JPH047242B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for removing high-temperature particles when wiping off fine particulate matter present in a liquid or gas and accumulated on a solid surface. The present invention relates to a dust absorbing wiper that can efficiently adsorb fine particulate matter, and relates to an excellent dust absorbing wiper that has long adsorption performance and is highly durable.

In the present invention, a dust-absorbing wiper is a wiper that, when wiping to remove dust existing on the surface of an object to be wiped, causes the dust to stick to the surface of the wiping material, thereby removing the dust from the surface of the object to be wiped. It refers to a wiping material that can be used to clean things (therefore, it is different from a filter).

[Prior Art] Conventionally, Japanese Patent Publication No. 59-21964 has introduced cleaning tools such as a mop made of electret fibers. This electret fiber has a polarization form in which the charge polarity of the core part and the sheath part of the core-sheath type fiber are different, and these are assembled to form a mop.

However, it is extremely difficult to produce electret fibers having such a polarized structure, and they have not been commercialized. In any case, with such fibers, only the sheath part is involved in adsorption, so there is a drawback that only dust that is charged to the opposite polarity to the sheath part is adsorbed. The adsorption rate is extremely low.

[Problems to be Solved by the Invention] An object of the present invention is to provide an excellent dust absorbing wiper that has high dust adsorption performance over a long period of time. Further, the dust-collecting wiper to be obtained by the present invention includes a material that has good adsorption performance and durability against heat, chemicals, and the like.

Furthermore, the dust-sucking wiper obtained by the present invention is suitable for fields where the ability to adsorb dust, odors, foreign substances, viruses, bacteria, etc. in gas or liquid is required.

[Means for Solving the Problems] The present invention, which achieves the above-mentioned object, has the following configuration. That is, the surface has a charge, and the activation energy of the polarized charge constituting the charge is at least
0.2 eV, has an electric field structure in which polarized charges are oriented in the thickness direction of the sheet, has an amount of polarized charges of 2×10 ^-10 coulombs/cm ² or more, and has an average fiber diameter of the constituent fibers of 10 μm. The basis weight is below 80
This is a dust-collecting wiper characterized by being made of a fiber sheet having a particle size of less than g/m ² .

[Effect] The present invention will be explained in more detail below.

In the present invention, having an electric charge on the sheet surface means
Like normal electret sheets, it means that the surface has positive or negative charges.

In the present invention, the amount of such charge is not particularly limited, but if it is too weak, the performance may be inferior, so the amount of polarized charge held within the fiber sheet should be at least 2×
Having a charge amount of 10 ^-10 coulombs/cm ² or more,
This is necessary to improve dust absorption performance.

It is also important that the fiber sheet has a basis weight of 80 g/m ² or less, and a thickness of 50 g/m ² or less is particularly preferable for the dust-collecting wiper of the present invention. In other words, a material with a large basis weight exceeding 80 g/m ² may be preferable in the field of filters, etc., but in the field of wipers such as the present invention, it is completely undesirable as it lacks softness. It is difficult to increase the amount of electric charge with a material having a large basis weight, and it is difficult to obtain a high electric charge of 2×10 ^-10 coulombs/cm ² or more as in the above-mentioned product of the present invention.

Furthermore, it is important to use a fiber diameter of preferably 10 μm or less, since it is easier to increase the amount of polarization charge when the fiber is thinner than when it is thicker.

Furthermore, the apparent density of the fiber sheet is 0.05g/
cm ² or more, more preferably 0.1 g/cm ² or more, because it can increase the application efficiency and improve the stability of the adsorption performance of the resulting dust-collecting wiper. This is desirable.

For the fiber sheet that can be used in the dust-collecting wiper of the present invention, materials having an electrical resistivity of 10 ¹³ Ω·cm or more can be preferably used, such as polyolefin, polyester, polycarbonate,
A sheet made of a fibrous material made of synthetic resin such as polyfluorine resin, glass, or other inorganic compound is suitable. The term "fibrous sheet" as used in the present invention means a sheet-like material made of a fibrous material, and the fibrous material may be of any form as long as a part thereof has the shape of a fiber. No problem. Furthermore, in the present invention, the fibrous material includes, for example, a fibrous material coated with an organic compound having an electrical resistivity of 10 ¹³ Ω·cm or more, such as a core-sheath type fiber.

The form of such a sheet-like material is not particularly limited, but a fabric-like material is desirable from the viewpoint of flexibility and ease of design for various uses. As such a cloth-like material, for example, a non-woven fabric, a knitted fabric, a paper-like material, etc. are most suitable.
Of course, these fabrics also include those in which at least a portion or one side of these fabrics is made into a film, porous films made of fibrous materials, sponge-like sheets, and the like. Furthermore, such sheet-like materials may be processed with a resin using an organic compound having an electrical resistivity of 10 ¹³ Ω·cm or more.

The dust-collecting wiper of the present invention is composed of an electret fiber sheet, and the electric charge of the electret fiber sheet is characterized in that the polarization charge constituting it has an activation energy of at least 0.2 eV. It is true.

This activation energy can be found from a chart like the one shown in Figure 4, which records the amount of current generated by depolarization of polarized charges depending on temperature, but this energy is , represents the depth of the charge trap in the electret, and has a great influence on the life and durability of the suction performance of the dust suction wiper of the present invention.

The activation energy is measured using a heating tank 6 having a temperature control device 5, as shown in FIG.
Both sides of the electret sheet 2 placed in the electret sheet 2 are tightly sandwiched between electrodes 3 and 4, and the electrodes are connected to a high-sensitivity ammeter 7 for measurement. That is, when the temperature of the heating tank is raised at a constant heating rate, for example, 5° C./min from room temperature to around the melting point, the trapped charges are depolarized and a current flows. When this current is recorded on the recorder 9 via the data processing device 8, current curves for various temperature ranges are obtained (FIG. 4).
The quotient obtained by dividing the area of this current curve by the area of the measurement sample is the amount of polarized charge.

Since the rise of each peak in this chart follows the following formula, it is possible to plot In J versus 1/T for the rise of the peak and calculate the activation energy of the polarized charge from the slope of the obtained straight line. .

In J=C-ΔE/kT [In the formula, J: depolarization current (A), C: constant, ΔE: activation energy (eV), k: Boltzmann constant, T: temperature (°k)] Activation energy From the viewpoint of charge stability, it is important that the current peak above room temperature be at least 0.2 eV. In other words, the larger the activation energy value, the better the suction life of the dust suction wiper of the present invention.

For this reason, in the present invention, the activation energy is further set to 0.5 eV or more, particularly preferably
Those with a value of 0.7 eV or more exhibit even better characteristics in terms of heat resistance and chemical resistance.
In addition, the higher the temperature range in which the peak occurs, the better the adsorption life is, and those that are at least 40°C, preferably 80°C or higher, and particularly preferably 130°C or higher have better durability and stability. It is.

The dust absorption wiper of the present invention has better adsorption performance when the polarization charge amount of the electret fiber sheet is larger, and as mentioned above, it is at least 2×10 ^-10 coulombs/cm ² or more, particularly preferably 5×
It is preferable to use one having a charge amount of 10 ⁻¹⁰ coulombs/cm ² or more.

Other features of the dust suction wiper of the present invention are as shown in FIG.
As shown in FIG. 2, the electret fiber sheet 2 used in the dust-collecting wiper has an electric field structure in which polarized charges 1 are oriented in one direction in the thickness direction of the sheet.

Specifically, the same surface of the sheet 2 has the same type of charge. In the present invention, the sheet further has a polarized structure having different types of charges in the thickness direction, such as a polarized charge structure in which the upper half is made up of only positive electrodes and the lower half is made up of only negative electrodes. There is no problem.

The electric sheet constituting the dust suction wiper of the present invention can constitute a dust suction wiper having excellent suction performance even when used alone (one sheet), but by collecting and stacking a plurality of such sheets, it is possible to further improve the suction performance. You can obtain something that has a long life and is highly durable against external conditions. The laminate may be integrated, and as the integration means, for example, joining means using various resins or mechanical means can be applied. Typical examples of the former include adhesives, and examples of the latter include embossing. In this lamination, the lamination method may be arbitrary, and the layers may be laminated in the same orientation direction of the polarized charges as shown in FIG. 5, or may be laminated in opposite directions. Of course, there is no problem even if these layers are mixed together in a laminated state.

The electret fiber sheet used in the dust-collecting wiper of the present invention can be manufactured using, for example, an apparatus having the structure schematically shown in FIG.

That is, a fiber sheet 10 formed by a normal, appropriate method is placed on a water electrode 11 set at an appropriate temperature (by the way, during electret processing, it is important to increase the contact area between the fiber sheet and the electrode. (As will be explained later, using the water electrode described above is one effective technical means).
A high voltage DC current is applied to the surface of the fiber sheet opposite to the water electrode 11 using a needle electrode 12 .

The applied voltage varies depending on the type of material constituting the fiber sheet 10, its intramolecular structure, the thickness of the sheet, the shape of the needle electrodes, the distance between the electrodes, etc., but for example, when the distance between the electrodes is 3 cm, at least 10kv,
Preferably 15~50kv, more preferably 25~
It is 40kv. The application time may be instantaneous depending on the case, but it is usually 0.1 seconds or more, preferably 1 to 1 second.
You only have 60 seconds to make your selection.

In this case, applying a double-sided treatment method in which a negative high pressure is applied to one side of the fiber sheet 10 and a positive high voltage is further applied to the opposite side has an excellent adsorption performance with a higher polarization charge. This method is preferable because it allows the production of an electret fiber sheet.

In particular, in order to obtain a high-performance electret fiber sheet in which the activation energy of the polarization charge defined in the present invention is at least 0.2 eV or more, further 0.5 eV or more, and even 0.7 eV or more as described above, Although the method is not particularly limited, according to various findings of the present inventors, it is possible to perform electrification processing using a water electrode as described above, and then to make contact between the fiber and the electrode. Under conditions where the contact area is extremely large (regardless of the surface unevenness of the fiber sheet surface caused by overlapping fibers, the water that is the water electrode enters into the gaps between the fibers, so the contact between the fibers and the electrodes is To realize electret processing with good contact and a large contact area), and to realize electret processing with both positive and negative surfaces 2.
It is important to perform step electret processing.

In addition, when using the dust suction wiper of the present invention,
In order to more efficiently adsorb fine particles existing in the air, liquids, and solid surfaces, a turbulent air flow, a suction air flow, or a blowing air flow is applied from an appropriate direction to lift up the fine particles to be adsorbed. It is also possible to use physical means to make it easier to move in the direction of adsorption or adsorption.

[Example] Hereinafter, the structure and effects of the dust suction wiper of the present invention will be specifically explained based on Examples.
The present invention is not limited to these examples in any way.

Example 1 Average fiber diameter 4.0μm, basis weight 20g/m ² , apparent density
A 0.128 g/cm ² polypropylene nonwoven sheet was electretted using the apparatus schematically shown in FIG.

The temperature of the water electrode was 40°C, the distance between the electrode and the needle electrode was 3 cm, the applied voltage was -28 kV, and the treatment time was 30 seconds. Next, this sheet was dried, the sheet was turned over and placed on a water electrode, and the back side of the sheet was further subjected to electrification treatment at +20 KV for 30 seconds. In this way, the current peaks of the obtained electret fiber sheet are 90℃ and 150℃, and the activation energy at each peak is
They were 0.52eV and 0.84eV.

The amount of polarization charge of this sheet is 7.0×10 ^-10 coulombs/cm ² , and the amount of polarization charge at temperatures above 130°C is 4.3×
It was 10 ^-10 coulombs/ ^cm2 .

One of the electret fiber sheets was used to form a dust absorbing wiper, and the dust absorbing performance of the dust absorbing wiper was evaluated by the following method.

That is, three times the amount (weight) of the JIS type 8 test powder as the sample is loaded into a 500 ml container made of polyethylene, and then, after setting the sample, the container is shaken for one minute. The sample was taken out from the container, its weight was measured, and the dust adsorption rate was determined by dividing the determined amount of dust by the weight of the sample before the test.

The durability of the dust absorbing wiper was determined by leaving the adsorbent in an atmosphere of 20° C. and 65% RH for one month, and then measuring the dust adsorption property using the above method and comparing it with the initial value.

As a result, the dust suction wiper according to the present invention had an initial adsorption rate of 65%, and an adsorption rate of 65% after one month, and no deterioration in adsorption performance was observed at all.

Example 2 The electret fiber sheet obtained in Example 1 was
The sheets were laminated so that the charge polarity on the surface of the laminated side of each sheet was different (in the same direction as shown in FIG. 5), and the dust-collecting wiper of the present invention was formed using this laminated sheet. .

This dust absorbing wiper was immersed in methanol at room temperature for one week, and then placed in a dryer at 80°C for 1 week.
After being left for a week, the adsorption performance was evaluated using the same method as used in Example 1.

As a result, this dust wiper has an initial value of 88%
Although a slight decrease was observed in each sample after one week, the adsorption rates were almost the same, confirming that the dust-collecting wiper of the present invention has excellent durability. did it.

[Effects of the Invention] According to the present invention as described above, there is provided a dust-collecting wiper that has stable and high adsorption performance over a long period of time, has strong performance maintenance performance against chemicals and heat, and has excellent durability. is provided.

The dust suction wiper of the present invention can be suitably used, for example, in various wiper applications that require strong and highly efficient suction performance.

For example, it can be used as a wiper for pianos, furniture, show cases, automobiles, etc., or as a wiper for electrophotography and electrostatic printers. In particular, the dust-absorbing wiper of the present invention is extremely effective in wiping off polarized toner, and the toner can be removed very effectively with just a light wipe, and it also prevents damage to the object to be wiped. This can be prevented and is very useful in actual use.

Further, since the wiping material itself is made of a flexible fiber sheet, it can be easily molded into desired shapes as dust-absorbing wipers in various forms such as sheets and rods.

Further, the dust suction wiper of the present invention is very suitable for adsorbing fine particles, dust, aerosols, bacteria, viruses, etc. in liquids and gases.

[Brief explanation of drawings]

FIG. 1 is a schematic model diagram showing the state of polarization and charge in the cross section of an electret fiber sheet used in the dust-collecting wiper of the present invention. FIG. 2 is a schematic model diagram showing power vector lines (arrows) of the fiber sheet shown in FIG. FIG. 3 is a schematic diagram showing an apparatus for measuring polarization charge amount and activation energy. FIG. 4 is a diagram schematically showing an example of the depolarization current curve of the electret fiber sheet used in the adsorbent of the present invention. FIG. 5 is a schematic model diagram showing the state of vector lines of a structure in which three layers of electret fiber sheets are laminated to be used in the adsorbent of the present invention. FIG. 6 is a cross-sectional model diagram showing an example of an apparatus for producing an electret fiber sheet used in the adsorbent of the present invention. 1: polarized charge, 2: electret sheet,
3, 4: Electrode, 5: Temperature control device, 6:
heating tank, 7: high-sensitivity ammeter, 8: data processing device, 9: recorder, 10: fiber sheet, 11:
Water electrode, 12: needle electrode.

Claims (1)

[Claims] 1. Has a charge on its surface, has an activation energy of polarized charges constituting the charge of at least 0.2 eV, and has an electric field structure in which the polarized charges are oriented in the thickness direction of the sheet. and the amount of polarized charge is 2
×10 ^-10 coulombs/cm ² or more, the constituent fibers have an average fiber diameter of 10 μm or less, and a basis weight of 80 g/m ² or less. 2. The dust-collecting wiper according to claim 1, characterized in that a plurality of fiber sheets are laminated.