Melt-blown nonwoven fabric, laminate, filter for mask, and mask

Abstract

Provided is a melt-blown nonwoven fabric or the like that is not susceptible to breakage and has high particle collection efficiency. The present invention relates to a melt-blown nonwoven fabric or the like comprising a fiber formed from a resin composition containing a poly (3-hydroxyalkanoate)-based resin containing a copolymer having a 3-hydroxybutyrate unit, the copolymer having a 3-hydroxybutyrate unit, and the copolymer having a 3-hydroxybutyrate unit. The content ratio of the 3-hydroxybutyrate unit in the poly (3-hydroxyalkanoate)-based resin is from 80.0 mol% to 93.5 mol% (inclusive), and the average value of the fiber diameter in the fiber is 8.0 [mu] m or less.

Description

Technical Field

[0001] The present invention relates to a melt-blown nonwoven fabric, a laminate, a filter for a mask, and a mask. Background Art

[0002] Meltblown nonwoven fabrics are nonwoven fabrics obtained by meltblowing in which a polymer and hot air are ejected from a spinning nozzle together. In addition, meltblown nonwoven fabrics have a microporous structure.

[0003] Meltblown nonwoven fabrics can be used as materials such as removal filters (including concepts such as mask filters and barrier filters) for removing particles (e.g., particles attached with viruses, etc., pollen, etc.), blood filters for capturing blood cells, and filters for beverage extraction (e.g., coffee drip filters, tea bags, etc.) (e.g., Patent Document 1).

[0004] As fibers constituting nonwoven fabrics, fibers containing poly(3-hydroxyalkanoate)-based resins, which are biodegradable resins, are used from the viewpoint of reducing the burden on the global environment (for example, Patent Document 2).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2022-505070

[0008] Patent Document 2: International Publication No. 2019 / 142920 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, melt-blown nonwoven fabrics are required to have high efficiency in capturing particles (for example, particles to which blood cells, pollen, coffee powder, tea leaves, viruses, etc. are attached).

[0011] Thus, regarding the melt-blown nonwoven fabric, the particle collection efficiency is improved by charging the nonwoven fabric with corona discharge.

[0012] However, to date, there has been no sufficient research on improving the particle collection efficiency of melt-blown nonwoven fabrics by using techniques other than electrification processing.

[0013] In addition, the meltblown nonwoven fabric may also be required to be not easily broken.

[0014] Therefore, the problem of the present invention is to provide a meltblown nonwoven fabric that is not easily broken and has high particle collection efficiency. In addition, the problem of the present invention is to provide a laminated body having the above-mentioned meltblown nonwoven fabric, a mask filter formed of the above-mentioned meltblown nonwoven fabric or the above-mentioned laminated body, and a mask having the mask filter.

[0015] Solutions to the problem

[0016] A first aspect of the present invention relates to a meltblown nonwoven fabric comprising fibers, wherein:

[0017] The fiber is formed from a resin composition containing a poly(3-hydroxyalkanoate) resin.

[0018] The poly(3-hydroxyalkanoate) resin comprises a copolymer having 3-hydroxybutyrate units.

[0019] The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 80.0 mol% or more and 93.5 mol% or less,

[0020] In the above fibers, the average fiber diameter is 8.0 μm or less.

[0021] A second aspect of the present invention relates to a laminate comprising a first nonwoven fabric and a second nonwoven fabric laminated on at least one surface of the first nonwoven fabric, wherein:

[0022] The first nonwoven fabric is the meltblown nonwoven fabric.

[0023] The second nonwoven fabric is a nonwoven fabric containing cellulose fibers.

[0024] A third aspect of the present invention relates to a mask filter formed of the meltblown nonwoven fabric or the laminate.

[0025] A fourth aspect of the present invention relates to a mask including a mask body and the mask filter described above.

[0026] Effects of the Invention

[0027] According to the present invention, a meltblown nonwoven fabric that is not easily broken and has high particle collection efficiency can be provided. In addition, according to the present invention, a laminated body having the above-mentioned meltblown nonwoven fabric, a mask filter formed of the above-mentioned meltblown nonwoven fabric or the above-mentioned laminated body, and a mask having the mask filter can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of a meltblown nonwoven fabric production apparatus.

[0029] Figure 2 This is a schematic three-dimensional diagram of the nozzle.

[0030] Figure 3 A schematic cross-sectional view of the nozzle hole and conveyor belt.

[0031] Figure 4 This is a photograph of the first test piece.

[0032] Figure 5 This is a photograph of the second test piece.

[0033] Figure 6 This is a photo of the main body of the mask.

[0034] Explanation of symbols

[0035] 1: Meltblown nonwoven fabric manufacturing device

[0036] 2: Hopper

[0037] 3: Extruder

[0038] 4: Gear pump

[0039] 5: Filter

[0040] 6: Mixing machine

[0041] 7: Nozzle

[0042] 7a: Nozzle hole

[0043] 8: Collector

[0044] 8a: Conveyor Belt

[0045] 8b: Roller

[0046] 9: Coiler,

[0047] A: Mixture

[0048] B: No. 1 meltblown nonwoven fabric

[0049] C: Gas DETAILED DESCRIPTION

[0050] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0051] <Meltblown nonwoven fabric>

[0052] First, the melt-blown nonwoven fabric according to the present embodiment will be described.

[0053] The melt-blown nonwoven fabric of the present embodiment includes fibers.

[0054] The fibers are formed from a resin composition containing a poly(3-hydroxyalkanoate)-based resin.

[0055] The poly(3-hydroxyalkanoate)-based resin includes a copolymer having a 3-hydroxybutyrate unit.

[0056] The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 80.0 mol% or more and 93.5 mol% or less.

[0057] In the above fibers, the average fiber diameter is 8.0 μm or less.

[0058] The melt-blown nonwoven fabric of the present embodiment is a nonwoven fabric obtained by a melt-blowing method.

[0059] In addition, the melt-blown nonwoven fabric of the present embodiment also includes the concept of a nonwoven fabric obtained by a spun-blown (registered trademark) method.

[0060] The resin composition contains a polymer component. In addition, the resin composition may further contain an additive.

[0061] The polymer component contains a poly(3-hydroxyalkanoate)-based resin.

[0062] The polymer component may contain other polymers in addition to the poly(3-hydroxyalkanoate)-based resin.

[0063] The poly(3-hydroxyalkanoate)-based resin is a polyester containing 3-hydroxyalkanoic acid as a monomer.

[0064] That is, the poly(3-hydroxyalkanoate)-based resin is a resin containing 3-hydroxyalkanoic acid as a structural unit.

[0065] In addition, the poly(3-hydroxyalkanoate)-based resin is a biodegradable polymer.

[0066] It should be noted that the "biodegradability" in the present embodiment refers to the property of being decomposed into low molecular weight compounds by microorganisms in nature. Specifically, the presence or absence of biodegradability can be determined by tests that meet the respective environments, such as ISO 14855 (compost) and ISO 14851 (activated sludge) under aerobic conditions and ISO 14853 (aqueous phase) and ISO 15985 (solid phase) under anaerobic conditions. In addition, the decomposability of microorganisms in seawater can be evaluated by measuring biochemical oxygen demand.

[0067] The poly(3-hydroxyalkanoate)-based resin includes a copolymer having a 3-hydroxybutyrate unit.

[0068] In the copolymer having a 3-hydroxybutyrate unit, examples of the monomer unit other than the 3-hydroxybutyrate unit include a hydroxyalkanoate unit other than the 3-hydroxybutyrate unit.

[0069] Examples of the hydroxyalkanoate unit other than the 3-hydroxybutyrate unit include 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxyoctadecanoate, 3-hydroxyvalerate, and 4-hydroxybutyrate.

[0070] Examples of the copolymer having a 3-hydroxybutyrate unit include P3HB3HH, P3HB3HV, P3HB4HB, poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate).

[0071] Here, P3HB3HH refers to poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0072] P3HB3HV refers to poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

[0073] P3HB4HB refers to poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

[0074] The poly(3-hydroxyalkanoate)-based resin may include only one copolymer having a 3-hydroxybutyrate unit, or may include two or more copolymers.

[0075] As the copolymer having 3-hydroxybutyrate units, P3HB3HH is preferred.

[0076] The resin composition preferably contains 50% by mass or more of a copolymer having a 3-hydroxybutyrate unit, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0077] In the poly(3-hydroxyalkanoate)-based resin, the content of the 3-hydroxybutyrate unit is 80.0 mol% to 93.5 mol%, preferably 82.0 mol% to 93.0 mol%, and more preferably 85.0 mol% to 91.6 mol%.

[0078] When the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 80.0 mol % or more, the rigidity of the fiber becomes high.

[0079] The melt-blown nonwoven fabric of the present embodiment is not easily broken by making the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin not more than 93.5 mol%. In addition, the melt-blown nonwoven fabric of the present embodiment is not easily linted by making the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin not more than 93.5 mol%.

[0080] It should be noted that the content ratio of the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin refers to the content ratio of the 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate)-based resin contained in the nonwoven fabric.

[0081] The content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin can be determined as follows.

[0082] First, 2 mL of a mixed solution of sulfuric acid and methanol (volume of sulfuric acid:volume of methanol=15:85) and 2 mL of chloroform were added to 20 mg of the dried poly(3-hydroxyalkanoate) resin of the melt-blown nonwoven fabric, and the obtained sample was sealed. The sample was heated at 100° C. for 140 minutes in a sealed state to obtain a first reaction liquid containing methyl ester as a decomposition product of the poly(3-hydroxyalkanoate) resin.

[0083] Then, the first reaction liquid was cooled, and 1.5 g of sodium bicarbonate was gradually added to the cooled first reaction liquid for neutralization, and the mixture was left to stand until generation of carbon dioxide stopped, thereby obtaining a second reaction liquid.

[0084] Furthermore, the second reaction liquid was fully mixed with 4 mL of diisopropyl ether to obtain a mixture.

[0085] Next, the mixture was centrifuged to obtain a supernatant.

[0086] Then, the monomer unit composition of the above-mentioned decomposition product in the supernatant was analyzed by capillary gas chromatography under the following conditions to determine the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin.

[0087] Gas chromatograph: GC-17A manufactured by Shimadzu Corporation

[0088] Capillary column: NEUTRABOND-1 manufactured by GL Sciences (column length: 25 m, column inner diameter: 0.25 mm, liquid film thickness: 0.4 μm)

[0089] Carrier gas: He

[0090] Column inlet pressure: 100 kPa

[0091] Sample volume: 1 μL

[0092] Regarding the temperature conditions, the temperature was raised at a rate of 8°C / min at 100 to 200°C, and further at a rate of 30°C / min at 200 to 290°C.

[0093] In addition, the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin contained in the raw material composition (the "raw material composition" will be described below) can be used as the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin of the above-mentioned melt-blown nonwoven fabric.

[0094] From the viewpoint of improving the mechanical properties of the melt-blown nonwoven fabric, the poly(3-hydroxyalkanoate)-based resin preferably contains a poly(3-hydroxyalkanoate)-based resin component having a 3-hydroxybutyrate unit content of 76 mol % or less.

[0095] In the poly(3-hydroxyalkanoate)-based resin component, the content of 3-hydroxybutyrate units is 0 to 76 mol %, preferably 1 to 76 mol %, and more preferably 50 to 76 mol %.

[0096] As the poly(3-hydroxyalkanoate)-based resin component, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and the like are preferred.

[0097] (MIBK separation method)

[0098] Whether the poly(3-hydroxyalkanoate)-based resin contains the poly(3-hydroxyalkanoate)-based resin component can be determined by, for example, a solvent separation method utilizing the difference in solubility in methyl isobutyl ketone (MIBK) (also referred to as “MIBK separation method”).

[0099] That is, the poly(3-hydroxyalkanoate)-based resin was separated into a MIBK-soluble fraction and a MIBK-insoluble fraction by the MIBK separation method. Since the content ratio of 3-hydroxybutyrate units in any fraction was 76 mol% or less, it was confirmed that the poly(3-hydroxyalkanoate)-based resin contained the poly(3-hydroxyalkanoate)-based resin component.

[0100] The specific separation steps are as follows. First, weigh about 100 mg of poly(3-hydroxyalkanoate) resin in a screw-capped test tube, add 10 ml of MIBK, and seal the lid. Thereafter, oscillate and mix while heating at 140°C for about 1 to 3 hours to completely dissolve the poly(3-hydroxyalkanoate) resin. After complete dissolution, place it at 25°C for 1 minute to lower its temperature below the boiling point, quickly transfer all the dissolved liquid to a centrifugal sedimentation tube whose weight has been measured in advance, and seal the lid. Place the centrifugal sedimentation tube with the lid on for further 15 minutes at 25°C to precipitate part of the dissolved material. Separate the precipitate and the dissolved liquid by centrifugation (9000 rpm, 5 minutes), and transfer all the dissolved liquid to an aluminum cup whose weight has been measured in advance. Add 10 ml of MIBK to the centrifugal sedimentation tube with the precipitate remaining, mix with a vortex agitator, centrifuge again (9000 rpm, 5 minutes), and transfer the solution to the aluminum cup to which the above-mentioned dissolved liquid has been added. The aluminum cup was heated at 120°C for 30 minutes to volatilize MIBK and precipitate the dissolved matter. Furthermore, the precipitate remaining in the aluminum cup and the precipitate remaining in the centrifugal sedimentation tube were vacuum dried at 100°C for 6 hours. The precipitate remaining in the aluminum cup was taken as the MIBK soluble fraction, and the precipitate remaining in the centrifugal sedimentation tube was taken as the MIBK insoluble fraction, and they were weighed separately. It was confirmed that the difference between the total weight of the MIBK soluble fraction and the MIBK insoluble fraction and the weight of the poly(3-hydroxyalkanoate) resin initially measured was within ±3%.

[0101] The content ratio of 3-hydroxybutyrate units in each of the MIBK soluble fraction and the MIBK insoluble fraction can be measured by the above-mentioned method.

[0102] The content ratio of the 3-hydroxybutyrate unit in either the MIBK soluble fraction or the MIBK insoluble fraction is preferably 0 to 76 mol %, more preferably 1 to 76 mol %, and even more preferably 50 to 76 mol %.

[0103] Examples of poly(3-hydroxyalkanoate)-based resins other than copolymers having 3-hydroxybutyrate units include P3HB, poly(3-hydroxyvalerate), and poly(3-hydroxyhexanoate).

[0104] Here, P3HB refers to poly(3-hydroxybutyrate) as a homopolymer.

[0105] It should be noted that P3HB has a function of promoting the crystallization of P3HB itself and poly(3-hydroxyalkanoate)-based resins other than P3HB.

[0106] The other polymer is preferably biodegradable.

[0107] Examples of other biodegradable polymers include polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene terephthalate adipate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, unmodified starch, modified starch, cellulose acetate, and chitosan.

[0108] The polycaprolactone is a polymer obtained by ring-opening polymerization of ε-caprolactone.

[0109] The resin composition may contain one other polymer or two or more other polymers.

[0110] Since the melt-blown nonwoven fabric of the present embodiment contains a biodegradable polymer, even if the melt-blown nonwoven fabric is discarded in the environment, the melt-blown nonwoven fabric is easily decomposed in the environment, and thus the burden on the environment can be suppressed.

[0111] The above-mentioned resin composition may further contain additives.

[0112] Examples of the additives include crystal nucleating agents, lubricants, stabilizers (antioxidants, ultraviolet absorbers, etc.), colorants (dyes, pigments, etc.), plasticizers, inorganic fillers, organic fillers, antistatic agents, and the like.

[0113] The resin composition preferably contains a crystal nucleating agent as an additive.

[0114] The crystal nucleating agent is a compound that can promote the crystallization of the poly(3-hydroxyalkanoate)-based resin. In addition, the crystal nucleating agent has a melting point higher than that of the poly(3-hydroxyalkanoate)-based resin.

[0115] By making the resin composition contain a crystal nucleating agent, when a melt-blown nonwoven fabric is produced by a melt-blowing method, the crystallization of the poly(3-hydroxyalkanoate) resin can be promoted, and adjacent fibers are less likely to melt-bond. As a result, the coefficient of variation of the fiber diameter of the fiber can be easily reduced.

[0116] Examples of the crystal nucleating agent include inorganic substances (e.g., boron nitride, titanium oxide, talc, layered silicate, calcium carbonate, sodium chloride, metal phosphate, etc.); sugar alcohol compounds derived from natural substances (e.g., pentaerythritol, erythritol, galactitol, mannitol, arabitol, etc.); polyvinyl alcohol; chitin; chitosan; polyethylene oxide; aliphatic carboxylates; aliphatic alcohols; aliphatic carboxylic acid esters; dicarboxylic acid derivatives (e.g., dimethyl adipate, dibutyl adipate, diisodecyl adipate, didecyl adipate, etc.); butyl ester, etc.); cyclic compounds having C=O and a functional group selected from NH, S and O in the molecule (for example, indigo, quinacridone, quinacridone fuchsin, etc.); sorbitol derivatives (for example, dibenzylidene sorbitol, bis(p-methylbenzylidene) sorbitol, etc.); compounds containing a nitrogen-containing heteroaromatic core (for example, a pyridine ring, a triazine ring, an imidazole ring, etc.) (for example, pyridine, triazine, imidazole, etc.); phosphate compounds; diamides of higher fatty acids; metal salts of higher fatty acids; branched polylactic acid, etc.

[0117] It should be noted that P3HB, which is the poly(3-hydroxyalkanoate)-based resin, can also be used as a crystal nucleating agent.

[0118] These may be used alone or in combination of two or more.

[0119] As the crystal nucleating agent, from the viewpoint of the effect of improving the crystallization rate of the poly(3-hydroxyalkanoate) resin and the viewpoint of compatibility and affinity with the poly(3-hydroxyalkanoate) resin, sugar alcohol compounds, polyvinyl alcohol, chitin, and chitosan are preferred.

[0120] Among the sugar alcohol compounds, pentaerythritol is preferred.

[0121] The above-mentioned crystal nucleating agent preferably has a crystalline structure at room temperature (25)°C.

[0122] When the crystal nucleating agent has a crystalline structure at room temperature (25)°C, there is an advantage that the crystallization of the poly(3-hydroxyalkanoate)-based resin can be further promoted.

[0123] In addition, the crystal nucleating agent having a crystalline structure at room temperature (25)°C is preferably in a powdery state at room temperature (25)°C.

[0124] Furthermore, the average particle size of the crystal nucleating agent in a powdery state at room temperature (25)°C is preferably 10 μm or less.

[0125] The resin composition preferably contains 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more of the crystal nucleating agent based on 100 parts by mass of the poly(3-hydroxyalkanoate)-based resin.

[0126] The resin composition containing 0.1 parts by mass or more of the crystallization nucleating agent based on 100 parts by mass of the poly(3-hydroxyalkanoate) resin has the advantage of being able to further promote crystallization of the poly(3-hydroxyalkanoate) resin when producing a melt-blown nonwoven fabric by a melt-blowing method.

[0127] The resin composition preferably contains 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, of a crystal nucleating agent based on 100 parts by mass of the poly(3-hydroxyalkanoate)-based resin.

[0128] When the resin composition contains 2.5 parts by mass or less of the crystal nucleating agent based on 100 parts by mass of the poly(3-hydroxyalkanoate)-based resin, there is an advantage that fibers can be easily obtained when a melt-blown nonwoven fabric is produced by a melt-blowing method.

[0129] It should be noted that P3HB is a poly(3-hydroxyalkanoate) resin and can function as a crystal nucleating agent. Therefore, when the resin composition contains P3HB, the amount of P3HB is included in both the amount of the poly(3-hydroxyalkanoate) resin and the amount of the crystal nucleating agent.

[0130] The resin composition preferably contains the lubricant.

[0131] When a melt-blown nonwoven fabric is produced by a melt-blowing method, by making the fibers contain a lubricant, the smoothness of the fibers becomes good and the melt-bonding of the fibers can be suppressed.

[0132] On the other hand, when the resin composition contains no lubricant or contains a very small amount of lubricant, there are advantages such as increased tape adhesion of the nonwoven fabric and easier handling of the process for producing the nonwoven fabric.

[0133] Whether or not to add a lubricant and the amount of lubricant added can be appropriately determined according to the intended use of the meltblown nonwoven fabric.

[0134] Examples of the lubricant include compounds having an amide bond.

[0135] The compound having an amide bond preferably includes one or more selected from the group consisting of lauric acid amide, myristic acid amide, stearic acid amide, behenic acid amide, and erucic acid amide.

[0136] The content of the lubricant in the resin composition is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and further preferably 0.5 parts by mass or more relative to 100 parts by mass of the polymer component. By making the content of the lubricant in the resin composition 0.05 parts by mass or more relative to 100 parts by mass of the polymer component, there is an advantage that when a melt-blown nonwoven fabric is produced by a melt-blowing method, the melt-bonding of fibers can be further suppressed.

[0137] On the other hand, when the content of the lubricant in the resin composition is 0 to 0.2 parts by mass relative to 100 parts by mass of the polymer component, there is an advantage that the tape adhesion of the nonwoven fabric is improved and the process for producing the nonwoven fabric becomes easier to handle.

[0138] In addition, the content of the lubricant in the resin composition is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, further preferably 8 parts by mass or less, and most preferably 5 parts by mass or less, relative to 100 parts by mass of the above-mentioned polymer component. By setting the content of the lubricant in the resin composition to 12 parts by mass or less relative to 100 parts by mass of the polymer component, there is an advantage that the lubricant can be suppressed from seeping out on the fiber surface.

[0139] The melt flow rate (MFR) of the resin composition at 165° C. is preferably 50 to 1500 g / 10 min, more preferably 70 to 1500 g / 10 min, further preferably 80 to 1300 g / 10 min, particularly preferably 80 to 1200 g / 10 min.

[0140] By setting the melt flow rate of the resin composition in the above-mentioned fiber at 165° C. to 1500 g / 10 min or less, the strength and elongation of the meltblown nonwoven fabric are increased.

[0141] By making the melt flow rate of the resin composition in the above-mentioned fiber at 165°C be 50 g / 10 min or more, the tension of the fibrous melt can be reduced when the fibrous melt is stretched, and the fiber diameter of the fiber in the obtained meltblown nonwoven fabric can be easily reduced. As a result, the particle collection efficiency of the meltblown nonwoven fabric can be easily improved.

[0142] It should be noted that, for the melt flow rate (MFR) of the above-mentioned resin composition at 165°C, the melt volume flow rate (MVR) of the resin composition at 165°C is calculated using method B of ASTM-D1238 (ISO1133-1, JIS K7210-1:2011), and the melt flow rate (MFR) of the resin composition at 165°C is calculated based on the melt volume flow rate (MVR) of the resin composition at 165°C and the density of the resin composition.

[0143] The melt volume flow rate (MVR) of the resin composition at 165° C. is measured by heating 5 g or more of the resin composition at 165° C. for 4 minutes and then applying a load of 5 kg to the heated resin composition.

[0144] The weight average molecular weight of the resin composition is preferably 100,000 to 250,000, more preferably 110,000 to 200,000, and even more preferably 110,000 to 180,000.

[0145] When the weight average molecular weight of the resin composition in the fibers is 100,000 or more, the strength and elongation of the melt-blown nonwoven fabric are improved.

[0146] By making the weight average molecular weight of the resin composition in the above-mentioned fiber 250000 or less, the tension of the fibrous melt when stretching the fibrous melt can be reduced, and the fiber diameter of the fiber in the obtained meltblown nonwoven fabric can be easily reduced. As a result, it is easy to improve the particle collection efficiency of the meltblown nonwoven fabric.

[0147] The weight average molecular weight in the present embodiment is measured from a polystyrene-equivalent molecular weight distribution using gel permeation chromatography (GPC) using a chloroform eluent. As a column in the GPC, a column suitable for measuring the above-mentioned molecular weight can be used.

[0148] The average fiber diameter of the fibers is 8.0 μm or less, preferably 5.0 μm or less, more preferably 3.3 μm or less, and even more preferably 3.0 μm or less.

[0149] The average fiber diameter of the fibers is preferably 0.50 to 8.0 μm, more preferably 0.50 to 5.0 μm, further preferably 0.50 to 3.3 μm, further preferably 0.50 to 3.0 μm, particularly preferably 0.80 to 2.8 μm, and further preferably 1.0 to 2.6 μm.

[0150] The coefficient of variation of the fiber diameter in the above-mentioned fibers is preferably 0.40 or less, more preferably 0.36 or less, and further preferably 0.32 or less. In addition, the coefficient of variation of the fiber diameter in the above-mentioned fibers is, for example, 0.10 or more.

[0151] When the average fiber diameter of the fibers is 8.0 μm or less, the particle collection efficiency of the melt-blown nonwoven fabric increases.

[0152] When the average value of the fiber diameter of the fibers is 0.50 μm or more, the strength and elongation of the melt-blown nonwoven fabric are increased.

[0153] By making the coefficient of variation of the fiber diameter in the above-mentioned fibers less than 0.40, extremely thick fibers are reduced, and as a result, the particle collection efficiency of the melt-blown nonwoven fabric is further improved. In addition, by making the coefficient of variation of the fiber diameter in the above-mentioned fibers less than 0.40, extremely thin fibers are reduced, and as a result, the strength and elongation of the melt-blown nonwoven fabric are increased.

[0154] In addition, the average value and the coefficient of variation of the fiber diameter of the fibers can be obtained as follows.

[0155] First, a test piece was obtained from a melt-blown nonwoven fabric.

[0156] Next, photographs (1700 times) were taken at five locations on the surface of the test piece using a scanning electron microscope.

[0157] Then, the diameters (widths) of 20 or more fibers randomly selected per one photograph are measured.

[0158] Next, the arithmetic mean and coefficient of variation (= standard deviation / arithmetic mean) were calculated from the measured values ​​of the diameters (widths) of all the fibers.

[0159] The melt-blown nonwoven fabric of the present embodiment preferably has a weight per unit area of ​​20 to 80 g / m 2 , more preferably 25 to 77 g / m 2 , more preferably 30 to 75 g / m 2 .

[0160] By setting the unit area weight of the melt-blown nonwoven fabric of this embodiment to 20 g / m 2 As described above, the strength and elongation of the meltblown nonwoven fabric are increased, and at the same time, the particle collection efficiency of the meltblown nonwoven fabric is further increased.

[0161] In addition, by setting the unit area weight of the melt-blown nonwoven fabric of this embodiment to 80 g / m 2 Next, the liquid permeability (water permeability, etc.) or air permeability can be improved.

[0162] It should be noted that the basis weight of the melt-blown nonwoven fabric of the present embodiment can be obtained as follows.

[0163] First, a test piece is obtained from the melt-blown nonwoven fabric of the present embodiment.

[0164] The size of the test piece may be, for example, 100 mm×100 mm, 200 mm×200 mm, or the like.

[0165] Next, the weight of the test piece is measured using an electronic balance or the like.

[0166] Then, the weight of the test piece was divided by the area of ​​the test piece to calculate the weight per unit area.

[0167] The melt-blown nonwoven fabric of the present embodiment preferably has a thickness of 0.10 to 0.40 mm, and more preferably 0.15 to 0.35 mm.

[0168] By setting the thickness of the melt-blown nonwoven fabric of the present embodiment to 0.10 to 0.40 mm, a uniform melt-blown nonwoven fabric can be easily obtained when the melt-blown nonwoven fabric is produced.

[0169] Furthermore, by setting the thickness of the melt-blown nonwoven fabric of the present embodiment to 0.10 mm or more, the strength and elongation of the melt-blown nonwoven fabric are increased, and the particle collection efficiency of the melt-blown nonwoven fabric is further increased.

[0170] Furthermore, by setting the thickness of the melt-blown nonwoven fabric of the present embodiment to 0.40 mm or less, the liquid permeability (water permeability, etc.) or air permeability of the melt-blown nonwoven fabric can be improved.

[0171] It should be noted that the thickness of the meltblown nonwoven fabric of the present embodiment can be measured by using a thickness gauge at three or more locations of the meltblown nonwoven fabric, and the arithmetic average thereof can be used as the thickness of the meltblown nonwoven fabric.

[0172] As a thickness gauge, "PEACOCK" manufactured by Ozaki Manufacturing Co., Ltd. etc. are mentioned, for example.

[0173] The melt-blown nonwoven fabric of the present embodiment preferably has an average pore size of 2.5 μm or more and 10.0 μm or less, and more preferably 3.0 μm or more and 7.0 μm or less.

[0174] By setting the average pore size of the melt-blown nonwoven fabric of the present embodiment to 2.5 μm or more, the liquid permeability (water permeability, etc.) or air permeability of the melt-blown nonwoven fabric can be improved.

[0175] By setting the average pore size of the melt-blown nonwoven fabric of the present embodiment to 10.0 μm or less, the particle collection efficiency of the melt-blown nonwoven fabric is further increased.

[0176] The average pore size of the melt-blown nonwoven fabric of the present embodiment is a mean flow rate pore size determined in accordance with JIS K3832-1990 "Bubble point test method for microfiltration membrane units and modules".

[0177] The mean flow pore size can be measured using, for example, a Perm Porometer (manufactured by PMI Inc.) or the like.

[0178] The tensile elongation at break in the MD direction of the meltblown nonwoven fabric of the present embodiment (also referred to as "MD elongation") is preferably 50% or more, more preferably 100% or more, further preferably 120% or more, and particularly preferably 150% or more. The MD elongation of the meltblown nonwoven fabric of the present embodiment is, for example, 500% or less.

[0179] By setting the MD elongation to 50% or more, the melt-blown nonwoven fabric of the present embodiment becomes less likely to be torn even when pulled in the MD direction.

[0180] When the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 93.5 mol % or less, the MD elongation tends to be increased.

[0181] The tensile elongation at break in the CD direction of the meltblown nonwoven fabric of the present embodiment (also referred to as "CD elongation") is preferably 50% or more, more preferably 100% or more, further preferably 120% or more, and particularly preferably 150% or more. The CD elongation of the meltblown nonwoven fabric of the present embodiment is, for example, 500% or less.

[0182] By setting the CD elongation to 50% or more, the melt-blown nonwoven fabric of the present embodiment becomes less likely to be torn even when pulled in the CD direction.

[0183] When the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 93.5 mol % or less, the CD elongation tends to be increased.

[0184] By setting the tensile elongation at break of the melt-blown nonwoven fabric in the MD direction to 120% or more and setting the tensile elongation at break of the melt-blown nonwoven fabric in the CD direction to 120% or more, the melt-blown nonwoven fabric becomes even less likely to break.

[0185] Here, the MD direction is the direction (Machine Direction) in which the meltblown nonwoven fabric moves when the meltblown nonwoven fabric is manufactured.

[0186] The CD direction is a direction perpendicular to the MD direction.

[0187] The tensile elongation at break is also called the tensile elongation at break.

[0188] The ratio of the tensile elongation at break in the CD direction of the melt-blown nonwoven fabric to the tensile elongation at break in the MD direction of the melt-blown nonwoven fabric (CD elongation / MD elongation) is preferably 0.50 to 2.00, more preferably 0.56 to 1.80.

[0189] By setting the CD elongation / MD elongation to 0.50 to 2.00, when stress is applied to the meltblown nonwoven fabric of the present embodiment, stress concentration in only one of the CD direction and the MD direction of the meltblown nonwoven fabric is suppressed, resulting in that the meltblown nonwoven fabric becomes less likely to break.

[0190] When the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 93.5 mol % or less, it is easier to adjust the CD elongation / MD elongation ratio to be within the range of 0.50 to 2.00.

[0191] It should be noted that the tensile elongation at break can be measured using a constant rate of elongation tensile tester in accordance with JIS B7721:2018 "Tensile tester / compression tester-Calibration method and verification method for force measurement system". It should be noted that as a constant rate of elongation tensile tester, a universal testing machine (RTG-1210 manufactured by A&D Co., Ltd.) or the like can be used.

[0192] The tensile elongation at break can be specifically determined as follows.

[0193] First, a test piece (width: 8 mm, length: 40 mm) was cut out from the melt-blown nonwoven fabric.

[0194] Next, the test piece was mounted on a constant speed elongation tensile tester with an initial load and a clamping interval of 20 mm. In other words, the clamping interval when the initial load was applied to the test piece was set to 20 mm. The initial load was set to a state where the test piece was stretched by hand to a degree that no relaxation occurred.

[0195] Then, the load was increased at a tensile speed of 20 mm / min until the test piece broke.

[0196] Next, the tensile elongation at break was determined by the following formula.

[0197] Tensile elongation at break (%) = [(gripping interval at break - gripping interval when initial load is applied to the test piece) / gripping interval when initial load is applied to the test piece] × 100 (%)

[0198] The melt-blown nonwoven fabric of the present embodiment can be suitably used as, for example, a material for a filter.

[0199] Examples of the above-mentioned filters include: removal filters that remove particles (e.g., particles attached with viruses, etc., pollen, etc.) (e.g., filters for masks, etc.), blood filters that capture blood cells, filters for beverage extraction (e.g., filters for coffee drip filters, tea bags, etc.), etc.

[0200] In addition, two or more melt-blown nonwoven fabrics according to the present embodiment may be stacked and used as a material for a filter or the like.

[0201] <Laminated body>

[0202] The laminated body of the present embodiment includes a first nonwoven fabric and a second nonwoven fabric laminated on at least one surface of the first nonwoven fabric.

[0203] The first nonwoven fabric is a meltblown nonwoven fabric of the present embodiment.

[0204] The second nonwoven fabric contains cellulose fibers.

[0205] Examples of the cellulose-based fibers include cotton fibers, rayon (including concepts such as CUPRA (also referred to as “cupra”)), and acetate fibers.

[0206] Such a laminate is a laminate having high particle collection efficiency due to the first nonwoven fabric, and is a laminate having further improved strength due to the second nonwoven fabric.

[0207] Examples of the second nonwoven fabric include spunlace nonwoven fabrics.

[0208] <Filters for masks>

[0209] The mask filter of this embodiment is formed of the meltblown nonwoven fabric of this embodiment or the laminate of this embodiment.

[0210] <Mask>

[0211] The mask of this embodiment may include a mask body and the mask filter of this embodiment.

[0212] The mask body includes a pair of ear hooks and a holding portion capable of holding the mask filter.

[0213] The mask of this embodiment may be configured such that the mask filter is detachably attachable to the holding portion.

[0214] In addition, in the mask of this embodiment, the mask body and the mask filter may be integrated.

[0215] In addition, the mask of this embodiment can be a disposable mask.

[0216] The mask of this embodiment may have a structure of two or more layers in which the meltblown nonwoven fabric of this embodiment and a base sheet are stacked.

[0217] Specifically, the mask of this embodiment can have a three-layer structure in which a base sheet, the melt-blown nonwoven fabric of this embodiment and the base sheet are stacked in this order.

[0218] The base sheet has fibers.

[0219] Examples of the substrate sheet include nonwoven fabrics and woven fabrics.

[0220] Examples of the material of the fiber of the base sheet include cellulose-based fibers, polypropylene-based fibers (PP-based fibers), polyethylene terephthalate-based fibers (PET-based fibers), and polybutylene terephthalate-based fibers (PBT-based fibers).

[0221] Examples of the cellulose-based fibers as the fibers of the substrate sheet include cotton fibers, rayon (including concepts such as CUPRA (also referred to as “cupra”)), and acetate fibers.

[0222] The fibers of the base sheet may be long fibers or short fibers.

[0223] Examples of the nonwoven fabric as the base sheet include spunbonded nonwoven fabric and spunlaced nonwoven fabric.

[0224] Examples of the fabric as the base sheet include gauze, etc. Gauze has cotton fibers.

[0225] Examples of the nonwoven fabric as the base sheet containing cellulose fibers include nonwoven fabrics produced by a wet short fiber spunbonding method.

[0226] Examples of nonwoven fabrics produced by a wet staple spunbond method include TCF (registered trademark) series nonwoven fabrics (manufactured by Futamura Chemical Co., Ltd.) TCF (registered trademark) series nonwoven fabrics are nonwoven fabrics produced by a TCF (registered trademark) method.

[0227] Examples of the fibers constituting the spunlace nonwoven fabric include cellulose fibers, and specifically, rayon fibers.

[0228] Examples of the fibers constituting the spunbonded nonwoven fabric include polypropylene-based fibers (PP-based fibers), polyethylene terephthalate-based fibers (PET-based fibers), and polybutylene terephthalate-based fibers (PBT-based fibers).

[0229] In addition, the mask of the present embodiment has, for example, a three-layer structure in which a spunbond nonwoven fabric, a meltblown nonwoven fabric of the present embodiment, and a spunbond nonwoven fabric are sequentially stacked, that is, a three-layer structure of SMS. In other words, the mask can be an SMS mask.

[0230] The mask of this embodiment may include the second nonwoven fabric and / or woven fabric.

[0231] In addition, the mask of this embodiment can be a three-layer structure in which the second non-woven fabric or the woven fabric, the melt-blown non-woven fabric of this embodiment, and the second non-woven fabric or the woven fabric are sequentially stacked.

[0232] In other words, the mask of this embodiment can use a second nonwoven fabric and / or woven fabric instead of the above-mentioned spunbonded nonwoven fabric in the SMS mask.

[0233] <Method for producing meltblown nonwoven fabric>

[0234] The method for producing a melt-blown nonwoven fabric according to the present embodiment is a method for producing the above-mentioned melt-blown nonwoven fabric by a melt-blowing method.

[0235] The method for producing a melt-blown nonwoven fabric according to the present embodiment includes a step (A) of melting a raw material composition by heating to obtain a melt, and a step (B) of obtaining a melt-blown nonwoven fabric from the melt.

[0236] It should be noted that the above-mentioned melt-blowing method is a concept that also includes the spun-blowing (registered trademark) method.

[0237] The melt flow rate (MFR) of the raw material composition at 165° C. is preferably 30 to 1500 g / 10 min, more preferably 30 to 1000 g / 10 min, further preferably 50 to 1000 g / 10 min, particularly preferably 50 to 800 g / 10 min.

[0238] When the melt flow rate of the raw material composition at 165° C. is 1500 g / 10 min or less, the strength and elongation of the meltblown nonwoven fabric are further improved.

[0239] By making the melt flow rate of the raw material composition at 165°C to be 30 g / 10 min or more, the tension of the fibrous melt can be reduced when the fibrous melt is stretched, and the fiber diameter of the fibers in the obtained meltblown nonwoven fabric can be easily reduced. As a result, the particle collection efficiency of the meltblown nonwoven fabric is further improved.

[0240] It should be noted that, for the melt flow rate (MFR) of the above-mentioned raw material composition at 165°C, the melt volume flow rate (MVR) of the raw material composition at 165°C is calculated by method B of ASTM-D1238 (ISO1133-1, JIS K7210-1:2011), and the melt flow rate (MFR) of the raw material composition at 165°C is calculated based on the melt volume flow rate (MVR) of the raw material composition at 165°C and the density of the raw material composition.

[0241] The melt volume flow rate (MVR) of the raw material composition at 165° C. is measured by heating 5 g or more of the raw material composition at 165° C. for 4 minutes and then applying a load of 5 kg to the heated resin composition.

[0242] The weight average molecular weight of the raw material composition is preferably 100,000 to 350,000, more preferably 110,000 to 300,000, and even more preferably 110,000 to 250,000.

[0243] When the weight average molecular weight of the raw material composition is 100,000 or more, the strength and elongation of the melt-blown nonwoven fabric can be further improved.

[0244] By making the weight average molecular weight of the raw material composition below 350,000, the tension of the fibrous melt can be reduced when the fibrous melt is stretched, and the fiber diameter of the fibers in the obtained meltblown nonwoven fabric can be easily reduced. As a result, the particle collection efficiency of the meltblown nonwoven fabric is further improved.

[0245] In the method for producing a melt-blown nonwoven fabric according to the present embodiment, a melt-blown nonwoven fabric is obtained from the above-mentioned raw material composition using an apparatus for producing a melt-blown nonwoven fabric.

[0246] like Figure 1 As shown, the manufacturing device 1 of the above-mentioned meltblown nonwoven fabric comprises: an extruder 3 that obtains a melt by melting a raw material composition, a hopper 2 that supplies the raw material composition to the extruder 3, a kneader 6 that obtains a kneaded melt (hereinafter also referred to as "kneaded melt") by kneading the melt, a nozzle 7 that ejects the molten kneaded material in a fibrous form, a collector 8 that obtains a first meltblown nonwoven fabric B by capturing the fibrous molten kneaded material and cooling it, and a winding device 9 that winds up the first meltblown nonwoven fabric B.

[0247] Furthermore, the melt-blown nonwoven fabric production apparatus 1 may include a gear pump 4 for supplying the melt to the kneader 6 as necessary.

[0248] By providing the above-mentioned melt-blown nonwoven fabric production apparatus 1 with the gear pump 4, it is possible to suppress the amount of the melt supplied to the kneading machine 6 from fluctuating.

[0249] Furthermore, the melt-blown nonwoven fabric production apparatus 1 may include a filter 5 for removing foreign matter from the melt on the upstream side of the kneader 6 as necessary.

[0250] In the above step (A), the raw material composition is supplied to the extruder 3 via the hopper 2, and the raw material composition is melted to obtain a molten material.

[0251] The raw material composition supplied to the extruder 3 is preferably in a solid state, and more preferably in a pellet state.

[0252] In addition, from the viewpoint of suppressing hydrolysis of the resin in the raw material composition and suppressing oxidative degradation of the resin in the raw material composition, the raw material composition supplied to the extruder 3 is preferably dried by heating.

[0253] The moisture content of the raw material composition supplied to the extruder 3 is preferably 200 ppmw or less.

[0254] When drying the raw material composition, it is preferred to remove oxygen from the gas atmosphere. The gas atmosphere during drying is preferably an inert gas atmosphere (for example, nitrogen gas, etc.).

[0255] In the above step (A), the raw material composition may be dried before being supplied to the hopper 2 , or the hopper 2 may be configured as a hopper-type dryer to dry the raw material composition in the hopper 2 .

[0256] Examples of the extruder 3 include a single screw extruder, a co-rotating intermeshing twin screw extruder, a co-rotating non-intermeshing twin screw extruder, a counter-rotating non-intermeshing twin screw extruder, and a multi-screw extruder.

[0257] The extruder 3 is preferably a single-screw extruder from the viewpoint of being able to suppress thermal degradation of the resin during extrusion due to the small number of resin stagnation portions in the extruder and from the viewpoint of low equipment cost.

[0258] In the above step (A), the melt is supplied to the kneading machine 6 via the filter 5 by the gear pump 4, and the melt is kneaded by the kneading machine 6 to obtain a kneaded melt.

[0259] Examples of the filter 5 include a mesh, a pleated filter, and a leaf disk filter.

[0260] The filter 5 is preferably a leaf disk filter from the viewpoints of filtration accuracy, filtration area, and pressure resistance, and from the viewpoint of being less likely to be clogged by foreign matter.

[0261] As the filter material of the filter 5, for example, a sintered nonwoven fabric of metal fibers can be used.

[0262] In the above step (B), the melt-kneaded product is discharged as a melt from the nozzle 7 in the form of fibers.

[0263] The nozzle 7 is a spinning die.

[0264] exist Figure 2 In the embodiment, the nozzle 7 has a plurality of nozzle holes 7a for ejecting the molten kneaded material in the form of fibers. Figure 2 As shown, the nozzle 7 ejects a plurality of fibrous molten kneaded materials A.

[0265] It should be noted that the nozzle 7 may have only one nozzle hole 7a. That is, the nozzle 7 may eject only one raw material line A.

[0266] The plurality of nozzle holes 7a are opened downward.

[0267] The shape of the opening of the nozzle hole 7 a is, for example, a circular shape (including the concepts of a circular shape, a substantially circular shape, an elliptical shape, and a substantially elliptical shape).

[0268] The opening diameter of the nozzle hole 7a can be appropriately selected according to the fiber diameter of the melt-blown nonwoven fabric.

[0269] The opening diameter of the nozzle hole 7a is preferably 0.05 mm or more, more preferably 0.10 mm or more, and further preferably 0.12 mm or more.

[0270] The opening diameter is preferably 1.0 mm or less, more preferably 0.50 mm or less, further preferably less than 0.30 mm, and particularly preferably 0.25 mm or less.

[0271] The above-mentioned opening diameter refers to the arithmetic mean value of the above-mentioned opening diameters.

[0272] In the nozzle 7, a plurality of nozzle holes 7a are arranged in a row at intervals.

[0273] exist Figure 2 In the embodiment, a plurality of nozzle holes 7a are arranged in a row.

[0274] It should be noted that the number of rows of the plurality of nozzle holes 7a may be two or more. In other words, the melt-blowing method may be a spun-blowing (registered trademark) method.

[0275] The distance between adjacent nozzle holes 7a (hereinafter also referred to as "interval") is, for example, preferably 0.05 mm or more, more preferably 0.1 mm or more, and further preferably 0.25 mm or more.

[0276] By setting the distance (interval) between adjacent nozzle holes 7a to be 0.05 mm or more, it is possible to suppress the melt-bonding of adjacent fibers, and as a result, it is possible to reduce the coefficient of variation of the fiber diameter of the fibers.

[0277] The distance (interval) between the adjacent nozzle holes 7a is, for example, preferably 1.0 mm or less, more preferably 0.7 mm or less, and further preferably 0.5 mm or less.

[0278] The distances between the adjacent nozzle holes 7a may be equal or unequal, but are preferably equal from the viewpoint of facilitating production of a uniform melt-blown nonwoven fabric.

[0279] The distance (interval) between adjacent nozzle holes 7 a refers to the arithmetic mean value of the distance (interval) between adjacent nozzle holes 7 a .

[0280] The collector 8 has a collecting surface for collecting the kneaded material A in a fibrous state.

[0281] The collector 8 is a conveyor.

[0282] The conveyor includes a conveyor belt 8a having the collection surface and a plurality of rollers 8b for driving the conveyor belt 8a.

[0283] The collecting surface is arranged right below the nozzle hole 7a.

[0284] The conveyor belt 8a has air permeability. Specifically, the conveyor belt 8a is formed of a mesh-like material. That is, the collection surface is formed in a mesh shape.

[0285] It should be noted that the collector 8 only needs to have a collecting portion, and may be a collecting cylinder or a collecting net instead of the conveyor.

[0286] The distance between the nozzle hole 7a and the collection surface (hereinafter also referred to as "DCD") is preferably 20 mm or more, more preferably 50 mm or more, and even more preferably 80 mm or more.

[0287] In addition, the distance (DCD) between the nozzle hole 7a and the conveyor belt 8a as the collecting portion is preferably 250 mm or less.

[0288] The distance (DCD) between the nozzle hole 7a and the collection surface is the arithmetic mean of the distance (DCD) between the nozzle hole 7a and the collection surface.

[0289] The manufacturing device 1 of the above-mentioned meltblown nonwoven fabric is as follows Figure 3 As shown, the fibrous melt-kneaded material A is stretched by blowing a high-temperature gas C to the fibrous melt-kneaded material A.

[0290] In the above step (B), the high-temperature gas C is blown toward the fibrous melt-kneaded material A, and the high-temperature gas C blown toward the melt-kneaded material A is passed through the mesh-shaped conveyor belt 8a.

[0291] In the above step (B), in order to facilitate the high-temperature gas C blown to the molten kneaded product A to pass through the mesh conveyor 8a, it is preferred to use negative pressure (not shown) to suck the high-temperature gas C. As a result, it is easy to prevent the fibers from rebounding on the collecting surface of the mesh conveyor 8a, and as a result, it is easy to form the first melt-blown nonwoven fabric B in which the fibers are well melt-bonded to each other.

[0292] Then, in the step (B), the stretched fibrous melt-kneaded product A is collected by the conveyor 8a and cooled while being conveyed by the conveyor 8a, thereby obtaining a first melt-blown nonwoven fabric.

[0293] The material constituting the above-mentioned mesh-shaped collecting surface is not particularly limited as long as it has heat resistance to the temperature conditions related to the manufacture of the first meltblown nonwoven fabric B, does not excessively melt-bond to the first meltblown nonwoven fabric B, and can peel off the first meltblown nonwoven fabric B.

[0294] Examples of the gas C include air and inert gas (nitrogen gas or the like).

[0295] As a method of blowing the high-temperature gas C, there is a method of heating the gas C pressurized by a compressor (not shown) with a heater (not shown).

[0296] The air volume of the high-temperature gas C blown toward the fibrous melt-kneaded material A is preferably 500 NL / min or more, more preferably 1000 NL / min or more, and even more preferably 2000 NL / min or more.

[0297] The air volume of the high-temperature gas C blown toward the fibrous melt-kneaded material A is preferably 12000 NL / min or less, more preferably 10000 NL / min or less.

[0298] In the above step (B), the temperature and air volume of the high-temperature gas C are appropriately controlled in order to obtain a melt-blown nonwoven fabric having a high degree of crystallinity.

[0299] The moving speed of the first melt-blown nonwoven fabric B by the conveyor 8a (moving speed of the conveyor 8a) can be appropriately determined in consideration of the apparent density of the obtained melt-blown nonwoven fabric B after taking into account the ejection amount of the resin.

[0300] The moving speed is preferably in the range of 1.0 m / min to 6.0 m / min.

[0301] In the step (B), the first melt-blown nonwoven fabric B is transferred to the winding device 9 by the conveyor belt 8a, and the first melt-blown nonwoven fabric B is wound into a roll by the winding device 9.

[0302] The method for producing a melt-blown nonwoven fabric according to the present embodiment may include a step (C) of heating the first melt-blown nonwoven fabric B obtained in the step (B) to obtain a second melt-blown nonwoven fabric.

[0303] It should be noted that when the method for producing a meltblown nonwoven fabric of the present embodiment has the above-mentioned step (C), the second meltblown nonwoven fabric becomes the above-mentioned meltblown nonwoven fabric. On the other hand, when the method for producing a meltblown nonwoven fabric of the present embodiment does not have the above-mentioned step (C), the first meltblown nonwoven fabric becomes the above-mentioned meltblown nonwoven fabric.

[0304] In the method for producing a melt-blown nonwoven fabric according to the present embodiment, the nonwoven fabric becomes less likely to be torn by the step (C).

[0305] In addition, the method for producing a melt-blown nonwoven fabric of the present embodiment can improve the tensile elongation at break in the CD direction and the tensile elongation at break in the MD direction of the melt-blown nonwoven fabric by the step (C).

[0306] In addition, in the method for producing a melt-blown nonwoven fabric according to the present embodiment, the fibers are partially melt-bonded to each other in the step (C), and as a result, the fuzzing of the melt-blown nonwoven fabric can be easily suppressed.

[0307] The heating temperature in the step (C) is preferably in the range of 80°C to 135°C.

[0308] The range of the heating time within the preferred heating temperature range of the step (C) is preferably 2 to 300 minutes, more preferably 5 to 100 minutes, and even more preferably 10 to 50 minutes.

[0309] In the above step (C), by heating the above first meltblown nonwoven fabric within the preferred heating temperature range for more than 2 minutes, the tensile elongation at break of the meltblown nonwoven fabric in the CD direction and the tensile elongation at break of the meltblown nonwoven fabric in the MD direction can be further improved.

[0310] Furthermore, in the step (C), by heating the first melt-blown nonwoven fabric within the preferred heating temperature range for 300 minutes or less, the productivity of the second melt-blown nonwoven fabric is improved.

[0311] In the step (C), the first melt-blown nonwoven fabric may be heated using a gas within the preferred heating temperature range.

[0312] Examples of the gas include air and inert gas (nitrogen gas, etc.).

[0313] As a method for heating the above-mentioned first meltblown nonwoven fabric using a gas within the above-mentioned preferred heating temperature range, there can be cited: heating the above-mentioned first meltblown nonwoven fabric in a heating furnace using a gas within the above-mentioned preferred heating temperature range, and / or heating the above-mentioned first meltblown nonwoven fabric by blowing a gas within the above-mentioned preferred heating temperature range onto the above-mentioned first meltblown nonwoven fabric, etc.

[0314] Furthermore, in the step (C), the first melt-blown nonwoven fabric may be heated within the preferred heating temperature range by sandwiching the first melt-blown nonwoven fabric between a pair of heating rolls.

[0315] In the step (C), the first melt-blown nonwoven fabric is preferably heated in a non-contact manner within the heating temperature range.

[0316] In the step (C), when the first melt-blown nonwoven fabric is heated by sandwiching a pair of heating rolls, the first melt-blown nonwoven fabric may be melt-bonded to the heating rolls.

[0317] In the step (C), by heating the first meltblown nonwoven fabric in the preferred heating temperature range in a non-contact manner with the heating roller or the like, there is an advantage in that melt-adhesion of the first meltblown nonwoven fabric to the heating roller or the like can be suppressed.

[0318] Examples of a method for heating the first melt-blown nonwoven fabric in a non-contact manner within the preferred heating temperature range include a method of heating the first melt-blown nonwoven fabric using a gas within the preferred heating temperature range.

[0319] In the step (C), the first melt-blown nonwoven fabric may be heated in a state where the first melt-blown nonwoven fabric is rolled up.

[0320] In the step (C), the first meltblown nonwoven fabric may be heated by forming the first meltblown nonwoven fabric into a sheet instead of rolling it into a roll. For example, the first meltblown nonwoven fabric may be continuously heated while being conveyed in a long strip.

[0321] In the step (C), the heated first melt-blown nonwoven fabric is cooled to obtain a second melt-blown nonwoven fabric.

[0322] As a cooling method for the heated first meltblown nonwoven fabric, the heated first meltblown nonwoven fabric can be naturally cooled at room temperature and pressure. Alternatively, the heated first meltblown nonwoven fabric can be forcibly cooled by blowing gas (e.g., gas at room temperature) onto the heated first meltblown nonwoven fabric.

[0323] 〔Public Project〕

[0324] The following items disclose preferred embodiments.

[0325] 〔Item 1〕

[0326] A meltblown nonwoven fabric comprises fibers, wherein:

[0327] The fiber is formed from a resin composition containing a poly(3-hydroxyalkanoate) resin.

[0328] The poly(3-hydroxyalkanoate)-based resin comprises a copolymer having a 3-hydroxybutyrate unit,

[0329] The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 80.0 mol% or more and 93.5 mol% or less,

[0330] In the fibers, the average value of the fiber diameter is 8.0 μm or less.

[0331] 〔Item 2〕

[0332] The meltblown nonwoven fabric according to item 1, wherein

[0333] The average value of the fiber diameter is 5.0 μm or less.

[0334] 〔Item 3〕

[0335] The meltblown nonwoven fabric according to item 2, wherein

[0336] The average value of the fiber diameter is 3.0 μm or less.

[0337] [Item 4]

[0338] The melt-blown nonwoven fabric according to any one of items 1 to 3, wherein

[0339] The unit area weight of the meltblown nonwoven fabric is 20 to 80 g / m 2 .

[0340] 〔Item 5〕

[0341] The melt-blown nonwoven fabric according to any one of items 1 to 4, wherein

[0342] The weight average molecular weight of the resin composition is 100,000 to 250,000.

[0343] [Item 6]

[0344] The melt-blown nonwoven fabric according to any one of items 1 to 5, wherein

[0345] The tensile elongation at break of the meltblown nonwoven fabric in the MD direction is greater than 50%.

[0346] The tensile elongation at break of the meltblown nonwoven fabric in the CD direction is greater than 50%.

[0347] [Item 7]

[0348] The melt-blown nonwoven fabric according to any one of items 1 to 6, wherein

[0349] The ratio of the tensile elongation at break in the CD direction of the melt-blown nonwoven fabric to the tensile elongation at break in the MD direction of the melt-blown nonwoven fabric is 0.50 to 2.00.

[0350] 〔Item 8〕

[0351] The melt-blown nonwoven fabric according to any one of items 1 to 7, wherein

[0352] The poly(3-hydroxyalkanoate)-based resin includes a poly(3-hydroxyalkanoate)-based resin component having a 3-hydroxybutyrate unit content ratio of 76 mol % or less.

[0353] [Item 9]

[0354] A laminate comprising a first nonwoven fabric and a second nonwoven fabric laminated on at least one surface of the first nonwoven fabric, wherein:

[0355] The first nonwoven fabric is the meltblown nonwoven fabric described in any one of items 1 to 8;

[0356] The second nonwoven fabric is a nonwoven fabric containing cellulose fibers.

[0357] [Item 10]

[0358] A mask filter, comprising the meltblown nonwoven fabric according to any one of items 1 to 8 or the laminate according to item 9.

[0359] [Item 11]

[0360] A mask comprising a mask body and the mask filter according to item 10.

[0361] It should be noted that the present invention is not limited to the above-mentioned embodiments. In addition, the present invention is not limited to the above-mentioned effects. In addition, the present invention can be variously modified within the scope of the gist of the present invention.

[0362] Example

[0363] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. It should be noted that the present invention is not limited to these Examples.

[0364] The following materials were prepared.

[0365] (Poly(3-hydroxyalkanoate) resin (P3HA))

[0366] The following P3HA-1 was produced according to the method described in Example 1 of International Publication No. 2019 / 142845.

[0367] P3HA-1: P3HB3HH (content ratio of 3-hydroxybutyrate unit: 94.5 mol%, content ratio of 3-hydroxyhexanoate (3HH) unit: 5.5 mol%, weight average molecular weight: 390,000)

[0368] The following P3HA-2 was produced according to the method described in Example 6 of International Publication No. 2021 / 206155.

[0369] P3HA-2: P3HB3HH (content ratio of 3-hydroxybutyrate unit: 85.0 mol%, content ratio of 3-hydroxyhexanoate (3HH) unit: 15.0 mol%, weight average molecular weight: 530000) (weight ratio of MIBK soluble fraction: 54 wt%, content ratio of 3-hydroxybutyrate unit in MIBK soluble fraction: 74.0 mol%, content ratio of 3-hydroxyhexanoate (3HH) unit in MIBK soluble fraction: 26.0 mol%) (weight ratio of MIBK insoluble fraction: 46 wt%, content ratio of 3-hydroxybutyrate unit in MIBK insoluble fraction: 98.0 mol%, content ratio of 3-hydroxyhexanoate (3HH) unit in MIBK insoluble fraction: 2.0 mol%)

[0370] The P3HA-1 was treated under high temperature and high humidity (temperature: 120° C., humidity: 100%) for 5.9 hours using a highly accelerated life tester (EHS-222MD manufactured by ESPEC Corporation) to obtain the following P3HA-3.

[0371] P3HA-3: P3HB3HH (content ratio of 3-hydroxybutyrate unit: 94.5 mol%, content ratio of 3-hydroxyhexanoate (3HH) unit: 5.5 mol%, weight average molecular weight: 200,000)

[0372] The P3HA-2 was treated under high temperature and high humidity (temperature: 120° C., humidity: 100%) for 5.5 hours using a highly accelerated life tester (manufactured by ESPEC Corporation, EHS-222MD) to obtain the following P3HA-4.

[0373] P3HA-4: P3HB3HH (content ratio of 3-hydroxybutyrate unit: 85.0 mol%, content ratio of 3-hydroxyhexanoate (3HH) unit: 15.0 mol%, weight average molecular weight: 220,000)

[0374] In addition, the content ratio of the 3-hydroxybutyrate unit and the content ratio of the 3-hydroxyhexanoate (3HH) unit in P3HA-1 were calculated|required as follows.

[0375] First, 2 mL of a mixed solution of sulfuric acid and methanol (volume of sulfuric acid:volume of methanol=15:85) and 2 mL of chloroform were added to 20 mg of dried P3HA-1, the obtained sample was sealed, and the sample was heated at 100°C for 140 minutes in a sealed state to obtain a first reaction solution containing methyl ester as a decomposition product of P3HA-1.

[0376] Then, the first reaction liquid was cooled, and 1.5 g of sodium bicarbonate was gradually added to the cooled first reaction liquid for neutralization, and the mixture was left to stand until generation of carbon dioxide stopped, thereby obtaining a second reaction liquid.

[0377] Furthermore, the second reaction liquid and 4 mL of diisopropyl ether were fully mixed to obtain a mixture.

[0378] Next, the mixture was centrifuged to obtain a supernatant.

[0379] Then, the monomer unit composition of the above-mentioned degradation product in the supernatant was analyzed by capillary gas chromatography under the following conditions to determine the content ratio of 3-hydroxybutyrate unit and the content ratio of 3-hydroxyhexanoate (3HH) unit in P3HA-1.

[0380] Gas chromatograph: GC-17A manufactured by Shimadzu Corporation

[0381] Capillary column: NEUTRA BOND-1 manufactured by GL SCIENCES (column length: 25 m, column inner diameter: 0.25 mm, liquid film thickness: 0.4 μm)

[0382] Carrier gas: He

[0383] Column inlet pressure: 100 kPa

[0384] Sample volume: 1 μL

[0385] Regarding the temperature conditions, the temperature was raised at a rate of 8°C / min at 100 to 200°C, and further at a rate of 30°C / min at 200 to 290°C.

[0386] The content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in each of P3HA-2, P3HA-3 and P3HA-4 were determined in the same manner as the content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in P3HA-1.

[0387] In addition, P3HA-2 was separated into a MIBK soluble fraction and a MIBK insoluble fraction by the above-mentioned MIBK separation method. The content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in the MIBK soluble fraction and the MIBK insoluble fraction were determined in the same manner as the content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in P3HA-1.

[0388] (Lubricant)

[0389] BA: Behenamide (also called "Behenamide") (made by Nippon Seika Co., Ltd., BNT-22H)

[0390] EA: Erucic acid amide (made by Nippon Seika Co., Ltd., NEUTRON S)

[0391] (Crystallization nucleating agent)

[0392] PETL: Pentaerythritol (produced by Dacheng Chemicals Co., Ltd., Neulizer P)

[0393] (Examples 1 to 16, 19, 20 and Comparative Examples 1 to 3, 5)

[0394] The above materials were melt-kneaded in accordance with the blending ratios shown in Table 1 below to obtain a raw material composition.

[0395] (Content ratio of each monomer unit in the entire poly(3-hydroxyalkanoate)-based resin)

[0396] The content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate)-based resin contained in the raw material composition is calculated from the content ratio of 3-hydroxybutyrate units in P3HA-1, the content ratio of 3-hydroxybutyrate units in P3HA-2, the content ratio of 3-hydroxybutyrate units in P3HA-3, the content ratio of 3-hydroxybutyrate units in P3HA-4, and the blending ratio of P3HA-1, P3HA-2, P3HA-3 and P3HA-4.

[0397] In addition, the content ratio of the 3-hydroxyhexanoate (3HH) unit in the entire poly(3-hydroxyalkanoate)-based resin contained in the raw material composition is calculated in the same manner.

[0398] It should be noted that the content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate)-based resin contained in the raw material composition also means the content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate)-based resin contained in the melt-blown nonwoven fabric.

[0399] The content ratio of 3-hydroxyhexanoate (3HH) units in the entire poly(3-hydroxyalkanoate)-based resin contained in the raw material composition also means the content ratio of 3-hydroxyhexanoate (3HH) units in the entire poly(3-hydroxyalkanoate)-based resin contained in the meltblown nonwoven fabric.

[0400] The calculated values ​​are shown in Table 1 below.

[0401] (Measurement of physical properties of raw material composition)

[0402] The weight average molecular weight (Mw) and the melt flow rate (MFR) at 165° C. of the raw material composition were measured.

[0403] The measured values ​​are shown in Table 1 below.

[0404] The weight average molecular weight (Mw) of the raw material composition was calculated by GPC measurement. The conditions of GPC measurement are as follows.

[0405] Measuring device: Shimadzu 20A manufactured by Shimadzu Corporation

[0406] Column: Shodex K-806M manufactured by Showa Denko

[0407] Detector: RI detector

[0408] Standard product: Polyethylene

[0409] Eluent: Chloroform (HPLC grade)

[0410] Flow rate: 1mL / min

[0411] Temperature: 40℃

[0412] [Table 1]

[0413]

[0414] use Figures 1 to 3 The melt-blown nonwoven fabric production apparatus shown in was used to produce the first melt-blown nonwoven fabric from the raw material composition under the conditions shown in the following Table 2. In addition, a nozzle with a width of 600 mm was used in the production of the first melt-blown nonwoven fabric.

[0415] Next, using a box-type hot air dryer (manufactured by ESPEC, PH-202), the first meltblown nonwoven fabric was heated according to the heating conditions of Table 2 below, and then naturally cooled at room temperature and pressure (20°C, 1 atmosphere) to obtain meltblown nonwoven fabrics of Examples 1 to 16, 19, 20 and Comparative Examples 1 to 3, 5 as the second meltblown nonwoven fabric.

[0416] (Examples 17, 18 and Comparative Example 4)

[0417] The first melt-blown nonwoven fabrics of Examples 1 and 4 and Comparative Example 1 were used as melt-blown nonwoven fabrics of Examples 17 and 18 and Comparative Example 4, respectively.

[0418]

[0419] (Determination of various physical properties of meltblown nonwoven fabrics)

[0420] The melt-blown nonwoven fabric was measured for its weight per unit area, thickness, average value of fiber diameter among fibers, coefficient of variation of fiber diameter among fibers, and weight average molecular weight (Mw) of the resin composition.

[0421] The measured values ​​are shown in Table 3 below.

[0422] The average value of the fiber diameter in the fibers and the coefficient of variation of the fiber diameter in the fibers were determined using a desktop scanning electron microscope JCM-6000 manufactured by JEOL.

[0423] The weight average molecular weight (Mw) of the resin composition is measured in the same manner as the weight average molecular weight (Mw) of the raw material composition.

[0424] (Maximum load in CD and MD directions of meltblown nonwoven fabrics, tensile elongation at maximum load point and tensile elongation at breaking point)

[0425] For the melt-blown nonwoven fabric, the maximum load in the CD direction and the MD direction, the tensile elongation at the maximum load point, and the tensile elongation at the breaking point were measured.

[0426] It should be noted that the maximum load in the CD direction and the MD direction, the tensile elongation at the maximum load point, and the tensile elongation at the breaking point were measured using a constant rate of extension tensile testing machine in accordance with JIS B7721:2018 “Tensile testing machine / compression testing machine-Calibration method and verification method of force measurement system”.

[0427] As a constant rate elongation type tensile testing machine, a universal testing machine (RTG-1210 manufactured by A&D Corporation) or the like was used.

[0428] First, a test piece (width: 8 mm, length: 40 mm) was cut out from the melt-blown nonwoven fabric.

[0429] Next, the test piece was mounted on a tensile testing machine with an initial load and a clamping interval of 20 mm. In other words, the clamping interval when the initial load was applied to the test piece was set to 20 mm. The initial load was set to a state where the test piece was stretched by hand to a degree that no relaxation occurred.

[0430] Then, the load was increased at a tensile speed of 20 mm / min until the test piece broke, and the maximum loads in the CD direction and the MD direction were measured.

[0431] In addition, the tensile elongation at the maximum load point and the tensile elongation at break in the CD direction and the MD direction were determined by the following formulae.

[0432] Tensile elongation at maximum load point (%) = [(gripping interval at maximum load - gripping interval when initial load is applied to the test piece) / gripping interval when initial load is applied to the test piece] × 100 (%)

[0433] Tensile elongation at break (%) = [(gripping interval at break - gripping interval when initial load is applied to the test piece) / gripping interval when initial load is applied to the test piece] × 100 (%)

[0434] The measured values ​​are shown in Table 3 below.

[0435] (tensile elongation at break in CD direction / tensile elongation at break in MD direction)

[0436] The tensile elongation at break in the CD direction / the tensile elongation at break in the MD direction (CD elongation / MD elongation) was calculated.

[0437] The CD elongation / MD elongation is shown in Table 3 below.

[0438] (Virus droplet capture efficiency, microparticle capture efficiency, and pollen capture efficiency in meltblown nonwoven fabrics)

[0439] For meltblown nonwoven fabrics, the virus droplet capture efficiency (VFE), fine particle capture efficiency (PFE), and pollen capture efficiency were measured. The virus droplet capture efficiency (VFE), fine particle capture efficiency (PFE), and pollen capture efficiency were measured in accordance with JIS T9001:2021 "Performance requirements and test methods for medical masks and general masks".

[0440] It should be noted that the virus droplet capture efficiency refers to the capture efficiency of viruses attached to particles.

[0441] The measured values ​​are shown in Table 3 below.

[0442] (Pressure loss caused by meltblown nonwoven fabric)

[0443] The pressure loss caused by the meltblown nonwoven fabric was measured.

[0444] The pressure loss was measured in accordance with JIS T9001:2021 "Performance requirements and test methods for medical masks and general masks".

[0445] The measured values ​​are shown in Table 3 below.

[0446]

[0447] (How difficult is it to break the meltblown nonwoven fabric and how little fuzzing the meltblown nonwoven fabric has)

[0448] By cutting the meltblown nonwoven fabric, Figure 4 The first test piece is of the shape shown.

[0449] Next, the first test piece was folded in half, and the overlapping portions were melt-bonded (fused) to obtain Figure 5 A second test piece of the shape shown.

[0450] In addition, a mask body including a pair of ear straps and a holding portion capable of holding a mask filter was prepared.

[0451] Then, a mask was produced by inserting the second test piece as a mask filter into the holding portion of the mask body.

[0452] Next, the professional technicians wore the mask for 3 hours and evaluated it according to the following criteria.

[0453] The results are shown in Table 4 below.

[0454] <Degree of resistance to breakage>

[0455] 3: No cracks occurred in the second test piece, and no breakage occurred in the fusion bonded portion of the second test piece.

[0456] 2: A crack smaller than 1 cm occurred on the second test piece, or a break smaller than 1 cm occurred in the fusion bonded portion of the second test piece (the second test piece did not have a crack larger than 1 cm, and the fusion bonded portion of the second test piece did not have a break larger than 1 cm.).

[0457] 1: A crack of 1 cm or more occurred in the second test piece, or a break of 1 cm or more occurred in the fusion bonded portion of the second test piece.

[0458] <Less linting>

[0459] 3: No fuzzing was observed on the second test piece by visual inspection.

[0460] 2: A small amount of fuzz was generated on the second test piece, but it was visually confirmed that no fuzz was attached to the mask body.

[0461] 1: A large amount of fuzz was generated on the second test piece, and adhesion of the fuzz to the mask body was visually confirmed.

[0462] [Table 4]

[0463] Tear resistance Less linting Example 1 3 2 Example 4 3 2 Example 10 3 2 Embodiment 13 3 3 Embodiment 17 2 2 Embodiment 18 2 2 Comparative Example 1 1 1

[0464] As shown in Table 3, in Examples 16, 19, and 20 within the scope of the present invention, the virus droplet capture efficiency (VFE), fine particle capture efficiency (PFE), and pollen capture efficiency are higher than that in Comparative Example 5 in which the average fiber diameter in the fiber is 9.6 μm.

[0465] In addition, as shown in Table 3, Examples 1, 2, 5 to 15, 17, and 18 within the scope of the present invention have higher virus droplet capture efficiency (VFE) and fine particle capture efficiency (PFE) than Comparative Example 5 in which the average fiber diameter in the fiber is 9.6 μm. It should be noted that the pollen capture efficiency was not measured in Examples 1, 2, 5 to 15, 17, and 18.

[0466] Furthermore, as shown in Table 3, the virus droplet collection efficiency (VFE) of Examples 3 and 4 within the scope of the present invention is higher than that of Comparative Example 5 in which the average fiber diameter is 9.6 μm. It should be noted that in Examples 3 and 4, the fine particle collection efficiency (PFE) and pollen collection efficiency were not measured.

[0467] As shown in Tables 1 and 4, the melt-blown nonwoven fabrics of Examples 1, 4, 10, and 13 within the scope of the present invention were less likely to break than Comparative Example 1 in which the content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin was 94.5 mol%.

[0468] As shown in Table 3, compared with Comparative Example 1, Examples 1 to 18 within the scope of the present invention have higher tensile elongation at break in the CD direction and higher tensile elongation at break in the MD direction, and CD elongation / MD elongation is close to 1.00.

[0469] Therefore, it can be inferred that Examples 2, 3, 5 to 9, 11, 12, and 14 to 18 are similar to Examples 1, 4, 10, and 13, and that the meltblown nonwoven fabric is less likely to be broken than Comparative Example 1.

[0470] Therefore, it can be seen that according to the present invention, a melt-blown nonwoven fabric that is not easily broken and has a high particle capturing efficiency can be provided.

[0471] In addition, as shown in Table 3, the virus droplet capture efficiency (VFE) and fine particle capture efficiency (PFE) of Examples 1, 2, 5 to 15, 17, and 18, in which the average fiber diameter in the fiber is 5.0 μm or less, are further improved compared to Example 20, in which the average fiber diameter in the fiber is 6.1 μm. It should be noted that the pollen capture efficiency was not measured in Examples 1, 2, 5 to 15, 17, and 18.

[0472] In addition, as shown in Table 3, the virus droplet capture efficiency (VFE) of Examples 3 and 4, in which the average fiber diameter in the fiber is 5.0 μm or less, is further improved compared to Example 20, in which the average fiber diameter in the fiber is 6.1 μm. It should be noted that in Examples 3 and 4, the fine particle capture efficiency (PFE) and pollen capture efficiency were not measured.

[0473] In addition, as shown in Table 3, the pollen collection efficiency of Examples 16 and 19 in which the average fiber diameter in the fiber is less than 5.0 μm and that of Example 20 in which the average fiber diameter in the fiber is 6.1 μm are at the same level, but compared with Example 20, the virus droplet collection efficiency (VFE) and fine particle collection efficiency (PFE) of Examples 16 and 19 are further improved.

[0474] This shows that it is possible to provide a melt-blown nonwoven fabric having a further improved particle collection efficiency by setting the average fiber diameter of the fibers of the melt-blown nonwoven fabric to 5.0 μm or less.

[0475] In addition, as shown in Table 3, the virus droplet capture efficiency (VFE) and fine particle capture efficiency (PFE) of Examples 1, 2, 6 to 15, 17, and 18, in which the average fiber diameter in the fiber is 3.0 μm or less, are further improved compared to Example 19, in which the average fiber diameter in the fiber is 3.3 μm. It should be noted that the pollen capture efficiency was not measured in Examples 1, 2, 6 to 15, 17, and 18.

[0476] In addition, as shown in Table 3, in Examples 3 and 4 where the average fiber diameter in the fibers was 3.0 μm or less, the virus droplet capture efficiency (VFE) was further improved compared to Example 19 where the average fiber diameter in the fibers was 3.3 μm. It should be noted that in Examples 3 and 4, the fine particle capture efficiency (PFE) and pollen capture efficiency were not measured.

[0477] In addition, as shown in Table 3, the fine particle capture efficiency (PFE) of Example 5, in which the average fiber diameter in the fiber is 3.0 μm or less, and that of Example 19, in which the average fiber diameter in the fiber is 3.3 μm, are at the same level, but the virus droplet capture efficiency (VFE) of Example 5 is further improved compared to Example 19. It should be noted that the pollen capture efficiency was not measured in Example 5.

[0478] In addition, as shown in Table 3, Example 16 in which the average fiber diameter in the fiber is less than 3.0 μm has the same level of fine particle capture efficiency (PFE) and pollen capture efficiency as Example 19 in which the average fiber diameter in the fiber is 3.3 μm, but the virus droplet capture efficiency (VFE) of Example 16 is further improved compared to Example 19.

[0479] Therefore, it can be seen that a melt-blown nonwoven fabric having a further improved particle collection efficiency can be provided by setting the average value of the fiber diameter in the fibers of the melt-blown nonwoven fabric to 3.0 μm or less.

[0480] In addition, as shown in Tables 3 and 4, the meltblown nonwoven fabrics of Examples 1, 2, 6 to 15 in which the tensile elongation at break in the MD direction of the meltblown nonwoven fabric is 120% or more and the tensile elongation at break in the CD direction of the meltblown nonwoven fabric is 120% or more are less likely to break, compared with Examples 17 and 18 in which the tensile elongation at break in the MD direction of the meltblown nonwoven fabric is 115% or less.

[0481] Therefore, it is understood that the meltblown nonwoven fabric becomes less likely to break when the tensile elongation at break in the MD direction of the meltblown nonwoven fabric is 120% or more and the tensile elongation at break in the CD direction of the meltblown nonwoven fabric is 120% or more.

[0482] Furthermore, as shown in Table 4, in Example 1 in which the second melt-blown nonwoven fabric was obtained by heating the first melt-blown nonwoven fabric, which was the nonwoven fabric of Example 17, the melt-blown nonwoven fabric was less likely to be broken than in Example 17.

[0483] As shown in Table 4, in Example 4 in which the second melt-blown nonwoven fabric was obtained by heating the first melt-blown nonwoven fabric, which was the nonwoven fabric of Example 18, the melt-blown nonwoven fabric was less likely to be broken than in Example 18.

[0484] Therefore, it can be seen that heating the melt-blown nonwoven fabric makes the melt-blown nonwoven fabric less likely to break.

[0485] In addition, as shown in Table 3, compared with Example 17, in Example 1 in which the second meltblown nonwoven fabric was obtained by heating the first meltblown nonwoven fabric serving as the nonwoven fabric of Example 17, the tensile elongation at break at the MD direction of the meltblown nonwoven fabric and the tensile elongation at break at the CD direction of the meltblown nonwoven fabric were increased.

[0486] In addition, as shown in Table 3, compared with Example 18, in Example 4 in which the second meltblown nonwoven fabric was obtained by heating the first meltblown nonwoven fabric serving as the nonwoven fabric of Example 18, the tensile elongation at break at the MD direction of the meltblown nonwoven fabric and the tensile elongation at break at the CD direction of the meltblown nonwoven fabric were high.

[0487] Therefore, it is understood that heating the melt-blown nonwoven fabric increases the tensile elongation at break in the MD direction of the melt-blown nonwoven fabric and the tensile elongation at break in the CD direction of the melt-blown nonwoven fabric.

[0488] In addition, as shown in Table 3, compared with Example 17, in Example 1, in which the second meltblown nonwoven fabric was obtained by heating the first meltblown nonwoven fabric which is the nonwoven fabric of Example 17, the tensile elongation at break in the CD direction and the tensile elongation at break in the MD direction were high.

[0489] In addition, as shown in Table 3, compared with Example 18, in Example 4, in which the second meltblown nonwoven fabric was obtained by heating the first meltblown nonwoven fabric which is the nonwoven fabric of Example 18, the tensile elongation at break in the CD direction and the tensile elongation at break in the MD direction were high.

[0490] Therefore, it can be seen that the tensile elongation at break in the CD direction and the tensile elongation at break in the MD direction of the melt-blown nonwoven fabric can be increased by heating the melt-blown nonwoven fabric.

[0491] Furthermore, as shown in Tables 1 and 4, the meltblown nonwoven fabrics of Examples 1, 4, 10, 13, 17, and 18 within the scope of the present invention had less fuzzing than Comparative Example 1 in which the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin was 94.5 mol%.

Claims

1. A meltblown nonwoven fabric comprising fibers, wherein: The fiber is formed from a resin composition containing a poly(3-hydroxyalkanoate) resin. The poly(3-hydroxyalkanoate)-based resin comprises a copolymer having a 3-hydroxybutyrate unit, The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin is 80.0 mol% or more and 93.5 mol% or less, In the fibers, the average value of the fiber diameter is 8.0 μm or less.

2. The meltblown nonwoven fabric according to claim 1, wherein: The average value of the fiber diameter is 5.0 μm or less.

3. The meltblown nonwoven fabric according to claim 2, wherein: The average value of the fiber diameter is 3.0 μm or less.

4. The melt-blown nonwoven fabric according to any one of claims 1 to 3, wherein The unit area weight of the meltblown nonwoven fabric is 20 to 80 g / m 2 .

5. The melt-blown nonwoven fabric according to any one of claims 1 to 3, wherein The weight average molecular weight of the resin composition is 100,000 to 250,000.

6. The melt-blown nonwoven fabric according to any one of claims 1 to 3, wherein The tensile elongation at break of the meltblown nonwoven fabric in the MD direction is greater than 50%. The tensile elongation at break of the meltblown nonwoven fabric in the CD direction is greater than 50%.

7. The melt-blown nonwoven fabric according to any one of claims 1 to 3, wherein The ratio of the tensile elongation at break in the CD direction of the melt-blown nonwoven fabric to the tensile elongation at break in the MD direction of the melt-blown nonwoven fabric is 0.50 to 2.

00.

8. The melt-blown nonwoven fabric according to any one of claims 1 to 3, wherein The poly(3-hydroxyalkanoate)-based resin includes a poly(3-hydroxyalkanoate)-based resin component having a 3-hydroxybutyrate unit content ratio of 76 mol % or less.

9. A laminate comprising a first nonwoven fabric and a second nonwoven fabric laminated on at least one side of the first nonwoven fabric, wherein: The first nonwoven fabric is the meltblown nonwoven fabric according to claim 1, The second nonwoven fabric is a nonwoven fabric containing cellulose fibers. 10 . A mask filter, comprising the melt-blown nonwoven fabric according to claim 1 or the laminate according to claim 9 .

11. A mask comprising a mask body and the mask filter according to claim 10.

Images