JP7274097B2 - Zinc carboxylate composition and zinc carboxylate solution containing same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a carboxylic acid metal salt that can reduce the viscosity of a zinc carboxylate solution and reduce viscosity changes. Zinc carboxylates can be used for applications such as thickening agents for grease, additives for lubricating oils, and raw materials for precursors of semiconductor quantum dots. The zinc carboxylate can be used by dissolving it in a solvent or oil during the manufacturing process.

Carboxylic acid metal salts are conventionally used as thickeners for grease, additives for lubricating oils, raw materials for precursors of semiconductor quantum dots, and the like.

For example, there is a description that zinc acetate and oleic acid are reacted in 1-octadecene at 120° C. for 1 hour to obtain a solution of zinc oleate in the production of semiconductor precursors (Patent Document 1).

As described above, zinc carboxylates are dissolved in solvents and oils and used in the manufacturing processes of thickeners for grease, additives for lubricating oils, raw materials for precursors of semiconductor quantum dots, and the like.

JP 2011-194562 A

A zinc carboxylate has a considerably high viscosity when melted and is poor in handleability. Therefore, it may be dissolved in a large amount of solvent or oil and diluted to improve handleability. However, even in such a diluted solution, there are cases where the viscosity is not sufficiently reduced, and cases where the thixotropic property worsens as the solution is diluted.

The zinc oleate solution used in the production of the quantum dot precursor described in Patent Document 1 sometimes suffers from a change in viscosity due to energy such as rotation, resulting in poor thixotropic properties, making precise control during production difficult in some cases.

An object of the present invention is to sufficiently reduce the viscosity of the zinc carboxylate solution and reduce the viscosity change even when the zinc carboxylate is dissolved in a large amount of solvent and used from the viewpoint of handling.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that zinc carboxylate can be dissolved in a large amount of solvent when the carboxylic acid constituting the zinc carboxylate has a specific composition. The inventors have found that the viscosity of the salt solution can be sufficiently lowered to reduce the change in viscosity, leading to the completion of the present invention.

That is, the present invention relates to (1) and (2).
(1) A zinc carboxylate composition comprising the following zinc salt of component (A) and zinc salt of component (B),
The ratio of the component (A) in the carboxylic acid constituting the zinc carboxylate composition is 90.0 to 99.9% by mass, and the ratio of the component (B) is 0.1 to 10.0% by mass. A zinc carboxylate composition characterized by:

(A) linear saturated monocarboxylic acid having 8 carbon atoms (B) linear saturated monocarboxylic acid having 6 carbon atoms (2) containing the carboxylic acid zinc salt composition of (1) and a solvent, A zinc carboxylate solution, characterized in that the content of the zinc acid salt composition is 0.01 to 30% by mass.

According to the present invention, when a zinc carboxylate such as a desiccant for paint, an additive for lubricating oil, or a precursor material for quantum dots is used by dissolving it in a large amount of solvent, the zinc carboxylate solution of the present invention can be used. Viscosity can be sufficiently lowered to reduce viscosity change.

(Carboxylic acid zinc salt)
The composition of the carboxylic acid, which is the starting material for the carboxylic acid alkali metal salt, includes the aforementioned component (A) and component (B).

The ratio of component (A) is 90.0 to 99.9% by mass when the total amount of carboxylic acids constituting the zinc carboxylate in the composition is 100% by mass. This results in low viscosity and improved thixotropy. From this point of view, the proportion of component (A) is preferably 92.5% by mass or more, more preferably 95.0% by mass or more, and particularly preferably 98.0% by mass or more.

The amount of component (B) is 0.1 to 10.0% by mass when the total amount of carboxylic acids constituting the zinc carboxylate in the composition is 100% by mass. As a result, the thixotropic property is improved at a low viscosity, but when the component (B) exceeds 10.0% by mass, the viscosity change becomes large and the thixotropic property is deteriorated. From this point of view, the amount of component (B) is preferably 7.5% by mass or less, more preferably 5.0% by mass or more, and particularly preferably 2.0% by mass or less. Moreover, the amount of component (B) is particularly preferably 0.5% by mass or more.

(Method for producing zinc carboxylate)
The main methods for producing metal carboxylates are the direct method and the metathesis method. The direct method is a method of obtaining a carboxylic acid metal salt by direct reaction of a molten carboxylic acid and a metal oxide or metal hydroxide. On the other hand, the metathesis method is a method of obtaining a metal carboxylate by reacting an aqueous solution of an alkali metal carboxylate with an inorganic metal salt.

The direct method has advantages in terms of equipment such as simple process and small scale of equipment, but on the other hand, it has the following problems.
(a) Completion of the reaction is poor, and a large amount of unreacted carboxylic acid and the metal oxide or metal hydroxide used as starting materials remain in the carboxylic acid metal salt. (b) The hue of the metal carboxylate is poor due to the reaction at high temperature.
(c) Since the reactivity is poor, a basic carboxylic acid metal salt (monosalt) is present in the resulting carboxylic acid metal salt, because a metal oxide or a metal hydroxide is reacted with a conventional carboxylic acid in an equimolar amount or more. remains, the melting point increases and the solubility decreases.

On the other hand, the metathesis method, which is completely opposite to the above direct method, has quality advantages such as less content of unreacted carboxylic acid, raw material metal compounds, dissimilar metals, etc., good color, and fine powder. However, on the other hand, there are also the following problems.
(a) Huge manufacturing facilities are required.
(b) The dispersibility of the reaction slurry in water is unstable, resulting in poor workability. (c) It is difficult to reduce the water content of the product.

The zinc carboxylate of the present invention may be produced by either the direct method or the metathesis method, but the zinc carboxylate by the metathesis method is more preferable from the viewpoint of color resistance and dissolution stability in a solvent. .

The zinc carboxylate of the present invention is metal carboxylate particles obtained by reacting an alkali metal carboxylate and a divalent zinc salt, for example, in an aqueous solution. The divalent zinc salt is specifically a salt of divalent zinc metal and an inorganic acid or an organic acid. As the divalent inorganic zinc salt, zinc sulfate, zinc chloride and zinc nitrate are preferred. Among them, zinc sulfate and zinc chloride are particularly preferred because they are industrially readily available.

Examples of the monovalent alkali compound used as a raw material for the alkali metal carboxylate include hydroxides of alkali metals (sodium, potassium, etc.), and amines such as ammonia, monoethanolamine, diethanolamine and triethanolamine. . Alkali metal hydroxides such as sodium and potassium are preferable from the viewpoint of high solubility in water when converted into carboxylic acid alkali metal salts and color resistance. A monovalent alkali compound and a carboxylic acid are generally heated at a temperature not lower than the melting point of the carboxylic acid and at which the carboxylic acid does not decompose, preferably 40 to 85°C, more preferably 50 to 80°C, still more preferably. By reacting at 60-75° C., an alkali metal carboxylate is obtained.

Specifically, the reaction between the alkali metal carboxylate and the divalent zinc salt is carried out by separately preparing an aqueous solution containing the divalent zinc salt and an aqueous solution containing the alkali metal carboxylate, and then mixing them. will be For example, it is carried out by adding an aqueous solution containing a divalent zinc salt to an aqueous solution containing an alkali metal carboxylate, or by adding both to separate reaction tanks.

When mixing the carboxylic acid alkali metal salt-containing aqueous solution and the divalent zinc salt-containing aqueous solution, for example, by adding the divalent zinc salt-containing aqueous solution to the carboxylic acid alkali metal salt-containing aqueous solution at once, the obtained carboxylic acid metal salt is obtained. The shape of the particles may become non-uniform and the particle size distribution may become wide. Moreover, there is also a possibility that the precipitated zinc carboxylate may aggregate. Therefore, it is preferable to gradually drop the divalent zinc salt-containing aqueous solution into the carboxylic acid alkali metal salt-containing aqueous solution at an appropriate rate.

The concentration of the alkali metal carboxylate during the production of the metal carboxylate is generally determined from the viewpoint of the productivity of the metal carboxylate and the handling of the aqueous solution containing the alkali metal carboxylate or the resulting slurry of the metal carboxylate. , 1% to 25% by weight, preferably 5% to 15% by weight. If the concentration of the alkali metal carboxylate is less than 1% by mass, the productivity of the metal carboxylate may decrease, which is not practically preferable. If it exceeds 25% by mass, the viscosity of the alkali metal carboxylate-containing aqueous solution or the resulting slurry of the metal carboxylate increases, making it difficult to conduct a uniform reaction.

The concentration of the divalent zinc salt in the divalent zinc salt-containing liquid is determined in terms of the productivity of the carboxylic acid metal salt and the handling properties of the carboxylic acid alkali metal salt-containing aqueous solution or the obtained carboxylic acid metal salt slurry. From the point of view, it is usually 10% by mass to 50% by mass, preferably 10% by mass to 40% by mass.

The reaction between the alkali metal carboxylate and the divalent zinc salt is carried out at a temperature below the softening point of the resulting metal carboxylate, taking into consideration the solubility of the alkali metal carboxylate. 40 to 85°C, more preferably 50 to 80°C. If the reaction temperature is lower than 40°C, the reaction rate between the alkali metal carboxylate and the divalent zinc salt may decrease.

For the purpose of stabilizing the carboxylate metal salt slurry during the reaction between the carboxylate alkali metal salt and the divalent zinc salt and improving the productivity of the carboxylate metal salt, a polyalkylene glycol-based ether, particularly an oxypropylene block is added. A triblock ether having a structure (EO-PO-EO) sandwiched between oxyethylene blocks is preferably present in the carboxylic acid metal salt slurry. The content of the polyalkylene glycol-based ether in the metal carboxylate slurry is usually 0.01 to 5 parts by mass, preferably 0.05 to 2 parts by mass, per 100 parts by mass of the alkali metal carboxylate. Department. The polyalkylene glycol-based ether may be present in the reaction system before reacting the monovalent alkali compound and the carboxylic acid, and before the reaction between the carboxylic acid alkali metal salt and the divalent zinc salt. It may be present in the reaction system.

A carboxylic acid metal salt slurry is obtained by the above method. This carboxylic acid metal salt slurry is used as it is, or the solvent is separated by a centrifugal dehydrator, a filter press, a vacuum rotary filter, etc., and if necessary, washed to remove by-product inorganic salts, and then tray-dried. dryer, rotary dryer, flash dryer, ventilation dryer, spray dryer, fluidized bed dryer, etc. The drying method may be continuous or batchwise, or under normal pressure or vacuum. Furthermore, the dried zinc carboxylate is pulverized as needed. The pulverization method is not particularly limited, and may be, for example, a pin mill, jet mill, atomizer, or the like. The ground zinc carboxylate particles are classified. That is, classification is performed using a multi-stage sieving device or the like that performs sieving by applying vibration, and the particle size distribution is adjusted. In this way, particles of the zinc carboxylate of the present invention can be obtained.

(Physical properties of zinc carboxylate composition)

The zinc carboxylate composition of the present invention has a thixotropic index (viscosity at 6 rpm measured with a Brookfield viscometer of a sample melted at 130°C in 1-octadecene) from the viewpoint of dispersibility in a solvent and dissolution stability. is divided by the viscosity at 10 rpm) is 1.00 to 1.70.

(Carboxylic acid zinc salt solution)
The solvent for dissolving the zinc carboxylate composition of the present invention is not particularly limited, but nonpolar solvents having a boiling point of 170° C. or higher are suitable from the viewpoint of solubility of the zinc carboxylate composition. Specific examples of nonpolar solvents include aliphatic saturated hydrocarbons such as n-decane, n-dodecane, n-hexadecane, and n-octadecane; aliphatic unsaturated hydrocarbons such as octadecene; trioctylphosphine;

The zinc carboxylate solution of the present invention preferably contains 0.01 to 30% by mass of the zinc carboxylate when the total amount of the solvent and the zinc carboxylate is 100% by mass. % or more is more preferable.

In addition, the zinc carboxylate solution of the present invention may contain other components as long as they do not affect the effects of the present invention.

EXAMPLES The present invention will now be described more specifically with reference to examples and comparative examples.

(Example 1: Preparation of zinc carboxylate composition)
A 3 L separable flask was charged with 200 g of a carboxylic acid composition having the composition ratio of "Example 1" in Table 1 and 1500 g of water, and the temperature was raised to 70°C. Then, 116.4 g of a 48% by mass sodium hydroxide aqueous solution was added, and the mixture was stirred at the same temperature (70° C.) for 1 hour to obtain an aqueous alkali metal carboxylate solution. After that, while maintaining the temperature at 70° C., 535.5 g of a 25 mass % zinc chloride aqueous solution was added dropwise to the carboxylic acid alkali metal salt aqueous solution over 1 hour. After the dropwise addition was completed, the mixture was further stirred at 70° C. for 10 minutes. 1500 g of water was added to the resulting aqueous zinc carboxylate slurry, and the mixture was cooled to 60° C. or lower. Then, it is filtered with a suction filter, washed twice with 1000 g of water, and the obtained cake is dried at 75° C. for 72 hours using a tray dryer, pulverized and classified to form zinc carboxylate composition particles. got

(Example 2)
The carboxylic acid composition used was varied as shown in Table 1. Otherwise, zinc carboxylate composition particles were obtained under the same conditions as in Example 1.

(Comparative example 1)
The composition ratio of the carboxylic acid used was changed as shown in Table 1. Otherwise, zinc carboxylate composition particles were obtained under the same conditions as in Example 1.

(Comparative example 2)
The composition ratio of the carboxylic acid used was changed as shown in Table 1. Otherwise, zinc carboxylate composition particles were obtained under the same conditions as in Example 1.

The viscosity (6 rpm and 10 rpm) at 130° C. and the thixotropic index of the zinc carboxylate composition particles of each example and comparative example were measured as follows.

(Viscosity at 130°C)
The viscosities (6 rpm and 10 rpm) of samples melted in 1-octadecene at 130° C. were measured with a Brookfield viscometer.

(thixotropic index)
Value obtained by dividing the viscosity at 6 rpm by the viscosity at 10 rpm

As shown in Tables 1 and 2, when the carboxylic acid constituting the zinc carboxylate composition satisfies the composition ratio of the present invention, the zinc carboxylate solution has low viscosity and low thixotropy. Small change in viscosity.

On the other hand, in Comparative Example 1, although the carboxylic acid constituting the zinc carboxylate composition did not contain the component (B), the thixotropic index was high and the change in viscosity was large.
In Comparative Example 2, although the proportion of component (B) in the carboxylic acid constituting the zinc carboxylate composition was high, the change in viscosity was large.

Claims (3)

A zinc carboxylate composition comprising the following zinc salt of component (A) and zinc salt of component (B),
The ratio of the component (A) in the carboxylic acid constituting the zinc carboxylate composition is 90.0 to 99.9% by mass, and the ratio of the component (B) is 0.1 to 10.0% by mass. and a thixotropic index of 1.00 to 1.70 .

(A) Linear saturated monocarboxylic acid having 8 carbon atoms (B) Linear saturated monocarboxylic acid having 6 carbon atoms
The ratio of the component (A) in the carboxylic acid constituting the zinc carboxylate composition is 92.5 to 99.9% by mass, and the ratio of the component (B) is 0.1 to 7.5% by mass. The zinc carboxylate composition according to claim 1, wherein
A carboxylic acid comprising the zinc carboxylate composition according to claim 1 or 2 and a solvent, wherein the content of the zinc carboxylate composition is 0.01 to 30% by mass. zinc salt solution.