JP2002264466A - Method for manufacturing ink jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording medium having gloss and excellent ink absorbability and a method for manufacturing the same. SOLUTION: The ink jet recording medium comprises at least one or more ink acceptive layers provided on a support. The ink acceptive layer of the uppermost layer contains a polyvinyl alcohol and a boric acid and/or a borate. The ink acceptive layer of the uppermost layer is provided by a casting method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a recording medium having good ink absorptivity and glossiness, and more particularly to a method for forming a recording medium using aqueous ink, comprising polyvinyl alcohol on the outermost layer. The present invention relates to a method for manufacturing an ink jet recording medium having an ink receiving layer used as an adhesive.

[0002]

2. Description of the Related Art When a recording medium having a glossy surface is used for printing, an extremely excellent printing effect can be obtained and a high-grade feeling can be given to a packaging material.
Used in many fields. As a method for imparting such a glossiness to the surface of a recording medium, a cast coating method is known.

[0003] The cast coating method is a method in which a coating liquid composition containing a pigment or an adhesive as a main component is applied to base paper and then subjected to a cast finish. Specifically, the coating layer is wetted. Wet-casting method (direct method) in which the coating layer is pressed to the surface of a mirror-finished heating drum during a certain period and dried, and the wet coating layer is dried or anti-dried once to solidify and then wet plasticized with a rewet liquid Re-wet cast method, which is pressed and dried on a mirror-finished heating drum,
There are generally known three types of methods, a gel casting method (coagulation method) in which a wet coating layer is made into a gel state by coagulation treatment, and is pressed against a mirror-finished heating drum and dried.

[0004] Each of these cast coat methods,
The coating layer in the wet plasticized state is pressed against a mirror-finished heating drum and dried, and is released from the heating drum to copy the mirror surface, but is common among those skilled in the art as a separate technology. Is what it is. In addition, the surface of the recording medium obtained by the casting method has a higher gloss than a recording medium whose surface is finished by a super calender or the like,
High smoothness. In the case of the gel casting method (coagulation method), casein is mainly used as an aqueous binder, which is salted out with a salt solution (coagulant) such as calcium formate to form a coating layer. Often gelled.

On the other hand, in recording fields such as printing and ink jet, inks and recording media have been improved, and various compounds have been used as materials. For example, JP-A-60-232990 discloses an ink jet recording sheet using a cationic hydrated aluminum oxide. However, in this case, when casein is mixed with cationic alumina powder or alumina sol, the gel casting method using the above-mentioned salt solution of casein and calcium formate cannot be used. In addition, when a conventionally known coating solution containing polyvinyl alcohol is applied and then a boric acid or borate coagulant is used, the surface portion of the coating layer is particularly hardened, and even to the inside. Since it was not possible to cure the ink uniformly, there was a disadvantage that the ink absorbability was reduced.

[0006]

Accordingly, the present inventors have conducted intensive studies on a method of uniformly curing the interior of a polyvinyl alcohol layer using a system of polyvinyl alcohol and boric acid or borate. The present inventors have found a new technique of applying an acidic coating solution containing boric acid or borate and then making the coating solution alkaline, and have reached the present invention. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing an inkjet recording medium having gloss and excellent ink absorbability.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
At least one surface of the support has a pH of 4.0 containing polyvinyl alcohol and boric acid and / or borate.
After applying the following acidic coating liquid to form a coating layer, the coating layer is coagulated using an alkaline coagulating liquid, and the coating layer is heated while the coating layer is in a wet state. The present invention has been attained by a method for producing an ink jet recording medium, characterized in that it is pressed against a finished mirror-finished metal surface to impart gloss to the surface of a coating layer. It is preferable that the ink receiving layer further contains a cationic pigment. Further, the ink receiving layer may have a multilayer structure, and in this case, the layer containing the polyvinyl alcohol and boric acid and / or borate is provided as the outermost layer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The support used in the present invention is not particularly limited as long as it has air permeability, and may be transparent or opaque. In the present invention, for example, high-quality paper, photographic paper base paper, drawing paper, painting paper, art paper, coated paper, cast coated paper, paper such as kraft paper, and nonwoven fabric can be appropriately used according to the application. . From the viewpoint of operability, a preferable air permeability is 1,000 seconds or less,
From the viewpoint of coatability, it is desirable that the degree of Stekigt size be 5 seconds or longer.

The ink receiving layer of the ink jet recording medium may contain a pigment, and preferably contains 70 to 95% by weight of the pigment from the viewpoint of ink absorption. Pigments used in the ink receiving layer in the present invention include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, titanium dioxide, zinc oxide, zinc carbonate, satin white, magnesium carbonate, magnesium silicate, calcium sulfate, calcium silicate , Aluminum silicate, aluminum hydroxide, alumina sol, colloidal alumina, alumina and alumina hydrate such as pseudoboehmite, zeolite,
Examples thereof include silica and plastic pigment. In the present invention, it is preferable to use alumina or synthetic silica from the viewpoint of ink absorption or ink fixability.

The boric acid (H ₃ BO) used in the present invention
₃ ) may be reagent grade or industrial grade. Examples of the borate include borax (sodium borate), zinc borate, and ammonium borate. In the present invention, these may be used alone or as a mixture. The polyvinyl alcohol used in the present invention is not particularly limited in terms of the degree of saponification and ionicity, and can be appropriately selected from known ones. The ink receiving layer containing polyvinyl alcohol and boric acid and / or borate in the present invention may be provided on a binder layer or another known ink receiving layer which may be provided on a support. That is, when the ink receiving layer is composed of two or more layers, it is provided as the outermost layer.

[0011] In the ink receiving layer as the outermost layer, oxidized starch, as a binder other than the polyvinyl alcohol,
Starches such as esterified starch, enzyme-modified starch, and cationized starch; proteins such as casein and soy protein; cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose; acrylic emulsion, vinyl acetate emulsion, acryl-vinyl acetate emulsion, vinylidene chloride Emulsions, water-dispersible polymer compounds such as styrene butadiene latex, acrylonitrile butadiene latex, and polyester dispersion can be used together as long as the effects of the present invention are not impaired. The proportion of polyvinyl alcohol in the binder is preferably at least 50%, more preferably at least 80%. If the ratio of polyvinyl alcohol in the binder is low, coagulation by boric acid or borate becomes insufficient, and a glossy surface tends to be unable to be obtained.

In the present invention, a coating solution containing polyvinyl alcohol and boric acid and / or borate is adjusted to be acidic, the coating solution is applied to form a coating layer, The coating layer is coagulated using the coagulating liquid of (1). By doing so, the entire coating layer can be uniformly solidified to the inside, so that not only the strength of the coating layer is improved but also a recording medium having excellent ink absorbency can be manufactured. Further, since an alkaline coagulation liquid is used, the pH of the surface of the ink jet recording medium can be increased without performing any special treatment. If the surface pH is high, the color development of the dye ink (particularly, cyan) is excellent and preferable. The preferred surface pH is 5.0 or higher, more preferably 6.0 or higher. The surface pH is measured according to Japan TAPPI NO.49. As a simple method, the measurement may be performed using a paper surface pH meter (manufactured by Kyoritsu Riken Co., Ltd.).
In order to improve the surface properties of the ink receiving layer, the pH of the coating liquid needs to be 4.0 or less, and the pH of the coagulation liquid is preferably 8.0 or more.

The pH of the coating solution and coagulating solution of the present invention can be adjusted using various acidic aqueous solutions and alkaline aqueous solutions.
Hydrochloric acid, acetic acid and the like can be used as the acidic aqueous solution. As the alkaline aqueous solution, an aqueous solution of ammonia, sodium hydrogen carbonate, sodium carbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, or the like can be used.

It is preferable that the ink receiving layer in the present invention contains a cationic pigment. In the present invention, since the coating liquid is acidic, the dispersibility of the cationic pigment is also improved. Cationic pigments used in the present invention, alumina, alumina sol, cationic colloidal silica, silica-alumina composite, such as a slurry stabilized with a cationic resin silica described in JP-A-2000-239536, Pigment whose surface is cationic or surface modified cationically. By containing a cationic pigment in the ink receiving layer,
The interaction between the dye in the ink and the cationic pigment improves the water resistance of the image recorded with the dye ink.

Further, in the present invention, a thickener is further provided.
Defoaming agents, foam inhibitors, pigment dispersants, release agents, foaming agents, pH adjusters, surface sizing agents, coloring dyes, coloring pigments, fluorescent dyes,
UV absorbers, antioxidants, light stabilizers, preservatives, water resistance agents, dye fixing agents, surfactants, wet paper strength enhancers, etc.
It can be appropriately added to the ink receiving layer as long as the effects of the present invention are not impaired.

Means for providing the ink receiving layer on the support include known coating devices such as various blade coaters, roll coaters, air knife coaters, bar coaters, curtain coaters, gravure coaters, gate roll coaters, and short dwell coaters. Can be used on-machine or off-machine. According to these methods, a coating layer is coated and coagulated as is known, and then the coating layer is pressed against a heated mirror-finished metal surface, and simultaneously dried to impart gloss to the coating layer surface. . by this,
A good 75 degree specular glossiness measured according to JIS P8142 can be obtained.

[0017]

According to the present invention, there is provided an ink jet recording medium comprising:
Since the outermost layer has a cast coat layer containing polyvinyl alcohol as the ink receiving layer, it has a high glossy surface. Therefore, since the ink absorption is good, the ink jet recording medium is excellent in printing effect.

EXAMPLES Hereinafter, the specific structure of the ink jet recording medium of the present invention will be described with reference to examples, and its characteristics will be described in comparison with comparative examples. However, the present invention is not limited thereto. . In the examples, “parts” and “%” are “parts by weight” unless otherwise specified.
And "% by weight".

[0018]Fabrication of support  Beat 100 parts of hardwood kraft pulp (L-BKP)
Pulp with a freeness of 350 mlcsf
4 parts of Cium, 1 part of cationized starch, polyacrylia
0.3 parts of amide, 0.5 parts of alkyl ketene dimer emulsion
Is added, and after making a paper using a Fourdrinier paper machine in a conventional manner,
Pre-dry, then 5% phosphorylated starch and po
Dry 0.5% liquid of vinyl alcohol with a size press
4g / m dry weight²Apply so that it becomes
100g / m²Support 1
Was. Also, silica (manufactured by Tokuyama, X6
0) 100 parts and polyvinyl alcohol (Kuraray manufacture,
PVA117) Coating solution consisting of 30 parts and having a solid content of 20%
With a coating amount of 12 g / m²With a bar coater
Coating was performed to obtain a support 2.

Embodiment 1 FIG.Preparation of coating liquid  Powder alumina as a pigment (AKP-G01, manufactured by Sumitomo Chemical Co., Ltd.)
5) 60 parts, and alumina sol (Nissan Chemical, Aluminazo
520) 40 parts were dispersed in water, and adjusted to pH 3.7 with acetic acid.
After conditioning, polyvinyl alcohol (Kuraray Co., PVA
217, saponification degree 88%) 10 parts, boric acid 1 part, and
Aqueous coating with 0.5% solids content and 25% solids content
A liquid was prepared. The pH of this coating solution was 3.8.

The above-mentioned coating solution is applied using a comma coater.
Coating amount is 18g / m²Coated on one side of support 1
After that, it is coagulated with the following coagulation liquid, and the coating layer is in a wet state
, Pressed on a mirror surface heated to 100 ° C and dried
To produce cast coated paper.Preparation of coagulation liquid  Remove 0.5% solution of release agent (Nopcoat SYC) with ammonia
To prepare a coagulation solution adjusted to pH 8.0.

Embodiment 2 FIG. 120 g of dry silica having a specific surface area of 300 m ² / g (manufactured by Tokuyama, Leolosil QS30)
880 g of pure water was added thereto, and the mixture was subjected to a dispersion treatment with a homogenizer (Ultra Turrax, T-25, manufactured by Squid) to obtain a silica slurry. To this silica slurry, 48 g of an aqueous solution of diallyldimethylammonium chloride-acrylamide copolymer having a concentration of 25% by weight as a cationic resin was added, and the mixture was stirred with a propeller mixer to obtain a preliminary mixed solution. Using a high-pressure homogenizer (manufactured by Nanomizer, Nanomizer LA-31), the obtained premixed liquid was treated at a processing pressure of 800 kgf / cm.
^The pH is increased by passing once through the orifice at 2.
Thus, a cationic resin-modified silica dispersion liquid No. 5 was obtained. To 100 parts of the solid content of the obtained silica dispersion, polyvinyl alcohol (manufactured by Kuraray Co., PVA117, saponification degree 98.
5%), 10 parts of boric acid, and 0.5 part of an antifoaming agent were added to prepare an aqueous coating liquid having a solid content of 25%. The pH of this coating solution was 3.0.

[0022] The above coating liquid is applied using a comma coater.
Coating amount is 18g / m²Coated on one side of support 1
After that, coagulation treatment is performed using the following coagulation liquid to make the coating layer wet.
While it is in the wet state, it is pressed against the mirror surface heated to 100 ° C,
Dried to produce cast coated paper.Preparation of coagulation liquid  Remove 0.5% solution of release agent (Nopcoat SYC) with ammonia
To prepare a coagulation solution adjusted to pH 8.0.

Comparative Example 1Preparation of coating liquid  Powder alumina as a pigment (AKP-G01, manufactured by Sumitomo Chemical Co., Ltd.)
5) and alumina sol (Nissan Chemical, alumina sol 52)
0) was mixed and dispersed at a ratio of 60 parts to 40 parts, pH 4.7.
Of polyvinyl alcohol (Kuraray, PV
A217) 10 parts, boric acid 1 part and defoamer 0.5 part
This was added to prepare an aqueous coating solution having a solid content of 25%.
The pH of the above coating solution was 4.8. This coating liquid
Since the entire coating liquid gelled, coating could not be performed.
Just coated paper could not be obtained.

Comparative Example 2Preparation of coating liquid  Powder alumina as a pigment (AKP-G01, manufactured by Sumitomo Chemical Co., Ltd.)
5) and alumina sol (Nissan Chemical, alumina sol 52)
0) was dispersed in water at a ratio of 60 parts to 40 parts, and the pH was adjusted with acetic acid.
After adjusting to 3.7, polyvinyl alcohol (Kuraray)
, PVA217) 10 parts, boric acid 1 part, and defoamer
Add 0.5 part, and apply an aqueous coating liquid having a solid concentration of 25%.
Prepared. The pH of this coating solution was 3.8.

[0025] The above coating solution is applied using a comma coater.
Coating amount is 18g / m²Coated on one side of support 1
After that, it is coagulated with the following coagulation liquid, and the coating layer is in a wet state
, Pressed on a mirror surface heated to 100 ° C and dried
To produce cast coated paper.Preparation of coagulation liquid  Remove 0.5% solution of release agent (Nopcoat SYC) with ammonia
To prepare a coagulation liquid adjusted to pH 7.0. In this case
Showed no problem with the stability and suitability of the coating solution.
However, due to poor coagulation, cast coated paper
No usable product was obtained.

Comparative Example 3Preparation of coating liquid  Powder alumina as a pigment (AKP-G01, manufactured by Sumitomo Chemical Co., Ltd.)
5) and alumina sol (Nissan Chemical, alumina sol 52)
0) was mixed and dispersed at a ratio of 60 parts to 40 parts, pH 4.7.
Of polyvinyl alcohol (Kuraray, PV
A217) 10 parts and 0.5 part of an antifoaming agent were added, and solid
An aqueous coating solution having a concentration of 25% was prepared. P of this coating liquid
H was 4.8.

The above-mentioned coating solution is applied using a comma coater.
Coating amount is 18g / m²Coated on one side of support 1
After that, it is coagulated with the following coagulation liquid, and the coating layer is in a wet state
, Pressed on a mirror surface heated to 100 ° C and dried
To produce cast coated paper.Preparation of coagulation liquid  2% boric acid and 0.5% release agent (Nopcoat SYC)
The solution was adjusted (pH 5.5) to produce a coagulation solution.

Embodiment 3 FIG.Preparation of coating liquid  Polyvinyl alcohol (C) adjusted to pH 3.0 with acetic acid
Rare PVA117) solution with polyvinyl alcohol
1 part of boric acid and 0.5 part of antifoam
Further, an aqueous coating solution having a solid content of 12% was prepared. this
The pH of the coating solution was 3.0.

This coating solution was applied using a comma coater.
Work volume is 8g / m²Was applied to one side of the support 2 so that
Then, the coating layer is coagulated with the following coagulating liquid to make the coating layer wet.
In the meantime, press it on the mirror surface heated to 100 ° C and dry it
Cast coated paper was manufactured.Preparation of coagulation liquid  Remove 0.5% solution of release agent (Nopcoat SYC) with ammonia
To prepare a coagulation solution adjusted to pH 8.0.

Comparative Example 4Preparation of coating liquid  Polyvinyl alcohol (Kuraray, PVA117) solution
Water with 0.5% of defoamer added thereto and a solid concentration of 12%
An aqueous coating solution was prepared. The pH of this coating solution was 6.8.
Was.

The coating solution was applied using a comma coater.
Work volume is 8g / m²Was applied to one side of the support 2 so that
Then, the coating layer is coagulated with the following coagulating liquid to make the coating layer wet.
In the meantime, press it on the mirror surface heated to 100 ° C and dry it
Cast coated paper was manufactured.Preparation of coagulation liquid  Remove 0.5% solution of release agent (Nopcoat SYC) with ammonia
To prepare a coagulation solution adjusted to pH 8.0.

The treatment methods of Examples 1 to 3 and Comparative Examples 3 and 4 are summarized in Table 1 below.

[Table 1]

The results of the evaluation of the continuous operability and the surface strength of the coating layer in Examples and Comparative Examples according to the following evaluation criteria are as shown in Table 2.

[Table 2]

However, each evaluation item in the table was evaluated as follows. i) Surface glossiness of coating layer: Regarding the surface of the coating layer, which is the greatest feature of cast coated paper, JIS P-81
According to No. 42, 75 ° specular gloss was measured and evaluated. ii) Water resistance: ISO / JIS- of Japan Standards Association
Image of SCID bicycle (N5) is PM800C (EPS)
ON), and after one hour, ion-exchanged water was dropped on the clock to visually evaluate the water resistance. ：: Level at which the clock face can be read. ×: The level at which the clock face cannot be read.

Iii) Print quality (ink absorption): Water resistance: ISO / JIS-SCI of the Japan Standards Association
D Image of bicycle (N5)
And the watch was visually evaluated. ：: Level at which both the hands of the clock and the numbers on the dial can be read. ○: The level on the clock face cannot be decoded, but the hands can be decoded. Δ: The number on the clock face cannot be decoded, but the hands can be decoded. ×: The level at which the numbers and hands on the clock face cannot be read.

As is clear from Tables 1 and 2, it was proved that the ink jet recording medium of the present invention has excellent ink jet recording characteristics and excellent gloss.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Yasuda 5-21-1 Oji, Kita-ku, Tokyo F-term in Nippon Paper Industries Co., Ltd. F-term (reference) 2C056 EA05 FC06 2H086 BA02 BA16 BA31 BA33 BA34

Claims (3)

[Claims] Claims: 1. An acidic coating solution containing polyvinyl alcohol and boric acid and / or borate having a pH of 4.0 or less is applied to at least one surface of a support to form a coating layer. The coating layer is coagulated using an alkaline coagulating liquid, and while the coating layer is in a wet state, the coating layer is pressed against a heated mirror-finished metal surface to give a gloss to the coating layer surface. A method for producing an ink jet recording medium, which is provided. 2. The method for producing an ink jet recording medium according to claim 1, wherein the coating liquid further contains a cationic pigment. 3. The ink jet printer according to claim 1, wherein one or more ink receiving layers are provided between the support and the coating layer containing polyvinyl alcohol and boric acid and / or borate. Manufacturing method of recording medium.