycarbonate, plastic of fluororesin or the like of ETFE, etc., or Ru suitably to use <br/> paper. These substrates may be subjected to a corona discharge treatment, an undercoat or the like for the purpose of improving the adhesive strength of the porous ink receiving layer.

[0016]

Although the action of the aromatic carboxylic acid in the present invention is not clearly understood, it is adsorbed by the porous ink receiving layer and interacts with a component such as a plasticizer of a plastic which causes color development. It is thought that these adsorption or coloring are suppressed.

[0017]

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 until the liquid temperature reached 75 ° C. by a mantle heater. While stirring, 306 g of aluminum isopropoxide was added,
Hydrolysis was performed for 5 hours while maintaining the liquid temperature at 75 to 78 ° C. Thereafter, the temperature was raised to 95 ° C.
The mixture was kept at 75 to 78 ° C. for hours to peptize. The solution was further concentrated to 900 g to obtain a white sol.
The dried product of this sol was pseudo-boehmite.

1 part by weight of polyvinyl alcohol was added to 5 parts by weight of this alumina sol, and water was further added to prepare a slurry having a solid content of about 10%. This slurry was treated with corona discharge treated polyethylene terephthalate (thickness 1).
On a substrate made of 00μm), the layer thickness when dry using a bar coater the coating so that the 30 [mu] m, to form a dried擬Be <br/> Mai preparative multi porous layer.

The coated surface of the sheet obtained as described above was immersed in an ethanol solution of phthalic acid having the concentration shown in Table 1 to apply the solution uniformly. This was suspended vertically and air-dried, and then heated and baked at 140 ° C. for 4 minutes in a drum dryer.

The amount of phthalic acid in the porous material of the thus obtained recording sheet (hereinafter referred to as “treatment sheet”) was determined by cutting out a part of the treatment sheet and immersing the sheet in a hydrochloric acid aqueous solution for 12 hours. It was determined by titration with a sodium oxide solution. For comparison, a treated sheet and a recording sheet not subjected to phthalic acid treatment (hereinafter referred to as an untreated sheet)
Then, a polyvinyl chloride film of the same size was overlaid on each of the coated surfaces, kept in a room for 14 days, and the presence or absence of yellow coloring at the sheet edge was visually checked. Table 1 shows the results.

In Table 1, the unit of the phthalic acid concentration of the treatment liquid is M (mol / liter), and the unit of the amount of phthalic acid in the sheet is millimoles per mol of pseudoboehmite (AlOOH). In the column of yellowing at the end of Table 1, "Yes" means that coloring was clearly observed with the naked eye even when one sheet was observed, and "Low" means that three sheets were stacked. to the naked eye by coloration was observed, indicating that, the coloration was observed in three sheets of sheet a "no".

[0022]

[Table 1]

[0023] The coated surface of the sheet obtained in Example 1, aromatic shown in Table 2
It was immersed in an ethanol solution or an aqueous solution containing 0.2 M of the core carboxylic acid, and the solution was uniformly applied. This was suspended 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 the recording sheet, kept in a room for 14 days, and the presence or absence of yellow coloring at the end of the sheet was visually checked. Regarding any of the recording sheets, no coloring was observed even when three or more sheets were stacked.

[0025]

[Table 2]

Example 3 A coated paper obtained by applying porous silica on a paper substrate was immersed in an ethanol solution of phthalic acid having a concentration of 0.3 M in the same manner as in Example 1 from the coated surface to obtain a uniform coating. To the solution. This was suspended vertically and air-dried, and then heated and baked at 140 ° C. for 4 minutes in a drum dryer.

The treated sheet obtained in this way and the untreated sheet were compared with each other after a polyvinyl chloride film of the same size was placed on each coated surface and kept in a room for 14 days. The untreated sheet showed yellow coloring at the edges, but the treated sheet did not.

[0028]

The recording sheet of the present invention has good ink absorbency and good dye fixability. Moreover, no discoloration occurs even after long-term storage. The recording sheet of the present invention is effective for various recording methods, but is particularly suitable for a recording medium for an ink jet printer.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-51470 (JP, A) JP-A-4-92913 (JP, A) JP-A-3-96333 (JP, A) 124330 (JP, A) JP-A-5-131743 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00 B41M 5/38-5/40

Claims (2)

(57) [Claims] 1. A carboxylic acid having an aromatic nucleus on a substrate
Recording sheet having a porous ink-receiving layer containing a non- limer) . 2. The recording sheet according to claim 1, wherein the porous ink receiving layer is pseudo-boehmite.