JP5357658B2 - Composite fiber sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonwoven fabric sheet that exhibits a high antimicrobial action while reducing the amount of inorganic antimicrobial agent fine particles used, has excellent collecting properties of harmful microorganisms and dust, low pressure loss and excellent filter performance. <P>SOLUTION: The composite fiber sheet is obtained by laminating a nonwoven fabric layer (A) composed of a polyolefin (PO) fiber (a) made of a PO composition containing inorganic antimicrobial agent fine particles to a nonwoven fabric layer (B) composed of PO fiber (b) not containing inorganic antimicrobial agent fine particles in which the content of the inorganic antimicrobial agent fine particles in the PO fiber (a) is 5-20 mass%, the average particle diameter of the PO fiber (a) is 0.1-3 &mu;m, the weight of the layer (A) is 0.1-5 g/m<SP>2</SP>and the thickness of the layer (A) is 0.01-0.1 mm. The composite fiber sheet has one or more parts in which &ge;1/100 of the volume of the inorganic antimicrobial agent fine particles is exposed to the surface of the PO fiber (a) based on the area of the layer (A) of 1.0&times;10<SP>-2</SP>mm<SP>2</SP>or has one or more parts in which the inorganic antimicrobial agent fine particles are exposed to the surface of the PO fiber (a) in the area of &ge;0.01 &mu;m<SP>2</SP>. The average fiber diameter of the PO fiber (b) is 0.5-10 &mu;m, the weight of the layer (B) is 5-30 g/m<SP>2</SP>and thickness is 0.1-0.3 mm. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention is a composite in which a nonwoven fabric layer composed of polyolefin fibers manufactured from a polyolefin resin composition containing inorganic antibacterial fine particles and a nonwoven fabric layer composed of polyolefin fibers not containing inorganic antibacterial fine particles are laminated. The present invention relates to a fiber sheet and a filter using the composite fiber sheet. The composite fiber sheet of the present invention uses a small amount of inorganic antibacterial fine particles per unit area, and despite the fact that the proportion of inorganic antibacterial fine particles used in the entire composite fiber sheet is reduced, In addition to exhibiting anti-virus action stably over a long period of time, it has excellent ability to collect harmful microorganisms and dust, has low pressure loss, has good filter performance, and is also excellent in terms of strength and lightness. Utilizing these superior properties, it is effective for various applications that require high antibacterial and antiviral effects, hygiene, and high filter performance, such as medical supplies, sanitary products, food packaging materials, liquid filters, and gas filters. Can be used for

  In recent years, the development of various antibacterial materials and antibacterial products using such antibacterial materials has been actively developed in response to the growing awareness of sanitary environment, the epidemic of colds and influenza, and the development of new infectious diseases such as avian influenza and coronavirus Has been done. Among antibacterial products, various products using antibacterial fiber sheets have been proposed because they can be manufactured at low cost and are easy to process.

As the organic antibacterial agent, there are known organic antibacterial agents containing phenol, halogen and sulfur, and various other antibacterial agents. Organic antibacterial agents have a halo effect and are excellent in antibacterial properties, but many substances are harmful to the human body, and they are poor in heat resistance and stability compared to inorganic antibacterial agents. When manufacturing fibers, or when fiber products using organic antibacterial agents are used in contact with moisture or oil, they can easily lose their antibacterial effects due to degradation, alteration, dissipation from the product, etc. Generation and deterioration of fiber properties.
From this point of view, the fact is that organic antibacterial agents are not so often used in the production of fibers and fiber products with heating.

  On the other hand, it has been known for a long time that ions of specific metals such as silver, copper, tin, and zinc have an antibacterial action, and these metal ions are exchanged into various inorganic carriers such as zeolite, silica gel, and hydroxyapatite. Inorganic antibacterial agents carried by the adsorption action and the like, and various inorganic antibacterial agents composed of inorganic compounds containing the metal ions have been developed. Inorganic antibacterial agents are safer than organic antibacterial agents, and are less susceptible to volatilization and decomposition, and therefore have superior antibacterial effects and heat resistance. From this point, a nonwoven fabric in which an inorganic antibacterial agent is adhered to a fiber surface such as a polyolefin fiber with a binder (see Patent Document 1), a nonwoven fabric formed from a polyolefin fiber containing an inorganic antibacterial agent, and the like are known. (See Patent Documents 2 and 3).

However, the method of attaching an inorganic antibacterial agent to a nonwoven fabric with a binder is disadvantageous in production because the inorganic antibacterial agent is mixed with the binder and the inorganic antibacterial agent is attached to the nonwoven fabric by post-processing, which increases the number of processing steps. In addition, the inorganic antibacterial agent easily falls off or peels off during use, and there is a problem in the durability of the antibacterial effect. In particular, in a filter made of a nonwoven fabric made of polyolefin fiber, it is possible to improve the adsorptive capacity of filtered matter by applying electret processing, but a polyolefin nonwoven fabric to which an inorganic antibacterial agent is attached by post-processing using a binder There is a problem that the binder component inhibits the electret effect and sufficient filtration performance cannot be obtained.
Also, in the conventional nonwoven fabric formed from polyolefin fibers containing inorganic antibacterial agent, the inorganic antibacterial agent is contained in the fiber and is not exposed on the fiber surface or the degree of exposure is low The antibacterial action of inorganic antibacterial agents cannot be fully exhibited. Moreover, the conventional nonwoven fabric formed from polyolefin fibers containing an inorganic antibacterial agent has a considerably large fiber diameter of the polyolefin fibers forming the nonwoven fabric, and accordingly the specific surface area of the nonwoven fabric is not so high. When used as an antibacterial barrier material, such as an antibacterial filter for filtering pathogens such as underwater dust, pollen, and other pathogens such as viruses, bacteria, and sputum, it is difficult to exert its effects sufficiently.

  Under the circumstances as described above, the present inventors have repeatedly studied for the purpose of providing an antibacterial fiber sheet made of polyolefin fiber that has a high antibacterial action and is excellent in durability of the antibacterial effect. Antibacterial and antiviral effects that the inorganic antibacterial fine particles kneaded in the polyolefin resin are exposed on the surface of the polyolefin fiber, thereby effectively exhibiting the high antibacterial action inherent in the inorganic antibacterial fine particles. Has succeeded in developing an antibacterial fiber sheet made of polyolefin fiber that is excellent in antibacterial and antiviral effects and has developed an antibacterial fiber sheet made of polyolefin fiber and a mask film using the same. Applied (see Patent Documents 4 and 5).

Japanese Patent Laid-Open No. 5-057002 JP-A-5-153874 JP-A-8-325915 JP 2008-88609 A JP 2008-86626 A

“Industrial and Engineering Chemistry”, 1956, Vol. 48, no. No. 8, p. 1342-1346

  The object of the present invention is a non-woven sheet having excellent antibacterial and antiviral effects and durability, low pressure loss, high collection efficiency of harmful microorganisms and dust, excellent film performance, and excellent strength and light weight. Is provided with a smaller amount of inorganic antibacterial agent fine particles than in the past.

Based on the inventions of Patent Documents 4 and 5 described above by the present inventors, the present inventors have further studied. And, in the antibacterial fiber sheet formed from the polyolefin fiber containing the inorganic antibacterial fine particles, the entire fiber sheet is not formed from the polyolefin fiber containing the inorganic antibacterial fine particles, and most of the fiber sheet is inorganic. A polyolefin fiber woven fabric layer with a small fiber diameter containing a large amount of inorganic antibacterial fine particles with a small basis weight and a thin basis weight is formed from a polyolefin fiber nonwoven fabric layer having a small fiber diameter that does not contain fine antibacterial agent fine particles. When a laminated composite fiber sheet is used, the total amount of inorganic antibacterial particles per unit area of the composite fiber sheet as a whole can be greatly reduced compared to conventional ones. Nevertheless, high antibacterial and antiviral effects are achieved. It has been found that it has excellent antibacterial and antiviral effects.
Furthermore, the present inventors have found that the composite fiber sheet has a high filter efficiency because it has a high collection efficiency of foreign matters such as dust and harmful microorganisms and a small pressure loss.
In addition, the present inventors are that the majority of the composite fiber sheet is formed from polyolefin fibers having a small fiber diameter that do not contain inorganic antibacterial fine particles, and the thickness of the portion is small, so that the weight is small. However, the present invention was found to be excellent in strength, and the present invention was completed based on these various findings.

That is, the present invention
(1) << 1 >> The nonwoven fabric layer (A) comprised from the polyolefin fiber (a) manufactured from the polyolefin resin composition containing inorganic antibacterial microparticles, and the polyolefin fiber (b) which does not contain inorganic antibacterial microparticles (b) Is a composite fiber sheet laminated with a non-woven fabric layer (B) composed of
<< 2 >> The nonwoven fabric layer (A) is
<< 2a >> The content of the inorganic antibacterial fine particles in the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is 5 to 20% by mass;
<< 2b >> The average fiber diameter of the polyolefin fibers (a) constituting the nonwoven fabric layer (A) is 0.1 to 3 μm;
<< 2c >> The basis weight is 0.1 to 5 g / m ² ;
<< 2d >> thickness of 0.01 to 0.1 mm; and
<< 2e >> 1 area where 1/100 or more of the volume of the inorganic antibacterial fine particles is exposed on the surface of the polyolefin fiber (a) per 1.0 × 10 ⁻² mm ^{2 of the} nonwoven fabric layer (A) Or at least one portion where the inorganic antibacterial fine particles are exposed on the surface of the polyolefin fiber (a) with an area of 0.01 μm ² or more;
Requirements << 2a >> to << 2e >>
<< 3 >> The nonwoven fabric layer (B) is
<< 3a >> The average fiber diameter of the polyolefin fibers (b) constituting the nonwoven fabric layer (B) is 0.5 to 10 μm;
<< 3b >> The basis weight is 5 to 30 g / m < ² >; and
<3c> 0.1 to 0.3 mm in thickness;
It is a composite fiber sheet characterized by comprising the requirements << 3a >> to << 3c >>.

And this invention,
(2) The composite fiber sheet according to (1), wherein the inorganic antibacterial fine particles contained in the polyolefin fibers (a) constituting the nonwoven fabric layer (A) have an average particle size of 0.01 to 10 μm;
(3) The composite fiber sheet according to (1) or (2) above, wherein the ratio of [weight of nonwoven fabric layer (A)]: [weight of nonwoven fabric layer (B)] is 1: 100 to 1: 5;
(4) The composite fiber sheet according to any one of (1) to (3), wherein the density is 0.05 to 0.12 g / cm ³ ;
It is.

Furthermore, the present invention provides
(5) The polyolefin fiber (a) constituting the nonwoven fabric layer (A) is a mixture of a polyolefin resin (α) containing inorganic antibacterial particles and a polyolefin resin (β) not containing inorganic antibacterial particles. the melt flow rate of a polyolefin resin composition and a polyolefin resin _{(α) (MFR α) (} g / 10 min) and the polyolefin resin (beta) of the melt flow rate (MFR _β) (g / 10 min) The fiber sheet according to any one of the above (1) to (4), which is formed from a polyolefin resin composition that satisfies the following mathematical formula (1).

0 ≦ | MFR _α −MFR _β | ≦ 600 (1)

[However, MFR _α and MFR _β are both measured according to JIS K 7210 under conditions of a temperature of 230 ° C., a load of 2.16 kg, and a measurement time of 10 minutes (unit: g / 10 minutes). It is. ]

And this invention,
(6) The fiber sheet according to any one of (1) to (5), wherein the nonwoven fabric layer (A) and the nonwoven fabric layer (B) are layers made of a nonwoven fabric produced by a melt blow method.
The present invention also provides:
(7) A filter using the fiber sheet according to any one of (1) to (5).

In the composite fiber sheet of the present invention, the inorganic antibacterial fine particles are contained in a high concentration only in the polyolefin fibers (a) having a small basis weight and constituting the thin nonwoven fabric layer (A). Since many fibers are exposed from the surface of the fiber (a), the total amount of the inorganic antibacterial particles per unit area (content) in the entire composite fiber sheet is greatly reduced compared to the conventional case. It has a high antibacterial and antiviral effect, and also has excellent durability of the antibacterial and antiviral effect.
The composite fiber sheet of the present invention is very excellent in filter performance because of high collection efficiency of foreign matters such as dust and harmful microorganisms and low pressure loss.
Furthermore, the composite fiber sheet of the present invention is lightweight because most of the composite fiber sheet is composed of polyolefin fibers having a small fiber diameter that do not contain inorganic antibacterial fine particles, and the thickness of the part is also small. However, it is also excellent in strength.

The present invention is described in detail below.
The composite fiber sheet of the present invention comprises a nonwoven fabric layer (A) composed of a polyolefin fiber (a) made of a polyolefin resin composition containing inorganic antibacterial particles, and a polyolefin fiber (A) containing no inorganic antibacterial particles ( It is a laminated sheet in which at least a nonwoven fabric layer (B) composed of b) is laminated.

The nonwoven fabric layer (A) in the composite fiber sheet of the present invention uses a polyolefin resin composition containing inorganic antibacterial fine particles in a proportion of 5 to 20% by mass based on the total mass of the polyolefin resin composition. It is the layer which consists of a nonwoven fabric comprised from the polyolefin fiber (a) manufactured (namely, the polyolefin fiber which contains inorganic type antimicrobial agent microparticles | fine-particles in the ratio of 5-20 mass%).
The content of the inorganic antibacterial fine particles in the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is preferably 7 to 20% by mass, and more preferably 8 to 15% by mass.
The nonwoven fabric layer (A) is composed of the polyolefin fiber (a) containing the inorganic antibacterial fine particles at a high concentration as described above, whereby the nonwoven fabric layer (A) has a specific small basis weight and a specific weight described below. Combined with the thinness, the inorganic antibacterial fine particles are selectively disposed at a high concentration in the nonwoven fabric layer (A) having a small basis weight and a small thickness, and the inorganic antibacterial fine particles are made of the polyolefin fiber (a). Many are exposed from the surface, and a very high antibacterial effect against pathogens such as bacteria, viruses and sputum is imparted to the composite fiber sheet.
When the content of the inorganic antibacterial fine particles in the polyolefin fiber (a) is less than that prescribed in the present invention, the antibacterial effect of the composite fiber sheet is lowered, while the content of the inorganic antibacterial fine particles is too large. Further, troubles are likely to occur during spinning for producing the nonwoven fabric layer (A), the filter performance is hindered, and the cost is increased.

The average particle diameter of the inorganic antibacterial fine particles contained in the polyolefin fiber (a) constituting the non-woven fabric layer (A) is the yarn breakage during the production of the non-woven fabric layer (A), the dropping of the inorganic antimicrobial fine particles, From the viewpoint of preventing the occurrence of “shot” (polymer balls that do not become fibrous), it is preferably 0.01 to 10 μm, more preferably 0.1 to 8 μm, and 0.3 to 6 μm. Is more preferable. If the average particle size of the inorganic antibacterial fine particles is larger than 10 μm, thread breakage, dropping of the inorganic antibacterial fine particles from the fibers, generation of shots and the like are likely to occur when a fiber sheet or a composite fiber sheet is produced. On the other hand, when the average particle diameter of the inorganic antibacterial fine particles is smaller than 0.01 μm, aggregation between the inorganic antibacterial fine particles occurs, and it becomes difficult to uniformly mix the polyolefin fibers (a).
The average particle diameter of the inorganic antibacterial fine particles in the present specification is an average particle diameter measured using a laser diffraction / scattering particle size distribution measuring device, and a specific measuring method thereof is described in the following examples. It is as follows.

The inorganic antibacterial fine particles used in the present invention are safe for the human body, do not cause volatilization, decomposition, alteration, etc. due to heating during melt spinning of fibers, and the antibacterial and antiviral effects do not decrease in a short period of time. Any of the inorganic antibacterial fine particles can be used. [Hereinafter, antibacterial action (antibacterial effect), antiviral action (antiviral effect), and control action against other harmful microorganisms (control effect)) Effect) ”].
Examples of inorganic antibacterial fine particles that can be used in the present invention include inorganic antibacterial fine particles in which metal ions having antibacterial action such as silver ions, copper ions, zinc ions, tin ions are held in an inorganic carrier, titanium oxide type An inorganic antibacterial agent fine particle etc. can be mentioned, These 1 type (s) or 2 or more types can be used.
In the inorganic antibacterial fine particles in which metal ions having antibacterial properties are held in an inorganic carrier, the type of inorganic carrier is not particularly limited, and any one that does not exhibit a fiber sheet deterioration action, etc. can be used. An inorganic carrier having high capacity and metal ion adsorption capacity and high metal ion retention capacity is preferably used. Examples of such an inorganic carrier include zeolite, zirconium phosphate, calcium phosphate, etc. Among them, zeolite having a high ion exchange ability and zirconium phosphate are particularly preferable.
Among the above-described inorganic antibacterial fine particles, in the present invention, inorganic antibacterial fine particles in which silver ions are held on the above-described inorganic carrier are particularly preferably used.

In the composite fiber sheet of the present invention, the average fiber diameter of the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is 0.1 to 3 μm, preferably 0.5 to 2.5 μm. It is more preferable that it is 7-2.3 micrometers, and it is still more preferable that it is 1.0-2.0 micrometers.
By making the average fiber diameter of the polyolefin fibers (a) constituting the nonwoven fabric layer (A) within the above range, the degree of exposure and exposure from the fiber surface of the inorganic antibacterial fine particles contained in the polyolefin fibers (a) As the number increases, the antibacterial performance of the nonwoven fabric layer (A) and thus the composite fiber sheet is further enhanced, and the flexibility and filter performance are excellent. When the average fiber diameter of the polyolefin fibers (a) constituting the nonwoven fabric layer (A) is smaller than 0.1 μm, the inorganic antibacterial fine particles are hardly retained in the nonwoven fabric layer (A), and the productivity is lowered. Increases costs. On the other hand, when the average fiber diameter of the polyolefin fiber (a) constituting the nonwoven fabric layer (A) exceeds 3 μm, the inorganic antibacterial fine particles contained in the polyolefin fiber (a) are exposed from the surface of the polyolefin fiber (a). A degree falls and it becomes difficult to provide a high antimicrobial effect to a nonwoven fabric layer (A).
In addition, the average fiber diameter of the polyolefin fiber (a) constituting the nonwoven fabric layer (A) and the polyolefin fiber (b) constituting the nonwoven fabric layer (B) in the present specification is the nonwoven fabric layer (A) or the nonwoven fabric layer (B ) Is an average value obtained from a fiber diameter measured from a photograph taken with a scanning electron microscope (SEM), and details thereof are as described in the following examples.

In the composite fiber sheet of the present invention, the ratio of the average particle diameter of the inorganic antibacterial fine particles contained in the polyolefin fiber (a) constituting the nonwoven fabric layer (A) to the average fiber diameter of the polyolefin fiber (a) is 1:10. It is preferably ˜6: 1, more preferably 1: 2 to 2: 1.
By setting the ratio of the average particle diameter of the inorganic antibacterial agent fine particles and the average fiber diameter of the polyolefin fiber (a) within the above range, the spinnability when producing the nonwoven fabric layer (A) is improved, and the polyolefin fiber ( It is possible to satisfactorily expose the inorganic antibacterial fine particles from the surface of a) and to prevent the inorganic antibacterial fine particles from dropping from the nonwoven fabric layer (A).

In composite fiber sheet of the present invention, the basis weight of the nonwoven fabric layer (A) is a 0.1 to 5 / m ^2, is preferably 0.5~3g / m ^2, 0.8~2g / m ² is more preferable.
When the basis weight of the nonwoven fabric layer (A) is the above-described small value, the inorganic antibacterial fine particles are selectively (locally) arranged in the nonwoven fabric layer (A), and in the polyolefin fiber (a) Despite containing a high concentration of inorganic antibacterial particles, the total amount of the polyolefin fiber (a) in the composite fiber sheet and hence the amount of inorganic antibacterial particles can be reduced. It is possible to impart a high antibacterial effect and excellent durability to the fiber sheet while significantly reducing the amount of agent fine particles used than before.
In the composite fiber sheet of the present invention, the basis weight of the nonwoven fabric layer (A) made of the polyolefin fiber (a) containing inorganic antibacterial fine particles is the above-described small value, and the nonwoven fabric occupies the entire composite fiber sheet Since the mass ratio of the layer (A) is small, weight reduction of the composite fiber sheet is achieved and the strength of the composite fiber sheet is maintained high.
If the basis weight of the nonwoven fabric layer (A) is smaller than that defined in the present invention, the content of the inorganic antibacterial fine particles in the nonwoven fabric layer (A) is too small to provide sufficient antibacterial action to the fiber sheet, Moreover, the fiber surface area collecting effect is reduced and the filter performance is reduced. On the other hand, if the basis weight of the nonwoven fabric layer (A) is too large, the airflow resistance becomes high and the filter performance is lowered, the strength is lowered, the lightness is lowered, and the productivity is easily lowered.

In the composite fiber sheet of the present invention, the thickness of the nonwoven fabric layer (A) is 0.01 to 0.1 mm, preferably 0.015 to 0.08 mm, and preferably 0.018 to 0.06 mm. More preferred.
When the thickness of the nonwoven fabric layer (A) is smaller than the range defined in the present invention, the nonwoven fabric layer (A) has a basis weight of 0.1 to 5 g / m ² as described above. The air permeability and liquid permeability of (A) are lowered, the filter performance of the composite fiber sheet is lowered, and it becomes hard and the texture is impaired. On the other hand, when the thickness of the nonwoven fabric layer (A) is larger than the range specified in the present invention, the nonwoven fabric layer (A) has a basis weight of 0.1 to 5 g / m ² as described above. The density of A) becomes low, and the gaps between the fibers become large, causing harmful microorganisms and dust to pass through, reducing the filter performance, generating fluff, and lowering the workability.

In the nonwoven fabric layer (A) constituting the composite fiber sheet of the present invention, the inorganic antibacterial fine particles kneaded into the polyolefin resin composition constituting the polyolefin fiber (a) by melt-kneading or the like are polyolefin fibers (a). Per unit area of 1.0 × 10 ⁻² mm ^{2 of} the non-woven fabric layer (A), which is not completely buried inside but exposed on the surface of the polyolefin fiber (a).
-1/100 or more of the volume of the inorganic antibacterial fine particles has a portion exposed on the surface of the polyolefin fiber (a) at a ratio of 1 or more; or
The inorganic antibacterial fine particles have an area of 0.01 μm ² or more and a portion exposed on the surface of the polyolefin fiber (a) at a ratio of 1 or more.
In the composite fiber sheet of the present invention, the inorganic antibacterial fine particles contained in the polyolefin fiber (a) constituting the nonwoven fabric layer (A) are not completely embedded in the polyolefin fiber (a), and are not on the outside of the fiber. By exposing a large number, the antibacterial action of the inorganic antibacterial fine particles themselves is sufficiently exerted, so that a high antibacterial effect is imparted to the non-woven fabric layer (A) and thus to the composite fiber sheet.
The number of locations where 1/100 or more of the volume of the inorganic antibacterial fine particles per 1 area of the nonwoven fabric layer (A) 1.0 × 10 ⁻² mm ² is exposed on the surface of the polyolefin fiber (a) is 1 If the amount of the inorganic antibacterial agent fine particles is less than 1 in an area of 0.01 μm ² or more and exposed to the surface of the polyolefin fiber (a), the nonwoven fabric layer (A) has an antibacterial property. The performance, and thus the antibacterial performance of the composite fiber sheet, is reduced.

In the nonwoven fabric layer (A) constituting the composite fiber sheet of the present invention, 1/100 or more of the volume of the inorganic antibacterial fine particles is polyolefin fiber per 1.0 × 10 ⁻² mm ² area of the nonwoven fabric layer (A). The area exposed to the surface of (a) is 1.5 or more, more preferably 2 or more, particularly 2.5 or more, or the area of the inorganic antibacterial fine particles is 0.01 μm ² or more. It is preferable to have 1.5 or more, more preferably 2 or more, particularly 2.5 or more, portions exposed on the surface of the polyolefin fiber (a).
In the present specification, “inorganic antibacterial agent fine particles are exposed on the surface of the polyolefin fiber” includes a case where the inorganic antibacterial agent fine particles are exposed to protrude outside from the surface of the polyolefin fiber.

In the nonwoven fabric layer (A) constituting the composite fiber sheet of the present invention, the portion where 1/100 or more of the volume of the inorganic antibacterial agent fine particles is exposed on the surface of the polyolefin fiber (a) is the nonwoven fabric layer (A). As long as the number of exposed areas of the inorganic antibacterial microparticles is less than 0.01 μm ² as long as the area is 1 or more per 1.0 × 10 ⁻² mm ^2. I do not care.
Whether or not the inorganic antibacterial fine particles are exposed from the surface of the polyolefin fiber (a) is a photograph of the nonwoven fabric layer (A) taken with a scanning electron microscope (SEM) from the surface side of the nonwoven fabric layer (A). (It can be discriminated from the “SEM photograph”. The inorganic fine particle portion exposed from the surface of the polyolefin fiber (a) is lighter than the fiber portion made of the polyolefin resin, and the polyolefin fiber (a ) Can be clearly distinguished.

In the nonwoven fabric layer (A), by measuring the size and number of light-colored portions where the inorganic antibacterial agent fine particles are exposed in the SEM photograph obtained by photographing the surface of the nonwoven fabric layer (A), the area of the nonwoven fabric layer (A) 1. The number of locations where 1/100 or more of the volume of the inorganic antibacterial fine particles per 0 × 10 ⁻² mm ² is exposed on the surface of the polyolefin fiber (a) can be examined.
Specifically, when the inorganic antibacterial agent fine particles are spherical or nearly spherical, the inorganic antibacterial fine particle part exposed from the surface of the polyolefin fiber (a) always has a predetermined diameter in the SEM photograph. Is taken as a circle with or near the circle (the cross section of the sphere is circular no matter where it takes), and the diameter of the circle is measured and compared with the average particle size of the inorganic antibacterial fine particles that form a sphere It is possible to determine whether 1/100 or more of the volume of the inorganic antibacterial fine particles is exposed from the surface of the polyolefin fiber (a).
For example, in a photograph taken with a scanning electron microscope (SEM), the diameter of the circle corresponding to the portion where the spherical inorganic antibacterial fine particles are exposed from the surface of the polyolefin fiber (a) is If it is the same as the average particle size, 1/2 or more of the volume of the inorganic antibacterial agent fine particles is exposed from the surface of the polyolefin fiber (a). Further, if the diameter of the photographed circle corresponding to the exposed portion of the inorganic antibacterial fine particles is 1/20 or more of the average particle diameter of the inorganic antibacterial fine particles, 1/100 or more of the volume of the inorganic antibacterial fine particles Is exposed from the surface of the polyolefin fiber (a).

  On the other hand, when the shape of the inorganic antibacterial fine particles contained in the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is not spherical or nearly spherical, the surface of the polyolefin fiber (a) in the SEM photograph The shape of the fine part of the inorganic antibacterial agent exposed from is not necessarily a circular shape or a shape close thereto. Moreover, even if the photographed shape of the inorganic antibacterial fine particle portion exposed from the surface of the polyolefin fiber (a) happens to be a circular shape or a shape close thereto, the volume of the exposed portion of the inorganic antibacterial fine particle portion It may not be 1/100 or more. In such a case, whether or not 1/100 or more of the volume of the inorganic antimicrobial fine particles is exposed from the surface of the polyolefin fiber (a) based on the size of the exposed portion of the inorganic antimicrobial fine particles in the SEM photograph. Is likely to be difficult to determine. Therefore, when the inorganic antibacterial agent fine particles are not spherical or not nearly spherical, the degree of exposure is not determined by the volume ratio of the exposed part, but by the area of the exposed part of the inorganic antibacterial fine particle based on the SEM photograph. Determine.

In the present invention, in the SEM photograph of the surface of the nonwoven fabric layer (A), the portion where the inorganic antibacterial agent fine particles are exposed on the surface of the polyolefin fiber (a) with an area of 0.01 μm ² or more is the nonwoven fabric layer (A even when the area of 1.0 × 10 exists ^-2 mm ² per one or more places), non-woven layer (a), a high antimicrobial properties are imparted to the composite fiber sheet thus the present invention.
In the nonwoven fabric layer (A), “the location where the inorganic antibacterial fine particles are exposed to the surface of the polyolefin fiber (a) with an area of 0.01 μm ² or more is the area of the nonwoven fabric layer (A) 1.0 × 10 ^As long as the requirement “at least one location per ⁻² mm ² ” is satisfied, the volume of the inorganic antibacterial fine particles exposed from the surface of the polyolefin fiber (a) is 1/100 of the volume of the inorganic antibacterial fine particles. It may be less.

When the inorganic antibacterial fine particles to be contained in the polyolefin fiber (a) are spherical or nearly spherical, the number of exposed portions of the inorganic antibacterial fine particles in the non-woven fabric layer (A) is measured by the “inorganic It may be performed by counting “locations where 1/100 or more of the volume of the antibacterial agent fine particles is exposed on the surface of the polyolefin fiber (a)” or “the area where the inorganic antibacterial fine particle is 0.01 μm ² or more”. And may be carried out by counting the “locations exposed on the surface of the polyolefin fiber (a)”.

  The photograph of the surface of the nonwoven fabric layer (A) taken with a scanning electron microscope (SEM) shows the polyolefin fiber (a) located on the outermost surface of the nonwoven fabric layer (A) and the polyolefin located on the back (inside) Although the fiber (a) is also shown, since it is often difficult to distinguish the polyolefin fiber (a) located on the outermost surface and the polyolefin fiber (a) located on the inner side from the photograph, in the present invention, the polyolefin fiber (a In the measurement of the size and number of fine particles of the inorganic antibacterial agent exposed from the surface of (), is it the polyolefin fiber (a) located on the outermost surface, the inner side or the polyolefin fiber (a)? The inorganic anti-resistant exposed from the surface of the polyolefin fiber (a) for all the polyolefin fibers (a) in the SEM photograph Agent the size and number of fine particles therefrom shall be measured, therefore the provision of the exposed portion of the inorganic antimicrobial agent particles in the non-woven fabric layer (A) refers to a value measured in this way.

Polyolefin resins for producing the polyolefin fibers (a) constituting the nonwoven fabric layer (A) include polypropylene, polyethylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene / propylene copolymer, ethylene -Polyolefin resins such as 1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, propylene / 1-brene copolymer, 4-methyl-1-pentene / 1-decene copolymer 1 type, or 2 or more types of these can be used. Among them, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, particularly polypropylene, has good processability when producing the nonwoven fabric layer (A) by the melt blow method, and is easily electretized. It is preferably used because of its low cost.
When a non-woven fabric layer (A) (non-woven fabric) is produced by a melt blowing method using a resin composition containing inorganic antimicrobial fine particles, the inorganic antimicrobial fine particles are contained in the polymer, so that "shot" When the fiber sheet having the nonwoven fabric layer with frequent shots is used as a filter, “leakage” occurs, but when the nonwoven fabric layer (A) is produced using polypropylene, Such a shot can be prevented from occurring.

  Moreover, as polyolefin resin for manufacturing the polyolefin fiber (a) which comprises the nonwoven fabric layer (A) in the composite fiber sheet of this invention, based on JISK7210, temperature 230 degreeC, load 2.16kg, and measurement Those having a melt flow rate (MFR) of 5 to 2500 g / 10 minutes, particularly 40 to 1600 g / 10 minutes, measured under conditions of 10 minutes of time are preferably used. By using the polyolefin resin having an MFR in the above range, the fiberization at the time of producing the nonwoven fabric layer (A) is smoothly and uniformly performed, the fiber diameter is thin, and the formation is uniform. In addition, when the polyolefin fiber (a) which comprises a nonwoven fabric layer (A) is manufactured from the mixture of 2 or more types of polyolefin resin, above-mentioned MFR is MFR of the mixture of 2 or more types of polyolefin resin. Say.

In the production of the nonwoven fabric layer (A), a polyolefin resin composition is prepared by mixing inorganic antibacterial fine particles at once in a polyolefin resin, and a nonwoven fabric layer (A) (nonwoven fabric) is produced using the polyolefin resin composition. However, in order to smoothly obtain the nonwoven fabric layer (A) having a high antibacterial action by exposing a large number of inorganic antibacterial fine particles on the surface of the polyolefin fiber (a) constituting the nonwoven fabric layer (A). It is preferable to prepare an inorganic antibacterial fine particle-containing polyolefin resin composition for producing the nonwoven fabric layer (A) as follows.
That is, the polyolefin resin (α) and the polyolefin resin (β) satisfying the following mathematical formula (1) with the absolute value of the difference in melt flow rate are used, and the inorganic antibacterial agent fine particles are made of the polyolefin resin (α). A polyolefin resin (α) composition is prepared by mixing under melting, and the composition is mixed with a polyolefin resin (β) that does not contain inorganic antibacterial fine particles and a polyolefin containing inorganic antibacterial fine particles. It is preferable to produce the nonwoven fabric layer (A) using the polyolefin resin composition after the production of the resin resin composition.

0 ≦ | MFR _α −MFR _β | ≦ 600 (1)

[In the above formula, MFR _α is the melt flow rate of the polyolefin-based resin (α), MFR _β is the melt flow rate of the polyolefin-based resin (β), and both melt flow rates are in accordance with JIS K 7210 at a temperature of 230 It is a melt flow rate (unit: g / 10 minutes) when measured under the conditions of ° C., a load of 2.16 kg, and a measurement time of 10 minutes. ]

Nonwoven fabric layer (A) using a polyolefin resin composition containing inorganic antibacterial fine particles prepared by the method described above using a polyolefin resin (α) and a polyolefin resin (β) that satisfy the above mathematical formula (1) ( in producing a nonwoven fabric), the absolute value of the difference between MFR _beta of MFR _alpha and a polyolefin resin of the polyolefin resin (alpha) (beta) is more preferably 400 or less, it is 0 to 300 Further preferred.

  A polyolefin resin (α) and a polyolefin resin (β) are used, inorganic antibacterial fine particles are premixed in the polyolefin resin (α), and the polyolefin resin (β) is mixed with the inorganic antibacterial agent. In preparing a nonwoven fabric layer (A) using a polyolefin resin composition containing fine particles and using the polyolefin resin composition, polyolefin resin (α) (before containing inorganic antibacterial agent fine particles) Resin): The polyolefin resin (β) is used in a mass ratio of preferably 99: 1 to 1:99, more preferably 80:20 to 3:97.

  In preparing a polyolefin resin composition containing inorganic antibacterial fine particles by the above-described method using a polyolefin resin (α) and a polyolefin resin (β), extrusion is performed using a twin screw extruder or the like. However, the polyolefin resin (α) may be mixed with the inorganic antibacterial fine particles and then mixed with the polyolefin resin (β), or may be extruded after chip blending using a masterbatch. In the case of the masterbatch method, for example, a masterbatch in which inorganic antibacterial fine particles are kneaded into a polyolefin resin (α) such as polypropylene is prepared, and this is mixed with a polyolefin resin (β) such as polypropylene to be inorganic. By preparing a polyolefin resin composition containing fine antibacterial agent fine particles, dispersion of the inorganic antibacterial fine particles in the polyolefin resin is improved, and the inorganic antibacterial fine particles are exposed on the surface of the polyolefin fiber (a). It becomes easy to do.

  As an apparatus for mixing the inorganic antibacterial fine particles into the polyolefin resin, any apparatus that can uniformly mix the inorganic antibacterial fine particles into the polyolefin resin can be used, such as a twin screw extruder. It is preferable to use a kneading apparatus from the viewpoint that the inorganic antibacterial fine particles can be uniformly mixed in the polyolefin resin with high productivity.

  The polyolefin resin composition containing the inorganic antibacterial fine particles that form the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is a range that does not impair the effects of the present invention, and other polymers or An additive may be contained. Examples of the additives include weathering stabilizers such as antioxidants, radical absorbers and ultraviolet absorbers, surfactants, pigments and the like.

  The type of nonwoven fabric constituting the nonwoven fabric layer (A) and the method for producing the nonwoven fabric layer (A) are not particularly limited, and any layer may be used as long as it is a nonwoven fabric layer having the above-described characteristics. Among them, the nonwoven fabric layer (A) is obtained by a melt blow method. It is highly preferred to manufacture. By manufacturing the nonwoven fabric layer (A) by adopting the melt blow method, it is composed of polyolefin fibers (a) having an average fiber diameter defined in the present invention, and has a basis weight and thickness defined in the present invention, and is inorganic. It is possible to smoothly produce a nonwoven fabric layer (A) having a high antibacterial action in which a large amount of the antimicrobial agent-based fine particles are exposed from the surface of the polyolefin fiber (a) constituting the nonwoven fabric layer (A).

Many methods have been proposed for producing a fiber sheet (nonwoven fabric) by the melt blow method since Non-Patent Document 1 discloses a basic apparatus and method for the melt blow method. In producing the non-woven fabric layer (A) in the composite fiber sheet of the present invention by the melt blow method, the method described in Non-Patent Document 1 or other conventionally known melt blow methods can be employed.
For example, after a polyolefin resin composition containing inorganic antibacterial fine particles is supplied to a melt blown nonwoven fabric manufacturing apparatus and melted at 160 to 340 ° C. with an extruder (extruder), a plurality of spinning holes are aligned. At the same time as discharging from the arrayed die at a temperature of 200 to 320 ° C., the heated air of 200 to 330 ° C. is ejected from a slit provided in the vicinity of the spinning hole, and the discharged fibers are made fine, and the net conveyor is located below. A nonwoven fabric layer (A) can be manufactured by collecting on top.

The nonwoven fabric layer (B) in the composite fiber sheet of this invention is comprised from the polyolefin fiber (b) of the average fiber diameter of 0.5-10 micrometers which does not contain inorganic type antibacterial agent microparticles | fine-particles.
The average fiber diameter of the polyolefin fiber (b) constituting the nonwoven fabric layer (B) is preferably 1 to 8 μm, more preferably 2 to 5 μm, and further preferably 2.5 to 4.5 μm. preferable.
When the average fiber diameter of the polyolefin fiber (b) constituting the nonwoven fabric layer (B) is in the above range, the air flow resistance of the composite fiber sheet of the present invention becomes an appropriate value, or harmful microorganisms such as viruses and bacteria, Dust and other trapping efficiency is increased and the filter performance is excellent. When the average fiber diameter of the polyolefin fiber (b) is smaller than the above, the ventilation resistance increases, which is not suitable for use as a filter or the like. On the other hand, when the average fiber diameter of the polyolefin fiber (b) is larger than the above, The gap size in B) becomes large, and the collection performance of harmful substances such as harmful microorganisms and dust is lowered.

  In the composite fiber sheet of the present invention, the average fiber diameter of the polyolefin fibers (b) constituting the nonwoven fabric layer (B) is preferably larger than the average fiber diameter of the polyolefin fibers (a) constituting the nonwoven fabric layer (A). In general, the average fiber diameter of the polyolefin fiber (b) is 1 to 20 times, more preferably 1.5 to 10 times, particularly 2 to 5 times the average fiber diameter of the polyolefin fiber (a). preferable. As a result, strength, durability, and fiber diameter gradient in the thickness direction of the composite fiber sheet are imparted to the composite fiber sheet, and the filter performance (collection efficiency, pressure loss, life, etc.) of the composite fiber sheet is improved.

Basis weight of the nonwoven fabric layer in the composite fiber sheet of the present invention (B) is 5 to 30 g / m ^2, is preferably 10 to 25 g / m ^2, and more preferably 13~22g / m ^2. When the basis weight of the nonwoven fabric layer (B) is within the above range, strength and durability are imparted to the composite fiber sheet, and the filter performance (collection efficiency, pressure loss, life, etc.) of the composite fiber sheet is improved. .

  The thickness of the nonwoven fabric layer (B) in the composite fiber sheet of the present invention is 0.1 to 0.3 mm, preferably 0.12 to 0.28 mm, and more preferably 0.15 to 0.25 mm. preferable. When the thickness of the nonwoven fabric layer (B) is within the above range, the strength, durability, handleability, and filter performance (collection efficiency, pressure loss, etc.) of the composite fiber sheet are improved.

  Polyolefin resins for producing the polyolefin fibers (b) constituting the nonwoven fabric layer (B) include polypropylene, polyethylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene / propylene copolymer, ethylene -Polyolefin resins such as 1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, propylene / 1-brene copolymer, 4-methyl-1-pentene / 1-decene copolymer 1 type, or 2 or more types of these can be used. Among them, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, particularly polypropylene, has good processability when producing the nonwoven fabric layer (B), is easily electretized, and is low in cost. It is preferably used because of its existence.

  The polyolefin-based resin forming the polyolefin fiber (b) constituting the nonwoven fabric layer (B) may contain other polymers and additives as necessary within a range not impairing the effects of the present invention. Examples of the additives include weathering stabilizers such as antioxidants, radical absorbers and ultraviolet absorbers, surfactants, pigments and the like.

The type of nonwoven fabric forming the nonwoven fabric layer (B) and the production method thereof are not particularly limited, and any nonwoven fabric can be used as long as it is produced from a polyolefin that does not contain inorganic antibacterial fine particles and has the above-described characteristics defined in the present invention. But you can. Examples of the nonwoven fabric that forms the nonwoven fabric layer (B) include melt blown nonwoven fabrics, entangled nonwoven fabrics entangled by needle punching or water entanglement, and thermal bond nonwoven fabrics composed of polyolefin fibers that do not contain inorganic antibacterial fine particles. , Spunbond nonwoven fabrics, film split yarn nonwoven fabrics, and the like.
Among these, it is very preferable that the nonwoven fabric layer (B) is made of a nonwoven fabric produced by a melt blow method. By manufacturing the nonwoven fabric layer (B) by employing the melt blow method, the nonwoven fabric layer (b) is composed of polyolefin fibers (b) having an average fiber diameter defined in the present invention and having a basis weight and thickness defined in the present invention ( B) can be manufactured smoothly.

In producing the non-woven fabric layer (B) by the melt blow method, the method described in Non-Patent Document 1 or other conventionally known melt blow methods can be employed.
For example, as in the case of the nonwoven fabric layer (A), a polyolefin resin that does not contain inorganic antibacterial fine particles is supplied to a melt blown nonwoven fabric production apparatus and melted at 160 to 340 ° C. with its extruder (extruder). After that, a plurality of spinning holes are discharged from a die arranged in a row at a temperature of 200 to 320 ° C., and at the same time, 200 to 330 ° C. of heated air is ejected from a slit provided in the vicinity of the spinning holes, and the discharged fibers are made finer. A nonwoven fabric layer (B) can be manufactured by collecting it on the net conveyor etc. which are located below.

In the production of the composite fiber sheet of the present invention, after the nonwoven fabric layer (B) is produced by the melt blow method described above, the inorganic antibacterial agent fine particles are placed on the nonwoven fabric layer (B) while being continuously transferred. A method (direct melt blow method) of forming the nonwoven fabric layer (A) by melt-blowing the contained polyolefin-based resin composition to form a fine fiber and depositing and laminating it into a thin layer is particularly preferred.
In the case of this method, the bonding step between the nonwoven fabric layer (A) and the nonwoven fabric layer (B) is not required, and the composite fiber sheet in which the nonwoven fabric layer (A) is firmly bonded on the nonwoven fabric layer (B) is continuously formed. Can be manufactured with good productivity.

In the composite fiber sheet of the present invention, the ratio of [weight of nonwoven fabric layer (A)]: [weight of nonwoven fabric layer (B)] is 1: 5 to 1: 100 [weight of nonwoven fabric layer (B) is nonwoven fabric layer (A). 5 to 100 times the basis weight)], more preferably in the range of 1: 7 to 1:80, and still more preferably in the range of 1:10 to 1:50.
In the composite fiber sheet of the present invention, the ratio of [thickness of nonwoven fabric layer (A)]: [thickness of nonwoven fabric layer (B)] is 1: 3 to 1:30 [thickness of nonwoven fabric layer (B) is nonwoven fabric. It is preferably 3 to 30 times the thickness of the layer (A)], more preferably 1: 5 to 1:25, and even more preferably 1:10 to 1:20.
The ratio of [weight of nonwoven fabric layer (A)]: [weight of nonwoven fabric layer (B)] and / or [thickness of nonwoven fabric layer (A)]: [thickness of nonwoven fabric layer (B)] is in the above range. When there is a thin non-woven fabric layer (A) composed of polyolefin fibers (a) containing inorganic antibacterial fine particles, a high disinfecting effect is imparted to the composite fiber sheet, while the nonwoven fabric layer ( A layer having high filter performance is formed in the non-woven fabric layer (B) which is thicker and has a larger basis weight than A), and the collection of harmful microorganisms, dust, etc., ventilation, liquid passage, etc. are made well, and the composite fiber sheet Strength and durability are imparted.

  The composite fiber sheet of the present invention has a total thickness [total thickness of the non-woven fabric layer (A) and the non-woven fabric layer (B)] of 0.08 to 0 in terms of handling properties, light weight, strength, and the like of the composite fiber sheet. .35 mm is preferable, 0.10 to 0.30 mm is more preferable, and 0.12 to 0.28 mm is still more preferable.

In the composite fiber sheet of the present invention, the density of the nonwoven fabric layer (A) is 0.03 to 0.2 g / cm ³ , particularly 0.05 to 0.1 g / cm ³ , and the density of the nonwoven fabric layer (B) is 0.00. 03 to 0.2 g / cm ³ , particularly 0.05 to 0.1 g / cm ³ , and the density of the entire composite fiber sheet is 0.03 to 0.2 g / cm ³ , particularly 0.05 to 0.1 g / cm ³ . Cm ³ is preferable from the viewpoint of the breathability and liquid permeability of the composite fiber sheet, collection performance of harmful microorganisms and dust, strength, durability, and lightness.

  In the composite fiber sheet of the present invention, the nonwoven fabric layer (A) and the nonwoven fabric layer (B) may be bonded with such strength that the processability of the composite fiber sheet is good and the filter performance of the composite fiber sheet does not deteriorate. is necessary. If the delamination strength between the nonwoven fabric layer (A) and the nonwoven fabric layer (B) is too small, troubles such as separation of the nonwoven fabric layer (A) and the nonwoven fabric layer (B) occur when the composite fiber sheet is used for each application. On the other hand, when the delamination strength between the non-woven fabric layer (A) and the non-woven fabric layer (B) is too large, the densification occurs at the adhesive interface between the non-woven fabric layer (A) and the non-woven fabric layer (B), and the filter performance Reduction may occur.

Composite fiber sheet of the present invention preferably has air permeability according to Frazier method in entire composite fiber sheet is 40~120cc / cm ² / sec, more preferably 50~100cc / cm ² / sec, 60 More preferably, it is -90cc / cm < ² > / sec. When the air permeability of the composite fiber sheet is in the above-described range, the air resistance and the collection performance are balanced, and the filter performance is improved.

The composite fiber sheet of the present invention can be used by being laminated with other materials as necessary. The type of the other material to be laminated is not particularly limited, and any material can be used as long as it can be laminated with the composite fiber sheet of the present invention. However, a sheet-like or film-like material can be easily laminated with the composite fiber sheet. In addition, it is preferably used because it is easy to handle and process a laminate obtained by laminating the other material on the composite fiber sheet.
Specific examples of other materials that can be laminated with the composite fiber sheet of the present invention include nonwoven fabrics, woven fabrics, knitted fabrics, films, and papers.
Among these, when the other material is a nonwoven fabric, a long-fiber nonwoven fabric such as a spunbond nonwoven fabric, a melt blown nonwoven fabric, and a flash spun nonwoven fabric, a spunlace nonwoven fabric, an airlaid nonwoven fabric, a thermal bond nonwoven fabric, a needle punched nonwoven fabric, a chemical bond nonwoven fabric, Paper can be mentioned. The raw material of the fibers forming these nonwoven fabrics is not particularly limited, and examples thereof include polyolefins such as polyethylene, polypropylene and ethylene-modified polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, or these Examples include copolymers, polyvinyl chloride, acrylic polymers, polystyrene, polysulfone, polytrifluorochloroethylene, polycarbonate, polyurethane, rayon, vinylon, and pulp.
Moreover, when using a nonwoven fabric as another material and laminating | stacking with the composite fiber sheet of this invention, the said nonwoven fabric may be composite fibers, such as a core-sheath type structure or a side-by-side type structure, and two types of nonwoven fabrics. It may be formed using the above fibers.
When other materials are laminated on the composite fiber sheet of the present invention, excellent properties (particularly good antibacterial performance, filter performance, etc.) possessed by the composite fiber sheet of the present invention are obtained by laminating the other materials. It is necessary to select other materials to be laminated and the lamination method so that the above is not impaired.

The use of the composite fiber sheet of the present invention is not particularly limited, and can be used for various filters (filter media) such as air filters and liquid filters, medical supplies, hygiene products, food packaging materials, wipers, and the like.
When the composite fiber sheet of the present invention is used as a filter, electret processing may be applied to improve the filter medium performance. In the composite fiber sheet of the present invention, since both the nonwoven fabric layer (A) and the nonwoven fabric layer (B) are composed of polyolefin fibers, they are easily charged by electret processing, particularly the nonwoven fabric layer (A) and the nonwoven fabric layer (B). Is made of polypropylene fiber, it is industrially easily electretized and the charging effect is stably maintained for a long time.
The electretization may be performed by electretizing each of the nonwoven fabric layer (A) and the nonwoven fabric layer (B) individually, and then laminating them to form a composite fiber sheet, and the composite fiber sheet may be further electretized. The electret treatment may be performed only after the nonwoven fabric layer (A) is laminated on (B) to produce a composite fiber sheet.
The electret processing method in carrying out the electret process of the composite fiber sheet of this invention is not restrict | limited, It can carry out according to a well-known method. For example, the non-woven fabric layer (B) or the composite fiber sheet is in contact with the ground electrode between the flat or roll-shaped ground electrode and the needle-shaped or wire-shaped electrode placed 1-10 cm above the ground electrode. Electret machining can be performed by applying a high-voltage direct current (for example, a direct current having a voltage of 10 to 70 KV) while being arranged or passed.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.
Moreover, each physical property value in the following examples, comparative examples and reference examples was measured or evaluated by the following methods.

(1) Polyolefin melt flow rate (MFR):
The following Examples, Comparative Examples and Reference Examples under the conditions of a temperature of 230 ° C., a load of 2.16 kg and a measurement time of 10 minutes according to JIS K 7210 using an MFR measuring device (“L244” manufactured by Takara Kogyo Co., Ltd.) The melt flow rate (MFR) (g / 10 min) of the polyolefin used in 1 was measured.

(2) Average particle size of inorganic antibacterial agent fine particles:
(I) Water was added to the inorganic antibacterial fine particles (silver inorganic antibacterial fine particles) used in the following Examples, Comparative Examples, and Reference Examples, and the mixture was sufficiently dispersed to be uniformly dispersed in water.
(Ii) Using the dispersion obtained in (i) above, particle size distribution analysis was performed using a laser diffraction / scattering particle size measuring device (“LA-920” manufactured by Horiba, Ltd.).
At the time of measurement, an ultrasonic homogenizer built in the measuring device is used for measurement after irradiating with ultrasonic waves for 1 minute, and the arithmetic average value (μm) calculated by the volume-based particle size distribution is calculated for the inorganic antibacterial fine particles. The average particle size was taken.

(3) Average fiber diameter of polyolefin fibers constituting the nonwoven fabric layer (A) and the nonwoven fabric layer (B):
A test piece (length × width = 5 cm × 5 cm) was taken from the non-woven fabric layer (A) and the non-woven fabric layer (B), and the central portion (portion centered at the intersection of diagonal lines) on the surface of the test piece was scanned with an electron microscope. (SEM) was used to take a photograph at a magnification of 1000 times. A circle with a radius of 15 cm is drawn on the center of the photograph (intersection of diagonal lines), and all unfused polyolefin fibers (usually about 50 to 100 fibers) contained in the circle are drawn. The fiber diameter at the central part in the length direction or a position close to it was measured with calipers, and the average value was taken as the average fiber diameter (μm) of the polyolefin fiber.
In measuring the average fiber diameter of the polyolefin fiber, the polyolefin fiber photographed in the photograph is a polyolefin fiber located on the outermost surface of the nonwoven fabric layer (A) or the nonwoven fabric layer (B) or is located on the inner side. The average fiber diameter was determined for all polyolefin fibers in the SEM photograph without distinguishing whether the fibers were fibers.

(4) Fabric weight of nonwoven fabric layer (A), nonwoven fabric layer (B) and composite fiber sheet (fiber sheet):
(I) The basis weight of the nonwoven fabric layer (B):
From the nonwoven fabric used as the nonwoven fabric layer (B) in the following examples, comparative examples and reference examples, a square test piece of length × width = 20 cm × 20 cm was collected and conformed to JIS L1906 (general long fiber nonwoven fabric test method). And the fabric weight was measured in three places along the width direction of a test piece, the average value was computed, and it was set as the fabric weight of the nonwoven fabric layer (B).
(Ii) Weight of composite fiber sheet (fiber sheet):
From the composite fiber sheet (fiber sheet) finally obtained in the following examples, comparative examples and reference examples, a square test piece of length × width = 20 cm × 20 cm was collected, and JIS L1906 (general long fiber nonwoven fabric test) In accordance with (Method), the basis weight was measured at three locations along the width direction of the test piece, and the average value was calculated as the basis weight of the entire composite fiber sheet (fiber sheet).
(Iii) Fabric weight of the nonwoven fabric layer (A):
The basis weight of the nonwoven fabric layer (A) was obtained by subtracting the basis weight of the nonwoven fabric layer (B) obtained in (i) above from the basis weight of the entire composite fiber sheet (fiber sheet) obtained in (ii) above.

(5) Thickness of the nonwoven fabric layer (A), the nonwoven fabric layer (B) and the composite fiber sheet (fiber sheet):
The composite fiber sheets (fiber sheets) finally obtained in the following Examples, Comparative Examples and Reference Examples are sharp in the direction (width direction) perpendicular to the length direction of the composite fiber sheets (fiber sheets). Cut the fiber perpendicularly in the thickness direction so that the fiber is not crushed with a simple razor, vacuum-deposit gold on the cut section, then photograph with a scanning electron microscope (SEM) (scale magnification that can accommodate all sections), non-woven fabric The thickness of the layer (A), the thickness of the nonwoven fabric layer (B), and the thickness of the entire composite fiber sheet (fiber sheet) were determined.

(6) Density of nonwoven fabric layer (A), nonwoven fabric layer (B) and composite fiber sheet (fiber sheet):
The nonwoven fabric layer (A) obtained in (4), the nonwoven fabric layer (B) and the basis weight of the composite fiber sheet (fiber sheet), and the nonwoven fabric layer (A) and nonwoven fabric layer (B) obtained in (5) above. The apparent density of the nonwoven fabric layer (A), the nonwoven fabric layer (B), and the composite fiber sheet (fiber sheet) was determined from the thickness of the composite fiber sheet (fiber sheet).

(7) Measurement of the number of exposed portions of the inorganic antibacterial fine particles on the surface of the nonwoven fabric layer (A) of the composite fiber sheet (fiber sheet):
(I) Number of exposed portions of 1/100 or more of inorganic antibacterial fine particles:
Test pieces (length × width = 5 cm × 5 cm) were collected from the composite fiber sheets (fiber sheets) finally obtained in the following examples, comparative examples and reference examples, and the surface of the nonwoven fabric layer (A) in the test pieces. The central portion (portion centering on the intersection of diagonal lines) was photographed at a magnification of 2000 using a scanning electron microscope (SEM). Draw a square with a side of 14 cm on the photo [a square with a side of 100 μm on an actual composite fiber sheet (fiber sheet)] with the center of the photograph (intersection of diagonal lines) as the center point. The portion where the inorganic antibacterial agent fine particles existing within the range of the above are picked up and the diameter is measured, and among those exposed portions, 1/100 or more of the inorganic antibacterial fine particles are The number of exposed portions is totaled, and from the total number, 1 / of inorganic antibacterial fine particles per 1.0 × 10 ⁻² mm ² of the surface of the nonwoven fabric layer (A) of the composite fiber sheet (fiber sheet). The number of 100 or more exposed locations was determined. Ten test pieces were prepared, the same measurement was performed 10 times, and the average value was adopted.

(Ii) Number of locations where the inorganic antibacterial agent fine particles are exposed in an area of 0.01 μm ² or more:
After measuring the size and number of exposed portions of 1/100 or more of the inorganic antibacterial fine particles in (i) above, the inorganic antibacterial agent is in the same region as the measurement range (measurement region) of (i) in the SEM photograph. Pick up the locations where the fine particles are exposed on the surface of the polyolefin fiber, measure the area of the locations, count the number of locations where the inorganic antibacterial agent fine particles are exposed in an area of 0.01 μm ² or more, and composite fiber sheet The number of “locations exposed in an area of 0.01 μm ² or more” per 1.0 × 10 ⁻² mm ² of the nonwoven fabric layer (A) surface of the (fiber sheet) was determined. Ten test pieces were prepared, the same measurement was performed 10 times, and the average value was adopted.
In addition, the area of the location where the inorganic antibacterial fine particles are exposed on the surface of the polyolefin fiber is, for example, the weight ( By measuring wb) and measuring the weight (wa) of the reference area S (for example, vertical × horizontal = 10 μm × 10 μm square) in the same SEM photograph, it can be obtained from the following formula (2).

Area of exposed portion of inorganic antibacterial agent fine particles = S × (wb / wa) (2)

(8) Content of inorganic antibacterial fine particles per unit area of the composite fiber sheet (fiber sheet):
The basis weight (M) (g / m ² ) of the nonwoven fabric layer (A) in the composite fiber sheet (fiber sheet), and the content of inorganic antibacterial fine particles in the polyolefin fibers (a) constituting the nonwoven fabric layer (A) ( N) The content (g / m ² ) of the inorganic antibacterial fine particles per unit area (1 m ² ) of the composite fiber sheet (fiber sheet) was determined from the product with (mass%).

(9) Dust filtration performance (dust collection efficiency) and pressure loss of composite fiber sheet (fiber sheet):
(I) From a composite fiber sheet (fiber sheet) after electret processing obtained in the following examples, comparative examples and reference examples, a circular test piece having a diameter of 110 mm was collected, and the test piece was subjected to dust filtration performance. The measurement device ("AP6310FP" manufactured by Shibata Kagaku Co., Ltd.) was attached to a measurement cell (diameter of filtration surface = 85 mm).
(Ii) Using silica dust having a diameter of 2 μm or less and a number average particle diameter of 0.5 μm as test dust, preparing dust-containing air having a concentration of the dust (silica dust) of 30 ± 5 mg / m ³ did.
(Iii) The dust (silica dust) -containing air prepared in (ii) was passed through the measurement cell prepared in (i) at a flow rate of 30 L / min for 1 minute. At this time, using the light scattering light quantity integration type detection device, the concentration of dust in the air upstream of the cell (pre-filtration air) and the concentration of dust in the air downstream of the cell (air after filtration) And measured.
(Iv) The dust collection efficiency (%) was calculated from the following formula (3), where D1 is the dust concentration on the upstream side of the cell measured in (iii) and D2 is the dust concentration on the downstream side of the cell. .

Dust collection efficiency (%) = {D1-D2) / D1} × 100 (3)

(V) At the time of measuring the dust collection efficiency of (i) to (iv) above, a fine differential pressure gauge is arranged between the upstream side and the downstream side of the measurement cell in the dust filtration performance measuring device, and the dust-containing air is 30 L. The differential pressure (pressure loss) (Pa) was measured while flowing through the measurement cell at a flow rate of / min.

(10) Air permeability of the composite fiber sheet (fiber sheet):
The air permeability of the composite fiber sheet (fiber sheet) after electret processing obtained in the following examples, comparative examples and reference examples is determined according to JIS L1906 (general long fiber nonwoven fabric test method) by the Frazier method. It was measured.

(11) Antibacterial activity (bacteriostatic activity value) of the composite fiber sheet (fiber sheet):
About the composite fiber sheet (fiber sheet) after electret processing obtained in the following examples, comparative examples, and reference examples, an antibacterial test was conducted according to JIS L1902, “Antimicrobial test method for textiles”, and bacteriostatic Activity values were determined.
The higher the bacteriostatic activity value, the better the antibacterial action.
The test conditions adopted are as follows.
-Bacterial solution conditions: 1 / 20NB, 0.2ml
-Action conditions: 37 ° C, 18 hours-Bacterial species: Staphylococcus aureus-Bacteriostatic activity value: Logarithmic difference in the number of viable bacteria before and after the action time
Bacteriostatic activity value = Log (a / b)
a = viable count after 18 hours of standard cloth
b = viable cell count after 18 hours of composite fiber sheet or fiber sheet

(12) Antiviral properties of the composite fiber sheet (fiber sheet):
For composite fiber sheets (fiber sheets) after electret processing obtained in the following examples, comparative examples and reference examples, antiviral tests were conducted according to JIS Z2801 “Antimicrobial processed products-antimicrobial test methods and antimicrobial effects”. went.
The test conditions adopted are as follows.
・ Bacteria: Influenza A virus (A / New caledonia / 20/99)
-Bacterial conditions: amount of virus acting 0.2ml
-Action conditions: 25 ° C, 24 hours-Effect determination: When the virus infection titer was 10% or less of the initial value, it was determined as "effective", and when it exceeded 10%, it was determined as "no effect".

Example 1
(1) Polypropylene (MFR = 700 g / 10 min) was used with a general melt blow equipment, spinning temperature 280 ° C., air temperature 290 ° C., air pressure 1.2 kg / cm ² , single hole discharge amount 0.4 g / Nonwoven fabric layer (B) [nonwoven fabric layer (having a basis weight and average fiber diameter shown in Table 1 below) by melt blow spinning at a hole / minute, number of spinning holes in the die of 2850 (arranged in a single row) and a collection distance of 30 cm B) Nonwoven fabric sheet] was produced.
(2) (i) Silver-based inorganic antibacterial fine particles (Toagosei Co., Ltd.) having 80 parts by mass of polypropylene (α) (MFR = 700 g / 10 min) supporting silver ions on an inorganic ion exchanger mainly composed of zirconium phosphate. A masterbatch containing silver-based inorganic antibacterial agent fine particles was prepared by blending 20 parts by mass of “NOVALON AG300” manufactured by the company, average particle size 1 μm, approximately cubic shape).
(Ii) The masterbatch prepared in the above (i) and polypropylene (β) (MFR = 700 g / 10 min) are mixed at a mass ratio of masterbatch: polypropylene (β) = 1: 1, and a general melt blow Using equipment, spinning temperature is 280 ° C, air temperature is 290 ° C, air pressure is 1.2kg / cm ² , single hole discharge is 0.1g / hole / minute, number of spinning holes in the die is 2850 (1 row arrangement) The nonwoven fabric layer (A) / nonwoven fabric layer (A) is formed by performing melt blow spinning on the nonwoven fabric layer (B) [nonwoven fabric sheet for nonwoven fabric layer (B)] produced in (1) above. A composite fiber sheet comprising B) was produced.

(3) About the composite fiber sheet obtained in (ii) of (2) above, the thickness of the composite fiber sheet, the basis weight and thickness of the nonwoven fabric layer (A) in the composite fiber sheet, and the polypropylene fiber constituting the nonwoven fabric layer (A) Average fiber diameter, number of exposed portions of inorganic antibacterial fine particles in nonwoven fabric layer (A), thickness of nonwoven fabric layer (B), composite fiber sheet, density of nonwoven fabric layer (A) and nonwoven fabric layer (B), composite fiber sheet The content of the inorganic antibacterial agent fine particles per unit area was determined by the method described above, and as shown in Table 1 below.
(4) Using general electret equipment, on the composite fiber sheet obtained in (ii) of (2) above, the distance between the needle electrode and the roll electrode is 25 mm, the applied voltage is −25 KV, and the temperature is 80 ° C. Electret processing was performed under conditions to produce a charged composite fiber sheet.
(5) For the charged composite fiber sheet obtained in (4) above, the dust collection efficiency, pressure loss, air permeability, antibacterial properties and antiviral properties were measured or evaluated by the method described above. 1 as shown.

Example 2
(1) In (1) of Example 1, the basis weight of the nonwoven fabric layer (B) [nonwoven fabric sheet for nonwoven fabric layer (B)] was changed to 20 g / m ^2, and in (ii) of Example 1 (2) A composite fiber sheet composed of the nonwoven fabric layer (A) / nonwoven fabric layer (B) was produced by performing the same operation as in Example 1 except that the basis weight of the nonwoven fabric layer (A) was changed to 1.0 g / m ² .
(2) About the composite fiber sheet obtained by said (1), the thickness of a composite fiber sheet, the fabric weight and thickness of the nonwoven fabric layer (A) in a composite fiber sheet, the average fiber diameter of the polypropylene fiber which comprises a nonwoven fabric layer (A) The number of exposed portions of the inorganic antibacterial fine particles in the nonwoven fabric layer (A), the thickness of the nonwoven fabric layer (B), the density of the composite fiber sheet, the nonwoven fabric layer (A) and the nonwoven fabric layer (B), and the unit area of the composite fiber sheet When the content of the inorganic antibacterial agent fine particles was determined by the method described above, it was as shown in Table 1 below.
(3) The composite fiber sheet obtained in (1) was subjected to electret processing in the same manner as in (4) of Example 1 to produce a charged composite fiber sheet.
(4) The charged composite fiber sheet obtained in (3) above was measured or evaluated for dust collection efficiency, pressure loss, air permeability, antibacterial properties, and antiviral properties by the method described above. 1 as shown.

<< Comparative Example 1 >>
(1) As a nonwoven fabric sheet for the nonwoven fabric layer (B), a spunbond nonwoven fabric made of polypropylene fibers (weight per unit area 30 g / m ² , thickness 0.26 mm, average fiber diameter of polypropylene fibers constituting the nonwoven fabric sheet 15 μm) is used. The nonwoven fabric layer (A) was formed on the spunbonded nonwoven fabric by melt blow spinning so that the basis weight of the nonwoven fabric layer (A) was 5 g / m ² and the thickness of the nonwoven fabric layer (A) was 0.05 mm. Except for the above, the same procedure as in Example 1 (2) was carried out to produce a composite fiber sheet composed of the nonwoven fabric layer (A) / nonwoven fabric layer (B).
(2) About the composite fiber sheet obtained by said (1), the thickness of a composite fiber sheet, the fabric weight and thickness of the nonwoven fabric layer (A) in a composite fiber sheet, the average fiber diameter of the polypropylene fiber which comprises a nonwoven fabric layer (A) The number of exposed portions of the inorganic antibacterial fine particles in the nonwoven fabric layer (A), the thickness of the nonwoven fabric layer (B), the density of the composite fiber sheet, the nonwoven fabric layer (A) and the nonwoven fabric layer (B), and the unit area of the composite fiber sheet When the content of the inorganic antibacterial agent fine particles was determined by the method described above, it was as shown in Table 1 below.
(3) The composite fiber sheet obtained in (1) above was subjected to electret processing in the same manner as in (4) of Example 1 to produce a charged composite fiber sheet.
(4) The charged composite fiber sheet obtained in (3) above was measured or evaluated for dust collection efficiency, pressure loss, air permeability, antibacterial properties, and antiviral properties by the method described above. 1 as shown.

<< Comparative Example 2 >>
(1) Polypropylene (MFR = 700 g / 10 min) was used with a general melt blow equipment, spinning temperature 280 ° C., air temperature 290 ° C., air pressure 1.2 kg / cm ² , single hole discharge amount 0.4 g / Non-woven fabric layer (B) [nonwoven fabric layer (having a basis weight and average fiber diameter shown in Table 1 below), melt blow spinning at a hole / minute, number of spinning holes in the die of 2850 (arranged in a single row) and a collection distance of 30 cm B) Nonwoven fabric sheet] was produced.
(2) (i) 80 parts by mass of polypropylene (α) (MFR = 50 g / 10 min), the same silver-based inorganic antibacterial fine particles used in Example 1 (“Novalon AG300” manufactured by Toagosei Co., Ltd.), average particles A master batch containing fine particles of silver-based inorganic antibacterial agent was prepared by blending 20 parts by mass (diameter: 1 μm, approximately cubic).
(Ii) The masterbatch prepared in the above (i) and polypropylene (β) (MFR = 700 g / 10 min) are mixed at a mass ratio of masterbatch: polypropylene (β) = 1: 1, and a general melt blow On the nonwoven fabric layer (B) [nonwoven fabric sheet for nonwoven fabric layer (B)] produced in the above (1) using the same conditions as in (ii) of (2) of Example 1, using the equipment The nonwoven fabric layer (A) was formed by melt blow spinning, and a composite fiber sheet composed of the nonwoven fabric layer (A) / nonwoven fabric layer (B) was produced.

(3) About the composite fiber sheet obtained in (ii) of (2) above, the thickness of the composite fiber sheet, the basis weight and thickness of the nonwoven fabric layer (A) in the composite fiber sheet, and the polypropylene fiber constituting the nonwoven fabric layer (A) Average fiber diameter, number of exposed portions of inorganic antibacterial fine particles in nonwoven fabric layer (A), thickness of nonwoven fabric layer (B), composite fiber sheet, density of nonwoven fabric layer (A) and nonwoven fabric layer (B), composite fiber sheet When the content of the inorganic antibacterial fine particles per unit area was measured by the method described above, it was as shown in Table 1 below.
(4) The composite fiber sheet obtained in (ii) of (2) above was subjected to electret processing in the same manner as in (4) of Example 1 to produce a charged composite fiber sheet.
(5) For the charged composite fiber sheet obtained in (4) above, the dust collection efficiency, pressure loss, air permeability, antibacterial properties and antiviral properties were measured or evaluated by the method described above. 1 as shown.

<< Comparative Example 3 >>
(1) (i) 80 parts by mass of polypropylene (α) (MFR = 50 g / 10 min), the same silver-based inorganic antibacterial fine particles used in Example 1 (“Novalon AG300” manufactured by Toagosei Co., Ltd.), average particles A master batch containing fine particles of silver-based inorganic antibacterial agent was prepared by blending 20 parts by mass (diameter: 1 μm, approximately cubic).
(Ii) The masterbatch prepared in the above (i) and polypropylene (β) (MFR = 700 g / 10 min) are mixed at a mass ratio of masterbatch: polypropylene (β) = 1: 1, and a general melt blow Using equipment, spinning temperature is 280 ° C, air temperature is 290 ° C, air pressure is 1.2kg / cm ² , single hole discharge is 0.4g / hole / minute, number of spinning holes in the die is 2850 (1 row arrangement) Then, melt blow spinning was carried out to produce a fiber sheet [non-woven fabric layer (A) single fiber sheet] composed of polypropylene fibers containing fine particles of inorganic antibacterial agent.
(2) Regarding the fiber sheet obtained in (ii) of (1) above, the fiber sheet thickness, basis weight, density, average fiber diameter of polypropylene fibers constituting the fiber sheet, and exposure of inorganic antibacterial fine particles in the fiber sheet When the content of the inorganic antibacterial fine particles per unit area of the fiber sheet per unit area was determined by the method described above, it was as shown in Table 1 below.
(3) The fiber sheet obtained in (ii) of (1) above was subjected to electret processing in the same manner as in (4) of Example 1 to produce a charged fiber sheet.
(4) For the charged fiber sheet obtained in (3) above, the dust collection efficiency, pressure loss, air permeability, antibacterial properties and antiviral properties were measured or evaluated by the method described above. It was as shown in.

<< Reference Example 1 >>
(1) (i) 80 parts by mass of polypropylene (α) (MFR = 700 g / 10 min), the same silver-based inorganic antibacterial fine particles used in Example 1 (“Novalon AG300” manufactured by Toagosei Co., Ltd.), average particles A master batch containing fine particles of silver-based inorganic antibacterial agent was prepared by blending 20 parts by mass (diameter: 1 μm, approximately cubic).
(Ii) The masterbatch prepared in (i) above and polypropylene (β) (MFR = 700 g / 10 min) are mixed at a mass ratio of masterbatch: polypropylene (β) = 1: 9, and a general meltblown Using equipment, spinning temperature is 280 ° C, air temperature is 290 ° C, air pressure is 1.2kg / cm ² , single hole discharge is 0.1g / hole / minute, number of spinning holes in the die is 2850 (1 row arrangement) Then, melt blow spinning was carried out to produce a fiber sheet [non-woven fabric layer (A) single fiber sheet] composed of polypropylene fibers containing fine particles of inorganic antibacterial agent.
(2) Regarding the fiber sheet obtained in (ii) of (1) above, the fiber sheet thickness, basis weight, density, average fiber diameter of polypropylene fibers constituting the fiber sheet, and exposure of inorganic antibacterial fine particles in the fiber sheet When the content of the inorganic antibacterial fine particles per unit area of the fiber sheet per unit area was determined by the method described above, it was as shown in Table 1 below.
(3) The fiber sheet obtained in (ii) of (1) above was subjected to electret processing in the same manner as in (4) of Example 1 to produce a charged fiber sheet.
(4) For the charged fiber sheet obtained in (3) above, the dust collection efficiency, pressure loss, air permeability, antibacterial properties and antiviral properties were measured or evaluated by the method described above. It was as shown in.

As seen in Table 1 above, the composite fiber sheets of Examples 1 and 2 are provided with the above-mentioned requirements << 2a >> to << 2e >> and requirements << 3a >> to << 3c >>. Despite the small content of inorganic antibacterial particles per unit area of 0.15 g / m ² or 0.10 g / m ² , the content of inorganic antibacterial particles per unit area is 0.34 g / m Like the fiber sheet of Reference Example 1 having a large m ² , the bacteriostatic activity value is high, the antibacterial property is excellent, and the antiviral property is also excellent. Furthermore, the composite fiber sheets of Examples 1 and 2 have a high dust collection efficiency value, a small pressure loss, a large air permeability, and an excellent filter performance.
On the other hand, in the composite fiber sheet of Comparative Example 1, the average fiber diameter of the polypropylene fibers constituting the nonwoven fabric layer (B) is too large as 15.2 μm and does not have the requirement << 3a >> in the present invention, and further the nonwoven fabric. Since the basis weight of the layer (B) is too large as 35 g / m ² and does not have the requirement << 3b >> in the present invention, the dust collection efficiency and the air permeability are small compared to the composite fiber sheets of Examples 1 and 2. The filter performance is inferior.
In addition, the composite fiber sheet of Comparative Example 2 and the fiber sheet of Comparative Example 3 have few exposures of inorganic antibacterial fine particles from the surface of the polypropylene fiber constituting the nonwoven fabric layer (A) (fiber sheet), and the requirements in the present invention Since <3e> is not provided, the fiber sheet of Comparative Example 3 in particular has a high content of inorganic antibacterial fine particles per unit area of the fiber sheet of 1.80 g / m ² , but the example 1 Compared with the composite fiber sheets of No. 2 and No. 2, the antibacterial property (bacteriostatic activity value) is low, and the antiviral property is inferior.
The fiber sheet of Reference Example 1 has high antibacterial and antiviral properties like the composite fiber sheets of Examples 1 and 2, but compared to the composite fiber sheets of Examples 1 and 2, High content of inorganic antibacterial particles per unit area, large pressure loss, and low air permeability.

  The composite fiber sheet of the present invention has a high antibacterial action despite the fact that the amount of inorganic antibacterial fine particles used per unit area is small and the proportion of inorganic antibacterial fine particles used in the entire composite fiber sheet is reduced. In addition to the stable collection of harmful microorganisms and dust, the pressure loss is low, the filter performance is good, and the strength and light weight are excellent. It can be effectively used in various applications that require high antibacterial effects, hygiene, and high filter performance, such as sanitary products, food packaging materials, liquid filters, and gas filters.

Claims (7)

<< 1 >> A non-woven fabric layer (A) composed of a polyolefin fiber (a) produced from a polyolefin resin composition containing inorganic antibacterial fine particles and a polyolefin fiber (b) not containing inorganic antibacterial fine particles A composite fiber sheet in which only the nonwoven fabric layer (B) is laminated ,
<< 2 >> The nonwoven fabric layer (A) is
<< 2a >> The content of the inorganic antibacterial fine particles in the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is 5 to 20% by mass;
<< 2b >> The average fiber diameter of the polyolefin fibers (a) constituting the nonwoven fabric layer (A) is 0.1 to 2.3 μm;
<< 2c >> The basis weight is 0.1 to 5 g / m ² ;
<< 2d >> thickness of 0.01 to 0.1 mm; and
<< 2e >> 1 area where 1/100 or more of the volume of the inorganic antibacterial fine particles is exposed on the surface of the polyolefin fiber (a) per 1.0 × 10 ⁻² mm ^{2 of the} nonwoven fabric layer (A) Or at least one portion where the inorganic antibacterial fine particles are exposed on the surface of the polyolefin fiber (a) with an area of 0.01 μm ² or more;
Requirements << 2a >> to << 2e >>
<< 3 >> The nonwoven fabric layer (B) is
<< 3a >> The average fiber diameter of the polyolefin fibers (b) constituting the nonwoven fabric layer (B) is 2.5 to 10 μm;
<< 3b >> The basis weight is 5 to 30 g / m < ² >; and
<3c> 0.1 to 0.3 mm in thickness;
A composite fiber sheet comprising the requirements << 3a >> to << 3c >>.   The composite fiber sheet according to claim 1, wherein the inorganic antibacterial fine particles contained in the polyolefin fibers (a) constituting the nonwoven fabric layer (A) have an average particle diameter of 0.01 to 10 µm.   The composite fiber sheet according to claim 1 or 2, wherein a ratio of [weight of nonwoven fabric layer (A)]: [weight of nonwoven fabric layer (B)] is 1: 100 to 1: 5. The composite fiber sheet according to any one of claims 1 to ³ , wherein the density is 0.05 to 0.12 g / cm ³ . A polyolefin resin in which the polyolefin fiber (a) constituting the nonwoven fabric layer (A) is a mixture of a polyolefin resin (α) containing inorganic antibacterial particles and a polyolefin resin (β) not containing inorganic antibacterial particles. The difference between the melt flow rate (MFR _α ) (g / 10 min) of the polyolefin resin (α) and the melt flow rate (MFR _β ) (g / 10 min) of the polyolefin resin (β). The composite fiber sheet according to any one of claims 1 to 4, wherein the composite fiber sheet is formed from a polyolefin resin composition having an absolute value satisfying the following mathematical formula (1).

0 ≦ | MFR _α −MFR _β | ≦ 600 (1)

[However, MFR _α and MFR _β are both measured according to JIS K 7210 under conditions of a temperature of 230 ° C., a load of 2.16 kg, and a measurement time of 10 minutes (unit: g / 10 minutes). It is. ]   The composite fiber sheet according to any one of claims 1 to 5, wherein the nonwoven fabric layer (A) and the nonwoven fabric layer (B) are layers made of a nonwoven fabric produced by a melt blow method.   The filter using the composite fiber sheet of any one of Claims 1-5.