JPH013020A - Titania sol and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a titania sol that maintains a stable dispersion state at a neutral pH range and a method for producing the same. The titania sol of the present invention having such characteristics can be adjusted to any pH range, and the titania fine particles maintain a stable state in each pH range, making it suitable for various uses. For example, it is useful as a raw material for cosmetics, food packaging materials, etc. that utilize its ultraviolet blocking effect.

[Conventional technology]

Generally, fine titania powder, most of which has a particle size of 0.1 μm or less, transmits visible light when incorporated into a resin film or molded product, while blocking ultraviolet rays and discoloring due to ultraviolet rays. Because it protects substances that deteriorate, it is used in plastic packaging materials for foods and medicines, plastic covering materials for greenhouse farming and horticulture, and cosmetics. Such fine titania powder is produced by heating and hydrolyzing an aqueous titanium sulfate solution, neutralizing and washing the precipitated hydrated titanium oxide aggregates, and peptizing the aggregates by adding an acid such as hydrochloric acid or nitric acid.
It is usually obtained by producing a titania sol of 3 or less, and then neutralizing this sol, followed by filtration, washing, drying, and pulverization.

[Problem that the invention seeks to solve]

Generally, the dispersion of titania sol is stabilized by acidic substances such as hydrochloric acid and nitric acid as described above, but at pH 3.
Since it exhibits the following acidity, it is not suitable for a wide range of uses as it is. Neutralization-washing, ion exchange, ultrafiltration, etc. may be performed to remove acidic substances and make a neutral titania sol, but such methods impair the physical properties of titania sol, such as its dispersibility. However, it is difficult to obtain a neutral titania sol that exhibits stable dispersibility. Therefore,
Generally, acidic titania sol must be neutralized, washed, dried, and pulverized to be used as a dry powder, but in this case, it is not possible to reproduce the dispersion state like that of a sol, and the characteristics of fine particles cannot be fully brought out. This is the current situation.

[Means for Solving the Problems] The present inventors have conducted various studies in order to utilize the acidic chiknia sol for various purposes while maintaining a good dispersion state. As a result (a) When the acidic substances in the acidic titania sol are removed by means such as ion-exchange resin, ion-exchange membrane, or electrodialysis, gelation occurs immediately and the titania fine particles aggregate, but after several hours of stirring, they unexpectedly regenerate. (b) If a water-soluble organic compound such as polyvinyl alcohol or glycerin is mixed before or after removing the acidic substance, a more uniformly dispersed titania sol in a stable state can be obtained; (viii) This titania sol is It shows pi in the neutral range, and its stable state is maintained even if the pH is changed over a wide range by adding acidic or alkaline substances. It was found that it can be easily formed into a coating film by mixing with a synthetic resin, and that the coating film has ultraviolet absorbing ability. The present invention is based on these findings.

The first invention of the present application is a titania sol characterized by being an aqueous dispersion in which titania fine particles are dispersed and exhibits pl+ in the neutral range. This is a method for producing titania sol, which is characterized by removing anions from acidic titania sol obtained by peptizing it with salt.

The titania sol of the present invention has titania fine particles dispersed therein.
It is an aqueous dispersion having a pH in the neutral range of pH 6 to 8. Further, the titania sol of the present invention may contain a dispersion stabilizer as necessary in order to stabilize the dispersion of the titania fine particles. The titania sol of the present invention has titania fine particles uniformly dispersed in water, and its pH can be adjusted arbitrarily, and the titania sol is diluted as necessary.
By kneading it with various resins, applying it, and drying it, a transparent coating film that maintains a highly dispersed state can be obtained, so it can be used, for example, as a UV-blocking resin composition applied to the surface of food packaging materials. Can be done. It can also be blended into cosmetic materials and used as UV-blocking cosmetics.

The titania fine particles that are a component of the titania sol of the present invention are
It means hydrous titanium oxide, and in the present invention, it includes amorphous ones such as metatitanic acid and orthotitanic acid, those having some rutile type or anatase type crystals, or mixtures thereof. For example, when titania sol is used as a raw material for an ultraviolet blocking resin composition, titania fine particles account for most of the titania sol (f#! 80% or more).
It is desirable that the size is within the range of 0°1 μm or less.

If the particle size becomes too large or the particles aggregate, the visible light scattering ability will increase and transparency will be impaired.

Dispersion stabilizers to be added as necessary include water-soluble organic compounds and inorganic surfactants. Specifically, water-soluble organic compounds include polyvinyl alcohol,
Water-soluble polymer compounds such as carboxymethyl cellulose and methyl cellulose, nonionic surfactants such as polyoxyethylene alkylphenyl ether compounds, polyoxyethylene alkyl ether compounds, and polyoxyethylene fatty acid ester compounds, aliphatic amine salts,
Cationic surfactants such as quaternary ammonium salts, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 2-methyl-2,4-
Examples include polyhydric alcohols such as penkdiol and glycerin. Examples of the inorganic surfactant include sodium birophosphate, sodium hexametaphosphate, and sodium silicate. In terms of dispersion stabilizing effect, water-soluble organic compounds are more desirable than inorganic surfactants. Water-soluble polymer compounds have various degrees of polymerization, but for example, in the case of polyvinyl alcohol, it is easier to obtain a titania sol with a higher concentration of riOz with a lower degree of polymerization than with a higher degree of polymerization, and therefore, with a degree of polymerization of 1900 It is better to use one with a polymerization degree of about 500 than one with a polymerization degree of 2100. It should be noted that when using monohydric alcohols such as methanol and ethanol, it is difficult to obtain a stable neutral sol in a region where the TiO□ concentration is high.

The concentration of titania fine particles in the titania sol is 1 to 1 as TiO□ from the viewpoint of forming a sol in a stable dispersion state.
40% by weight is appropriate. Also, the concentration of the dispersion stabilizer is 1
~99% by weight is suitable.

The titania sol of the present invention maintains a stable dispersion state in a neutral pH range, and can be adjusted to any desired ρ1. , an alkaline substance can be appropriately added, blended, or heated.Furthermore, resins, colorants, etc. may be blended as necessary.

The second invention of the present application provides one of the methods for producing titania sol.

In the wooden mold making method, first, hydrous titanium oxide is peptized with a monobasic acid or its salt to produce an acidic titania sol. Hydrous titanium oxide can be obtained, for example, by heating and hydrolyzing a titanium sulfate solution or a titanium tetrachloride solution, or by neutralizing it with an alkali. Hydrous titanium oxide obtained by heating and hydrolysis is usually neutralized with an alkaline substance such as aqueous ammonia, filtered, washed, and dehydrated to remove as much of the sulfuric acid groups remaining inside as possible. A monobasic acid such as hydrochloric acid, nitric acid, acetic acid, chloric acid, or chloroacetic acid is added to peptize the material. Alternatively, the above-mentioned neutralization-based desulfation treatment (for hydrous titanium oxide,
Peptization can also be carried out by adding a salt, such as barium chloride, which reacts with the sulfate radicals to form an insoluble sulfate salt and at the same time forms a monovalent acid. Chiknia sol produced by peptizing treatment contains -basic acid as a stabilizer,
Usually exhibits acidity of pl+3 or less.

Next, after removing the anions from the acidic titania sol, the acidic titania sol is stirred to obtain a titania sol. Anions can be easily removed using, for example, an anion exchange resin, an ion exchange membrane, electrodialysis, or the like. Although the titania fine particles in the sol tend to aggregate due to the removal of anions, they can be uniformly dispersed by continuing stirring.

In the method of the present invention, it is desirable to mix a dispersion stabilizer before or after the removal of the anions in order to further enhance the dispersion of the titania fine particles in the sol. In this case, the dispersion stabilizer is usually used at a concentration of 1 to 100% by weight with respect to the acidic titania sol having a TiO□ concentration of 1 to 40fffffi%, and the weight ratio with TiO□ is 0.05 to 10, preferably 0. It is appropriate to mix so that the value falls within the range of .1 to 5. Thereafter, it can be heated and concentrated if necessary. At the time of mixing, if the TiO□ concentration of the acidic chikunia sol exceeds the above range, it will be difficult to obtain a sol in a stable dispersed state, regardless of the concentration of the dispersion stabilizer, and should be avoided.

Anion removal using an anion exchange resin, an ion exchange membrane, electrodialysis, etc. can be carried out according to conventional methods. For example, as the anion exchange resin, those commercially available under -1G, such as Amberlite IRA400, Amberlite IRA410, and Amberlite IRA910, can be used.

Note that the amount added can be appropriately selected depending on the desired amount of anions to be removed.

It is also possible to increase the T i Ot Qa degree of the titania sol by simultaneously removing anions using an ion exchange resin or the like while mixing the acidic titania sol with the dispersion stabilizer.

In addition, in the present invention, when producing a rutile type titania sol in particular, hydrated titanium oxide obtained by neutralizing a titanium chloride aqueous solution such as a titanium tetrachloride aqueous solution while maintaining the pH at 7 or higher with an alkaline solution is added to an acidic solution. It is desirable to adopt a method in which an acidic rutile-type titania sol is obtained by heating in the sol, and then anions in the sol are removed. In this method as well, it is desirable to mix the dispersion stabilizer before or after removing the anions in the acidic sol from the viewpoint of forming a sol in a more stable dispersed state.

In the production method of the present invention, anions in the acidic titania sol are removed using an anion exchange resin 1, an ion exchange membrane, electrodialysis, etc., but if necessary, a dispersion stabilizer is added before or after the anion removal. May be mixed. By this method, acidic titania sol can be made into titania sol that exhibits stable dispersibility in the neutral pHeM range. Further, the pH of this product can be adjusted to be in the alkaline range or the pl+ in the acidic range by appropriately adding an alkaline substance such as ammonia water or an acidic substance such as an aqueous hydrochloric acid solution.

The titania sol of the present invention has titania fine particles that dissolve well in water. Because of this, it is easy to mix with cosmetic bases or other cosmetic ingredients, and it has a sufficient UV blocking effect with a smaller amount than conventional fine titania powder.
It has excellent transparency and is useful as a sunscreen cosmetic.

The amount of titania sol in the cosmetic is 0.1 to 10% by weight, preferably 1 to 5% by weight as Ti0z.

Cosmetics can be used in any form such as lotion, cream, paste, stick, or milky lotion.

〔Example〕

A. Preparation of acidic titania sol Ti
An aqueous slurry containing 30% by weight of O□ was prepared, and this slurry was neutralized to pH 7 with aqueous ammonia, and then filtered and washed to remove sulfate groups. The obtained dehydrated cake was deflocculated by adding 35% hydrochloric acid, and 11cj! A titania sol having a pH of 1.5 and containing 1.5% by weight was obtained.

B. Production of neutral titania sol (a) Acidic titania sol (Ti0230 weight%) obtained in the above section A 250mj? While stirring well, add a wet anion exchange resin (Amberlite IRA910,
About 1000 g (manufactured by Tokyo Organic Chemical Co., Ltd.) was quickly added thereto, and after stirring for about 4 hours, the on-exchange resin was removed by filtration to obtain a neutral titania sol (20% by weight of TiO□) with a pl+7.8.

C. Production of neutral titania sol (b) 250 mj2 of the acidic titania sol obtained in the above section A was added with 250 m# of commercially available glycerin, and then about 1000 g of the same anion exchange resin as above was added with stirring.

After stirring thoroughly, the ion exchange resin is removed by filtration.
A neutral titania sol (Ti02 12% by weight) of H7,2 was obtained.

D Heating concentration of neutral titania sol The neutral titania sol (b) obtained in the above item 0 was heated at 100°C.
The mixture was heated and concentrated to obtain a stable sol containing 25% by weight of titania as TiO□.

E. Production of neutral titania sol (c) In the same manner as in item 0 above, except that 250 ml of ethylene glycol was added instead of glycerin, the pH-? , 2 neutral titania sol (TiO□12x4%)
I got it.

F Production of neutral titania sol (d) In the above item 0, a polyvinyl alcohol solution with a degree of polymerization of 500 (PVA solid content 50 g/1) was used instead of glycerin.
Neutral titania sol (TiO
z2.4% by weight) was obtained.

G. Production of neutral titania sol (N) Approximately 1000 g of the anion exchange resin was added to 250 mβ of acidic titania sol (TiOz 30%), stirred well, and the vaginal ion exchange resin was filtered out, followed by 250 ml of glycerin. was added to obtain a stable neutral sol (TiOz 12% by weight) with a pl+7.8.

I (Test Example 1 TiO The transmittance was measured using a self-recording spectrophotometer (Kyoho UV-240 model, manufactured by Shimadzu Corporation) and was 98% and 2%, respectively.
Met.

■ Test Example 2 Using the neutral titania sol (B) obtained in item 0 above, mix it with the following components (2) to (4), and add (5
) and (6) are added and dispersed uniformly to make cosmetics (
Manufactured a sunscreen lotion.

Ingredients Mixing ratio (wt%) (1) Neutral chikunia sol (TiO712 wt%) 80 (
2+ 1, 3-butylene glycol 3
(3) Ethanol 12 (
4) Appropriate amount of fragrance (5)
Silicic anhydride (6) Kaolin 2
The coating film of the sunscreen lotion thus obtained was 12
．． It was coated onto a triacetate film using a 0.5 mi+ doctor blade so that the thickness was 7 μm.

The transmittance of the obtained film was measured using a self-recording spectrophotometer (quality UV
240, manufactured by Shimadzu Corporation), and the results shown in the table below (Example) were obtained.

(Note) In the comparative example in the table, the neutral titania sol of the above example was replaced with 12% by weight of finely powdered titanium dioxide with an average particle size of 0.03 to 0.05 μm, 58% by weight of purified water, and 30% by weight of glycerin. After mixing this mixture with components (2) to (4) of Test Example 2 in the same proportions,
A sunscreen lotion is obtained by mixing components (5) and (6) in the same proportion.

〔Effect of the invention〕

Conventional titania sol usually exhibits acidity of pl (3 or less), but the one of the present invention maintains a stable dispersion state in the neutral pH range and has a wide range of pi+
can be adjusted, and is expected to be used in a wide range of applications without being limited.

Further, the titania sol of the present invention does not gel even when used under severe conditions and maintains a stable dispersion state. Furthermore, the titania sol of the present invention is stable against heat treatment, and can be concentrated to a desired TiO□ concentration by heating as appropriate depending on the purpose and use.

Claims (1)

[Claims] 1. A titania sol characterized by being an aqueous dispersion having a pH in the neutral range, in which titania fine particles are dispersed. 2. The titania sol according to claim 1, which contains at least one dispersion stabilizer selected from water-soluble organic compounds and inorganic surfactants. 3. A method for producing titania sol, which comprises removing anions from an acidic titania sol obtained by peptizing hydrous titanium oxide with a monobasic acid or a salt thereof. 4. Claims characterized in that a dispersion stabilizer is mixed into the acidic titania sol obtained by peptizing hydrous titanium oxide with a monobasic acid or its salt before or after removing anions from the sol. The manufacturing method according to item 3.