JPH10167706A - Compound inorganic fine powder and it utilization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compound inorganic fine powder excellent in absorbency and fixity of ink, further to provide a material to be recorded containing the compound inorganic fine powder in an ink-receiving layer and further to provide paper for recording (synthetic paper) hardly causing color-sinking. SOLUTION: This compound inorganic fine powder is obtained by using a particle having hydroxyl group as a nucleus 1, and coating the surface of the nucleus with a shell 2 of an aluminum compound selected from aluminum oxide and aluminum hydroxide. A material to be recorded is formed by forming a coating layer of a resin containing 40-92wt.% compound inorganic fine powder and 60-8wt.% resin binder on a surface of a supporter. A synthetic paper is obtained by stretching a resin film comprising 8-65wt.% compound inorganic fine powder and 92-35wt.% thermoplastic resin at a temperature lower than a melting point of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel composite inorganic fine powder particle in which a particle having a hydroxyl group is a nucleus and the entire surface is covered with a shell of an aluminum compound. This composite inorganic fine powder is used as a filler for an ink receiving layer provided on the surface of a support of aqueous inkjet recording paper, or a resin filler such as a synthetic paper, a resin hollow container, a resin injection molded housing, and a pigment coating. It is useful as a filler for paper (high quality paper).

[0002]

2. Description of the Related Art Ink jet recording is a recording system using an aqueous ink in which a dye is dissolved in water. In recent years, its high speed, low noise, easy multicolor printing, great flexibility in recording patterns, and image and fixing have been developed. Is unnecessary, etc.
It is rapidly spreading in various applications, including a hard copy device for color graphic information including kanji. further,
Images formed by the multi-color ink jet method are comparable to those obtained by ordinary multi-color printing, for example, offset printing, and when the number of copies is small, the cost is lower than that of the normal plate making method. Attempts have been made to apply this technology not only to recording but also to the fields of multicolor printing and color photography.

Efforts have been made in terms of ink jet recording apparatuses and ink compositions to use plain paper, pigment coated paper, and synthetic paper as recording media. However, with the improvement of the performance of the inkjet recording apparatus and the expansion of applications such as high-speed, high-definition, and full-color apparatuses, more advanced characteristics are required for the recording medium. The ink receiving layer of the aqueous ink jet recording paper is prepared by mixing an inorganic fine powder with a water-soluble or water-dispersible resin binder (JP-A-55-51683, 62-17418).
No. 2, JP-A-3-284978, JP-A-7-49
No. 89216) was dried, and as the inorganic fine powder, colloidal silica, alumina oxide,
Calcium carbonate, calcium silicate, kaolin, titanium oxide and the like are known.

The ink-adsorbing particles have a high penetration rate of the recording liquid into the particles (that is, a high drying speed of the recording material).
It is preferable to use porous silica particles having a large internal porosity, and to use porous silica powder and alumina sol. On the other hand, in order to improve the color developability of the recording liquid (ink), it is desirable to fix the ink containing the dye and pigment only on the particle surface. It is fixed, and the color developability is a problem. The present inventors have tried to treat the surface of the porous particles with a higher fatty acid or a fatty acid bisamide to reduce the fixing of the ink inside the particles, but found that the drying speed was conversely reduced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite inorganic fine powder having excellent adsorbability and excellent ink fixability. Another object of the present invention is to provide a recording material containing the composite inorganic fine powder in an ink receiving layer. The third aspect of the present invention is a printing paper (synthetic paper) free from color bleeding.
The purpose is to provide.

[0006]

Means for Solving the Problems A first aspect of the present invention is a composite inorganic material having particles having hydroxyl groups as nuclei and the surface of which is covered with a shell of an aluminum compound selected from aluminum oxide and aluminum hydroxide. It provides a fine powder. A second aspect of the present invention is to allow an aluminum alkoxide represented by the following general formula (1) dissolved in a hydrophilic solvent to be adsorbed on a water-containing hydroxyl group-containing particle, so that aluminum hydroxide or aluminum is formed on the surface of the hydroxyl group-containing particle. After forming the oxide film, the hydrophilic solvent is then volatilized and, if necessary, heated at 80 to 600 ° C. The present invention provides a method for producing a composite inorganic fine powder coated with an aluminum shell selected from the following.

R ¹ _(3-n) Al (OR ² ) _n (1) (wherein R ¹ and R ² each independently have 1 to 1 carbon atoms)
And n is an integer of 1 to 3. A third aspect of the present invention is that the above-mentioned composite inorganic fine powder and the resin binder are coated on the surface of the support in an amount of 40 to 92% by weight and a resin binder of 60 to
An object of the present invention is to provide a recording material provided with a resin coating layer containing 8% by weight. A fourth aspect of the present invention is that the composite inorganic fine powder is 8 to 65% by weight and the thermoplastic resin is 92 to 3%.
An object of the present invention is to provide a synthetic paper obtained by stretching a resin film containing 5% by weight at a temperature lower than the melting point of the thermoplastic resin.

[0008]

In the composite inorganic fine powder of the present invention, the nuclei of the particles having a hydroxyl group are entirely covered with the shell of the aluminum compound, so that the dye or pigment in the recording liquid or ink is coated on the surface of the composite inorganic fine powder. And the color is sharpened. Since the shell is generally a porous aluminum compound, it provides voids for the recording liquid and the ink to penetrate, thereby increasing the penetration of the recording liquid and the ink into the particles, and thus increasing the drying rate. Furthermore, in the case of synthetic paper, fine voids are formed inside the stretched film by the stretching with the composite inorganic fine powder as a nucleus, opacity is improved, density is reduced and lightened, and fine cracks are formed on the surface of the stretched film. Because of the formation of the cracks and the presence of the composite inorganic fine powder, the transferability, drying property, and adhesion of the recording liquid and ink (offset ink, gravure ink, melt-type thermal transfer ink, hot-melt inkjet ink, etc.) are improved. improves.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The composite inorganic fine powder of the present invention will be described below. I. Composite inorganic fine powder The composite inorganic fine powder of the present invention is a composite inorganic fine powder having particles having hydroxyl groups as nuclei, the surface of which is covered with a shell of an aluminum oxide selected from aluminum oxide and aluminum oxide. . In general, the adsorption surface area of the inorganic fine powder is larger than the adsorption surface area of the core-containing particles having hydroxyl groups before being coated.

Such composite inorganic fine particles contain a trace amount of water having an average particle size of 0.1 to 5 μm, preferably 0.8 to 3 μm, and a BET adsorption area of 0.5 to 600 m ² / g. And a particle having a hydroxyl group, or a particle having a hydroxyl group is dispersed in a hydrophilic solvent containing a trace amount of water, and a solution obtained by dissolving an aluminum alkoxide represented by the following general formula (I) in a hydrophilic solvent is added thereto. Aluminum alkoxide is adsorbed on the particles having a hydroxyl group to form a film of aluminum hydroxide or aluminum oxide on the surface of the particles having a hydroxyl group. Thereafter, the hydrophilic solvent is volatilized, and the mixture is heated at 80 to 600 ° C. if necessary. It is manufactured by

R ¹ _(3-n) Al (OR ² ) _n (1) (wherein, R ¹ and R ² each independently have 1 to 1 carbon atoms)
And n is an integer of 1 to 3. The particles having a hydroxyl group used in the present invention are defined as having an average particle size of 0.1 to 5 μm, preferably 0.8 to 3 μm,
Inorganic fine particles having a hydroxyl group in the molecular structure and having an adsorption area of 0.5 to 600 m ² / g by the ET method. Specific examples of such particles having a hydroxyl group include magnesium hydroxide, aluminum hydroxide, dawsonite [NaAl (OH) ₂
CO ₃ ], montmorillonite [Al ₄ (Mg)
[Si ₈ (Al) O ₂₀ ] (OH) ₄ xH ₂ O, basic magnesium aluminum hydroxy carbonate hydrate [Mg ₆ Al ₂ (OH) ₁₆ CO ₃
.4H ₂ O], natural or synthetic hydrotalcite [Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O],
Inorganic fine particles such as calcite (3CaO.Al ₂ O ₃ .6H ₂ O), alumina hydroxide / magnesium coprecipitate, aluminum hydroxide / sodium carbonate coprecipitate, anhydrous calcium hydrogen phosphate and the like. Furthermore, hydroxyl groups such as crosslinked fine particles of methyl methacrylate and 2-hydroxyethyl methacrylate copolymer, crosslinked fine particles of styrene and 2-hydroxyethyl methacrylate copolymer, and crosslinked fine particles of polystyrene / ethylene glycol diacrylate copolymer are used. Organic polymer particles having the same can also be used.

In the method for producing composite inorganic fine particles,
When the hydrophilic solvent contains 0.0001 to 5% by weight of water, the addition of water is unnecessary. The particles having hydroxyl groups dispersed in the hydrophilic solvent adsorb water in the hydrophilic solvent as a desiccant, and the aluminum alkoxide is hydrolyzed and polymerized by the water adsorbed on the particles having hydroxyl groups, and the hydroxyl groups of the particles having hydroxyl groups. (Reaction proceeds on the surface of the hydroxyl group-containing particles), whereby a porous layer of aluminum oxide and aluminum hydroxide is formed on the surface of the hydroxyl group-containing particles.

In this case, particles of aluminum oxide or aluminum hydroxide alone are not formed. When magnesium hydroxide is used as the hydroxyl-containing particles and aluminum triisopropoxide is used as the aluminum alkoxide (see Example 1), the reaction is represented by the following formula.

[0014]

Embedded image

Here, Mg (OH) ₂ of [3] is Mg-O on the surface of magnesium hydroxide which is a particle having a hydroxyl group.
H is described as a representative, and may be a hydroxy group on the particle surface or the inner surface. The H ₂ O of [1] is contained in or absorbed by the particles having a hydroxyl group. Therefore, in the present invention, the hydrolysis of the aluminum alkoxide is carried out on the surface of the particle having a hydroxyl group. Proceeding, the obtained particles having a multilayer structure have a structure in which particles having hydroxyl groups are nuclei, and the entire surface of the nuclei is covered with a shell of a film of aluminum hydroxide and / or aluminum oxide.

Examples of the hydrophilic solvent include methanol, ethanol, 1-propanol, 2-propanol, isobutyl alcohol, tert-butyl alcohol, dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, anisole, phenetole, and methoxytoluene. , Dioxane, trioxane, furan, 2-methylfuran, tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-
Hexanone, methyl isobutyl ketone, methyl acetate, ethyl acetate, propyl acetate, formamide, methylformamide, dimethylformamide are used alone or in combination of two or more. Preferably, tetrahydrofuran, butanol, isopropyl alcohol, ethyl alcohol, dimethylformamide, dimethyl ether, diethyl ether, methyl ethyl ether and the like are mentioned.

Examples of the aluminum alkoxide include aluminum triisopropoxide, aluminum diethyl monoisopropoxide, aluminum ethyl diisopropoxide, aluminum tributoxide, aluminum methyl ethyl isopropoxide, aluminum ethyl diethoxide, aluminum triethoxide, Examples thereof include aluminum ethyl dibutoxide, aluminum isopropyl diethoxide, aluminum methyl diethoxide, aluminum dibutyl ethoxide, and aluminum diisopropyl methoxide.

In order to obtain the composite inorganic fine powder having a core / shell structure according to the present invention, water acting as a catalyst is adsorbed on the surface of the core particles before the particles having hydroxyl groups of the core contact and react with the aluminum alkoxide. It is necessary to be. In order to adsorb such water to particles having a hydroxyl group serving as a nucleus, the nucleus particles are immersed in water to pull up the nucleus particles,
The core particles are dispersed or immersed in a hydrophilic solvent containing water, and the water in the hydrophilic solvent is adsorbed on the core hydroxyl group-containing particles by utilizing the water adsorption action of the core particles.

The amount of water adsorbed on 100 parts by weight of the particles having a hydroxyl group is 0.01 to 10 parts by weight, preferably 0.5 to 10 parts by weight.
-5 parts by weight. In order to make the reaction between the aluminum alkoxide and the water-adsorbed particles having hydroxyl groups uniform, the aluminum alkoxide is dissolved in a hydrophilic solvent and brought into contact with the aluminum alkoxide. The amount of the aluminum alkoxide is in the range of 1 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of the particles having a hydroxyl group. The hydrophilic solvent is 80 parts by weight based on 100 parts by weight of the particles having a hydroxyl group.
To 2,000 parts by weight, preferably 200 to 1,100 parts by weight.

The reaction temperature between the water-adsorbed particles having hydroxyl groups and the aluminum alkoxide is -30 ° C to 95 ° C.
° C, preferably from 0 to 90 ° C. After the reaction, the hydrophilic solvent is dried or evaporated under reduced pressure.
Heat to ℃ to complete drying. The aluminum hydroxide may be converted to aluminum oxide by the heating and drying. The adsorption surface area of the thus obtained composite inorganic fine powder having a core / shell structure of the present invention is larger than the adsorption surface area of the core, and the adsorption surface area by the BET method is 1 to 1,000 m.
² / g, preferably ² to 800 m ² / g, and the particle size is 0.5 to 7 μm, preferably 1 to 5 μm.

As shown in the schematic diagram of FIG. 1, the entire surface of the particle having the core hydroxyl group is covered with a porous film of aluminum hydroxide or aluminum oxide. In FIG. 1, 1 is a nucleus of a particle having a hydroxyl group,
1a is a void that may or may not be present, 2 is a shell of aluminum hydroxide and / or aluminum oxide, 2
a is a void existing in the shell. If the hydroxyl group-containing particles before contact with the aluminum alkoxide do not adsorb moisture, the film does not cover the entire surface of the hydroxyl group-containing particles (see Comparative Examples 2 and 3), and the ink is sufficiently adsorbed on the particle surface. As a result, the ink may flow out around the particles, causing bleeding, or causing lack of clarity of the ink.

II. On the surface of a support such as pulp paper, synthetic paper, salt-white film, polyethylene terephthalate or the like, 40 to 92% by weight, preferably 60 to 92% by weight of the composite inorganic fine powder of the present invention having a core / shell structure is used.
A recording paper provided with a coating layer (aqueous ink-receiving layer) containing 90% by weight and a resin binder of 60 to 8% by weight, preferably 40 to 10% by weight includes aqueous inkjet recording paper, hot melt type inkjet recording paper, And excellent in ink transfer and drying properties, and clear printed and printed images.

As the inorganic fine powder, the composite inorganic fine powder having a core / shell structure of the present invention may be used alone, or may be used.
The weight percent or less may be replaced by powders such as calcium carbonate, clay, titanium oxide, zinc oxide, and talc. As the resin binder, styrene / maleic anhydride copolymer,
Styrene / acrylic acid alkyl ester copolymer, polyvinyl alcohol, ethylene / vinyl alcohol copolymer containing silanol group, polyvinylpyrrolidone, ethylene / vinyl acetate copolymer, methyl ethyl cellulose, sodium polyacrylate, starch, polyethylene polyamine, polyester , Polyacrylamide, vinylpyrrolidone / vinyl acetate copolymer, cation-modified polyurethane resin, tertiary nitrogen-containing acrylic resin (JP-A-62-1)
No. 48292) and the like.

If necessary, the coating layer may contain an ink setting agent, an ultraviolet absorber, a surfactant and the like. Examples of the ink setting agent include a tertiary ammonium salt of polyethyleneimine, an acrylic copolymer containing a quaternary ammonium group as a copolymerization component, and an epichlorohydrin adduct of polyamine polyamide. The coating layer is formed on the support by applying the coating agent containing the inorganic fine powder and the resin binder on the surface of the support so that the solid content is ² to 50 g / m ² , preferably 5 to 30 g / m ^2. And dried.
The thickness of the support is 30 to 250 μm, preferably 60 to 1 μm.
50 μm. If necessary, apply a supercalender treatment to the surface of the dried coating layer to form a coating layer (ink receiving layer)
Is smoothed.

III. Synthetic paper Resin containing 8 to 65% by weight, preferably 10 to 55% by weight, and 92 to 35% by weight, preferably 90 to 45% by weight of a thermoplastic resin of the present invention. By stretching a film based on the composition at a temperature lower than the melting point of the thermoplastic resin, a synthetic paper having fine voids (voids) inside the stretched film can be obtained.

Such synthetic paper is a microporous synthetic paper comprising a stretched resin film of a thermoplastic resin such as polypropylene, high-density polyethylene, polyethylene terephthalate, polycarbonate, and the like, and a stretched resin film having fine voids inside the film. , Its opacity (JIS
P-8138) is 85% or more, preferably 90% or more, and the porosity calculated by the following formula (1) is 10 to 60%;
The thickness is preferably 15 to 45%, the thickness is 30 to 300 μm, preferably 50 to 150 μm, and the density is 0.60 to 1.
Microporous synthetic paper having a weight of 12 g / m ² can be used.

[0027]

(Equation 1)

As the inorganic fine powder, the composite inorganic fine powder of the present invention having a core / shell structure may be used alone, or another inorganic fine powder may be used in combination. Other inorganic fine powders such as calcium carbonate, calcined clay, silica, diatomaceous earth, talc, titanium oxide, barium sulfate, etc., having a particle size of 0.03 to 5
Micron ones are used. The synthetic paper may have a single-layer structure or a multi-layer structure in which other layers are stacked. Examples of such microporous synthetic paper include the following. Here, the inorganic fine powder of the surface layer of the synthetic paper contains the composite inorganic fine powder of the core / shell structure of the present invention, and the production method of the prior art document described as a reference is the same as the inorganic fine powder. They differ in that a composite inorganic fine powder having a core / shell structure is not described in these documents.

A biaxially stretched thermoplastic resin biaxially-stretched film containing inorganic fine powder in a ratio of 8 to 65% by weight (Japanese Patent Publication No. 54-31032, US Pat. No. 37)
No. 75521, U.S. Pat. No. 4,191,719, U.S. Pat. No. 4,377,616). Synthetic paper using a biaxially stretched thermoplastic film as a base layer and a uniaxially stretched thermoplastic resin film containing from 8 to 65% by weight of inorganic fine powder as a paper-like layer (JP-B-46-4079).
No. 4, JP-A-57-149363, and JP-A-57-149363.
No. 181829).

This synthetic paper has a three-layer structure in which a paper-like layer of a uniaxially stretched film exists on the front and back surfaces of the base material layer even if it has a two-layer structure (Japanese Patent Publication No. 46-40794, US Patent No. 43).
18950), three to seven layers of synthetic paper in which another resin film layer exists between the paper-like layer and the base layer (Japanese Patent Publication No. 50-29738, Japanese Patent Application Laid-Open No. 57-14936).
No. 3, No. 56-126155, No. 57-18
No. 1829, US Pat. No. 4,472,227)
Even if the back surface is a metal salt of a propylene / ethylene copolymer or an ethylene / (meth) acrylic acid copolymer (Na,
It may be a synthetic paper having three or more layers having a heat seal layer made of a resin having a lower melting point than the base layer resin such as Li, Zn, K) and chlorinated polyethylene (Japanese Patent Publication No. 3-1397).
No. 3).

The method for producing a synthetic paper having a three-layer structure is, for example, as follows.
A thermoplastic resin film containing 0 to 30% by weight, preferably 8 to 25% by weight of an inorganic fine powder is uniaxially stretched at a temperature lower than the melting point of the resin on both sides of a uniaxially oriented film. 8 to 65% by weight of inorganic fine powder
A laminated film of a thermoplastic resin to be contained is laminated, and then the laminated film is stretched in a direction perpendicular to the above-mentioned direction. In the resultant synthetic paper, the paper-like layer is uniaxially oriented, and fine voids are formed. Is a film having a large number of
The base material layer is a laminated structure oriented biaxially.

The stretching ratio is preferably 4 to 10 times in both the longitudinal and transverse directions.
64 to 167 ° C) and 110 to 162 ° C for high density polyethylene (melting point 121 to 124 ° C).
120 ° C, polyethylene terephthalate (melting point 246 ~
252 ° C.). The stretching speed is 50 to 350 m / min. This synthetic paper can be subjected to gravure printing, offset printing, and screen printing, and provides clear printing with little color sinking.

[0033]

The present invention will be specifically described below with reference to examples and comparative examples. Production Example of Core / Shell Composite Inorganic Fine Powder: (Example 1) Reaction liquid 1 Magnesium hydroxide having an average particle diameter of 0.8 μm and a BET adsorption surface area of 5 m ² / g (Kisuma 5, Kyowa Chemical Industry: trade name) To 100 g, 1,000 g of tetrahydrofuran having a water content of 0.4% by weight was added, and the mixture was stirred in a closed vessel for 8 hours to adsorb water in the solvent to magnesium hydroxide.

Reaction solution 2 10 g of aluminum triisopropoxide (powder)
It was dissolved in 10 g of tetrahydrofuran having a water content of 100 ppm or less. The reaction solution 2 was mixed with the reaction solution 1 and reacted by stirring for 8 hours in a closed vessel. Reaction solution 2 was prepared and mixed within 30 minutes before mixing. After the reaction, the solvent, tetrahydrofuran, was volatilized by an evaporator, and the particles were further dried under vacuum at 150 ° C. until a constant weight was obtained, whereby particles having a particle size of 2.3 μm were obtained.

Table 1 shows the measurement results of the adsorption surface area by the BET method. ASAP2000V2.03 (manufactured by Shimadzu Corporation) was used for the measurement, and nitrogen was used as the adsorption gas. The calculation of the adsorption surface area followed the analysis method of the usual BET method.
That is, in the following BET equation, x is on the horizontal axis and x / is on the vertical axis.
When plotted with (V (1-x)), the slope (C-1) /
A straight line of (V _m C) and an intercept 1 / (V _m C) is obtained, from which V _m and C can be obtained.

X / (V (1-x)) = 1 / (V _m C) +
((C-1) / (V _m C)) xx: relative pressure (= P / P ₀ ) V: adsorption amount (when the relative pressure is x) V _m : single molecule adsorption amount C: constant> 0 Here, x at which good linearity is obtained is 0.05 to 0.
V _m and C were determined in the range of 30. It was determined BET adsorption surface area than the V _m. In the following Examples and Comparative Examples,
Similarly, the BET adsorption surface area was measured and calculated.

The atomic composition of the surface-treated magnesium hydroxide particles was analyzed by EDX. The following apparatus was used for the analysis. EDX: EMAX-5770-W, manufactured by HORIBA, Ltd. SEM: S-2460N, manufactured by Hitachi, Ltd. Analysis results of the surface-treated magnesium hydroxide particles and the magnesium hydroxide particles not subjected to the surface treatment shown in Example 1 By comparison, it can be seen that the surface-treated magnesium hydroxide particles of Example 1 are formed of a composite of magnesium hydroxide particles, aluminum oxide, and aluminum hydroxide.

However, in this analysis, no knowledge can be obtained as to whether an aluminum oxide or aluminum hydroxide layer is formed on the surface. Therefore, EDX analysis of the cut surface of the present particles was performed. For the sample, the particles were embedded in a phenol resin and cut with a microtome. EDX-ray analysis confirmed that aluminum oxide and aluminum hydroxide layers were formed only on the surface. From the above, it was shown that the surface-treated particles of this example had an aluminum oxide and aluminum hydroxide layer on the surface and had a larger adsorption surface area than the particles having a hydroxyl group before the treatment.

Comparative Example 1 In this comparative example, magnesium hydroxide (Kisuma 5, manufactured by Kyowa Chemical Industry Co., Ltd.) was used without surface treatment. Table 1 shows the measurement results of the adsorption surface area by the BET method. The measuring method is the same as in Example 1.

Comparative Example 2 Reaction liquid 1 Magnesium hydroxide (Kisuma 5, manufactured by Kyowa Chemical Industry) 10
To 0 g, 1,000 g of n-hexane was added, and the mixture was stirred in a sealed container for 8 hours. Reaction liquid 2 n to 10 g of aluminum triisopropoxide (powder)
-Hexane 10g was added and stirred. Neither the reaction solution 1 nor the reaction solution 2 was dissolved and was uniformly dispersed. Reaction liquid 1
And reaction solution 2 were mixed and stirred, and the reaction was performed in the same manner as in Example 1.
Dried. Table 1 shows the measurement results of the adsorption surface area by the BET method.
Shown in

Comparative Example 3 Reaction liquid 1 Magnesium hydroxide (Kisuma 5, manufactured by Kyowa Chemical Industry) 10
To 0 g, 1,000 g of a 1: 1 mixture of methanol and water was added, and the mixture was stirred in a sealed container for 8 hours. Reaction liquid 2 10 g of a 1: 1 mixture of methanol and water was added to 10 g of aluminum triisopropoxide (powder), followed by stirring.
Neither the reaction solution 1 nor the reaction solution 2 was dissolved and was uniformly dispersed. The reaction solution 1 and the reaction solution 2 were mixed and stirred, reacted and dried in the same manner as in Example 1. Table 1 shows the measurement results of the adsorption surface area by the BET method.

The structure of the treated particles is such that a certain portion of the surface of the magnesium hydroxide particles is covered with an aluminum compound, but the entire surface is not covered.
In addition to the magnesium hydroxide particles, fine particles of aluminum oxide were also found. Example 2 The following reaction solution was prepared. After the preparation of the reaction solution 1, the mixture was stirred for 8 hours or more in a closed container, and the water in the solvent was adsorbed on the porous silica.

Reaction solution 1 100 g of synthetic hydrotalcite (DHT-4A, manufactured by Kyowa Kagaku Kogyo Co., Ltd., moisture content: 0.34%) and 2% by weight of moisture content
Of N, N-dimethylformamide was stirred in a closed vessel. Reaction liquid 2 10 g of aluminum triisopropoxide (powder) was dissolved in 500 g of N, N-dimethylformamide having a water content of 100 ppm or less.

The reaction solution 2 was mixed with the reaction solution 1 and reacted for 8 hours in a closed vessel. The reaction solution 2 was adjusted and mixed within 30 minutes before mixing. The reaction solution and the solvent were volatilized with an evaporator, and further dried at 200 ° C. under vacuum until a constant weight was obtained. Table 1 shows the measurement results of the adsorption surface area by the BET method. EDX analysis was performed in the same manner as in Example 1, and it was confirmed that an aluminum oxide and aluminum hydroxide layer was formed on the hydrotalcite surface.

Table 1 Adsorption area by BET adsorption (m ² / g) Example 1 87 Comparative Example 1 5 Comparative Example 2 7.6 Comparative Example 3 7.1 Example 2 79

IV. Production Example of Synthetic Paper: (Example 3) (1) Polypropylene 80 with MFR of 1.0 g / 10 min
After kneading a composition (A) obtained by mixing 2% by weight of high-density polyethylene and 18% by weight of calcium carbonate having an average particle size of 1.5 μm with an extruder set at 240 ° C.,
It was extruded into a sheet and cooled by a cooling device to obtain a non-stretched sheet. After the sheet was heated again to a temperature of 140 ° C., it was stretched 4.5 times in the machine direction.

(2) A composition (B) obtained by mixing 80% by weight of polypropylene having an MFR of 4.0 g / 10 minutes and 20% by weight of the core / shell composite particles obtained in Example 1 was placed in another extruder. After kneading, extrude this into a sheet from a die,
This is laminated on both sides of the 4.5-fold stretched film of (1),
A three-layer laminated film was obtained. Next, after cooling the three-layered laminated film to 60 ° C., about 160 ° C.
Heat to a temperature of 7 ° C and use a tenter to
Stretched twice and annealed at a temperature of 165 ° C.
After cooling to a temperature of 0 ° C. and corona discharge treatment, the ears were slit, and the three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching) had a thickness of 105 μm (B / A / B = 20 μm / 6
5 μm / 20 μm), a synthetic paper having a whiteness of 95% and an opacity of 94% was obtained. The void ratio of each layer is (B / A / B
= 28% / 32% / 28%). Furthermore, Beck smoothness (JIS P-81) of the surface layer (B) of this synthetic paper
19) was 200 seconds.

Comparative Example 4 (1) Polypropylene 80 having an MFR of 1.0 g / 10 min
After kneading a composition (A) obtained by mixing 2% by weight of high-density polyethylene and 18% by weight of calcium carbonate having an average particle size of 1.5 μm with an extruder set at 240 ° C.,
It was extruded into a sheet and cooled by a cooling device to obtain a non-stretched sheet. After the sheet was heated again to a temperature of 140 ° C., it was stretched 4.5 times in the machine direction.

(2) A composition (B) in which 80% by weight of polypropylene having an MFR of 4.0 g / 10 minutes and 20% by weight of magnesium hydroxide particles of Comparative Example 1 were mixed was kneaded by another extruder. Thereafter, this was extruded into a sheet from a die, and this was laminated on both sides of the 4.5-fold stretched film of (1) to obtain a laminated film having a three-layer structure. Next, the three-layer laminated film was cooled to 60 ° C.
After heating to a temperature of 60 ° C., stretching in a transverse direction 7 times using a tenter, annealing at a temperature of 165 ° C., cooling to a temperature of 60 ° C., and performing a corona discharge treatment. Slit to have a three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching) with a thickness of 105 μm (B / A / B = 20 μm).
m / 65 μm / 20 μm), whiteness 95%, opacity 9
2% of synthetic paper was obtained. The void ratio of each layer is (B / A
/ B = 24% / 32% / 24%). Further, the Beck smoothness (JIS P-
8119) was 380 seconds.

The surface of the synthetic paper obtained in Example 3 and Comparative Example 4 was solid-printed with gravure red ink, and the obtained printed surface was magnified 100 times with an electron microscope.
Although the synthetic paper of Example 3 had almost perfect halftone dots and a clear red color, the synthetic paper of Comparative Example 4 lacked about 25% of halftone dots as compared with the synthetic paper of Example 4 and had some color sinking. Was found.

Example 4 One side of a pulp papermaking paper having a basis weight of 150 g / m ² was coated with a coating composition for an ink receiving layer having the following composition so that the solid content was 30 g / m ² . After drying, a smoothing treatment was performed with a super calender to obtain a recording paper. Coating composition: 100 parts by weight of composite inorganic fine powder of Example 1 30 parts by weight of polyvinyl alcohol 10 parts by weight of polyethyleneimine quaternary ammonium salt 5 parts by weight of sodium polyacrylate Water 1600 parts by weight Aqueous inkjet manufactured by Canon Inc. Using a printer, color printing of yellow, magenta, cyan, and black was performed on the ink receiving layer of the recording paper, and the time until the ink dried was examined.

Then, after confirming that the color development was sufficient for all the colors, an adhesive tape “Cellotape” (trade name) manufactured by Nichiban Co., Ltd. was strongly applied to a part of the printed recording paper on the printing surface. The adhesive tape was adhered, and then the adhesive tape was quickly peeled off along the adhesive surface, and the degree of ink remaining on the paper surface was visually determined. Table 2 shows the results.

(Comparative Example 5) Recording paper was obtained and evaluated in the same manner as in Example 4 except that a coating composition having the following composition was used as a coating composition for the ink receiving layer. Coating composition: 100 parts by weight of magnesium hydroxide (Kisuma 5) 30 parts by weight of polyvinyl alcohol 10 parts by weight of polyethylenimine quaternary ammonium salt 5 parts by weight of sodium polyacrylate Water 1600 parts by weight The results are shown in Table 2.

(Comparative Example 6) Recording paper was obtained and evaluated in the same manner as in Example 4, except that a coating composition having the following composition was used as a coating composition for the ink receiving layer. Coating composition: 100 parts by weight of inorganic fine powder of Comparative Example 3 30 parts by weight of polyvinyl alcohol 10 parts by weight of polyethylenimine quaternary ammonium salt 5 parts by weight of sodium polyacrylate Water 1600 parts by weight The results are shown in Table 2.

Example 5 Recording paper was obtained and evaluated in the same manner as in Example 4 except that a coating composition having the following composition was used as a coating composition for the ink receiving layer. Coating agent composition: Composite inorganic fine powder of Example 2 100 parts by weight Polyvinyl alcohol 30 parts by weight Polyethyleneimine quaternary ammonium salt 10 parts by weight Sodium polyacrylate 5 parts by weight Water 1600 parts by weight The results are shown in Table 2.

[0056]

[Table 2]

(Example 6) The recording paper obtained in Example 4
Phase change made by Sony Tektronix, Inc.
Inkjet color printer “Phaser
300IS "(trade name) and hot-melt inks of the company, such as black ink (016-1123-00), cyan ink (016-1124-00), magenta ink (016-1125-00) and yellow ink (016) (1126-00), and ink jet printing was performed by jetting at an ink melting temperature (78 to 85 ° C.) (Evaluation) (1) Solid uniform printability: yellow, magenta, cyan,
Observation of the degree of uniformity of the solid portion developed with the black color ink using an optical microscope with a magnification of 100 times revealed a clear image without any omission in the solid portion.

[0058]

According to the present invention, it is possible to obtain a recording paper which can obtain a composite image and prints by obtaining a composite inorganic fine powder with good ink fixation.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a model structure of a composite inorganic fine powder having a core / shell structure of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 5/18 C08J 5/18 D21H 19/38 C01F 7/02 A // C01F 7/02 D21H 1/22 B B29K 503: 04

Claims (5)

[Claims] 1. A composite inorganic fine powder comprising particles having hydroxyl groups as nuclei and the surface of which is covered with a shell of an aluminum compound selected from aluminum oxide and aluminum hydroxide. 2. A method for adsorbing aluminum alkoxide represented by the following general formula (1) dissolved in a hydrophilic solvent to particles containing water and having a hydroxyl group, so that aluminum hydroxide or After forming the aluminum oxide film, the hydrophilic solvent is then volatilized, and if necessary, heated at 80 to 600 ° C., with the core being particles having hydroxyl groups, the surface of which is aluminum oxide, aluminum water A method for producing a composite inorganic fine powder coated with an aluminum shell selected from oxides. R ¹ _(3-n) Al (OR ² ) _n (1) (wherein R ¹ and R ² each independently have 1 to 1 carbon atoms)
And n is an integer of 1 to 3. ) 3. The method according to claim 1, wherein the hydrophilic solvent is methanol, ethanol, 1-propanol, 2-propanol, isobutyl alcohol, tert-butyl alcohol, dimethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, anisole.
Phenetol, methoxytoluene, dioxane, trioxane, furan, 2-methylfuran, tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, methyl acetate, ethyl acetate 3. The production method according to claim 2, wherein the production method is selected from acetic acid, propyl acetate, formamide, methylformamide, and dimethylformamide. 4. A recording material comprising a support and a resin coating layer containing 40 to 92% by weight of the composite inorganic fine powder according to claim 1 and 60 to 8% by weight of a resin binder. 5. The composite inorganic fine powder according to claim 1,
A synthetic paper obtained by stretching a resin film containing 65% by weight and 92 to 35% by weight of a thermoplastic resin at a temperature lower than the melting point of the thermoplastic resin.