JP2818353B2 - Record 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 sheet for use in an ink jet recording system, and more particularly to a recording sheet having a high density of images and characters recorded on the sheet, a clear color tone, and excellent ink absorption. The present invention relates to a recording sheet for an ink jet recording system suitable for high density full color recording.

[0002]

2. Description of the Related Art In an ink jet recording system, fine droplets of ink are caused to fly according to various operating principles, and a part or all of them are adhered to a recording sheet such as paper to record an image or a character. However, due to the low noise, easy colorization, high-speed recording, and the need for development and fixing like silver halide photography, facsimile, various printers, etc. Is being applied.

As inks for ink jet recording,
Ink that is difficult to dry is used to prevent clogging of the jet nozzle. The components of this ink are binder, dye,
Generally, a solvent, an additive and the like are dissolved in water.

[0004] Therefore, when printing and recording is performed by an ink jet printer, the recording sheet needs to have water absorbency, and paper specially designed to have a function of sufficiently absorbing ink has been usually used.

In recent years, with the increase in density and full color of ink jet recording, recording is performed on, for example, a transparent plastic base film, and a slide or an overhead projector (OHP) sheet or a positive plate for color printing is prepared. Use as a color separation when doing
Further, there is an increasing demand for recording on a transparent or opaque plastic substrate film and using it as a display sheet in a show window or the like.

In these applications, in order to obtain high-resolution, multi-color, high-quality ink jet recording, recording sheets are required to have higher and wider characteristics.

[0007] 1) The absorption speed of the ink on the recording sheet is high. 2) The coloring properties of the coloring components of the ink are excellent, and the optical density (O
D) is high. 3) No beading (a phenomenon in which a large amount of ink is unevenly distributed on the surface of the receiving layer to cause so-called “density unevenness”) does not occur. 4) Bleeding (phenomena where borders of different colors blur)
Does not occur. 5) Excellent blocking resistance. 6) Whiteness is high when the material is excellent in translucency or is opaque. 7) The surface is glossy. It is necessary to satisfy basic requirements such as

The above-mentioned beading phenomenon is particularly remarkably observed when large ink droplets are used, when the ejection frequency of the droplets is high, or when multicolored droplets are used as in color recording. This phenomenon makes it difficult to obtain a high-definition image.

[0009] The bleeding resistance is the same as in the case of forming a full-color image using multicolor inks.
At the same time, a large amount of ink is required when landing on a recording sheet. That is, when different colors are deposited, it is necessary to absorb the ink as quickly as possible so that the boundary between the different colors does not greatly blur.

Further, the above-mentioned blocking resistance is also required when a large amount of ink is simultaneously deposited on a recording sheet as in the case of forming a full-color image. That is, the resin of the ink receiving layer that has absorbed a large amount of ink dissolves and swells due to the ink, develops tackiness, and causes a phenomenon of sticking to paper, plastic film, and the like. This phenomenon is called a blocking phenomenon, and it is necessary that the blocking phenomenon does not occur even if a large amount of ink is applied to the recording sheet.

Various studies have hitherto been made to satisfy the above-mentioned functions, and although some results have been obtained, recording sheets satisfying all of these required characteristics have not yet been known.

[0012] For example, the ink receiving layer of an ink jet recording sheet has heretofore often been substantially composed of at least one of a hydrophilic natural resin and a water-soluble or hydrophilic synthetic resin. When droplets are deposited, a beading phenomenon occurs, making it difficult to obtain a high-definition image. In addition to the beading, in the case of full color, a bleeding phenomenon occurs, and there is a problem that high-resolution image quality is impaired. Furthermore, the blocking resistance is insufficient,
When a water-insoluble or hydrophobic compound is used in combination, the blocking resistance is improved, but on the other hand, there is a disadvantage in that the ink absorption is deteriorated.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink absorbing, blocking, beading and bleeding resistance (even when a large amount of ink is applied at a high density such as full color printing). It is an object of the present invention to provide a recording sheet for an ink jet recording system which is excellent in the density of recorded images and characters, has a clear color tone, and is excellent in resolution.

[0014]

According to the present invention, there is provided a recording sheet having at least one ink-receiving layer provided on a plastic base film,
This is achieved by a recording sheet for an ink jet recording system, wherein the ink receiving layer is made of cationic colloidal silica, alumina hydrate and a hydrophilic resin.

In the present invention, as the plastic substrate film, either a translucent or non-translucent substrate film can be used. Examples of the translucent base film include films (sheets) made of plastic such as polyester, diacetate, triacetate, acrylic polymer, cellophane, celluloid, polycarbonate, polyvinyl chloride, and polyimide. Among these, a polyester film is preferred.

To further explain the polyester film, the polyester is a crystalline linear saturated polyester produced from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Preferable examples include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, and poly (1,4-cyclohexylene dimethylene terephthalate). Further, a copolymer in which a part of these is substituted with another component, or a mixture with polyalkylene glycol or another resin may be used.

The polyester film can be produced by a conventionally known method. For example, the polyester is dried and then melted, extruded from a die (for example, a T-die, an I-die, etc.) onto a cooling drum and rapidly cooled to form an unstretched film. The unstretched film is stretched biaxially, and further heat-fixed. Can be manufactured.

The thickness of the plastic base film is preferably 25 to 300 μm, more preferably 50 to 200 μm.
m is preferred. If the film thickness is less than 25 μm, the transportability in the machine at the time of recording deteriorates, while if it exceeds 300 μm, it is disadvantageous in terms of cost.

In the present invention, the ink receiving layer provided on the plastic substrate film is composed of cationic colloidal silica, hydrated alumina and a hydrophilic resin.

Colloidal silica is usually an anionic colloidal dispersion in which ultrafine particles of silicic anhydride (silica) are stably dispersed in water, and is manufactured by Du Pont's Lual.
ox, Nissan Chemical's Snowtex and other brand names.

Various production methods are known for these colloidal silicas. In general, an aqueous solution of sodium silicate is passed through a cation exchange resin by a method using an ion exchange resin to convert SiO ₂ / Na ₂ O. 60-130 sol,
This is aged by heating to 60 ° C. or more to grow into independent dispersed particles, and by adding a new sol through the ion-exchange resin layer, polymerized and precipitated to grow to an average particle diameter of 3 to 200 nm and stable. It is manufactured by a method of preparing a sol. And silica sol has a siloxane structure,
Normally, the silica particles have a negative charge (anionic) sufficient to repel each other.

The cationic colloidal silica in the present invention is a compound in which at least the surface of the silica particles is cationically charged by containing a compound of a polyvalent metal ion such as an aluminum ion or an organic cationic compound on or on the silica surface. Things. Particularly preferably,
Colloidal silica totally cationized by basic aluminum. These colloidal silicas, for example, Snowtex AK of Nissan Chemical Co., Ltd., are commercially available and available.

The particle size of the cationized colloidal silica is preferably in the range of 3 to 200 nm.
3 to 50 nm, particularly 3 to 20 nm, in the case of having translucency.
The range of nm is preferred.

Various alumina hydrates can be used in the present invention, and pseudo-boehmite is particularly preferred. According to this pseudo-boehmite, excellent coloring properties can be obtained. Here, the pseudo-boehmite is an aggregate of colloidal boehmite (AlO (OH)) particles, for example, “Cataloid AS” from Catalyst Chemical Industry Co., Ltd., “Alumina Sol # 520” from Nissan Chemical Industry Co., Ltd. It is supplied to the market under brand names such as "Clearsol" of Kawaken Fine Chemicals Co., Ltd.

Such pseudo-boehmite is produced by various methods, and a method of producing by pseudohydrolysis of aluminum alkoxide is particularly preferable. Pseudo-boehmite produced by the hydrolysis of aluminum alkoxide has a uniform particle diameter and a controlled pore structure, and is therefore particularly preferable as a dye adsorbent for a recording sheet.

The hydrophilic resin in the present invention is not particularly restricted but includes, for example, hydrophilic natural resins such as albumin, gelatin, casein, starch, cationic starch, acacia, sodium alginate, polyvinyl alcohol, cationized polyvinyl alcohol, polyamide, Polyacrylamide, polyvinylpyrrolidone, quaternized polyvinylpyrrolidone, poly (N-vinyl-3-methylpyrrolidone), polyvinylimidazole, polyallylamine, polyallylamine hydrochloride, polyethyleneimine, polyvinylpyridium halide, melamine resin, polyurethane,
Examples include water-soluble or hydrophilic synthetic resins such as carboxymethylcellulose, hydroxyethylcellulose, cationized hydroxyethylcellulose, hydroxypropylcellulose, polyester, sodium polyacrylate, and polyalkylene oxide. Among these, starch and its modified products, polyvinyl alcohol and its modified products, SBR latex, NBR latex, hydroxyethyl cellulose, gelatin, polyvinyl pyrrolidone and its copolymers, polyacrylic acid, sodium polyacrylate and the like are preferable, and particularly polyvinyl. Alcohol and its modified products are preferred.

In the present invention, the weight ratio of the cationic colloidal silica to the alumina hydrate is from 98: 2 to 30:70, preferably from 95: 5 to 55:45. If the proportion of the cationic colloidal silica is too large, the film-forming properties deteriorate, cracks occur during printing, and good images cannot be obtained. On the other hand, if the proportion of the alumina hydrate is too large, bleeding (bleeding) becomes large, and a high-resolution image cannot be obtained.

The weight ratio of the total amount of the cationic colloidal silica and alumina hydrate to the hydrophilic resin is 98: 2.
５０50: 50. If the proportion of the hydrophilic resin is too small, the film-forming properties deteriorate, and good images cannot be obtained. On the other hand, if the proportion of the hydrophilic resin is too large, the ink absorption rate decreases, and beading tends to occur.

In the present invention, the thickness of the ink receiving layer is from 1 to
100 μm is preferable, and particularly preferably 3 to 50 μm.
If the thickness is less than 1 μm, the ink absorbency and dye absorption are insufficient, while if it exceeds 100 μm, the transparency may be impaired or the strength of the receptor layer may be undesirably reduced.

In forming the ink receiving layer on the plastic substrate film, the coating liquid may be directly applied as it is. However, when the adhesion between the substrate film and the formed ink receiving layer is insufficient. Before forming the receiving layer,
It is preferable to apply an easy contact plier on the base film. As a method of forming the ink receiving layer on the base film, a usual coating means such as a gravure coat, a bar coat, a reverse roll coat, and a knife coat can be used.

In the present invention, the ink receiving layer may be formed only on one side or both sides of the plastic base film.

[0032]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” and “%” are based on weight unless otherwise specified.

The properties of the recording sheet were measured by the following methods.

(1) Ink fixability After recording full dots of three colors, yellow, cyan, and aagenta, the time (second) until the recording image is touched with a finger when left at room temperature and no longer adheres to the finger is recorded. Measure.

(2) Image Density After recording full dots of three colors of yellow, cyan and magenta on a recording sheet, the optical density (OD) of the printed matter is measured using a Macbeth densitometer TR-524.

(3) Beading After full dots of three colors, yellow, cyan and magenta, are recorded on a recording sheet, they are visually judged. The middle is defined as △.

(4) Bleeding resistance After recording two full-color dots of red, blue and green on a recording sheet, judgment was made by visual observation. And △.

(5) Blocking resistance After recording full dots of three colors of yellow, cyan and magenta on a recording sheet, the recording sheet is left at room temperature for 3 minutes, and the same recording sheet is laminated on the recorded image under a pressure of 40 g / cm ^2. Judgment is made based on whether the film can be easily peeled off. Those that easily peel off are marked with ○, those that require considerable force for peeling are marked with x, and those between them are marked with △.

[0039]

Examples 1 to 3 and Comparative Examples 1 to 4 Cationic colloidal silica having an average particle diameter of 8 nm and an alumina sol having a pseudo-boehmite structure coated with alumina (Al ₂ O ₃ ) (catalyst chemical: cataloid) AS-3) and polyvinyl alcohol (Kuraray: PVA117) were added with water to prepare a coating liquid having a composition shown in Table 1 and having a solid content of 10%.

The amount of the coating solution after drying was 10 g /
The thickness is 100 μm by a bar coater method so as to obtain m ^2.
m polyethylene terephthalate film,
It was dried at 140 ° C. for 3 minutes.

On the obtained recording sheet, ink jet recording was performed using a Canon Bubble Jet Printer BJC-820J to print full dots of three colors of yellow, cyan and magenta or full dots of two colors of red, blue and green. Then, each characteristic was evaluated. Table 1 shows the results.
Shown in

[0042]

[Table 1]

According to the present invention, since the ink receiving layer is composed of cationized colloidal silica, alumina hydrate and a hydrophilic resin, the ink is quickly absorbed into the inside thereof,
Even if different colors of ink adhere to the same spots in a short time, there is no beading or bleeding phenomenon, giving a clear image with high resolution, and the obtained image has high density and blocking resistance. It is possible to provide a recording sheet for an ink jet recording system, which is also excellent.

Claims (3)

(57) [Claims] 1. A recording sheet having at least one ink receiving layer provided on a plastic base film, wherein the ink receiving layer is composed of cationic colloidal silica, alumina hydrate and a hydrophilic resin. A recording sheet for an ink jet recording method, characterized by the following. 2. The weight ratio of the cationic colloidal silica to the alumina hydrate is 98: 2 to 30:70, and the weight ratio of the total amount thereof to the hydrophilic resin is 98: 2 to 50:50. The recording sheet according to 1. 3. The recording sheet according to claim 1, wherein the plastic base film is a polyester film.