JP2006002027A - Dilatant fluid composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel dilatant fluid which can be a liquid over a wide range of temperature, is excellent in shelf life, has a great mechanical strength, and exhibits a very large change in viscous resistance with increased shear stress. <P>SOLUTION: The dilatant fluid composition comprises (A) 100 pts.mass. of a silicone resin powder, (B) 1.0-100 pts.mass. of a particle dispersant, and (C) 10-500 pts.mass. of a silicone medium, wherein the silicone resin powder comprises one or more constituent units selected from [R<SP>1</SP>SiO<SB>3/2</SB>], [R<SP>1</SP><SB>2</SB>SiO<SB>2/2</SB>], [R<SP>1</SP><SB>3</SB>SiO<SB>1/2</SB>], and [SiO<SB>4/2</SB>], has the [R<SP>1</SP>SiO<SB>3/2</SB>] unit as the main component, and has an organic solvent-insoluble primary particle size of 100 nm-1 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluid exhibiting dilatancy that becomes highly viscous under a high shearing force and low viscosity under a low shearing force. Such a fluid is arranged between two closely moving objects, and transmits a high torque under a high shear speed and a clutch or vibration isolator that transmits a low torque under a low shear speed. It is useful as a working fluid.

  Conventionally, in a liquid in which fine particles are dispersed, when a shearing force is applied, a low viscosity is exhibited under a low shearing force, but when the applied shearing force is increased, a phenomenon in which the viscosity is rapidly increased, that is, dilatancy is exhibited. It is known.

  This dilatancy is a phenomenon that occurs because the packed state of particles temporarily changes due to a sudden external force. For the sake of simplicity, when considering a collection of spherical particles of the same size, the porosity is 26% in the closest packing. In this state, the spherical particle aggregate can flow gently if it absorbs enough liquid to fill the space between the particles. However, now, when a strong external force is applied suddenly, the aggregate of spherical particles shifts to a sparse packking state.

  For example, in the least-packed packing, since the porosity is 48%, it is not enough even if the liquid is completely sucked into the increased space, and particles that rub against each other without being immersed in the liquid are formed.

  This is why in the dilatancy, the surface liquid is sucked into the interior, the volume expands, the fluidity is lost, and it behaves like a brittle solid. For example, if you step on the wet sandy beach, the gap between the sand grains will widen, the seawater will be sucked into the sand, and the sandy land will appear dry and hard. A dilatancy phenomenon is also observed when the crystal precipitate is suction filtered.

  Dilatal (registered trademark) manufactured by BASF Germany is known as a fluid exhibiting dilatancy. This is a dispersion of acrylate-styrene copolymer fine particles in water. JP-A-8-281095 reports a liquid exhibiting dilatancy composed of inorganic compound fine particles having a sphericity of 1.1 or less and a liquid. In this claim, silicone oil is used. Are listed.

  Conventionally, a known dilatancy fluid has a problem that the dispersion medium is water or a volatile solvent, so that the dispersion medium is solidified at a low temperature and easily volatilized at a high temperature. Moreover, even when it does not reach that point, there is a problem that the viscosity change is severe and it can be used only near room temperature.

  Japanese Patent Application Laid-Open No. 8-281095 describes the use of “silicone oil” as a medium, but there is no detailed description of silicone oil, and there is no description of a particle dispersant when silicone oil is used. Therefore, the dispersed particles are difficult to be compatible with the medium silicone oil, the particles cannot be uniformly dispersed and highly blended, and they are liable to settle and have poor storage stability.

  In addition, in the case of inorganic particles, particularly silica, pseudo-aggregation with time may occur due to the surface activity, and fluidity may be lost.

  Japanese Patent Application Laid-Open No. 10-251517 uses a silicone resin powder having an average particle size of 10 to 40 μm. However, a powder having a large particle size is liable to settle and has a disadvantage of poor storage stability.

Japanese Patent Laid-Open No. 8-28955 JP-A-10-251517

  An object of the present invention is to provide a novel dilatancy fluid that retains a liquid state over a wide temperature range, has excellent storage stability, has high mechanical strength, and has a very large amount of change in viscous resistance due to an increase in shear stress. There is to do.

As a result of intensive studies to solve the above problems, the inventors have found that [R ¹ SiO _3/2 ], [R ¹ ₂ SiO _2/2 ], [R ¹ ₃ SiO _1/2 ], [SiO _4/2 ]. 100 parts by mass of a silicone resin powder having a primary particle size of 100 nm to 1 μm insoluble in an organic solvent, the main component of which is a [R ¹ SiO _3/2 ] unit. On the other hand, in a composition comprising 1.0 to 100 parts by mass of a particle dispersant and 10 to 500 parts by mass of a silicone medium, a dilatancy fluid that becomes a sol under a low shear force and becomes a gel under a high shear force. I found it.

  This dilatancy fluid is excellent in storage stability, maintains a liquid state over a wide temperature range, has high mechanical strength, and has a large amount of change in viscous resistance accompanying an increase in shear stress.

  The dilatancy fluid of the present invention retains a liquid state in a wide temperature range, has excellent storage stability, has high mechanical strength, and has a large amount of change in viscous resistance accompanying an increase in shear stress. Therefore, the dilatancy fluid of the present invention is useful as a working liquid for clutches and vibration isolators.

The present invention will be described in detail below. The present invention relates to one or more structures selected from [R ¹ SiO _3/2 ], [R ¹ ₂ SiO _2/2 ], [R ¹ ₃ SiO _1/2 ], [SiO _4/2 ]. 100 to 100 parts by mass of a particle dispersant with respect to 100 parts by mass of a silicone resin powder having a primary particle size of 100 nm to 1 μm insoluble in an organic solvent, the main component being [R ¹ SiO _3/2 ] units. This is based on the finding that the composition comprising 10 parts by mass and 10 to 500 parts by mass of the silicone medium expresses an extremely specific dilatancy.

The silicone resin powder constituting the present invention is 100 nm to 1 μm, more preferably 300 to 900 nm.
If the particle size is too large, it is difficult to show dilatancy, and the dispersion of the particles becomes unstable and settles to separate from the dispersion medium. If the particle size is too small, the viscosity in the sol state increases, the fluidity is lost, and it is difficult to show dilatancy, which is not preferable.

  The surface state of the silicone resin powder in the present invention is smoother with less irregularities, and is more preferably closer to a sphere.

The monodispersed spherical silicone resin powder having a particle size of 1 μm or less in the present invention can be produced by a known method described in JP-A-6-192426. That is, A) tetraalkoxysilane which is a raw material of [SiO _4/2 ], a trialkylsilanol which is a raw material of [R ¹ ₃ SiO _1/2 ] and an organotrile which is a raw material of [R ¹ SiO _3/2 ]. A step of hydrolyzing and condensing an alkoxysilane and, if necessary, a silane mixture comprising diorganodialkoxysilane, which is a raw material of [R ¹ ₂ SiO _2/2 ], in an aqueous solution of an alkaline substance; B) By a production method comprising the steps of adding organotrialkoxysilane and subsequently hydrolyzing and condensing, the primary particle diameter is 1 μm or less, and the deviation of the particle diameter value from the average particle diameter value is Monodispersed spherical silicone resin fine particles in the range of 0.1 μm or less can be efficiently produced with easy process control.

  Monodispersed spherical silicone resin powders having a particle size of 1 μm or less are commercially available as X-52-854 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) and Tospearl 105 (trade name, manufactured by GE Toshiba Silicone). Can be used.

  The surface of the silicone resin powder of the present application may not be particularly treated, but for the purpose of preventing aggregation and moisture absorption in the powder state, a perfluoroalkyl group-containing silazane and an unsubstituted hydrocarbon group having 1 to 5 carbon atoms. The surface may be silylated with silazane consisting of Further, other physical properties of the particles, the amount of impurity components, etc. are not particularly limited.

  The particle dispersant in the present invention is used in order to improve the affinity of the silicone resin powder to the silicone medium and to make it highly blended, and it is preferable to use a dispersant having the following siloxane bond.

A siloxane represented by the following general formula (1).
R ¹ _a R ² _b SiO _{(4-ab) / 2} (1)
[However, R ¹ in the formula is an alkyl group, a cycloalkyl group, an aryl group, or the like or different organic groups selected from monovalent hydrocarbon group having 1 to 30 carbon atoms or an aralkyl group, R ² is A substituent having an alkylene oxide group and a hydroxyl group. A and b are 0.01 ≦ a ≦ 2.5 and 0.01 ≦ b ≦ 2.5, respectively, and 0.05 <a + b ≦ 3.0, and c and d are 2 ≦ c, respectively. ≦ 5, 0 ≦ d ≦ 100. ]

Specific examples of R ^{1 in} the general formula (1) include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group and other alkyl groups, cyclopentyl Groups, cycloalkyl groups such as cyclohexyl group, aryl groups such as phenyl group and tolyl group, aralkyl groups such as benzyl group and phenethyl group.

  Moreover, although the average molecular weight of the silicone compound represented by Formula (1) is not specifically limited, It is preferable that it is 500-10,000, and it is especially preferable that it is 1,000-5,000.

  Specific examples of the particle dispersant as the component (B) in the present invention include polysiloxane diols represented by the following general formulas (2) and (3).

但し、Ｒ^３は各々独立して、炭素数１〜８アルキル基またはアリール基を示す。具体的には、アルキル基としては、メチル基、エチル基、オクチル基が好ましく、アリール基としてはフェニル基が好ましい。また、Ｒ^４は各々独立してアルキレン基或いはエステル結合又はエーテル結合を有する二価の置換基を示す。具体的には、エチレン基、トリメチレン基、２−オキサペンタメチレン基、３−オキサヘキサメチレン基等が好ましい。ｄは１≦ｄ≦１０００の整数である。

However, R < ³ > shows a C1-C8 alkyl group or an aryl group each independently. Specifically, the alkyl group is preferably a methyl group, an ethyl group or an octyl group, and the aryl group is preferably a phenyl group. R ⁴ each independently represents an alkylene group or a divalent substituent having an ester bond or an ether bond. Specifically, an ethylene group, a trimethylene group, a 2-oxapentamethylene group, a 3-oxahexamethylene group, and the like are preferable. d is an integer satisfying 1 ≦ d ≦ 1000.

  More preferred is a one-end hydroxyl group-containing silicone oil represented by the following formula.

（但し、式中のＲ^３は上記した基を示し、ｄは１≦ｄ≦１０００、ｃは２≦ｃ≦５の整数である。）

(However, R ³ in the formula represents the above-mentioned group, d is an integer of 1 ≦ d ≦ 1000, and c is an integer of 2 ≦ c ≦ 5.)

As another specific example of the particle dispersant as the component (B) in the present invention,
It is a copolymer of a (meth) acryl monomer and one-terminal (meth) acryl group-containing siloxane. The amount of siloxane modification of the copolymer is preferably 30 to 95% by weight, more preferably 60 to 90%.

Such a copolymer is obtained by copolymerizing a (meth) acrylic group-containing siloxane represented by the following general formula (4) and a (meth) acrylic monomer represented by the following general formula (7). Examples include acrylic-silicone copolymers.
Specifically, 30 to 95% by weight of a (meth) acryl group-containing siloxane compound represented by the following general formula (4),

［式中、Ａは下記一般式（５）又は（６）
ＣＨ_２＝Ｃ（Ｒ^６）ＣＯＯＲ^７− （５）
ＣＨ_２＝Ｃ（Ｒ^６）Ｃ_６Ｈ_５− （６）
（式中、Ｒ^６は水素又はメチル基、Ｒ^７は炭素数１〜１０のアルキレン基、ｎは３〜５００の整数を表す。）で表されるラジカル重合性基、Ｒ^５は、それぞれ同種あるいは異種でもよい、炭素数１〜３０のアルキル基、アリール基、アラルキル基及びフッ素置換アルキル基から選択される有機基を表す。］
及び、下記一般式（７）で表される（メタ）アクリルモノマー７０〜５重量％、
ＣＨ_２＝Ｃ（Ｒ^８）ＣＯＯＲ^９ （７）
（式中、Ｒ^８は水素又はメチル基、Ｒ^９は炭素数１〜３０のアルキル基を表す。）を共重合させて得られることを特徴とするアクリル−シリコーン系共重合体が挙げられる。

[Wherein A represents the following general formula (5) or (6)
^{_{CH 2 = C (R 6)}} COOR 7 - (5)
_{^{CH 2 = C (R 6)}} C 6 H 5 - (6)
(Wherein R ⁶ is hydrogen or a methyl group, R ⁷ is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 3 to 500), and R ⁵ is the same type. Alternatively, it represents an organic group selected from an alkyl group having 1 to 30 carbon atoms, an aryl group, an aralkyl group, and a fluorine-substituted alkyl group, which may be different. ]
And 70 to 5% by weight of a (meth) acrylic monomer represented by the following general formula (7):
CH ₂ = C (R ⁸ ) COOR ⁹ (7)
And an acrylic-silicone copolymer obtained by copolymerizing (wherein R ⁸ represents hydrogen or a methyl group, and R ⁹ represents an alkyl group having 1 to 30 carbon atoms).

The organopolysiloxane compound having a radical polymerizable group represented by the general formula (4) is called a silicone macromonomer, and is a compound having a radical polymerizable group only at one end. Here, A represents a monovalent organic group having radical polymerizability, and can be represented by the above general formula (5) or (6). Specifically, (meth) acrylic acid methyl group, (meth) acrylic acid Examples include a propyl group, a (meth) acrylic acid decyl group, a styryl group, an α-methylstyryl group, and the like. Specific examples of R ¹ include methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, cyclohexyl groups and other alkyl groups, phenyl groups, and tolyl groups. Aryl groups such as benzyl group and phenethyl group, and fluorine-substituted alkyl groups such as trifluoropropyl group and nonafluorobutylethyl group.

  Specific examples of the acrylic monomer of the general formula (7) include methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. T-butyl acid, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, etc. These may be used alone or in combination of two or more.

  The proportion used for the copolymerization of the compounds represented by the general formulas (4) and (7) is 30 to 95% by weight of the organopolysiloxane compound having a radical polymerizable group of the general formula (4), preferably 60 to 90% by weight, and the acrylic monomer of the general formula (7) is 5 to 70% by weight, preferably 10 to 40% by weight.

The silicone of the dispersion medium is preferably a cyclic or linear dimethyl silicone oil or methylphenyl silicone oil, more preferably an oil having a boiling point higher than 100 ° C. and a viscosity of 100,000 mm ² / s or less. When the boiling point is 100 ° C. or lower, the volatility is high and the weight decreases with time, and the composition and dilatancy change.

Further, when the oil has a viscosity of 100,000 mm ² / s or more, the amount of the silicone resin powder cannot be increased, and as a result, the difference between the viscosity at low torque and the viscosity at high torque becomes small.

The silicone of the dispersion medium as component (C) is preferably a cyclic or linear dimethyl silicone oil or methyl phenyl silicone oil, more preferably an oil having a boiling point higher than 100 ° C. and a viscosity of 100,000 mm ² / s or less. preferable. When the boiling point is 100 ° C. or lower, the volatility is high and the weight decreases with time, and the composition and dilatancy change. In addition, when the oil has a viscosity of 100,000 mm ² / s or more, the amount of inorganic particles cannot be increased, and as a result, the difference in viscosity between low torque and high torque becomes small.

  In the dilatancy fluid of the present invention, the mixing ratio of the particle dispersant with respect to 100 parts by mass of the silicone resin powder is 1.0 to 100 parts by mass. More preferably, it is 2-50 mass parts. If the mixing ratio of the particle dispersant is small, the dispersion of the silicone resin powder is poor and a uniform fluid composition cannot be obtained. On the other hand, if the amount is too large, dilatancy characteristics cannot be obtained.

  A preferable mixing ratio of the silicone medium to 100 parts by mass of the silicone resin powder is 10 to 500 parts by mass, and more preferably 20 to 300 parts by mass. If the amount of silicone oil is small, a uniform fluid composition cannot be obtained. Conversely, if the amount is too large, dilatancy characteristics cannot be obtained.

The composition of the present invention can be prepared by a known method.
(Dispersant treatment method for particles)
The particle dispersant can be treated on the particle surface by a known method. For example, it is possible to appropriately select from the following methods.
(1) A method in which target particles are surface-treated by dispersing them in a medium selected from organic solvents mixed with a treatment agent.
(2) A method of performing surface treatment using a pulverizer such as a ball mill or a jet mill after mixing particles and a particle treatment agent.
A treatment method in which a treatment agent is blended in a solvent, particles are dispersed and adsorbed on the surface, and then dried.

(Method for producing powder dispersion in oil)
The surface-treated particle dispersion can be produced by a known method. For example, (1) A method in which the dispersant-treated silicone resin powder composition obtained as described above is added and dispersed in an oil agent such as silicone oil.
(2) It can be easily obtained by, for example, a method in which a particle dispersant is dissolved or dispersed in a silicone medium, and a silicone resin powder is added thereto and mixed with a dispersing device such as a ball mill, a bead mill, a sand mill, or a planetary mixer.

  In the dilatancy fluid of the present invention, by adding a fluidity improver to control the polarity, it is possible to change the dispersion state of the silicone resin powder and improve the fluidity.

  Furthermore, it is good also as a grease-like thing which is hard to flow under a low shear force or atmospheric pressure by adding a thickener and a gel-like substance and giving thixotropic property.

  As a method for producing the dilatancy liquid of the present invention, the silicone resin powder, the particle dispersant, and the silicone medium are stirred and dispersed uniformly at a high temperature of 60 ° C. or higher, or the silicone resin powder is dispersed in the silicone medium. And a method of gradually adding and dispersing the particle dispersant with stirring.

  The dilatancy fluid composition of the present invention is useful as a damper material or a working liquid for a torque transmission device such as a clutch or a vibration isolating / isolating device.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

[Example 1]
To a mixed solution of 25 parts by mass of dimethylsiloxane [trade name: KF96 (10 cs) manufactured by Shin-Etsu Chemical Co., Ltd.] and 5 parts by mass of one-end carbinol-modified oil represented by the following formula (7), silicone resin powder [ Shin-Etsu Chemical Co., Ltd. product name: X-52-854] (average primary particle size = 800 nm) was mixed with a planetary mixer to obtain a white liquid.

(Example 2)
Silicone resin powder [trade name, manufactured by Shin-Etsu Chemical Co., Ltd.] is added to a mixed solution of 30 parts by mass of decamethylcyclopentasiloxane and 5 parts by mass of a one-end carbinol-modified oil represented by the same formula (7) as in Example 1. : X-52-854] (average primary particle size = 800 nm) 65 parts by mass was mixed with a planetary mixer to obtain a white liquid.

Example 3
Silicone was added to a mixed solution of 30 parts by mass of dimethylsiloxane [trade name: KF96 (20cs) manufactured by Shin-Etsu Chemical Co., Ltd.] and 5 weights of one-end carbinol-modified siloxane represented by the same formula (7) as in Example 1. 65 parts by mass of resin powder [trade name: X-52-854, manufactured by Shin-Etsu Chemical Co., Ltd.] (average primary particle size = 800 nm) was mixed with a planetary mixer to obtain a white liquid.

(Comparative Example 1)
Silicone resin powder [trade name: KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd.] (average primary particle size = 2 μm) 65 parts by mass, decamethylcyclopentasiloxane 30 parts by mass, and the same formula (7) as in Example 1 And 5 parts by mass of one-end carbinol-modified siloxane represented by the formula (1) were mixed with a planetary mixer to obtain a white paste.

(Comparative Example 2)
Silicone resin powder [manufactured by Shin-Etsu Chemical Co., Ltd.] is added to a mixed solution of 15 parts by mass of decamethylcyclopentasiloxane and 20 parts by mass of a one-end carbinol-modified oil represented by the same formula (7) as in Example 1. Name: KMP-590] (average primary particle size = 2 μm) 65 parts by mass was mixed with a planetary mixer to obtain a white paste.

  About each liquid obtained by the above Examples 1-3 and Comparative Examples 1-2, the viscosity (unit Pa * s) in 25 degreeC using the Malcolm viscometer (model PC-1TL) by Malcolm Co., Ltd. The results are shown in FIG.

  Furthermore, about the liquid obtained in Example 1, the viscosity (unit Pa * s) in -5 to 60 degreeC was measured using the Malcolm viscometer (model PC-1TL) by Malcolm Co., Ltd., and the result Is shown in FIG.

  About each liquid obtained in Examples 1-3 and Comparative Examples 1-2, the uniformity was visually observed about the sedimentation degree of the particle | grains after 1 month at 25 degreeC and 10 days after 60 degreeC. The evaluation results are shown in Table 1.

(Summary of Examples)
As can be seen from the above results, in the composition of the present invention, as the rotor rotates at a higher speed, the viscosity increases, that is, dilatancy is recognized. Moreover, when water is used as a solvent, it can be seen that dilatancy is exhibited even at −5 ° C., which is the temperature at which water solidifies. Dilatancy is also observed at a high temperature of 60 ° C. In addition, regarding storage stability, particles are likely to settle in the comparative example, but very difficult to settle in the examples.

It is a viscosity change figure of the dilatancy liquid concerning the present invention. (Examples 1-3 and Comparative Examples 1-2) It is a viscosity change figure of the dilatancy liquid concerning the present invention. (Example 1)

Claims (4)

(A) ^One or more structural units selected from [R ¹ SiO _3/2 ], [R ¹ ₂ SiO _2/2 ], [R ¹ ₃ SiO _1/2 ], [SiO _4/2 ] A silicone resin powder comprising [R ¹ SiO _3/2 ] units as a main component and having a primary particle size of 100 nm to 1 μm insoluble in an organic solvent
100 parts by weight (B) Particle dispersant 1.0 to 100 parts by weight (C) Silicone medium A dilatancy fluid composition comprising 10 to 500 parts by weight. The dilatancy fluid composition according to claim 1, wherein the particle dispersant according to claim 1 is a dispersant having a siloxane bond. The diancy fluid composition according to claim 1, wherein the particle dispersant according to claim 2 is a siloxane according to the following general formula (1).
R ¹ _a R ² _b SiO _{(4-ab) / 2} (1)
[However, R ¹ in the formula is an alkyl group, a cycloalkyl group, an aryl group, or the like or different organic groups selected from monovalent hydrocarbon group having 1 to 30 carbon atoms or an aralkyl group, R ² is A substituent having an alkylene oxide group and a hydroxyl group. A and b are 0.01 ≦ a ≦ 2.5 and 0.01 ≦ b ≦ 2.5, respectively, and 0.05 <a + b ≦ 3.0, and c and d are 2 ≦ c, respectively. ≦ 5, 0 ≦ d ≦ 100. ] The dilatancy fluid composition according to claim 1, wherein the silicone medium according to claim 1 is a cyclic or linear dimethyl silicone oil or methylphenyl silicone oil.

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