JP4444785B2 - Colloidal damper - Google Patents

Description

  The present invention relates to a colloidal damper.

  A colloidal damper is a device that dissipates mechanical energy acting from the outside, and encloses a mixture of a porous body and a liquid in a container, and mechanical energy from the outside acts on this mixture. The structure is pressurized. When the mixture is pressurized, the liquid enters the pores of the porous body, and at that time, the mechanical energy can be attenuated. The present inventors have already made proposals for improving the performance of such colloidal dampers (see Patent Document 1 below).

  By the way, in order to put this type of colloidal damper into practical use, it is necessary to maintain the performance as a colloidal damper even if it is repeatedly used practically many times. And it is already known that it is preferable that the surface of the porous body has lyophobic properties with respect to the liquid as a requirement necessary to enable repeated use (see paragraph of Patent Document 1 below) [0017]).

  For example, when the liquid is water, it is preferable to combine a porous body having a hydrophobic surface with low affinity with water, and conversely, when the porous body has a hydrophilic surface, It is preferable to combine mercury or the like having a low affinity with the surface.

  When the porous body and the liquid are selected in such a combination, the liquid that has entered the pores in the pressurization step is reversibly discharged out of the pores in the decompression step. In the pressurizing step, a sufficient amount of liquid can be infiltrated into the pores, so that the performance of the colloidal damper is unlikely to deteriorate even when used repeatedly.

Furthermore, even when the porous body itself has a hydrophilic surface, the surface of the porous body can be treated with a hydrophobic substance to modify the liquid so that it is hydrophobic. It is already known that it will be possible. As an example of such a hydrophobic substance, in Patent Document 1 below, trimethylchlorosilane and dimethyloctadecylchlorosilane are exemplified, and it is described that a substance having a long molecular chain length is preferable (paragraph of Patent Document 1 below) [0018]).
JP 2004-44732 A

  However, as described above, it has been known that a hydrophobic substance having a long molecular chain length tends to be preferable, but to what extent a long molecular chain length is effective, the molecular chain length is There were still unclear points, such as whether the longer the better.

  Under these backgrounds, the present inventors have further investigated a hydrophobic substance used to make the porous body hydrophobic. As a result, in order to improve the performance of the colloidal damper, the longer the molecular chain length is not necessarily better, it is effective to keep the molecular chain length of the hydrophobic substance within a certain numerical range, In addition, new findings have been obtained, such as setting the molecular chain length in consideration of the relationship with the pore diameter.

  The present invention has been completed on the basis of the above-described new knowledge, and its object is to make use of a hydrophobic porous material obtained by surface-treating a hydrophilic porous material with a hydrophobic substance. An object of the present invention is to provide a colloidal damper having an optimized thickness of a hydrophobic film formed on the surface of a hydrophobized porous body.

The characteristic configuration employed in the present invention will be described below.
The colloidal damper of the present invention is
By treating the surface of the hydrophilic porous body with a hydrophobic substance, the hydrophobic porous body modified to exhibit hydrophobicity, the hydrophilic liquid, the liquid, and the hydrophobic porous body A container for containing the mixture, and a transmission means for increasing or decreasing the pressure acting on the mixture by transmitting the pressure from the outside to the mixture in the container, the pressure from the outside acting on the transmission means Accordingly, when the pressure acting on the mixture increases, the liquid penetrates into the pores of the hydrophobic porous body, and the external pressure acting on the transmission means is attenuated as the liquid enters. A colloidal damper,
The hydrophobic substance is a compound capable of replacing hydrogen in a hydroxyl group present on the pore surface of the hydrophilic porous body with an organic hydrophobic group,
The organic hydrophobic group is represented by the following general formula (1), and the head (HEAD) has a radius R _W based on the van der Waals radius of the atomic group constituting the head (HEAD) and the body (BODY). hemispherical, it has become barrel portion (bODY) in a cylindrical shape and can assume molecular structure of radius _{R W, - (bODY) m} - molecular chain length h of (HEAD) is, the barrel of (bODY) In relation to the contact angle θ _B , it is a value satisfying h> [− R _W / (2 cos θ _B ) +0.24] (nm).

In the present invention, typical examples of the hydrophilic liquid include water, but in addition to this, it is possible to use all liquids having affinity similar to water for the hydrophobic porous body. it can. As a liquid other than water, for example, a mixture of water and an antifreeze (for example, glycerin, ethylene glycol, propylene glycol, etc.) can be used. In this case, a colloidal damper should be used even in an environment of 0 ° C. or lower. Will be able to. In addition, a mixture of water and a substance that is harder to evaporate than water (for example, dimethylformamide, formamide, etc.) can be used. In this case, the colloidal damper can be used even in an environment of 100 ° C. or higher. Become.

In the present invention, first, the minimum thickness of the hydrophobic film to be formed on the pore surface of the hydrophilic porous body was examined.
In the colloidal damper of the present invention, the body (BODY) and the head (HEAD) of the organic hydrophobic group have a structure in which specific atomic groups as described above are combined. Therefore, the-(BODY) _m- (HEAD) part in the organic hydrophobic group is based on the van der Waals radii of the atomic groups constituting the head (HEAD) and the body (BODY). the radius R _W of hemispherical, can be assumed barrel to (bODY) to the radius R _W of the cylindrical shape.

  Further, the organic hydrophobic group represented by the general formula (1) forms a hydrophobic film on the pore surface of the hydrophilic porous body, but the density of hydroxyl groups present on the pore surface of the hydrophilic porous body is low. When the surface is sufficiently high (for example, 2.3 to 4.8 hydroxyl groups per square nanometer are present), the organic hydrophobic groups are critical density (close-packed state) on the pore surface of the hydrophilic porous body. A brush-like structure is formed in which the organic hydrophobic groups are arranged in such a manner that the bristles of the brush are arranged in such a density that can be regarded as the same.

  Furthermore, all the hydroxyl groups present on the pore surfaces of the hydrophilic porous body are not replaced by organic hydrophobic groups, and hydroxyl groups remain between the organic hydrophobic groups. Since this residual hydroxyl group is structurally sufficiently smaller than the organic hydrophobic group, it exists in the vicinity of the base portion between the organic hydrophobic groups arranged in a critical density, and remains without being replaced by the organic hydrophobic group.

  When a colloidal damper is formed using a hydrophobic porous body having a hydrophobic membrane with a brush-like structure on its surface and this hydrophilic liquid, the liquid penetrates into the pores when pressurized. Furthermore, the liquid that has entered the pores also enters microscopically between the organic hydrophobic groups that form the brush-like structure.

  On the other hand, since the liquid has a low affinity for the organic hydrophobic group and the contact angle to the surface of the organic hydrophobic group is greater than 90 degrees, the surface tension of the liquid acts to discharge the liquid from between the organic hydrophobic groups, Further, the liquid is discharged from the pores whose surfaces are covered with the organic hydrophobic group.

Therefore, if the liquid is in an ideal state in contact with only the organic hydrophobic group, the liquid is expected to be reversibly discharged out of the pores as the pressure is reduced.
However, there is a residual hydroxyl group between the organic hydrophobic groups in the pores as described above. When this residual hydroxyl group and a liquid form a hydrogen bond, the liquid is not discharged from between the organic hydrophobic groups even under a reduced pressure condition. Is not reversibly discharged out of the pores, which is a factor that degrades the performance of the colloidal damper.

Therefore, in the present invention, first, the molecular chain length of-(BODY) _m- (HEAD) should be made longer than the extent that the liquid infiltrated between the organic hydrophobic groups and the residual hydroxyl group do not form hydrogen bonds. Thought. When considering the distance from the surface of the pore, the tip of the remaining hydroxyl group is almost at the same position as Si in the organic hydrophobic group, and the thickness of the hydrophobic film that inhibits the formation of hydrogen bonds with the remaining hydroxyl group is , − (BODY) _m − (HEAD) molecular chain length, and if the minimum value of this molecular chain length can be found, the molecular length of the organic hydrophobic group is excessively increased. It is thought that it may not be necessary.

FIG. 1 is a graph in which a model of an organic hydrophobic group is shown on the left side and a graph of the energy state E _C of a liquid that has entered between the organic hydrophobic groups is shown on the right side. Model of organic hydrophobic groups drawn on the left side, the head (HEAD) and the body portion based on the van der Waals radii of atomic group forming a (BODY), the head (HEAD) the radius R _W of hemispherical, barrel (bODY) a has become cylindrical and the assumed model of radius R _W, the vertical axis represents the distance from the head side of the organic hydrophobic groups. In the graph drawn on the right side, the horizontal axis indicates the height of the energy E _C , and there are stable points with low energy states at two points, point B and point D, between point B and point D. This indicates that there is a point C as an energy barrier.

When the external pressure p is smaller than the average compression (adsorption) pressure (for example, in FIG. 6A, in the case of C1, the average compression (adsorption) pressure is about 20 MPa), the liquid does not enter the pores. When the external pressure p becomes equal to the average compression (adsorption) pressure, the liquid enters the pores. At this time, since the energy state at the point B is smaller than the energy state at the point A, when the liquid enters the pores, the organic hydrophobic group reaches the position of the point B while contacting the head of the organic hydrophobic group. It will intrude in between. When the external pressure p becomes larger than the average compression (adsorption) pressure (for example, in FIG. 6, the maximum external pressure is 60 MPa), the liquid is forcibly pushed between the organic hydrophobic groups. When the energy required to exceed the C point is given from the outside, the liquid further penetrates into the back between the organic hydrophobic groups. The problem is how far the liquid penetrates between the organic hydrophobic groups. Since the G point has the same energy state as the C point, the liquid first penetrates between the organic hydrophobic groups up to the G point. Furthermore, when energy is input to the system from the outside, the energy state becomes larger than the point G, and it is generally considered that the liquid can penetrate to the point I. However, the relationship between the energy state E _{C of the} liquid and the equivalent contact angle θ is E _C = −cos θ, and the equivalent contact angle θ is obtained from a mathematical condition that the cosine function (cos) is smaller than 1 (± cos θ ≦ 1). And the y-axis relationship of FIG. 1, an inequality of y ≦ −R _W / (2 cos θ _B ) can be obtained. Therefore, the liquid cannot penetrate below the H point (y> −R _W / (2 cos θ _B )). This can be said to be correct because the energy states at point H and point A are equal in FIG.

  On the other hand, when the pressure from the outside does not act, the liquid having low affinity for the organic hydrophobic group is discharged from between the organic hydrophobic groups due to the surface tension of the liquid. However, in order to reversibly enter and discharge the liquid, it is necessary to prevent the liquid that has entered between the organic hydrophobic groups up to the H point from forming a hydrogen bond with the remaining hydroxyl group present on the base side (BASE). .

Here, the liquid that has penetrated to the point H may form hydrogen bonds when approaching 0.24 (nm) with respect to the hydroxyl group (Reference: Pauling, L., The Chemical Bond. A Brief Introduction to Modern Structural Chemistry, Cornell University Press, New York, 1967). For these reasons, in order to prevent the liquid that has penetrated to the point H from forming a hydrogen bond with the remaining hydroxyl group present on the base side, the molecular chain length h of-(BODY) _m- (HEAD) is set to h It can be said that> [− R _W / (2 cos θ _B ) +0.24] (nm) is preferable.

As described above, the molecular chain length h of − (BODY) _m − (HEAD) is related to the contact angle θ _B of the body (BODY), h> [− R _W / (2 cos θ _B ) +0. 24] (nm), the thickness of the hydrophobic film becomes thicker than the minimum film thickness necessary for preventing hydrogen bond formation between the liquid and the remaining hydroxyl group. Therefore, unlike colloidal dampers, where the liquid that has entered the pores tends to form hydrogen bonds with the remaining hydroxyl groups and the liquid remaining in the pores gradually increases, the colloidal damper is used over and over again. become able to.

As a more specific example, for example, the liquid is water, the hydrophilic porous body is silica gel, the organic hydrophobic group is CH _{3 in} the head (HEAD), and the body (BODY) is CH. ₂ and the case where the base (BASE) is CH ₃ can be considered.

In this case, based on the van der Waals radii of the atomic groups constituting the head (HEAD) and the body (BODY), the atomic group constituting the head (HEAD) has a radius R _W = 0.2 (nm). The atomic group constituting the hemispherical body part (BODY) can be assumed to be a cylinder with a radius R _W = 0.2 (nm), and the contact angle θ _B = 105 ° of the body part (BODY) Become.

  Therefore, the height h from the base end of the body (BODY) to the tip of the head (HEAD) is h> [− 0.2 / (2 cos (105 °)) + 0.24 = 0.63] (nm ) Between the liquid infiltrated between the organic hydrophobic groups (in this case, water) and the hydroxyl groups (silanol groups) remaining on the surface of the porous body (in this case, silica gel), In order to prevent the formation of hydrogen bonds and satisfy h> 0.63 (nm), it is considered that the number of repetitions of the body part (BODY) should be set to m ≧ 3.

  As described above, in the colloidal damper of the present invention, first, the minimum thickness of the hydrophobic film capable of preventing the hydrogen bond formation between the liquid and the hydroxyl group is defined. As a result of examining the optimum thickness of the hydrophobic membrane to dissipate energy efficiently, and optimizing the thickness of the hydrophobic membrane in relation to the pore diameter of the hydrophobized porous material, the performance as a colloidal damper Was found to be improved, and the following configuration was devised.

That is, in the colloidal damper described below, the pore radius r of the hydrophobic porous body and the molecular chain length h of-(BODY) _m- (HEAD) are present on the pore surface of the hydrophobic porous body. Film thickness h _G , viscosity of the gas μ _G , viscosity of the liquid μ _L , and Knudsen number Kn = [0.5 h _G calculated based on the representative dimension L of the pores of the hydrophobic porous body for _{(1-μ G / μ L} ) / L], it is characterized in that there is a value satisfying the 0.034 ≦ Kn ≦ 0.119 (preferably Kn = 0.097).

  According to the colloidal damper configured as described above, the Knudsen number Kn satisfies 0.034 ≦ Kn ≦ 0.119 (preferably Kn = 0.097). The liquid slips and flows continuously on the pore surface of the material, and as a result, preferable dissipation energy and efficiency can be obtained, and the performance as a colloidal damper can be improved.

With regard to the Knudsen number, it was conventionally said that 0.01 <Kn <0.1 is good. However, the “Knusen number Kn” and “the film thickness h _{G of} the gas existing on the pore surface of the hydrophobized porous body, the gas viscosity μ _G , the liquid viscosity μ _L , and the pores of the hydrophobized porous body The relationship with the “representative dimension L” is not known. Therefore, in the past, optimizing the Knudsen number Kn itself has not always been easy. Also, the numerical range is 0.01 <Kn <0.1, and it was considered that a numerical range that is a little too wide or slightly shifted is effective. When the Knudsen number Kn is less than 0.034 and is close to 0.01, it becomes close to a state that can be regarded as a continuum in terms of fluid dynamics, and therefore the influence of slippage at the interface between the liquid and the pore surface is small. This is considered to be a factor that reduces the performance (efficiency) of the colloidal damper.

On the other hand, in the colloidal damper of the present invention, the film thickness h _{G of} the gas existing on the pore surface of the hydrophobized porous body, the gas viscosity μ _G , the liquid viscosity μ _L , and the hydrophobic porous body fine Since the Knudsen number Kn = [0.5 h _G (1−μ _G / μ _L ) / L] is calculated based on the representative dimension L of the hole, it is easy to optimize the Knudsen number Kn, and the numerical value thereof The pore radius r and-(BODY) _m- (HEAD) of the hydrophobized porous material so that the range satisfies a value satisfying 0.034 ≦ Kn ≦ 0.119 (preferably Kn = 0.097). Since the molecular chain length h is set, the performance as a colloidal damper can be improved beyond that in which the numerical range of the Knudsen number Kn is 0.01 <Kn <0.034.

More specifically, since the representative dimension L of the pores can be regarded as the pore radius r, the film thickness h _{G of} the gas existing on the pore surface of the hydrophobized porous body, the thickness h of the hydrophobic film, Knudsen number Kn = a _{[0.5h (1-μ G /} μ L) / r]. The gas viscosity μ _G and the liquid viscosity μ _L are constants determined according to the liquid used and the gas (for example, air) existing in the pores of the porous body. Therefore, the Knudsen number Kn is a value determined according to the pore radius r of the hydrophobized porous material and the molecular chain length h of-(BODY) _m- (HEAD). If the hole radius r is determined, the molecular chain length h of − (BODY) _m − (HEAD) is optimized so that 0.034 ≦ Kn ≦ 0.119 (preferably Kn = 0.097). On the other hand, if the molecular chain length h of-(BODY) _m- (HEAD) is determined, it is hydrophobized so that 0.034≤Kn≤0.119 (preferably Kn = 0.097). The pore radius r of the porous body can be optimized.

As a more specific example, for example, the liquid is water, the hydrophilic porous body is silica gel, the organic hydrophobic group is CH _{3 in} the head (HEAD), CH ₂ in the body (BODY), When the base (BASE) is CH ₃ , the pore radius r of the hydrophobized porous body and the molecular chain length h of — (BODY) _m — (HEAD) are the pore surface of the hydrophobized porous body. 0 thickness h _G of gas present, the head (hEAD) and equal to the height h of the columnar body formed of the barrel (bODY), viscosity mu _G of the gas is air viscosity on. 018 (mPa · s), the viscosity μ _L of the liquid is 1.002 (mPa · s) which is the viscosity of water, and the representative dimension L of the pores of the hydrophobic porous body is a pore radius r. For the Knudsen number Kn = [0.5h (1-0.018 / 1.002) /r=0.491h/r] calculated based on the assumption ≦ Kn ≦ 0.119 (preferably Kn = 0.097) need only be a value that satisfies.

For example, when the pore radius r of the hydrophobized porous material is 2.85 to 10 nm, the molecular chain length h of-(BODY) _m- (HEAD) is (0.034r / 0.491) ≤ When h ≦ (0.119r / 0.491), 0.034 ≦ Kn ≦ 0.119 is satisfied. Preferably, when the molecular chain length h of-(BODY) _m- (HEAD) is h = 0.097r / 0.491, Kn = 0.097 is satisfied.

That is, in the past, it was considered that the longer the molecular chain length, the more desirable, so even if the pore radius r is 2.85 to 10 nm, the molecular chain that satisfies h> 0.119r / 0.491. It is thought that there were many cases where the length h was set. However, in order to achieve hydrophobicity, even when an excessively long molecular chain length is effective, the decrease in pore diameter and pore surface area is suppressed. Considering this, a hydrophobic group having an excessively long molecular chain length is not always effective, and when the pore radius r is 2.85 to 10 nm, the molecular chain length h of-(BODY) _m- (HEAD) is ( 0.034r / 0.491) ≦ h ≦ (0.119r / 0.491) (preferably h = 0.097r / 0.491), the performance as a colloidal damper is improved. is there.

  By the way, in the above explanation, it has been explained on the assumption that the hydrophilic porous body is surface-treated with one kind of hydrophobic substance, but when the hydroxyl group remains on the surface of the porous body, The following configuration is also effective.

  That is, the hydrophobized porous body has a molecular weight higher than that of the first hydrophobic substance after surface-treating the hydrophilic porous body with the hydrophobic substance (hereinafter referred to as a first hydrophobic substance). The second hydrophobic substance is a surface treatment with a small second hydrophobic substance, and the second hydrophobic substance is a hydroxyl group present on the pore surface of the hydrophilic porous body by the first hydrophobic substance. After replacing hydrogen with the organic hydrophobic group (hereinafter referred to as the first organic hydrophobic group), the hydrogen in the hydroxyl group remaining on the pore surface of the hydrophilic porous body is converted into the second organic hydrophobic group. It may be a substitutable compound.

  The second organic hydrophobic group has a smaller molecular weight (molecular chain length) than the first organic hydrophobic group formed by the previous surface treatment. For example, as the second organic hydrophobic group, a trimethylsilyl group is used. It is possible to introduce.

  According to the colloidal damper configured in this way, since the residual hydroxyl groups can be reduced more than when the surface treatment is performed only with the first hydrophobic substance, the adverse effects due to the residual hydroxyl groups can be eliminated, Thereby, the performance as a colloidal damper can be improved.

Next, an embodiment of the present invention will be described with an example.
FIG. 2 is a schematic structural diagram for explaining the operation principle of the colloidal damper.
The colloidal damper 1 described below includes a container 7 constituted by a cylinder 3 and a piston 5, a mixture 15 of a liquid 11 and a hydrophobic porous body 13 contained in the container 7, and a pressure from the outside. 7 is provided with a transmission means 17 (piston rod) for increasing or decreasing the pressure acting on the mixture 15 by being transmitted to the mixture 15 in the cylinder 7.

In this embodiment, the piston 5 has a diameter D = 20 mm and a maximum stroke S _max = 50 mm, and the container 7 and the transmission means 17 are configured to apply a pressure of 120 MPa at maximum to the mixture 15 of the container 7. ing.

  In this embodiment, water (9 g in each experiment) is used as the liquid 11, and the hydrophobic porous body 13 is a surface treatment with a hydrophobic substance on silica gel, which is a hydrophilic porous body. Hydrophobized silica gel (4 g for each experiment) was used.

As the silica gel, four types of spherical silica gel particles (2r = 5.7, 7, 10, 20 nm) having an average particle diameter 2R of 20 μm and different average pore diameters 2r were used.
As the hydrophobic substance used for the surface treatment, four types of hydrophobizing agents capable of substituting hydroxyl groups on the silica gel surface with organic hydrophobic groups, trimethylchlorosilane, dimethylbutylchlorosilane, dimethyloctylchlorosilane, and dimethyloctadecylchlorosilane were used.

In the following description, focusing on the carbon number m + 1 of the molecular chain — (CH ₂ ) _m —CH ₃ = —C _{m + 1} H _{2m + 3 in} the organic hydrophobic group, the molecular chain — (CH ₂ ) Treatment for introducing an organic hydrophobic group containing _m- CH ₃ = -C _{m + 1} H _{2m + 3} is treated with Cm + 1 treatment (where m + 1 is a molecular chain-(CH ₂ ) _m -CH ₃ = -C _{m + 1} H _{2m + 3} carbon number). Specifically, surface treatment with trimethylchlorosilane is referred to as C1 treatment, surface treatment with dimethylbutylchlorosilane is referred to as C4 treatment, surface treatment with dimethyloctylchlorosilane is referred to as C8 treatment, and surface treatment with dimethyloctadecylchlorosilane is referred to as C18 treatment. In this embodiment, it is considered that the residual hydroxyl group can be reduced by introducing the second organic hydrophobic group having a smaller number of carbon atoms into the silica gel treated with C4 to C18. However, in order to avoid complicated explanation, hereinafter, silica gel that has been subjected to C4 to C18 treatment and then C1 treatment is simply referred to as silica gel that has been treated with C4 to C18.

In the present embodiment, the surface of the silica gel was hydrophobized by the following procedure using the four types of hydrophobizing agents as described above. Hereinafter, the case of the C4 process will be described as an example.
20 g of silica gel (manufactured by Fuji Silysia Chemical Co., Ltd .: trade name Super Micro Bead Silica Gel) was placed in a 500 ml separable flask, 400 ml of toluene and 12.0 g of dimethylbutylchlorosilane were added and refluxed for 3 hours. Thereafter, 17.0 g of trimethylchlorosilane was added and refluxed overnight. After refluxing, 1 L each of toluene and methanol was washed and vacuum dried at 70 ° C. to obtain a C4 treated product.

  In the case of C8 treatment, dimethyloctylchlorosilane was treated instead of dimethylbutylchlorosilane, and in the case of C18 treatment, dimethyloctadecylchlorosilane was treated instead of dimethylbutylchlorosilane. In the case of C1 treatment, the treatment was performed only with trimethylchlorosilane.

In order to evaluate the performance of the colloidal damper 1 configured as described above, the following experiment was performed.
Using a manual pump (not shown), the piston 5 is operated via the transmission means 17, and the piston 5 is slowly raised until the inside of the container 7 (temperature 20 ° C.) reaches a desired pressure (for example, 60 MPa). . Then, when the desired pressure is reached, the cargo is unloaded and the piston 5 is slowly returned to the initial position using a manual pump. This process is a single experiment. For each experiment, changes in the stroke S of the piston 5 and changes in the pressure p in the container 7 were measured. When this measurement result is graphed, as a typical example, a cycle in which hysteresis appears as shown in FIG. 3 is observed.

  The dissipated energy E of shock and vibration is equal to the mechanical piston work W, and the compression work is equal to the absorbed energy Ea that can be calculated by the following equation 1 in the actual cycle (FIG. 3).

Further, the dissipated energy E of impact or vibration is equal to the actual cycle area and can be calculated by the following formula 2.

The damper efficiency (ability to dissipate energy) η is generally defined by the following Equation 3.

In the present embodiment, the performance of the colloidal damper is evaluated based on the dissipated energy E and the efficiency η. When evaluating the effectiveness of a certain colloid (= mixture in the container 7), or when comparing a colloidal damper with a different type of damper, the dissipative energy and efficiency of the colloidal damper become parameters necessary for the evaluation.

  The above experiment was performed using five silica gels with different hydrophobizing agents (C1, C4, C8, C18, and non-surface-treated = hereinafter referred to as C0 treatment). Carried out. The pressure applied to the piston 5 was changed to five types (in the case of this embodiment, 25, 30, 35, 40, 60 MPa), and the above experiment was repeated a plurality of times at each pressure.

  First, in order to investigate the influence of pressure, four types of hydrophobized silica gel surface-treated with the above four types of hydrophobizing agents (both having an average pore diameter of 2r = 7 nm) were used, and the pressure applied to the piston 5 The data were arranged for the experimental results when the value was changed to 5 types (25, 30, 35, 40, 60 MPa in this embodiment). When repeating the experiment several times, the colloidal damper may show somewhat different behavior between the first experiment and the second and subsequent experiments, but since the behavior is generally stable after the second experiment, For the first experiment and the nth experiment, the dissipated energy E and the efficiency η were calculated, respectively, and the relationship between the dissipated energy E and the efficiency η and the pressure p was graphed. The results are shown in FIGS. 4 (a), (b), 5 (a), and (b).

From this experimental result, the following can be understood.
In the case of C1-treated silica gel, the nth hysteresis is lost and the dissipated energy and efficiency are very small. In the case of silica gel treated with C18, the dissipated energy is 35 J for the first time and 17.5 J for the nth time, whereas in the case of silica gel treated with C4, the dissipated energy is 60.2 J for the first time and 55 for the nth time. In the case of silica gel treated with .4J and C8, the dissipated energy is 52.3J for the first time and 48.9J for the nth time, and the dissipated energy of the colloidal damper 1 is the highest when C4 is treated.

  In addition, in the case of silica gel treated with C1 and silica gel treated with C18, the difference between the efficiency of the nth time and the efficiency of the first time becomes larger as the pressure increases, whereas the silica gel treated with C4 and the silica gel treated with C8 In this case, it can be seen that the efficiency at the n-th time is almost the same as the efficiency at the first time even when the pressure is increased.

  From the above, it can be said that the silica gel treated with C4 and the silica gel treated with C8 are hydrophobic porous bodies suitable for use in colloidal dampers, and each hydrophobizing agent used for C4 treatment and C8 treatment is It can be said that it is an excellent hydrophobizing agent. In addition, in the case of silica gel treated with C1, the n-th hysteresis is lost because the thickness of the hydrophobic film is not sufficiently secured in C1 treatment. It is possible to consider the reason that and form hydrogen bonds and water is not discharged reversibly.

Next, in order to investigate the influence of the length of the hydrophobically treated molecule, the results of experiments using five silica gels (C0 treated, C1 treated, C4 treated, C8 treated, C18 treated) having different hydrophobizing agents The data was organized. FIG. 6A and FIG. 6B show the first and nth hysteresis of the colloidal damper 1 at that time. Table 1 also shows the first and n-th dissipative energies E ₁ and E _n of the hysteresis of each material at a pressure of 60 MPa, and the ratio E _n / E ₁ , and the first and n-th efficiency η ₁ , η _n and its ratio η _n / η ₁ are shown.

From this experimental result, the following can be understood.

  Even in the case of non-hydrophobic treated hydrophilic surface silica gels (ie C0 treated silica gels), small hysteresis occurs, but this cycle is due to the compressibility of water, the elasticity of the silica gel, the influence of air, the cylinder piston This may be due to friction, seal / piston friction, etc. In the case of C0 treatment, since the surface is hydrophilic, water naturally enters the pores (at a pressure of 0 MPa) and is not discharged out of the pores. Therefore, the hysteresis of the colloidal damper 1 is reproducible. Disappear.

  Further, in the case of silica gel treated with C1, the first hysteresis (see FIG. 6A) is large, but the n-th hysteresis has disappeared (see FIG. 6B). In other words, in the case of silica gel treated with C1, the hysteresis of the colloidal damper 1 is not reproducible, and even though the colloidal damper 1 can dissipate the energy of the first impact, it dissipates the energy of the second and subsequent impacts. It is not possible to dissipate vibrational energy or to dissipate shock energy over and over again.

  In the case of silica gel treated with C4 to C18, the hysteresis of the colloidal damper 1 is reproducible. The first cycle includes a non-equilibrium phenomenon (for example, formation of a hydrogen bond between the remaining hydroxyl group and water), but the second and subsequent cycles (actual hysteresis) have the same magnitude. Therefore, if the silica gel is treated with C4 to C18, the colloidal damper 1 can dissipate the energy of the second and subsequent impacts and can dissipate the energy of vibration.

  Further, from FIG. 6A, the average compression pressure of the silica gel treated with C4 is larger than that of the silica gel treated with C1, and the average compression pressure of silica gel treated with C8 is larger than that of silica gel treated with C4. I can see that This shows that the average compression pressure increases as the molecular chain of the organic hydrophobic group is longer. This is considered to be related to the fact that the pore radius of the porous body becomes smaller as the molecular chain of the organic hydrophobic group becomes longer.

In addition, when the silica gel treated with C18 is seen, it can be seen that the n-th hysteresis is about half of the first hysteresis (E _n / E ₁ = 0.50; see Table 1). . However, the hysteresis of C4 and C8 is larger than that of C18 as a whole, and it can be seen that the n-th hysteresis is also close to the first hysteresis (E _n / E ₁ = 0.92, 0.93; see Table 1).

Considering that the dissipated energy E _n of the _n - _th cycle is maximized to E _n = 55.4 J (see Table 1), in the case of silica gel with a pore diameter of 2r = 7 nm, C4 treatment is the most suitable hydrophobic treatment method It is thought that.

Next, data on the results of experiments similar to the above in which each silica gel having an average pore diameter 2r of 5.7, 7, 10, and 20 nm and each hydrophobic treatment of C1, C4, C8, and C18 was combined was performed. Tidy. Table 2 shows the first and n-th dissipated energies E ₁ and E _n and their ratios E _n / E ₁ , the first and n-th efficiency η ₁ and η _n , and their ratios η _n / η _1. Indicates.

From Table 2, it can be seen that the silica-treated with C1 has a small n-th dissipated energy regardless of the average pore diameter, and the performance as a colloidal damper is not so high. Therefore, except for silica gel treated with C1, in FIG. 7 (a) and FIG. 7 (b), the horizontal axis represents the pore diameter 2r, and the vertical axis represents the first and n-th dissipated energies E ₁ and E _n . FIGS. 8A and 8B show graphs in which the horizontal axis represents the pore diameter 2r and the vertical axis represents the first and n-th efficiency η ₁ and η _n .

From these graphs, silica gel having an average pore diameter 2r of 7 nm is high in both the n-th dissipated energy E _n and the n-th efficiency η _{n when} treated with C4, and the silica gel has an average pore diameter 2r of 10 to 20 nm. It can be seen that both the n-th dissipated energy E _n and the n-th efficiency η _n of the C8-treated product increase. In addition, in the case of 2r = 20 nm, it can be seen that the nth dissipative energy of the C4 process is close to the nth dissipative energy of the C8 process.

From the above experimental results, it is difficult to achieve a sufficiently reproducible cycle in the C1 process, and it is possible to achieve a repeatable cycle in the C4, C8, and C18 processes. , C8, in C18 process, C4, C8 dissipated energy E _n it is the n-th than C18 treatment process, being able to n-th both high efficiency eta _n of between C4 process and C8 process, which is It can be seen that whether the n-th dissipative energy E _n and the n-th efficiency η _n can be made higher can vary depending on the average pore diameter 2r of the silica gel.

  Regarding the “C1 process, it is difficult to achieve a sufficiently reproducible cycle, and the C4, C8, and C18 processes can achieve a repeatable cycle” It is inferred that the cause is that the thickness of the hydrophobic film formed on the pore surface is too thin.

  More specifically, all of the hydrophobizing agents used in this embodiment substitute a hydroxyl group present on the surface of the silica gel with an organic hydrophobic group by a reaction represented by the following general formula (2).

This organic hydrophobic group forms a hydrophobic film on the silica gel surface, but the density of hydroxyl groups present on the silica gel surface is sufficiently high (for example, 2.3 to 4.8 hydroxyl groups per square nanometer are present). In this case, on the surface of the silica gel, the organic hydrophobic groups are arranged at such a density that can be regarded as a critical density (closest density state), and a brush-like structure is formed in which the organic hydrophobic groups are used as brush hairs. Moreover, all the hydroxyl groups present on the surface of the silica gel are not substituted with organic hydrophobic groups, and hydroxyl groups remain between the organic hydrophobic groups. Since this residual hydroxyl group is structurally sufficiently smaller than the organic hydrophobic group, it exists in the vicinity of the base portion between the organic hydrophobic groups arranged at a critical density, and remains without being replaced by the organic hydrophobic group. When considering the distance from the surface of the pore, the tip of the remaining hydroxyl group is almost at the same position as Si in the organic hydrophobic group, and the thickness of the hydrophobic film that inhibits the formation of hydrogen bonds with the remaining hydroxyl group is , - (CH ₂₎ molecular chain length of _{m -CH 3 = -C m + 1} H 2m + 3 and can be considered to be substantially the same.

Also, - (CH ₂₎ a molecular chain of _{m -CH 3 = -C m + 1} H 2m + 3 is constituted by atomic group CH ₃ in repetition and that end of the atomic group CH _2, a CH ₃ Head (HEAD), CH ₂ as body (BODY)-(BODY) _m- (HEAD) can be regarded as having a molecular structure, head (HEAD) and body (BODY) Based on the van der Waals radii of the atomic group constituting the atomic group constituting the head (HEAD), the atomic group constituting the body (BODY) is a hemispherical with a radius R _W = 0.2 (nm) It can be assumed that the columnar shape has a radius R _W = 0.2 (nm).

  When the colloidal damper 1 is formed using a hydrophobic silica gel having a hydrophobic membrane having such a brush-like structure on the surface and a hydrophilic liquid, for example, water, water is contained in the pores due to pressurization. Microscopically, the water that has entered the pores also enters between the organic hydrophobic groups forming the brush-like structure more microscopically.

  On the other hand, since water has a low affinity for organic hydrophobic groups and the contact angle with respect to the surface of organic hydrophobic groups is greater than 90 degrees, the surface tension of water acts to discharge water from between the organic hydrophobic groups, Furthermore, it acts to discharge water from the pores whose surfaces are covered with organic hydrophobic groups.

  However, there is a residual hydroxyl group between the organic hydrophobic groups in the pores as described above, and when this residual hydroxyl group and water form a hydrogen bond, water is not discharged from between the organic hydrophobic groups even under a reduced pressure condition. May not be reversibly discharged out of the pores, which may be a factor that degrades the performance of the colloidal damper.

Therefore, in order to inhibit the formation of such hydrogen bonding, - (CH ₂₎ a _{m -CH 3 = -C m + 1} H 2m + 3 of molecular chain length, and penetration liquid between organic hydrophobic groups remaining It is considered that the length should be longer than the extent that the hydroxyl group does not form a hydrogen bond.

As already described, FIG. 1 is a diagram in which a model of an organic hydrophobic group is shown on the left side and a graph of the energy state E _C of water that has entered between the organic hydrophobic groups is shown on the right side. Model of organic hydrophobic groups drawn on the left side, the head (HEAD) and the body portion based on the van der Waals radii of atomic group forming a (BODY), the head (HEAD) the radius R _W of hemispherical, barrel (bODY) a has become cylindrical and the assumed model of radius R _W, the vertical axis represents the distance from the head side of the organic hydrophobic groups. In the graph drawn on the right side, the horizontal axis indicates the height of the energy E _C , and there are stable points with low energy states at two points, point B and point D, between point B and point D. This indicates that there is a point C as an energy barrier.

When the external pressure p is smaller than the average compression (adsorption) pressure (for example, in FIG. 6A, in the case of C1, the average compression (adsorption) pressure is about 20 MPa), the liquid does not enter the pores. When the external pressure p becomes equal to the average compression (adsorption) pressure, the liquid enters the pores. At this time, since the energy state at the point B is smaller than the energy state at the point A, when the liquid enters the pores, the organic hydrophobic group reaches the position of the point B while contacting the head of the organic hydrophobic group. It will intrude in between. When the pressure p from the outside becomes larger than the average compression (adsorption) pressure (for example, in FIG. 6, the maximum pressure from the outside is 60 MPa), the liquid is forcibly pushed between the organic hydrophobic groups. When the energy required to exceed the C point is given from the outside, the liquid further penetrates into the back between the organic hydrophobic groups. The problem is how far the liquid penetrates between the organic hydrophobic groups. Since the G point has the same energy state as the C point, the liquid first penetrates between the organic hydrophobic groups up to the G point. Furthermore, when energy is input to the system from the outside, the energy state becomes larger than the point G, and it is generally considered that the liquid can penetrate to the point I. However, the relationship between the energy state E _{C of the} liquid and the equivalent contact angle θ is E _C = −cos θ, and the equivalent contact angle θ is obtained from a mathematical condition that the cosine function (cos) is smaller than 1 (± cos θ ≦ 1). And the y-axis relationship of FIG. 1, an inequality of y ≦ −R _W / (2 cos θ _B ) can be obtained. Therefore, the liquid cannot penetrate below the H point (y> −R _W / (2 cos θ _B )). This can be said to be correct because the energy states at point H and point A are equal in FIG.

  On the other hand, when the external pressure stops working, the liquid having low affinity for the organic hydrophobic group is discharged from between the organic hydrophobic groups due to the surface tension of the liquid. However, in order to reversibly enter and discharge the liquid, it is necessary to prevent the liquid that has entered between the organic hydrophobic groups up to the H point from forming a hydrogen bond with the remaining hydroxyl group present on the base side (BASE). .

Here, water that has penetrated to the point H may form hydrogen bonds when approaching 0.24 (nm) with respect to the hydroxyl group (reference: Pauling, L., The Chemical Bond. A Brief Introduction to Modern Structural Chemistry, Cornell University Press, New York, 1967). From these facts, in order to prevent water that has penetrated to the H point from forming a hydrogen bond with the remaining hydroxyl group present on the base side, the molecular chain length h of-(BODY) _m- (HEAD) is set to h It can be said that> [− R _W / (2 cos θ _B ) +0.24] (nm) is preferable.

In this embodiment, the organic hydrophobic group has van der Waals of the atomic group constituting the head (HEAD) and the body (BODY) because the head (HEAD) is CH ₃ and the body (BODY) is CH _2. Based on the radius, the atomic group constituting the head (HEAD) is a hemisphere having a radius R _W = 0.2 (nm), and the atomic group constituting the body (BODY) is a radius R _W = 0.2 (nm). ), And the contact angle θ _B of the body (BODY) is 105 °.

Therefore, the height h from the base end of the body (BODY) to the tip of the head (HEAD) is h> [− 0.2 / (2 cos (105 °)) + 0.24 = 0.63] (nm ), It is possible to prevent hydrogen bonds from being formed between the water that has entered between the organic hydrophobic groups and the hydroxyl groups remaining on the surface of the hydrophobic silica gel. In order to satisfy h> 0.63 (nm), the number of repetitions m of the body (BODY) is m ≧ 3, that is, molecular chain − (CH ₂ ) _m —CH ₃ = −C _{m + 1} H _2m It is considered that the number of carbons in ₊₃ (m + 1) should be set to (m + 1) ≧ 4, which is in good agreement with the fact that repeatability appears in the hysteresis of silica gel treated with C4 to C18. .

In addition, "in the C4, C8, C18 processing, it can be more of C4, C8 process is both high n-th of the dissipated energy E _{n, n-th} of efficiency η _n than the C18 processing" For, C18 processing In this case, an excessively thick hydrophobic membrane is formed, which leads to a decrease in pore diameter and pore surface area. As a result, it is considered that the performance of the colloidal damper may be adversely affected.

Furthermore, regarding “the C4 treatment and the C8 treatment, which can increase the n-th dissipative energy E _n and the n-th efficiency η _n can vary depending on the average pore diameter 2r of silica gel”, the Knudsen number When the evaluation by Kn is performed, it is possible to explain in good agreement with the experimental results.

The Knudsen number Kn is based on the film thickness h _{G of} the gas existing on the pore surface of the hydrophobized silica gel, the gas viscosity μ _G , the liquid viscosity μ _L , and the representative dimension L of the pores of the hydrophobized porous body. Kn = [0.5 h _G (1−μ _G / μ _L ) / L] can be calculated. Here, the representative dimension L of the pores is equal to the pore radius r, and the film thickness h _G of the gas existing on the pore surface of the hydrophobized porous body can be regarded as being equal to the thickness h of the hydrophobic film. , the Knudsen number Kn = [0.5h (1-μ G / μ L) / r]. In the case of the present embodiment, the gas viscosity μ _G is 0.018 (mPa · s) that is the viscosity of air, and the liquid viscosity μ _L is 1.002 (mPa · s) that is the viscosity of water. Therefore, the Knudsen number Kn = 0.5h (1−0.018 / 1.002) /r=0.491h/r.

The hydrophobic film thickness h - (CH _{2) m} is regarded _{-CH 3 = -C m + 1 H} 2m + 3 of molecular chain length and, C4, C8, C18 and the thickness h by the processing, the average pore diameter When the Knudsen number Kn is calculated for the combination of 2r = 5.7 to 20 nm, the results shown in Table 3 below are obtained. From Table 2, it was found that the silica treated with C1 has a small n-th dissipative energy regardless of the average pore diameter, and the performance as a colloidal damper is not so high. The results for the C4, C8, C18 treated silica gel were summarized, except for the treated silica gel.

From the results in Table 3, the combination of the average pore diameter 2r = 5.7 nm and the C4 treatment (the most effective treatment in the case of the smallest pore) gives the Knudsen number Kn = 0.119, which is the average It can be seen that the combination of the pore diameter 2r = 20 nm and the C8 treatment (the most effective treatment in the case of the largest pore) gives the Knudsen number Kn = 0.059. Furthermore, it can be seen from FIG. 7B that when 2r = 20 nm, the nth dissipation energy of the C4 treatment is close to the nth dissipation energy of the C8 treatment. Therefore, in order to obtain the minimum limit of Knudsen number, the combination of average pore diameter 2r = 20 nm and C4 treatment gives Knudsen number Kn = 0.034, and the appropriate Knudsen number range is 0.034 ≦ Kn ≦ 0. 119. Further, when the average pore diameter 2r = 10 nm and the average pore diameter 2r = 20 nm, C8 is the most effective treatment, but the values of Knudsen number Kn = 0.118 and Knudsen number Kn = 0.599 are An appropriate Knudsen number range 0.034 ≦ Kn ≦ 0.119 falls. Further, from FIG. 7B, in order to maximize the dissipation energy at the n-th time, the combination of the average pore diameter 2r = 7 nm and the C4 treatment is optimal, and the optimal Knudsen number is Kn = 0.097. I understand that This result partially coincides with the conventional range of Knudsen number Kn, 0.01 <Kn <0.1, which has been said conventionally, but the Knudsen number range of this patent is 0.034 ≦ Kn ≦ 0.119. Can be seen to be narrower and slightly off.

  From the above results, it can be inferred that the preferred range of Knudsen number Kn, 0.01 <Kn <0.1, which has been said so far, is slightly too large and the numerical range is slightly shifted. A more preferable range of Kn is considered to be a value satisfying 0.034 ≦ Kn ≦ 0.119.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said specific one Embodiment, In addition, it can implement with a various form.
For example, in the above embodiment, as a specific example of the molecular chain − (BODY) _m − (HEAD) in the organic hydrophobic group, the molecular chain − (CH ₂ ) _m —CH ₃ = −C _{m + 1} H _{2m + 3} Although exemplified, a hydrophobic body having a similar brush-like structure may be formed, and the body (BODY) and the head (HEAD) made of other atomic groups may be used. As such a combination of the body (BODY) and the head (HEAD), for example, [(BODY), (HEAD)] = [CF ₂ , CF ₃ ], [OSi (CH ₃ ) ₂ , OSi ( Combinations such as CH ₃ ) ₃ ], [OSi (CF ₃ ) ₂ , OSi (CF ₃ ) ₃ ] can be considered.

Further, although CH ₃ is shown as the base (BASE) in the organic hydrophobic group, it may be an atomic group that does not become an obstacle to forming a hydrophobic film having a brush-like structure. For example, — (BODY) _m — An alkyl group having 1 to 3 carbon atoms having a shorter molecular chain length than (HEAD) or a phenyl group can be considered.

  Furthermore, in the above embodiment, after the C4, C8, and C18 treatments, the C1 treatment is further performed. However, whether or not the C1 treatment is performed is arbitrary, and the C4, C8, and C18 treatments are sufficiently hydrophobic. If the conversion is achieved, the C1 process may be omitted. In addition, this secondary C1 treatment is a treatment for hydroxyl groups that could not be hydrophobized by the C4, C8, C18 treatment as the previous step, so if a hydrophobizing agent having a smaller molecular weight than the previous step is used, A corresponding effect can be expected.

It is the figure which wrote together the graph which shows the energy state of the liquid which contacted the model of the organic hydrophobic group, and the organic hydrophobic group. It is a structural diagram showing a schematic structure of a colloidal damper. It is a graph which illustrates the relationship between the stroke of a piston, and the pressure in a container. It is a graph which shows the relationship between the dissipation energy E and the pressure p. It is a graph which shows the relationship between efficiency (eta) and the pressure p. It is a graph which shows the difference in the hysteresis by the difference in the length of a hydrophobic treatment molecule | numerator. It is a graph which shows the relationship between the pore diameter 2r and the dissipation energy E. It is a graph which shows the relationship between pore diameter 2r and efficiency (eta).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Colloidal damper, 3 ... Cylinder, 5 ... Piston, 7 ... Container, 11 ... Liquid, 13 ... Hydrophobized porous body, 15 ... Mixture, 17 ... -Transmission means.

Claims (7)

By treating the surface of the hydrophilic porous body with a hydrophobic substance, the hydrophobic porous body modified to exhibit hydrophobicity, the hydrophilic liquid, the liquid, and the hydrophobic porous body A container for containing the mixture, and a transmission means for increasing or decreasing the pressure acting on the mixture by transmitting the pressure from the outside to the mixture in the container, the pressure from the outside acting on the transmission means Accordingly, when the pressure acting on the mixture increases, the liquid penetrates into the pores of the hydrophobic porous body, and the external pressure acting on the transmission means is attenuated as the liquid enters. A colloidal damper,
The hydrophobic substance is a compound capable of replacing hydrogen in a hydroxyl group present on the pore surface of the hydrophilic porous body with an organic hydrophobic group,
The organic hydrophobic group is represented by the following general formula (1), and the head (HEAD) has a radius R _W based on the van der Waals radius of the atomic group constituting the head (HEAD) and the body (BODY). hemispherical, it has become barrel portion (bODY) in a cylindrical shape and can assume molecular structure of radius _{R W, - (bODY) m} - molecular chain length h of (HEAD) is, the barrel of (bODY) A colloidal damper, characterized in that h> [− R _w / (2 cos θ _B ) +0.24] (nm) in relation to the contact angle θ _B.
The liquid is water;
The hydrophilic porous body is silica gel;
The organic hydrophobic group includes the head (HEAD) of CH ₃ , the body (BODY) of CH ₂ , and the base (BASE) of CH ₃ , and constitutes the head (HEAD) and body (BODY). Based on the van der Waals radius of the atomic group, the head (HEAD) has a hemispherical shape with a radius R _W = 0.2 (nm) and the body (BODY) has a cylindrical shape with a radius R _W = 0.2 (nm). The molecular chain length h of − (BODY) _m − (HEAD) is related to the contact angle θ _B = 105 ° of the body (BODY), and h> [− The colloidal damper according to claim 1, wherein the colloidal damper has a value satisfying 0.2 / (2cos (105 °)) + 0.24 = 0.63] (nm). The pore radius r of the hydrophobic porous body and the molecular chain length h of-(BODY) _m- (HEAD) are the film thickness h _{G of} the gas existing on the pore surface of the hydrophobic porous body, the gas viscous mu _G, the viscosity of the liquid mu _L, Knudsen number Kn = (0.5h _G calculated based on the typical dimension L of the pores of the hydrophobic porous body _{(1-μ G / μ L} ) / The colloidal damper according to claim 1 or 2, wherein L) is a value satisfying 0.034≤Kn≤0.119. The liquid is water;
The hydrophilic porous body is silica gel;
The organic hydrophobic group, said head (HEAD) is CH _3, said barrel (BODY) is CH _2, wherein the base (BASE) is CH _3,
The pore radius r of the hydrophobic porous body and the molecular chain length h of-(BODY) _m- (HEAD) are the film thickness h _G of the gas existing on the pore surface of the hydrophobic porous body, It is equal to the height h of the columnar body consisting of the head (HEAD) and the body (BODY), the gas viscosity μ _G is 0.018 (mPa · s) that is the viscosity of air, and the viscosity μ of the liquid is _L is 1.002 (mPa · s), which is the viscosity of water, and the Knudsen number Kn is calculated based on the assumption that the representative dimension L of the pores of the hydrophobic porous body is the pore radius r. = [(0.5h (1−0.018 / 1.002) / r) = (0.491h / r)], the value satisfies 0.034 ≦ Kn ≦ 0.119. 4. The colloidal damper according to claim 3, wherein The hydrophobized porous body has a pore radius r of 2.85 to 10 nm, and a molecular chain length h of-(BODY) _m- (HEAD) is (0.034r / 0.491) ≤h≤ (0 119r / 0.491). The colloidal damper according to claim 4, wherein The hydrophobic porous body has a molecular weight smaller than that of the first hydrophobic substance after the hydrophilic porous body is surface-treated with the hydrophobic substance (hereinafter referred to as a first hydrophobic substance). A surface treated with a second hydrophobic substance,
The second hydrophobic substance converts hydrogen in a hydroxyl group present on the surface of the pores of the hydrophilic porous body by the first hydrophobic substance into the organic hydrophobic group (hereinafter referred to as the first organic hydrophobic group). The compound in which hydrogen in the hydroxyl group remaining on the pore surface of the hydrophilic porous body after substitution with a second organic hydrophobic group can be substituted. The colloidal damper according to any one of 5 above. The colloidal damper according to claim 6, wherein the second organic hydrophobic group is a trimethylsilyl group.