Mixed solvent composition

Abstract

To modify the properties of a solvent comprising 1,1,2,3,3,3-hexafluoropropyl methyl ether and / or 1,1,1,3,3,3-hexafluoroisopropyl methyl ether.SOLUTION: By adding water to 1,1,2,3,3,3-hexafluoropropyl methyl ether and / or 1,1,1,3,3,3-hexafluoroisopropyl methyl ether, the properties thereof as a solvent is modified.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a mixed solvent composition, and more particularly to a solvent composition having excellent solubility for compounds having a perfluoropolyether structure. [Background technology]

[0002] Compounds having a perfluoropolyether structure (for example, Z-tetraol (registered trademark) manufactured by Solvay) have various properties such as high stability, excellent electrical insulation, and low surface energy, and are used as lubricants for magnetic recording media with high surface smoothness, such as hard disks.

[0003] On the other hand, compounds having a perfluoropolyether structure are difficult to dissolve in general organic solvents due to the specificity of their structure, and fluorine-based solvents such as chlorofluorocarbons, hydrofluorocarbons, and perfluorocarbons have been used as solvents. However, these fluorine-based solvents have a large impact on the environment, and their use is being restricted.

[0004] The use of hydrofluoroethers has been proposed as a fluorine-based solvent that dissolves compounds having a perfluoropolyether structure and has a relatively small impact on the environment. For example, Patent Document 1 discloses a composition containing 1,1,1,3,3,3-hexafluoroisopropyl methyl ether for the specific purpose of dissolving compounds having a perfluoropolyether structure. In addition, Patent Document 2 discloses a solvent composition using 1,1,1,3,3,3-hexafluoroisopropyl methyl ether and / or 1,1,2,3,3,3-hexafluoropropyl methyl ether together with fluorine oil.

[0005] The compositions described in these publications have a certain effect as a solvent for a compound having a perfluoropolyether structure, but are not sufficient for dissolving a perfluoropolyether compound having a specific structure. In particular, when the compound having a perfluoropolyether structure further contains a hydroxyl group, a solvent capable of dissolving the compound at a higher concentration is required.

[0006] Furthermore, if the solubility of a solute in a solvent composition can be increased by a simple method, the applicability of the solvent composition will be expanded. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 7128418 [Patent Document 2] Patent No. 7068598 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide a solvent composition that uses 1,1,2,3,3,3-hexafluoropropyl methyl ether (hereinafter referred to as HFPME), 1,1,1,3,3,3-hexafluoroisopropyl methyl ether (hereinafter referred to as HFIPME) or a mixture thereof, and is capable of dissolving a compound having a perfluoropolyether structure containing a hydroxyl group or certain types of compounds at a higher concentration. [Means for solving the problem]

[0009] As a result of intensive research into solving the above problems, the present inventors have surprisingly found that when HFPME and / or HFIPME are used as a solvent, the solubility parameter (hereinafter referred to as SP value) is improved by further adding water, and the compatibility with compounds having a perfluoropolyether structure containing a hydroxyl group and certain types of compounds is increased, i.e., the solubility of compounds having a perfluoropolyether structure containing a hydroxyl group and certain types of compounds is increased, thereby completing the present invention.

[0010] That is, the present invention is characterized by the following points. [1] A mixed solvent composition comprising 1,1,2,3,3,3-hexafluoropropyl methyl ether and / or 1,1,1,3,3,3-hexafluoroisopropyl methyl ether and water. [2] The mixed solvent composition of [1], wherein the water content is 10 ppm by weight or more and less than 800 ppm by weight of the total composition. [3] A mixed solvent composition according to [1] or [2] for dissolving a compound having a perfluoropolyether structure containing a hydroxy group. [4] The mixed solvent composition according to [3], wherein the compound having a perfluoropolyether structure containing a hydroxy group is a compound represented by formula (1). [ka] (In the formula, R 1 and R 2 is a linear divalent group consisting of carbon, hydrogen and fluorine, and n is an integer of 1 or more. [5] A composition comprising 1,1,2,3,3,3-hexafluoropropyl methyl ether and / or 1,1,1,3,3,3-hexafluoroisopropyl methyl ether, water, and a compound having a perfluoropolyether structure containing a hydroxy group. [6] The composition of [5], which is a lubricant for a magnetic recording medium. [7] The composition according to [5] or [6], wherein the compound having a perfluoropolyether structure containing a hydroxy group is a compound represented by formula (1). [ka] (In the formula, R 1 and R 2 is a linear divalent group consisting of carbon, hydrogen and fluorine, and n is an integer of 1 or more. Effect of the Invention

[0011] According to the present invention, a composition can be provided that is particularly suitable as a solvent for compounds having a perfluoropolyether structure containing a hydroxyl group, and is particularly suitable as a lubricant for magnetic recording media. [Brief description of the drawings]

[0012] [Figure 1] 1 is a graph showing the correlation between the amount of water added to HFPME and the SP value. [Diagram 2] 1 is a graph showing the correlation between the amount of water added to HFIPME and the SP value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail.

[0014] The mixed solvent composition of the present invention comprises HFPME, HFIPME or a mixture thereof, and water. As described above, HFPME and HFIPME are compounds known as hydrofluoroethers. When used for the purpose of the present invention, commercially available products can be used, or products recovered by distillation or the like from those used for the purpose of the present invention or other purposes can be used. HFPME, also known as HFE-356mec, has the following structure: [ka] As HFPME, a specific optical isomer can be used, but a mixture thereof can also be used. HFIPME, also known as HFE-356mmz, has the following structure: [ka]

[0015] The type of water contained as an essential component in the mixed solvent composition of the present invention is not particularly limited, and can be distilled water, ion-exchanged water, filtered water, tap water, purified water such as ultrapure water obtained with a commercially available pure water generator, etc. It is preferable that the water has acids, bases, salts, etc. reduced to below the detection limit. The pH of the water contained in the mixed solvent composition of the present invention is preferably 6 or more and 8 or less.

[0016] The amount of water contained in the mixed solvent composition of the present invention is preferably 10 ppm by weight or more and less than 800 ppm by weight. By making it 10 ppm by weight or more, the effect of increasing the SP value described below is observed, and by making it less than 800 ppm by weight, at least one of HFPME and HFIPME and water can be mixed uniformly. The amount of water added can be measured by a conventional method such as the Karl Fischer method.

[0017] The SP value is a known parameter proposed by Hildebrand et al. (see, for example, the Journal of the Adhesion Society of Japan (Vol. 53, No. 4, 129), which will be described later), and is defined by the following mathematical formula. δ = (E / V) 1 / 2

[0018] Here, δ is the SP value, E is the energy of vaporization, and V is the molar volume. It is widely known to those skilled in the art that the closer the SP values ​​of a solute and a solvent are, the greater the solubility. There are.

[0019] Incidentally, compounds having a perfluoropolyether structure are known to have a relatively small SP value, and generally, fluorine-based solvents such as HFPME and HFIPME are also known to have a relatively small SP value. From the viewpoint of the SP values ​​of both, as described in the above-mentioned patent documents, it can be understood that fluorine-based solvents such as HFPME and HFIPME are suitable as solvents for compounds having a perfluoropolyether structure. Here, when a compound having a perfluoropolyether structure contains a hydroxyl group, its SP value becomes large, and therefore the difference between the SP value of such a compound and the SP value of a fluorine-based solvent such as HFPME or HFIPME becomes large, and there is a problem that the fluorine-based solvent such as HFPME or HFIPME is not suitable as a solvent for a compound having a perfluoropolyether structure containing a hydroxyl group. The present inventors have now discovered for the first time that the SP values ​​of HFPME and HFIPME can be increased by adding a small amount of water.

[0020] By adding water to HFPME or HFIPME, the SP value of HFPME or HFIPME can be increased, making it possible to use HFPME or HFIPME as a suitable solvent for dissolving compounds that were previously considered unsuitable for dissolving, such as compounds having a perfluoropolyether structure containing a hydroxyl group. This is of great technological significance in terms of expanding the applications of HFPME and HFIPME as a solvent.

[0021] Here, the perfluoropolyether structure of the compound having the perfluoropolyether structure may be a straight-chain structure or a branched structure.Constituent unit is not particularly limited, but for example, perfluoromethyl ether, perfluoroethyl ether, perfluoropropyl ether, perfluorobutyl ether, perfluoropentyl ether, perfluorohexyl ether, perfluoro(methyl)ethyl ether, and the structure consisting of a combination of two or more selected from them are preferred.

[0022] The number of hydroxy groups contained in the compound having a perfluoropolyether structure is not particularly limited as long as it is one or more, and more preferably two or more.

[0023] In the present invention, the compound having a perfluoropolyether structure containing a hydroxy group is more preferably a compound represented by the following formula (1).

[0024] [ka] (In the formula, R 1 and R 2 is a linear divalent group consisting of carbon, hydrogen and fluorine, and n is an integer of 1 or more.

[0025] The compounds represented by formula (1) are used as lubricants for magnetic recording media, and the mixed solvent composition of the present invention is suitably used for these compounds. As a lubricant for magnetic recording media represented by formula (1), D-4OH manufactured by MORESCO Corporation is commercially available. The SP value of this compound was estimated to be 7.5 (cal / cm2) according to the method described in the Journal of the Adhesion Society of Japan (Vol. 53, No. 4, 129). 3 ) (1 / 2) It is expected to be about that amount.

[0026] Similarly, the mixed solvent composition of the present invention is preferably used for the following compounds and solvents from the viewpoint of their SP values, as in the case of the compound represented by the above formula (1). The SP values ​​of each compound are shown below. Diamyl ether: 7.3 Isoprene: 7.4 Shell TS28 Solvent: 7.4 Silicon tetrachloride: 7.4 Triethylamine: 7.4 Hexene-1:7.4 n-Heptane: 7.4 Diethyl ether: 7.4 n-Heptane: 7.4 Ethyl isobutyl ether: 7.5 APCO #18 Solvent: 7.5 Butyl stearate: 7.5 n-Octane: 7.5 EXAMPLES

[0027] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

[0028] (Increase in SP value of HFPME by adding water) The SP value of HFPME was calculated by adding water using the following formula: δ = (E / V) 1 / 2

[0029] Here, δ is the SP value, E is the evaporation energy, and V is the molar volume. The results are shown in Table 1 and Figure 1.

[0030] [Table 1]

[0031] (Increase in SP value of HFIPME by adding water) The SP value of HFIPME was calculated by adding water in the same manner. The results are shown in Table 2 and Figure 2.

[0032] [Table 2] (Increase in SP value of HFPME and HFIPME mixed solvent by adding water) The SP value of a 1:1 mixture of HFPME and HFIPME was calculated by adding water in the same manner. The results are shown in Table 3. [Table 3]

[0033] As shown in Table 1 and FIG. 1, Table 2 and FIG. 2, and Table 3, the SP value becomes large by actively adding water to HFPME or HFIPME. As mentioned above, it is known that when the SP values ​​of a solute and a solvent are close, the solubility of the solute increases. [ka] The SP value is 7.5(cal / cm 3 ) (1 / 2) Therefore, the fact that an increase in the SP value of HFPME or HFIPME by the addition of water was confirmed means that HFPME or HFIPME containing water is more suitable as a solvent for the above compound than HFPME or HFIPME without water.

[0034] From the same viewpoint, it can also be said that the mixed solvent composition of the present invention is suitable for dissolving the above-mentioned compounds.

Claims

1. A mixed solvent composition comprising 1,1,2,3,3,3-hexafluoropropyl methyl ether and / or 1,1,1,3,3,3-hexafluoroisopropyl methyl ether and water.

2. 2. The mixed solvent composition according to claim 1, wherein the water content is from 10 ppm by weight to less than 800 ppm by weight of the total composition.

3. The mixed solvent composition according to claim 1 or 2, for dissolving a compound having a perfluoropolyether structure containing a hydroxy group.

4. 4. The mixed solvent composition according to claim 3, wherein the compound having a perfluoropolyether structure containing a hydroxy group is a compound represented by formula (1). 【Chemistry 1】 (In the formula, R 1 and R 2 is a linear divalent group consisting of carbon, hydrogen and fluorine, and n is an integer of 1 or more.

5. A composition comprising 1,1,2,3,3,3-hexafluoropropyl methyl ether and / or 1,1,1,3,3,3-hexafluoroisopropyl methyl ether, water and a compound having a perfluoropolyether structure containing a hydroxy group.

6. The composition of claim 5 which is a lubricant for a magnetic recording medium.

7. 7. The composition according to claim 5, wherein the compound having a perfluoropolyether structure containing a hydroxy group is a compound represented by formula (1). 【Chemistry 2】 (In the formula, R 1 and R 2 is a linear divalent group consisting of carbon, hydrogen and fluorine, and n is an integer of 1 or more.

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