JP7326858B2 - Triboelectric charging unit, and triboelectric power generation device and dust collection device provided with the triboelectric charging unit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a triboelectric charging unit capable of charging electric charges generated by friction.

2. Description of the Related Art Conventionally, a member is electrically charged by friction to collect fine dust in the air or to remove dirt from the member. For example, Patent Literature 1 discloses a dust collecting device that collects dust electrostatically using a dust collecting plate charged by friction.

Patent Document 1 exemplifies combinations of acrylic and nylon, and polyester and nylon, as dust collection plates and friction plates used in a dust collection device. ing. For this reason, PTFE (polytetrafluoroethylene) resin is mostly used as a negative charging material for dust collecting members that are electrically charged by friction because negative charging is most likely to occur in the charging order. From the viewpoint of the likelihood of negative charging, polytetrafluoroethylene resin is followed by silicone resin, vinyl resin, and polyethylene resin in this order (see Non-Patent Document 1).

Therefore, it is understood that the use of PTFE resin as the negative charging member is preferable because the charge amount can be maximized regardless of the combination with any positive charging material for triboelectrification. On the other hand, nylon is typically used as the positive charging member.

Japanese Patent Application Laid-Open No. 2002-336733

Static Electricity Doctor "Electric Line", [online], Keyence Corporation, [Searched on April 22, 2019], Internet <URL: https://www.keyence.co.jp/ss/products/static/static-electricity /basic/nature.jsp

However, although fluorine-containing resins such as PTFE are excellent in triboelectrification properties, they cannot be said to have sufficient durability. An object of the present invention is to provide a triboelectrification unit that can achieve both triboelectrification property and durability.

The inventors of the present invention have investigated a material that has the same level of triboelectrification properties as when PTFE is used as a negatively charged member and at the same time has durability greater than that of PTFE. The inventors have found that the above problems can be solved by using a polyester resin as a negative charging member, which is considered to have a smaller distance from the positive charging member than PTFE and is significantly inferior in triboelectrification properties. reached.

The present invention includes the following.
[1] A triboelectric charging unit having a positive charging member and a negative charging member disposed so as to be in contact with the positive charging member, and capable of being charged by friction between the positive charging member and the negative charging member. hand,
A triboelectrification unit, wherein the negatively charged member is a stretch molded body of polyester resin.
[2] The triboelectric charging unit according to [1], wherein the polyester resin is selected from polyethylene terephthalate resin and polyethylene naphthalate resin.
[3] A triboelectric charging unit having a positive charging member and a negative charging member disposed so as to be in contact with the positive charging member, and capable of being charged by friction between the positive charging member and the negative charging member. hand,
A triboelectric charging unit, wherein the negative charging member is polyester resin and is selected from polyethylene terephthalate resin and polyethylene naphthalate resin.
[4] The triboelectric charging unit according to any one of [1] to [3], wherein the polyester resin has a stretching degree of 2.5 times or more and 7 times or less in at least one direction.
[5] The frictional charging unit according to any one of [1] to [4], wherein the negative charging member has a thickness of 10 μm or more and 2 mm or less.
[6] A dust collection device comprising the triboelectrification unit according to any one of [1] to [5].
[7] A power generation device comprising the triboelectrification unit according to any one of [1] to [5].

According to the present invention, it is possible to provide a negative charging member that can achieve both triboelectrification property and durability. Further, it is possible to provide a triboelectric charging unit having the negative charging member and the positive charging member. Further, it is possible to provide a dust collection device and a power generation device using the triboelectrification unit.

1 is a schematic diagram showing an embodiment of a power generation device provided with a triboelectrification unit; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the outline|summary of the experimental apparatus used in the Example.

Hereinafter, the present invention will be described in detail, but the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is not limited to these contents. Various modifications can be made within the scope of the gist.

One embodiment of the present invention has a positive charging member and a negative charging member disposed in contact with the positive charging member and can be charged by friction between the positive charging member and the negative charging member. It is a triboelectrification unit. A polyester resin is used as the negative charging member.
The positive charging member and the negative charging member slide against each other and/or repeatedly contact and separate from each other to generate charges and charge. In this embodiment, a polyester resin is used for the negative charging member that charges negative charges generated by friction. It should be noted that the generation of electric charge by the sliding and the contact/separation is referred to as "friction".

The positively charging member is not particularly limited as long as it can negatively charge the polyester resin used as the negatively charging member, and can itself be negatively charged in combination with the polyester resin, such as PTFE resin, silicone resin, and vinyl resin. Avoid materials that are highly resistant. Nylon is typically used, but is not limited to this.

The present invention will be described below with reference to specific embodiments shown in the drawings. FIG. 1 shows a form in which the triboelectric charging unit of this embodiment is applied to a triboelectric power generation device.
In the triboelectric power generation device 10, a positive charging member 3 is supported by a base material 1 for positive charging members, and a negative charging member 4 is supported by a base material 2 for negative charging members. The positive charging member 3 and the negative charging member 4 are not fixed. By repeating contact and separation with the member 4, a positive charge is generated on the positive charging member 3 and a negative charge is generated on the negative charging member 4, respectively. Friction between the positive charging member 3 and the negative charging member 4 can be achieved by moving the positive charging member 3 and the negative charging member 4 using a known driving method.

The substrates 1 and 2 supporting the charging member are conductive members, and electricity generated from the wiring 5 electrically connected to the substrates 1 and 2 can be taken out. When the triboelectrification unit is used as a dust collecting device, one end of the wiring electrically connected to the substrate may be grounded.
Although the base material 1 and the base material 2 are not necessarily required, it is preferable to have them in terms of handleability and the like. Also, the material is not particularly limited as long as it has sufficient strength to support the charging member. Also, an adhesive layer may be provided between the substrate and the charging member. The adhesive layer in this case can be provided for the purpose of improving adhesion to the substrate.

The negative charging member 4 is made of polyester resin, and if at least the outermost layer in contact with the positive charging member 3 is made of polyester resin, it may be a laminate with other members. The polyester resin is not particularly limited, but polyethylene terephthalate resin and polyethylene naphthalate resin are preferable because the surface is less likely to be damaged by repeated use. Moreover, it is preferable that it is a stretch molded article.
The positive charging member 3 is not particularly limited as long as it can negatively charge the polyester resin used as the negative charging member 4, and is typically nylon. The positive charging member 3 may be sheet-shaped, or may be brush-shaped in order to increase the amount of static electricity generated.

Next, an example of manufacturing a polyester film, which is a negative charging member, will be described.
Although the shape of the polyester used as the negative charging member in this embodiment is not particularly limited, it is generally used in the form of a film having a thickness of 2 mm or less, but is not particularly limited, and may have a thickness of 500 μm or less. The lower limit is also not limited, and is usually 5 μm or more, and may be 10 μm or more.

As a method for producing the polyester film, a generally known production method can be employed, and there is no particular limitation.
For example, when producing a biaxially oriented polyester film, a polyester raw material is melt-extruded through a die with an extruder, and the melted sheet is cooled and solidified with a cooling roll to obtain an unstretched sheet. In this case, it is preferable to increase the adhesion between the sheet and the cooling roll in order to improve the flatness of the sheet, and an electrostatic application adhesion method or a liquid application adhesion method is preferably employed.

Next, the obtained unstretched sheet is unidirectionally stretched by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120° C., preferably 80 to 110° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times.
Next, the film is drawn in a direction perpendicular to the drawing direction of the first stage at a temperature of usually 70 to 170° C. at a draw ratio of usually 2.5 to 7 times, preferably 3.0 to 6 times. Subsequently, heat treatment is performed at a temperature of 180 to 270° C. under tension or under relaxation of 30% or less to obtain a biaxially oriented film.
In the above stretching, a method of stretching in one direction in two or more stages can also be employed. In that case, it is preferable that the stretching ratios in the two directions finally fall within the above ranges.

A simultaneous biaxial stretching method can also be employed as a method for producing a polyester film.
The simultaneous biaxial stretching method is a method of simultaneously stretching and orienting the unstretched sheet in the length direction and the width direction while the temperature is controlled at usually 70 to 120°C, preferably 80 to 110°C. The draw ratio is usually 4 to 50 times, preferably 7 to 35 times, more preferably 10 to 25 times in terms of area ratio. Subsequently, heat treatment is performed at a temperature of 170 to 270° C. under tension or under relaxation of 30% or less to obtain a stretched and oriented film. Conventionally known stretching methods such as a screw method, a pantograph method, a linear drive method, and the like can be used for the simultaneous biaxial stretching apparatus that employs the above-described stretching method.
Whether or not it is a stretched molded product can be confirmed by a known method. As described in "Analysis of higher-order structure change accompanying stretching of crystalline polymer film", the downward peak due to the glass transition of the amorphous part in the storage modulus-temperature curve is changed to unstretched by stretching. The temperature difference between the glass transition and cold crystallization by DSC is reduced by stretching compared to the unstretched, the change in diffraction pattern by X-ray diffraction, Raman spectroscopy It should be analyzed in a way that is easy to apply according to the situation.

The polyester film may be a multi-layer polyester film composed of a plurality of layers, or may be a film having a coating on its surface, as long as the chargeability is not greatly impaired. The surface coating may be provided by in-line coating, in which the film surface is coated during the production process of the polyester film, or offline coating, in which the film once produced is coated outside the system. It is preferably formed by in-line coating.

In-line coating is a method of coating in the process of polyester film production, specifically, a method of coating at any stage from melt extrusion of polyester to stretching, heat setting and winding. Usually, it is coated on an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or a film after heat setting and before winding.
Although not limited to the following, for example, in sequential biaxial stretching, a method of coating a uniaxially stretched film stretched in the longitudinal direction (machine direction) and then stretching in the transverse direction is excellent. According to such a method, film formation and coating layer formation can be performed at the same time, which is advantageous in terms of manufacturing cost. In addition, since stretching is performed after coating, the thickness of the coating layer can be changed by the stretching ratio. , thin film coating can be performed more easily than offline coating.

Further, by providing the coating layer on the film before stretching, the coating layer can be stretched together with the base film, thereby firmly adhering the coating layer to the base film. Furthermore, in the production of biaxially stretched polyester film, the film can be restrained in the vertical and horizontal directions by holding the ends of the film with a clip or the like while the film is stretched. High temperature can be applied while maintaining the properties. Therefore, since the heat treatment applied after coating can be performed at a high temperature that cannot be achieved by other methods, the film-forming property of the coating layer is improved, and the coating layer and the base film can be adhered more firmly. Furthermore, a strong coating layer can be formed, and performances such as adhesion with various functional layers that can be formed on the coating layer and resistance to moist heat can be improved.

The triboelectrification unit, which is one embodiment of the present invention, can be used for applications such as a power generation source for a triboelectric power generation device, a sensor, and a dust collection sheet for a dust collection device. It is explained below.

A triboelectric power generator utilizing charging by friction has a structure in which a pair of electrode members having an electrode and a charging member face each other. When the surfaces of the opposing charging members repeatedly contact and separate, the surface layers are charged to opposite polarities. When the charging members are in contact with each other, the electric fields created by the positive and negative charges cancel each other out, so that the potential difference between the electrodes is equal. When the charging members are separated from each other, a potential difference is generated between both electrodes. When both electrodes are electrically connected via a load resistor, charge flows through this connection. Charge flows until the potential difference between the electrodes becomes zero, and this flow is current.

Even when it is used as a power source for a sensor, it has a structure in which a pair of electrode members having an electrode and a charging member face each other, similar to the power source for a friction generator. It can be used as a sensor by detecting, as a signal, electric charges that flow when the surface of the charging member of the electrode member repeatedly contacts and separates.

When used for dust collection using frictional electrification, it has at least a charging member and a friction member for electrifying it. Friction between the surface of the charging member and the friction member causes the sliding surface of the charging member to become charged, and the charged surface can be used to collect charged particles in the air.
The above-described device using the frictional charging unit of the present embodiment is more durable than the device using the conventional negative charging member using PTFE, so the frequency of replacement of the charging member can be reduced. It is possible and preferable.

EXAMPLES Hereinafter, the present invention will be described in more detail by showing examples, but the present invention is not limited by the specific description of the examples.
<Example 1>
As a negative charging member, aluminum was vapor-deposited to a thickness of 100 nm on one side of a PET film having a thickness of 100 μm by an electron beam vapor deposition method. A PET film on which aluminum was vapor-deposited was attached to an aluminum cylinder of 80 mmφ so that the surface on which aluminum was vapor-deposited was in contact with the cylinder. The adhered PET film was carefully wiped with a cloth moistened with pure water, air-dried, and confirmed by a surface potential meter that it was not charged.

Next, an experimental apparatus shown in FIG. 2 was prepared. In the experimental device, a semi-cylindrical supporting member 21 with a radius of 5 mm was wrapped with a nylon cloth 23 as a positively charged material and pressed against an aluminum cylinder 22 with a PET film 24 attached. The aluminum cylinder 22 was rotated at 12 revolutions per minute, and the nylon cloth 23 and the PET film 24 were rubbed. The peak value of the surface potential of the PET film 24 after 30 rotations was read using a 244-type surface potential meter (25 in the figure) manufactured by Monroe Electronics Co., Ltd., and found to be -613V. From the read surface potential value, the charge density σ of the PET film was calculated using the following formula (1). Table 1 shows the calculated values.
σ=2×V× _ε0 × _εr /d (1)
Here, V is the surface potential, _ε0 is the permittivity in vacuum, _εr is the relative permittivity, and d is the thickness of the film.

<Comparative Example 1>
Measurement was carried out in the same manner as in Example 1, except that a 100 μm thick PTFE film having 100 nm of aluminum vapor-deposited on one side was used as the negatively charged material instead of the PET film. The peak value of the surface potential was -397V. Table 1 shows the charge density σ of the PTFE film calculated in the same manner as in Example 1.

As is clear from Table 1, the PET film achieves a higher charge density at the same film thickness and under the same sliding conditions than the PTFE film used in conventional products, which is said to have a more negative charge level. I know it's done.
In terms of film strength, PET is more resistant to scratches and abrasion than PTFE, so if polyester resin is used as a negatively charged material, for example, for dust collection, it can be used to collect more dust. can be expected to collect and have a longer life.

10 power generation devices 1 and 2 base material 3 positive charging member 4 negative charging member 5 wiring 21 support member 22 aluminum cylinder 23 nylon cloth 24 PET film 25 surface potential meter

Claims (7)

A triboelectric charging unit having a positive charging member and a negative charging member disposed so as to be in contact with the positive charging member, and capable of being charged by friction between the positive charging member and the negative charging member,
A triboelectrification unit, wherein the negatively charged member is a stretch molded body of polyester resin. 2. The triboelectric charging unit according to claim 1, wherein said polyester resin is selected from polyethylene terephthalate resin and polyethylene naphthalate resin. A triboelectric charging unit having a positive charging member and a negative charging member disposed so as to be in contact with the positive charging member, and capable of being charged by friction between the positive charging member and the negative charging member,
A triboelectric charging unit, wherein the negative charging member is polyester resin and is selected from polyethylene terephthalate resin and polyethylene naphthalate resin. The triboelectric charging unit according to any one of claims 1 to 3, wherein the polyester resin has a stretching degree of 2.5 times or more and 7 times or less in at least one direction. 5. The frictional charging unit according to claim 1, wherein the negative charging member has a thickness of 10 μm or more and 2 mm or less. A dust collection device comprising the triboelectrification unit according to any one of claims 1 to 5. A power generation device comprising the triboelectrification unit according to any one of claims 1 to 5.

Images