JP2000318308A - Recording medium and manufacture of recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glossy recording medium which is excellent in ink absorbing capacity and has a high image density, and a method of manufacturing the recording medium. SOLUTION: This recording medium is constituted by providing an ink receiving layer on a base. The ink receiving layer contains γalumina and a binder. The surface glossiness of the ink receiving layer is 50% or higher by a measurement at 75 deg.. The average particle diameter of the γ alumina is 0.21 μm or higher and 1.0 μm or lower, and 90% or higher of the whole particles of the γalumina have a particle diameter of 1.0 μm or lower. This method for manufacturing the recording medium comprises a step wherein after crushing γ alumina, the coarse particle component is removed by separation and a step wherein the γ alumina of which the coarse particle component has been removed is applied to the base together with a binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a recording medium and an ink jet recording method using the same.

[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 adhere to a recording medium such as paper to record images and characters. It has features such as easy multi-coloring, great flexibility in recording patterns, and no need for development. It can be applied to printers, copiers, word processors, FAs, etc.
It has been spread to information devices such as X and plotters, and is rapidly spreading.

In recent years, high-performance digital cameras, digital videos, and scanners have been provided at low cost, and with the spread of personal computers, the opportunity to output image information obtained from them by the ink jet recording system has been increasing. .

For this purpose, recording apparatuses and recording methods have been improved such as high-speed recording, high-definition recording, and full-color recording. However, advanced characteristics have also been required for recording media. .

[0005] Regarding recording media used for ink-jet recording or the like, various recording media have been conventionally proposed. For example, JP-A-52-53012 discloses that
An inkjet paper in which a low-size base paper is infiltrated with a surface treatment paint is disclosed. JP-A-53-49113
Japanese Patent Application Publication No. JP-A-2005-64131 discloses an inkjet paper in which a sheet containing a urea-formalin resin powder is impregnated with a water-soluble polymer. JP-A-55-5830 discloses an ink-jet recording sheet provided with an ink-absorbing coating layer on the surface of a support, and JP-A-55-51583 discloses an amorphous recording medium as a pigment in a coating layer. An example using silica is disclosed, and JP-A-55-146786 discloses an example using a water-soluble polymer coating layer.

[0006] In recent years, a recording medium using alumina hydrate has attracted attention. Because alumina hydrate has a positive charge, it has advantages over conventional recording media, such as good fixation of the ink dye, high color development, and an image.

For example, US Pat. Nos. 4,879,166 and 5,104,730, JP-A-2-276670, JP-A-4-37576, and JP-A-5-32037 disclose:
A recording medium in which a layer containing alumina hydrate having a pseudo-boehmite structure is used as an ink receiving layer is disclosed. These pseudoboehmite can be produced by a known method such as hydrolysis of aluminum alkoxide and hydrolysis of sodium aluminate. Further, in the case of a recording medium prepared by using the pseudo-boehmite prepared therefrom as a coating liquid, an image can be obtained with better fixation of the ink dye and higher color development than a conventional recording medium.

On the other hand, JP-A-10-129112 describes an ink jet recording sheet using aluminum oxide fine particles of a γ-type crystal form having an average particle diameter of 200 nm or less.

[0009]

The present inventors have paid attention to γ-alumina, but with a conventional recording medium containing γ-alumina as a main component, it was possible to obtain only an image having low gloss.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a glossy recording medium having excellent ink absorbency and high image density, and a method of manufacturing the recording medium. The purpose is to do.

The recording medium of the present invention has an ink receiving layer provided on a base material. The ink receiving layer contains γ-alumina and a binder, and the ink receiving layer has a surface glossiness of 75%.
It is characterized by being 50% or more in the measurement of °.

This recording medium has an average particle diameter of 0.21 μm or more and 1.0 μm, and 90% of all particles of the γ-alumina.
The above is achieved by using γ-alumina having a particle diameter of 1.0 μm or less.

Further, the method for producing a recording medium of the present invention comprises the steps of:
After pulverizing the alumina, there is a step of removing coarse particle components by a separation treatment, and a step of applying the γ-alumina from which the coarse particle components have been removed together with a binder onto a substrate.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The recording medium of the present invention has a γ
It has an ink receiving layer containing alumina and a binder. The gamma alumina used in the present invention has been subjected to a treatment for removing coarse particle components. By using such γ-alumina, it is possible to obtain an ink-receiving layer having an ink-absorbing property, having a glossiness of 50% or more as measured at a surface glossiness of 75 °.

The γ-alumina used in the present invention has an average particle diameter of 0.21 μm or more and 1.0 μm or less, preferably 0.5 μm or less, and 90% or more of the total number of γ-aluminas has a particle diameter of 1.0 μm or less. It is preferable to have one. In the present invention, the particle size distribution is a value measured using a particle size distribution measuring device (trade name: LS230, manufactured by Coulter). When the average particle diameter exceeds 1.0 μm, or when the condition that 90% or more of the total number of γ-aluminas has a particle diameter of 1.0 μm or less is not satisfied, a desired glossiness cannot be obtained.
When the average particle size is smaller than 0.21 μm, high color density and glossiness can be obtained, but the ink absorbency is reduced and the ink may overflow depending on the image.

In the recording medium of the present invention, the binder that can be used in combination with γ-alumina includes:
It can be freely selected from water-soluble polymers. For example, polyvinyl alcohol or a modified product thereof, starch or a modified product thereof, gelatin or a modified product thereof, casein or a modified product thereof, gum arabic, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose and hydroxypropylmethylcellulose, SB
R latex, NBR latex, conjugated diene-based copolymer latex such as methyl methacrylate-butadiene copolymer, functional group-modified polymer latex, vinyl-based copolymer latex such as ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, maleic anhydride Acids, copolymers thereof, and acrylate copolymers are preferred. These binders can be used alone or in combination of two or more.

The mixing ratio of γ-alumina to the binder is preferably 1: 1 to 30: 1 by weight, more preferably 1: 1 to 25: 1. If the amount of the binder is smaller than the above range, the mechanical strength of the ink receiving layer is reduced, and cracks and powder fall may occur. When the amount of the binder is larger than the above range, the pore volume may be reduced, and the absorbability of the ink may be reduced.

Γ-alumina is obtained by heating and calcining boehmite or pseudo-boehmite produced by a known method such as hydrolysis of aluminum alkoxide and sodium aluminate at a temperature of, for example, 400 to 600 ° C. . The γ-alumina thus formed usually has a particle size on the order of μm. In the present invention, such gamma alumina is treated to remove gamma alumina having a large particle diameter. As the γ-alumina before the treatment, those having primary particles in the form of flakes or needles are preferred. Γ-alumina obtained by treating this type of γ-alumina has high ink absorbency and dye fixability, and is unlikely to crack when a film is formed. Commercially available γ-alumina can be used as a starting material.
For example, AKP-015 of Sumitomo Chemical Co., Ltd. can be used.

The treatment for removing gamma alumina having a large particle diameter is performed as follows.

First, gamma alumina as a starting material is dispersed in pure water while stirring. Since these γ-alumina usually have a particle diameter of more than 1 μm, they tend to settle if left without stirring. If necessary, a dispersant may be used. As the dispersant, acids such as hydrochloric acid, nitric acid, and acetic acid, and surfactants are preferable.

Thereafter, a crushing process is performed. In the crushing process,
Ultrasonic treatment, homogenizer treatment, nanomizer treatment and the like can be used.

Finally, coarse particles of the order of μm are removed by a separation treatment. As the method, a method of collecting the supernatant by static sedimentation, a method of centrifugation, a method using a filter such as ultrafiltration, or the like can be used.

The coating liquid for forming the ink receiving layer contains, in addition to γ-alumina and a binder, a dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, if necessary. It is also possible to add an antifoaming agent, a waterproofing agent, a release agent, a fluorescent whitening agent, an ultraviolet absorber, an antioxidant and the like.

The base material of the fibrous substance used in the present invention is a base material mainly composed of wood pulp and a filler, and weighs 120 g / m ^{2 in} order to give a texture like a silver salt photograph.
The above-mentioned ones are preferable, and those having a range of 150 to 180 g / m ² are preferable because a high-quality recording medium can be provided even in the size of A4 size and A3 size. In addition, the degree of Stekicht is preferably 100 seconds or more,
More preferably, it is desirable to use one for 200 seconds or more. This is almost done in the layer containing γ-alumina with respect to the ink absorbency, so that the substrate itself does not require much absorbency. Rather, it is necessary to improve the back surface, cross section, and the like.

In order to improve the whiteness of the substrate, it is preferable to form a layer containing barium sulfate on at least one surface of the substrate. The coating amount on the substrate is preferably in the range of 20 to 40 g / m ^{2 in} order to impart smoothness. The method of coating and drying is not particularly limited, but it is preferable that a surface smoothing treatment such as a calendar is performed as a finishing step, the whiteness is 87% or more, and the Beck smoothness of the surface is 400 seconds or more.

In the recording medium having an ink receiving layer of the present invention, as a method of forming the ink receiving layer on the substrate, the above-mentioned dispersion solution containing γ-alumina is applied to the substrate using a coating apparatus, A drying method can be used.
As a coating method, a coating technique using a commonly used blade coater, air knife coater, roll coater, curtain coater, bar coater, gravure coater, spray device, or the like can be used. The coating amount of the dispersion solution is 0.5 to 60 g / m ² , more preferably 5 to 45 g / m ² in terms of dry solid content. If necessary, the surface smoothness of the ink receiving layer can be improved by using a calender device or the like after coating.

[0027]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The measurement of physical properties was performed by the following methods.

(1) Particle Size Distribution A reagent was prepared by adding 2 cc of a dispersion of γ-alumina to 50 cc of pure water, and measurement was carried out using an LS230 particle size distribution analyzer manufactured by Coulter Corporation.

(2) Image Density With respect to the ink having the following ink composition 1, each image density of an image solid printed with Y, M, and CBk inks was evaluated using a Macbeth reflection densitometer RD-918.

(3) Surface Gloss Evaluation was performed using a digital variable-angle gloss meter (manufactured by Suga Test Instruments Co., Ltd.).

(Ink composition) Dye 5 parts Ethylene glycol 10 parts Polyethylene glycol 10 parts Water 75 parts (dye) Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 199 Bk: C.I. I. Food black 2

Example 1 US Pat. No. 4,242,271
No. 4,202,870, aluminum octoxide was synthesized and then hydrolyzed to produce an alumina slurry. Thereafter, post-treatments such as drying were performed to obtain powdery pseudo-boehmite. Put this in a 500 ° C oven
Calcination was performed for a time to obtain γ-alumina. The median particle size distribution at this time was 20 μm. This γ-alumina was dispersed in pure water at a concentration of 20 wt% using acetic acid as a dispersant. Then, after treating with an ultrasonic disperser for 60 minutes, coarse particles were removed by centrifugation to obtain a γ-alumina-treated product. Table 1 shows the data of gamma alumina after the treatment.

In order to measure the glossiness of a recording medium containing this γ-alumina-treated product as a main component, a γ-alumina-treated product and a polyvinyl alcohol solution (PVA117 (product: manufactured by Kuraray Co., Ltd.)) And the solid content of polyvinyl alcohol were mixed and stirred at a weight mixing ratio of 10: 1 to obtain a dispersion.

The above dispersion was bar-coated on a substrate having a basis weight of 150 g / m ² and a Beck smoothness of 200 seconds and a Beck smoothness of 420 seconds so as to have a dry thickness of about 40 g / m ² to obtain a recording medium 1. Was.

The surface of the recording medium had gloss. Table 1 shows the optical density and glossiness of this recording medium.

Example 2 AKP-G was used as gamma alumina.
A recording medium 2 was prepared and tested in the same manner as in Example 1 except that 015 (product: Sumitomo Chemical Co., Ltd.) was used. The median particle size distribution of AKP-G015 as a starting material was 2.4 μm. Table 1 shows the data of gamma alumina after the treatment. This recording medium 2 also had a glossiness. Table 1 shows the optical density and glossiness of this recording medium.

Comparative Example 1 A recording medium 3 was produced in the same manner as in Example 1 except that AKPG015 used in Example 2 was used without treatment as γ-alumina. Table 1 shows the data of gamma alumina after the treatment. The optical density and glossiness of the recording medium were measured. The measured values are shown in Table 1. No surface gloss was observed.

Comparative Example 2 AKP- used in Example 2
Except that G015 was only processed by an ultrasonic disperser,
A recording medium 4 was prepared in the same manner as in Example 1. Table 1 shows the data of gamma alumina after the treatment. The optical density and glossiness of the recording medium were measured. The measured values are shown in Table 1. The glossiness of the surface was somewhat visible but not very large.

(Comparative Example 3) A recording medium 5 was prepared in the same manner as in Example 1 except that the γ-alumina used in Example 1 was subjected only to the treatment with an ultrasonic disperser. Table 1 shows the data of gamma alumina after the treatment. The optical density and glossiness of the recording medium were measured.
The measured values are shown in Table 1. No surface gloss was observed.

[0040]

[Table 1]

[0041]

Since the recording medium of the present invention has a glossy ink receiving layer and uses γ-alumina from which coarse particles have been removed, it has excellent ink absorption and obtains a high-density image. The recording medium which can be manufactured can be manufactured.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyuki Hosoi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kenji Onuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside the corporation

Claims (4)

[Claims] 1. A recording medium having an ink receiving layer on a substrate, wherein the ink receiving layer contains γ-alumina and a binder, and the surface glossiness of the ink receiving layer is 50% or more as measured at 75 °. A recording medium characterized by the above-mentioned. 2. The γ-alumina has an average particle size of 0.21 μm.
2. The recording medium according to claim 1, which has a particle diameter of not less than m and not more than 1.0 μm, and 90% or more of all the particles of the γ-alumina have a particle diameter of not more than 1.0 μm. 3. The substrate according to claim 1, wherein the fibrous sheet is provided with a coating layer containing barium sulfate on the surface thereof, and the surface has a Beck smoothness of 400 seconds or more and a whiteness of 87% or more. Item 2. The recording medium according to Item 1. 4. The method according to claim 1, further comprising: after pulverizing the γ-alumina, removing a coarse particle component by a separation treatment; and coating the γ-alumina from which the coarse particle component has been removed with a binder onto a substrate. Manufacturing method of a recording medium to perform