JP2008006390A - Liquid dispersion of alumina amide and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide liquid dispersion of alumina amide, having excellent dispersion stability in spite of not containing a hard-to-remove and nonvolatile dispersion stabilizer such as organic sulfonic acid. <P>SOLUTION: The liquid dispersion of alumina amide contains amides (1), alumina fine particle (2) and nitric acid or hydrochloric acid (3) having 0.05-0.30 molar ratio of the nitric acid or hydrochloric acid to the alumina as essential components but does not contain a compound having a sulfonate group, wherein the viscosity of this liquid dispersion having 10 wt.% alumina concentration is ≤600 mPa s when measured at 25°C by using a cone/plate type rotational viscometer (the revolving speed is 30 rpm). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an alumina amide dispersion having excellent dispersion stability and a method for producing the same. In particular, the present invention relates to an alumina amide dispersion that does not contain a non-volatile dispersion stabilizer that is difficult to remove, such as organic sulfonic acid, and a method for producing the same.

  An alumina aqueous dispersion (alumina hydrosol, aqueous alumina sol) in which alumina fine particles are dispersed in water is used as a surface modifying material because it can form an alumina thin film.

  Since the aqueous dispersion of alumina is water, when applied to highly hydrophobic substrates such as plastic, it is difficult to apply because the wettability to the substrate is poor, and the adhesion between the formed alumina thin film and the substrate is also good. It is insufficient. Moreover, since water resistance is also inferior, it becomes a problem depending on a use. In many cases, the aqueous dispersion of alumina alone cannot achieve the target substrate modification. In order to improve these, a binder, a surfactant or the like may be used in combination.

  However, when applying an aqueous alumina dispersion, the binder must be water soluble. Therefore, the binders that can be used are limited, and improvement is often insufficient.

  As one means for solving this problem, a sol (alumina organosol) in which alumina hydrate is dispersed in various organic solvents has been studied.

  However, the dispersion stability is insufficient, and the viscosity and gelation may be easily caused.

  In order to improve the dispersion stability of the alumina organosol, a method of adding a dispersion stabilizer is known.

Japanese Patent Publication No. 2003-517418 (Patent Document 1) discloses a method for producing a metal oxide dispersible in an organic solvent, which is modified with an organic sulfonic acid. Table 1 of the publication describes organosols in which alumina modified with organic sulfonic acid is dispersed in ethylene glycol. Although the dispersion stability of the alumina organosol is improved by the modification with the organic sulfonic acid, the remaining organic sulfonic acid may have an adverse effect depending on the application. Furthermore, there is a problem that a complicated process is required to remove the organic sulfonic acid. This is a common problem when trying to improve the dispersion stability of an organosol by adding a substance having a dispersion stabilizing action such as a chelating agent or a polymer dispersant, not limited to organic sulfonic acids.
Special table 2003-517418 gazette

  The problem to be solved by the present invention is to provide an alumina amide dispersion excellent in dispersion stability and a method for producing the same without adding a non-volatile dispersion stabilizer that is difficult to remove such as organic sulfonic acid.

  As a result of intensive studies to solve the above problems, the present inventor has obtained a non-volatile dispersion stabilizer that is difficult to remove, such as organic sulfonic acid, from an alumina amide dispersion containing a specific amount of nitric acid or hydrochloric acid. Based on this finding, the present invention has been completed.

That is, the alumina amide dispersion of the present invention is
(1) Amides,
(2) Alumina fine particles and (3) Conical plate type rotation containing 0.05 to 0.30 mole times nitric acid or hydrochloric acid as an essential component with respect to alumina and not containing a compound having a sulfonic acid group The viscosity of the dispersion having an alumina concentration of 10% by weight measured at 25 ° C. with a viscometer (rotation speed: 30 rpm) is 600 mPa · s or less.

  Further, in the alumina amide dispersion of the present invention, preferably, the amides are formamide, dimethylformamide, acetamide, dimethylacetamide, formylpiperidine, acetylpiperidine, N-methylpiperidone, urea, tetramethylurea, ethyleneurea and 1,3- It is at least one amide selected from the group consisting of dimethylethyleneurea.

  The alumina amide dispersion of the present invention is preferably characterized in that the alumina fine particles are boehmite or pseudoboehmite.

  In the method for producing an alumina amide dispersion of the present invention, an alumina slurry obtained by hydrolyzing metal aluminum or a hydrolyzable aluminum compound is peptized in the presence of a specific amount of acid to obtain an alumina aqueous dispersion, When the amides are substituted with a solvent to obtain an alumina amide dispersion, pulverization is carried out at 60 to 160 ° C. in the presence of nitric acid or hydrochloric acid 0.06 to 0.3 mol times the amount of alumina. It is what.

  The method for producing an alumina amide dispersion of the present invention is preferably characterized in that the hydrolyzable aluminum compound is an aluminum alkoxide.

  More preferably, the method for producing an alumina amide dispersion of the present invention is characterized in that the solvent replacement of the aqueous alumina dispersion with amides is carried out at 60 ° C. or lower.

  Since the aluminaamide dispersion of the present invention is excellent in dispersion stability, it is difficult to thicken or gelate, and it is easy to handle because of its low viscosity. In addition, since it does not contain non-volatile dispersion stabilizers that are difficult to remove, such as organic sulfonic acids, there is little risk of adverse effects even when used in various applications.

  The alumina amide dispersion of the present invention will be described below.

  In the alumina amide dispersion of the present invention, alumina fine particles are dispersed in amides containing a specific amount of nitric acid or hydrochloric acid.

  Examples of amides that are dispersion media include various aliphatic carboxylic acid amides, N-lower alkyl group-substituted aliphatic carboxylic acid amides, N, N′-lower alkyl group-substituted aliphatic carboxylic acid amides, urea, N, N ′. -Lower alkyl group-substituted urea, lactams, N-lower acyl nitrogen-containing heterocyclic compounds, 1,3-dialkylethyleneurea and the like are included. Preferably, at least one amide selected from the group consisting of formamide, dimethylformamide, acetamide, dimethylacetamide, formylpiperidine, acetylpiperidine, N-methylpiperidone, urea, tetramethylurea, ethyleneurea and 1,3-dimethylethyleneurea It is. From the viewpoint of safety, dimethylacetamide is particularly preferable.

  The alumina fine particles in the present invention include aluminum hydroxide (alumina hydrate) such as gibbsite, bayerite, boehmite, suspected boehmite, diaspore, amorphous, and γ, η, δ, ρ, κ, θ, χ, α. Forms of alumina crystals are included.

  Preferably, the alumina fine particles are boehmite or pseudoboehmite.

  The amount of nitric acid or hydrochloric acid contained in the alumina amide dispersion of the present invention is 0.05 to 0.30 mol times, preferably 0.08 to 0.20 mol times relative to alumina. When the content of nitric acid or hydrochloric acid is less than 0.05 mol times, gelation or precipitation is likely to occur, and when it exceeds 0.30 mol times, the stability over time is lowered, which is not preferable.

  The alumina concentration, viscosity, and transmittance of the alumina amide dispersion of the present invention are as follows.

Alumina concentration: 5.0 to 15.0% by weight
・ Moisture: 1% or less (Karl Fischer method)
・ Initial viscosity: 600 mPa · s or less Viscosity after 30 days: 600 mPa · s or less Cone / plate type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., RE115R type, cone angle: 1 ° 34 ′, plate diameter: 24 mm) It measured on condition of this.
Plate temperature: 25 ° C, rotation speed: 30rpm
-Transmittance: 90-97%
Transmittance after 30 days: 90-97%
The transmittance at 540 nm was measured with a spectrophotometer (Hitachi, Ltd., V-3000). The viscosity of the aluminaamide dispersion of the present invention is 600 mP · s or less, and the change with time is small. When it exceeds 600 mP · s, the operability of the alumina amide dispersion is deteriorated.

  A method for producing the alumina amide dispersion of the present invention will be described.

  The alumina amide dispersion of the present invention is obtained by peptizing an alumina slurry obtained by hydrolyzing metal aluminum or a hydrolyzable aluminum compound in the presence of a specific amount of acid to obtain an alumina aqueous dispersion, It can be obtained by solvent substitution.

  The hydrolyzable aluminum compound includes various inorganic aluminum compounds and aluminum compounds having an organic group. Examples of inorganic aluminum compounds include salts of inorganic acids such as aluminum chloride and aluminum sulfate, aluminates such as sodium aluminate, and aluminum hydroxide. Examples of the aluminum compound having an organic group include carboxylates such as aluminum acetate, aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, and other aluminum alkoxides, cyclic aluminum oligomers, diisopropoxy ( Examples thereof include aluminum chelates such as ethylacetoacetate) aluminum and tris (ethylacetoacetate) aluminum, and organoaluminum compounds such as alkylaluminum. Aluminum alkoxides are preferable because they have moderate hydrolyzability and easy removal of by-products, and those having an alkoxyl group having 2 to 5 carbon atoms are particularly preferable.

  The amount of water in the hydrolysis is preferably 15 to 50 mol with respect to 1 mol of aluminum alkoxide. If the amount is less than 15 mol, the yield is low, and if it exceeds 50 mol, the viscosity increases during hydrolysis, making it difficult to operate.

  The hydrolysis is preferably carried out at 95 ° C. or lower for 0.2 to 3 hours. If it exceeds 95 ° C, bumping is likely to occur, which is not preferable. When water and aluminum alkoxide come into contact with each other, the temperature of the liquid rises. However, as the hydrolysis proceeds, alcohol is by-produced, and the temperature of the reaction liquid decreases, so that it does not rise above the boiling point of the alcohol. Therefore, since the growth of the alumina hydrate particles becomes slow, the alcohol is removed by heating to around 95 ° C. If the time is less than 0.2 hours, it is difficult to control the temperature, and heating for more than 3 hours is not preferable because it only increases the process time.

  Next, the alumina slurry obtained by hydrolysis is peptized by heating at a high temperature in the presence of a specific amount of acid.

  As the acid, nitric acid or hydrochloric acid is preferable, and nitric acid is particularly preferable.

  The coexistence amount of nitric acid or hydrochloric acid is 0.05 to 0.3 mol times, preferably 0.08 to 0.2 mol times relative to alumina. When it is less than 0.05 mol times, peptization does not proceed sufficiently, and the intended sol cannot be obtained. When it exceeds 0.3 mol times, stability with time decreases, which is not preferable.

  The optimum amount of nitric acid or hydrochloric acid to coexist at the time of peptization varies depending on the type of organic solvent to be replaced with water.

  The acid coexisting at the time of peptization may be added at the time of hydrolysis, but the acid lost when removing the alcohol by-produced by hydrolysis is added again so that the amount falls within the specified range. There is a need.

  It heats at 60-160 degreeC for 0.5 to 10 hours, Preferably it hydrothermally processes at 80-130 degreeC for 1 to 6 hours. When the temperature is lower than 60 ° C., it takes a long time for peptization, and even if it is carried out at a temperature exceeding 160 ° C., the increase in the peptization rate is slight. When the time is less than 0.5 hours, peptization is insufficient, and heating for more than 10 hours only increases the process time, which is not preferable.

  Next, amide is added to the alumina aqueous dispersion obtained by peptization so that the desired alumina solid content concentration is obtained, and the solvent is replaced. The alumina amide-water dispersion can be dehydrated with an ultrafiltration membrane or the like, but can be easily made into an amide dispersion by heating and concentration.

  When the solvent is replaced by concentration by heating, dehydration is preferably performed at 60 ° C. or lower under reduced pressure. When dehydrated at 60 ° C. or higher, it tends to thicken and gel.

  Next, examples will be shown and described in more detail, but the present invention is not limited to these examples.

  In order to investigate the crystal form of the dispersed alumina fine particles, a sample obtained by removing the solvent with an evaporator and pulverizing was measured with an X-ray diffractometer (RINT2000 model, manufactured by Rigaku Corporation).

(Example 1)
Into a 1 L autoclave, 230 g (12.8 mol) of ion exchange water was charged, and the temperature was raised to 70 ° C. while stirring. 88 g (0.43 mol) of aluminum isopropoxide was added dropwise over 1 hour, the liquid temperature was gradually raised to 95 ° C., and the generated 2-propanol was distilled off. Peptization was performed by adding 4.0 g (0.04 mol) of 61% nitric acid and stirring at 95 ° C. for 3 hours. 330 g of N, N-dimethylacetamide (hereinafter referred to as DMAC) was added to the obtained aqueous alumina dispersion, and water (containing DMAC) was distilled off under reduced pressure at 50 to 60 ° C. until the alumina concentration was 10%. Got. Alumina concentration: 10.2% by weight, viscosity: 28 mPa · s, moisture: 0.6%, transmittance: 95% (540 nm), and average particle size was 0.01 μm. Changes in viscosity and transmittance over time are shown in [Table 1].

(Example 2)
Into a 1 L autoclave, 230 g (12.8 mol) of ion exchange water was charged, and the temperature was raised to 70 ° C. while stirring. 88 g (0.43 mol) of aluminum isopropoxide was added dropwise over 1 hour, the liquid temperature was gradually raised to 95 ° C., and the generated 2-propanol was distilled off. Peptization was carried out by adding 4.8 g (0.047 mol) of 61% nitric acid and stirring at 95 ° C. for 3 hours. 330 g of N, N-dimethylformamide (hereinafter DMF) was added to the resulting aqueous alumina dispersion, and water (containing DMAC) was distilled off under reduced pressure at 50 to 60 ° C. until the alumina concentration reached 10%. Got. Alumina concentration: 9.9% by weight, viscosity: 7 mPa · s, moisture: 0.6%, transmittance: 96% (540 nm), and average particle size was 0.01 μm. Changes in viscosity and transmittance over time are shown in [Table 1].

(Comparative Example 1)
Into a 1 L autoclave, 230 g (12.8 mol) of ion exchange water was charged, and the temperature was raised to 70 ° C. while stirring. 88 g (0.43 mol) of aluminum isopropoxide was added dropwise over 1 hour, the liquid temperature was gradually raised to 95 ° C., and the generated 2-propanol was distilled off. Peptization was performed by adding 15.5 g (0.15 mol) of 61% nitric acid and stirring at 95 ° C. for 2 hours. 330 g of DMAC was added to the resulting aqueous alumina dispersion, and water was distilled off at 50-60 ° C. under reduced pressure. However, the viscosity increased during dehydration and gelled in the middle. The viscosity could not be measured.

(Comparative Example 2)
Into a 1 L autoclave, 230 g (12.8 mol) of ion exchange water was charged, and the temperature was raised to 70 ° C. while stirring. 88 g (0.43 mol) of aluminum isopropoxide was added dropwise over 1 hour, the liquid temperature was gradually raised to 95 ° C., and the generated 2-propanol was distilled off. Peptization was performed by adding 5.3 g (0.05 mol) of 61% nitric acid and stirring at 170 ° C. for 2 hours. 330 g of DMAC was added to the resulting aqueous alumina dispersion, and water was distilled off at 50-60 ° C. under reduced pressure. However, the viscosity increased during dehydration and gelled in the middle. The viscosity could not be measured.

(Comparative Example 3)
A 1 L autoclave was charged with 230 g (12.8 mol) of ion-exchanged water, and the temperature was raised to 70 ° C. while stirring. 88 g (0.43 mol) of aluminum isopropoxide was added dropwise over 1 hour, the liquid temperature was gradually raised to 95 ° C., and the generated 2-propanol was distilled off. Peptization was performed by adding 4.4 g (0.043 mol) of 61% nitric acid and stirring at 100 ° C. for 2 hours. 220 g of ethylene glycol was added to the obtained aqueous alumina dispersion, and water was distilled off at 50-60 ° C. under reduced pressure. However, the viscosity increased during dehydration and gelled in the middle, resulting in a cone-plate rotary viscometer. The viscosity could not be measured.

Note 1: Molar transmittance of acid added to alumina: Hitachi spectrophotometer V-3000 Measurement wavelength: 540 nm
Viscosity: Toki Sangyo Co., Ltd. Cone / Plate type rotational viscometer: RE115R

  Aluminamide dispersion with improved stability over time without containing a dispersion stabilizer is useful as a surface treatment agent for plastics such as polyester, and is used for printing and recording materials, pharmaceuticals, foods, and other industries that require gas barrier properties. Packaging materials for materials, plastic electrical and electronic parts that require flame retardancy, automotive parts materials, and plastic coating materials for agricultural houses and tunnels that require transparency, anti-fogging properties, and water resistance Useful as a modifier.

Claims (6)

(1) Amides,
(2) Alumina fine particles and (3) Conical plate type rotation containing 0.05 to 0.30 mole times nitric acid or hydrochloric acid as an essential component with respect to alumina and not containing a compound having a sulfonic acid group An alumina amide dispersion characterized in that the viscosity of a dispersion having an alumina concentration of 10% by weight measured at 25 ° C. with a viscometer (rotation speed: 30 rpm) is 600 mPa · s or less. At least one amide selected from the group consisting of formamide, dimethylformamide, acetamide, dimethylacetamide, formylpiperidine, acetylpiperidine, N-methylpiperidone, urea, tetramethylurea, ethyleneurea and 1,3-dimethylethyleneurea; The alumina amide dispersion according to claim 1, wherein The alumina amide dispersion according to claim 1 or 2, wherein the alumina fine particles are boehmite or pseudoboehmite. Alumina slurry obtained by hydrolyzing metal aluminum or hydrolyzable aluminum compound is peptized in the presence of a specific amount of acid to form an alumina aqueous dispersion, followed by solvent substitution with amides to obtain an alumina amide dispersion 4. The peptization is carried out at 60 to 160 ° C. in the presence of 0.05 to 0.3 moles of nitric acid or hydrochloric acid with respect to alumina. The manufacturing method of the alumina amide dispersion liquid as described in 2. above. The method for producing an alumina amide dispersion according to claim 4, wherein the hydrolyzable aluminum compound is an aluminum alkoxide. 6. The method for producing an alumina amide dispersion according to claim 4, wherein the solvent substitution of the amides in the aqueous alumina dispersion is carried out at 60 ° C. or less.