JPH0546255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a simple clean room or clean box that can easily and inexpensively provide an internal environment with relatively high air cleanliness.

[Prior Art] Conventionally, the method of creating an environment with high air purity, especially indoors, as described above, involves introducing clean air into the room through a filter, and then recirculating the indoor air through the filter again. A commonly used method is to perform purification using

However, although this method can achieve a very high degree of cleanliness, it requires a series of large-scale systems such as a blower, electric equipment, and filters to blow and circulate the air, and it is difficult to clean the clean room easily. It was not like it would come true.

[Problem to be solved by the invention] On the other hand, the level of requirements regarding air purification varies depending on the purpose and application of the clean room or clean box itself. There are applications that require not-so-high cleanliness of around 200,000 units, and in such cleanliness environments, the current situation is that simple and inexpensive equipment is required.

In other words, such clean rooms and clean boxes include, for example, storage warehouses and storage boxes for precision equipment that generally dislike adhesion of dust, and
Examples include simple isolation spaces set up for patients infected with infectious bacteria or for people suffering from hay fever.

The present invention aims to provide a simple clean room or clean box that is simple, inexpensive, and meets the requirements of such uses.

[Means for Solving the Problems] A simple clean room or clean box of the present invention that achieves the above-mentioned objects has the following configuration.

In other words, 10 of the total area including the wall area, ceiling area and floor area that make up the room or box.
It is a clean room or clean box whose basic structure is that more than 50% of the parts are constructed using electret materials.

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

FIG. 1 is a schematic perspective view schematically showing one embodiment of a simple clean room according to the present invention.

In the figure, 1 is a simple clean room, 2 is an electret material, 3 is an entrance door, and 4 is a support.

The clean room or box of the present invention is
The electret material 2 accounts for 10% or more of the total area of the interior, including the wall area, ceiling area, and floor area.

In the present invention, the electret material 2 is
It may be used on the entire surface of the room, or it may be used on only a portion of one surface. In order to improve the cleanliness of the room, it is preferable to use electret material in as much area as possible. According to the findings of the present inventors, in order to obtain good air cleanliness, it is effective to construct less than 10% of the total area of the walls, ceiling, and floor with electret materials. It is important that the electret material occupies at least 10% of the total area, preferably from 50 to 100%.

In addition, the surface potential of electret materials is
It is preferable to use at least one voltage of 50V or higher. This is because the higher the surface potential, the farther away from the surface of the electret material the dust and dirt in the air will be removed.
Or, because it has a strong ability to attract bacteria, it is effective for improving indoor cleanliness. Therefore, it can be said that it is preferable that the surface potential of the electret material be as high as possible.

Furthermore, according to the findings of the present inventors,
It is even better to use a voltage of 200V or more, and it is generally particularly preferable to use a voltage of about 500V to obtain a very high level of air cleanliness.

Further, there are electret materials of oriented polarization type and random polarization type, but in order to improve the surface potential, it is preferable to use the oriented polarization type, which improves the surface potential by laminating layers. However, since the same type has a positive potential surface and a negative potential surface, it is more preferable to use the same type so that these two surfaces are used in the same area. The reason for this is that dust in the air has both positive and negative charges.

The materials used for the electret material include polypropylene, polyethylene, polycarbonate, polyester, trifluoride polyethylene, tetrafluoride polyethylene, polyacrylic, etc.
Materials with a resistance of 10 ^{to 14} Ω・cm or more are suitable. Among these, polypropylene and polycarbonate are suitable materials because they have excellent electret stability and are inexpensive. The electret material is preferably a fabric, film, or plastic molded body made of the above-mentioned materials. Preferably, an electret material in these forms made of fibers with a surface potential of 50 V or more as described above is used. Good. When a nonwoven fabric is used as the fabric, it is particularly preferable to use a polypropylene melt-blown nonwoven fabric, a polypropylene spunbond nonwoven fabric, or a nonwoven fabric made of a fibrous material obtained by splitting and slitting a polypropylene electret film. Polypropylene nonwoven fabric can be made into a high potential electret and has breathability, so indoor dust and dust can be effectively filtered by the electret material, making it more effective in improving indoor cleanliness. This is because.

On the other hand, polypropylene electret film, polypropylene electret plastic, and polycarbonate electret plastic are preferable because they have a very high degree of electrification and are highly transparent, allowing the inside of the room to be observed from outside. Furthermore, when using these films, it is possible to virtually completely seal the room, so by adding a desiccant and sealing it, it is possible to create an ideal space for storing equipment that dislikes moisture and dust. It is.

Furthermore, when attempting to create a simple clean room or clean box at a lower cost based on the present invention, for example, if an electret material is bonded to the surface of a non-electret plastic body and the bonded electret material is It is effective to use the surface as the interior side of the room or box, and by using it in this way, the amount of expensive electret material used can be reduced.

In addition, when the electret material is a melt-blown nonwoven fabric such as polypropylene, the cutting strength is generally low, so spunbond nonwoven fabrics, woven or knitted fabrics, or film-like materials with a cutting strength of 2 kg/5 cm width or more are layered together by bonding. It is preferable to use it with reinforcement.

According to various studies conducted by the present inventors, the cleanliness inside the simple clean room or clean box of the present invention is such that it effectively maintains good cleanliness, with approximately 150,000 or less particles of 0.5 μm or more in 1 cubic foot. can be achieved. This aerosol concentration of 150,000 particles is equivalent to about 1/2 of the aerosol concentration contained in normal air.

The cleanliness inside the simple clean room and clean box according to the present invention improves over time, but unlike conventional clean rooms, active ventilation and purification are not performed, so the rate of improvement in cleanliness is generally slow. This is because dust and dust contained in the air near the surface of the electret material is attracted to the surface of the electret material by the electrostatic adsorption effect of the electret material. This is because the system is based on a system that gradually improves the cleanliness, and as the cleanliness improves to a certain extent, it becomes difficult to attract dust and dust.

However, according to the findings of the present inventors, over a long period of time, the cleanliness of the inside can be reduced to 10 or less particles of 0.5 μm or more in 1 cubic foot if ideally managed. It is.

In addition, by providing appropriate uneven parts inside the room and inside the box, considering the internal volume,
By proactively increasing the total area of what can essentially be called walls, ceilings, and floors, and using electret materials at a higher rate for that large total area, we have achieved a high level of air purification. It is also possible to obtain a degree. That is, the interior of the room or box of the present invention is not limited to simply consisting of six planar walls, a ceiling, and a floor, but the total area is substantially increased by appropriate means,
In addition, it may be constructed by increasing the area in which the electret is used.

Furthermore, for example, walls, ceilings, floors, etc. do not necessarily have to be fixed; non-fixed walls, ceilings, or floors such as sliding doors or accordion doors may be used as appropriate. Therefore, it may be possible to substantially configure walls, ceilings, etc. only when necessary. In that case, if the sliding door, accordion wall (such as an accordion curtain), ceiling or floor are made of electret material, a simple clean room or clean room having the desired effect of the present invention can be created. Boxes can now be formed even more easily and immediately when needed.

In the above description, the surface potential was measured using Model 244 manufactured by Monroe, USA.

[Example] Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A clean box (width 30 x 40 x depth 40 cm, thickness 5 mm, volume resistivity 10 ¹⁶ Ω cm), whose entire inner surface was made of polycarbonate electret plastic with a surface potential of 2000 V, was thoroughly cleaned. An optical lens was placed in the container, the lid was placed, and the container was stored for 10 days.

After 10 days, the lens was removed and observed under a microscope to see that there was very little dust.

Next, the cleanliness inside the clean box was measured using a laser particle counter (model LAS manufactured by PMS, USA).
-X-CRT) was used to evaluate the number of particles of 0.5 μm or more, and the number was 1000 or more per cubic foot, indicating an extremely high level of cleanliness.

Comparative Example 1 An optical lens was placed in the same manner as in Example 1 in a non-electret box made of the same material and the same shape as the clean box used in Example 1 above, but made of plastic that was not made into an electret. and stored under the same conditions.

After 10 days, the lens was taken out and observed under a microscope to see how much dust had adhered to it.

Next, we evaluated the cleanliness inside this box using a laser particle counter and found that there were as many as 20,000 particles in 1 cubic foot, indicating an extremely low level of cleanliness. I found out something.

Example 2 In a room where cedar pollen was dispersed at a rate of 100 particles per cubic foot, an electrified polypropylene melt-blown nonwoven fabric (fiber 0.04 denier, basis weight 50 g/m ² ) with a surface potential of 350 V was used on the entire inner surface. Simple clean room (Width 220 x 180 x Depth 230
cm) was assembled.

Eight hours after it was assembled, five patients with hay fever were asked to enter the simple clean room and the pollen allergy status in the clean room was evaluated through interviews. It was confirmed that these symptoms did not develop.

This was believed to be due to the fact that pollen inside and outside the simple clean room was collected by the electretted polypropylene melt-blown nonwoven fabric, reducing the amount of pollen reaching the patient's throat and nose.

Comparative Example 2 Five patients with hay fever were asked to enter a room where cedar pollen was dispersed at a rate of 100 particles per cubic foot, and their pollen allergy status in the room was evaluated through interviews. All five of them developed various symptoms of pollen allergy. This was thought to be the result of cedar pollen reaching the patient's throat and nose.

[Effects of the Invention] By using the simple clean room or clean box of the present invention, a highly clean environment can be easily created at low cost.

Therefore, measures against hay fever and smoking smoke, which are currently becoming a problem, can be easily implemented.

Furthermore, depending on the shape and size of the simple clean room or clean box, it is possible to manufacture a type that can be easily assembled in a general household, so if you use it when you have a cold, for example, You can prevent infection to your family.

It is also superior in terms of energy savings, as it does not require ventilation equipment, motors, or electricity unlike conventional clean rooms.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing, as a model, one embodiment of a simple clean room according to the present invention. 1: Simple clean room, 2: Electret material, 3: Entrance door, 4: Support pillar.

Claims (1)

[Scope of Claims] 1. A room or box in which 10% or more of the total area of the wall area, ceiling area, and floor area is constructed using an electret material with a surface potential of 50 V or more. A clean room or clean box characterized by: 2 A portion of 10% or more of the total area of the room or box, including the wall area, ceiling area, and floor area, is made of electret fiber fabric or electret fabric mainly made of a material with a volume resistivity value of 0 ¹⁴ Ω・cm or more. 1. A clean room or clean box characterized in that it is constructed using an electret material made of an electret film or an electret plastic molded body. 3. If electret material is bonded to the surface of a non-electret plastic body and electret material is bonded to the surface of a non-electret plastic body and A clean room or clean box characterized in that the bonded surfaces are constituted by an electret body used as the interior side of the room or box. 4 10% or more of the total area including wall area, ceiling area and floor area is constructed using electret material, and the electret material is
A clean room or clean box characterized in that it is mainly used for non-fixed wall-like, ceiling-like, or floor-like objects that can substantially form walls, ceilings, or floors when necessary. 5. The clean room or clean box according to claim 1, 2, 3, or 4, wherein the electret material is a nonwoven sheet made of polypropylene fibers. 6. Claim No. 6, characterized in that the electret material is mainly made of polypropylene melt-blown nonwoven fabric, and the nonwoven fabric is further laminated with a cloth or film-like material having a sheet cutting strength of 2 kg/5 cm width or more. Clean room or clean box as described in Section 5.