JP7351507B2 - actuator - Google Patents

Description

The present invention relates to an actuator.

Currently, there is a need to develop lightweight and flexible actuator elements. In particular, the development and research of electrically driven telescoping actuators using various electroactive polymers is expected to be close to practical application.

As such an actuator, research is being conducted on using carbon nanotubes (hereinafter also referred to as CNTs) as actuator electrodes. CNT is a substance made of carbon and has many excellent properties such as high electrical conductivity, light weight, high hardness, and flexibility. Due to its properties, various applications are expected (Non-Patent Document 1).

Kinshi Azaka, Synthesiology, Volume 9, pp. 117-123, 2016

However, CNTs usually exist in the form of nanoscale powder. As a result, it is generally difficult to handle alone, and there are problems in processing. Another problem is that it is difficult to form a complex three-dimensional structure and the degree of structural freedom is low. Thus, when using CNTs as actuator electrodes, further improvement is a challenge.

In view of these problems, it is an object of the present invention to provide an actuator that is easy to process and has a high degree of structural freedom.

The present inventors focused on pulp as a material that is easy to process and is readily available, and developed a CNT composite material that combines CNTs with pulp. In this way, by using a CNT composite material instead of using CNT alone, it becomes possible to further facilitate processing while taking advantage of the excellent characteristics of CNT. They also discovered that if an actuator made of the CNT composite material could be realized, it would be possible to form a complex three-dimensional structure and realize more complex movements than ever before.

One aspect of the present invention, which was completed based on the above knowledge, includes a laminate in which a carbon nanotube composite base material made of a composite of carbon nanotubes and pulp is bonded to at least one surface of a holding base material, and This is an actuator containing an ionic liquid.

In one embodiment of the actuator according to the present invention, the carbon nanotube composite base material contains 5 to 30% by mass of the carbon nanotubes.

In another embodiment of the actuator according to the present invention, the holding base material is a paper base material.

In yet another embodiment of the actuator according to the present invention, the carbon nanotubes are single-walled carbon nanotubes.

In yet another embodiment of the actuator according to the present invention, the pulp is wood pulp, non-wood pulp, or waste paper pulp.

According to the present invention, it is possible to provide an actuator that is easy to process and has a high degree of structural freedom.

1 is a schematic diagram showing the configuration and operating principle of an actuator according to an embodiment of the present invention. FIG. 1 is a schematic diagram illustrating the steps of a papermaking method according to an embodiment of the present invention. It is a schematic diagram explaining the process of the silicone case method concerning an embodiment of the present invention.

Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. It is understood that the present invention is not limited to the following embodiments, and that design changes, improvements, etc. may be made as appropriate based on the common knowledge of those skilled in the art without departing from the spirit of the present invention. Should.

(Actuator configuration)
FIG. 1 is a schematic diagram showing the configuration and operating principle of an actuator according to an embodiment of the present invention. An actuator according to an embodiment of the present invention includes a holding base material and a laminate in which a carbon nanotube composite base material made of a composite of carbon nanotubes and pulp is bonded to at least one surface of the holding base material. It is preferable to bond the carbon nanotube composite base material to both sides of the holding base material because the function as an actuator is further improved.

The shape of the holding base material according to the embodiment of the present invention can be designed as appropriate depending on the use of the actuator, but from the viewpoint of ease of handling and wide range of uses, it is preferably formed into a film shape. . The thickness of the holding base material is not particularly limited, but it can be formed to a thickness of 0.2 to 0.5 mm.

The material for the holding base material according to the embodiment of the present invention is a flexible material that can bond and hold a carbon nanotube composite base material, which is a composite of carbon nanotubes and pulp, on at least one surface. If so, there are no particular limitations. The holding base material preferably has good flexibility, and is more preferably formed from a paper base material, nonwoven fabric, resin sponge, or the like. Further, from the viewpoint of easy application development, the holding base material is preferably formed from the same material as the pulp of the carbon nanotube composite base material to be bonded. For example, if the pulp of the carbon nanotube composite substrate is wood pulp, the holding substrate is preferably a paper substrate. Further, if the holding base material is a paper base material and the pulp of the carbon nanotube composite base material is formed from wood pulp, it is environmentally friendly and can be disposed of by incineration.

The carbon nanotube composite base material according to the embodiment of the present invention is composed of a composite of carbon nanotubes and pulp. The carbon nanotubes of the carbon nanotube composite base material are carbon-based materials made of graphene sheets wound into a cylindrical shape, and are classified into single-walled carbon nanotubes and multi-walled carbon nanotubes depending on the number of peripheral walls. When single-walled carbon nanotubes are used, the flexibility of the carbon nanotube composite substrate is further increased. On the other hand, the use of multi-walled carbon nanotubes further increases the strength of the carbon nanotube composite base material. Single-walled carbon nanotubes and multi-walled carbon nanotubes can be appropriately selected depending on the use of the actuator. Further, the carbon nanotubes of the carbon nanotube composite base material may have a structure such as a chiral (helix) type, a zigzag type, or an armchair type, depending on the structure of the graphene sheet.

The carbon nanotube composite base material according to the embodiment of the present invention preferably contains 5 to 30% by mass of carbon nanotubes. When the carbon nanotube composite base material contains 5% by mass or more of carbon nanotubes, better conductivity can be obtained as an electrode of an actuator. Furthermore, even if the carbon nanotube composite base material contains more than 30% by mass of carbon nanotubes, it becomes difficult to further improve the conductivity as an electrode for an actuator, and this tends to be disadvantageous in terms of cost. There is. In the carbon nanotube composite base material according to the embodiment of the present invention, it is more preferable that carbon nanotubes are contained in an amount of 10 to 30% by mass, and even more preferably 10 to 20% by mass.

The pulp of the carbon nanotube composite base material is not particularly limited, but includes wood pulp (softwood pulp and hardwood pulp), non-wood pulp (kenaf pulp, cotton pulp, bamboo pulp, bagasse pulp, abaca pulp, seaweed pulp, straw pulp, bark pulp, and mulberry pulp). , reed pulp, fruit pulp, etc.) or waste paper pulp can be used.

Further, the pulp of the carbon nanotube composite base material is not particularly limited, but mechanical pulp (MP), chemical pulp (CP), etc. can also be used.

Mechanical pulp refers to pulp made by physically crushing wood into pulp. Types of mechanical pulp include ground pulp (GP), refiner ground pulp (RGP), thermo-mechanical pulp (TMP), and chemi-thermomechanical pulp (CTMP). mo- Mechanical Pulp).

Chemical pulp refers to pulp made by decomposing wood (which must be crushed into chips) and separating lignin through a chemical reaction (called cooking). Types of chemical pulp include kraft pulp (KP), sulfide pulp (SP), and alkaline pulp (AP).

In the actuator according to the embodiment of the present invention, the laminate of the holding base material and the carbon nanotube composite base material contains an ionic liquid. The ionic liquid is generally referred to as a room temperature molten salt or simply a molten salt, and is a salt that exhibits a molten state in a wide temperature range including room temperature (room temperature). The ionic liquid may be one in which a size difference (ion volume difference) is recognized between cations and anions, and it is theoretically possible to produce several thousand or more types.
Although the ionic liquid for the actuator according to the embodiment of the present invention is not particularly limited, it is preferably one that is stable and exhibits a liquid state at normal temperature (room temperature) or a temperature close to normal temperature. As the ionic liquid for the actuator according to the embodiment of the present invention, for example, an ionic liquid containing cations and anions listed in Table 1 below can be used.

(Operating principle of actuator)
As shown in FIG. 1, the actuator according to the embodiment of the present invention has a structure in which a carbon nanotube composite base material is used for the electrode layer, and a holding base material is sandwiched therebetween as an electrolyte layer. This actuator contains an ionic liquid. Ionic liquids contain cations and anions with different ionic volumes. From this state (Fig. 1(a)), ion movement occurs by applying a voltage, and since cations (cations) are larger than anions (anions) in the ionic liquid, cations gather at the negative electrode. The sides expand, and the positive electrode side, where anions gather, contracts (Fig. 1(b)).

According to such a configuration, by using a composite material of CNT and pulp instead of CNT alone in the electrode layer, a network of CNT is formed in the pulp, thereby taking advantage of the excellent properties of CNT, Furthermore, it becomes possible to facilitate processing. Moreover, this makes it possible to form an actuator with a complicated three-dimensional structure, and realize more complicated movements than conventional ones. Furthermore, the presence of pulp fibers in between forms a three-dimensional CNT network with large spacing. Obtaining this gap is important when drawing in cations or anions of the ionic liquid, and it also becomes possible to use larger sized ions. The fact that such large ions can be used has the advantage that larger displacement can be expected. Furthermore, the number of contact areas between CNTs increases three-dimensionally, which improves the durability of the electrode portion (carbon nanotube composite base material) and lowers the resistance.

Examples of the complicated three-dimensional structure that the actuator according to the embodiment of the present invention can have include a paper spring structure, a Miura fold structure, and the like. The paper spring structure is a structure in which two paper base materials are alternately folded, and even if the force of each actuator is small, the force can be amplified by combining them. The Miura fold structure is a structure in which the paper base material can be expanded by holding two points at the edges and pulling it, and can be used, for example, when deploying solar panels on artificial satellites.

Further, when a paper actuator is constructed using a flexible base material such as a paper base material as the holding base material, an actuator that is extremely flexible and has higher durability than conventional ones can be obtained. Furthermore, by combining it with existing origami techniques such as paper springs, it becomes possible to develop actuators with complex shapes and to process them on the spot using scissors or the like to suit the application.

(Actuator manufacturing method and operation confirmation method)
Next, a method for manufacturing an actuator and a method for checking its operation according to an embodiment of the present invention will be described. First, a mixed liquid of a CNT dispersion liquid in which CNTs are dispersed in water and a pulp dispersion liquid in which pulp is dispersed in water is prepared by ultrasonic dispersion or the like.
Next, a carbon nanotube composite base material is produced by a paper-making method in which water is removed using a net, or a silicone case method in which the material is placed in a silicone case and dried. FIG. 2 shows a schematic diagram illustrating the steps of the papermaking method. FIG. 3 shows a schematic diagram illustrating the steps of the silicone case method.

Subsequently, after dehydrating the carbon nanotube composite base material, it is molded and dried using a hot press. Two sheets of carbon nanotube composite base materials are produced in this way, and a holding base material that will become an electrolyte layer is sandwiched between the two sheets of carbon nanotube composite base materials, and they are bonded by hot pressing to produce an actuator.

Next, an ionic liquid is dropped onto the manufactured actuator to impregnate it with the ionic liquid. At this time, the ionic liquid is impregnated into the laminate of the holding base material and the carbon nanotube composite base material constituting the actuator until it no longer absorbs the ionic liquid.
Next, electrodes and conductive wires are provided on the actuator impregnated with the ionic liquid, a predetermined voltage is applied, and the operation of the actuator is confirmed.

The actuator according to the embodiment of the present invention can be used for, for example, furniture, interior decoration, wearable products (tactile stimulation, etc.), logistics, etc., but is not particularly limited. Specifically, protrusions can be made to appear on the surfaces of furniture and interior items as needed. It can also be used as a means to assist in opening and closing doors, drawers, etc. In addition, it is possible to change the shape of various objects. For example, a paper lantern can automatically expand and contract. Regarding logistics, it can be used, for example, as a means to assist in opening and closing the lids of cardboard boxes.

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto.

A mixture of a CNT dispersion in which 15 mg of SGCNT (manufactured by Nippon Zeon Co., Ltd., single-walled CNT) was dispersed in water by ultrasonic dispersion, and a pulp dispersion in which 50 mg of pulp, which is a raw material for paper, was dispersed in water was prepared. CNT composite paper was produced using a paper-making method in which water is removed using a net.

Subsequently, the CNT composite paper was dehydrated, then molded and dried using a hot press. Two sheets of CNT composite paper were produced in this way.

Separately, as a paper base material serving as an electrolyte layer, two layers of K-Dry (manufactured by Nippon Paper Crecia Co., Ltd., 2.82 mg/cm ² ) were used.

Next, the paper base material that will become the electrolyte layer is sandwiched between the two prepared CNT composite papers, and the CNT composite paper is bonded to both sides of the paper base material by heat pressing. An actuator was created. The size of the produced actuator was about length x width x thickness = 1.5 cm x 6.0 cm x 0.03 cm.

The produced actuator was impregnated with the ionic liquid (EMI-TFSI) by dropping 20 μL of the ionic liquid on both sides of each side. Here, the composition of EMI-TFSI is shown in Table 2.

Next, electrodes and conductive wires were provided on the actuator impregnated with the ionic liquid, and when a predetermined voltage was applied, the desired operation of the actuator was confirmed.

Claims (4)

A laminate in which a carbon nanotube composite base material made of a composite of carbon nanotubes and pulp is laminated on both sides of the holding base material,
The laminate contains an ionic liquid,
An actuator in which the holding base material is a paper base material . The actuator according to claim 1, wherein the carbon nanotube composite base material contains 5 to 30% by mass of the carbon nanotubes. The actuator according to claim 1 or 2, wherein the carbon nanotube is a single-walled carbon nanotube. The actuator according to any one of claims 1 to 3 , wherein the pulp is wood pulp, non-wood pulp, or waste paper pulp.