JP6546336B2 - Nonwoven fabric, filter and method of manufacturing nonwoven fabric - Google Patents

Description

  The present invention relates to a nonwoven fabric, a filter and a method of manufacturing the nonwoven fabric.

Non-woven fabrics, especially spun-bonded non-woven fabrics and melt-blown non-woven fabrics have the advantage of being free from the possibility of mixing of impurities since they do not use binders for fiber accumulation, and having excellent chemical resistance by selecting the type of fibers. It is used for various applications.
Among them, melt-blown non-woven fabrics (also referred to as “melt-blown non-woven fabrics”) are superior in flexibility, uniformity, and compactness because they can be formed of ultrafine fibers as compared with spun-bonded non-woven fabrics. For this reason, the meltblown non-woven fabric is laminated alone or with other non-woven fabric etc, and the filter (filter for liquid, filter for gas, etc.), sanitary material, medical material, agricultural coating material, civil engineering material, building material, oil adsorption It is widely used for materials, automobile materials, electronic materials, separators, clothing, packaging materials, etc.

When meltblown nonwovens are used for filters, the thinner the fibers of the nonwoven, the higher the ability to separate fine materials.
Therefore, as a method of thinning the fibers constituting the non-woven fabric and obtaining a polyethylene non-woven fabric of fine fibers, there has been proposed a method of molding a resin composition containing polyethylene and polyethylene wax by the melt-blowing method (for example, patent documents 1).
However, when a non-woven fabric made of small diameter fibers is used as a filter, the filter is easily compressed by the pressure of the fluid, and if it is compressed, the filtration flow rate decreases or the pore diameter of the opening changes and the design value It may be difficult to achieve the same fine particle rejection rate.
For this reason, for example, a resin composition containing polyethylene and polyethylene wax is molded by a melt-blowing method, and a melt-blown nonwoven fabric which is a molded product obtained is a spun bond comprising composite fibers formed of polyester and ethylene polymer. A method of laminating a non-woven fabric and using it as a filter has been proposed (see, for example, Patent Document 2).

Furthermore, from the viewpoint of the fiber diameter, a melt-blown nonwoven fabric using a nozzle piece of a specific shape is proposed to obtain a single melt-blown nonwoven fabric having a wide fiber diameter distribution simultaneously formed integrally as fibers for a filter. (See, for example, Patent Document 3). By using the said nozzle piece, it is described that the nonwoven fabric which consists of a fine fiber with a fiber diameter of 1 micrometer-10 micrometers and a wide fiber diameter dispersion | distribution will be obtained.
Further, as a filter excellent in the balance between the filtration flow rate and the fine particle rejection, a filter made of a polyethylene non-woven fabric formed by melt-blowing a resin composition containing polyethylene of a specific molecular weight and polyethylene wax has been proposed See, for example, Patent Document 4).
Patent Document 1: International Publication No. 2000/22219 Patent Document 2: International Publication No. 2012/111724 Patent Document 3: JP-A-11-131353 Publication Patent Document 4: International Publication No. 2015/93451

The above-mentioned Patent Document 1 discloses that a melt-blown polyethylene non-woven fabric having a fiber diameter of 2.8 μm can be obtained by molding a resin composition containing a specific polyethylene and a polyethylene wax by a melt-blowing method (Patent Document 1) See Example 2 of 1). Patent Document 2 mentioned above discloses that a melt-blown polyethylene non-woven fabric having a fiber diameter of 3.3 μm can be obtained.
Moreover, although the dispersion of the fiber diameter which comprises the nonwoven fabric of the nonwoven fabric of the above-mentioned patent document 3 is wide, the median of the fiber diameter in an Example is 5.5 micrometers-7.0 micrometers, and all are based on a fine fiber It is difficult to obtain a non-woven fabric having fine voids.
In the non-woven fabric described in Patent Document 4 mentioned above, a thinner fiber diameter is achieved, but in consideration of the case where the non-woven fabric is used alone as a filter, it is required to make the fine particle rejection rate better.

The present invention has been made in view of the above-mentioned circumstances, and an object of one embodiment of the present invention is a non-woven fabric which can be suitably used for a filter application, which has a large surface area and has fine voids. To provide a filter that includes
An object of another embodiment of the present invention is to provide a method for producing a non-woven fabric having a large surface area and a high fine particle rejection when used in a filter.

Means for solving the problems include the following embodiments.
<1> A nonwoven fabric containing thermoplastic resin fibers having an average fiber diameter of 5 μm or less and a fiber diameter integrated frequency of 100 nm to 200 nm of 3.0% or more.
<2> The nonwoven fabric according to <1>, in which the ratio of the peak fiber diameter to the average fiber diameter is 0.5 or less.
The nonwoven fabric as described in <1> or <2> whose viscosity measured by making it melt | dissolve at <3> 200 degreeC is 0.1 Pa.s-100.0 Pa.s.

The nonwoven fabric as described in any one of <1>-<3> in which the <4> above-mentioned thermoplastic resin fiber contains a wax.
<5> The nonwoven fabric according to <4>, wherein the thermoplastic resin fiber contains the wax in an amount of 10% by mass to 60% by mass with respect to the total amount of the thermoplastic resin fiber.
The nonwoven fabric as described in any one of <1>-<5> whose peak fiber diameter of the <6> above-mentioned thermoplastic resin fiber is 1 micrometer or less.
The nonwoven fabric as described in any one of <1>-<6> whose thermoplastic resin in <7> said thermoplastic resin fiber is a homopolymer or copolymer of alpha-olefin.
<8> The nonwoven fabric according to any one of <1> to <7>, wherein the thermoplastic resin in the thermoplastic resin fiber is a polymer containing a structural unit derived from propylene.

The filter containing the nonwoven fabric as described in any one of <9> <1>-<8>.

A thermoplastic resin composition containing a <10> thermoplastic resin and having a melt viscosity at 200 ° C. of 0.1 Pa · s to 100.0 Pa · s is melted, and 10 ⁻⁹ m ³ to 10 ⁻⁴ m from a spinning nozzle ^{And (3} ) supplying the gas to the dropped molten resin mass to form thermoplastic resin fibers, and accumulating the formed thermoplastic resin fibers. The manufacturing method of the nonwoven fabric as described in any one of <1>-<8>.

  According to one embodiment of the present invention, there is provided a non-woven fabric that can be suitably used for a filter application, having a large surface area and having fine voids, and a filter comprising the non-woven fabric. Moreover, according to another embodiment of the present invention, there is provided a method for producing a non-woven fabric having a large surface area and having a high fine particle rejection when used for a filter.

It is a graph which shows logarithmic frequency distribution of the fiber diameter in the nonwoven fabric of Examples 1-3 and Comparative Examples 1 and 2. It is the schematic perspective view which looked at the die for melt-blowing of the melt-blown nonwoven fabric manufacturing apparatus used in the Example of this invention from the lower surface side.

  The numerical range shown using "-" in this specification shows the range included as the minimum value and the maximum value which are described before and after "-", respectively.

<Non-woven fabric>
The nonwoven fabric of the present embodiment includes thermoplastic resin fibers having an average fiber diameter of 5 μm or less and a fiber diameter integrated frequency of 100 nm to 200 nm of 3.0% or more.
In the nonwoven fabric of the present embodiment, the fibers containing a thermoplastic resin (thermoplastic resin fibers) have an average fiber diameter of 5 μm or less, and a part of the thermoplastic resin fibers has a fiber diameter of 100 nm to 200 nm, The fiber diameter integrated frequency of 100 nm to 200 nm is present at a rate of 3.0% or more. As a result, portions having a fine fiber diameter exist as the non-woven fabric, and due to the presence of the fine fibers, fine voids are generated in the non-woven fabric, and the surface area of the non-woven fabric becomes large. Therefore, when the nonwoven fabric of the present embodiment is used for a filter, the fine particle rejection rate becomes good due to the presence of fine fibers.

Moreover, as for the thermoplastic resin fiber contained in the nonwoven fabric of this embodiment, it is preferable that the ratio of the peak fiber diameter with respect to an average fiber diameter is 0.5 or less. According to a preferable aspect of the present embodiment, in the fiber diameter distribution of the non-woven fabric, the fiber diameter distribution is wide, fibers of extremely small diameter are present, and the ratio of the peak fiber diameter to the average fiber diameter is 0.5 or less Since the peak fiber diameter, which is the mode value, is smaller than the average fiber diameter, the presence of fibers having a fiber diameter larger than the average fiber diameter further improves the resistance to non-woven fabric compression.
When a non-woven fabric using a thermoplastic resin fiber having a ratio of a peak fiber diameter to an average fiber diameter of 0.5 or less, which is a preferable aspect of the present embodiment, is used for a filter, fine particles can be prevented due to the fine fiber diameter. The rate is better, and the resistance to compression is improved due to the larger fiber diameter, and the performance of the filter is maintained for a longer time. In particular, the non-woven fabric, which is a preferable aspect of the present embodiment, can be expected to be applied to a separation filter such as gel particles which are easily clogged with a filter and difficult to use for a long time to exhibit high performance.

In general, when a thermoplastic resin is used to form a meltblown non-woven fabric, molten thermoplastic resin is continuously supplied from a nozzle for forming fibers, and fibers are formed by blowing hot air. In this case, the fiber diameter of the thermoplastic resin fiber to be formed depends on the diameter of the nozzle of the nozzle for discharging the thermoplastic resin and the viscosity of the molten thermoplastic resin.
However, in the prior art, there are machining limitations to make the nozzle diameter smaller for the purpose of forming fine fibers.
On the other hand, when taking measures to lower the melt viscosity of the thermoplastic resin in order to reduce the fiber diameter, deterioration of the resin may occur when the heating temperature is raised, or the melt viscosity is too low. The continuous and uniform discharge may be difficult.
In contrast to the prior art, the nonwoven fabric of the present embodiment is excellent in the balance between the extremely thin fiber diameter and the thicker fiber because the fiber diameter of the thermoplastic resin fiber has a specific condition distribution, As a result, in spite of having a large surface area, resistance to compression as a whole of the nonwoven fabric is good.

As a physical property of the nonwoven fabric of this embodiment, it is preferable that the viscosity which melt | melted the nonwoven fabric at 200 degreeC and measured it is 0.1 Pa.s-100.0 Pa.s, 0.1 Pa.s-50.0 Pa.s The pressure is more preferably 0.5 Pa · s to 10.5 Pa · s, further preferably 1.0 Pa · s to 10 Pa · s.
When the viscosity measured by melting the nonwoven fabric at 200 ° C. is within the range described above, it is possible to more easily obtain a thermoplastic resin fiber having a fiber diameter distribution suitable for the nonwoven fabric of the present embodiment.

It is preferable that the thermoplastic resin fiber which forms the nonwoven fabric of this embodiment contains a wax.
By including a wax in the thermoplastic resin fiber, in the thermoplastic resin fiber, it is possible to more easily achieve a fiber shape having a fine fiber diameter specified in the present embodiment and a specific fiber diameter distribution.
When the thermoplastic resin fiber contains a wax, it can be confirmed that the thermoplastic resin composition forming the fiber contains a wax.
When the thermoplastic resin composition used to form the fiber contains a wax, the viscosity of the thermoplastic resin composition in a molten state at the time of fiber formation can be easily adjusted to the above-described preferable range, and this embodiment is defined in this embodiment. Thermoplastic resin fibers having the following fiber diameter distribution can be efficiently obtained.

The thermoplastic resin fiber preferably contains a wax in an amount of 10% by mass to 60% by mass with respect to the total amount of the thermoplastic resin fiber.
The content of the wax is more preferably in the range of 20% by mass to 50% by mass, and still more preferably in the range of 30% by mass to 40% by mass.

  It is preferable that the nonwoven fabric of this embodiment does not contain a solvent component. A non-woven fabric not containing a solvent component can be obtained by melting the thermoplastic resin composition and intermittently dropping it as a molten resin mass from a spinning nozzle as described in the preferred non-woven fabric manufacturing method of the present embodiment described later. it can. The solvent component means an organic solvent component capable of dissolving the resin in the fiber. Examples of the solvent component include dimethylformamide (DMF) and the like. In the present specification, the non-woven fabric does not contain a solvent component means that the content of the solvent component when the non-woven fabric is analyzed by head space gas chromatography is equal to or less than the detection limit of the measuring device.

Next, the fiber shape of the non-woven fabric of the present embodiment will be described in detail.
The nonwoven fabric of the present embodiment is a thermoplastic resin fiber having an average fiber diameter of 5 μm or less, and includes a thermoplastic resin fiber in which a fiber diameter integrated frequency of 100 nm to 200 nm is 3.0% or more.
Moreover, it is preferable that the ratio of the peak fiber diameter with respect to an average fiber diameter of the thermoplastic resin fiber contained in a nonwoven fabric is 0.5 or less.
Here, the average fiber diameter and the peak fiber diameter of the thermoplastic resin fiber will be described. The fiber diameter of the thermoplastic resin fiber contained in the nonwoven fabric of this embodiment is measured by the following method.

(1) Measurement of average fiber diameter A non-woven fabric is photographed at a magnification of 5000 times using an electron microscope "S-3500N" manufactured by Hitachi Ltd., and the fiber width (diameter: μm) is randomly measured at 1000 points The average fiber diameter (μm) was calculated by averaging the number averages.
In order to randomize the measurement points of the fibers in the non-woven fabric, a diagonal was drawn from the upper left corner to the lower right corner of the photographed photograph, and the width (diameter) of the fibers at the intersection of the diagonal and the fibers was measured. A new photograph was taken and measured until the number of measurement points reached 1000.

(2) Peak fiber diameter (moderate fiber diameter)
The logarithmic frequency distribution was created based on the data of the fiber diameter (μm) of 1000 points measured by the above-mentioned “(1) Measurement method of average fiber diameter”.
The logarithmic frequency distribution is plotted on a logarithmic scale with the x-axis as fiber diameter (μm) on the base of 10, and the y-axis is a percentage of the frequency. On the x-axis, the fiber diameter from 0.1 (= 10 ^-1 ) μm to the fiber diameter 50.1 (= 10 ^1.7 ) μm is equally divided into 27 on a logarithmic scale, and the frequency is highest The value of the geometric average of the minimum value and the maximum value of the x axis in the divided section was taken as the peak fiber diameter (the mode fiber diameter, the first peak fiber diameter described later).

  In the thermoplastic resin fiber contained in the nonwoven fabric of the present embodiment, the average fiber diameter is not particularly limited as long as it is 5 μm or less, for example, preferably 1 μm to 5 μm, and 1.5 μm to 4.0 μm. More preferably, the thickness is 2.0 μm to 3.5 μm.

  In the thermoplastic resin fiber contained in the nonwoven fabric of the present embodiment, the ratio of the peak fiber diameter to the average fiber diameter is preferably 0.5 or less. That is, when the obtained average fiber diameter is 1, the peak fiber diameter is 0.5 or less, and the peak fiber diameter is thinner than the average fiber diameter, so that the nonwoven fabric of the present embodiment has a large surface area. When a non-woven fabric is used as a filter, a filter having a fine particle rejection rate becomes good. Furthermore, the ratio of the peak fiber diameter to the average fiber diameter is more preferably 0.45 or less, still more preferably 0.4 or less, particularly preferably 0.05 to 0.3, and 0 More preferably, it is .05-0.2.

The peak fiber diameter of the thermoplastic resin fiber is preferably thinner than the average fiber diameter, more specifically, preferably 1 μm or less, and more preferably in the range of 0.05 μm to 0.6 μm, More preferably, it is in the range of 0.05 μm to 0.4 μm.
When the peak fiber diameter is 1 μm or less, the surface area of the obtained non-woven fabric becomes larger, and the fine particle rejection rate becomes higher when the non-woven fabric is used for a filter.

(3) Fiber diameter integrated frequency of 100 nm to 200 nm In the data of the fiber diameter (μm) of 1000 points measured by the above-mentioned “(1) Method of measuring average fiber diameter”, the number of total fiber diameters is measured. The number of locations where the fiber diameter is 100 nm to 200 nm was measured, and the fiber diameter integration frequency was calculated as a percentage.

In the fiber diameter of the thermoplastic resin fiber contained in the nonwoven fabric of this embodiment, the fiber diameter integrated frequency of 100 nm-200 nm exists 3.0% or more. The fiber diameter integrated frequency of 100 nm to 200 nm is preferably 3.0% to 50%, more preferably 4.0% to 40%, still more preferably 5.0% to 40% And most preferably 10.0% to 30%.
When the fiber diameter integrated frequency of 100 nm to 200 nm is 3.0% or more, the existence ratio of fine fibers becomes an effective amount, the surface area of the obtained nonwoven fabric becomes sufficiently large, and the nonwoven fabric is used as a filter, The fine particle rejection rate is good.

The shape of the thermoplastic resin fiber will be described in more detail.
As described above, the thermoplastic resin fibers contained in the nonwoven fabric of the present embodiment have an average fiber diameter of 5 μm or less, and a condition that a fiber diameter integrated frequency of 100 nm to 200 nm is 3.0% or more. Fulfill.
These conditions show that the average fiber diameter of the thermoplastic resin fiber contained in a nonwoven fabric is thin. Also, it shows that it has a very fine fiber diameter of 200 nm or less.
The thermoplastic resin fibers preferably have a ratio of the peak fiber diameter to the average fiber diameter of 0.5 or less. When the ratio of the peak fiber diameter is 0.5 or less, the thermoplastic resin fiber further contained in the non-woven fabric which is a preferable aspect of the present embodiment has a fiber diameter larger than the average fiber diameter to some extent. It shows that it has a fiber diameter distribution.
As a preferable fiber diameter distribution, when logarithmic frequency distribution is created based on data of fiber diameter, it has a peak fiber diameter of 0.5 or less of the average fiber diameter (hereinafter also referred to as first peak fiber diameter), It is preferable to have a second peak fiber diameter in a region of a fiber diameter larger than the average fiber diameter. Having a second peak fiber diameter in a region of a fiber diameter larger than the average fiber diameter indicates that a fiber having a fiber diameter larger than the average fiber diameter is present at a certain frequency, and the average fiber diameter in the nonwoven fabric Having thick fibers with a certain degree of frequency makes the nonwoven more resistant to compression.
The second peak fiber diameter means the most frequent fiber diameter in the region of the fiber diameter larger than the average fiber diameter when the first peak fiber diameter exists in the logarithmic frequency distribution created based on the fiber diameter data. Say.

Hereinafter, the material of the thermoplastic resin fiber contained in the nonwoven fabric of this embodiment is demonstrated.
(Thermoplastic resin)
The thermoplastic resin used for the production of the nonwoven fabric of the present embodiment is not particularly limited as long as it is a thermoplastic resin applicable to the production of a melt-blown nonwoven fabric, and a known thermoplastic resin can be used.
Specific examples of thermoplastic resins applicable to the present embodiment include homopolymers of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. Or a copolymer is mentioned.
As a homopolymer or copolymer of α-olefin, high pressure low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), ethylene / propylene random copolymer, ethylene / 1 -Homopolymer of ethylene such as butene random copolymer or ethylene-containing copolymer such as ethylene / α-olefin copolymer; homopolymer of propylene (polypropylene: PP), propylene / ethylene random copolymer, propylene / Propylene-containing polymers such as ethylene / 1-butene random copolymer (random polypropylene), propylene block copolymer, propylene / 1-butene random copolymer; 1-butene homopolymer, 1-butene / ethylene copolymer Polymer, 1-butene such as 1-butene / propylene copolymer Copolymers containing 4-methyl-1-pentene homopolymer, 4-methyl-1-pentene / propylene copolymer, 4-methyl-1-pentene / α-olefin copolymer, etc. Α-olefin-containing polymers such as 1-pentene-containing copolymers; and the like.

  Examples of thermoplastic resins other than α-olefin-containing polymers include polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon-6, nylon-66 and polymetaxylene adipamide; polyvinyl chloride; Examples thereof include polyimides; ethylene / vinyl acetate copolymers; polyacrylonitriles; polycarbonates; polystyrenes; ionomers and mixtures thereof.

  Among these thermoplastic resins, α-olefin-containing polymers are preferred from the viewpoints of spinning stability during molding, processability and air permeability of nonwoven fabrics, flexibility, lightness and heat resistance. Among the α-olefin-containing polymers, a polymer containing a structural unit derived from propylene (hereinafter sometimes referred to as a propylene-based polymer) is preferable from the viewpoint of heat resistance and lightness. That is, the thermoplastic resin in the thermoplastic resin fiber is preferably a polymer containing a structural unit derived from propylene. As the propylene-based polymer, a propylene homopolymer, a copolymer of propylene and an α-olefin other than propylene, and the like are more preferable.

-Propylene-based polymer In the present embodiment, a propylene-based polymer suitable as a thermoplastic resin is usually a propylene homopolymer having a melting point (Tm) of 125 ° C. or higher, preferably in the range of 130 to 165 ° C. Or propylene and a very small amount of ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. The copolymer of 1 type, or 2 or more types can be mentioned. As a copolymer containing a structural unit derived from propylene, a copolymer of propylene and one or more kinds of α-olefins selected from α-olefins having 2 or 4 to 8 carbon atoms is more preferable. preferable. The type is not particularly limited as long as it is a propylene-based polymer satisfying the melt viscosity.

The melt flow rate (MFR: ASTM D1238, 230 ° C., load 2.16 kg) is not particularly limited as long as melt-spinning is possible for the propylene-based polymer. From the viewpoint of spinnability, the MFR is preferably 10 g / 10 min to 4000 g / 10 min, more preferably 50 g / 10 min to 3000 g / 10 min, and 100 g / 10 min to 2000 g / 10 min. More preferably, it is in the range of
In addition, MFR in this specification uses the value measured by the temperature of 230 degreeC, and 2.16 kg of loads based on ASTMD1238.

(Thermoplastic resin composition)
The thermoplastic resin fiber contained in the nonwoven fabric of the present embodiment may be formed only from the above-mentioned thermoplastic resin, but in addition to the thermoplastic resin, a known thermoplastic resin can be used as long as the effects of the present embodiment are not impaired. You may form from the thermoplastic resin composition which further contains an additive other than.
Additives which the thermoplastic resin composition may contain include waxes, crystal nucleating agents, stabilizers such as heat resistant stabilizers, weather resistant stabilizers, fillers, antistatic agents, hydrophilic agents, water repellents, anti blocking agents, Examples thereof include a fogging agent, a lubricant, a coloring agent such as a dye and a pigment, a natural oil, a synthetic oil and the like.
The thermoplastic resin composition may contain only one type of other additive, or may contain two or more types.

(wax)
The thermoplastic resin composition preferably contains a wax as described above.
As the wax, any wax that can be used for fiber modification can be used without particular limitation. Among them, a wax having an affinity to a thermoplastic resin is preferable.
For example, in the case of using a propylene-based polymer as the thermoplastic resin, it is preferable to include a propylene-based wax. When the thermoplastic resin composition contains a propylene-based polymer and a propylene-based wax, it becomes easier to reduce the average fiber diameter of the obtained nonwoven fabric, and it is easier to obtain a nonwoven fabric of uniform quality. Become.

  The propylene-based wax is a propylene-based polymer having a relatively low molecular weight, that is, a wax-like propylene-based polymer. The production method of the propylene-based wax is not particularly limited. The propylene-based wax may be one produced by polymerization of a low molecular weight polymer or monomer generally used, or one obtained by thermally decomposing a higher molecular weight propylene-based polymer to reduce the molecular weight. Good.

The weight average molecular weight (Mw) of the propylene-based wax that can be used in the present embodiment is preferably 22,000 or less. The Mw of the propylene-based polymer wax (b) is preferably 400 to 20,000, more preferably 400 to 15,000, still more preferably 2,000 to 14,000, and particularly preferably 6 And 13,000 to 13,000.
The measurement of the molecular weight and molecular weight distribution of the wax is performed using GPC. The measurement is performed under the following conditions, using a commercially available monodispersed standard polystyrene as a standard.
Device: Gel permeation chromatography Alliance GPC2000 (manufactured by Waters)
Solvent: o-dichlorobenzene Column: TSKgel column (made by Tosoh Corporation) x 4
Flow rate: 1.0 ml / min Sample: 0.3% o-dichlorobenzene solution temperature: 140 ° C.
When the Mw of the propylene-based wax is in the above range, the thermoplastic resin fibers contained in the non-woven fabric can be easily made thinner. In addition, when Mw is in the above range, it is possible to more reliably suppress the temporal bleed out of the wax from the organic resin fiber.

The propylene-based wax preferably has a softening point of greater than 90 ° C. as measured according to JIS K 2207 (1996). The softening point is more preferably 100 ° C. or more.
The heat resistance stability at the time of heat processing or use can be improved more as a said softening point is 90 degreeC or more, and as a result, the heat resistance of a nonwoven fabric can be improved more.
Although the upper limit in particular of the said softening point is not restrict | limited, For example, 168 degreeC is mentioned as an upper limit.

Examples of the propylene-based wax include homopolymers of propylene and copolymers of propylene and an α-olefin having 2 or 4 to 20 carbon atoms.
Among them, the thermoplastic resin composition contains a propylene-based polymer and a propylene-based wax, and the propylene-based wax is a homopolymer of propylene, and the kneadability of the propylene-based polymer and the propylene-based wax It is preferable because a more uniform and more uniform thermoplastic resin composition is formed.

Although density measured is not particularly limited according to the propylene-based wax JIS K6760 (1995 years), preferably for example ^{0.890g / cm 3 ~0.980g / cm 3} , 0.890g / cm 3 more preferably ~0.960g / cm ^3, and even more preferably from ^{0.900g / cm 3 ~0.960g / cm 3} , a 0.900g / cm ³ ~0.950g / cm 3 Is particularly preferred.
When the propylene-based wax density is in the above range, the kneadability of the propylene-based wax and the propylene-based polymer is more excellent, and the spinnability and the stability over time become more excellent.

The propylene-based wax may be a commercially available product. Examples of commercially available products include Hi Wax (registered trademark) NP series manufactured by Mitsui Chemicals, Inc., and the like.
The thermoplastic resin composition may contain only one type of propylene-based wax, or may contain two or more types.
The content of the propylene-based wax relative to the total amount of the thermoplastic resin composition is preferably in the range of 10% by mass to 60% by mass, more preferably in the range of 15% by mass to 55% by mass, and 20% by mass to 50% by mass. The range of% is more preferable, and the range of 30% by mass to 40% by mass is particularly preferable.
When the content of the propylene-based wax with respect to the total amount of the thermoplastic resin composition is in the above-mentioned range, the spinnability becomes better, and the peak fiber diameter can be further narrowed.

  From the viewpoint of effect, the total content of the propylene-based polymer and the propylene-based wax in the thermoplastic resin composition is preferably 80% by mass or more, and more preferably 90% by mass or more.

(Crystal nucleating agent)
The thermoplastic resin composition can include a crystal nucleating agent. As the crystal nucleating agent, one that can be a nucleus at the time of crystallization of the thermoplastic resin can be used without limitation.
The crystal nucleating agent used in the present embodiment is an additive that generates nucleation sites at the time of crystallization of the thermoplastic resin in a transition state in which the molten state of the thermoplastic resin changes to a solid state by being cooled. Means The crystal nucleating agent may be used alone or in combination of two or more.
0.01 mass part-10 mass parts are preferable with respect to 100 mass parts of thermoplastic resin compositions, as for content of a crystal nucleating agent, 0.03 mass part-3 mass parts are more preferable, and 0.03 mass part -0.5 mass part is further more preferable.

(Stabilizer)
As the stabilizer, for example, an antioxidant such as 2,6-di-t-butyl-4-methyl-phenol (BHT); tetrakis [methylene-3- (3,5-di-t-butyl-4-4) Hydroxyphenyl) propionate] methane, β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid alkyl ester, 2,2′-oxamide bis [ethyl-3- (3,5-di-t-) Phenolic antioxidants such as butyl-4-hydroxyphenyl) propionate], Irganox 1010 (hindered phenolic antioxidant: trade name), etc .; Fatty acid metals such as zinc stearate, calcium stearate, and 1,2-hydroxystearate Salts; glycerin monostearate, glycerin distearate, pentaerythritol monosteare Polyhydric alcohol fatty acid esters such as H., pentaerythritol distearate and pentaerythritol tristearate; and the like.

(Filling material)
As the filler, silica, kieselguhr, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, Calcium sulfite, talc, clay, mica, asbestos, calcium silicate, montmorillonite, pentonite, graphite, aluminum powder, molybdenum sulfide, carbon nanotubes (CNT), cellulose nanofibers and the like can be mentioned.

  There are no particular limitations on the method of preparing the thermoplastic resin composition. As a method of preparing a thermoplastic resin composition, for example, a method of mixing a propylene-based polymer, if desired, with a propylene-based wax which is a preferable additive, and the above-mentioned other additives using various known methods It can be mentioned.

(Physical properties of non-woven fabric)
The preferable physical properties other than the fiber diameter of the nonwoven fabric obtained by using the thermoplastic resin composition as stated above are demonstrated.

(1. Weight)
There is no restriction | limiting in particular in the fabric weight of the nonwoven fabric of this embodiment, According to the intended purpose of a nonwoven fabric, it can set suitably.
Basis weight when using nonwoven fabric of the present embodiment the filter is preferably 0.5 g / ^{m 2} or more, more preferably ^{0.5g / m 2 ~50g / m 2} , more preferably 1 g / m a ^{2 ~40g} / ^{m 2,} particularly preferably from ^{1g / m 2 ~20g / m 2} .
Within the above-mentioned range, the strength of the non-woven fabric is further improved in the above-described range of the non-woven fabric, and fine diameter fibers are more easily obtained. Furthermore, the layer weight of the non-woven fabric in use can be adjusted by laminating the non-woven fabric of the above-mentioned weight.

On the other hand, when used in applications where high barrier properties are not so much required, such as sanitary materials applications, and where flexibility, heat sealing properties, lightweight properties, etc. are required, the fabric weight of the nonwoven fabric is, for example, 0.5 g / m ² it is preferable that a to 5 g / ^{m 2,} more preferably from ^{0.5g / m 2 ~3g / m 2} .

(2. Maximum pore size)
The nonwoven fabric of the present embodiment has a maximum pore size measured at a basis weight of 60 g / m ² , preferably 30 μm or less, more preferably 20 μm or less, and still more preferably 15 μm or less.

(3. Average pore size)
The polyethylene nonwoven fabric in the present embodiment has an average pore diameter measured at a basis weight of 60 g / m ² , preferably 20 μm or less, more preferably 15 μm or less, and still more preferably 10 μm or less.
The lower limit of the average pore size is not particularly limited, but in the case of using a non-woven fabric as a filter, the average pore size is preferably 0.5 μm or more, more preferably 0.8 μm from the viewpoint of further improving the filtration flow rate. It is above.

The maximum pore size and the average pore size of the non-woven fabric can be measured by the method described below.
It adjusts so that it may become 60 g / m < ² > of fabric weight by laminating | stacking a nonwoven fabric, A test piece is extract | collected from the nonwoven fabric laminated body after adjustment.
The collected test pieces are immersed in a fluorine-based inert liquid (trade name: Florinert manufactured by 3M) in a temperature-controlled room with a temperature of 20 ± 2 ° C. and a humidity of 65 ± 2%, as defined in JIS Z 8703 (standard state of test place) The maximum pore size (μm) and the average pore size (μm) of the test pieces are measured using Capillary Flow Porometer "Model: CFP-1200AE" manufactured by Porous materials, Inc.

(4. air permeability)
The nonwoven fabric of the present embodiment preferably has a permeability of 15 cm ³ / cm ² / sec or less measured at a basis weight of 60 g / m ² . Non-woven fabrics having an air permeability of 15 cm ³ / cm ² / sec or less can have a smaller average pore diameter by containing fibers of an extremely fine diameter in an appropriate amount. For this reason, when the nonwoven fabric of this embodiment is used for a filter, there exists a tendency for a fine particle rejection to become large.
The air permeability is preferably 0.1 cm ³ / cm ² / sec or more, and more preferably 1 cm ³ / cm ² / sec or more. Nonwoven fabrics having an air permeability of 0.1 cm ³ / cm ² / sec or more can increase the treatment flow rate when used in a filter.

<Method of manufacturing non-woven fabric>
The nonwoven fabric of this embodiment as stated above can be efficiently manufactured by the manufacturing method of the nonwoven fabric described below.
The method for producing the non-woven fabric of the present embodiment melts a thermoplastic resin composition containing a thermoplastic resin and having a melt viscosity at 200 ° C. of 0.1 Pa · s to 100.0 Pa · s, and 10 ⁻⁹ from a spinning nozzle. Allowing the molten resin mass to drop intermittently as m ³ to 10 ^-4 m ³ (hereinafter sometimes referred to as a resin dropping step), a gas is supplied to the dropped molten resin mass to form a thermoplastic resin fiber (Hereinafter, may be referred to as a fiber forming step), and accumulating the formed thermoplastic resin fibers (hereinafter, may be referred to as a fiber accumulation step).
The "molten resin mass" in the present specification refers to a single molten resin droplet when the molten thermoplastic resin composition is intermittently dropped from the spinning nozzle in the form of droplets.
Further, in the present specification, "discontinuously dropping as a molten resin mass" indicates that droplets of the molten resin are dropped from the spinning nozzle at a constant or indefinite interval.

(manufacturing device)
The nonwoven fabric of this embodiment can be manufactured using the already-mentioned thermoplastic resin composition using the manufacturing apparatus of a well-known melt-blown nonwoven fabric.
Specifically, the melt-blown nonwoven fabric manufacturing apparatus includes an extruder for melt-kneading a thermoplastic resin composition, a spinning nozzle for dropping a melt-kneaded resin composition, and a resin composition dropped from the spinning nozzle. A gas supply device for forming a resin composition into a fibrous form by injecting a high-speed and high-temperature gas from the surroundings, and an accumulation device for depositing the obtained thermoplastic resin fibers to a predetermined thickness on a collection belt Any known melt-blown nonwoven fabric manufacturing apparatus can be applied to the manufacturing method of the present embodiment.
In addition, the nonwoven fabric manufacturing apparatus which improved so that it might be suitable by the manufacturing method of this embodiment to the melt-blown nonwoven fabric manufacturing apparatus of a well-known, for example, thermoplasticity so that it may be suitable for supply conditions of the thermoplastic resin composition explained in full detail below. Manufacture of the present invention is a non-woven fabric device using an improvement such as using a melt-kneading apparatus having a viscosity adjusting function of a resin composition, changing the shape of a spinning nozzle, or smoothing the inner surface of the nozzle. It goes without saying that it can be used for the method.

(1. Resin dropping process)
In the manufacturing method of the present embodiment, first, a thermoplastic resin composition is melted, and the thermoplastic resin composition having a melt viscosity at 200 ° C. of 0.1 Pa · s to 100.0 Pa · s is melted and 10 ⁻⁹ from a spinning nozzle. The molten resin mass is dropped intermittently as m ³ to 10 ^-4 m ³ . At this time, the molten resin mass is intermittently dropped from the spinning nozzle while maintaining the temperature of the thermoplastic resin of the thermoplastic resin composition at around 200 ° C.
As a method of adjusting the viscosity at 200 ° C. of the thermoplastic resin composition to 0.1 Pa · s to 100.0 Pa · s, for example, the thermoplastic resin contained in the thermoplastic resin composition, preferably a propylene-based polymer Method of selecting molecular weight, method of incorporating wax, lubricant and the like into thermoplastic resin composition, temperature and shear force of melt extrusion apparatus for kneading thermoplastic resin composition to control propylene weight in melt extruding apparatus A method of lowering the molecular weight of coalescence, and the like can be mentioned.

  The viscosity of the thermoplastic resin composition at 200 ° C. is in accordance with JIS K 7199 (1999), using a capillary rheometer (Capillograph 1D manufactured by Toyo Seiki Seisakusho Co., Ltd. and capillary with a tube length of 15 mm and a tube diameter of 0.5 mm). The piston speed can be measured as 5 mm / min.

Among them, from the viewpoint of further improving the spinnability, a method of incorporating a wax in the thermoplastic resin composition is preferable as a method of adjusting the viscosity of the thermoplastic resin composition at 200 ° C. In the case of using a wax, it is preferable to select a wax which has a good affinity to the thermoplastic resin used for spinning and which is easy to melt and knead uniformly.
As a suitable aspect of this embodiment, combined use of a propylene polymer and a propylene wax is mentioned. As described above, the content of the propylene-based wax in the thermoplastic resin composition is preferably in the range of 10% by mass to 60% by mass with respect to the total amount of the thermoplastic resin composition, and 15% by mass to 55% by mass. The range of% is more preferable, the range of 20% by mass to 50% by mass is further preferable, and the range of 30% by mass to 40% by mass is particularly preferable.

  The thermoplastic resin composition whose melt viscosity is controlled in the above range is dropped from the spinning nozzle of the melt-blown nonwoven fabric manufacturing apparatus. Generally, the melt-kneaded thermoplastic resin composition is continuously dropped from the spinning nozzle of the melt-blown nonwoven fabric manufacturing apparatus. However, in this step, the thermoplastic resin composition is^-9m³~ 10^-4m³The solution is dropped intermittently as a molten resin mass of Taking the melt viscosity of the thermoplastic resin composition at 200 ° C. into the above range, the volume 10^-9m³~ 10^-4m³The thermoplastic resin composition is dropped from the spinning nozzle in the form of droplets by intermittently dropping the molten resin mass from the spinning nozzle as the molten resin mass.
  Volume of molten resin mass is 10^-8m³~ 5.0 x 10^-5m³Preferably 10, ^-8m³~ 3.0 × 10^-5m³It is more preferable that Control of the amount of the molten resin mass can be performed by controlling the viscosity of the molten resin supplied from the melt extrusion device, the supply amount per unit time, the diameter of the spinning nozzle, the shape of the spinning nozzle, the material of the spinning nozzle, etc. it can.

The volume (m ³ ) of the molten resin mass can be measured by the following method.
The periphery of the spinning nozzle during spinning is photographed at 4000 fps (frames per second) using a high-speed camera (Phantom V9.0, Vision Research, Inc.), and a molten resin mass, ie, molten resin When the droplet was released from the spinning nozzle, the radius of the droplet was measured. Using the radius obtained by measurement, the volume of the molten resin mass was calculated as a cube of 4 / 3π × (radius). This operation was performed on 100 droplets, and the number average was taken as the volume of the molten resin mass. The frame rate represents the number of frames (number of still images: number of frames) to be processed per unit time in a moving image, and fps represents the number of still images captured per second.

  The thermoplastic resin composition in the molten state is dropped intermittently in a droplet state from the spinning nozzle, so that the freedom of deformation at the time of dropping of the droplet is greater than when the thermoplastic resin composition is continuously discharged. In the subsequent fiber forming process, the molten resin mass is formed from one molten resin mass because the molten resin mass is more susceptible to the influence of gravity by being dropped in a droplet state. The fiber to be treated is considered to be a fiber having a portion with a fine fiber diameter and a portion with a larger fiber diameter in effective ranges, respectively.

  As a melt-blowing spinning nozzle used when producing the non-woven fabric of the present embodiment, it can be appropriately selected from those used when producing a known melt-blown non-woven fabric using a thermoplastic resin composition. In order to form a thermoplastic resin fiber having an average fiber diameter of 5.0 μm or less, the nonwoven fabric of the present embodiment preferably uses a nozzle in the range of 0.03 mm to 0.30 mm as the hole diameter of the spinning nozzle It is more preferable to use a nozzle in the range of 0.06 mm to 0.15 mm. In addition, the thermoplastic resin fiber whose ratio of the peak fiber diameter with respect to the average fiber diameter which is a preferable aspect of this embodiment is 0.5 or less can also be manufactured using the nozzle which has a hole diameter as stated above.

Further, not only an apparatus provided with a single-pored spinning nozzle group but also an apparatus provided with a nozzle group having nozzles of two or more different pore sizes in a desired ratio may be used.
When manufacturing the nonwoven fabric of this embodiment using the apparatus which has a nozzle of two types of hole diameter, the nozzle (small hole diameter nozzle) whose nozzle hole diameter is in the range of 0.07 mm-0.3 mm, and the nozzle hole diameter is 0.5 An apparatus having a nozzle (large hole diameter nozzle) in the range of ̃1.2 mm can be used. As an apparatus having such a nozzle group, for example, the ratio of the hole diameter of the small hole nozzle to the large hole nozzle (large hole nozzle / small hole nozzle) exceeds 2, and the number of small hole nozzles and large hole nozzles An apparatus in which the ratio (small diameter nozzle / large diameter nozzle) is in the range of 3 to 20 can be mentioned.

(2. Fiber formation process)
In this step, gas is supplied to the molten resin mass dropped in the previous step to form a thermoplastic resin fiber.
The gas supplied to the molten resin mass may be the same gas as that in the commonly used melt-blown nonwoven fabric manufacturing apparatus, and a high-speed and high-temperature air stream (also referred to as hot air) jetted from the periphery of the spinning nozzle described above. Be applied).
The temperature of the supplied gas is preferably in the range of 200 ° C. to 400 ° C., and more preferably in the range of 250 ° C. to 350 ° C. Per hole nozzle as a supply amount of gas, 10 Nm ³ / m / h ~25Nm ³ / m / range when, more in the range of 12.5 nm ³ / m / h ~22.5Nm ³ / m / time preferable.
The flow rate of the gas may be constant or may vary within the above range.
The molten resin mass dropped from the spinning nozzle is formed into a fiber shape by supply of gas and solidified to form a thermoplastic resin fiber.

(3. Fiber accumulation process)
In this step, the formed thermoplastic resin fibers are accumulated to form a nonwoven fabric which is an aggregate of thermoplastic resin fibers.
In the fiber accumulation step, the formed thermoplastic resin fibers are deposited as a self-adhesive microfiber to a predetermined thickness on a collection belt to produce a web-like nonwoven fabric.
In the production of the web-like non-woven fabric, the deposited web can be subjected to an entangling process, if necessary.
As a method of entangling the deposited web, for example, a method of thermocompression bonding using an embossing roll, a flat roll (metal roll, rubber roll) or the like; a method of fusing by ultrasonic waves; an entanglement of fibers using a water jet Various methods such as a method of causing hot air through, a method of using a needle punch, and the like can be mentioned.
Among them, for the purpose of improving the uniformity of the non-woven fabric, a method of thermocompression bonding treatment using a flat roll having a uniform surface, or a method of fusing by hot air through is preferable.

  The nonwoven fabric of the present embodiment may be used alone, and within the range not impairing the effects of the present invention, cotton, cupra, rayon, polyolefin fiber, polyamide fiber, polyester fiber, etc. according to the purpose of use of the nonwoven fabric And at least one of a staple fiber non-woven fabric and a filament non-woven fabric formed of fibers selected from

For example, in order to reinforce strength, it is possible to adopt a method in which the nonwoven fabric of the present embodiment and the spun bond nonwoven fabric are integrated to form a laminate.
In the case of laminating with another nonwoven fabric, for example, a method of forming the nonwoven fabric of the present embodiment by directly depositing fibers obtained from the thermoplastic resin composition described above by a melt-blowing method on a spunbond nonwoven fabric, After the nonwoven fabric of the present embodiment is formed, a method of manufacturing a two-layered laminate by fusing the spunbond nonwoven fabric and the nonwoven fabric of the present embodiment by heat embossing or the like, separately from the previously produced spunbond nonwoven fabric. Although the method etc. which overlap | superpose the non-woven fabric of this embodiment, and fuse | melt it by heating pressurization etc., and manufacture a laminated body etc. are employable, it is not limited to these methods.

  The non-woven fabric of the present embodiment has the above-described structure, so that the surface area is large and the fine particle rejection rate is good, and in the preferable aspect of the present embodiment, the resistance to compression is further improved. be able to.

<Filter>
The filter of the present embodiment includes the nonwoven fabric of the present embodiment described above. By using the non-woven fabric of the present embodiment as a filter, a filter having a high fine particle rejection can be obtained, and in a preferred embodiment, a filter having a good resistance to fluid can be obtained.
The nonwoven fabric of the present embodiment may be used alone as a filter, or may be used as a laminate with another nonwoven fabric as described above, and may be further laminated with a reinforcing material such as a mesh other than the nonwoven fabric. You may use.

  The nonwoven fabric of the present embodiment is widely applicable as a filter for liquid and a filter for gas because it has a region with extremely thin fiber diameter and a region with a larger fiber diameter. Among them, when used for separation of gel particles etc., gel particle coverage is high compared to the case of using other non-woven fabrics, and gel particles are less likely to be clogged, resulting in longer life, so gel particles Its effect is remarkable when used in separation applications.

The nonwoven fabric of the present embodiment can be developed for the use described in "Basic knowledge of nonwoven fabric" published by Japan Nonwovens Association, but has excellent flexibility because it contains fibers with extremely small diameter compared to conventional nonwoven fabrics. In addition, by forming the region having thicker fibers, the compression resistance is further improved. Therefore, the nonwoven fabric of the present embodiment can be suitably used for various sanitary materials such as disposable diapers, sanitary napkins, masks, and medical dressings, clothing, and protective clothing.
Furthermore, since the nonwoven fabric of the present embodiment contains fibers with extremely small diameter, the surface area is large, voids are sufficiently formed in the nonwoven fabric, and since the compression resistance is good, oil absorbents, wipers, It can be suitably used as a sound absorbing material, a heat insulating material, a shock absorbing material, a surface protective material and the like.

  Hereinafter, the present invention will be more specifically described based on examples, but the present invention is not limited to these examples.

Example 1
(Preparation of Thermoplastic Resin Composition)
Propylene homopolymer [MFR = 1550 g / 10 min (measured at a temperature of 230 ° C. and a load of 2.16 kg according to ASTM D1238), hereinafter, a propylene homopolymer is described as “PP”] to 60 mass%, Polypropylene-based WAX (Mitsui Chemical Co., Ltd. trade name: Mitsui High Wax (registered trademark) NP055, density 900 kg / m ³ , hereinafter, polypropylene-based WAX is described as “WAX”) 40% by mass added, and thermoplastic resin Composition A was obtained.

(Manufacture of non-woven fabric)
Thermoplastic resin obtained using a melt-blown nonwoven fabric manufacturing apparatus equipped with a melt-blowing die having a nozzle with a nozzle hole diameter of 0.12 mmφ, an extrusion temperature of 200 ° C., and a dropping amount of molten resin per nozzle hole of 0.009 g / min. Composition A was extruded intermittently. The volume of the molten resin mass of the thermoplastic resin composition A dropped intermittently from the spinning nozzle was measured by the method described above. The results are shown in Table 1 below.
Intermittently molten resin mass dripped from the spinning nozzle, heated air blown out from both sides of the spinning nozzle ^{(290 ℃, 300Nm 3 / m} / time, i.e. the nozzle 1 15Nm ³ / m / hr per hole) by, the fibrous It was molded and solidified to form a thermoplastic resin fiber. The formed thermoplastic resin fiber was collected at a distance of 10 cm from the spinning nozzle to obtain the nonwoven fabric of Example 1.
The fiber diameter was measured by the method as stated above about the obtained nonwoven fabric. The results are shown in Table 1. Moreover, the graph which shows logarithmic frequency distribution of the fiber diameter in the nonwoven fabric of Example 1 is shown in FIG. It was 4.3 Pa.s when the melt viscosity at 200 degrees C of the obtained nonwoven fabric was measured by the method similar to the viscosity measurement method of the thermoplastic resin composition A.

  In addition, the structure of the die | dye for melt blows of the melt blow nonwoven fabric manufacturing apparatus used for manufacture of the nonwoven fabric is shown in FIG. As shown in FIG. 2, on the lower surface side of the melt-blowing die 4, a die nose 12 is disposed, and a nozzle 16 in which a plurality of holes 14 are arranged in a row is disposed. Then, the molten resin supplied into the resin passage 18 is pushed downward from the holes 14 of the nozzle 16. In addition, in FIG. 2, only the one fiber 10 to be extruded is shown. On the other hand, slits 31 and 31 are formed so as to sandwich the row of holes 14 of the nozzle 16 from both sides, and the air passages 20 a and 20 b are formed by these slits 31 and 31. Then, the high temperature and high pressure air sent from the air passages 20a and 20b is ejected together with the molten resin at the time of the extrusion of the molten resin.

Example 2
The nonwoven fabric of Example 2 was obtained in the same manner as the method described in Example 1 except that the dropping amount of the molten resin per nozzle hole was changed to 0.018 g / min.
The volume of the molten resin mass dropped from the spinning nozzle and the fiber diameter of the obtained non-woven fabric were measured in the same manner as in Example 1. The measurement results are shown in Table 1 below. Moreover, the graph which shows logarithmic frequency distribution of the fiber diameter in the nonwoven fabric of Example 2 is shown in FIG.

[Example 3]
(Preparation of Thermoplastic Resin Composition)
A thermoplastic resin was prepared in the same manner as in the preparation of the thermoplastic resin composition A, except that the addition amount of WAX was changed to 30% by mass with respect to 70% by mass of PP used for the thermoplastic resin composition A in Example 1. Composition B was obtained.
The nonwoven fabric of Example 3 was obtained in the same manner as the method described in Example 1 except that the composition was changed to the thermoplastic resin composition B.
The volume of the molten resin mass dropped from the spinning nozzle and the fiber diameter of the obtained non-woven fabric were measured in the same manner as in Example 1. The measurement results are shown in Table 1 below. Moreover, the graph which shows logarithmic frequency distribution of the fiber diameter in the nonwoven fabric of Example 3 is shown in FIG.

Comparative Example 1
The nonwoven fabric of Comparative Example 1 is obtained by the same method as described in Example 1 except that the discharge amount of the molten resin per nozzle hole is changed to 0.030 g / min, including setting of heating air. The
When an image obtained by photographing under the same conditions as in Example 1 was observed with an apparatus used when measuring the volume of the molten resin mass, the peripheral portion of the spinning nozzle during spinning was discharged from the spinning nozzle The thermoplastic resin composition was discharged continuously, and no molten resin lump consisting of the thermoplastic resin composition was observed.
The fiber diameter of the obtained nonwoven fabric of Comparative Example 1 was measured in the same manner as Example 1. The measurement results are shown in Table 1. Moreover, the graph which shows logarithmic frequency distribution of the fiber diameter in the nonwoven fabric of the comparative example 1 is shown in FIG.

Comparative Example 2
A nonwoven fabric of Comparative Example 2 was obtained by the same method as that described in Example 1 except that the composition containing no WAX was used as the thermoplastic resin composition, including the setting of heated air.
When an image obtained by photographing under the same conditions as in Example 1 was observed with an apparatus used when measuring the volume of the molten resin mass, the peripheral portion of the spinning nozzle during spinning was discharged from the spinning nozzle The thermoplastic resin composition was discharged continuously, and no molten resin lump consisting of the thermoplastic resin composition was observed.
The fiber diameter of the obtained nonwoven fabric of Comparative Example 1 was measured in the same manner as Example 1. The measurement results are shown in Table 1. Moreover, the graph which shows logarithmic frequency distribution of the fiber diameter in the nonwoven fabric of the comparative example 2 is shown in FIG.

As shown in Table 1, the nonwoven fabrics of Examples 1 to 3 have a region of fine fiber diameter of 100 nm to 200 nm, and the peak fiber diameter is smaller than the average fiber diameter, and the second peak Since the fiber diameter is larger than the average fiber diameter, it can be expected that the nonwoven fabric has a large surface area and good resistance to pressure.
On the other hand, in the nonwoven fabrics of Comparative Example 1 and Comparative Example 2 in which the first peak fiber diameter relative to the average fiber diameter exceeds 0.5, a region with a fine fiber diameter of 100 nm to 200 nm did not exist.
FIG. 1 is a graph showing logarithmic frequency distribution of fiber diameter in nonwoven fabrics of Examples 1 to 3 and Comparative Examples 1 and 2. From the graph of FIG. 1, in the nonwoven fabrics of Examples 1 to 3, the high peak on the side of the fiber diameter smaller than the average fiber diameter (the first peak corresponding to the most frequent fiber diameter) and the average fiber diameter It can be seen that on the side of thin fiber diameter, a bright second peak lower than the first peak is observed, and the non-woven fabric of the example shows a unique fiber diameter distribution.
From the comparison with Examples 1 to 3 and Comparative Examples 1 and 2, when the thermoplastic resin composition is discharged from the spinning nozzle, the present embodiment is carried out according to the manufacturing method in which the thermoplastic resin composition is intermittently dropped as a molten resin mass. It can be seen that the non-woven fabric of the example having the fiber diameter distribution defined in the form is easily formed using the existing melt-blown non-woven fabric manufacturing apparatus.

The disclosure of Japanese Patent Application 2016-026803, filed February 16, 2016, is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are as specific and distinct as when individual documents, patent applications, and technical standards are incorporated by reference. Incorporated herein by reference.

Claims (10)

The average fiber diameter is at 5μm or less, seen containing a thermoplastic resin fiber in which the fiber diameter cumulative frequency 100nm~200nm occurs more than 3.0%,
The said thermoplastic resin fiber is a nonwoven fabric whose ratio of the peak fiber diameter with respect to an average fiber diameter is 0.5 or less . The non-woven fabric according to claim 1, wherein the viscosity measured by melting at 200 ° C. is 0.1 Pa · s to 100.0 Pa · s. The non-woven fabric according to claim 1 or 2 , wherein the thermoplastic resin fiber contains a wax. The nonwoven fabric according to claim 3 , wherein the thermoplastic resin fiber contains the wax in an amount of 10% by mass to 60% by mass with respect to the total amount of the thermoplastic resin fiber. The peak fiber diameter of the said thermoplastic resin fiber is 1 micrometer or less, The nonwoven fabric of any one of Claims 1-4 . The nonwoven fabric according to any one of claims 1 to 5 , wherein the thermoplastic resin in the thermoplastic resin fiber is a homopolymer or copolymer of α-olefin. The nonwoven fabric according to any one of claims 1 to 6 , wherein the thermoplastic resin in the thermoplastic resin fiber is a polymer containing a structural unit derived from propylene. A filter comprising the nonwoven fabric according to any one of claims 1 to 7 . A thermoplastic resin composition containing a thermoplastic resin and having a melt viscosity at 200 ° C. of 0.1 Pa · s to 100.0 Pa · s is melted, and a melt of 10 ⁻⁹ m ³ to 10 ⁻⁴ m ³ from a spinning nozzle Intermittently dripping as a resin mass,
Supplying a gas to the dropped molten resin mass to form a thermoplastic resin fiber;
The method for producing a non-woven fabric according to any one of claims 1 to 7 , comprising accumulating the formed thermoplastic resin fibers. A thermoplastic resin composition containing a thermoplastic resin and having a melt viscosity at 200 ° C. of 0.1 Pa · s to 100.0 Pa · s is melted, and 10 from a spinning nozzle. ^-9 m ³ ~ 10 ^-4 m ³ Intermittently dripping as molten resin mass of
  Supplying a gas to the dropped molten resin mass to form a thermoplastic resin fiber;
  Collecting the formed thermoplastic resin fibers,
  The manufacturing method of the nonwoven fabric which manufactures the nonwoven fabric containing the thermoplastic resin fiber whose average fiber diameter is 5 micrometers or less, and the fiber diameter integrated frequency of 100 nm-200 nm is 3.0% or more.