JP3236087B2 - Surfactant for producing polymerizable magnetic fluid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surfactant for producing a polymerizable magnetic fluid comprising a linear aliphatic carboxylic acid.

[0002]

2. Description of the Related Art Magnetic fluids are used in the field of magnetic fluid seals, optical materials, and the like because of their unique properties, such as behaving as a ferromagnetic liquid. Generally, a magnetic fluid is composed of magnetic fine particles, a surfactant, and a dispersion medium. In recent years, using a polymerizable monomer as a dispersion medium,
Attempts have been made to create new magnetic films for applications such as magnetic shielding, visualization of magnetic recording patterns, and magnetic flaw detection. Further, the polymerizable magnetic fluid is used as a magnetic fluid adhesive for connecting magnetic materials.

Conventionally, in the production of magnetic fluids, as a surfactant, a compound having a bent molecular skeleton represented by oleic acid or linoleic acid, or a compound having many functional groups or side chains in one molecule. Was used. However, with such a surfactant, it is not easy to stably disperse the magnetic fine particles in the polymerizable dispersion medium,
Large amounts of surfactant were required for dispersion. Moreover,
Excessive use of a surfactant causes poor curing during polymerization of the dispersion medium.

[0004] In addition, although conventional surfactants are used in excess, undesirable phenomena such as unexpected increase in viscosity and solidification occur together. This is probably because the magnetic particles acted as a catalyst to cause radical polymerization.

[0005]

Accordingly, a polymerizable magnetic fluid which exhibits stable dispersibility of magnetic fine particles, does not undergo polymerization during storage, and cures only at the time of polymerization, and an interface suitable for producing this polymerizable magnetic fluid. Activators have long been desired.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted studies to develop a surfactant suitable for producing a polymerizable magnetic fluid, and as a result, have found that a linear aliphatic carboxylic acid having a specific molecular structure has been obtained. However, they have found that they are suitable for producing a polymerizable magnetic fluid as a surfactant and have completed the present invention. That is, the present invention

[0007]

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[0008] (wherein, R represents an alkyl group having 1 to 12 carbon atoms, n represents an integer of 1 to 25, m each represents an integer of 10 to 12) from a linear aliphatic carboxylic acid represented by the Becoming heavy
The present invention relates to a surfactant for producing a compatible magnetic fluid .

In the above general formula, a linear aliphatic carboxylic acid in which R is a hydrogen atom, a linear aliphatic carboxylic acid in which n is 0, a linear aliphatic carboxylic acid in which m is less than 10, and the like. When used as a surfactant for a polymerizable magnetic fluid, the dispersibility of the magnetic fine particles decreases, and the polymerization of the dispersion medium easily occurs during storage. A linear aliphatic carboxylic acid wherein R is an alkyl group having more than 12 carbon atoms; a linear aliphatic carboxylic acid wherein n exceeds 25; or a linear aliphatic carboxylic acid wherein m is 13 or more. In such cases, not only is raw material difficult to obtain and synthesis is difficult, but also the amount of surfactant required for the synthesis of a polymerizable magnetic fluid increases, which is not economical. Soluble magnetic fluids tend to cause poor curing during polymerization.

Specific examples of the linear aliphatic carboxylic acid represented by the above general formula of the present invention include CH ₃ O (C ₂ H ₄
O) ₂ (CH ₂ ) ₁₀ COOH, CH ₃ O (C ₂ H ₄ O) ₂ (C
_{H 2) 11 COOH, CH 3} O (C 2 H 4 O) 2 (CH 2) 12 C
OOH, CH ₃ O (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₀ COOH,
CH ₃ O (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₁ COOH, CH ₃ O
(C ₂ H ₄ O) ₃ (CH ₂ ) ₁₂ COOH, H (C ₂ H ₄ O) ₃
(CH ₂ ) ₁₀ COOH, H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₁ C
OOH, H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₂ COOH, C ₄ H ₉
OC ₂ H ₄ O (CH ₂ ) ₁₂ COOH, C ₄ H ₉ O (C ₂ H
₄ O) ₂ (CH ₂ ) ₁₂ COOH, C ₄ H ₉ O (C ₂ H ₄ O)
₃ (CH ₂ ) ₁₂ COOH, C ₁₂ H ₂₅ O (C ₂ H ₄ O) ₂ (C
_{H 2) 10 COOH, C 12} H 25 0 (C 2 H 4 O) 25 (CH 2)
₁₀ COOH, and the like.

The method for producing the linear aliphatic carboxylic acid is not limited at all, but a typical method will be described below.

As shown in the following reaction formula, the alkyl carboxylic acid is esterified by a conventional method.

[0013]

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(The definitions of R and m are as described above.) The esterification reaction employs well-known alcohol, solvent, catalyst and temperature conditions. On the other hand, as represented by the following reaction formula, an alkyl ether alcohol is converted to an alkoxide by a conventional method using sodium and potassium iodide in a solvent such as toluene, benzene or tetrahydrofuran.

[0015]

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Into the solution containing the alkoxide compound obtained by the above method, the previously obtained ester of the halogenated alkyl carboxylic acid is dropped, and the following reaction is carried out.

[0017]

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The reaction temperature is usually in the range of 40 to 150 ° C., and the reaction solvent used is the same as that used for preparing the alkoxide. The molar ratio of both reactants used is usually ester / alkoxide = 0.2
To 2.

After the reaction, the reaction solvent is distilled off under reduced pressure, an aqueous NaOH solution is newly added, and the ester bond is hydrolyzed by a conventional method to give a carboxylate compound as shown below.

[0020]

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Next, an aqueous acid solution such as an aqueous HCl solution is added dropwise to the reaction solution until the pH becomes 1, and the carboxylate compound is converted into the carboxylic acid compound targeted by the present invention. After the reaction, the mixture is extracted and washed according to a conventional method, and then a crude product is obtained by distilling off an alkyl ether alcohol as a raw material under reduced pressure. By purifying the crude product using a column, the target product, a linear aliphatic carboxylic acid, is obtained.

The surfactant of the present invention is contained in a polymerizable dispersion medium.
When manufacturing polymerizable magnetic fluid by dispersing magnetic fine particles
The polymerizable magnetic fluid using the surfactant is generally produced by the following method.

That is, a method for producing a magnetic fluid in which the magnetic particles are magnetite is exemplified as follows. An aqueous solution comprising a ferrous salt and a ferric salt is reacted with an aqueous alkali solution such as sodium hydroxide to generate fine particles of magnetite. Thereafter, an aqueous solution of a surfactant solubilized by adding an equal amount of an aqueous alkali solution is added to the reaction solution, and the surfactant is adsorbed on the surface of the fine particles by heat treatment. After cooling, an acid is added dropwise to the reaction solution to obtain an acidic aqueous solution. Repeat washing of the precipitate with water to remove excess surfactant and salts. The precipitate is dried under reduced pressure to obtain a powder.
Next, the obtained powder is mixed with an intended polymerizable dispersion medium to obtain a polymerizable magnetic fluid. When obtaining a purified polymerizable magnetic fluid, the magnetic fine particles having poor dispersibility may be removed by centrifugation.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 (1) Synthesis of Br (CH ₂ ) ₁₀ COOCH ₃ Br (CH ₂ ) ₁₀ COOH 20 was placed in a 1 l Erlenmeyer flask.
0 g, 242 g of methanol, p-CH ₃ C ₆ H ₄ SO ₃ H
· H ₂ O 2.00g, put toluene 400 ml, and heating was continued under reflux for 10 hours. Water from the reaction solution
After removing with O ₄ , toluene and methanol were distilled off under reduced pressure. The product was purified by distillation under reduced pressure to obtain 198 g of a colorless liquid (boiling point 125 ° C./0.3 mmHg).

(2) H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₀ CO
Synthesis of OH H (C ₂ H ₄ O) ₃ H was added to a 300 ml two-necked round bottom flask.
40.24 g, 6.67 g of Na, 4.98 g of KI, and 100 ml of toluene were added and heated under reflux for 9 hours. Na
After confirming that all of them have been consumed, Br (CH ₂ ) ₁₀
A solution of 41.9 g of COOCH _{3 in} 50 ml of toluene was added to 7
It was dropped over time. Thereafter, the reaction was terminated by continuing heating and refluxing for another 10 hours.

After distilling off toluene from the above reaction solution under reduced pressure, 10 g of NaOH and 100 ml of water were added, and the mixture was heated under reflux for 18 hours. After heating under reflux, methanol produced by the reaction was distilled off under reduced pressure. Aqueous hydrochloric acid was added until the pH reached 1. NaCl was added to the reaction until it was saturated. The reaction solution was extracted with chloroform, and the obtained organic phase was washed with saturated saline. After the chloroform was removed under reduced pressure, the raw material H (C ₂ H ₄ O) ₃ H was removed by vacuum distillation. As a crude product, 35.8 g of a brown liquid, which was a residue, was obtained.

20 g of the above crude product was purified by a column. A 11 cm diameter column was packed with Wakogel C-200 to a height of 8 cm. The developing solvent is chloroform /
Methanol (99/1) was used. By-product CH ₂ =
After CH (CH ₂ ) ₈ COOH was eluted, the developing solvent was changed to chloroform / methanol (97/3) to elute the desired purified product. 1 pale brown liquid as purified product
2 g were obtained.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 1.0 to 1.8 ppm
_{(M; 19H, CH 3,} CH 2), 2.34ppm (t;
_{2H, CH 2 COO), 3.3~3.8ppm} (m; 1
2H, CH ₂ OCH _2).

IR: 1110, 1460, 1710, 1
735, 2840, 2920 cm-1 From these analysis results, the purified product was found to be H (C ₂ H ₄ O) ₃ (C
It was confirmed to have a structure of H ₂ ) ₁₀ COOH.

Example 2 CH ₃ O (C ₂ H ₄ O) ₃ (C
Synthesis of H ₂ ) ₁₀ COOH Instead of H (C ₂ H ₄ O) ₃ H as a raw material, CH ₃ O (C ₂
Example 1 except that 79.18 g of H ₄ O) ₃ H was used, and tetrahydrofuran was used instead of toluene as a solvent.
Synthesized according to the following procedure. As a crude product, 40.5 g of a brown liquid as a residue was obtained. 15 g of the above crude product was purified by a column. As a purified product, 5.0 g of a light brown liquid was obtained.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 1.1 to 1.8 ppm
_{(M; 16H, CH 2)} , 2.34ppm (t; 2H,
_{CH 2 COO), 3.2~3.8ppm (m} ; 17H,
_{CH 3 O, CH 2 OCH 2} ).

IR: 1110, 1465, 1710, 1
735, 2860, 2930 cm-1 From these analysis results, the purified product was CH ₃ O (C ₂ H ₄ O) ₃
It was confirmed to have a structure of (CH ₂ ) ₁₀ COOH.

Example 3 C ₁₂ H ₂₅ O (C ₂ H ₄ O) ₂₅ (C
Synthesis of H ₂ ) ₁₀ COOH Instead of H (C ₂ H ₄ O) ₃ H as a raw material, C ₁₂ H ₂₅ O
(C ₂ H ₄₀ ) Synthesized according to Example 1 except that 390 g of ₂₅ H was used. As a crude product, 420 g of a brown liquid, which is a residue, was obtained. 20 g of the above crude product was purified by a column. 5g of pale brown liquid as purified product
Obtained.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 0.89 ppm (t; 3
_{H, CH 3), 1.1~1.8ppm (} m; 36H, C
_{H 2), 2.34ppm (t;} 2H, CH 2 COO),
_{3.3~3.8ppm (m; 104H, CH 2} OC
H _2).

IR: 1110, 1460, 1710, 1
735, 2840, 2920 cm -1 From these analysis results, the purified product was found to be C ₁₂ H ₂₅ O (C ₂ H
₄ O) have a ₂₅ (CH ₂₎ a ₁₀ COOH structure was confirmed.

Example 4 (1) Synthesis of Br (CH ₂ ) ₁₁ COOCH ₃ Instead of Br (CH ₂ ) ₁₀ COOH as a raw material, Br
Synthesized according to Example 1 except that (CH ₂ ) ₁₁ COOH was used. 193 g of a colorless liquid was obtained as the product (boiling point 133 ° C./0.5 mmHg).

(2) H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₁ CO
Synthesis of OCH ₃ Instead of Br (CH ₂ ) ₁₀ COOCH ₃ which is a raw material, Br
It was synthesized according to Example 1 except that 43.7 g of (CH ₂ ) ₁₁ COOCH ₃ was used. As a crude product, 35.7 g of a brownish liquid as a residue was obtained.

20 g of the above crude product was purified by a column. A 11 cm diameter column was packed with Wakogel C-200 to a height of 8 cm. The developing solvent is chloroform /
Methanol (99/1) was used. By-product CH ₂ =
After CH (CH ₂ ) ₉ COOH was eluted, the developing solvent was changed to chloroform / methanol (97/3) to elute the desired purified product. 1 pale brown liquid as purified product
0 g was obtained.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 1.0 to 1.8 ppm
_{(M; 21H, CH 3,} CH 2), 2.34ppm (t;
_{2H, CH 2 COO), 3.3~3.8ppm} (m; 1
2H, CH ₂ OCH _2).

IR: 1110, 1460, 1710, 1
735, 2840, 2920 cm-1 From these analysis results, the purified product was found to be H (C ₂ H ₄ O) ₃ (C
It was confirmed to have a structure of H ₂ ) ₁₁ COOH.

Example 5 (1) Synthesis of Br (CH ₂ ) ₁₂ COOCH ₃ Instead of Br (CH ₂ ) ₁₀ COOH as a raw material, Br
Synthesized according to Example 1 except that (CH ₂ ) ₁₂ COOH was used. 190 g of a colorless liquid was obtained as the product (boiling point 142 ° C./0.2 mmHg).

(2) H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₂ CO
Synthesis of OH Instead of Br (CH ₂ ) ₁₀ COOCH ₃ which is a raw material, Br
The synthesis was carried out according to Example 1 except that 45.8 g of (CH ₂ ) ₁₂ COOCH ₃ was used. As a crude product, 33.7 g of a brown liquid, which was a residue, was obtained.

20 g of the above crude product was purified by a column. A 11 cm diameter column was packed with Wakogel C-200 to a height of 8 cm. The developing solvent is chloroform /
Methanol (99/1) was used. By-product CH ₂ =
After CH (CH ₂ ) ₁₀ COOH was eluted, the developing solvent was changed to chloroform / methanol (97/3) to elute the desired purified product. 9 g of a light brown liquid was obtained as a purified product.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 1.0 to 1.8 ppm
_{(M; 23H, CH 3,} CH 2), 2.34ppm (t;
_{2H, CH 2 COO), 3.3~3.8ppm} (m; 1
2H, CH ₂ OCH _2).

IR: 1110, 1460, 1710, 1
735, 2840, 2920 cm-1 From these analysis results, the purified product was found to be H (C ₂ H ₄ O) ₃ (C
It was confirmed to have a structure of H ₂ ) ₁₂ COOH.

Application Example 1 H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₀ C
Preparation of Fe ₃ SO ₄ Polymerizable Magnetic Fluid Using OOH as a Surfactant FeSO ₄ .7H ₂ O and Fe ₂ (SO ₄ ) ₃ under nitrogen
50 ml of a 1 molar aqueous solution of nH ₂ O was mixed, and the pH was adjusted to 11.5 while stirring a 6N aqueous solution of NaOH.
It dripped until it became. This was heated at 70 ° C. for 5 minutes to produce a magnetite colloid. On the other hand, H (C ₂ H
_{4 O) 3 (CH 2)} 10 COOH 4.17g of weighed into another vessel under nitrogen, to which aqueous NaOH 3N 4.3
7 ml and 50 ml of water were added to obtain a homogeneous solution. The above surfactant was added to the magnetite colloid prepared above, and the mixture was kept at 80 ° C. for 30 minutes with stirring. After cooling, a 1N aqueous hydrochloric acid solution was added to the reaction solution to adjust the pH to 5.5, and the colloid was aggregated. The aggregate was washed with water repeatedly to remove the electrolyte, and finally the solid obtained by vacuum filtration was dried at 90 ° C. under reduced pressure for 10 hours. After allowing to cool to room temperature, it was taken out of the dryer. The obtained crude product weighed 12.5 g,
It was a black non-viscous powder.

0.6 g of the obtained crude product was dispersed in 1.4 g of various polymerizable dispersion media shown in Table 1, and
The precipitate was removed from the supernatant by centrifugation under a centrifugal force of 00 G for 20 minutes. Table 1 summarizes the formation of precipitates and the change over time in the state of the solution after storage at room temperature for 3 months. In addition, each symbol in Tables 1-3 and 5 has the meaning shown below.

：: No precipitate was formed even after storage at room temperature for 3 months. ×: A precipitate was formed during storage for 3 months at room temperature. A: Storage after storage for 3 months. Z: room temperature, solidified during storage for 3 months. Magnetic fluid using linear aliphatic carboxylic acid of the present invention as a surfactant for 3 months. After that, no precipitation was observed, and the solid remained without liquidation. It was confirmed that the polymerizable magnetic fluid had high storage stability.

[0055]

[Table 1]

Application Example 2 C ₁₂ H ₂₅ O (C ₂ H ₄ O) ₂₅ (C
Preparation of Fe ₃ SO ₄ -based polymerizable magnetic fluid using H ₂ ) ₁₀ COOH as a surfactant Instead of H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₀ COOH as a raw material, C ₁₂ H ₂₅ O (C ₂ H ₄ O) ₂₅ (CH 2) ₁₀ COOH
Prepared according to Application Example 1 except that 19.3 g was used. The obtained crude product weighed 26.5 g and was a black viscous powder.

0.6 g of the obtained crude product was dispersed in 1.4 g of various polymerizable dispersion media shown in Table 2, and this dispersion was dispersed in 80 g
The precipitate was removed from the supernatant by centrifugation under a centrifugal force of 00 G for 20 minutes. Table 2 summarizes the formation of precipitates and the change over time in the state of the solution after storage for 3 months at room temperature. Even in these magnetic fluids, no precipitate was found even after storage for 3 months, and the liquid remained liquid without solidification. It was confirmed that the polymerizable magnetic fluid had high storage stability.

[0058]

[Table 2]

Application Example 3 H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₂ C
Is the preparation raw materials of the surfactant and the Fe ₃ SO ₄ polymerizable magnetic fluid _{OOH H (C 2 H 4 O} ) 3 (CH 2) 10 instead of H of _{COOH (C 2 H 4 O)} 3 (CH ₂ ) 4.50 g of ₁₂ COOH
Was prepared according to Application Example 1 except that was used. The obtained crude product weighed 12.3 g and was a black viscous powder.

0.6 g of the obtained crude product was dispersed in 1.4 g of various polymerizable dispersion media shown in Table 3, and
The precipitate was removed from the supernatant by centrifugation under a centrifugal force of 00 G for 20 minutes. Table 3 summarizes the formation of precipitates and the change over time in the state of the solution after storage at room temperature for 3 months. Even in these magnetic fluids, no precipitate was found even after storage for 3 months, and the liquid remained liquid without solidification. It was confirmed that the polymerizable magnetic fluid had high storage stability.

[0061]

[Table 3]

Application Example 4 Photopolymerization of Polymerizable Magnetic Fluid In the same manner as in Application Examples 1 to 3, 0.4 g of a polymerizable magnetic fluid obtained from magnetite, a surfactant and a polymerizable dispersion medium shown in Table 4 was added. Then, a photopolymerization initiator (photosensitizer 0.001 g, photopolymerization accelerator 0.001 g) shown in Table 4 was added, and a part of this solution was sandwiched between glass plates. When the illuminance on the glass surface is 5
It was irradiated with light of 000 lx for the time shown in Table 4. The symbols in Table 4 have the following meanings.

：: The polymerizable magnetic fluid was solidified. X: The polymerizable magnetic fluid was not completely solidified and had fluidity. Polymerizable magnetic fluid obtained by using the linear fatty acid carboxylic acid of the present invention. All the fluid solidified and the glass plate stopped moving.

[0064]

[Table 4]

Comparative Example 1 Preparation of Fe ₃ SO ₄ Polymerizable Magnetic Fluid Using Linoleic Acid as Surfactant Linoleic acid was used instead of H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₀ COOH as a raw material. 8.8 g of 3N NaOH aqueous solution was added to 3 g.
It was prepared according to Application Example 1 except that a solution to which ml was added was used. The obtained crude product weighed 14.8 g and was a black viscous powder.

0.6 g of the obtained crude product was dispersed in 1.4 g of various polymerizable dispersion media shown in Table 5, and this dispersion was dispersed in 80 g of a dispersion medium.
The precipitate was removed from the supernatant by centrifugation under a centrifugal force of 00 G for 20 minutes. Table 5 summarizes the formation of precipitates and the change over time in the state of the solution after storage at room temperature for 3 months. The magnetic fluid does not change with time in a monofunctional monomer-based polymerizable dispersion medium, but precipitates and solidifies in a polyfunctional monomer-based polymerizable dispersion medium, and clearly shows a change with time. It was confirmed that.

[0067]

[Table 5]

Comparative Example 2 H (C ₂ H ₄ O) ₂ (CH ₂ ) ₈ C
Is the preparation raw materials of the surfactant and the Fe ₃ SO ₄ polymerizable magnetic fluid _{OOH H (C 2 H 4 O} ) 3 (CH 2) 10 COOH instead H of _{(C 2 H 4 O) 2} (CH ₂ ) A magnetic fluid was prepared in the same manner as in Application Example 1 except that ₈ COOH was used. Room temperature, 3
Table 6 summarizes the formation of precipitates and the change over time in the state of the liquid after storage for months. The magnetic fluid does not change with time in a monofunctional monomer (polymerizable dispersion medium),
It was confirmed that a precipitate was formed and solidified in the polyfunctional monomer (polymerizable dispersion medium), and clearly changed with time.

[0069]

[Table 6]

The above linear aliphatic carboxylic acid used in this comparative example was synthesized as follows.

(1) Synthesis of Br (CH ₂ ) ₈ COOCH ₃ Instead of Br (CH ₂ ) ₁₀ COOH as a raw material, Br
Synthesized according to Example 1 except that (CH ₂ ) ₈ COOH was used. 193 g of a colorless liquid was obtained as the product (boiling point 108 ° C./0.8 mmHg).

(2) H (C ₂ H ₄ O) ₂ (CH ₂ ) ₈ CO
It is a synthetic raw material of _{OCH 3 H (C 2 H 4} O) 3 H instead H (C ₂ H in
₄ O) using _{2 H 27.0g, Br (CH 2} ) 10 COO
Br (CH ₂ ) ₈ COOCH ₃ 37.7 instead of CH ₃
Synthesized according to Example 1 except that g was used. As a crude product, 20.0 g of a brownish liquid as a residue was obtained.

15 g of the above crude product was purified by a column. As a purified product, 10 g of a light brown liquid was obtained.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 1.0 to 1.8 ppm
_{(M; 15H, CH 3,} CH 2), 2.34ppm (t;
_{2H, CH 2 COO), 3.3~3.8ppm} (m; 8
H, CH ₂ OCH _2).

IR: 1110, 1460, 1710, 1
735, 2840, 2920 cm -1 From these analysis results, the purified product was identified as H (C ₂ H ₄ O) ₂ (C
It was confirmed to have a structure of H ₂ ) ₈ COOCH ₃ .

Comparative Example 3 HO (C ₂ H ₄ O) ₂ (CH ₂ ) ₁₀
Preparation of Fe ₃ SO ₄ Polymerizable Magnetic Fluid Using COOH as Surfactant Instead of H (C ₂ H ₄ O) ₃ (CH ₂ ) ₁₀ COOH as a raw material, HO (C ₂ H ₄ O) ₂ (CH ₂ ) A magnetic fluid was prepared in the same manner as in Application Example 1 except that ₁₀ COOH was used.
The magnetic particles did not disperse in any of the polymerizable dispersion media, and no magnetic fluid was obtained. The linear aliphatic carboxylic acid used in this comparative example was synthesized as follows.

HO (C ₂ H ₄ O) ₂ H was replaced with 340 g of H (C ₂ H ₄ O) ₃ H, and synthesis was carried out according to Example 1 except that toluene was not used. As a crude product, 53.3 g of a brown liquid as a residue was obtained.

43 g of the above crude product was added to 43 m of methanol.
and left at −20 ° C. overnight. The precipitated crystals were filtered and dried to obtain 7.2 g of a solid as a purified product.

1H-NMR of the purified product (CDCl ₃ , T
MS is used as a reference (0.00 ppm). ) And IR analysis gave the following results.

1H-NMR: 1.1 to 1.8 ppm
_{(M; 18H, CH 2)} , 2.34ppm (t; 2H,
_{CH 2 COO), 3.3~3.9ppm (m} ; 11H,
CH ₂ OCH _2, HOC).

IR: 1110, 1465, 1720, 1
735, 2860, 2910, 3450 cm-1 From these analysis results, the purified product is HO (C ₂ H ₄ O)
It was confirmed to have a structure of ₂ (CH ₂ ) ₁₀ COOH.

[0083]

The present invention comprises a linear aliphatic carboxylic acid.
In the polymerizable magnetic fluid prepared using the surfactant for producing a polymerizable magnetic fluid described above, the magnetic fine particles are dispersed in a stable state without generating a precipitate during storage. Further, during storage, no polymerization occurs, and the resin is cured only at the time of polymerization.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 1/44 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A compound of the general formula (However, R represents an alkyl group having 1 to 12 carbon atoms, and n represents 1 to
An integer of 25, m is composed of a linear aliphatic carboxylic acid represented by each show) an integer of 10 to 12 polymerizable ferrofluid
Surfactants for manufacturing .