JPH01191408A - Manufacture of functional electret material - Google Patents

Abstract

PURPOSE:To simply manufacture of electret material which has functions of powder and liquid droplets by adhering powder or droplets or the like having specific chemical or physical functions on the surface on the basis of electrostatic attraction of an electret. CONSTITUTION:A specific substance 4 having chemical or physical function is supplied by a supplying unit 5 in a predetermined quantity to an air suction port 11, dispersed in a predetermined concentration by the diffusing power of air 6 introduced from the port, and passed through an electret body 1 by the suction force of a suction fan 8. In this step, the substance is attracted by the electrostatic force of the electret body having 5X10<-11>coulomb/cm<2> or more of surface charge density and collected on its surface. As a result, the attracted substance is formed as a functional electret material 13 having a stable function not easily removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a special electret material,
More specifically, in addition to its performance as an electret, it can effectively impart specific desired chemical or physical functions such as antibacterial and antifungal properties, deodorizing properties, deodorizing properties, and aromatic properties. The present invention relates to a method for producing an electret material having high functionality.

[Prior Art] In recent years, attempts have been made to use electret materials in the field of filters and dust-proofing products, but such filters inevitably become dirty as they are used. There were sanitary issues. Therefore, in addition to having the function of an electret material, there has been a demand for the ability to provide specific functions such as antibacterial and antifungal properties.

Here, a general method for imparting a specific functional function to an object is to mix and disperse a substance having the functional function in a binder or dissolve it in a solvent and attach it together with the binder or solvent. However, the method using a solvent requires the removal of the solvent afterwards, and when this method is applied to an electret sheet, the electret property generally decreases in the solvent removal step, making it unsuitable.

In addition, in the method of dispersing a substance with a specific action function in a binder, the part where the substance is buried in the binder is also created, so in order to expect the action by being on the surface of the object, it is necessary. It was necessary to add the above amount, resulting in poor efficiency.

Another possible method is to disperse and add a functional substance to the raw material of the electret object, but in such a method, for example, when synthetic fiber is used as the electret object, it is difficult to withstand the heat of melting the polymer. The functional material is required to have sufficient heat resistance and heat resistance stability, and the range of selection of functional materials becomes narrower.
This method had limited functionality and could not be called a general-purpose method.

Furthermore, Japanese Patent Application Laid-Open No. 62-42715 proposes a method in which a separate nonwoven fabric that has been treated with antibacterial treatment using a pad method or a spray method is superimposed on one side of an electret nonwoven fabric. This method of using multiple nonwoven fabrics requires a complicated manufacturing process, does not provide a fundamental solution, and has the disadvantage that the overall pressure loss as a nonwoven fabric filter inevitably increases. Ta.

In addition, JP-A No. 62-42716 discloses that after manufacturing a nonwoven fabric using a fiber mass that has been subjected to antibacterial treatment by dipping or spraying at the raw fiber stage, the nonwoven fabric is converted into an electret. However, such a method requires a complicated manufacturing process, and also has problems such as the above-mentioned solvent removal and embedding of specific substances, and it is not always possible to effectively obtain the desired specific function. It wasn't.

[Problems to be Solved by the Invention] In view of the above-mentioned points, an object of the present invention is to effectively maintain the electret properties of an electret material while also effectively achieving desired specific functionality. The purpose of this invention is to provide a method for producing electret materials.

[Means for Solving the Problems] The method for manufacturing a functional electret material of the present invention that achieves the above-mentioned object has the following configuration.

That is, a gas containing a substance having a chemical action function or a physical action function is introduced into or near an electret body having a surface charge density of 5 x 10" coulombs/- or more, and the gas containing a substance having a chemical action function or a physical action function is activated. This is a method for producing a functional electret material, characterized in that a substance having a functional function is adhered to the electret body by the electroadsorption effect of the electret body.

[Function] Hereinafter, the method for manufacturing the functional electret material of the present invention will be explained in detail based on the drawings and the like.

FIG. 1 is a schematic model diagram illustrating one embodiment of the method for producing a functional electret material of the present invention, in which a substance having a specific chemical action or physical action function is produced according to the method of the present invention. This figure shows a state in which air containing (a specific substance) is sucked into an electret body to adhere the substance.

In the figure, 1 is an electret body having air permeability;
2.2' is a hood, 3 is air containing a specific substance, 4 is a specific substance, 5 is a supply device for the specific substance, 6 is an inlet air direction 6.7 is an exhaust air exhaust direction, 8 is an intake fan, 9 is the traveling direction of the electret body, 10 is the hopper,
Reference numeral 11 indicates an air suction port, and reference numeral 12 indicates the direction of air sucked into the electret body. It is possible to make the electret body adsorb onto the surface of the electret body.

That is, a certain amount of the specific substance is supplied to the air suction port by the supply device, and is dispersed at a certain concentration by the diffusion force of the air entering from the suction port. The air containing the specific substance passes through the electret body by the suction force of the intake fan, and during this passage, most of the specific substance is adsorbed and collected on the surface of the electret body due to the electrostatic force of the electret body. Of course, it is also collected on the surface of the electret body due to the mechanical separation effect.

As a result, the specific substance adsorbed on the surface of the electret body does not easily fall off due to its electrical adsorption effect, so that a functional electret material 13 having stable functions can be obtained.

Next, if the specific substance is a liquid or a specific substance dispersed in a liquid, it is possible to create minute droplets (mist) using a device that turns the liquid into droplets, such as a sprayer or an atomizer. After forming the electret body into droplets using a suitable device and dispersing the droplets in air, or after separating only the solid valve from the liquid through a dryer zone if necessary and dispersing it in air, the electret body is aerated. A functional electret body can be obtained by this method.

FIG. 2 is an example of an embodiment showing the method of forming droplets, and shows an example of an atomizer which is a device for turning a specific substance into a liquid or a specific substance dispersed in a liquid into a mist. This is a schematic diagram, and can be used in place of the specific substance supply portion in FIG. 1. In the figure, air 15 is sucked into a slit-shaped hole 21. On the other hand, the liquid specific substance 14 sucked by the pressurized air 16 is turned into a mist 20 and becomes the air 17 containing a certain concentration of mist, which is indicated by the arrow 18.
The electret body (not shown) is attracted to the electret body (not shown) downstream.

In the figure, one indicates a block, and arrows 15, 16, and 18 indicate the direction of air movement.

Next, FIG. 3, like FIGS. 1 and 2, is a schematic model diagram illustrating one embodiment of the method for producing a functional electret material of the present invention, and is An embodiment of a method for producing a functional electret material by spraying air containing a substance having an action function onto the surface of an electret body will be shown. In the figure, a specific substance 4 is supplied in a certain amount to a slit-shaped narrow air flow path 24 by a specific substance supply device 25, and is blown into the air by air sent into a duct 23 by a blower fan 22. The air 3 is dispersed and contains a specific substance, and is sprayed onto the surface of the electret body 1.

At this time, the specific substance is adsorbed to the electret body surface by the electrostatic attraction force generated from the electret body surface,
A functioning electret material 13 can be obtained.

Furthermore, the specific substance may be dried, concentrated, or fixed by heat treatment, if necessary, before or after spraying the specific substance onto the surface of the electret body.

Generally speaking, in order to improve the adsorption rate, a method in which a specific substance is charged in advance and then introduced into an electret body is extremely effective in increasing the adsorption effect.

To explain the state of adsorption of a specific substance obtained by the method of the present invention, the electret body has an electrostatic adsorption effect because lines of electric force are generated from the surface of the object due to its surface charge. By bringing powder or mist, which is a substance that has a physical or chemical function, close to the surface of the electret body, the powder or mist is electrically adsorbed to the surface of the electret body, and the electret body When the powder is made up of fiber lumps, it is adsorbed inside the boundary and cannot be easily released.If the powder or mist used has a specific function, It is possible to obtain a highly functional electret material that satisfactorily has specific functions as desired.

To explain in more detail the state of one-step adhesion of a specific substance to the surface of the electret body, if the substance is a powder, the electrolytically adsorbed substance will adhere to the surface of the electret body in a small amount. In general, there is a tendency for the particles to adhere in the form of dots; however, in the case of a large amount, powder particles tend to adhere on top of the adhered powder particles, forming a bead-like form of adhesion. This is a typical example.

Even when the substance is in the form of a lump, its adhesion form is
The same tendency as in the case of the powder described above is shown.

Generally, when the substance is a liquid mist or aerosol, it initially adheres to the surface of the electret body in dots, but as the mist spreads on the surface of the electret body, it tends to adhere to an irregular shape like an amoeba. It is in. In particular, when the electret body is a nonwoven fabric, when the above-mentioned mist-like substance is adsorbed, the amount of adhesion on the outer layer generally tends to be larger than the amount of adhesion on the inner layer. In addition, compared to the pad method, it tends to adhere to individual fibers in a relatively uniform amount, and there is virtually no tendency for particularly large amounts to adhere to the intersections of constituent fibers, and it is well dispersed. It exhibits good adhesion with good uniformity.

According to the method of the present invention, for example, an antibacterial agent can be used as a powder and electrostatically adsorbed onto an electret nonwoven fabric to obtain an excellent antibacterial electret nonwoven fabric, or as a powder and/or a mist. , bactericidal agents, deodorants, deodorizing agents, antifungal agents, fragrances, insect repellents, etc. can be used as appropriate and desired.

Further, as the substance to be adhered, in addition to powdered YAMIST, appropriate fibrous materials, lump materials, etc. can be used.

The surface charge density of the electret body used in the present invention must be 5X10-11 corons/d or more, and this is necessary in order for the electrostatic adsorption effect to work well on the above-mentioned powders, mist, etc. If it is less than 5 x 10" coulomb/-, the electrostatic adsorption effect is small, and the attached substance may fall off and the desired function cannot be fully exerted, which is undesirable. Particularly preferably used in the present invention. The electret body has a surface charge density of 2×1o-
It is 10 colon/d or more.

It should be noted that an appropriate binder may also be attached by electroadsorption along with the above-mentioned powder or mist. In this way, substances that have a chemical or physical action function can be attached in addition to the electroadsorption action. , the adhesive force is also applied by the action of the binder, making it possible to maintain a stronger adhesion state.

The material of the electret body is not particularly limited, and various materials such as film, microporous film, knitted woven fabric, nonwoven fabric, or thread-like material can be used depending on the purpose, but among them, Melt-blown nonwoven fabrics and spunbond non-MA fabrics made of polypropylene fibers are preferably used in terms of their performance and ease of manufacture.

In addition, the substance having a specific chemical or physical action function that causes the electret body to be adsorbed is not limited to one type, but multiple types of substances may be adsorbed, and such two or more types may be adsorbed. An electret body formed by adsorbing a substance can easily be made into a high-performance electret material that has two or more types of functions at the same time.

In the present invention, a substance having a chemical action function is a substance that can bring about a chemically active action, and refers to a chemical agent or chemical substance having the above-mentioned function, such as 3-trimethoxysilyl. -Propyl-dimethyl-
The chemical octadecyl-ammonium chloride has excellent antibacterial properties, and DDT and BHC have excellent insect repellent properties. Activated carbon also has deodorizing properties. In addition, substances that have a physical action function are substances that can bring about physical activation, such as things that generate magnetic force like magnets, or things that change hue when they sense changes in temperature. It is something.

Note that the amount of a specific functional substance deposited varies depending on the desired function, but according to the various findings of the present inventors, for example, if the substance is intended to have antibacterial properties, generally It is best to set it within the range of about 0.05 to 5.0 CI/12. On the other hand, if the purpose is to have deodorizing properties, it is generally recommended to set it within the range of about 0.1 to 10 Q/m2. good.

In addition, in the present invention, the measurement of the surface charge density described above is carried out in the fourth step.
This is done using the method shown in the figure.

That is, in FIG. 4, a grounded metal box 26 and a metal flat electrode (area: 1 (10o+f, material: brass)
A sample 28 is sandwiched between 27, and the voltage generated by electrostatic induction is measured by an electrometer 30 via a capacitor 29, and the surface charge density is determined from the measured potential using the following calculation formula. It is.

Q=CXV/S Q: surface charge density (coulombs/clTf) C: capacitor capacity V: voltage S: area of sample (art) [Example] Based on the example, the structure of the functional electret material of the present invention will be explained below. , the effects will be explained in detail.

Example 1 Treatment solution of 3-trimethoxysilyl-propyl-dimethyl-octadecyl-ammonium chloride (a degree 10%
) is used to create a mist using the method shown in FIG.
The antibacterial agent was added at 0.3 g/Tr12 by flask method (ATO).
04352), and the sterilization rate was evaluated using the following formula using Talepsilla pneumonia.

Sterilization rate (%>=2L-Yx 1o.

X Number of bacteria after 20 hours Y: Number of bacteria after 1 hour culture As a result, the sterilization rate is 1 (10%), which is very good and also has good performance as an electret body. Met.

Comparative Example 1 The sterilization rate of the electret nonwoven fabric (no antibacterial treatment) used in Example 1 was evaluated in the same manner as in Example 1 without any antibacterial agent attached, and the sterilization rate was 40%.
This was completely inferior to that described in Example 1.

Example 2 Activated carbon (PK350# manufactured by Kuraray Chemical ■) was dispersed in the air at a rate of 3 g/m', and a polypropylene electret filter (fineness 4 denier, surface charge density 3 x 10" coulombs/-1 basis weight 2 (10 g /lT1
2) (thickness 1.7 mm) was aerated to obtain an electret nonwoven fabric having a deodorizing function and an activated carbon adhesion amount of 5 g/-.

When we created a filter element using this electret nonwoven fabric and used it as a ventilation filter in an animal housing, we were able to confirm that it was a ventilation filter that very effectively reduced animal odors.

Example 3 Polypropylene electret material with surface charge density 3.0 x 10-10 coulombs/Tn2 (fineness 0.05 denier, basis weight 50 g/Tr12, air flow rate 70cc10yF.
sec), 60% of the deodorant (Fresh Shiraimatsu FS-5 (10M) manufactured by Shiraimatsu Shinyaku
CI/α and 40 g/fl of boron MF50 (manufactured by Shin-Etsu Chemical) containing 40% of 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride as an antibacterial substance, urethane emulsion (Bondic 1610 manufactured by Dainippon Ink Co., Ltd.) , solid content: 40%), create a mist containing a specific substance at a concentration of Ig/m' using an atomizer, ventilate it to the electret sheet, and apply the deodorizing substance and antibacterial agent to the electret sheet's surface area. It was dried at a temperature of +160° C. to which 1% by weight of the odor substance and 0.5% by weight of the antibacterial agent were deposited.

The ventilation volume of the functional electret material after processing is 70 cc
/-・sec, there is no change, and the surface charge density is roughly 3.
There was no change at 0x10'' coulomb/-.

The deodorizing properties of this sheet were evaluated by the following method.

1 cc of trimethylamine was placed in each of three 350 cc sealant frusts. Next, a functional electret sheet and an unprocessed electret sheet (20 cm
x 25 cm> was placed in the flask (1 piece/1 flask). After leaving each sample for 1 hour, 1 cc of head spacing gas was taken into a gas chromatograph analyzer, and the removal rate for each sample was determined using the following formula.

As a result, the removal rate of raw electret material is 4
However, the functional electret material obtained by the method of the present invention was 99%.

Next, antibacterial properties were evaluated by comparing the unprocessed electret material and the functional electret material according to the present invention using the shake flask method.

The bacteria reduction rate was 40% for the unprocessed electret material, whereas it was 99% or more for the functional electret material obtained by the method of the present invention.

Comparative Example 2 The polypropylene electret material used in Example 3 was immersed in the chemical containing the specific substance used in Example 3, squeezed with a mangle, and then dried (1 (10° C. x 5 minutes)).

The adhesion of the specific substance to this sheet exceeded 5% by weight.

The airflow rate is less than 10cc/-sec, which is no longer suitable as a filter, and the surface charge density is 1X1.
It was found that the electronitredolinity decreased significantly below 0-'' coulomb/-.

Example 4 An antibacterial agent and a low melting point powder (H4011) manufactured by Tetsusei Kagaku Co., Ltd. were applied to the surface of a polypropylene electret melt-blown nonwoven fabric (average fiber diameter 2.4 μm, basis weight 20 g/m2, surface charge density 6.0×10-10 coulombs/Ca). :
A powder mixed at a ratio of 0.1 to 10 was sprayed onto the surface of the electret nonwoven fabric using the method shown in Figure 3, and an antibacterial agent was added at 0.1.
After adhering Q/m2, heat treatment was performed at 60°C to dissolve the low melting point powder and stably fix the antibacterial agent to the surface of the nonwoven fabric.

The antibacterial properties of this sheet were evaluated for sterilization rate in the same manner as in Example 1, and the sterilization rate was 85% or more.

On the other hand, the unprocessed sheet was 40%, confirming the effectiveness of the functional electret sheet obtained by the method of the present invention.

[Effects of the Invention] According to the present invention as described above, powders, droplets, fibrous materials, etc. that have a specific chemical action function or physical function are produced based on the electrostatic adsorption effect of the electret. By adhering to the surface of the electret body, it is possible to easily produce an electret material that retains approximately 1 (10%) of the functions of the powder, ghost mist, droplets, and fibrous material. can.

That is, according to the present invention, a substance having a specific action function is adsorbed on the electret surface without using a binder or other adhesive, so that the function of the substance can be highly enhanced and the characteristics of the electret can be improved. It can be effectively utilized without substantially impairing air permeability or impairing air permeability. In particular, when the binder is also electrically adsorbed and the substance is attached, a very high adhesion force can be obtained.

In addition, electret bodies that have adsorbed substances with various specific functions can easily be made into electret materials that have multiple functions at the same time, such as antibacterial, antifungal, and deodorizing properties. It is also easily possible to provide various types of multiple functionalities that are desirable to coexist, such as a combination of the following.

Therefore, if the sheet processed by the method of the present invention is applied to a mask, for example, it is possible to obtain an antibacterial mask, a deodorizing mask, an aromatic mask, etc. that satisfy electret properties, breathability, etc. Furthermore, if antibacterial treated material is used as a cover material for animal breeding cages, it will be useful for protecting animals from infection. Furthermore, if used as a surgical drape, it can be used as a material that helps protect doctors from infection.

According to the present invention, it is possible to impart various desired functions without causing a decrease in electret properties or changing the initial physical properties of the electret body (sheet strength, elongation, air permeability), etc. It is.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams each showing an example of an embodiment of the method for producing a functional electret material of the present invention as a model, and FIGS. 1 and 2 contain specific substances. A method is shown in which air is sucked into the electret material, and FIG. 3 shows a method in which air containing a specific substance is sprayed onto the surface of the electret material. FIG. 4 is a schematic model diagram illustrating a method for measuring surface charge density. 1: Electret body 2 and 2'2 hood 3: Air containing a specific substance 4: Powder, lump, or fibrous substance that has a chemical or physical action function (specific substance) 5: Specific substance supply device 6: Suction air 7: Exhaust air 8: Intake fan 9: Direction of movement of the electret body 10: Hopper 11: Air suction port 12: One direction of air sucked inside the electret body 13: Functional electret material 14: Liquid Specific substance 15: Suction air 16: Pressurized air 17: Air containing specific substance 18: Direction of movement of air containing specific substance 19 Ni block 20: Mist 22: Blower fan 23: Duct 24: Air flow path 25: Specific substance supply Device

Claims (10)

[Claims] (1) Introducing a gas containing a substance having a chemical action function or a physical action function into or near an electret body with a surface charge density of 5 × 10^-^1^1 coulombs/cm^2 or more. A method for producing a functional electret material, characterized in that the substance having the chemical action function or the physical action function is attached by the electroadsorption action of the electret body. (2) The method for producing a functional electret material according to claim (1), wherein the electret body is made of a nonwoven fabric of synthetic fibers. (3) Claim (1) or (3) characterized in that the nonwoven fabric is a synthetic fiber melt-blown nonwoven fabric.
2) The method for producing the functional electret material described in section 2). (4) Claims (1) and (2) characterized in that the nonwoven fabric is made of polypropylene fibers.
The method for producing a functional electret material according to item 2) or item (3). (5) Claims (1) and (1) characterized in that a gas containing a substance having a chemical action function or a physical action function is introduced into or near the electret body by a suction flow. The method for producing a functional electret material according to item (2), item (3), or item (4). (6) Claim (1), characterized in that a gas containing a substance having a chemical action function or a physical action function is introduced into or near the electret body by a blowing flow; The method for producing a functional electret material according to item (2), item (3), or item (4). (7) Claims (1), (2), (3), and (3) in which the substance having a chemical action function or a physical action function is an antibacterial substance. The method for producing a functional electret material according to item (4), item (5), or item (6). (8) Claims (1), (2), and (3), characterized in that the substance having a chemical action function or a physical action function is an antifungal substance; No. (4)
A method for producing a functional electret material according to item (5) or item (6). (9) Claim (1) characterized in that the functional electret material is for filter material.
(2), (3), (4), (5), (6), (7) or (8). Production method. (10) Claim (1), characterized in that the functional electret material is for dustproof material;
The method for producing a functional electret material according to item (2), item (3), item (4), item (5), item (6), item (7), or item (8). .