KR102073392B1 - Actuator comprising heat diffusing material, method for preparing the same and use of the same - Google Patents

Abstract

At least two polymer unit fibers, wherein two or more of the polymer unit fibers having a torsion structure or twisted structure, comprising a heat dissipating material on the surface of the torsional structure or the twisted structure, a manufacturing method thereof And uses thereof.

Description

Actuator including a heat-dissipating material, a method for manufacturing the same, and a use including the same {ACTUATOR COMPRISING HEAT DIFFUSING MATERIAL, METHOD FOR PREPARING THE SAME AND USE OF THE SAME}

The present invention relates to a driver comprising a heat dissipating material, a method of manufacturing the same, and a use including the same.

Actuators (actuators) that can be utilized as artificial muscles include twisted-coiled polymer actuators, shape memory alloy actuators, and the like, which can be driven by heat. In general, it is contracted by heating by Joule heating, and then cooled and restored to its original length. The heat driven driver can determine the overall drive speed depending on the cooling performance. Conventionally, there is a problem that the driving speed is significantly reduced because there is no cooling method.

Recently, a driver has been reported that improves the driving speed by circulating water on the surface of the actuator, but an additional tube is needed to circulate around the actuator with water, and a device that circulates water from the outside is bulky and energy-consuming. Bigger, there was a limit to be used as artificial muscle.

In particular, coiled or torsional actuators are made by twisting polymer fibers, and the actuator has a driving mechanism that stretches to its original length when heated and shrinks when cooled, and requires a coating method that does not interfere with such driving characteristics. Do.

Background art of the present invention is disclosed in Korea Patent Publication No. 10-2017-0039849.

The problem to be solved by the present invention is to provide a driver with improved driving speed, in particular cooling rate.

Another problem to be solved by the present invention is to provide a driver that can ensure the driving characteristics by heating and cooling is equal or more compared with before including the heat radiation material even if the heat radiation material.

Another problem to be solved by the present invention is to provide a driver that can ensure that the driving characteristics by heating and cooling is equal to or higher than before including the heat radiation material even if the amount of coating of the heat radiation material.

Another problem to be solved by the present invention is to provide a manufacturing method capable of manufacturing the actuator of the present invention and its use.

The actuator of the present invention may include two or more polymer unit fibers, two or more of the polymer unit fibers may have a torsion structure or a twist structure, and may include a heat dissipation material on the surface of the torsion structure or the twist structure. .

The torsional structure or the twisted structure may include pores surrounded therein by the unit fibers, and the pores may not include a heat radiation material.

The heat dissipating material may not form a torsion structure or a twisted structure.

The heat radiation material may form a heat radiation layer.

The heat dissipation layer may be formed of a heat dissipation layer composition including the heat dissipation material and the silicone resin.

The silicone resin may comprise polydimethylsiloxane.

The heat dissipating material is a solid phase, and may include one or more of graphene, graphite, carbon nanotubes, metal nanowires, and metal nanoparticles.

Silver polymer may be coated on the surface of the polymer unit fiber.

The driver may be heat driven.

The manufacturing method of the actuator of the present invention comprises at least two polymer unit fibers, forming a torsion structure or twisted structure for at least two of the polymer unit fibers, and coating the heat radiation material on the torsion structure or twisted structure It may include.

The artificial muscle of the present invention may comprise the driver of the present invention.

The present invention provides a driver with improved driving speed, in particular cooling rate.

The present invention provides a driver capable of ensuring equal or more driving characteristics by heating and cooling compared to before including the heat radiating material, even if the heat radiating material is included.

The present invention provides a driver capable of securing an equal or more driving characteristic by heating and cooling compared to before including the heat radiating material even if the amount of coating of the heat radiating material is large.

The present invention provides a manufacturing method and its use which can manufacture the actuator of the present invention.

1 is a schematic diagram of a driver having a twisted structure among drivers according to an embodiment of the present invention.
FIG. 2 is a SEM photograph of the actuator of the twist structure before and after the coating of graphene in Example 1 and the driver of the twist structure after coating.
Figure 3 is a graph evaluating the driving time for the actuator of the twist structure before and after the coating of graphene in Example 1.
4 is a SEM photograph and a driver of the twisted structure manufactured in Example 2;
Figure 5 is a graph evaluating the driving time for the actuator of the twist structure before and after the coating of graphene in Example 2.
FIG. 6 is a twisted-shape actuator manufactured in Example 3 and an SEM photograph thereof. FIG.
7 is a SEM photograph and a driver of the twisted structure manufactured in Example 4. FIG.
Figure 8 is a graph evaluating the driving time for the actuator of the twist structure before and after the coating of graphene in Example 4.
9 is a SEM photograph and a driver of the twisted structure manufactured in Example 5. FIG.
10 is a SEM photograph of the twisted structure after graphene coating in Example 6
FIG. 11 is a graph evaluating driving time for the actuator of the twisted structure before and after coating of graphene in Example 6. FIG.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention.

Actuators having a twist or coil structure have a drive mechanism that contracts upon application of heat and returns to its original length when cooled. However, there is a problem in that the cooling speed is significantly slowed during the cooling of the heated driver, the overall driving speed is not fast.

Thus, the present inventors confirmed that the drive speed is remarkably improved by including the heat dissipation material on the surface of the torsion structure or the twist structure while having the torsion structure or the twist structure by manufacturing the driver by the manufacturing method of the driver of the present invention described below. This invention was completed.

Hereinafter, the driver of an embodiment of the present invention will be described.

The actuator of an embodiment of the present invention is a soft actuator, and includes two or more polymer unit fibers, and two or more of the polymer unit fibers have a torsion structure or a twist structure, and the torsion structure or the twist structure The surface of the structure may comprise a heat dissipating material. Therefore, the driver of the present invention can include a heat dissipating material on the surface of the torsion structure or the twist structure, which can significantly improve the driving speed while preventing the shrinkage caused by heat of the driver and the restoration by cooling. At this time, the "drive speed" is a value calculated by calculating the speed until the drive is restored to its original state when it is contracted by heating at a predetermined temperature and then cooled.

Such a driver of the present invention may be manufactured by the method described below, which will be described in detail below.

As described above, the actuator of the present invention may include two or more polymer unit fibers forming a torsion structure or a twist structure, but include a heat dissipation material on the torsion structure or the surface of the twist structure. This will be described in detail with reference to FIGS. 1 and 2. 1 is a schematic diagram of a driver having a twisted structure among drivers according to an embodiment of the present invention. 2 is a SEM photograph of the surface of the driver after coating the heat radiation material to the driver having a twisted structure of the driver according to an embodiment of the present invention.

Referring to FIG. 1, a driver having a twisted structure of the present invention may distribute heat dissipation material on the surface of the twisted structure. This can also be seen when referring to FIG. 2. Referring to FIG. 2, the heat radiation material is distributed on the surface of the twisted structure. Through this, the driver of the present invention can significantly improve the driving speed.

Preferably, the driver having the twisted structure of the present invention may include heat dissipating material only on the outermost surface of the twisted structure with respect to the center of the twisted structure in the longitudinal direction of the twisted structure. In such a case, the driver having the twisted structure of the present invention includes a void surrounded by the unit fibers therein, and the void does not include a heat dissipating material. In particular, the actuator of the present invention can be secured without voids even when shrinked by heating. Therefore, the driving speed can be remarkably improved without disturbing the repetitive driving by heating / cooling the driver.

In one embodiment, in the actuator of the present invention, the heat dissipating material may be formed only on the outermost surface of the torsion structure or the twisted structure, but may not form the twisted structure or the twisted structure along the longitudinal direction of the polymer unit fiber. In this case, however, the heat dissipation material may be in a solid phase. Thus, the heat dissipation material may have no effect on the driving of the driver by repetition of heating and shrinking of the driver while improving the driving speed of the driver.

Hereinafter, the structure of the driver of this invention is demonstrated in detail.

The driver includes two or more polymer unit fibers. The driver of the present invention may include a case in which two or more polymer unit fibers form a twisted structure or a twisted structure alone or when a plurality of these fibers are arranged to form a bundle.

The two or more polymer unit fibers may be formed of a polymer commonly used in the driver field. For example, the polymer may be nylon, polyurethane, or the like as a flexible, transparent or opaque material.

The two or more polymer unit fibers are fibers having a circular or amorphous cross section and having a predetermined length, and the polymer unit fibers may be in the form of nanofibers or microfibers having a diameter of several nanometers or several micrometers.

The actuator may be formed by the polymer unit fiber alone, or a conductive material may be coated on the polymer unit fiber surface. This can increase the heating rate of the driver by applying a current to the unit fiber, and can promote heat diffusion to improve the heating characteristics. The conductive material may include silver, gold, copper, aluminum, and the like, and preferably may include silver. Coating the conductive material on the surface of the polymer fiber can be applied to conventional methods known to those skilled in the art. The conductive material may be in the form of a plated film, nanoparticles, nanowires, three-dimensional material, but is not limited thereto.

At least two polymer unit fibers constituting the actuator form a torsional structure or a twisted structure. The torsional structure or twisting structure has a completely different shape from the simple straight actuator without torsion or twisting. As used herein, the term "torsional structure" means a structure in which the number of twists applied is not less than 4000 and not more than 8000, although it depends on the diameter of the polymer unit fibers. As used herein, "twist structure" means a structure in which the number of twists applied is generally greater than 1000 and less than 4000 turn / m, although it depends on the diameter of the polymer unit fibers.

The heat dissipating material is not particularly limited, but may be bonded to the polymer unit fiber surface by van der waals force or other chemical bond. As a result, the heat radiation material is strongly bonded to the surface of the polymer unit fiber, thereby increasing the reliability of the driver because it does not affect the driving speed and the driving even when repeatedly occurring during contraction and restoration of the driver.

The heat dissipating material is not limited in shape, but it is preferable to use a solid phase heat dissipating material. This can produce a heat dissipation effect and when the heat dissipation material is a liquid, the heat dissipation material of the liquid may penetrate into the voids in the twisted structure or torsion structure during the manufacturing process of the driver may affect the driving, there may be no such problem. The solid phase may include, but is not limited to, one or more of flake type, foam type, and nanotube type.

As a solid heat dissipating material, it may include one or more of carbon materials, such as graphene, graphite (graphite), carbon nanotubes. Graphene, graphite may comprise a single layer or multiple layers of graphene. The carbon nanotubes may include one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes. The solid heat dissipating material is not limited to the carbon material, and may include metal nanowires, metal fibers, metal nanoparticles, and the like.

The heat dissipating material may be formed in the torsion structure or the twisted structure alone, or may be formed in the torsion structure or the twisted structure by forming a heat dissipation layer. In this case, the heat dissipation layer is formed of a heat dissipation layer composition including a heat dissipation material and a silicone resin, so that the heat dissipation material can be more stably bonded to the polymer unit fiber, and when the silicone resin has flexibility, the flexibility of the driver is increased. Can be. The silicone resin is not particularly limited but may include polyalkylsiloxanes including polydimethylsiloxna and the like. The heat dissipating layer composition may further include conventional additives that may provide additional functions to the driver.

The actuator of the present invention may be a heat driven type that is contracted by heating and then restored when cooled. Specifically, the operating temperature of the actuator of the present invention may be from 35 ℃ to 120 ℃, which will vary depending on the type of polymer. In the above range, when including the heat radiation material of the present invention may have an effect of improving the drive speed.

Hereinafter, a method of manufacturing the driver of one embodiment of the present invention will be described.

The method of manufacturing an actuator of an embodiment of the present invention includes two or more polymer unit fibers and forms a torsion structure or a twisted structure with respect to two or more of the polymer unit fibers, and the heat dissipation material is applied to the torsion structure or the twisted structure. Coating may be included.

First, a torsional or twisted structure is formed for two or more of the two or more polymer unit fibers. The method of forming the twisted structure on the polymer unit fiber is by a conventional method known to those skilled in the art. For example, both ends of the polymer unit fibers may be rotated in opposite directions, or both ends may be fixed, but only the opposite ends may be rotated. That is, it is not limited as long as it can give twist or twist using two polymer unit fibers. Depending on the number of twists, it may be divided into a twisting structure or a twisting structure.

The heat dissipating material is as described above.

The coating method is not particularly limited. After the heat radiation material itself is synthesized by chemical vapor deposition, the synthesized film heat radiation material may be coated on the driver. Alternatively, the heat dissipating material may be mixed with a predetermined solvent to increase the coatability and / or coating property of the heat dissipating material. The solvent may include a conventional solvent which may not dissolve the heat dissipating material. For example, water, alcohols such as ethanol, and nonalcoholic organic solvents such as methyl 2-pyrrolidone may be used. The content of the heat dissipating substance in the solvent may be adjusted in consideration of the coating property. Alternatively, the coating may be performed using a heat dissipating layer composition comprising a heat dissipating substance and a silicone resin. The coating method is not particularly limited and may be dip coating, spray coating or the like.

The manufacturing method of the present invention may further comprise the step of drying after coating the heat radiation material. The drying temperature and drying time are not particularly limited.

The manufacturing method of the driver of the present invention may include heating the torsional structure or the twisted structure to shrink the torsional structure or the twisted structure, and coating a heat dissipation material on the contracted torsional or twisted structure. Through this, the torsional or twisted structure is first heated to shrink and then coated with a heat dissipating material to significantly improve the driving speed, while driving characteristics of the shrinkage and restoration by heating and cooling of the actuator are the same as before the heat dissipating material is coated. I can make it come out. In particular, when the thickness of the heat dissipating material layer is increased or the content of the heat dissipating material is increased to increase the heat dissipation effect, the driving characteristics may be deteriorated due to an increase in the rigidity of the driver. However, the manufacturing method of the present invention eliminates problems such as deterioration of driving characteristics even when the thickness of the heat dissipating material layer is increased.

The torsional or twisting structure can be heated to shrink the torsional or twisting structure. In this case, the contraction refers to contraction in the longitudinal direction of the twisted structure or the twisted structure, that is, in the longitudinal direction of the polymer unit fiber. Shrinkage, which is a degree of shrinkage, may be represented by the following Equation 1 and the shrinkage may be 5% to 30%, preferably 10% to 30%. Even if a small amount of heat dissipating material is used in the above range, the driving speed may be improved and the driving characteristics of the final manufactured driver may not be affected.

<Equation 1>

Shrinkage = (A-B) / A x 100

(Equation 1, A is the maximum length of the actuator before contraction (unit: mm)

B is the maximum length of the actuator after shrinkage in mm

In one embodiment, the driver can be heated at a drive temperature of 40 ° C. to 120 ° C., preferably 100 ° C. In the above range, the coating of the heat dissipating material can be well done.

Hereinafter, the use of the driver of an embodiment of the present invention will be described.

The driver of an embodiment of the present invention can be used for artificial muscles, sensors, and the like, but is not limited thereto.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, the following examples are provided to help the understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Example  One

Silver was coated on the surface of each of the two nylon fibers, and both ends of the two nylon fibers were rotated in opposite directions to form a twisted structure. Graphite nanoplatelets were added to NMP (N-methyl-2-pyrrolidone), mixed, sonicated, separated into thinner graphene, and filtered to obtain graphene. The obtained graphene was dispersed in a mixed solution of water and ethanol to prepare a solution including a heat radiation substance. The solution containing the heat radiation material prepared above was coated using a spray gun. The driver manufactured therefrom is shown in FIG. 2. In this embodiment the amount of coated heat dissipating material is about 1.6 mg and the weight of the actuator is about 250 mg. The result of taking the surface of the manufactured driver by SEM is shown in FIG. Referring to Figure 2, it can be seen that the graphene is well attached to the nylon fiber. A weight of 500 g was applied to the lower end of the manufactured driver, a load was applied thereto, and the driving time of the driver was measured while repeating the application of a current, heating to 100 ° C., cutting off the current, and cooling to 35 ° C. As a result, it is shown in FIG. Referring to FIG. 3, the total driving time of the actuator after graphene coating was significantly shortened, and the total driving time of about 31% was reduced.

Example  2

In Example 1, a driver was manufactured in the same manner except that a polydimethylsiloxane resin was further included with graphene to prepare a solution including a heat dissipating material, and a driver was used to prepare a solution. At this time, graphene was included in 25% by volume compared to polydimethylsiloxane. The driver manufactured therefrom is shown in FIG. 4. The result of taking the surface of the manufactured driver by SEM is shown in FIG. Referring to Figure 4, it can be seen that the graphene is well attached to the nylon fiber. The driving time was measured in the same manner as in Example 1 for the manufactured driver. As a result, it is shown in FIG. Referring to FIG. 5, the total driving time of the actuator after graphene coating is significantly shortened, and the total driving time of about 37% is reduced.

Example  3

In Example 1, a driver was manufactured in the same manner except that a carbon nanotube and a polydimethylsiloxane resin were mixed with a solution containing a heat dissipating material and the actuator was manufactured using the same. At this time, the carbon nanotubes were included in 0.1% by weight compared to the polydimethylsiloxane. The driver manufactured therefrom is shown in FIG. 6. 6 shows the results of SEM observation of the surface of the manufactured actuator. Referring to Figure 6, it can be seen that the graphene is well attached to the nylon fiber. When the driving time was evaluated in the same manner as in Example 1 with respect to the manufactured driver, the driving time was reduced by about 12% compared to before the coating.

Example  4

Three-dimensional graphene foam was used as a heat dissipating material. Graphene foam was prepared by synthesizing multilayer graphene on nickel foam by chemical vapor deposition to form a three-dimensional structure and etching nickel. Using this, a driver was manufactured in the same manner as in Example 1. The driver manufactured therefrom is shown in FIG. 7. The result of taking the surface of the manufactured actuator by SEM is shown in FIG. Referring to Figure 7, it can be seen that the graphene foam is well attached to the nylon fiber. The driving time was measured in the same manner as in Example 1 for the manufactured driver. As a result, it is shown in FIG. Referring to FIG. 8, the total driving time of the actuator after graphene foam coating was significantly shortened, and the total driving time of about 14% was reduced.

Example  5

A large area of single layer graphene was used as a heat dissipating material, and a large area of graphene was wound on a driver to prepare a driver. The driver manufactured therefrom is shown in FIG. 9. The result of taking the surface of the manufactured driver by SEM is shown in FIG. Referring to Figure 9, it can be seen that the graphene is well attached to the nylon fiber. When the driving time was evaluated in the same manner as in Example 1 with respect to the manufactured actuator, the driving time was reduced by about 18% compared to before the coating.

Example  6

The twisted structure prepared in Example 1 was heated at 100 ° C. to shrink the twisted structure. At this time, the shrinkage of Equation 1 was 12%. A solution containing the prepared heat dissipating material was coated on the shrunk twist structure using a spray gun. In this example, the actuator was manufactured in the same manner except that the coating amount was increased to about 4.5 mg and the graphene coating amount was increased three times. SEM photographs of the coated surfaces are shown in FIG. 10. When compared with FIG. 3 when the coating by shrinking the actuator by heating, it can be seen that the heat dissipation material is uniformly coated on the surface of the driver, it can be seen that does not enter well into the pores in the driver fiber strands. The drive time was evaluated by the same method as Example 1 about the manufactured driver. The results are shown in FIG. As in FIG. 11, the driving time was reduced by about 26%. Compared with Example 1, the coating amount was about three times higher than that of Example 1, but in general, when the coating amount is increased, the rigidity of the coating layer is increased, thereby deteriorating driving characteristics. However, although the coating amount was increased, it was confirmed that the driving characteristics were equally obtained even though the coating layer was formed thick. This confirmed that it is very effective to coat the heat radiation material by shrinking the actuator through heating.

Simple modifications and changes of the present invention can be easily made by those skilled in the art, and all such modifications and changes can be seen to be included in the scope of the present invention.

Claims (11)

Comprising at least two polymer unit fibers,
Two or more of the polymer unit fibers have a twist structure or a coil structure,
An actuator, comprising a heat dissipating material on the surface of the torsion structure or the twist structure,
The heat dissipating material is solid, and includes at least one of graphene, graphite, carbon nanotubes, metal nanowires, and metal nanoparticles,
The driver is thermally driven,
And the heat dissipating material forms a heat dissipation layer.
The driver of claim 1, wherein the torsional structure or the twisted structure includes a void therein surrounded by the unit fibers, and the void does not include a heat dissipating material.
The driver of claim 1, wherein the heat dissipation material does not form a twist structure or a twist structure along the length direction of the polymer unit fiber.
delete The driver of claim 1, wherein the heat dissipation layer is formed of a heat dissipation layer composition including the heat dissipation material and a silicone resin.
The driver of claim 5, wherein the silicone resin comprises polydimethylsiloxane.
delete The actuator of claim 1, wherein silver is further coated on the polymer unit fiber surface.
delete Comprising at least two polymer unit fibers and forming a torsional or twisted structure for at least two of the polymer unit fibers,
A method for manufacturing a driver comprising the step of coating a heat radiation material on the torsion structure or twist structure,
The heat dissipating material is solid, and includes at least one of graphene, graphite, carbon nanotubes, metal nanowires, and metal nanoparticles,
The driver is thermally driven,
The heat dissipating material is to form a heat dissipation layer by the coating step, the manufacturing method of the driver.
An artificial muscle comprising a driver according to any one of claims 1 to 3, 5, 6 and 8 or a driver manufactured by the manufacturing method of claim 10.

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