JP2011132628A - Antimicrobial melt-blown nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antimicrobial melt-blown nonwoven fabric having excellent spinning stability. <P>SOLUTION: The antimicrobial melt-blown nonwoven fabric providing low pressure drop and high capturing rate is obtained by kneading antimicrobial agent particles having nanometer sizes in a fiber. The antimicrobial melt-blown nonwoven fabric having the high spinning stability and the high antimicrobial properties comprises ultrafine fibers containing the antimicrobial agent particles not inhibiting the spinning stability. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrafine fiber nonwoven fabric, and more particularly to an antibacterial meltblown nonwoven fabric that can be suitably used in applications such as masks, filters, and wipers.

  Conventionally, many techniques for imparting antibacterial properties to textile products are known. However, when a nonwoven fabric is provided with antibacterial properties and electret properties on an ultra-fine fiber nonwoven fabric with an average fiber diameter of less than 5 μm, there are many technical issues. The technology that solved the problem was not satisfactory as described below. As a document relating to such technology, Patent Document 1 discloses an antibacterial agent chemical solution adhesion processing method on an electret nonwoven fabric. However, since this material has an electrical resistance value on the fiber surface that is affected by the chemical solution of the antibacterial agent particles, the electret stability is extremely poor. In Patent Document 2, an antibacterial agent particle is replaced with an inorganic antibacterial zeolite having a very large particle size of 0.5 to 3.0 μm (antibacterial metal ion of crystalline aluminosilicate) in a fiber having a fiber diameter of 50 μm. An air filter in which an antibacterial nonwoven fabric kneaded with an electret nonwoven fabric is laminated. In this case, antibacterial effect can be expected against bacteria trapped by the antibacterial processed nonwoven fabric, but the bacteria and viruses are very small, 0.01 to several μm, so the upstream nonwoven fabric processed with rough antibacterial processing However, the antibacterial technology lacked practicality because it was captured by the electret non-woven fabric layer having a higher density and higher collection efficiency and no antibacterial properties, while being hardly captured.

In Patent Document 3, a synthetic organic polymer having a volume resistivity of 10 ¹³ Ω · cm or more contains a heat stabilizer (radical scavenger) such as hindered amine or hindered phenol in the range of 0.01 to 2% by weight and inorganic. An antibacterial electret material containing 0.1 to 4% by weight of antibacterial agent particles is described. However, since zeolite is a natural material, even if it is crushed and classified, its particle size is widely distributed and the primary particle size is 0.5 to 3.0 μm. When ejected, the particles agglomerated and settled in the polymer to increase the particle size, and the nozzles were frequently clogged, making it impossible to fabricate a melt blown nonwoven fabric with a fiber diameter of 2 μm or less. Moreover, although the Example of patent document 4 shows the electret antibacterial nonwoven fabric of average fiber diameter 1.5micrometer which spun the polymer containing the inorganic antibacterial agent particle of average particle diameter 0.8micrometer by the melt blow method, This is a technique with no description of the particle diameter and material of the antibacterial agent particles used to obtain a melt blown nonwoven fabric having a diameter of 0.8 μm or less.

  Meanwhile, Patent Document 6 discloses a technique related to antibacterial fibers in which nanometer-sized inorganic antibacterial particles are kneaded. However, in the description of the technical content, the particle diameter of silver phosphate silver or the like is used as the antibacterial agent particles to be used. Although antibacterial particles in the range of 0.01 μm to 3 μm are mentioned, the particle size of Novalon AG300 (Toa Gosei Chemical Co., Ltd.) mentioned in the examples is 0.9 μm, and Sea Bio (Seawater Chemical Laboratory) ) Was found to be 0.2 μm from the manufacturer technical data survey, no technology using antibacterial particles of less than 0.2 μm was disclosed.

  On the other hand, Patent Document 5 discloses an antibacterial fiber nonwoven fabric in which 0.1 to 1% by weight of a dispersant-containing nanometer-order silver particle is kneaded into a fiber having a fiber diameter of several nm to several hundred nm (preferably 50 nm to 800 nm). Although the manufacturing technology is disclosed. This nanometer-order fiber is produced by electrospinning a solution in which a polymer and nanometer-order silver particles are dissolved and dispersed in a solvent, and is different from the melt spinning method. It was adopted. The microfiber layer is described as containing 0.1 to 1% by weight of nanometer-order silver particles in the melt-spun polypropylene fiber. The nanometer-order silver particles used here are dispersants. Contains nanometer-order silver particles that are described as melting at a temperature much lower than the melting point of the polypropylene resin, and is a technique using non-melting nanometer-order antibacterial particles used in the present invention. It was a completely different technology. As these background technologies show, the antibacterial agent particle diameter kneaded into the resin by the melt spinning method is up to 200 nm, and the technology for stably producing an antibacterial meltblown nonwoven fabric using particles smaller than that, low pressure loss, A technique for obtaining an electret antibacterial meltblown nonwoven fabric having a high trapping property has not been disclosed.

JP 62-42716 A Japanese Patent Laid-Open No. 3-186309 Japanese Patent Laid-Open No. 5-190389 JP 2008-75226 A JP 2008-95266 A JP-A-9-176949

  The present invention relates to an antibacterial meltblown nonwoven fabric that solves the above problems, and an object thereof is to provide an ultrafine fiber nonwoven fabric having high performance antibacterial properties, antiviral properties, antiallergenic properties, deodorizing properties, and electret properties.

To achieve the above object, the present invention has one of the following configurations.
(1) An antibacterial meltblown nonwoven fabric having an average fiber diameter of 40 μm or less, including antibacterial particles having a primary particle diameter of less than 200 nm.
(2) The antibacterial meltblown nonwoven fabric according to (1), wherein the antibacterial agent particles are silver sulfide particles or / and silver sulfide particles impregnated with silica.
(3) The antibacterial meltblown nonwoven fabric according to (1) or (2), wherein a plurality of fiber groups having different antibacterial agent content are mixed.
(4) It has a plurality of fiber groups having different average fiber diameters, and among them, a fiber group having an average fiber diameter of 6 μm or more occupies 20% or more of the total fiber volume, according to any one of (1) to (3) Antibacterial melt blown nonwoven fabric.
(5) The antibacterial meltblown nonwoven fabric according to any one of (1) to (4), which is electretized.
(6) A filter using the antibacterial meltblown nonwoven fabric according to any one of (1) to (5).
(7) A filtration device using the antibacterial meltblown nonwoven fabric according to any one of (1) to (5).

The antibacterial meltblown nonwoven fabric of the present invention has the following excellent effects.
(1) Functional appeal such as antibacterial, antiviral, antifungal, etc. is performed with antibacterial particles having a particle diameter of 200 nm or less that do not impair spinnability even in spinning of ultrafine fiber yarns with a fiber diameter of 0.1 μm. Can be obtained.
(2) Sulfur of silver sulfide particles of antibacterial agent particles has high antifungal properties and has inactivation performance against various types of fungi. Silver also has high antibacterial and antiviral properties. Therefore, by combining sulfur and silver, high antibacterial properties, antifungal properties, antiviral properties (hereinafter referred to as antibacterial properties) and antiallergenic properties due to synergistic effects can be obtained.
(3) In addition, nanometer-order silver particles have a catalytic action that acts on oxygen to transform it into highly reactive negatively charged oxygen (oxygen radicals). For this reason, antibacterial properties can be obtained against bacteria, molds, viruses, and allergens that are not directly in contact with silver sulfide. In addition, deodorizing properties can be obtained for malodorous components.
(4) Since the effects (1) to (3) have an antibacterial surface and a catalytic surface on the surface of the ultrafine fibers, a large antibacterial property, antiallergenic property and deodorizing property can be obtained with a small amount of use.
(5) The structure of the nonwoven fabric is a mixture of a plurality of extra-thick fiber groups and extra-fine fiber groups, and the extra-fine fibers are supported by the extra-thick fibers and are not easily crushed. For this reason, it is possible to obtain a higher collection performance with a lower pressure loss than a conventional nonwoven fabric composed of only one fiber group having a thin fiber diameter.
(6) Since the antibacterial agent particle content and the average fiber diameter are different in the fiber group, high electret properties and high antibacterial properties can be obtained.

  Hereinafter, preferred embodiments of the antibacterial meltblown nonwoven fabric according to the present invention will be described in detail. The antibacterial agent particles of the present invention will be described. Antibacterial agent particles are kneaded into fibers made of organic polymers. As the antibacterial agent particles, colloidal particles of metals such as copper, zinc, and silver that can generate metal ions having a primary particle diameter of less than 200 nm are preferably used. Silver sulfide particles, copper sulfide particles, silver nitrate Particles, zinc oxide particles, zinc oxide aluminum alloy particles and the like can be used. Among these, silver sulfide particles and zinc oxide particles are the optimum substances.

  Silver sulfide particles are silver colloidal sulfides in which silver is bonded to sulfur atoms. The primary particle diameter is less than 200 nm, preferably 100 nm or less, more preferably 50 nm or less, and most preferably 2 nm to 50 nm. In particular, when the primary particle diameter is 2 nm to 20 nm, there is no aggregation, and the polymer fluidity is good, so that the holes with a spinning nozzle hole diameter of 0.05 to 0.2 mm are not blocked, and high spinnability can be obtained. . For this reason, it is possible to stably produce ultrafine fibers having an average fiber diameter of less than 0.1 μm. For the primary particles, the surface or cut surface of the resin or fiber is observed using a transmission electron microscope, and particles that do not overlap or aggregate and cannot be further divided are defined as primary particles.

  The combination of silver and sulfur is very effective in making up for the weaknesses of each antibacterial property. In other words, silver has high antibacterial and antiviral properties, but weak antibacterial properties against some fungi. On the other hand, although sulfur is inferior in antiviral properties, it exhibits high antibacterial properties against most fungi, bacteria and algae. Since the antibacterial agent particles used in the present invention are obtained by binding a sulfur atom to silver, antibacterial and antiviral properties against fungi, bacteria and algae can be obtained simultaneously by a synergistic effect. For this reason, it can be used effectively not only with air but also with liquid filtration.

  The antibacterial agent can also be used in the form of silica-impregnated silver sulfide particles in which sulfur atoms and silver are bonded as complex compounds to silica particles or colloidal silica particles. Although the silver sulfide particles are yellow, the silica-impregnated silver sulfide particles are white and can be suitably used particularly when it is desired to obtain a white product. Next, antibacterial properties and deodorizing properties due to the catalytic effect of the antibacterial agent will be described.

  Nanometer-sized silver has a catalytic action. Catalytic action refers to the effect of changing oxygen in the air or liquid to oxygen with a negative charge (oxygen radical). It is thought that this oxygen radical is taken up by the protein component of the fungus or killed by drawing out the OH radical, or inactivated by changing the molecular chain structure of the protein. This catalytic action is recognized in the case of silver sulfide particles having a particle size of nanometer size or silica-added silver sulfide particles, and is obtained by contacting oxygen with the surface of nanometer size silver component particles exposed on the fiber surface. The effect of this catalytic action is that antibacterial properties are obtained by the action of the oxygen radicals floating on the collected bacteria, viruses and allergens (hereinafter referred to as fungi) that are not in direct contact with the antibacterial agent particles. . In addition, most antibacterial agents using conventional metal ions exhibit antibacterial properties by the action of metal ions dissolved in water, but since this catalytic action is effective even in dry air, The antibacterial effect can be obtained even when the dust containing the fungi is dry or moist. In addition, the same mechanism can provide a deodorizing property because of the catalysis of malodorous gas substances.

  The amount of addition when silver sulfide particles are used as the antibacterial agent particles will be described. The addition amount of silver sulfide particles is 0.008% to 0.2% by weight or less of the weight of the nonwoven fabric. If it is 0.008% by weight or less, it is difficult to obtain antibacterial properties, but if it exceeds 0.2% by weight, aggregates increase, resulting in nozzle clogging and a decrease in spinnability due to an increase in polymer viscosity. Further, since silver sulfide particles have electrical conductivity, if too much is added, the electrical resistance value of the fiber surface is lowered, so that the stability of the electret charge is impaired, and an adverse effect occurs when obtaining an electret antibacterial nonwoven fabric. From these relationships, high antibacterial properties, electret properties, and spinnability are obtained with an addition amount of preferably 0.008 wt% to 0.15 wt% or less, optimally 0.01 wt% to 0.1 wt%. be able to.

  Next, the antibacterial melt-blown nonwoven fabric can be made into a high-performance electret antibacterial nonwoven fabric by electretization by the method described in JP-A-9-501604. Therefore, when the electret antibacterial nonwoven fabric is used as a non-woven fabric for masks and filters, fine dust and fungi are adsorbed by electret charges, and in addition to high collection ability, collected bacteria, molds and viruses Since it can be directly inactivated in terms of collecting allergen substances, it can be made into a product with high safety and health.

  In the laminated filter medium in which the conventional melt blown nonwoven fabric that does not retain antibacterial properties and the nonwoven fabric that has been subjected to antibacterial processing are laminated, antibacterial properties can be expected against bacteria trapped in the antibacterial processed nonwoven fabric, but 0 Since it was very small as .01 to several μm, it was hardly captured by the upstream nonwoven fabric subjected to rough antibacterial processing, and was collected by a melt blown nonwoven fabric having a higher density and higher antibacterial activity than the lower layer. For this reason, mold fungus gradually grew and permeated into the air downstream side, causing many problems to spore scatter from the filter medium surface. However, in the case where the ultrafine fiber itself has antibacterial properties as in the present invention, Since there is no growth of bacteria, contamination on the downstream side of the air can be prevented. For this reason, it can be suitably used as a building air conditioner, a domestic air cleaner, an automobile cabin filter, or the like. Moreover, if it is used as a wiper, high dust trapping properties can be obtained, and in order to inactivate attached bacteria and allergenic substances in a short time, a product with high safety and hygiene can be obtained even if touched by hand.

  Next, the resin used will be described. As the organic polymer that can be used in the present invention, a resin having a high spinnability that has a viscosity of 30 to 2500 MFR capable of melt blow spinning and does not carbonize even at a spinning temperature of around 200 ° C. is suitable. Polypropylene resin, polyethylene resin, polyamide resin, polyphenylene sulfite resin, polystyrene resin, polylactic acid resin, polyethylene terephthalate resin, etc. can be widely used, but when obtaining electret nonwoven fabric, A polypropylene resin, a polylactic acid resin, a polyethylene resin, a polycarbonate resin, or a polyphenylene sulfite resin can be used alone or as a copolymer resin.

  The advantage of the melt blown nonwoven fabric is that a very large fiber surface area can be utilized as an antibacterial action surface because even ultrafine fibers having a fiber diameter of 0.05 μm or more can be produced with high productivity. For this reason, even if the addition amount of the antibacterial agent is reduced, high antibacterial properties can be obtained, and there is an advantage that the fungi can be collected with high collection efficiency and directly inactivated.

The method for producing the melt blown nonwoven fabric is, for example, an example, but a melt blow nozzle die arranged with a nozzle hole diameter of 0.2 mm and a pitch of 0.6 mm is heated to a temperature of 220 ° C., and a rate of 0.1 g / min per nozzle hole. Then, the polypropylene fiber is discharged in a state where the raw material resin is melted, and a heated air stream is applied to the discharged polypropylene fiber at a temperature of 240 ° C. and a nozzle width of 16 Nm ³ / min to pull the fiber. It is possible to form a flow of ultrafine fibers, and then to collect the ultrafine fibers on a mesh air suction conveyor. In addition, a nano melt spinning method which is one type of melt blow method can be given. The nano melt spinning method is the application of ultra-low viscosity melted polymer to the surface of a rotating roller to which voltage is applied. Is the technology to get This method is desirable because a nonwoven fabric mainly having a fiber diameter of 0.05 to 1 μm can be produced.

  The antibacterial melt blown nonwoven fabric of the present invention is an antibacterial melt blown nonwoven fabric obtained by spinning an organic polymer containing antibacterial agent particles by a melt blow manufacturing method. The melt blown non-woven fabric is made by melting the resin and simply taking the time after discharge from the nozzle discharge hole, as described in a publicly known document related to antibacterial fibers by a general melt spinning method, Japanese Patent Laid-Open No. 9-176949. In the process of cooling, it is unavoidable that the antibacterial agent particles are agglomerated in the fiber core, but in the melt blow method, the discharged polymer is branched (divided) in the process of being pulled by air, and is made ultrafine and rapidly cooled. For this reason, since nanometer-sized antibacterial particles that are easily mixed with the polymer are used, fiber formation is performed with the antibacterial agent exposed on the fiber surface simultaneously with rapid cooling. For this reason, the fact that antibacterial agents are unevenly distributed does not occur.

  The average fiber diameter of the antibacterial meltblown nonwoven fabric is set to 40 μm or less because the meltblown process is a process of discharging / thinning the melted polymer into a nonwoven fabric. There is no step to stretch the chain. For this reason, the fibers are close to an unstretched state and are very brittle. This tendency is more conspicuous for thick fibers having a fiber diameter of more than 40 μm. When pleating is performed, there is a drawback that the fibers are easily broken at the bent portion. For this reason, a fiber of 40 μm or less having practicality that does not break is used. Further, the antibacterial property is more preferable as the fine fiber because the thinner the fiber, the larger the antibacterial action surface, and the higher antibacterial property can be obtained with a small amount of the antibacterial agent used. For this reason, the preferred average fiber diameter is 25 μm or less, more preferably 10 μm or less, and 0.05 μm or more is preferable as the lower limit.

  However, if it is too thin, it will be broken by rubbing, or the pressure loss will increase due to tightening, so that it is preferably 0.1 μm or more and 10 μm or less, optimally 0.1 μm or more and 7 μm or less.

  However, a melt-blown nonwoven fabric composed of fibers of 0.1 μm to 6 μm or less has no rigidity, so it is inevitable to reduce the thickness due to crushing. For this reason, the direction after winding up rather than the melt blown nonwoven fabric pressure loss of the stage collected on the conveyor winds up, and pressure loss becomes high.

  However, in the present invention, the anti-bacterial melt-blown nonwoven fabric having a low pressure loss can be obtained because the ultra-thin fiber group is mixed with the fiber group having a small average fiber diameter to prevent the collapse. That is, the antibacterial meltblown nonwoven fabric of the present invention can be an antibacterial meltblown nonwoven fabric having a different fineness mixed with a plurality of fiber groups having different average fiber diameters. Such a nonwoven fabric is characterized by low pressure loss and high collection as well as antibacterial properties.

In fact, when the effect is shown by pressure loss, a fiber group having an average fiber diameter of 1.2 μm (fiber diameter distribution range of 0.1 to 5 μm) and a fiber group having an average fiber diameter of 15 μm (fiber diameter distribution range of 10 to 25 μm), that is, an average The electret antibacterial melt-blown nonwoven fabric (weight per unit area: 12 g / m ² ) having a mixed structure of two fibers with different fiber diameters is a volume ratio of fibers having a fiber diameter of 6 μm or more in the total fiber volume constituting the nonwoven fabric. Has a pressure loss of 12 Pa and a collection efficiency of 93%. On the other hand, a fiber group having an average fiber diameter of 1.7 μm (fiber diameter distribution range: 1 to 7 μm) is required to achieve the same collection efficiency of 93% with the conventional melt blown nonwoven fabric having one fiber group, and fibers It becomes a melt blown nonwoven fabric mainly composed of ultrafine fibers not containing fibers having a diameter of 8 μm or more. However, since melt blown nonwoven fabrics composed mainly of ultrafine fibers have low rigidity, when wound up as a nonwoven fabric, it is unavoidable that the pressure loss increases because it is crushed by the winding pressure, and the pressure loss must be as high as 20 Pa.

  An antibacterial meltblown nonwoven fabric of different fineness mixed in such a manner that a very thick fiber group is mixed as a skeletal fiber that supports the thickness of the nonwoven fabric and mixed so that the ultrafine fiber group is cross-linked to the skeletal fiber as a fiber that enhances the collection performance. Since the space volume partitioned by the fiber group is not crushed by the winding pressure, the bulkiness of the ultrafine fiber group in the space is maintained. As a result, it is possible to obtain an antibacterial melt blown nonwoven fabric having a high antibacterial property utilizing a very large fiber surface area and having a low pressure loss and a high collection property.

Production of the antibacterial meltblown nonwoven fabric having such a different fineness mixed structure can be carried out as follows.
(1) A method in which two or more polymers having different melt viscosities of 3 times or more, preferably 5 times or more are mixed and discharged from a hole having a nozzle hole diameter of 0.05 to 0.2 mm, and then pulled by high-speed heated air. In this method, a difference occurs in the traction property and fiber splitting property according to the polymer viscosity, so fibers having different fiber diameters can be mixed uniformly.
(2) A method in which two or more types of polymer discharge holes having different diameters are prepared, a polymer having a high viscosity is measured from a hole having a large diameter, and a polymer having a low viscosity is measured from a small diameter and discharged, and then pulled by high-speed heated air.
(3) A method in which the polymer having the same viscosity as in (2) is pulled with high-speed heated air after being discharged while changing the discharge amount.
(4) A method in which two nozzle heads are arranged at positions facing diagonally downward, and after the discharge amount of ultra-thick and ultra-fine fibers by each nozzle, they are merged in high-speed heated air. It can be implemented by any of the above methods. Among them, the method (2) can increase the average fiber diameter difference of the fiber group.

  The very thick fiber group of the antibacterial meltblown nonwoven fabric having a mixed structure of different fineness produced by any one of the above methods will be described. The average fiber diameter of the very thick fiber group serving as the skeletal fiber is suitably 6 to 40 μm because it needs to be repulsive so as not to be crushed by the winding pressure. However, the thicker the fibers, the more damage can be prevented, but there is also an adverse effect of increasing the thickness. In addition, when spinning by the melt blow method, if the melted and discharged fibers are not cooled sufficiently until they are collected, they will adhere to the very fine yarns that are spun together and melt, or they may be fused together by very thick yarns. Therefore, the problem that bulkiness does not appear also arises. Due to these problems, a suitable average fiber diameter range is 6 to 40 μm. The thickness is preferably 6 to 30 μm, more preferably 6 to 25 μm, and most preferably 6 to 25 μm.

  On the other hand, the volume ratio between the ultrafine fiber group and the ultrathick fiber group is important in order to achieve both low pressure loss and high collection ability. The method for determining the volume ratio of the very thick fibers is to obtain the fiber diameter distribution of the antibacterial melt-blown nonwoven fabric with a mixed structure of different fineness and multiply the fiber cross-sectional area by a certain length to obtain the total fiber volume of all the fibers that make up the nonwoven fabric. It is obtained from the ratio of the volume amount of only fibers having a fiber diameter of 6 μm or more in the total fiber volume of all fibers.

  Nonwoven fabrics having a low volume ratio of very thick fibers are easily crushed and cannot prevent an increase in pressure loss. On the other hand, a nonwoven fabric with a too high volume ratio has a high pressure loss because the space volume in the nonwoven fabric layer is reduced. It also becomes difficult to increase the collection efficiency. From these balances, when the fiber volume ratio of the very thick fiber group having an average fiber diameter of 6 μm or more is within the range of 15 to 85% of the total nonwoven fabric fiber volume, low-pressure loss and high trapping property can be realized. A preferred volume ratio is 20 to 75% (volume ratio of fibers having an average fiber diameter of less than 6 μm is 25 to 80% or less), and more preferably 30 to 70% (volume ratio of fibers having an average fiber diameter of less than 6 μm is 30 to 70% or less. ), And optimally, 35-65% (volume ratio of fibers with an average fiber diameter of less than 6 μm is 35-65% or less). In addition, if the average fiber diameter difference between the very thick fiber group and the next thin fiber group is 2 μm or more, preferably 3 μm or more, and optimally 5 μm or more, the collection efficiency can be improved and low pressure loss can be achieved. is there.

  Next, the ultrafine fiber group will be described. The antibacterial meltblown nonwoven fabric, which has a mixed structure of different fineness, manufactured by the above method is composed of a plurality of fiber groups. And high collection performance can be obtained. Therefore, the average fiber diameter range of the thinnest ultrafine fiber group is 3.0 to 4.0 μm, preferably 1.5 to 3.0 μm, more preferably 0.8 to 1.5 μm, and most preferably 0.3 to 0.8μm, more preferably 0.05 to 0.3μm, but if the fiber is too thin, the strength will decrease and tearing will occur due to scratching, so practically 0.1μm to 2.0μm is appropriate. It is.

  Next, a method for realizing electret properties and high antibacterial properties will be described. For example, high antibacterial properties can be obtained by kneading a large amount of silver sulfide particles of less than 200 nm in the fiber as antibacterial agent particles. On the other hand, conductivity is exhibited by nanometer-order silver particles. Chargeability and stability may be hindered. For this reason, as a means of achieving both electret and antibacterial properties, the ultrafine fibers that are highly effective in developing high trapping properties due to the electret effect are used as electret reinforced fibers without reducing or adding the amount of silver sulfide particles. Adding extra antibacterial agent to extra-thick fiber to make it a fiber that emphasizes antibacterial properties and catalytic effects, high-capacity and anti-bacterial properties with ultra-thin fibers, medium-capturing properties and high anti-bacterial properties with extra-thick fibers, An electret antibacterial meltblown nonwoven fabric having a mixed structure of different fineness in which low-pressure loss due to bulkiness is realized can be obtained. In addition, since the combination can change the type of antibacterial agent, it is possible to provide an antibacterial melt blown nonwoven fabric excellent in antibacterial property and high collection property.

  The antibacterial melt blown nonwoven fabric of the present invention can be used as various air filters, liquid filters, wipers, fresh food cover materials, medical materials, and clothing materials, and can be used in combination with other textile products. In particular, when an electret antibacterial meltblown nonwoven fabric or an antibacterial meltblown nonwoven fabric is used as a filter, an antibacterial laminated fiber product reinforced by laminating with a support nonwoven fabric having a high reinforcing function is desirable. In addition, anti-bacterial laminated fiber products with enhanced functions by using functional non-wovens with antibacterial, antifungal, antiallergenic, antiviral, deodorant, deodorizing, etc. functions. I can do it. For example, when an antibacterial and anti-allergenic support nonwoven fabric is laminated on a support nonwoven fabric, the entire antibacterial laminated fiber product becomes antibacterial, so that the entire nonwoven fabric is inactivated with fungi and fungi and must be replaced with bare hands. Safety and hygiene is high even when touched, and it is possible to prevent the onset of hay fever due to soaring allergens.

  These electret antibacterial meltblown nonwoven fabrics, antibacterial meltblown nonwoven fabrics, and antibacterial laminated fiber products are filtered devices that have high antibacterial properties when used in various air purifiers, air conditioners, and water purifiers. can do

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the evaluation method in a present Example is as follows.

<Unit weight>
The sample is allowed to stand at room temperature of 24 ° C. and 60% RH for 8 hours or longer, and the mass of the evaluation sample is obtained. The mass per 1 m ² is corrected from the area and obtained as the basis weight of each evaluation sample. The minimum sampling area is 0.01 m ² or more.

<Measurement of collection performance>
An evaluation sample is set in an evaluation device conforming to JIS B9908 (2001) type 1 test method, general outside air is supplied from the upstream side at a filter medium penetration air velocity of 3.18 m / min, and the number of particles before and after the evaluation sample is measured using a particle counter. To obtain the collection efficiency from the following formula.
η = (1− (C _O / C _I )) × 100
C _O = number of particles having a particle size of 0.3 to 0.5 μm after passing through the evaluation filter C _I = number of particles having a particle size of 0.3 to 0.5 μm before passing through the evaluation filter.

<Antimicrobial test method-quantitative method>
In the quantitative test (bacterial solution absorption method) specified in JIS L1902 ²⁰⁰⁸ “Antimicrobial test method for textile products”, the method is carried out by covering the liquid surface with a film. The number of viable bacteria is measured by the pour plate culture method to determine the bacteriostatic activity value. The test strain used was Staphylococcus staphylococcus ATCC 6538P. In addition, a standard white cloth (cotton) was used as an unprocessed sample, and a test bacterial solution to which 0.05% of a surfactant (Tween 80) was added was used. Judgment criteria Antibacterial activity with bacteriostatic activity value of 2.0 or more.

<Antiviral test method>
Performed according to the Japan Analytical Food Analysis Center Antiviral Test Method (Influenza A, H1N1).

<Anti-fungal test method>
Conducted by Japan Chemical Fiber Inspection Association, JIS Z2911 ²⁰⁰⁰ (wet method). The following four types of fungi were used.
Aspergillus niger NBRC6341
Penicillium citrinum NBRC6352
Chaetmium globosum NBRC6347
Myrothecerium verrucaria NBRC 6113
Criterion 0: No hyphal growth is observed in the inoculated part of the sample or test piece.
1: The area of the growing part of the mycelium observed in the inoculated part of the sample or the test piece does not exceed 1/3 of the total area.
2: The area of the growth part of the mycelium recognized in the inoculated part of the sample or the test piece exceeds 1/3 of the total area.

<Anti-allergenicity>
The ELISA method test was performed. The allergen was carried out using cypress leopard mite and cedar pollen.

<MFR test method>
It carries out according to JIS K7210.
<How to find the average fiber diameter from melt blown nonwoven fabric>
The surface of the meltblown nonwoven fabric is observed with an SEM, and 200 or more fibers are randomly extracted from one area, and the fiber width is measured at the shortest distance. This operation is carried out in three areas separated by 3 cm or more, and the average fiber diameter is obtained by arithmetically averaging 600 fiber widths.

<Fiber diameter analysis and how to determine the volume ratio of very thick fibers>
The fiber diameter distribution of the whole antibacterial melt-blown nonwoven fabric with a different fineness mixed structure is obtained, and the fiber volume total amount of all the fibers constituting the nonwoven fabric is obtained by multiplying the fiber cross-sectional area by a certain length, and the fibers occupy the total fiber volume of all the fibers. It is determined from the volume ratio of only fibers having a diameter of 6 μm or more.

<Antibacterial agent analysis method>
The primary particle size is determined by observing the surface or cut surface of the resin or fiber using a transmission electron microscope, and randomly selecting more than 100 particles (primary particles) that cannot be further divided without overlapping or agglomerating. Extract and measure the major axis to obtain the average value. The content analysis is performed using both the ICP issue analysis method and the X-ray diffraction method.
(Preparation of polypropylene resin)
Trade name of Ciba Specialty Chemicals Co., Ltd. 0.1% by weight of CHIMASSORB 944LD and 0.2% by weight of Irganox 1425WL as a heat stabilizer to polypropylene resin powder polymerized using a Ziegler-Natta catalyst To t-butyl-P-cresol 0.05 wt% and calcium stearate 0.1 wt% mixed and melt extruded into chips,
The antibacterial agent particles listed in Table 1 were mixed and melt extruded to form chips.

(Melt blow spinning conditions)
(Relationship between melt blow spinning conditions and examples / comparative examples)
Mesh-spun air suction is applied to the above-mentioned polypropylene resin and fibers spun by applying the melt blow spinning conditions A to G (weight per unit of 12 g / m ² ) and I to J (weight per unit of 50 g / m ² ) described in Tables 1 and 2. A melt blown nonwoven fabric was prepared by collecting with a conveyor. In addition, the large and small display described in the row | line | column of the polymer discharge amount in the table | surface, polymer resin MFR, and an average fiber diameter has shown having used large or small as a nozzle hole. The description of one or three nozzle holes in the melt blow condition F indicates that three nozzle hole diameters are arranged between the nozzle hole diameters.

(Electretization method)
A hydrocharge method was used, in which pure water was sprayed onto the nonwoven fabric and completely wetted, then crushed with a nip roll, dehydrated to a moisture adhesion rate of 250%, and then dried in a dryer at 100 ° C. for 30 minutes.

Antibacterial agent particles (1): Silver sulfide particles having a primary particle size of 10 nm Antibacterial agent particles (2): Colloidal silica-impregnated silver sulfide particles having a primary particle size of 50 nm (silica weight ratio 60%)
Antibacterial agent particles (3): Silica-impregnated silver sulfide particles having a primary particle diameter of 180 nm (silica weight ratio 80%)
Antibacterial agent particles (4): Silica-impregnated silver sulfide particles having a primary particle diameter of 250 nm (silica weight ratio 80%).

(Examples 1-14)
About Table 3, the evaluation result of each antibacterial agent particle addition rate, fiber diameter / collection efficiency, antibacterial property (bacteriostatic activity value), antiviral inactivation rate, and antifungal property is shown. As the test results show, the antibacterial activity increases as the amount of silver sulfide particles increases due to the relationship between Examples 1, 2, 6, 10, 11, and 12, and as the fiber diameter decreases due to the relationship between Examples 4, 5, 6, and 9. You can see that the nature increases. In Example 13, a fiber group having an average fiber diameter of 1.2 μm (volume ratio 60%, fiber diameter range 0.1 to 6 μm) and a fiber group having an average fiber diameter 15 μm (volume ratio 40%, fiber diameter range 10 to 25 μm). ) Is an electret antibacterial meltblown nonwoven fabric having a mixed structure of different fineness with a pressure loss of 12 Pa and a collection efficiency of 93%. On the other hand, an electret antibacterial meltblown nonwoven fabric having an average fiber diameter of 1.7 μm and a pressure loss of 20 Pa was required to obtain the same collection efficiency of 93% with one fiber group. From this, it was confirmed that the mixed structure of different fineness was an antibacterial melt blown nonwoven fabric excellent in low pressure loss. In Example 14, a fiber group having an average fiber diameter of 0.5 μm (volume ratio 37.5%, fiber diameter range 0.05 to 0.1 μm) and a fiber group having an average fiber diameter of 15 μm (volume ratio 62.5%, This is an electret antibacterial meltblown nonwoven fabric having a mixed structure of different fineness with a pressure loss of 19 Pa and a collection efficiency of 99.8%, with two fiber diameter distributions in the fiber diameter range of 10 to 25 μm. Since the antibacterial property is higher than that of Example 13, the effect of the ultrafine fiber can also be confirmed.

(Example 15)
It is an electret antibacterial melt-blown nonwoven fabric with an average fiber diameter of 40 μm and a basis weight of 40 g / m ² , and contains 0.2% by weight of antibacterial particles in which silver sulfide is affixed to silica particles having a particle diameter of 180 nm, thereby providing high antibacterial properties. It was. As a result of pleating, it was found that the fiber diameter was the limit in terms of durability and practicality because cracks occurred in some fibers at the pleat apex.
(Example 16)
In the 6-step odor sensory evaluation using the samples of Example 7 and Comparative Example 1, the odor intensity of the sample of Example 7 was 2.8, whereas the odor intensity of the sample of Comparative Example 1 was 3.7, and the deodorizing effect Was confirmed.

(Example 17)
Nonwoven fabric processed with antibacterial, antiviral, and antiallergen (average fineness 5 dtex, basis weight 60 g / m ² , bacteriostatic activity value 5.4 or more, antiviral inactivation rate 99.9%, cedar pollen-free A filter unit (size W300 mm × L340 mm × D40 mm) containing 1.5 m ^{2 of the} filter medium was prepared using an antibacterial laminated fiber product laminated with an activation rate of 99.1% and a collection efficiency of 2% or less. Similarly, a non-functional nonwoven fabric (average fineness 5 dtex, basis weight 60 g / m ² , antibacterial property 0.1 or less, antiviral inactivation rate 0%, cedar pollen inactivation rate 0%, collection efficiency 2 % Or less) was prepared, and a filter unit (size W300 mm × L340 mm × D40 mm) containing 1.5 m ^{2 of the} filter medium was prepared. These two filters were installed in an air conditioner for an outside air intake in a general building and operated for 6 months, and an antifungal test was conducted on the cut filter media. As a result, the antifungal property of the comparative example was 3 (there was growth), and the antifungal property of Example 7 was 0 to 1 and some signs of growth were observed, but it was clearly confirmed that the antifungal property was excellent. It was.

(Comparative Example 1)
About Table 4, antibacterial property was not able to be confirmed in the comparative example 1 which does not contain an antibacterial agent particle.
(Comparative Example 2)
Since the fiber diameter was as large as 45 μm, the cooling was slow and spherulites developed and sufficient molecular orientation could not be obtained. In addition, the fiber was very brittle due to the high content of the antibacterial agent. When the pleating process is performed, fiber cutting frequently occurs at the bent portion and the entire loss may occur, which is impractical.

(Comparative Example 3)
Since the particle size was 250 nm and the antibacterial agent addition rate was large, nozzle clogging occurred frequently, and spinning could not be continued. It was found that the particle size of the antibacterial agent was too large to spin ultrafine fibers.

  Antibacterial meltblown nonwoven fabrics can be used particularly for masks, filters, wipers and the like. In particular, antibacterial appeal products that have been used for masks and filters in the past were non-antibacterial ultrafine fiber nonwoven fabrics laminated with antibacterial very thick nonwoven fabrics. . However, by changing the non-antibacterial ultrafine fiber nonwoven fabric to the antibacterial meltblown nonwoven fabric of the present invention, inactivation of bacteria and viruses is promoted, so that the risk level of infection can be lowered by one layer, so the use is expanded To do.

Claims (7)

An antibacterial meltblown nonwoven fabric having an average fiber diameter of 40 μm or less including antibacterial particles having a primary particle diameter of less than 200 nm. The antibacterial meltblown nonwoven fabric according to claim 1, wherein the antibacterial agent particles are silver sulfide particles and / or silica-added silver sulfide particles. The antibacterial melt blown nonwoven fabric according to claim 1 or 2, wherein a plurality of fiber groups having different antibacterial agent content are mixed. The antibacterial meltblown nonwoven fabric according to any one of claims 1 to 3, wherein the antibacterial meltblown nonwoven fabric has a plurality of fiber groups having different average fiber diameters, of which the fiber group having an average fiber diameter of 6 µm or more occupies 20% or more of the total fiber volume. . The antibacterial meltblown nonwoven fabric according to any one of claims 1 to 4, which is electretized. A filter using the antibacterial meltblown nonwoven fabric according to any one of claims 1 to 5. The filtration apparatus using the antibacterial melt blown nonwoven fabric in any one of Claims 1-5.