JPH07324185A - Production of fine particle of benzotriazole derivative - Google Patents

Abstract

PURPOSE:To provide a method for efficiently producing fine particles of a benzotriazole deriv. with an average particle size of 0.01-0.7mum. CONSTITUTION:An emulsion of a benzotriazole deriv. is obtd. by adding the deriv. and a surfactant to a dispersion medium selected from among water, at least one alcohol, and a mixture of water with at least one alcohol, heating the medium together with the deriv. and the surfactant to the m. p. of the deriv. or above, and stirring them while keeping the temp. The resulting emulsion is cooled to the m.p. of the deriv. or below to precipitate the deriv. The alcohol used is selected from the group consisting of a 1-11C monool, a 2-4C diol, glycerin, and polyethylene glycol with a mol.wt. of 500 or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fine particles of a benzotriazole derivative used as an ultraviolet absorber having an average particle size of 0.7 μm or less.

[0002]

2. Description of the Related Art A benzotriazole derivative absorbs harmful ultraviolet rays of 290 to 400 nm due to its large ultraviolet absorption ability and can be converted into harmless heat energy or the like to be rendered harmless.
It is widely used to prevent quality deterioration and alteration of various products due to ultraviolet rays in the fields of textiles, paper, especially protective layers for thermal paper, coating films for coating plastic films, cosmetics and the like. Further, the benzotriazole derivative is also used as a rust preventive because it has excellent effects as a photographic antifoggant, a copper alloy, a silver corrosion inhibitor, and a discoloration inhibitor.

Since the benzotriazole derivative is melted by heat at a temperature higher than the melting point, in the case of application to plastic, it is added and mixed when the plastic melts in an extrusion molding machine, a kneading machine, etc., but is coated with an aqueous paint. As a component of the coating film, fine particles of a benzotriazole derivative are used when used, for example, in a surface layer of a plastic film or a light resistant layer of thermal paper, or when used in an emulsified dispersion state as in cosmetics. In the former case, the benzotriazole derivative is finely divided by heat melting to obtain a uniform dispersion, but when used in the form of fine particles as in the latter case, if the particle size of the fine particles is large, a uniform dispersion cannot be obtained and the surface area is Since it is small, there is a problem that the effect of absorbing ultraviolet rays is significantly impaired. Therefore, when using fine particles of a benzotriazole derivative, it is necessary to make the particle size small, uniform dispersibility and the surface area per unit weight large, and be careful to absorb ultraviolet rays efficiently. is there.

However, as a method for producing fine particles of a benzotriazole derivative, only an example in which it is produced by known dry pulverization or wet pulverization using a ball mill, an attritor, a sand mill or the like has hitherto been known. When producing fine particles having an average particle size of about 1 μm, wet pulverization is more efficient than dry pulverization, and a sand mill or the like is used as a pulverizing device, but the particle size of fine particles obtained by this method is Even if the crushing time is lengthened in preparation for the fact that the energy efficiency due to the above will be remarkably deteriorated, the obtained average particle size is about 0.8 μm at the lower limit. As described above, although it is strongly desired to obtain a benzotriazole derivative having a particle size smaller than the average particle size of the above-mentioned level, the benzotriazole derivative is a compound which is difficult to be finely divided, and therefore, existing mechanical properties are The crushing method applying the shearing force has a problem that it is not possible to manufacture particles having a particle size of the above level or less.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have diligently studied the miniaturization of a benzotriazole derivative in order to make up for the drawbacks in the prior art, and as a result, have noticed that the benzotriazole derivative melts due to heat, and the liquid dispersion medium The surfactant and the benzotriazole derivative are added to the mixture and heated to a temperature above the melting temperature (melting point) of the derivative to liquefy the derivative to form an emulsion, and then the temperature of the liquid dispersion medium is kept at room temperature. It was found that a very fine benzotriazole derivative can be obtained by lowering the benzotriazole derivative in the emulsion particles and precipitating the benzotriazole derivative in the emulsion particles, thereby completing the present invention.

The present invention has an average particle size of 0.01 to 0.7 μm.
An object of the present invention is to provide a production method capable of efficiently producing fine particles of a benzotriazole derivative in the range of m.

[0007]

The first of the present invention is water,
A surfactant and a benzotriazole derivative are added to a dispersion medium selected from a mixture of one or more alcohols and water and one or more alcohols, and the temperature of the dispersion medium is set to be equal to or higher than the melting point of the benzotriazole derivative. A method for producing fine particles of a benzotriazole derivative, which comprises heating and stirring at this temperature to form an emulsion of a benzotriazole derivative, and then lowering the temperature of the dispersion medium to the melting point or lower to precipitate the derivative. is there.

The second aspect of the present invention is that the alcohol of the dispersion medium has 1 to 11 carbon atoms and 1 hydroxyl group, 2 to 4 carbon atoms and 2 hydroxyl groups, glycerol and molecular weight are The method for producing fine particles of a benzotriazole derivative according to the first aspect of the present invention is characterized in that it is one kind or a mixture of one or more kinds selected from polyethylene glycol of 500 or less.

That is, according to the present invention, a benzotriazole derivative and a surfactant are added to a liquid dispersion medium which can maintain a liquid state at room temperature, and the benzotriazole derivative contained in the dispersion medium is heated to a temperature higher than its melting point. The benzotriazole derivative is then melted and stirred in this state to form an emulsion of the benzotriazole derivative, and then the temperature of the dispersion medium is lowered to the melting point or lower while maintaining this state with stirring, and thus the benzotriazole derivative is melted. Is precipitated in emulsion particles to obtain fine particles, which is a method for producing fine particles of a benzotriazole derivative.

The benzotriazole derivative used in the present invention is coarsely crushed and has a particle size of 7 to 15 μm, and there are many kinds of benzotriazole derivatives having a low melting point (80 ° C.) to a high melting point (200 ° C.). , For example, 2- (2′-hydroxyphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2-
(2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ',
5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-
5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-
Butylphenyl) -5-chlorobenzotriazole, 2
-(2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) -5-te
rt-Butylbenzotriazole, 2- (2'-hydroxy-3'-sec-butyl-5'-tert-butylphenyl) -5-tert-butylbenzotriazole, 2-
(2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-tert-amylbenzotriazole, 2-
[2'-hydroxy-3 '-(3 ", 4", 5 ", 6"
-Tetrahydrophthalimido-methyl) -5'-methylphenyl] benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- (2'-hydroxy-3'-sec-butyl-
5'-tert-butylphenyl) benzotriazole, 2
-(2'-hydroxy-3'-methyl-5'-sec-
Butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl)-
5-methoxybenzotriazole, 2- (2'-hydroxy-3'-tert-amyl-5'-phenoxyphenyl) -5-methylbenzotriazole, 2- (2'-hydroxy-5'-n-dodecylphenyl) Benzotriazole, 2- (2'-hydroxy-5'-sec-octyloxyphenyl) -5-phenylbenzotriazole, 2- (2'-hydroxy-3'-tert-amyl-
5′-phenylphenyl) -5-methoxybenzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole and the like can be mentioned. From the above, one kind or one kind or more is appropriately selected and used for fine particle formation, if necessary.

The dispersion medium used for the present invention is preferably a substance such as water or alcohol in which the benzotriazole derivative is difficult to dissolve from the viewpoint of production efficiency. Even if a dispersion medium in which the benzotriazole derivative is dissolved is used, it is possible to obtain fine particles without impairing the production efficiency by first saturating the dispersion medium and repeatedly circulating it. As another property of the dispersion medium, when the melting point of the dispersion medium is higher than the melting point of the derivative, the dispersion medium solidifies and precipitates during the operation of lowering the temperature after raising the temperature in the production process of fine particles. Since there arises a problem that the desired fine particles of the benzotriazole derivative cannot be taken out, it is preferable to use a dispersion medium that can maintain a liquid as the melting point of the dispersion medium when performing solid-liquid separation. However, in the present invention, from the viewpoint of thermal efficiency, it is preferable that after the above-mentioned derivative is deposited at a temperature below the melting point and the dispersion medium and the solid fine particles are separated, the temperature of the dispersion medium is not lowered as much as possible and the derivative is circulated and used again.

As the dispersion medium satisfying the above requirements, specifically, water, at least one alcohol, and a mixed liquid of water and at least one alcohol are preferably used as the dispersion medium for the present invention. . In addition, alcohols that can be used for the present invention include alcohols having 1 to 11 carbon atoms and one hydroxyl group, and alcohols having 2 to 4 carbon atoms and 2 hydroxyl groups.
Specific examples thereof include alcohol, glycerol, and polyethylene glycol having a molecular weight of 500 or less, and one or more alcohols can be used by appropriately selecting and combining them.

In the present invention, the surfactant and the solid benzotriazole derivative are added to the liquid dispersion medium, and the mixture is heated to a temperature not lower than the melting point of the derivative while stirring and dissolved to form an emulsion of the derivative. In this case, the particle size of the derivative before dissolution is not particularly limited. When water, a mixture of water and alcohol, or one or more alcohols is used as the dispersion medium having a melting point of less than 100 ° C. of the above derivative, a reaction vessel having a cooling device at the top and a high-speed stirring device is used. The evaporated liquid dispersion can be stirred under atmospheric pressure while being cooled and refluxed to form an emulsion. However, when the melting point of the derivative is higher than 100 ° C., a known air-cooled cooling method is used. A mixer equipped with a vessel or a closed type mixer with a high-speed stirrer or a homogenizer is preferably used.

In the present invention, the amount of the benzotriazole derivative added to the dispersion medium is 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less, based on the weight of the dispersion medium. When the amount of the derivative added exceeds 20% by weight, the melt of the benzotriazole derivative in the dispersion medium is not sufficiently dispersed and emulsified, and the particle size of the derivative fine particles obtained is 0.7.
It is not suitable because it becomes larger than μm. The addition amount is
When the particle size of fine particles of the benzotriazole derivative obtained is influenced and extremely small fine particles, for example, having a particle size of 0.1 μm or less are to be obtained, the addition amount is preferably 5% by weight or less.

Surfactants usable in the present invention include:
Known nonionic surfactants, anionic surfactants,
Sulfon group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, carboxymethylcellulose, and hydroxy, which are cationic surfactants and amphoteric surfactants, and also have protective colloid action in addition to surfactant properties. Propylmethyl cellulose and the like can be mentioned, and one or more of them can be used by appropriately selecting from these.

In the present invention, it is important to select a surfactant which significantly affects the formation of an emulsion of a benzotriazole derivative. When the dispersion medium used in the present invention is used in combination with a surfactant, the emulsion of the benzotriazole derivative tends to have a smaller average particle size when the interfacial tension is smaller. Therefore, since this interfacial tension changes depending on the kind of the surfactant, the composition of the dispersion medium and the temperature, the particle size of the obtained benzotriazole derivative fine particles can be appropriately adjusted by controlling these conditions.

For example, water is used as a dispersion medium, potassium oleate is added as a surfactant in an amount of 0.1 mol per 1 kg of the dispersion medium, and 2- (2'-hydroxy-3 ', 5) is further added as a benzotriazole derivative. '-Di-tert
-Amylphenyl) benzotriazole (trade name: Tinuvin 328, melting point: 80 ° C, manufactured by Ciba Geigy) was added in an amount of 2% by weight to the dispersion medium, and when the mixture was heated to 90 ° C and melted, a dispersion medium mixture was obtained. The interfacial tension between the benzotriazole derivative (Tinuvin 328) is 1.2 dyne.
/ Cm, and after the stirring treatment, the melted mixture was cooled to 30 ° C. to precipitate the benzotriazole derivative, and the average particle size of the obtained fine particles was 0.6 μm, while the dispersion medium was treated with water. From 20 to 20% by weight in ethanol and the other conditions were exactly the same, the interfacial tension was 0.2 dyne / cm, and the average particle size of the resulting fine particles was extremely small, such as 0.03 μm. It was

On the other hand, when the interfacial tension exceeds 1.5 dyne / cm and becomes large, the stability of the emulsion microdroplets decreases, and coalescence of the microdroplets occurs in a short time depending on the conditions, and the emulsion droplets May be larger,
The interfacial tension between the liquid mixture of the dispersion medium and the surfactant and the molten benzotriazole derivative needs to be as low as possible. The interfacial tension for the present invention is 1.
It is less than 5 dyne / cm, preferably 1 dyne / cm or less. The interfacial tension is measured by a surface tensiometer (model: Fa
ce, CBVP-A3, manufactured by Kyowa Interface Science Co., Ltd.).

As described above, in the present invention, the particle size of the derivative obtained by controlling the interfacial tension when the surfactant and the benzotriazole derivative are added to the dispersion medium is in the range of 0.03 to 0.7 μm. Can be easily obtained with. The benzotriazole fine particles in the above range thus produced are treated with a suspension having a solid content concentration of 50% by weight or less without being dried after washing if necessary, and further diluted as desired. Used.

[0020]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. Further, in the examples and comparative examples,% means% by weight.

Example 1 300 ml of water (distilled water) was used as a dispersion medium, and anionic surfactant potassium oleate (reagent, manufactured by Kanto Chemical Co., Inc.) as a surfactant was added thereto in an amount of 0. A container equipped with a stirrer (model: Ajihomomixer 2M
Type 03, manufactured by Tokushu Kika Kogyo Co., Ltd., and indirectly heated by an electric heating method. The evaporated medium of the dispersion medium is cooled and refluxed, and when the temperature of the dispersion medium reaches 90 ° C., a benzotriazole derivative is obtained. -(2'-hydroxy-
5 g of 3 ′, 5′-di-tert-amylphenyl) benzotriazole (trade name: Tinuvin 328, melting point: 80 ° C., average particle size 9.2 μm, manufactured by Ciba Geigy) (1.7 per weight of dispersion medium). %), And when the derivative was melted at the temperature, stirring was carried out at 8500 rpm for 60 minutes, and then the temperature was lowered to 30 ° C. while continuing stirring for 15 minutes to precipitate fine particles of the derivative. Dispersion medium mixture and benzotriazole derivative (Tinuvin 32
8) the interfacial tension at a temperature of 90 ° C is 1.2 dy
It was ne / cm. The obtained fine particles were treated with a pore size of 0.
Filter using a 025 μm membrane filter,
The fine particles are resuspended in distilled water, and the particle size of the fine particles is measured by using the liquid, using a laser type particle size meter (model: LPA-310).
0, manufactured by Otsuka Electronics Co., Ltd.). The average particle size of the fine particles was 0.60 μm.

Example 2 300 ml of an aqueous solution containing 20% by weight of ethanol was used as the dispersion medium, and the temperature of the dispersion medium was 8
When the temperature reached 5 ° C., 10 g (3.3% based on the weight of the dispersion medium) of tinuvin 328 (manufactured by Ciba Geigy) was added as a benzotriazole derivative, and the same procedure as in Example 1 was performed except that melting was performed at this temperature. Fine particles of the derivative were produced and the particle size was measured. Temperature between Dispersion Medium Mixture and Benzotriazole Derivative (Tinuvin 328) 85
The interfacial tension at 0 ° C. was 0.2 dyne / cm, and the average particle size of the fine particles was 0.03 μm.

Example 3 1500 ml of water (distilled water) as a dispersion medium was added to a nonionic surfactant (trade name: Emulgen 12) as a surfactant.
3P, manufactured by Kao Co., Ltd.) was added in an amount of 0.1 mol per 1 kg by weight of the dispersion medium, and 2- (2′-hydroxy-3 ′, 5′-tert-butylphenyl) benzotriazole (trade name: Sumisorb 320) was added as a benzotriazole derivative. , Melting point 152
℃, average particle size 9.7μm, Sumitomo Chemical Co., Ltd.) 250g
(16.7% based on the weight of the dispersion medium) was added, and the mixture was added to a pressure reactor equipped with a stirrer (model: Homomixer MARK).
10 type, manufactured by Tokushu Kika Kogyo Co., Ltd., temperature 160 ℃,
Stirring is performed at 8500 rpm for 60 minutes, and then 1
Continue stirring for 5 minutes while lowering the temperature to 30 ° C,
Fine particles of the derivative were deposited. The interfacial tension between the dispersion medium mixture and the benzotriazole derivative (Sumisorb 320) at a temperature of 160 ° C. could not be measured. The average particle size of the obtained fine particles was 0.62 μm as measured by the same method as in Example 1.

Example 4 As a dispersant, ethylene glycol (boiling point: 197 ° C.) 30
0 g of nonionic surfactant (reagent:
Tween 20, manufactured by Wako Pure Chemical Industries, Ltd.) as a dispersion medium 1 kg
Addition of 0.1 mol per weight, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole as a benzotriazole derivative (trade name: Tinuvin P, melting point 130 ° C, average particle size 8.5 μm, Ciba. 10 g (manufactured by Geigy) (3.3% based on the weight of the dispersion medium),
Fine particles of the above derivative were produced in the same manner as in Example 1 except that stirring was performed at 150 ° C., and that water was not passed through the condenser at the top of the container, and the particle size thereof was measured.
The interfacial tension between the dispersion medium mixture and the benzotriazole derivative (Tinuvin P) at a temperature of 150 ° C. is 0.2 d.
The average particle size of the fine particles was 0.09 μm in yne / cm.

Example 5 As a dispersion medium, ethylene glycol (boiling point 197 ° C.) 3
3 g of acetoacetyl group-modified polyvinyl alcohol (trade name: Gocefimer Z200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added to 00 g, and the benzotriazole derivative (Tinuvin P) was added per 300 g of the dispersion medium to 21 g.
Fine particles of the benzotriazole derivative were produced in the same manner as in Example 4 except that g (7.0% based on the weight of the dispersion medium) was added, and the particle size was measured. Temperature between the dispersion medium mixture and the benzotriazole derivative (Tinuvin P) 1
The interfacial tension at 50 ° C. was 0.4 dyne / cm, and the average particle size of the fine particles was 0.17 μm.

Example 6 Fine particles of a benzotriazole derivative were produced in the same manner as in Example 5 except that 300 g of polyethylene glycol having a molecular weight of 400 (melting point: 4-8 ° C., manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersion medium. The particle size was measured. The interfacial tension between the dispersion medium mixture and the benzotriazole derivative (Tinuvin P) at a temperature of 150 ° C. is 0.6 dyne /
In cm, the average particle size of the microparticles was 0.25 μm.

Comparative Example Tinuvin P (melting point: 13 as a benzotriazole derivative
0 ° C., average particle size 8.5 μm, Ciba-Gayky) 35
g, 0.5 g of sulfonic acid-modified polyvinyl alcohol, and 85 g of water, and an average particle size of 0.6 as a medium
190 g of glass beads of mm are put in a sand grinder (six-cylinder type, manufactured by AIMEX Co., Ltd.) having a treatment capacity of 300 ml, and the temperature of the circulating water for cooling is adjusted to be a batch type at a crushing temperature of 20 ° C. and a stirring machine rotation speed of 2000 rpm. Microparticles of the above derivative, which were crushed and treated for treatment times of 3, 24 and 72 hours, were prepared.
The average particle size was measured in the same manner as. The average particle size was 1.82 μm for the one treated for 3 hours and 1.2 μm for the one treated for 24 hours.
The value after the treatment for 20 μm for 72 hours was 0.79 μm.

The results obtained in the examples and comparative examples are shown in Table 1.

[0029]

[Table 1]

As can be seen from the table, the average particle size of the benzotriazole derivative obtained according to the present invention is 0.03 to
It is in the range of 0.63 μm and is extremely fine particles. On the other hand, in the conventional pulverization method, it is difficult to obtain the particles having the particle size according to the present invention even over a long period of time, and when the benzotriazole derivative obtained according to the present invention is used as the ultraviolet absorber, uniform dispersion is possible, Since the surface area is extremely large, the ability to absorb ultraviolet rays (light resistance) can be significantly improved.

[0031]

As described in detail above, the present invention has an effect of providing a method capable of producing benzotriazole derivative fine particles having a particle size significantly smaller than the average particle diameter by a conventional mechanical grinding method.

Claims (2)

[Claims] 1. A surfactant and a benzotriazole derivative are added to a dispersion medium selected from water, one or more alcohols, and a mixture of water and one or more alcohols, and the temperature of the dispersion medium is increased. Is heated above the melting point of the benzotriazole derivative and stirred at that temperature to form an emulsion of the benzotriazole derivative, and then the temperature of the dispersion medium is lowered below the melting point to precipitate the derivative. Method for producing fine particles of a benzotriazole derivative. 2. The alcohol of the dispersion medium has 1 to 1 carbon atoms.
One having one hydroxyl group, one having 2 to 4 carbon atoms and two hydroxyl groups, glycerol, molecular weight 500
The method for producing benzotriazole derivative fine particles according to claim 1, which is one kind or a mixture of one or more kinds selected from the following polyethylene glycols.