JP3390458B2 - Silica sol - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silica sol having an opal-like free color. 2. Description of the Related Art Japanese Patent Publication No. 1-23411 discloses a method for producing a transparent and stable siliceous sol exhibiting brilliant colors. According to this manufacturing method, 0.2 to 1 μm
The above silica-based sol is produced by preparing an alcohol dispersion liquid exhibiting Tingal scattering using amorphous silica spheres having a particle diameter of m and having a uniform particle diameter, and replacing the alcohol dispersion medium with a nonpolar solvent. Things. Furthermore, the same publication describes the principle of exhibiting glowing color, because particles take a face-centered cubic arrangement in a solvent, and the interval between overlapping arrangement planes is as small as the wavelength of light. The light is separated, and as a result of diffracting light of a specific wavelength in a specific direction, a specific monochromatic light is seen, and it is explained that the color changes continuously by changing the position of the eyes. An object of the present invention is to provide a silica sol exhibiting a completely new opal-like free color, instead of the silica sol exhibiting the glow color. [0004] The silica sol of the present invention has an average particle size of 0.1.
It is a silica sol in which silica particles having a coefficient of variation of particle size of 15% or less in a range of 045 to 0.55 μm are dispersed in water or a water-organic solvent, and have an electric conductivity of 560 μS
/ Cm or less. The silica sol preferably exhibits an opal-like play color. DETAILED DESCRIPTION OF THE INVENTION The silica sol of the present invention comprises powder,
It can be produced from various starting materials of silica sol such as sol, and among them, silica particle-dispersed sol such as water-dispersed silica sol and silica organosol is preferable. In the present invention, first, it is necessary to remove contaminating ions (cations and anions) from the silica particle-dispersed sol and to highly deionize the silica sol to stabilize the silica sol. By highly deionizing contaminant ions in the colloid, the electric double layer on the surface of the silica particles expands, and mutual repulsion acts between the particles, so that the dispersion state of the colloid particles is stabilized. In deionization, impurity ions can be removed by subjecting a silica particle-dispersed sol to an ion exchange treatment with a cation exchange resin and an anion exchange resin. Specific treatment methods include passing the sol through a column filled with a cation exchange resin and an anion exchange resin, or mixing and stirring the ion exchange resin in the sol and then separating the resin. An appropriate method is adopted. The degree of deionization can be confirmed by measuring the electric conductivity, and the electric conductivity of the silica sol is determined to be 560 μS / cm.
It is necessary to: In general, silica sol is unstable in a low pH range without OH groups on the surface being dissociated, and becomes a stable silica sol in a high pH range. Therefore, the above-mentioned Tokuhei 1-2
Japanese Patent No. 3411 discloses stabilization of a siliceous sol in a nonpolar solvent on the alkali side. On the other hand, the present invention stabilizes the silica sol by highly deionizing the silica sol as described above. [0009] By deionization, the structure of the silica particle dispersion takes on a structure similar to an aggregate of crystallites (crystallites), and therefore, a phenomenon very similar to a phenomenon called play color inherent to opal is developed. . Opal play in opal refers to the phenomenon in which iridescence is observed inside or on the surface of a mineral, mainly due to the cleavage inside the mineral, parallel to the plane, and the light reflected on the plane being reflected by each other. This is caused by interference. When white light is incident on the silica sol of the present invention, the light is split by the surface of the microcrystal-like structure, light of a specific wavelength is diffracted in a specific direction, and monochromatic light is observed. Since the sol of the present invention has discontinuous planes similar to grain boundaries between microcrystals, diffracted light on individual microcrystal-like structures is different, and various colors of light are observed. A phenomenon appears. The size of the microcrystal-like structure, that is, the size of the play color, varies depending on the size, concentration, concentration of contaminant ions and the like of the silica particles, but is about 7 mm or less, usually about 3 to 6 mm. The play of color phenomenon of the present invention disappears when vibration is applied to the silica sol. However, if the silica sol is allowed to stand still, the color phenomena appear again in a short time. Further, in the stationary state, depending on the properties of the silica sol, the play of color phenomenon may occur continuously or the light may blink. That is, in a region where the mutual repulsion between silica particles is weak, specifically, in a mixed solvent system of a water-organic solvent having a low particle concentration or containing a predetermined amount of salt, the luminescence may sometimes flicker. The dispersion medium of the deionized silica sol includes:
One or a mixture of two or more of water and an organic solvent such as water and an alcohol such as methanol and ethanol, and ethylene glycol can be used. [0013] The concentration of silica particles in the silica sol is 0.1.
The range of 01 to 20% by volume is preferred. If it is lower than 0.01% by volume, the distance between the particles becomes longer and the mutual repulsion does not work. On the other hand, if it is higher than 20% by volume, the mutual repulsive force becomes too strong, and the structure of the dispersion becomes an apparently uniform phase, so that the play-color phenomenon does not appear. The average particle size of the silica particles is preferably 0.55 μm or less, particularly preferably in the range of 0.045 to 0.55 μm. If it is larger than 0.55 μm, the play of color phenomenon cannot be visually observed, and the silica particles tend to settle with the passage of time, and it is difficult to obtain a stable silica sol. On the other hand, 0.
If it is smaller than 045 μm, a clear play color will not be exhibited. The silica particles preferably have a uniform particle size, and a coefficient of variation (CV value) represented by the following equation is preferably 15% or less. CV = (σ / D) × 100 [%] In the above equation, σ: standard deviation, D: average particle diameter. Further, the individual silica particles are monodispersed, and the ratio of the aggregated particles is preferably 10% or less of the total number of particles. The present invention will be described more specifically with reference to the following examples. Example 1 Silica particle dispersion sol having an average particle size of 0.04 μm (catalyst SI-45P, manufactured by Catalyst Chemical Industry Co., Ltd., silica concentration 4)
0% by weight) and 600 g of water glass and 233 of pure water.
It was diluted to 0 g to prepare a seed particle dispersion. This dispersion was heated to 98 ° C., and while maintaining this concentration, a silicic acid solution (silica concentration 4% by weight) was added at 22 g / hr for about 9 hours. After completion of the addition, the mixture was aged at this temperature for 1 hour, cooled, concentrated to an SiO ₂ concentration of 10% by weight with an ultrafiltration membrane, and further concentrated to 20% by weight with an evaporator.
Average particle size 0.06 μm, CV value 6.5%, aggregation rate 1.6
% Silica particles in which monodispersed silica particles were obtained. One part of this sol was taken, a cation exchange resin was added and stirred, and after the pH became 3 or less, the resin was separated by filtration, and then an anion exchange resin was added and stirred. After the pH reached 7, the resin was separated by filtration, and a cation exchange resin was added again to adjust the pH to 2.8. This was aged at 80 ° C. for 10 hours, cooled, and the resin was separated by filtration. When this sol was diluted with pure water to a silica concentration of 0.86% by volume, it became a sol emitting playful colors. This play color disappears when the sol is vibrated, but the play color appears immediately upon standing. Example 2 A silica particle-dispersed sol having an average particle size of 0.10 μm (Cataloid SI-100P, manufactured by Catalyst Chemical Industry Co., Ltd.) was used in Example 1.
And treated with an ion exchange resin. Aging condition 90
When diluted with pure water in the same manner as in Example 1 except that the temperature was changed to 8 ° C. and 8 hours, the same free color was developed. Example 3 In Example 2, when the silica concentration was changed to 6.82% by volume, a play color was developed. The play color of the sol was not affected by the vibration, and always maintained the play color. Example 4 About 30 cc of a mixture of a cation exchange resin and an anion exchange resin was added to 100 g of a silica particle dispersion sol having an average particle size of 0.08 μm (catalyst SI-80P, manufactured by Kasei Kagaku Kogyo KK).
And then aged at 80 ° C. for 10 hours. After cooling, the resin was diluted with pure water without filtration to obtain a silica concentration of 0.86% by volume. Example 5 215 g of spherical silica having an average particle size of 0.08 μm was dispersed in a mixed solution of 1,000 g of ethyl alcohol, 43 g of water, and 357 g of 28% aqueous ammonia to prepare a seed particle dispersion. This seed particle dispersion was placed in an autoclave, heated to 120 ° C., and while maintaining the temperature, 1952 g of a mixed solution of ethyl alcohol / water / ammonia (weight ratio: 1.0 / 0.3 / 0.1) and Ethyl silicate (28% by weight as SiO ₂ ) 369
g was added at the same time. After the whole amount was added, the mixture was aged at 150 ° C. for 1 hour, then concentrated to an SiO ₂ concentration of 10% by weight with an ultrafiltration membrane, further concentrated to 20% by weight with an evaporator, and had an average particle size of 0.11 μm and a CV value of 4%. A silica sol having a monodispersion of 0.2% and silica particles having an agglomeration ratio of 0.2% was obtained. A part of the silica sol is taken, a cation exchange resin is added thereto, and the mixture is stirred. After the pH reaches 3.1, the resin is separated by filtration, and then an anion exchange resin is added, followed by stirring. After the pH reached 7.3, the resin was filtered off. Take about 100 cc of the above silica sol in a beaker, add about 10 cc of a mixture of a cation exchange resin and an anion exchange resin,
When the silica concentration was adjusted to 0.23% by volume by adding distilled water, a sol having a flickering free color was obtained. When the sol was vibrated, the play color disappeared. However, when the sol was allowed to stand, the sol immediately returned to the original blinking sol. Example 6 In Example 5, a cation exchange resin was further added to silica sol treated with a cation exchange resin and an anion exchange resin to adjust the pH to 2.8. This was aged at 90 ° C. for 8 hours and then cooled. This sol was placed in a beaker and diluted with pure water to a silica concentration of 4.35% by volume, whereby a sol having a flickering free color was obtained. This play color disappeared when vibration was applied, but flickered immediately upon standing still. Example 7 A mixture of a cation exchange resin and an anion exchange resin was added to the silica sol obtained in Example 5 before the treatment with the ion exchange resin.
After aging for 1 hour at 0 ° C., the mixture was cooled and left at room temperature for 3 weeks with the resin contained. The resin was separated by filtration, and distilled water was added to make the silica concentration 4.65% by volume. A flashing sol was obtained. Example 8 The same sol after filtering out the same resin as in Example 7 was added with NaCl.
Was added to make a silica concentration of 8.41% by volume and a salt concentration of 2.5 × 10 ⁻⁵ mol / l, and a sol having a flickering free color was obtained. Example 9 In Example 5, a mixture of a cation exchange resin and an anion exchange resin was added to the silica sol treated with the ion exchange resin, and at the same time, purified ethanol and pure water were added to obtain a silica concentration of 0. When a sol of a water / ethanol mixed solvent having a concentration of 0.73% by volume and an ethanol concentration of 30% by volume was used, a blinking free color was developed. Example 10 In Example 9, when the ethanol content was 60% by volume and the silica concentration was 1.31% by volume, a flickering free color appeared. Example 11 In Example 9, when ethanol was set at 60% by volume and silica concentration was set at 3.77% by volume, a flickering free color was developed. Example 12 In Example 9, when the content of ethylene glycol was set to 30% by volume and the silica concentration was set to 0.55% by volume, a flickering free color was developed. Example 13 In Example 9, when the content of ethylene glycol was set to 60% by volume and the concentration of silica was set to 1.02% by volume, a flickering free color was developed. Example 14 A silica particle-dispersed sol having an average particle size of 0.08 μm (Cataloid SI-80P, manufactured by Kako Kagaku Kogyo Co., Ltd.) was treated with an ion-exchange resin in the same manner as in Example 5, and then purified ethanol. And pure water, and further a mixture of a cation exchange resin and an anion exchange resin was added to form a sol of a water / ethanol mixed solvent having a silica concentration of 0.73% by volume and an ethanol concentration of 30% by volume. Color developed. Example 15 A silica particle-dispersed sol having an average particle size of 0.20 μm (Cataloid SI-200P, manufactured by Catalyst Chemical Industry Co., Ltd.) was used in Example 1.
When a sol of a water / ethanol mixed solvent having a silica concentration of 0.73% by volume and an ethanol concentration of 30% by volume was prepared in the same manner as in Example 4, a flickering play color was developed. Example 16 A silica particle-dispersed sol having an average particle size of 0.08 μm (Cataloid SI-80P, manufactured by Catalyst Chemical Industry Co., Ltd.) was used in Example 14.
In the same manner as described above, the silica concentration was 1.74% by volume, the solvent concentration was ethanol 30% by volume, ethylene glycol 30% by volume,
When a sol of a mixed solvent of water / ethanol / ethylene glycol was used, a flickering free color was developed. Example 17 Distilled water was added to the sol after the treatment with the ion exchange resin obtained in Example 5 to adjust the silica concentration to 6.5% by volume.
A sol emitting free color was obtained but did not blink. Example 18 After adjusting the silica concentration to 17% by volume in Example 17,
When a mixture of a cation exchange resin and an anion exchange resin was added, a sol emitting playful color was obtained, but did not blink. Example 19 A mixture of a cation-exchange resin and an anion-exchange resin was added to a silica particle-dispersed sol having an average particle size of 0.16 μm (catalyst SI-160P, manufactured by Kasei Kagaku Co., Ltd.)
After aging for 1 hour, the mixture was cooled and left at room temperature for 2 weeks while containing the resin. The resin was separated by filtration, and distilled water was added to adjust the silica concentration to 0.06% by volume. A sol was obtained. COMPARATIVE EXAMPLE 1 A silica particle-dispersed sol having an average particle size of 0.10 μm (Cataloid SI-100P, manufactured by Catalyst Chemical Industry Co., Ltd.) was placed in a beaker, and diluted with distilled water to a silica concentration of 0.86% by volume. The mixture was stirred and turned into a sol which only turned cloudy, and did not develop free color. COMPARATIVE EXAMPLE 2 A silica particle-dispersed sol having an average particle size of 0.04 μm (Cataloid SI-45P, manufactured by Kasei Kasei Kogyo Co., Ltd.) was deionized in the same manner as in Example 5, purified ethanol was added, and the silica concentration was reduced. A sol of a water / ethanol solvent of 0.73% by volume and 30% by volume of ethanol was prepared. A transparent sol was obtained, but no play was observed. COMPARATIVE EXAMPLE 3 A silica particle-dispersed sol having an average particle size of 0.60 μm (catalyst SI-600P, manufactured by Catalyst Chemical Industry Co., Ltd.) was used in Example 5.
After deionization in the same manner as described above, purified ethanol was added to obtain a sol of a water / ethanol solvent having a silica concentration of 0.73% by volume and ethanol of 30% by volume. A cloudy sol was obtained, but no play was observed. The above Examples and Comparative Examples are shown in Table 1 together with the electrical conductivity of the silica sol. The electric conductivity was measured with a conductivity meter (Toa Denpa Kogyo KK, CM-11P). In the column of play color observation, 色 indicates that play color was developed, 、 indicates that play color flickered, and X indicates that play color was not developed. [0040] [Table 1] average particle diameter CV aggregation rate concentration conductivity observation of the silica particles Silica electric solvent color play (μm) (%) (% ) ( volume%) (μS / cm) Example 1 0.06 6.5 1.6 0.86 4.8 Water ○ Example 2 0.10 4.9 2.0 0.91 5.7 Water ○ Example 3 0.10 4.9 2.0 6.82 63.5 Water ○ Example 4 0.08 6.0 1.8 0.86 3.2 Water ○ Example 5 0.11 4.2 0.2 0.23 1.2 Water ☆ Example 6 0.11 4.2 0.2 4.35 16.3 Water ☆ Example 7 0.11 4.2 0.2 4.65 14.2 Water ☆ Example 8 0.11 4.2 0.2 8.41 28.9 Water ☆ Example 9 0.11 4.2 0.2 0.73 1.0 Water / Et ☆ Example 10 0.11 4.2 0.2 1.31 1.1 Water / Et ☆ Example 11 0.11 4.2 0.2 3.77 3.1 Water / Et ☆ Example 12 0.11 4.2 0.2 0.55 0.9 Water / Eg ☆ Example 13 0.11 4.2 0.2 1.02 1.1 Water / Eg ☆ Example 14 0.08 6.0 1.8 0.73 1.0 Water / Et ☆ Example 15 0.20 5.0 2.0 0.73 1.0 Water / Et ☆ Example 16 0.08 6.0 1.8 1.74 1.2 Water / Et / Eg ☆ Example 17 0.11 4.2 0.2 6.50 15.6 Water ○ Example 18 0.11 4.2 0.2 17.00 71. 3 water ○ Example 19 0.16 10.0 3.0 0.06 0.6 water ☆ Comparative example 1 0.10 4.9 2.0 0.86 1 × 10 ³ water × Comparative example 2 0.04 5.6 2.0 0.73 1.8 water / Et × Comparative example 3 0.60 8.2 2.2 0.73 1.3 water / Et × Note: Et; ethanol, Eg; ethylene glycol The silica sol of the present invention is a silica sol exhibiting a completely new opal-like play color, and its glow is beautiful and specific. The opal-like play color is not only optically stable, but also the silica sol itself has high chemical stability. Therefore, this silica sol can be used as a cosmetic compound such as a lotion, an additive for paints, dyes and pigments, a display for a display device, an additive for various interior materials and exterior materials.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-208880 (JP, A) JP-A-63-285112 (JP, A) JP-A-58-41740 (JP, A) JP-A-2- 293314 (JP, A) JP-A-5-320022 (JP, A) Japanese Patent Publication No. 1-23411 (JP, B2) US Patent 4,451,388 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB) Name) C01B 33/00-39/54

Claims (1)

(57) [Claim 1] Silica particles having an average particle diameter in the range of 0.045 to 0.55 μm and a coefficient of variation of the particle diameter of 15% or less are water or a water-organic solvent. A silica sol exhibiting an opal-like free color, wherein the silica sol has an electric conductivity of 560 μS / cm or less.