JP2920196B2 - Electric field responsive fluid - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to fluids that solidify or increase viscosity upon application of an electric field, and more particularly, to particles and electrical insulation that suspends or disperses the particles. The present invention relates to an electric field responsive liquid having a Winslow effect, comprising an ionic liquid.

[Conventional technology]

When a liquid in which solid fine particles are dispersed in an electrically insulating medium is used and an external electric field is applied thereto, a phenomenon that the viscosity of the liquid is significantly increased is observed. This phenomenon is known as a Winslow effect. This phenomenon is expected to be applied to clutch shock absorbers (dampers), hydraulic control devices, printers, vibrating elements, and the like, and some of them have been put to practical use.

Several proposals have been made to improve liquids exhibiting such a phenomenon (electrically responsive fluid). Representative examples include the use of hydrophilic powders such as starch, flour, gypsum, carbon, and limestone in mineral oil, The viscosity is increased by applying an electric field to a specific fluid suspended in an insulating oil such as olive oil or transformer oil (USP2417850), using a strongly acidic cation exchange resin or a strongly basic ion exchange resin as particles. That is, a polymer having a dissociable anionic group or cationic group is used (Japanese Patent Publication No. 52-30273).
Use is made by dispersing dielectric fine particles in which conductive particles are coated with an electrically insulating thin film in an electrically insulating oily medium (Japanese Patent Application Laid-Open No. 64-6093). And a polymer containing a quaternary ammonium salt having an alkyl group having 4 to 30 carbon atoms as particles (Japanese Patent Publication No. Sho 60-97694). However, these electric field-responsive liquids have the following problems.

That is, in the above, since the electric field responsive fluid containing particles of starch, flour or the like has a small obtained shearing force, it is necessary to increase the size of the apparatus or to increase the applied voltage to be put to practical use. Problem.

In the above, a relatively large shearing force is obtained in the fluid using the ion exchange resin, but since the specific gravity of the particles is relatively high, a liquid compound containing a halogen element, which is not preferable from a safety point of view, is used as the insulating liquid. Otherwise, sedimentation of the particles cannot be prevented.

In the above, particles in which conductive particles are coated with an insulating layer are used. When a metal such as aluminum is used as the conductive particles, the specific gravity of the particles becomes extremely large, and the particles settle rapidly. In addition, such a fluid does not always provide a large shear force, and when an electric field is applied, an abnormally large current flows or particles are aggregated on one electrode.

In the above, particles in which a conductive layer and an insulating layer are sequentially laminated on organic solid particles are used, but a large shear force is not always obtained. Also, as above,
Occasionally, an abnormal current flows or aggregation on the electrodes occurs.

In the above, similarly to the above, particles are settled if left for a long time.

[Problems to be solved by the invention]

The present invention solves the above-mentioned problems, and in addition, provides a sufficiently large shearing force even in a low electric field, does not cause sedimentation of particles even when left for a long time, and is further satisfactory in terms of safety and health. To provide a field-responsive fluid.

[Means for Solving the Problems] The electric field responsive fluid of the present invention is characterized in that particles comprising a derivative of a crosslinked polystyrene having a quaternary ammonium group of 2.0 meq or less per gram are phosphate esters, glycolate esters, citrates. It is characterized by being suspended or dispersed in a liquid medium mainly containing a compound selected from acid esters, glycol derivatives and diethylene glycol esters.

By the way, the present inventors have conducted various studies on the field-responsive fluid, and as a result, as particles dispersed or suspended in liquid-fold (preferably, in a specific solvent), less than 2.0 meq. It has been confirmed that the above-mentioned problem can be achieved when a derivative of a crosslinked polystyrene having a quaternary ammonium group is used. The present invention has been made by this.

 Hereinafter, the present invention will be described in more detail.

The particles in the field-responsive fluid of the present invention are, as described above, a derivative of a crosslinked polystyrene having a quaternary ammonium group of 2.0 meq or less, preferably 1.3 meq or less per gram, and a particle size of 0.1 to 100 μm, preferably 1 to
It has a size of 30 μm.

These particles are obtained by using styrene as a starting material, heating and stirring in the presence of a cross-linking agent such as divinylbenzene to form a cross-linked styrene polymer, which is reacted with an aldehyde and a hydrogen halide, and then alkylated. By reacting with an amine, a crosslinked polystyrene derivative having a quaternary ammonium group can be obtained.

When a polymer having an acid type group is used as particles instead of the particles according to the present invention, there is a disadvantage that sedimentation of the particles easily occurs, but also a disadvantage that a high electric field is required to obtain the same shearing force. is there. Even when a polymer containing a basic type, for example, a primary amine, a secondary amine and / or a tertiary amine group is used as particles, sedimentation easily occurs. When using a derivative of a crosslinked polystyrene polymer having a quaternary ammonium group as particles, if the equivalent of the quaternary ammonium group in the polymer exceeds 2.0 milliequivalents per gram, the specific gravity of the particles increases and sedimentation occurs. It becomes difficult to prevent. Further, when the equivalent weight per gram exceeds 2.0 mm, the value of the current flowing when an electric field is applied to the fluid increases, and the limit value of the electric field that can be applied to the fluid decreases, and the obtained shearing force decreases.

On the other hand, the liquid medium (electrically insulating liquid) for dispersing or suspending such specific particles includes phosphate esters,
One or more mixtures selected from glycolic acid esters, citric acid esters, glycol derivatives, diethylene glycol esters and phthalic acid esters are used. Among these, phosphoric acid esters, glycolic acid esters, citric acid esters, glycol derivatives, and diethylene glycol esters are particularly preferred.

Here, specific examples of the phosphate ester include tricresyl phosphate, triphenyl phosphate, and phenyl-o-phosphate.
-Xenyl, cresyl diphenyl phosphate, trixylenyl phosphate and the like. Specific examples of glycolic acid esters include ethylene phthalyl ethylene glycolate, methyl phthalyl ethylene glycolate, butyl phthalyl butyl glycolate and the like. Specific examples of the citrate include triethyl citrate, acetyl triethyl citrate and the like. Specific examples of the gelcol derivative include glycerin triacetate and glycerin tributyrate. Specific examples of diethylene glycol esters include diethylene glycol benzoate.

In the liquid medium of the present invention, these compounds are contained in the entire liquid medium.
If occupied in an amount of 70% by weight or more, other electrically insulating liquids (aliphatic hydrocarbons, aromatic hydrocarbons, higher fatty acids, silicone oils, etc.) can be added.

Further, in the electric field responsive fluid of the present invention, specific particles are stably suspended or dispersed in a liquid medium (electrically insulating liquid). In addition, it is desirable to add a surfactant.

Such surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkyl sorbitan esters, polyoxyethylene alkyl amines, glycerin fatty esters, Nonionic surfactants such as sorbitan fatty acid esters, propylene glycol fatty acid esters, and polyoxyethylene glycol fatty acid esters; alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl ether acetates, alkylbenzene sulfonates , N-acylamino acid salts, anionic surfactants such as alkylsulfosuccinates and alkylphosphates; quaternary such as benzalkonium salts Cationic surfactants such as amine compounds, perfluoroalkyl phosphoric acid esters, perfluoroalkyl carboxylic acid salts, and fluorine-based surfactants such as perfluoroalkyl betaines and the like.

These surfactants may be used alone or in combination of two or more, if necessary, in the field-responsive fluid. The amount of these surfactants is about 10% by weight or less of the whole fluid.

As described above, the electric field responsive liquid of the present invention can be used or applied in various fields, but when used as an ink for a printer or the like, a dye or pigment is added to color a liquid medium or particles.

When using cationic particles as in the present invention among these coloring agents, dyeing the particles with an anionic dye classified as an acid dye or a direct dye in the color index provides an image without bleeding. It is preferable in forming.
A method of forming an image using such a colored electro-responsive fluid is disclosed in US Pat. No. 4,014,693. Examples of the preferred dyes include the following.

CI Acid Yellow 17,23,38,42,44,79,142 CI Direct Yellow 1,12,24,26,33,44,50,86,14
2,144 CI Food Yellow 3,4 CI Acid Red 1,8,13,14,18,26,27,35,37,42,5
2,82,85,87,89,92,97,106,111,114,115,134,186,249,25
4,289 CI Direct Red 1,4,9,13,17,20,28,31,39,80,8
1,83,89,225,227 CI Food Red 7,9,14 CI Direct Orange 26,29,62,102 CI Acid Blue 9,29,45,80,92,249 CI Direct Blue 1,2,6,15,22,25,71, 76,78,86,8
7,90,98,163,165,202 CI Food Blue 1,2 CI Acid Black 1,2,7,24,26,94 CI Direct Black 19,22,32,38,51,56,71,74,7
5,77,154 CI Food Black 2 Many of these dyes have -SO ₃ Na, 2 or more to one in the dye molecule anionic group such as COONa. For this reason, the quaternary ammonium group to which the dye having a polyvalent anion group binds while the dye of the present invention is well dyed has a low shear force because the anion group hardly moves when an electric field is applied. easy. Therefore, when such a dye is used, it is preferable to set the equivalent of the quaternary ammonium group in the particles to a large value within the range of the present invention.

In addition, in the field-responsive fluid, it is general that the particles have an appropriate amount of water, but have a strongly dissociating group such as a quaternary ammonium group as in the particles according to the present invention. When the particles are used, the type and amount of the counter ion may be selected during the production of the particles without intentionally including moisture in the particles.

〔Example〕

Next, examples and comparative examples will be described. Parts here are by weight.

Example 1 96.5 parts of styrene 3.5 parts of divinylbenzene 1.5 parts of alkylbenzenesulfonic acid 0.2 part of potassium persulfate was added to 300 parts of pure water, stirred, and then heated to obtain a crosslinked styrene polymer. The crosslinked polymer was reacted with paraformaldehyde and hydrogen chloride to form chloromethylated polystyrene, and then reacted with trimethylamine to obtain a polycationic polymer having a quaternary ammonium group. After washing the polymer with dilute hydrochloric acid, washing with pure water,
Further, the suspension was dried by a spray-dry method and vacuum-dried at 60 ° C. to obtain a non-hydrated polymer having a quaternary ammonium group having a counter ion as a chloride ion. The average particle size of the particles was about 0.6 μm, and the number of quaternary ammonium groups was 0.75 meq / g.

The obtained particles were blended according to the following formulation, stirred, and ultrasonically dispersed to obtain an electrically responsive fluid.

Particles 25 parts Trixylenyl phosphate 73.7 parts Kerosene 1.3 parts Put this fluid into a coaxial double cylinder type viscometer, apply a DC voltage between the inner and outer cylinders, apply a rotational force to the outer electrodes, and apply the rotational force to the inner and outer electrodes. The torque at the time of occurrence of a slip was measured, and the shearing force was calculated from this torque and the effective electrode area. The result was 35 gf / cm ² at an electric field of 5 KV / mm.

In order to measure the sedimentation of the fluid, the fluid was placed in a glass test tube with a stopper and allowed to stand at room temperature for 3 months, but no sedimentation of particles was observed.

Comparative Example 1 The dried particles obtained in Example 1 were stirred and dispersed in the following formulation in the same manner as in Example 1 to obtain a fluid, which was tested.

Particles 25 parts Trioctyl trimellitate 75 parts The obtained shearing force was 37 gf / cm ² , which was almost the same as that of Example 1. However, the particles were completely settled after standing for 2 days.

Comparative Example 2 A polymer having a quaternary ammonium group of 2.2 meq / g was obtained in the same manner as in Example 1, except that the reaction time for chloromethylation was lengthened. Using these particles, a fluid having the same formulation as in Example 1 was obtained by the same operation, and a test was conducted. The obtained fluid caused discharge by application of an electric field of about 1.5 KV / mm, and the shear force obtained in an electric field slightly lower than the electric field to be discharged was as low as 12 gf / cm ² .
In addition, in the sedimentation test, sedimentation completely occurred after one week of arrangement.

Comparative Example 3 Particles and a fluid were prepared and prepared in the same manner as in Example 2 except that the liquid medium was trioctyl trimellitate, and this was tested. The obtained shearing force was 35 gf / cm ² at 6 KV / mm, which was almost the same as that of Example 2. However, the particles completely settled after one week of standing.

Comparative Example 4 Particles and a fluid were prepared and prepared in the same manner as in Example 2 except that dioctyl phthalate was used instead of dimethyloctylamine, and this was tested. The obtained shearing force was 30 gf / cm ² at 6 KV / mm, which was almost the same as that of Example 2. However, as in Comparative Example 3, the particles completely settled after being left for one week.

Comparative Example 5 A crosslinked polymer having a quaternary ammonium group of 2.2 meq / g was obtained in the same manner as in Comparative Example 2 except that dimethyloctylamine was used instead of trimethylamine. A fluid was prepared and tested in the same manner as in Example 2 except that the particles were used in place of the particles of Example 2. The resulting fluid produced a discharge at an electrolysis of about 2.0 KV / mm. The shear force obtained in an electric field slightly lower than the electric field to be discharged was as low as 14 gf / cm ² . In addition, the particles completely settled after being left for one week.

Example 2 A crosslinked polymer having a quaternary ammonium group of 0.3 meq / g was obtained in the same manner as in Example 1 except that the reaction time of chloromethylation was shortened and triethylamine was used instead of trimethylamine. Was. Using the particles, a fluid having the following formulation was prepared and tested in the same manner as in Example 1.

Particles 25 parts Diethylene glycol dibenzoate 68 parts Silicone oil 7 parts The obtained shearing force was 35 gf / cm ² in an electric field of 7 KV / mm, and there was no sedimentation of the particles even after standing for 3 months.

Example 3 Example 1 except that the reaction time for chloromethylation was increased.
By performing the same operation as described above, particles having a quaternary ammonium group of 1.6 meq / g were obtained. 10 g of the particles obtained above was placed in an aqueous solution in which 1 g of Direct Blue 86 was dissolved in 10 ml of water to adsorb the dye. The dyed particles were washed with water and dried to obtain colored particles. Subsequently, a fluid having the following formulation was prepared and tested in the same manner as in Example 1.

Colored particles 25 parts Methylphthalylethyl glycolate 74 parts Triethyl citrate 1 part The obtained shear force was 28 gf / cm ² at 4 KV / mm.
In addition, no sedimentation of particles was observed when the fluid was left for 3 months.

〔The invention's effect〕

According to the electric field responsive fluid of the present invention, the following effects can be obtained.

(1) Since a polymer crosslinked product containing quaternary ammonium ions is used as particles, a large shearing force can be obtained even at a relatively low electric field, and at the same time, the ion density can be maintained at 2.0 meq / g or less. Prevention of discharge by application and reduction of specific gravity of particles can be achieved.

(2) The combination of a liquid medium having relatively high integrity, high electrical resistance, high specific gravity, and low specific gravity, prevents particles from settling due to long-term storage of the fluid, and ensures reliability. And safety can be improved.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI C10N 40:14 (58) Investigated field (Int.Cl. ⁶ , DB name) C10M 105 / 74,105 / 36 C10M 105 / 38,107 / 42 C10N 40: 14

Claims (2)

(57) [Claims] 1. A particle comprising a derivative of a crosslinked polystyrene having a quaternary ammonium group of not more than 2.0 meq / g is a compound selected from phosphate esters, glycolates, citrates, glycol derivatives and diethylene glycol esters. An electro-responsive fluid which is suspended or dispersed in a liquid medium mainly used. 2. The phosphoric acid ester is tricresyl phosphate, triphenyl phosphate, phenyl-o-xenyl phosphate, cresyl diphenyl phosphate, trixylenyl phosphate, and glycolic acid ester is ethylphthalylethyl glucorate, methyl Phthalyl ethyl glucorate, butyl phthalyl butyl glycolate, citrate ester is triethyl citrate, acetyl citrate triethyl, glycol derivative is glycerin triacetate, glycerin tributyrate, diethylene glycol ester is a compound each selected from diethylene glycol benzoate An electroactive fluid according to claim 1.