JPH0625121B2 - Method for producing fine particles of 2-mercaptopyridine-N-oxide polyvalent metal salt - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a 2-mercaptopyridine-N-oxide polyvalent metal salt, and in particular, it is used by being added to a liquid as an antibacterial agent. Fine particle size 2
It relates to a method for producing a mercaptopyridine-N-oxide polyvalent metal salt.

[Conventional technology]

2-Mercaptopyridine-N-oxide polyvalent metal salt (hereinafter abbreviated as "Me-pt") has an antibacterial action and is highly effective for sterilizing and cleaning the skin due to its high safety to the human body, especially shampoo. Widely applied as a shampoo to prevent dandruff by adding it to the base. The dandruff not only looks dirty on the hair, but it is also unpleasant with itchiness, but the occurrence of dandruff is directly or indirectly related to the reproduction of microorganisms on the scalp. Me-pt is poorly soluble in water and is added to the shampoo in the form of a suspended solid, but the good antidandruff effect is that the particles remaining on the scalp and hair after shampoo are persistently absorbed. It is believed to have an antibacterial effect. However, since it must be used in suspension, the liquid composition such as shampoo to which it is added loses transparency and becomes turbid in appearance, and in order to prevent sedimentation, for example, JP-B-49-49117. When a thickening polymer such as a cross-linked polyacrylic acid salt is added to the medium so as to provide a medium with a pseudoplastic viscosity behavior having a yield value as disclosed in Japanese Patent Laid-Open Publication No. JP-A-2003-264, a technique for stabilizing dispersion is always required.

One way to improve the properties of these Me-pts is Me-pt.
It is to make pt small particles. As this method, the present inventors have previously reacted the 2-mercaptopyridine-N-oxide with a water-soluble polyvalent metal salt in the presence of a water-soluble compound having a basic nitrogen in the molecule, and Me-pt A method for producing fine particles (JP-A-60-16973) has been proposed.

[Problems to be solved by the invention]

However, since the water-soluble compound having a basic nitrogen used in the reaction remains in the Me-pt fine particles obtained by the above method, there may be a problem in preparing various compositions using the same. I knew it. For example, when preparing a composition with an anionic polymer that is usually blended in shampoos, rinses, etc., this is incompatible with a water-soluble compound having a basic nitrogen, and a practical composition may not be prepared. Therefore, it has been desired to develop a new method for producing Me-pt microparticles that does not cause inconvenience when various compositions are used.

[Means for solving problems]

In view of the above situation, as a result of earnest research by the present inventor, it was found that the object can be achieved by reacting 2-mercaptopyridine-N-oxide with a polyvalent metal salt in the presence of a specific neutral compound. The present invention has been completed.

That is, the present invention is characterized in that a monovalent water-soluble salt of 2-mercaptopyridine-N-oxide and a water-soluble polyvalent metal salt are reacted in the presence of polyvinyl alcohol.
A method for producing Me-pt fine particles is provided.

The method for producing the fine particle antibacterial agent, Me-pt, of the present invention, for example, taking a divalent metal as the polyvalent metal salt, is represented by the following formula.

(In the formula, Me represents a divalent metal atom.) The 2-mercaptopyridine-N-oxide ion is supplied as a monovalent salt of 2-mercaptopyridine-N-oxide such as sodium, potassium, ammonium and ethanolamine. Of these, sodium salts are preferred.

The polyvalent metal ion is supplied from its water-soluble salt.

As the water-soluble polyvalent metal salt used in the present invention, calcium, magnesium, barium, styrontium, zinc,
Water-soluble salts of cadmium, tin, zirconium, etc., having a solubility of 0.01 g or more in 100 g of water are preferable, and zinc salt is most preferable. The anion part of these water-soluble polyvalent metal salts is preferably one derived from halogen (among others chlorine and bromine), sulfuric acid, carbonic acid, nitric acid, acetic acid and the like. The most preferable zinc salt is not particularly limited as long as it is a salt of divalent zinc, and examples thereof include zinc salts of inorganic acids or organic acids, and specific examples thereof include zinc chloride, zinc bromide, zinc sulfate and the like. preferable. Further, these salts may be in the form of either an anhydrate or a hydrate.

The polyvinyl alcohol used in the present invention can be selected from a wide range of molecular weight and saponification degree.

The polyvalent metal ion and 2-mercaptopyridine-N-oxide ion may each be present in stoichiometrically necessary amounts.

In carrying out the reaction, it is preferable to charge the whole amount of polyvinyl alcohol in the reaction vessel before the reaction by the other two components among the above three components, but the mixing order of the other two components is not particularly limited. Not done. 2 for polyvinyl alcohol
-Mercaptopyridine-N-oxide may be dissolved in a monovalent salt aqueous solution and / or a polyvalent metal salt aqueous solution, or may be previously charged as an aqueous solution into a reaction tank. In particular, 0.08 to 6% by weight (hereinafter referred to as%) of 2-mercaptopyridine-N
A monovalent oxide salt, a polyvalent metal salt equivalent thereto, and 0.
It is preferable to mix them so as to obtain a polyvinyl alcohol aqueous solution of 05 to 10%. The reaction is preferably carried out by mixing as rapidly as possible. The reaction temperature is preferably room temperature or lower. In particular, Me-pt fine particles produced at a reaction temperature of 0 to 5 ° C.
When it was crushed with a machine or the like, it could be easily made finer than that produced under other reaction temperature conditions.

[Action and effect]

Since Me-pt obtained by the method of the present invention is fine particles, it has excellent dispersion stability as compared with conventional Me-pt. Therefore, when this is added to the composition, the transparency and dispersed state of the composition are improved, and the dispersion and transparency of the shampoo, rinse, etc. are improved. Also, not only these,
Polyvinyl alcohol, which may remain in the Me-pt microparticles, is a neutral compound and is inert to other components added to the composition, and therefore, for example, a hair styling agent, a hair styling agent, a wave set agent. It enables a wide range of applications in various hair cosmetics and skin cosmetics such as hair lotion and hair cream, as well as aqueous latex emulsions and aqueous inks.

〔Example〕

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 An aqueous solution containing 0.29 g of zinc sulfate heptahydrate and 0.1 g of polyvinyl alcohol (polymerization degree 2000, manufactured by Wako Pure Chemical Industries) (p
(Adjusted to H6) 99.3g was added to the reaction solution, and it was added to this at room temperature 2
-Sodium salt of mercaptopyridine-N-oxide 4
0.75 g of 0% aqueous solution is added for 1 second. The system becomes a white emulsion. The precipitated particles of the zinc salt of 2-mercaptopyridine-N-oxide (hereinafter abbreviated as "Zpt") were collected by centrifugation. The average particle size was 0.32 micron (centrifugal sedimentation method).

Example 2 A particulate Zpt was prepared under the same reaction conditions as in Example 1 except that the temperature of the reaction system was changed from room temperature to 2 ° C. The average particle size was 0.32 micron (centrifugal sedimentation method).

Comparative Example 0.29 g of zinc sulfate heptahydrate and 2-mercaptopyridine-N under the same conditions as in Example 1 above without using polyvinyl alcohol.
-When the sodium oxide salt was reacted, large rod-shaped particles were deposited. A similar reaction was carried out using polyethylene glycol or a condensate of an aliphatic alcohol and ethylene oxide instead of polyvinyl alcohol, but the particulate Zpt obtained in the examples could not be obtained.

Test Example 23 g of each Zpt powder produced by the method of Example 1 (reaction at room temperature) and Example 2 (reaction at 2 ° C.) was separately put into a sand grinder (made by Igarashi Machinery Co., Ltd.) having an internal volume of 400 m. , 63 g of water and 187 g of glass beads with a diameter of 0.1 to 0.2 mm are added, and the disk is driven for 5 hours at a peripheral speed of 6 m.
It was rotated at 1 / sec. The temperature in the sand grinder is 20
It was ~ 25 ° C. When the operation was stopped and the contents were filtered under pressure, about 40 g of pulverized Zpt dispersion liquid was obtained. Also,
It was washed twice with glass beads and 70 g of water, and the washing liquid was also mixed with the above-mentioned dispersion liquid to prepare Zp contained in this liquid.
The particle size distribution of t particles was investigated. As a result, when the Zpt particles of Example 1 were used as the raw material, the Zpt dispersion obtained had a concentration of 0.1
Sub-micron particles accounted for about 55% of the total. Also,
When the Zpt particles of Example 2 were used as the raw material, particles of 0.1 micron or less accounted for about 75% of the whole.

Claims (3)

[Claims] 1. A 2-mercaptopyridine-N-oxide polymer, which comprises reacting a monovalent water-soluble salt of 2-mercaptopyridine-N-oxide with a water-soluble polyvalent metal salt in the presence of polyvinyl alcohol. Method for producing fine particles of valent metal salt. 2. The method for producing 2-mercaptopyridine-N-oxide polyvalent metal salt fine particles according to claim 1, wherein the reaction temperature is room temperature or lower. 3. The method for producing 2-mercaptopyridine-N-oxide polyvalent metal salt fine particles according to claim 1, wherein the reaction temperature is 0 to 5 ° C.