JPH08284063A - Electret sheet, its production and filter substrate - Google Patents

Abstract

PURPOSE: To form an electret sheet having high surface charge density in spite of a formed resin article and to obtain a filter having low pressure drop and high collection efficiency by using the sheet as the substrate. CONSTITUTION: A resin composition is produced by compounding a chlorinated polyolefin resin having a chlorine content of >=50wt.% with >=0.1wt.% of a functional agent consisting of at least one substance selected from antibacterial agent, antifungal agent, deodorant, perfumery, colorant, insecticide, water- repellent, ultraviolet absorber and heat stabilizer, e.g. a combination of an antibacterial agent and an antifungal agent. The above resin composition is applied by spraying, coating or impregnation to a composite sheet produced by laminating two or more layers of melt-blown polypropylene sheet having a bending resistance of >=15cm measured by 45 deg.C cantilever method or laminating a cloth to the above melt-blown sheet and the applied resin is dried. The amount of the resin composition is 0.3-10wt.% based on the weight of the fiber. The dried product is subjected to an electret-forming treatment to obtain an electret sheet having a surface charge density of >=1×10<-10> coulomb/cm<2> .

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electret sheet having a high surface electrification density even though it is a resin processed product, and further has an electret function at the same time as the functionality such as antibacterial property and mildewproof property, particularly a nonwoven fabric, It also uses the characteristics of meltblown nonwoven fabric,
In particular, the present invention relates to an electret sheet suitable for use in a filter, particularly in the field of air-conditioning filters such as cabin filters, a manufacturing method thereof, and a filter substrate.

[0002]

2. Description of the Related Art In general, a nonwoven fabric, particularly a melt-blown nonwoven fabric, is made by blowing a thermoplastic resin into a fibrous shape to collect it into a sheet and form a sheet. A sheet having the constitution can be easily obtained and is suitable as a filter. In particular, the electret-processed one has a low pressure loss and a high collection property, and has come to be widely used in the field of filters.

As an example of imparting antibacterial or antifungal properties to an electret-processed meltblown nonwoven fabric, one kind selected from aromatic halogen compounds, silicon quaternary ammonium salts and organometallic compounds as an antibacterial agent for fiber sheets. An example in which the above is adhered via a melamine resin and then subjected to electret processing is disclosed in JP-A-62-2.
Although it is proposed in Japanese Patent Publication No. 82077, there is a defect that the surface charge density and the antifungal performance are inferior.

Further, in JP-A-1-164411 and JP-A-1-187918, the characteristics of the electret sheet are utilized, and the adsorption phenomenon is used to adsorb antibacterial and antifungal agents together with the low melting point powder. Although an example of fixing by heat treatment has been proposed, there is a drawback in that electret performance is deteriorated by low melting point powder or heat treatment.

Although there is an example in which an antibacterial and antifungal agent is kneaded into a polymer to form a melt-blown nonwoven fabric, there is a problem that the antibacterial and antifungal agent is easily decomposed by heat during manufacturing. Further, in Japanese Utility Model Laid-Open No. 6-57412, there is an example in which a fungicide is adhered to only one surface of a non-woven fabric through a vinyl chloride resin such as melt blow, but the performance of a layer to which the fungicide is not adhered is difficult. Japanese Unexamined Patent Publication No. 62-42715 proposes a composite material for an electret filter in which at least one surface of a non-woven fabric for an electret filter is processed with an antibacterial agent, and in Japanese Unexamined Patent Publication No. 62-42716.
Although a material for a non-woven fabric electret filter in which an antibacterial synthetic fiber is made into an electret has been proposed, all of them have a drawback that they are inferior in surface charge density and performance such as mold resistance.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides an electret sheet having a high surface electrification density, which is a resin processed product, and a higher level of surface charge density and functionality, which cannot be obtained by the conventional techniques. It is intended to provide an electret sheet that simultaneously satisfies antibacterial properties and fungicidal properties, and a method for manufacturing the electret sheet. Moreover, a suitable filter material particularly suitable for the filter field, especially air taken in a room such as a cabin filter is used. The purpose of the present invention is to provide a high-performance filter base material for making it refreshing.

[0007]

In order to achieve the above object of the present invention, the following constitution is adopted.

That is, the electret sheet of the present invention is a sheet to which a chlorinated polyolefin is added, and the sheet has a surface charge density of 1 × 10 ^-10 coulomb / cm ² or more. In addition, the sheet is provided with a resin composition containing a functional agent and a chlorinated polyolefin,
Moreover, the sheet has a surface charge density of 1 × 10 ⁻¹⁰ coulomb / cm ² or more.

Further, the method for producing a functional electret sheet of the present invention is characterized in that after the chlorinated polyolefin is applied to the sheet, electret processing is performed. Further, the filter substrate of the present invention is characterized by being constituted by such an electret sheet.

[0010]

The effect of the present invention is that the surface charge density of the electret sheet and the various functions of resin products and functional products such as antibacterial and antifungal properties can be produced at a high level. Has reached a specific resin called chlorinated polyolefin. That is, this resin has a completely different function from ordinary resins such as melamine resin and vinyl chloride resin, that is, the chlorinated polyolefin supports the surface electrification density of the electret sheet at a high level. In addition to having the characteristics, the function of a functional drug is directly expressed,
It has been found that the adhesiveness to fibers is excellent, and in the electret processing in the post-processing, it exerts a function of improving the surface charge density of the sheet and the fibers constituting the sheet, and arrived at the present invention. It is a thing.

That is, according to the present invention, although it is a resin processed product, while sufficiently exhibiting the performance of the functional drug, it is 1 × 10 ^-10 coulomb / cm ² or more, and further 1 × 1.
Surface charge densities as high as 0 ^-9 coulombs / cm ² and up to 1 × 10 _-8 coulombs / cm ² can be achieved.

The chlorinated polyolefin referred to in the present invention is
Polyolefins such as polyethylene, polypropylene and polybutylene are chlorinated in a solution or suspension of carbon tetrachloride, chloroform, trichloroethylene, etc., but the chlorine content is chlorinated up to about 30%, For example, polyethylene is softer and more rubber-like than polyethylene itself, and is soluble in a solvent, but it has the characteristic of increasing in hardness as chlorination progresses. Those with advanced chlorination are unstable to light and heat and generally contain stabilizers. In the present invention, of such chlorinated polyolefin, preferably at least 5% by weight, more preferably 10 to 40% by weight.
A chlorinated polyolefin is often used in an amount of 15% by weight, particularly preferably 15 to 25% by weight.

The chlorinated polyolefin is used by dissolving it in a solvent which is usually used as a solvent such as toluene, xylene, methyl ethyl ketone, dimethyl formaldehyde and the like. At this time, a dispersion system, that is, a dispersion system or an emulsion system using a dispersant or an emulsifier is not preferable because it causes a drawback that the surface electrification density is remarkably lowered.

Such a chlorinated polyolefin has a high level of surface electrification density, unlike conventional resin processing, even if it is applied (sprayed, coated, impregnated) to a sheet material such as a cloth or a film and then converted into an electret. It has the feature of providing an electretized sheet. On the other hand, ordinary resin processed products of synthetic resins such as melamine resin, vinylidene chloride and vinyl chloride resin prevent electretization and can only produce electretized sheets having a low surface electrification density. Therefore,
The most feature of the present invention is that such a chlorinated polyolefin resin-treated sheet (including cloth, film and composite thereof) has a high level surface of 1 × 10 ^-10 coulomb / cm ² or more as described above. The point is that an electret sheet having an electrification density can be provided. Such characteristics are achieved by knitted woven fabrics, non-woven fabrics, films and composite sheets thereof, irrespective of the form of the electret sheet, and a chlorinated polyolefin is applied to these sheets by means such as coating or impregnation, and further spraying. After that, if necessary, it can be dried and electretized.

The chlorinated polyolefin is an antibacterial agent,
Antifungal agent, deodorant, fragrance, colorant, insect repellent, water repellent,
When a resin composition is formed by blending a functional agent such as an ultraviolet absorber or a heat stabilizer, it is possible to achieve a high level of surface electrification density while achieving each of the functions of the functional agent. It achieves the amazing effect of being able to. The amount of such a functional agent blended is preferably at least 0.1% by weight, more preferably 0.2.
˜50 wt%, and particularly preferably 0.5 to 20 wt%, is preferably added to the chlorinated polyolefin, but the amount to be added is appropriately changed depending on the type and purpose of the functional drug. . However, the proportion of the chlorinated polyolefin in the resin composition is preferably at least 10% by weight, and the larger the proportion, the more excellent the durability and the surface electrification density can be provided. The resin composition in which such a functional agent is mixed with chlorinated polyolefin,
For the electret sheet, for example, the fiber weight,
Preferably 0.3 to 10% by weight is applied to the sheet. In addition, as the functional drug, a commonly used known drug can be used.

For example, in such an electret sheet,
When it is desired to form a filter substrate, an antibacterial agent, an antifungal agent, a deodorant, etc. are selected as the functional agent, and the resin composition is prepared by blending with a chlorinated polyolefin.

For example, as the antibacterial agent component to be used, a basic group containing an amidine group or a guanidine group, or a compound such as a sodium salt, potassium salt or ammonium salt thereof can be used.

As the compound containing an amidine group,
4,4'-stilbene-dicarboxamidine-diisethionate (stilbamidine isethionate), N '
-(4-chloro-2-methyl-phenyl) -N, N-dimethyl-metaminide (chlordimeform) u, etc.,
Examples of the compound containing a guanidine group include 1,17-diguanidino-9-aza-heptadecane (azatine), P
-(Chlorophenyldiguanide) -hexane (chlorhexidine), P-benzoquinone-amidino-hydrazone-thiosemicarbazone (ambazone) and the like can be mentioned, but these compounds are examples, and compounds other than the above can be used. Needless to say.

Of the above compounds, P- (chlorophenyldiguanide) -hexane or a salt thereof is particularly desirable because it has high safety and does not deteriorate antibacterial properties even in the presence of proteins and the like.

The antifungal agent used together with the above antibacterial compound is N-n-butylcarbamic acid 3-effective particularly effective against black mold.
It is preferable to use 9-iodo-2-propynyl ester (mold inhibitor 1), 2- (4-thiazolyl) benzimidazole, which is particularly effective against mildew, and its salt (mold inhibitor 2) as main components. These antifungal agents may be used in combination with generally known antifungal agents.

A coating resin is used as a means for fixing the above-mentioned antibacterial agent and antifungal agent to the melt blown sheet. A highly hydrophobic resin is preferable as this resin, and an olefin resin is desirable. Particularly preferred are chlorinated olefins or those containing chlorinated olefins as a main component.

As a preparation liquid for coating the melt blown sheet with the antibacterial agent, antifungal agent and coating resin, there are organic solvent, a method of emulsifying and suspending an aqueous solution, and the like, and a method of dissolving with an organic solvent is adopted. The necessity is important for the uniformity of the coating process and the maintenance of the electret process effect.

As the organic solvent for adjusting the processing amount and workability, general-purpose solvents such as toluene, xylene, methyl ethyl ketone, and dimethylformaldehyde may be used alone or in combination, but there is no particular limitation, but from the viewpoint of workability, toluene, xylene, etc. Is a good example, and evenly spreads over the entire surface of the melt blown sheet from the processed surface, and there is little unevenness in the adhesion amount. Further, it is also preferable in that no antibacterial agent, antifungal agent, additives other than coating resin, emulsifier, etc. remain after drying.

By adjusting the concentration of the antibacterial agent, antifungal agent, coating resin formulation, and adjusting the wet pickup processing amount, the wet pickup amount is adjusted to about 50 to 300%, and 500 poise of clay is used to uniformly penetrate the meltblown sheet. Below, the amount of adhesion after drying is preferably in the range of 0.2 to 10% in terms of processing.

If the adhered amount is 0.2% or less, the antibacterial and antifungal effects are weakened, and if the adhered amount is 10% or more, a coating is formed between the fibers, so that the gap between the fibers is reduced. As a result, the pressure loss increases, which is not preferable as a filter. For this reason, it is desirable to set the amount of adhesion to 0.5 to 5%.

The ratio of the components is 5 to 50 for the antibacterial agent.
%, 0.5-20% of antifungal agent 1, 0.2 of antifungal agent 2
-10%, coating resin 10-94.3% of the remaining amount
And

When the coating resin component ratio is high, the antibacterial agent and antifungal agent are embedded in the resin, and the antibacterial and antifungal effects are weakened. Therefore, the coating resin component is preferably about 25 to 75%, more preferably 30 to 70%. There are gravure coating method, knife coating method, roll coating method, dip nip method, dipping method, spray method, etc. as the processing method for coating the blended solution on the melt blown sheet. The gravure coating method and the spray method, which take into consideration weakness against loads such as friction and tension because they are drawn yarns composed of fine fibers, are preferable because a large load is not directly applied to the melt blown sheet. The gravure coating method is more preferable because of the uniformity of processing.

Thus, it is important to completely remove the solvent by drying the melt blown sheet to which the preparation liquid is attached at 50 to 100 ° C. for about 30 to 180 seconds.

When the structural difference is large, such as in a laminated product, there is no problem even if this processing is repeated or the coating surface is inverted and repeated.

The melt blown sheet is antibacterial and mildew proof, and any generally known thermoplastic polymer can be used. However, as the high-performance filter material, polypropylene having stable electret performance is preferable.

When used as a filter material, the polypropylene melt blown sheet may be a single substance, but a plurality of layers of the polypropylene melt blown sheet may be laminated, or a spun pond and a synthetic resin net may be laminated.
In any of these cases, it is not desirable to add a hydrophilic substance such as an oil agent, and polypropylene spun pond, polyolefin synthetic resin net, etc. can be laminated with the melt blown sheet.

The laminating method may be a commonly known ordinary method such as a heat-adhesive binder or hot embossing, but it is desirable to supply the laminating material to a melt-blowing cloth making line and directly laminate it with the melt-blowing sheet. It is preferable because it is high, the permeability of the coating resin preparation liquid is increased, and the adhesion amount is less uneven.

The melt blown sheet is used as a filter base material by pleating it and processing it into a unit, which is naturally subjected to air resistance during use. When the filter base material is deformed by this force, the structural pressure loss of the unit increases. Therefore, the rigidity to withstand this must be 15 cm or more by the 45-degree cantilever method. Preferably 18 cm
More preferably, it is 20 cm or more.

The thus-obtained antibacterial and antifungal processed melt blown sheet has an antibacterial and antifungal effect, but is not outstanding as a filter filter material and has a mechanical collection performance depending on the fineness of the melt blown sheet. .

The above-mentioned structure of the melt-blown sheet, antibacterial and antifungal treatment is performed by placing the melt-blown sheet on a conventionally known earth electrode and subjecting it to electretization for about 5 to 60 seconds in a high DC voltage of about 10 kv / cm. Antibacterial, mildew-proof and electret melt blown sheets can be obtained, and the surface charge density is usually 1 × 10 ^-10.
It shows coulomb / cm ² or more, and may show a value as high as 1 × 10 ⁻⁸ coulomb / cm ² .

The method of measuring the surface charge density in the present invention will be described with reference to FIG. That is, in FIG. 1, the grounded metal box 1 and the metal plate electrode (area 100 c
The sample 3 is sandwiched between m ² and the material: brass) 2, the voltage generated by the electrostatic induction is measured by the electrometer 5 through the capacitor 4, and the measured potential is calculated according to the following formula. This is to obtain the surface charge density.

Q = C × V / S where Q: surface charge density (coulomb / cm ² ) C: capacitor capacity V: potential S: plate electrode area

[0038]

EXAMPLES The contents of the present invention will be described below in more detail with reference to examples, but the present invention is not limited to the examples and processes. The measuring method in the present invention is shown below. Fineness: In the present invention, the fineness is 50 using an electron micrograph.
The width of the side surface of the fiber photograph magnified 0 times and 1000 times was measured at random at 300 pieces, and is shown as the median diameter.

Antibacterial test: Hello test (AATCC-90
test) (Staphylococcus aureus).

The state of the growth inhibition zone (halo) is observed.

Antifungal test: Cultured at 28 ° C. for 14 days by JIS Z2911 medium method.

The molds of the fungi in the culture were observed for the growth state of Aspergillus niger, Penicillium citrinum, Cladosporium cladsporioides, and Alternaria alternata.

Examples 1 to 4 Polypropylene melt blown sheet having a fineness of 1.3 μ and a basis weight of 30 g / cm ² (Example 1), fineness of 2.8 μ and a basis weight of 50 g / cm ²
cm ² polypropylene melt blown sheet (Example 2), polypropylene melt blown sheet having a fineness of 8.5 μm and weight of 60 g / cm ² laminated with polypropylene melt blown sheet having a fineness of 15 μm and weight of 80 g / cm ² (Example 3), basis weight A fineness of 6.5μ and a basis weight of 6 on both sides of an olein-based synthetic resin net with 15g / cm ² and a mesh of 4mm.
A 0 g / cm ² polypropylene melt blown sheet laminated sheet (Example 4) was prepared.

As an antibacterial agent, antifungal agent and coating resin formulation, 6 parts of P- (chlorophenyldiguanide) -hexane as an antibacterial agent and Nn butylcarbamic acid 3-9 iodo-2 as an antifungal agent. 2 parts of propynyl ester (mold inhibitor 1), 1 part of 2- (4-thiazolyl) benzimidazole (mold inhibitor 2) as a mold inhibitor, chlorinated polyolefin (15.8 wt% chlorinated polypropylene) 8 parts, toluene was used as a solvent, the solution concentration was adjusted, and the dry pickup amount was adjusted to 1.5%.

The coating of the preparation liquid was processed by gravure coating M / C and dried at 80 ° C. for 60 seconds to completely remove the solvent.

The melt blown sheet, which has been subjected to the antibacterial and antifungal treatment, is placed on the ground electrode and the melt blown sheet is placed 35
It was electretized for 5 seconds in a DC high voltage of kv / 5 cm.

The results of measuring the surface charge density of these sheets by the electrostatic induction method were as follows, and good electret sheets were obtained.

Example 1 8.5 × 10 ⁻⁹ Coulomb / cm ² Example 2 5.4 × 10 ⁻⁹ Coulomb / cm ² Example 3 1.0 × 10 ⁻⁹ Coulomb / cm ² Example 4 5. 8 × 10 ^-10 coulomb / cm ² As a result of carrying out a halo test as a test for these antibacterial properties, a halo, which is a growth-inhibitory zone of Staphylococcus aureus, was clearly expressed and the effect was recognized.

As a test for antifungal property, JIS Z
It was conducted by the 2911 double ground method.

There was no growth of any mold, and excellent mold resistance was exhibited.

The seat 1, seat 2, seat 3 and seat 4 are pleated, seat 1 and seat 2 are used as an indoor air conditioning filter, seat 3 and seat 4 are used as cabin filters, and seat 2 and seat 3 are vacuum cleaner filters. As a result, when the sheet 1 was used as a wiper, it exhibited antibacterial and antifungal effects for a long period of time, and no generation of germs, mold, and odor were observed.

Regarding the collection performance of the filter, the collection efficiency maintained the initial performance and almost no decrease in the surface charge density was observed.

Comparative Examples 1, 2 and 3 In contrast to Example 1 above, when the antibacterial agent was removed from the coating resin formulation of the processing agent (Comparative Example 1) and the antifungal agent 1 was removed (Comparative Example 2) ), The electret sheet was obtained by the same processing method as in the example, except that the antifungal agent 2 was removed (Comparative Example 3).

The surface charge density was almost the same,
In the case of Comparative Example 1, although excellent fungicidal properties were exhibited, the halo test growth inhibition zone was not developed.

In Comparative Examples 2 and 3, the halo, which is a growth inhibition zone, was clearly expressed and the effect was recognized, but in Comparative Example 2, black mold growth was observed in the antifungal test, and Comparative Example 3 white. There was mold growth and the mold resistance was insufficient.

Regarding Example 1 above, the amount of toluene solvent of the coating resin of the processing agent was adjusted, and the dry pickup amount was adjusted to 0.1% (Comparative Example 4) and 15% (Comparative Example 5). Processed.

In Comparative Example 4, halo, which is a growth inhibition zone, was slightly developed, and in the mildew proof test, black mold,
The development area where white mold was mixed became more than half of the total area, and both antibacterial and antifungal properties were insufficient.

In Comparative Example 5, both the antibacterial and antifungal properties were good as in Example 1, but a resin film was formed between the fibers, the air permeability was lost, and the pressure loss was increased. Insufficient melt blown sheet.

Examples 5 and 6 A polypropylene meltblown sheet of Example 1 having a fineness of 1.3 μ and a basis weight of 30 g / cm ² (Example 5), and a basis weight of 15 g / cm ² of Example 4 having a mesh roughness of 4 mm. A polypropylene melt blown sheet having a fineness of 6.5μ and a basis weight of 60 g / cm ² was laminated on both sides of an olein-based synthetic resin net (Example 6), and 15.8% by weight of each of these sheets was prepared.
A resin solution prepared by dissolving chlorinated polypropylene in toluene was prepared so that the dry pickup amount was 1.5% by weight.

Gravure coating M / C
Was coated and dried at 80 ° C. for 60 seconds to completely remove the solvent.

The two resin-coated products were each subjected to electret treatment for 5 seconds in a high DC voltage of 35 kv / 5 cm by placing a melt blown sheet on the ground electrode in the same manner as in Example 1.

The surface charge densities of these sheets were measured by the electrostatic induction method. As a result, Example 5 was 9.0 × 10 ^-9 coulomb / cm ^{2 and} Example 6 was 1.5 × 10 ^-9 coulomb / cm ² . All showed higher values than those of Examples 1 and 4.

[0063]

INDUSTRIAL APPLICABILITY The present invention can provide an electret sheet having a high surface electrification density even though it is a resin processed product, and has a higher level of surface charge density and functionality such as antibacterial property and protection. It is possible to provide an electret sheet that satisfies moldiness at the same time, and it is a suitable filter material especially suitable for the filter field, in particular, it has low pressure loss but high collection performance, so it is used for building air conditioners, cabins, vacuum cleaner filters, etc. As in the above, the air taken in the room can be refreshed and a comfortable environment can be provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a method for measuring the surface electrification density of an electret sheet.

[Explanation of symbols]

 1: Metal box 2: Metal plate electrode 3: Sample 4: Capacitor 5: Electrometer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08K 5/205 C08K 5/205 5/43 KFH 5/43 KFH C08L 23/28 C08L 23/28 D04H 1/72 D04H 1/72 A 3/00 3/00 Z

Claims (20)

[Claims] 1. An electret sheet which is a sheet to which a chlorinated polyolefin is applied and which has a surface charge density of 1 × 10 ⁻¹⁰ coulomb / cm ² or more. 2. The electret sheet according to claim 1, wherein the sheet is a woven or knitted fabric, a nonwoven fabric, a film, or a composite thereof. 3. A sheet provided with a resin composition containing a functional agent and a chlorinated polyolefin, the sheet having a surface charge density of 1 × 10 ⁻¹⁰ coulomb / cm ² or more. An electret sheet characterized by having. 4. The chlorinated polyolefin is at least 5
The electret sheet according to claim 1 or 3, which contains chlorine by weight. 5. The electret sheet according to claim 3, wherein the resin composition contains at least 0.1% by weight of the functional agent. 6. The resin composition contains 0.3% by weight of the fiber.
The electret sheet according to claim 3, which is applied to the sheet in an amount of 10 to 10% by weight. 7. The functional agent is an antibacterial agent, antifungal agent, deodorant, fragrance, colorant, insect repellent, water repellent, ultraviolet absorber,
The electret sheet according to claim 3, which is at least one selected from heat stabilizers. 8. The electret sheet according to claim 3, wherein the functional agent is the following antibacterial agent and antifungal agent. A: Antibacterial agent containing either amidine group or guanidine group B: Nn butylcarbamic acid 3-9 iodo-2-propynyl ester (mold inhibitor 1) C: 2- (4-thiazolyl) benzimidazole ( Antifungal agent 2) 9. The resin composition according to claim 8, wherein the functional agent having the following compounding ratio is added to the chlorinated polyolefin 10 to 10.
An electret sheet made by blending to 95% by weight. A: 5 to 50% by weight B: 0.5 to 20% by weight C: 0.2 to 10% by weight 10. The electret sheet according to claim 1, wherein the sheet is a melt blown sheet. 11. The electret sheet according to claim 10, wherein the meltblown sheet is polypropylene fiber. 12. The electret sheet according to claim 10, wherein the melt blown sheet has a bending resistance of 15 cm or more as measured by a 45 ° cantilever method. 13. The electret sheet according to claim 1, wherein the sheet is a laminate of two or more layers. 14. The electret sheet according to claim 1, 3 or 10, wherein the sheet is formed by laminating a cloth. 15. The electret sheet according to claim 7, wherein the antibacterial agent is P- (chlorophenyldiguanide) -hexane or a salt thereof. 16. A method for manufacturing an electret sheet, which comprises applying a chlorinated polyolefin to a sheet and then performing electret processing. 17. The method for producing an electret sheet according to claim 16, wherein the chlorinated polyolefin is a resin composition containing a functional agent. 18. The method for producing an electret sheet according to claim 16, wherein the applying method is spraying, coating or impregnating. 19. The method for producing an electret sheet according to claim 16, wherein the electret processing is performed after a drying step. 20. A filter base material comprising the electret sheet according to any one of claims 1 to 15.