JP3398478B2 - Method of manufacturing recording sheet for inkjet printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet pudding
The present invention relates to a method for manufacturing a recording sheet for printing (hereinafter referred to as a recording sheet) . 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 paper or the like has rapidly developed. The ultimate goal of these hard copies is silver halide photography. In particular, how to bring color reproducibility, image density, gloss, weather resistance, etc. close to silver halide photography has been a subject of development. Hard copy recording methods include direct shooting of displays that display images using silver halide photography, sublimation thermal transfer,
Various types of systems such as an ink jet system and an electrostatic transfer system are known. [0003] Ink jet printers are
In recent years, it has been rapidly spreading due to its ease of full color printing and low printing noise. In the ink jet method, ink droplets are ejected from a nozzle toward a recording material at a high speed, and a large amount of solvent is contained in the ink. For this reason, a recording sheet for an ink jet printer is required to absorb ink quickly and have excellent color developing properties. For example, serial Rokushi over bets the porous layer is provided alumina hydrate is known on the substrate (JP-2-
276670, JP-A-2-276671, etc.). [0004] In a recording sheet in which a porous ink absorbing layer made of alumina hydrate is provided on a base material, the porous layer of alumina hydrate has a sharpness. In some cases, scratches may occur when touching an object, and the quality of the recorded matter may be impaired. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a recording sheet which is excellent in ink absorption and coloring, and is excellent in scratch resistance. SUMMARY OF THE INVENTION [0005] The present invention is directed to a method of forming a base on a substrate.
-Pseudo- boehmite porous layer composed of mite crystals and organic binder is formed, and sol particles
This is a method for producing a recording sheet in which a silica sol as spherical primary particles of silica having a diameter of 10 to 90 nm is applied together with an organic binder and then dried to form a silica gel layer. [0006] pseudo-boehmite porous layer, boehmite crystals (compositional formula _{Al 2 O 3 · nH 2 O} , n = 1~1.5) and even rather preferable colloidal aggregates, also an organic binder ( (Hereinafter, referred to as a binder) . The pseudo-boehmite porous layer has high ink absorbency and dye fixability, and is excellent in color development of the dye because of high transparency. Therefore, it is suitable as an ink receiving layer of a recording sheet. In the recording sheet, the boehmite crystal is b
Preferably, the axes are oriented vertically. In this case, particularly high absorption and transparency are provided. [0007] The pseudo-boehmite porous layer has a pore structure substantially composed of pores having a radius of 1 to 15 nm, and when the pore volume is 0.3 to 1.0 cc / g, sufficient absorption is obtained. This is preferable because it has high transparency and high transparency. At this time, if the substrate and the dye adsorption layer are transparent, a transparent recording sheet can be obtained. The measurement of the pore radius distribution in the present invention is based on the nitrogen adsorption / desorption method. Means for providing a pseudo-boehmite porous layer on a base material include, for example, adding a binder to a boehmite sol to form a sol-like coating solution, a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, a comma coater. A method of applying and drying using a coater or the like can be adopted. As the binder, starch and its modified products, polyvinyl alcohol and its modified products, SBR latex, NBR latex, carboxymethylcellulose, hydroxymethylcellulose, polyvinylpyrrolidone and the like can be employed. The amount of the binder used is preferably about 5 to 50% by weight of the pseudo-boehmite. If the amount of the binder is less than 5% by weight, the strength of the pseudo-boehmite porous layer may be insufficient, and if it exceeds 50% by weight, the adsorptivity of the dye may be insufficient. Each is not preferred. In the present invention, the substrate is not particularly limited, and various substrates can be used. Specifically, polyester resins such as polyethylene terephthalate and polyester diacetate, polycarbonate resins, ETFE
Various types of plastic sheets or various types of paper, such as fluororesins, can be preferably used. In the case of an OHP recording sheet, the substrate must be transparent, but an opaque substrate can also be used. In this case, a recording sheet that does not impair the texture of the substrate is obtained. Further, for the purpose of improving the adhesive strength of the pseudo-boehmite porous layer, a corona discharge treatment, an undercoat, or the like can be performed. In the present invention, a silica gel layer is provided on the pseudo boehmite porous layer. The silica gel layer
It has a structure in which spherical primary silica particles are bonded to each other, and a powder composed of secondary silica particles is not substantially contained in the silica gel layer. When a powder composed of silica secondary particles is present, the transparency of the silica gel layer may be impaired, and the mechanical strength of the silica gel layer may be reduced, and the effect of protecting the pseudo-boehmite porous layer may be reduced. There is. Such a silica gel layer is obtained by adding a binder to a silica sol and applying the binder. As the silica sol, sol particles having a spherical primary particle having an average particle diameter of 10 to 90 nm are used. Moreover , the solid content concentration is 1-2.
It is preferred to use 0% by weight. As the binder, the same binder as that used for forming the pseudo-boehmite porous layer can be used, and it is particularly preferable to use a polyvinyl alcohol copolymer having a silanol group. The amount of the binder used is 1 to 1 with respect to the solid content of the silica sol (SiO ₂ equivalent)
30% by weight is preferred. 1% by weight of binder
If it is less than 10%, the mechanical strength of the silica gel layer is insufficient, and the protective effect of the pseudo-boehmite porous layer may be insufficient. If the amount of the binder is more than 30% by weight, the ink absorbency is insufficient and beading or the like may occur. Beading refers to a phenomenon in which, when recording is performed by an ink jet printer, ink droplets adhered to a recording sheet are fused on the surface of the recording sheet, thereby deteriorating the image quality. The coating liquid is applied onto the pseudo-boehmite porous layer and dried to form a silica gel layer. As a coating method, a method similar to that for the pseudo-boehmite porous layer can be suitably adopted. The thickness of this silica gel layer is 0.1
About 30 μm is preferable. The thickness of the silica gel layer is 0.
When the thickness is less than 1 μm, the protective effect of the pseudo-boehmite porous layer is not sufficiently exhibited, and the abrasion resistance may be insufficient. If the thickness of the silica gel layer exceeds 30 μm, the transparency of the coating layer may be impaired, and the ink absorbency may be impaired to cause beading, which is not preferable. A more preferred thickness of the silica gel layer is 0.1 to 10 μm. In the recording sheet produced by the present invention, the function of absorbing ink and fixing the dye is mainly provided by the pseudo-boehmite porous layer, and the silica gel layer functions as a protective layer thereof. When recording with an ink jet printer, the ink penetrates the silica gel layer and penetrates into the pseudo-boehmite porous layer, and the dye is fixed in the pseudo-boehmite porous layer. In the present invention, the mechanism by which the scratch resistance is improved by providing a silica gel layer is not clear, but when the coated surface of the recording sheet produced by the present invention is observed with a scanning electron microscope, Since the silica gel layer is formed in a state where spherical primary particles of silica gel are regularly arranged on the surface of the pseudo-boehmite porous layer, the smoothness of the coating layer surface is improved, and the slip property is provided. It seems to be. The silica gel layer also has the effect of improving the glossiness of the recording sheet, and contributes to the improvement of image quality. EXAMPLES Example 1 Using a boehmite sol synthesized by hydrolysis and peptization of aluminum isopropoxide and polyvinyl alcohol (a saponification degree of 99.8% and a polymerization degree of 4000), polyvinyl based on boehmite solids was used. A coating solution having an alcohol content of 11% by weight and a total solid content of 15% by weight was prepared. This coating liquid was applied on a 100 μm-thick polyethylene terephthalate film using a bar coater so that the coating thickness after drying was 30 μm, and dried to form a pseudo-boehmite porous layer. Next, a silica sol consisting of spherical primary particles having a diameter of 35 to 55 nm in sol particles and a polyvinyl alcohol copolymer having a silanol group (trade name: R-Polymer R-1130, manufactured by Kuraray Co., Ltd.) Solid content of 5% by weight (polyvinyl alcohol copolymer / S
A coating solution of silica sol (iO ₂ = 0.1 (weight ratio)) was prepared. This coating solution was applied on the above pseudo-boehmite porous layer, dried and further heat-treated at 140 ° C. to form a silica gel layer having a thickness of 1 μm to obtain a recording sheet. This recording sheet had sufficient ink absorbency for recording by an ink jet printer, and had good transparency. Using a friction tester (manufactured by Suga Test Instruments Co., Ltd.),
When a cotton gauze was pressed with a load of 00 g and the friction test was performed 100 times, no scratch was observed. The 60 ° specular gloss of this recording sheet was 50%. When the cross section of this recording sheet was observed with a scanning electron microscope, the silica gel layer formed on the pseudo-boehmite porous layer had a structure in which spherical primary silica particles were regularly arranged. . Comparative Example A recording sheet having only the alumina layer without the silica gel layer was obtained from the recording sheet of the example. The ink absorbency and transparency were the same as those of the recording sheet of the example. When a similar friction test was performed, scratches were observed. The 60 ° specular gloss of this recording sheet was 40%. The recording sheet produced according to the present invention has high ink absorbency and high dye adsorbing property, has high coloring properties of the dye, and has good rub resistance on the recording surface. . Also,
The glossiness is good, and a high quality image comparable to a silver halide photograph can be obtained. The recording sheet produced by the present invention can be particularly suitably used as a recording medium for an ink jet printer.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41M 5/00

Claims (1)

(57) [Claims 1] A boehmite crystal and an organic binder are provided on a substrate.
The pseudoboehmite porous layer was formed consisting of Nda, thereon, the sol particles have an average particle diameter 10~90nm silica
A method for producing a recording sheet for an ink jet printer , wherein a silica sol as spherical primary particles is applied together with an organic binder and then dried to form a silica gel layer.