Zinc carboxylate compositions and zinc carboxylate solutions containing zinc carboxylate compositions

Abstract

The present invention improves the viscosity stability, heat resistance, and solubility stability of zinc carboxylate in the use of dissolving zinc carboxylate in a solvent or melting zinc carboxylate itself. The carboxylic acid constituting zinc carboxylate contains 0.5 to 6.0 mass% of component (A), 0.05 to 1.2 mass% of component (B), and 88.0 to 98.0 mass% of component (C), and the mass ratio [(A) / (B)] of component (A) to component (B) is 99 / 1 to 75 / 25. (A) Linear saturated carboxylic acid having 12 to 22 carbon atoms. (B) Linear unsaturated carboxylic acid having 18 carbon atoms and having one unsaturated bond which is a trans double bond. (C) Linear unsaturated carboxylic acid having 18 carbon atoms and having one unsaturated bond which is a cis double bond.

Description

TECHNICAL FIELD

[0001] The present application relates to a carboxylic acid metal salt capable of improving heat resistance (low color tone), viscosity stability, and solubility stability of zinc carboxylate. Zinc carboxylate can be used in: a thickening agent for a lubricating grease for preventing wear of metals against each other, an additive for lubricating oil, a precursor raw material for quantum dots of a semiconductor, and the like, and in a use in which zinc carboxylate is dissolved in a solvent or oil or zinc carboxylate itself is melted in a manufacturing process. BACKGROUND

[0002] Conventionally, it is widely known that a carboxylic acid metal salt can be used in: a thickening agent for a lubricating grease for preventing wear of metals against each other, an additive for lubricating oil, a precursor raw material for quantum dots of a semiconductor, and the like, and in a use in which zinc carboxylate is dissolved in a solvent or oil or zinc carboxylate itself is melted in a manufacturing process.

[0003] For example, as long as it is a thickening agent for a lubricating grease, when a mechanical device is operated, parts come into sliding contact or rotational contact with each other, and thus metal surfaces are worn. For the purpose of preventing wear of metal surfaces thus generated or for the purpose of controlling wear, zinc carboxylate is used.

[0004] In Patent Literature 1, a lubricating grease composition composed of a base oil having a viscosity index of 190 or less and a dynamic viscosity at 40°C of 200 mm 2 / s or more and zinc stearate is described.

[0005] Further, as a zinc precursor for obtaining quantum dots, zinc oleate is used, which can be dissolved at a high temperature and used as a reaction raw material. Further, Citation Literature 2 relates to the preparation of a zinc precursor solution for obtaining quantum dots, and describes that zinc acetate is reacted with oleic acid in 1-octadecene at 120°C for 1 hour to obtain a zinc oleate solution.

[0006] Prior Art Documents

[0007] Patent Literature

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 2016-121296

[0009] Patent Literature 2: Japanese Patent Application Laid-Open No. 2011-194562 SUMMARY

[0010] Technical Problem to be Solved by the Invention

[0011] However, the grease composition described in Patent Literature 1 can reduce the sliding load and impart high lubricity, but there is still a technical problem in terms of the solubility stability of the carboxylate metal salt in the base oil in a higher high-viscosity state in the field of the environment. In addition, when it is used by being melted, if the melted state is maintained, the color tone changes due to coloring, or the viscosity change becomes large due to the stirring conditions, there is a risk of quality variation. Further, the zinc oleate solution described in Patent Literature 2 sometimes separates, and there is a risk that a quantum dot of stable quality cannot be obtained.

[0012] The technical problem of the present application is to improve the heat resistance (low color tone), viscosity stability, and solubility stability of zinc carboxylate in the use of dissolving zinc carboxylate in a solvent or using it by being melted.

[0013] Technical means for solving the technical problem

[0014] The present inventors have conducted intensive research in order to solve the above technical problem, and as a result, have found that when the carboxylic acid constituting the zinc carboxylate has a specific composition, the heat resistance, viscosity stability, and solubility stability of the carboxylate metal salt can be improved in the use of dissolving it in a solvent, thereby completing the present application.

[0015] That is, the present application is described below as (1) and (2).

[0016] (1) A zinc carboxylate characterized by containing 0.5 to 6.0 mass% of the following component (A), 0.05 to 1.2 mass% of the following component (B), and 88.0 to 98.0 mass% of the following component (C) in the carboxylic acid constituting the zinc carboxylate, and the mass ratio [(A) / (B)] of the component (A) to the component (B) is 99 / 1 to 75 / 25.

[0017] (A) A linear saturated carboxylic acid having 12 to 22 carbon atoms.

[0018] (B) A linear unsaturated carboxylic acid having 18 carbon atoms having one unsaturated bond, and the unsaturated bond is a trans double bond.

[0019] (C) A linear unsaturated carboxylic acid having 18 carbon atoms having one unsaturated bond, and the unsaturated bond is a cis double bond.

[0020] (2) A zinc carboxylate solution characterized by containing the zinc carboxylate of (1) and a solvent, and the content of the zinc carboxylate is 0.01 to 30 mass%.

[0021] Effects of the Invention

[0022] According to the present application, it is possible to improve the heat resistance, viscosity stability, and solubility stability of the zinc carboxylate of the present application in the use of dissolving the zinc carboxylate for a drying agent for paint, an additive for lubricating oil, a precursor material for quantum dots, and the like in a solvent. DETAILED DESCRIPTION

[0023] (Zinc carboxylate)

[0024] The carboxylic acid as a raw material of the alkali metal salt of carboxylic acid contains the above-described component (A), component (B), and component (C).

[0025] Here, the component (A) is a straight-chain saturated carboxylic acid having 12 to 22 carbon atoms. The number of carbon atoms of the straight-chain saturated carboxylic acid is further preferably 14 or more and further preferably 20 or less. In addition, the component (A) can be one kind or two or more kinds.

[0026] The component (B) is a straight-chain unsaturated carboxylic acid having 18 carbon atoms having one unsaturated bond, and the unsaturated bond is a trans double bond. The carboxylic acid does not have a triple bond or a cis double bond. In addition, the component (B) can be one kind or two or more kinds.

[0027] The position of the trans double bond in the component (B) is not particularly limited, and elaidic acid having a double bond at the 9-position, isoeikosanoic acid having a double bond at the 11-position, and more preferably elaidic acid can be preferably exemplified.

[0028] The component (C) is a straight-chain unsaturated carboxylic acid having 18 carbon atoms having one unsaturated bond, and the unsaturated bond is a cis double bond. The carboxylic acid does not have a triple bond or a trans double bond. In addition, the component (C) can be one kind or two or more kinds.

[0029] The position of the cis double bond in the component (C) is not particularly limited, and oleic acid having a double bond at the 9-position, cis-isoeikosanoic acid having a double bond at the 11-position, and more preferably oleic acid can be preferably exemplified.

[0030] When the total amount of the carboxylic acid constituting the zinc carboxylate is set to 100 mass%, the amount of the component (A) is set to 0.5 to 6.0 mass%. When the amount of the component (A) is less than 0.5 mass%, the thixotropic index of the obtained zinc carboxylate becomes large, and the solubility stability becomes low, and thus it is set to 0.5 mass% or more, and further preferably 1.5 mass% or more. On the other hand, when the amount of the component (A) is more than 6.0 mass%, precipitation occurs at the time of dissolution, and the stability becomes poor, and thus it is set to 6.0 mass% or less, and further preferably 5.5 mass% or less.

[0031] When the total amount of the carboxylic acid constituting the zinc carboxylate is taken as 100 mass%, the amount of component (B) is taken as 0.05 to 1.2 mass%. Thus, the solubility stability is improved. From this viewpoint, the amount of component (B) is further preferably 0.10 mass% or more, and furthermore, further preferably 1.0 mass% or less.

[0032] When the total amount of the carboxylic acid constituting the zinc carboxylate is taken as 100 mass%, the amount of component (C) is taken as 88.0 to 98.0 mass%. Thus, the color phase is improved, and the solubility stability is improved. From this viewpoint, the amount of component (C) is further preferably 89.0 mass% or more, and furthermore, further preferably 95.0 mass% or less.

[0033] In the present application, the mass ratio of component (A) to component (B) [(A) / (B)] is taken as 99 / 1 to 75 / 25. Thus, the solubility stability is improved. From this viewpoint, the mass ratio [(A) / (B)] is further preferably 98 / 2 to 80 / 20.

[0034] The carboxylic acid constituting the zinc carboxylate composition of the present application can be composed of components (A), (B), and (C), or, in addition to components (A), (B), and (C), other component (D) can be further contained as a remaining portion. That is, the content of other component (D) is a remaining portion after the total amount of components (A), (B), and (C) is subtracted from 100 mass%, and is preferably 10 mass% or less, further preferably 5 mass% or less, and can also be 0.0 mass%.

[0035] The carboxylic acid constituting other component (D) preferably has two or more double bonds, and further preferably has two or three double bonds. Furthermore, the number of carbon atoms of the carboxylic acid constituting other component (D) is preferably 16 to 22, further preferably 16 to 18, and particularly preferably 18.

[0036] As to the double bond in component (D), it can be cis or trans, and as the position of the double bond, linoleic acid having cis double bonds at positions 9 and 12, linoelaidic acid having trans double bonds at positions 9 and 12, and linolenic acid having cis double bonds at positions 9, 12, and 15 can be preferably cited, and more preferably, linoleic acid and linolenic acid, and further preferably, linoleic acid.

[0037] (Method for producing zinc carboxylate)

[0038] As a main production method of the carboxylate metal salt, there are a direct method and a double decomposition method. The direct method is a method of obtaining a carboxylate metal salt by directly reacting a carboxylic acid with a metal oxide or a metal hydroxide in a molten state. On the other hand, the double decomposition method is a method of obtaining a carboxylate metal salt by reacting an aqueous solution of a carboxylate alkali metal salt with an inorganic metal salt.

[0039] The direct method has advantages in equipment, such as a simple process and a small equipment scale, but on the other hand, has the following technical problems.

[0040] (a) Lack of reaction completeness, a large amount of unreacted carboxylic acid, a metal oxide or a metal hydroxide of the raw material remains in the carboxylate metal salt.

[0041] (c) Since the reactivity is low, the metal oxide or the metal hydroxide has been reacted in an equimolar amount or more with respect to the carboxylic acid in the past, and thus a basic carboxylate metal salt (a mono salt) remains in the obtained carboxylate metal salt, the melting point is high, or the solubility is low.

[0042] On the other hand, the double decomposition method has advantages in quality, such as a small amount of unreacted carboxylic acid, a metal compound of the raw material, a different kind of metal, a good color tone, and a fine powder, which are completely opposite to the above-described direct method, but on the other hand, also has the following technical problems.

[0043] (a) A large manufacturing equipment is required.

[0044] (b) The dispersibility of the reaction slurry in water is unstable, and the workability is poor.

[0045] The zinc carboxylate of the present application can be produced by any one of the direct method or the double decomposition method, and from the viewpoint of improving the heat resistance, the viscosity stability in a molten state, and the solubility stability in a solvent, the zinc carboxylate produced by the double decomposition method is further preferred.

[0046] As the monovalent base compound which is a raw material of the carboxylate alkali metal salt, there are hydroxides of alkali metals (sodium, potassium, and the like), and amines such as ammonia, monoethanolamine, diethanolamine, triethanolamine, and the like. From the viewpoint of the solubility in water when the carboxylate alkali metal salt is produced and the color resistance, the hydroxides of alkali metals such as sodium and potassium are preferred. The monovalent base compound is reacted with the carboxylic acid at a temperature of the melting point of the carboxylic acid or higher, and a temperature at which the carboxylic acid does not decompose, preferably at 40 to 85°C, more preferably at 50 to 80°C, and further preferably at 60 to 75°C, to obtain the carboxylate alkali metal salt.

[0047] The zinc carboxylate of the present application is a carboxylate metal salt particle obtained by reacting the above-obtained carboxylate alkali metal salt with a divalent zinc salt in an aqueous solution. Specifically, the above divalent zinc salt is a salt of a divalent zinc metal and an inorganic acid or an organic acid. As the divalent inorganic zinc salt, zinc sulfate, zinc chloride, zinc nitrate are preferred. Among them, zinc sulfate and zinc chloride are particularly preferred from the viewpoint of easy availability in industry.

[0048] Specifically, the above reaction is carried out by separately preparing an aqueous solution containing the divalent zinc salt and an aqueous solution containing the carboxylate alkali metal salt, and then mixing them. For example, the reaction is carried out by adding the aqueous solution containing the divalent zinc salt to the aqueous solution containing the carboxylate alkali metal salt, or by adding both in another reaction vessel.

[0049] When the aqueous solution containing the carboxylate alkali metal salt and the aqueous solution containing the divalent zinc salt are mixed, for example, if the aqueous solution containing the divalent zinc salt is added at once to the aqueous solution containing the carboxylate alkali metal salt, the shape of the obtained carboxylate metal salt particle becomes non-uniform, and there is a possibility that the particle size distribution becomes wide. In addition, there is a possibility that the precipitated zinc carboxylate is aggregated. Therefore, it is preferred that the aqueous solution containing the divalent zinc salt is gradually added dropwise to the aqueous solution containing the carboxylate alkali metal salt at a moderate rate.

[0050] From the viewpoint of the productivity of the carboxylate metal salt, and the operability of the aqueous solution containing the carboxylate alkali metal salt or the obtained carboxylate metal salt slurry, the concentration of the carboxylate alkali metal salt at the time of preparation of the carboxylate metal salt is usually 1 to 20 mass%, and preferably 5 to 15 mass%. When the concentration of the carboxylate alkali metal salt is less than 1 mass%, the productivity of the carboxylate metal salt can be decreased, and it is not preferred in practical use. When the concentration of the carboxylate alkali metal salt is more than 20 mass%, the viscosity of the aqueous solution containing the carboxylate alkali metal salt or the obtained carboxylate metal salt slurry increases, and sometimes it is difficult to carry out the reaction uniformly.

[0051] In addition, from the viewpoint of the productivity of the carboxylate metal salt, and the operability of the aqueous solution containing the carboxylate alkali metal salt or the obtained carboxylate metal salt slurry, the concentration of the divalent zinc salt in the aqueous solution containing the divalent zinc salt is usually 10 to 50 mass%, and preferably 10 to 40 mass%.

[0052] The reaction of the carboxylate alkali metal salt and the divalent zinc salt is carried out at a temperature below the softening point of the obtained carboxylate metal salt, and the temperature is preferably 40 to 85°C, and more preferably 50 to 80°C, taking into account the solubility of the carboxylate alkali metal salt. When the reaction temperature is less than 40°C, the reaction rate of the carboxylate alkali metal salt and the divalent zinc salt can be decreased.

[0053] For the purpose of stabilizing the carboxylic acid metal salt slurry at the time of the reaction of the carboxylic acid alkali metal salt with the divalent zinc salt, thereby improving the productivity of the carboxylic acid metal salt, it is preferable that a polyalkylene glycol ether, particularly a triblock ether having a structure in which an oxypropylene block is sandwiched by oxyethylene blocks (EO-PO-EO), is present in the carboxylic acid metal salt slurry. The content of the polyalkylene glycol ether in the carboxylic acid metal salt slurry is usually 0.01 parts by mass to 5 parts by mass, and preferably 0.05 parts by mass to 2 parts by mass, relative to 100 parts by mass of the carboxylic acid alkali metal salt. In addition, the polyalkylene glycol ether can be present in the reaction system before the reaction of the monovalent alkali compound with the carboxylic acid, or can be present in the reaction system before the reaction of the carboxylic acid alkali metal salt with the divalent zinc salt.

[0054] By the above method, a carboxylic acid metal salt slurry can be obtained. The solvent is separated directly, or using a centrifugal dehydrator, a filter press, a vacuum rotary filter, or the like, and, if necessary, washed, and the inorganic salt by-produced is removed, and the carboxylic acid metal salt slurry is dried using a cabinet dryer, a rotary dryer, an air flow drying device, a through-air dryer, a spray dryer, a fluidized bed type drying device, or the like. The drying method can be any one of continuous or batch, or under normal pressure or vacuum. Further, if necessary, the dried carboxylic acid zinc is pulverized. The pulverization method is not particularly limited, and, for example, a pin mill, a jet mill, an atomizer, or the like can be used. The carboxylic acid zinc after pulverization is classified. That is, using a multi-stage sifter device that performs sifting by imparting vibration, or the like, the classification is performed, and the particle size distribution is adjusted. Thus, the carboxylic acid zinc particles of the present application can be obtained.

[0055] (Physical properties of the carboxylic acid zinc)

[0056] For the carboxylic acid zinc of the present application, the viscosity stability (value obtained by dividing the viscosity at 1 rpm of a test material after melting at 100°C by the viscosity at 2.5 rpm, measured using a B-type viscometer) is 1.04 to 1.10, and preferably 1.04 to 1.09, from the viewpoint of dispersibility in a solvent, and dissolution stability.

[0057] Further, from the viewpoint of heat resistance (low tint), when melted at 100°C, the tint is preferably 3 or less, and further preferably 2 or less, in terms of Gardner. Further, when kept in a molten state at 100°C for 1 hour, the tint is preferably 4 or less, and further preferably 3 or less, in terms of Gardner. As the change in tint, the difference in the tint after 1 hour from the time of melting and the tint immediately after melting is preferably 2 or less, and further preferably 1 or less, in terms of Gardner.

[0058] (Carboxylic acid zinc solution)

[0059] The solvent used to dissolve the zinc carboxylate of the present application is not particularly limited, and from the viewpoint of solubility of the zinc carboxylate, a non-polar solvent having a boiling point of 170°C or higher is suitably exemplified. As the non-polar solvent, specifically, for example, aliphatic saturated hydrocarbons such as n-decane, n-dodecane, n-hexadecane, n-octadecane, and the like; aliphatic unsaturated hydrocarbons such as 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, and the like; trioctylphosphine, and the like can be exemplified.

[0060] Among them, aliphatic saturated hydrocarbons are preferred, and aliphatic saturated hydrocarbons having a carbon number of 12 to 18 are more preferred.

[0061] In the zinc carboxylate solution of the present application, when the total amount of the solvent and the zinc carboxylate is set to 100 mass%, it is preferred to contain 0.01 to 30 mass% of the zinc carboxylate.

[0062] Example

[0063] Hereinafter, the present application will be further specifically described by citing examples and comparative examples.

[0064] (Example 1: Preparation of zinc carboxylate)

[0065] Into a 3L separable flask, 250 g of a carboxylic acid composition having the composition ratio of "No. 1" of Table 1 and 2500 g of water were added, and warmed to 70°C. Subsequently, 77.2 g of a 48 mass% sodium hydroxide aqueous solution was added, and stirred at the same temperature (70°C) for 1 hour to obtain an aqueous solution of a carboxylic acid alkali metal salt. Then, while maintaining 70°C, 151.2 g of a 25 mass% zinc chloride aqueous solution was added dropwise to the aqueous solution of the carboxylic acid alkali metal salt over 1 hour. After the completion of the dropwise addition, further stirring was performed at 70°C for 1 hour. To the obtained slurry of the zinc carboxylate aqueous solution, 1500 g of water was added, and cooled to 60°C or lower. Then, filtration was performed using a suction filter, and water washing was performed twice using 1000 g of water. The obtained filter cake was dried using a cabinet dryer at 75°C for 72 hours, and pulverized and classified to obtain zinc carboxylate particles.

[0066] (Example 2)

[0067] Preparation was performed under the same conditions as Example 1 except that the carboxylic acid composition used was changed to No. 2 shown in Table 1.

[0068] (Comparative Example 1)

[0069] Preparation was performed under the same conditions as Example 1 except that the composition ratio of the carboxylic acid used was changed to No. 3 shown in Table 1.

[0070] (Comparative Example 2)

[0071] Example 1 except that the composition ratio of the carboxylic acid to be used was changed to No. 4 shown in Table 1. The preparation was performed under the same conditions as in Example 1.

[0072] Then, for the zinc carboxylate particles of Examples 1, 2 and Comparative Examples 1, 2 and 3, the viscosity at 100°C (1 rpm and 2.5 rpm), the viscosity stability, and the heat resistance were measured in the following manner, respectively, and the results of the measurement are shown in Table 2.

[0073] (Viscosity at 100°C)

[0074] The viscosity (1 rpm and 2.5 rpm) of the sample melted at 100°C was measured using a B-type viscometer.

[0075] (Viscosity stability)

[0076] The value obtained by dividing the viscosity at 1 rpm by the viscosity at 2.5 rpm

[0077] (Heat resistance)

[0078] The color tone of the sample immediately after complete melting at 100°C and the color tone of the sample after keeping the melted state at 100°C for 1 hour were measured using the Gardner color scale. The Gardner of all the samples immediately after melting was 2. The color tone after keeping for 1 hour is shown in Table 2. Further, the difference between the color tone immediately after melting and the color tone after keeping for 1 hour was calculated and shown in parentheses in Table 2. In addition, the measurement was performed in accordance with JIS K-0071-2.

[0079] [Preparation and evaluation of zinc carboxylate solution]

[0080] Into a 2-liter SUS round bottom flask, 800.0 g of 1-octadecene and 200.0 g of the zinc carboxylate of each example of Table 2 were put, and under nitrogen bubbling, mixed at 300°C for 5 hours to obtain a solution. After the mixing, the temperature of the solution was cooled to room temperature to obtain a sample.

[0081] For the obtained sample, the dissolution stability was confirmed by visual observation. The result thereof is shown in Table 3.

[0082] [Table 1]

[0083]

[0084] [Table 2]

[0085]

[0086] [Table 3]

[0087] Raw material zinc carboxylate Dissolution stability Example 1 Zinc carboxylate 1 ○ Example 2 Zinc carboxylate 2 ○ Comparative example 1 Zinc carboxylate 3 Separation Comparative example 2 Zinc carboxylate 4 Haze

[0088] As shown in Tables 1 to 3, when the carboxylic acid constituting the zinc carboxylate satisfies the composition ratio of the present application, the viscosity stability and heat resistance of the zinc carboxylate melt are good, and the dissolution stability of the zinc carboxylate solution is high.

[0089] In Comparative Example 1, the ratio of components (A) and (B) and (A) / (B) are outside the range of the present application, the viscosity stability is low, and separation of the zinc carboxylate is observed.

[0090] In Comparative Example 2, the ratio of component (B) and (A) / (B) are outside the range of the present application, the viscosity stability is low, the color tone changes greatly after 1 hour, and the solution is observed to be turbid.

Claims

1. A zinc carboxylate composition, characterized in that, The carboxylic acid constituting the zinc carboxylate composition contains 1.5 to 5.5 mass% of the following component (A), 0.10 to 1.0 mass% of the following component (B), and 89.0 to 95.0 mass% of the following component (C), and the mass ratio [(A) / (B)] of the component (A) to the component (B) is 98 / 2 to 80 / 20, (A) a linear saturated carboxylic acid having 16 to 18 carbon atoms, (B) a linear unsaturated carboxylic acid having 18 carbon atoms having one unsaturated bond, and the unsaturated bond being a trans double bond, (C) a linear unsaturated carboxylic acid having 18 carbon atoms having one unsaturated bond, and the unsaturated bond being a cis double bond.

2. A zinc carboxylate solution characterized in that, A solvent containing the zinc carboxylate composition of claim 1 in an amount of 0.01 to 30 mass%.

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