KR100301608B1 - Anhydrous Electrorheological Fluid and Preparation thereof - Google Patents

Abstract

The present invention relates to anhydrous electrorheological fluids used for effective control of ER devices such as shock absorbers, dampers, clutches, engine mounts and valves. Specifically, the present invention is characterized in that the high yield stress, low current density, wear resistance, dispersibility, fast response characterized in that the chitosan phosphate particles coated with an organic amine compound dispersed by the base fluid The present invention relates to an anhydrous electrorheological fluid having excellent electrical, rheological, physicochemical and mechanical properties such as stability, high temperature stability, and biodegradability, and a method of preparing the same.

Description

Anhydrous electrorheological fluid and preparation method thereof {Anhydrous Electrorheological Fluid and Preparation etc}

The present invention relates to anhydrous electrorheological fluids used for effective control of ER devices such as shock absorbers, dampers, clutches, engine mounts and valves. Specifically, the present invention is characterized in that the high yield stress, low current density, wear resistance, dispersibility characterized in that the fine particles of chitosan phosphate coated with an organic amine compound prepared by dispersing in a base fluid (base fluid) The present invention relates to an anhydrous electrorheological fluid having excellent electrical, rheological, physicochemical and mechanical properties, such as fast response, high temperature stability, and biodegradability, and a method of manufacturing the same.

An electrorheological fluid is a colloidal liquid in which a rheological material, which is a fine particle such as ceramic and polymer material, is polarized to insulating fluids such as synthetic oil, mineral oil and vegetable oil, and is very fast (10,000 to 1 / 10,000 seconds under an electric field). It shows the properties of the Bingham fluid, which is a solid phase, but has the property of reducing to the original liquid phase when the electric field is removed. This is known because the polar particles dispersed in the insulating fluid under the electric field form a chain or fiber structure connecting the electrodes.

Conventional electrorheological fluids include polar solvents such as rheology materials such as starch (US Pat. No. 2,417,508), silica (US Pat. No. 3,407,507), zeolite (US Pat. No. 4,702,855), such as corn and potato, and water. And an aqueous electrorheological fluid composed of a composition of an insulating fluid, and have many problems such as unstable electric rheological properties due to precipitation of rheological materials, evaporation of polar solvents such as moisture, and corrosion and wear in the apparatus.

In order to solve the above problems with the conventional aqueous electrofluidic fluid, a number of anhydrous electrophilic fluids have been developed. U.S. Patent Nos. 4,992,192 and 5,336,423 were prepared by dispersing a polymer salt by reacting a copolymer of styrene, maleic acid and alkali in base oil, and U. S. Patent Application A8900825.6 and In 9313408.8, polyaniline was dispersed as a rheological material, and in US Pat. No. 5,268,118, polyurethane was dispersed in base oil to prepare an electrorheological fluid.

In recent years, the instability of the electrorheological properties due to the evaporation of water and the corrosion resistance and abrasion resistance of the device have been improved, compared to the water-based electrorheological fluid activated by water, which is a conventional technique. The rheological effects of stability are still not satisfactory. In particular, the rheological materials composed of synthetic polymers are mostly caused by the phenomenon of sticking to the electrode at high temperature, thereby causing a problem in quick response, thereby reducing the electrorheological effect.

The present inventors have intensively studied these problems with the above-mentioned electro-fluidic fluids. As a result, the anhydrous electro-fluidic fluid containing fine particles of chitosan phosphate coated with an organic amine compound has a high yield stress and a low yield. It has excellent performances such as current density, dispersion, wear resistance, fast response and high temperature stability, so it can be used in various fields such as automobile shock absorber, clutch, damper system and engine mount, and electronic system such as printer, copier and washing machine. It was found that the present invention has been completed, and in particular, it has been found to have environmentally friendly biodegradability, which cannot be seen in the prior art.

It is an object of the present invention to provide an anhydrous electrorheological fluid having a superior performance such as stability, dispersibility, abrasion resistance, fast response and biodegradability of an electrorheological effect at a wide range of temperatures and a process for producing the fluid.

The composition of the electrorheological fluid according to the present invention consists of 10-50 vol% (vol%) of chitosan phosphate powder coated with an organic amine compound as a rheological material and 50-90 vol% (vol%) of base oil.

Hereinafter, the present invention will be described in detail.

Chitosan phosphate used as a rheological material is a natural biopolymer and synthesized by phosphorylation of chitosan produced by deacetylation of chitin obtained from shells of crabs, shrimp and the like. Phosphorylation of chitosan is carried out by a phosphoric acid compound and a nitrogen compound. The phosphoric acid compound used herein is ammonium phosphate such as phosphoric acid, ammonium bisulfate, and diammonium hydrogen phosphate, and the nitrogen compound is urea, di or triethanolamine, melamine, etc. This is used.

In detail, the preparation method was performed by adding 70-150 g of chitosan to 1 L of an aqueous solution of 85% phosphoric acid or ammonium phosphate and 1-4 mol of urea, and reacting for 0.5-3 hours at a reaction temperature of 30-60 ° C. The filtrate was then heat-treated at 120-170 ° C. for 0.5-3 hours. Then rinse with water and dry until no phosphoric acid is detected. The phosphorus content of the synthesized chitosan phosphate is 3-15 wt% (wt%), the nitrogen content is 3.0-8.0 wt%, and the particle size is in the range of 1-50 μm, but 5-30 μm is suitable. If the particle size of the chitosan phosphate is less than 1 μm, it exhibits a low electrorheological effect. If the particle size exceeds 50 μm, it results in an unstable electrorheological effect due to precipitation.

The chitosan phosphate synthesized in the present invention exhibits excellent electrorheological effect and abrasion resistance, but it is not easy to disperse with the base oil as a result of the basic experiment, and the chitosan phosphate was coated with an organic amine compound to improve the dispersibility. .

The organic amine compound, which is a film coating agent of chitosan phosphate, was used to enhance the dispersing effect, and the alkyl group thereof is butyl, hexyl, octyl and octadecyl, and has 4 to 20 carbon atoms in this range. Dilution is easy. In addition, there is a polybutenyl succinic imide or polystyrenyl succinic imide compound, and a suitable amount of chitosan phosphate is added to an organic solvent diluted 0.1 to 2.0 wt% of acetone or alcohol to room temperature. Stir in a mixer for 0.5-2 hours and then dry. In this case, the coated chitosan phosphate has a thin film thickness of 0.5-5 μm. Chitosan phosphate having a thin film thickness of less than 0.5 μm is poor in dispersibility and well dispersed when it is larger than 5 μm, but the electric rheological effect and wear resistance are reduced.

Through the above manufacturing process, chitosan phosphate, which is a rheological material, and chitosan phosphate coated with an organic amine compound are synthesized, and the amount of chitosan phosphate is in the range of 10-50% by volume based on the volume weight of the total electrophoretic fluid. Suitable. If the content of chitosan phosphate coated with the organic amine compound is less than 10% by volume, it is easy to control the system, but the effect of electro-fluidism is low. On the contrary, when it exceeds 50% by volume, it is not easy to control the system due to the high initial viscosity. .

Mineral oil, synthetic oil, vegetable oil, etc. are used as base oil. Examples of synthetic oils include silicone oils, diester oils, poly-alphaolefin oils, and fluoro synthetic hydrocarbon-based synthetic oils, and vegetable oils include soybean oil, corn oil, rapeseed oil, and the like. However, among these, the use of synthetic oil is suitable for special fields such as low temperature and high temperature. This is because synthetic oils have excellent low and high temperature stability compared to vegetable oils and mineral oils. The volume weight of the base oil is suitably in the range of 50-90% by volume, based on the volume weight of the total electrophoretic fluid.

Hereinafter, the manufacturing process of the anhydrous electrorheological fluid of the present invention will be described.

First, chitosan as a raw material was subjected to phosphorylation at a reaction temperature of 30-60 ° C. in a certain molar phosphoric acid or an aqueous solution of ammonium phosphate and urea, followed by heat treatment at 120-170 ° C. for a period of time to synthesize chitosan phosphate. Thereafter, a predetermined proportion of the organic amine compound having a carbon number in the range of 4-20 is dried in a solution dissolved in an organic solvent after coating at room temperature for a certain time. Anhydrous electrorheological fluid is prepared by putting chitosan phosphate powder coated with an organic amine compound and a base oil in a ball mill container at a predetermined ratio, and mixing the mixture for 0.5 to 3 hours at a temperature of 50 to 80 ° C.

Anhydrous electrorheological fluids according to the present invention have superior physical properties such as stability, dispersibility, wear resistance, fast response and biodegradability of electrorheological effects at a wide range of temperatures compared to conventional electrorheological fluids. In addition to devices, dampers, clutches and engine mounts, it is suitable as a multi-purpose electrophoretic fluid such as electronic products such as printers, washing machines and copiers.

The present invention will be described in more detail with reference to the following Examples.

In the embodiment, the electrorheological properties of the electrorheological fluid of the present invention were measured using a Physica Rheomether, Germany tester, the wear resistance of the American standard ASTM D2266, the corrosion test of the same standard ASTM D2451, Biodegradability was assessed by the CEL-L-33-T-82 test method and compared with conventional commercially available rheological fluid products.

<Example 1>

Electrorheological Fluid Composed of a Composition of Chitosan Phosphate

100 g of chitosan powder (particle size 20 µm) was added to 1 L of an aqueous solution of 1-4 mol of 85% phosphoric acid and 4 mol of urea, respectively, and reacted at a reaction temperature of 40 ° C for 1 hour. After the reaction, the reaction was heat-treated at 150 ° C. for 1 hour to synthesize chitosan phosphate, and then, washed with water until no phosphoric acid was detected and re-dried. And chitosan phosphate was synthesized by the same method using an aqueous solution of 3 moles of ammonium deuterium phosphate and 4 moles of urea, and the comparison results are shown in Table 1. As described in Table 1 below, 30 vol% of chitosan phosphate powder synthesized in each phosphorylation reaction and 70 vol% of silicone oil having a viscosity of 30 cst were placed in a ball mill and mixed at 60 ° C. for 1 hour to prepare an electrorheological fluid. Physical properties of are shown in Table 1.

Electrorheological fluids One 2 3 4 5 6 <Composition ratio> Chitosan Phosphate (% by volume) 0 30 30 30 30 30 Phosphoric Acid (Mall) 0 One 2 3 4 Element (mall) 0 4 4 4 4 4 Ammonium Deuterium Phosphate (mol) 3 Silicone oil (% by volume) 100 70 70 70 70 70 <Water castle> Yield Stress (Pa, 25 ℃, 3KV / mm) 0.28 985 1526 1342 1163 1248 Abrasion Resistance (mm) 0.74 0.63 0.58 0.55 0.54 0.56 Biodegradability (%) 35 72 71 69 65 70

As shown in Table 1, the yield stress increases with increasing amount of phosphoric acid, but decreases above 2 moles, but abrasion resistance is on the increase. The decrease in yield stress when the amount of phosphoric acid is more than 2 moles is due to the decrease in the strength of the chain structure formed under the electric field due to the increase in the current density of the chitosan phosphate. In addition, since the formation of a thin film of iron phosphide (FePO ₄ ) is easy under the lubrication contact point, the wear resistance increases as the amount of phosphoric acid increases.

<Example 2>

An electrorheological fluid consisting of a composition of chitosan phosphate coated with an organic amine compound

50 g of chitosan phosphate synthesized from 2 moles of phosphoric acid and 4 moles of urea in Example 1 was added to 300 ml of a solution in which octadecylamine was dissolved in acetone within a range of 0.1 to 2.0% by weight, and stirred at room temperature for 1 hour, followed by drying. The octadecylamine-coated chitosan phosphate was prepared, and chitosan phosphate coated with a thickness of 1 μm was prepared in a 0.5% by weight solution of polybutenylsuccinimide, and their physical properties are shown in Table 2. Indicated.

Electrorheological fluids 3 7 8 9 10 <Composition ratio> Chitosan phosphate coated with organic amine compound (% by volume) 30 30 30 30 30 Octadecylamine (wt%) 0 0.5 1.0 1.5 Polybutenyl Succinimide (wt%) 0.5 Silicone oil (% by volume) 70 70 70 70 70 <Property> Yield Stress (Pa, 3kV / mm, 25 ℃) 1526 1280 1138 1064 1253 Abrasion Resistance (mm) 0.58 0.60 0.63 0.65 0.57 Dispersibility (Pa, 3 kV / mm, 25 ℃, 30 days) 745 1268 1112 1052 1218

In Example 2, the yield stress and abrasion resistance decrease as the amount of octadecylamine increases, because the polarity decreases as the electrical conductivity decreases, and since the formation of iron phosphide, a thin film structure formed on the lubricating contact point, is not easy, Is on the decline. In the case of the fluid No. 3 of the above embodiment, since the organic amine compound is not coated, the initial electrorheological effect is excellent, but the electrorheological effect after being left for 30 days shows a low value. Therefore, it can be seen that the chitosan phosphate coated with the organic amine compound has excellent dispersibility.

<Example 3>

Preparation of Electro-Rheological Fluids According to Types of Base Oils

Mineral oil, corn oil and diester synthetic oils were used as base oils instead of silicone oils in the composition of the electrorheological fluid No. 7 in Example 2. The results are shown in Table 3.

Electrorheological fluids 7 11 12 13 <Composition ratio> Chitosan phosphate coated with octadecylamine (% by volume) 30 30 30 30 Silicone oil (% by volume) 70 Mineral oil (% by volume) 70 Corn oil (% by volume) 70 Diester oil (% by volume) 70 <Water castle> Yield Stress (Pa, 3kV / mm, 25 ℃) 1280 1295 1322 1306 Biodegradability (%) 71 72 98 95

As shown in Table 3, the electrorheological effect according to the type of base oil shows almost similar results, but there are many differences in biodegradability.

<Example 4>

Preparation of Electro-Rheological Fluids According to Kinds of Electro-Rheological Materials

30 vol% of silica gel and polyaniline powder and 70 vol% of silicone oil, which are well known as a rheological material, were then stirred in a mixer at a temperature of 60 ° C. for 1 hour to prepare an electrorheological fluid, and these were prepared in Example 2 of the present invention. The electrorheological fluids and physical properties were compared and the results are shown in Table 4.

Electrorheological fluids 7 14 15 Composition ratio (% by volume) Chitosan phosphate coated with octadecylamine 30 Silica gel (containing 5.0 wt% of water) 30 Polyaniline 30 Silicone oil 70 70 70 <Water castle> Yield Stress (Pa, 3kV / mm, 25 ℃) 1280 485 1035 Abrasion Resistance (mm) 0.58 1.32 0.68 Biodegradability (%) 71 25 34 causticity One 2 One

As shown in Table 4, the fluid No. 7 in the Example has excellent yield stress, wear resistance, and biodegradability as compared with the fluids of Comparative Examples No. 14 and 15 having compositions of polyaniline, silica gel, and the like, which are conventional anhydrous electrorheological materials. It can be seen.

Comparative Example

In addition, US products (comparative product 1; Lubrizol Co., composition: silicone oil and polyaniline) and German products (comparative product 2; Bayer Co., composition: silicone oil) have excellent performance among commercially available anhydrous fluids. And polyurethane) were compared with the present invention and the results are shown in Table 5 below.

Properties Invention Product Comparative product 1 Comparative product 2 1. Yield stress (Pa, 3kV / mm, 25 ℃) 1350 1035 1280 2.wear resistance (mm) 0.58 0.68 0.71 3.biodegradability (%) 71 34 35 4. Dispersibility (Pa, 3kV / mm, 25 ℃, 30 days) 1268 780 1225 5. Corrosion One One One 6.High temperature stability (Pa, 3kV / mm) 40 ℃ 1615 1356 1843 80 ℃ 2180 1102 1358 100 ℃ 2864 653 945

As shown in Table 5, it can be seen that the anhydrous electrorheological fluid of the present invention has superior properties such as physicochemical, mechanical and electrorheological properties such as high temperature stability, abrasion resistance, biodegradability, and dispersibility. .

The anhydrous electrorheological fluid of the present invention exhibits excellent performances such as high yield stress, low current density, dispersibility, wear resistance, fast response, high temperature stability, and the like, such as automobile shock absorbers, clutches, dampers, engine mounts, and the like. It can be used in various fields such as electronic systems such as printers, copiers and washing machines.

Claims (9)

Anhydrous electrolying fluid consisting of 10-50% by volume of chitosan phosphate powder coated with an organic amine compound and 50-90% by volume of base oil. The anhydrous electrophilic fluid of claim 1, wherein the organic amine compound is selected from the group consisting of alkylamine compounds having 4 to 20 carbon atoms, polybutenylsuccinimide, polystyrylsuccinimide, and the like. The anhydrous electrophilic fluid of claim 2, wherein the alkylamine compound is selected from butylamine, hexylamine, octylamine and octadecyl amine. The anhydrous electrophilic fluid according to claim 1, wherein the chitosan phosphate has a phosphorus content of 3-15 wt%, a nitrogen content of 3.0-8.0 wt%, and a particle size of 1-50 μm. 5. Anhydrous electrophilic fluid according to claim 4, wherein said particle size is 5-30 [mu] m. The method of claim 1, wherein the chitosan phosphate is selected from chitosan by using 1-4 moles of phosphoric acid compound selected from phosphoric acid, ammonium bisulfate and diammonium hydrogen phosphate and nitrogen compound 1-4 mole selected from urea, di or triethanolamine and melamine. Anhydrous electrorheological fluid prepared by phosphorylation reaction. The anhydrous electrophilic fluid according to claim 1, wherein the chitosan phosphate coated with the organic amine compound has a film thickness of 0.5 to 5 µm. 2. The anhydrous electrorheological fluid of claim 1, wherein the base oil is selected from mineral oil, synthetic oil and vegetable oil. The chitosan phosphate prepared by phosphorylation of chitosan in an aqueous solution of a phosphoric acid compound and a nitrogen compound at a reaction temperature of 30 to 60 ° C. and a reaction time of 0.5 to 3 hours, and then heat-treated at 120 to 170 ° C. for 0.5 to 3 hours was used as an organic amine compound. Anhydrous electric oil according to claim 1, comprising mixing 10-50% by volume of chitosan phosphate coated with an organic amine compound and 50-90% by volume of base oil at a temperature of 50-80 ° C. after coating. Method for producing a modified fluid.