WO2024005145A1

WO2024005145A1 - Nonwoven fabric and production method therefor

Info

Publication number: WO2024005145A1
Application number: PCT/JP2023/024191
Authority: WO
Inventors: 仁志島本; 貴幸宮本; 武和前田; 正信田村; 俊介大谷
Original assignee: 株式会社カネカ
Priority date: 2022-06-30
Filing date: 2023-06-29
Publication date: 2024-01-04

Abstract

The present invention provides a nonwoven fabric that is difficult to tear. The present invention is a nonwoven fabric comprising fibers, wherein: the fibers are formed from a resin composition containing a poly(3-hydroxyalkanoate)-based resin; the poly(3-hydroxyalkanoate)-based resin contains a copolymer that has a 3-hydroxybutyrate unit; the content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate)-based resin included in the nonwoven fabric is 70.0-92.0 mol%; the tensile elongation at break point in the MD of the nonwoven fabric is not less than 100%; and the tensile elongation at break point in the CD of the nonwoven fabric is not less than 100%.

Description

Nonwoven fabric and its manufacturing method

The present invention relates to a nonwoven fabric and a method for manufacturing the same.

Nonwoven fabrics are used, for example, as base materials for various products (eg, masks, filters, disposable diapers, sanitary napkins, taping materials, patches, wrapping bags, gloves, clothing, etc.).
As the fibers of the nonwoven fabric, fibers containing poly(3-hydroxyalkanoate) resin, which is a biodegradable resin, are used from the viewpoint of suppressing the burden on the global environment (for example, Patent Document 1).

International Publication No. 2019/142920

Although nonwoven fabrics are required to be resistant to tearing, sufficient studies have not been made on nonwoven fabrics that are resistant to tearing.

Therefore, an object of the present invention is to provide a nonwoven fabric that is hard to tear.

The first aspect of the present invention is a nonwoven fabric containing fibers,
The fiber is formed from a resin composition containing a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 70.0 mol% or more and 92.0 mol% or less,
The nonwoven fabric has a tensile elongation at break in the MD direction of 100% or more,
The present invention relates to a nonwoven fabric having a tensile elongation at break in the CD direction of the nonwoven fabric of 100% or more.

The second aspect of the present invention is a method for producing a nonwoven fabric, which includes producing a nonwoven fabric containing fibers using a nozzle having a nozzle hole.
a step (A) of obtaining a raw yarn by discharging the melt from the nozzle hole;
and a step (B) of stretching the yarn,
The melt contains a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less,
The present invention relates to a method for producing a meltblown nonwoven fabric, wherein the ratio of the opening area of the nozzle holes to the cross-sectional area of the fibers is 300 or more.

The third aspect of the present invention is a method for producing a nonwoven fabric, which includes producing a nonwoven fabric containing fibers using a nozzle having a nozzle hole.
a step (A) of obtaining a raw yarn by discharging the melt from the nozzle hole;
and a step (B) of stretching the yarn,
The raw material composition contains a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less,
The present invention relates to a method for producing a spunbond nonwoven fabric, wherein the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is 150 or more.

According to the present invention, a tear-resistant nonwoven fabric can be provided.

A schematic diagram of a nonwoven fabric manufacturing device. A schematic perspective view of a nozzle. A schematic cross-sectional view of a nozzle hole and a conveyor belt. Photographs of the two first specimens. Photo of mask.

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

<Nonwoven fabric>
First, the nonwoven fabric according to this embodiment will be explained.
The nonwoven fabric according to this embodiment includes fibers.
The fibers are made of a resin composition containing a poly(3-hydroxyalkanoate) resin.
The poly(3-hydroxyalkanoate) resin includes a copolymer having 3-hydroxybutyrate units.
The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 70.0 mol% or more and 92.0 mol% or less.
The tensile elongation at break in the MD direction of the nonwoven fabric is 100% or more.
The nonwoven fabric has a tensile elongation at break in the CD direction of 100% or more.

The resin composition contains a polymer component. Moreover, the resin composition may further contain an additive.

The polymer component contains a poly(3-hydroxyalkanoate) resin.
The polymer component may contain other polymers in addition to the poly(3-hydroxyalkanoate) resin.

The poly(3-hydroxyalkanoate) resin is a polyester containing 3-hydroxyalkanoic acid as a monomer.
That is, the poly(3-hydroxyalkanoate) resin is a resin containing 3-hydroxyalkanoic acid as a structural unit.
Further, the poly(3-hydroxyalkanoate) resin is a biodegradable polymer.
Note that "biodegradability" in this embodiment refers to a property that can be decomposed into low molecular weight compounds by microorganisms in the natural world. Specifically, we use ISO 14855 (compost) and ISO 14851 (activated sludge) for aerobic conditions, and ISO 14853 (aqueous phase) and ISO 15985 (solid phase) for anaerobic conditions. The presence or absence of degradability can be determined. Furthermore, the degradability of microorganisms in seawater can be evaluated by measuring biochemical oxygen demand.

The poly(3-hydroxyalkanoate) resin includes a copolymer having 3-hydroxybutyrate units.

In the copolymer having 3-hydroxybutyrate units, monomer units other than 3-hydroxybutyrate units include, for example, hydroxyalkanoate units other than 3-hydroxybutyrate units.
Examples of hydroxyalkanoate units other than 3-hydroxybutyrate units include 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxyoctadecanoate, 3-hydroxyvalerate, and 4-hydroxybutyrate. Examples include.

Copolymers having 3-hydroxybutyrate units include P3HB3HH, P3HB3HV, P3HB4HB, poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3- Hydroxyoctadecanoate) and the like.
Here, P3HB3HH means poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).
P3HB3HV means poly(3-hydroxybutyrate-co-3-hydroxyvalerate).
P3HB4HB means poly(3-hydroxybutyrate-co-4-hydroxybutyrate).
The poly(3-hydroxyalkanoate) resin may contain only one type of copolymer having 3-hydroxybutyrate units, or may contain two or more types.
As the copolymer having 3-hydroxybutyrate units, P3HB3HH is preferred.

The resin composition preferably contains a copolymer having 3-hydroxybutyrate units in an amount of 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more.

The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 70.0 mol% or more and 92.0 mol% or less, preferably 80.0 mol% or more. It is 92.0 mol % or less, more preferably 82.0 mol or more and 92.0 mol or less, still more preferably 85.0 mol or more and 91.6 mol or less.
When the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 70.0 mol% or more, the rigidity of the fiber becomes high.
When the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 92.0 mol% or less, the nonwoven fabric according to the present embodiment becomes difficult to tear. Further, since the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 92.0 mol% or less, the nonwoven fabric according to the present embodiment does not have fuzz. Less likely to occur.
The content ratio of the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is the same as that of the 3-hydroxybutyrate unit in the entire poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric. It means the content ratio of 3-hydroxybutyrate units.

The content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric can be determined as follows.
First, a sample was prepared by adding 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 to 20 mg of the dried poly(3-hydroxyalkanoate) resin of the nonwoven fabric. The first reaction solution containing methyl ester, which is a decomposition product of poly(3-hydroxyalkanoate)-based resin, is obtained by sealing the sample and heating the sample at 100° C. for 140 minutes in the sealed state.
Then, the first reaction liquid is cooled, 1.5 g of sodium hydrogen carbonate is added little by little to the cooled first reaction liquid to neutralize it, and the second reaction liquid is left to stand until the generation of carbon dioxide gas stops. A reaction solution is obtained.
Furthermore, a mixture is obtained by thoroughly mixing the second reaction solution and 4 mL of diisopropyl ether.
Next, the mixture is centrifuged to obtain a supernatant.
Then, the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate)-based resin is determined by analyzing the monomer unit composition of the decomposed product in the supernatant liquid by capillary gas chromatography under the following conditions. .
Gas chromatograph: GC-17A manufactured by Shimadzu Corporation
Capillary column: NEUTRA BOND-1 manufactured by GL Science (column length: 25 m, column inner diameter: 0.25 mm, liquid film thickness: 0.4 μm)
Carrier gas: He
Column inlet pressure: 100kPa
Sample amount: 1μL
Regarding the temperature conditions, the temperature is raised at a rate of 8°C/min from 100 to 200°C, and further at a rate of 30°C/min from 200 to 290°C.

In addition, the content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition (the "raw material composition" will be described later) is determined by It may also be the content ratio of 3-hydroxybutyrate units in the (3-hydroxyalkanoate)-based resin.
The content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition is determined by using the dried poly(3-hydroxyalkanoate) resin of the raw material composition, It can be determined in the same manner as the above-mentioned "content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric."

From the viewpoint of improving the mechanical properties of the nonwoven fabric, the poly(3-hydroxyalkanoate) resin has a content of 3-hydroxybutyrate units of 76 mol% or less. It is preferable to include the following components.
The content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin component is 0 to 76 mol%, preferably 1 to 76 mol%, and more preferably 50 to 76 mol%. Examples of the poly(3-hydroxyalkanoate) resin component include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), etc. is preferred.

(MIBK fractionation method)
The fact that the poly(3-hydroxyalkanoate)-based resin contains the poly(3-hydroxyalkanoate)-based resin component can be achieved by, for example, a solvent fractionation method using the difference in solubility in methyl isobutyl ketone (MIBK). (Also referred to as "MIBK fractionation method.")
That is, poly(3-hydroxyalkanoate)-based resin is fractionated into an MIBK-soluble fraction and an MIBK-insoluble fraction by the MIBK fractionation method, and the content ratio of 3-hydroxybutyrate units in either fraction is 76. If the amount is mol % or less, it can be confirmed that the poly(3-hydroxyalkanoate)-based resin contains the poly(3-hydroxyalkanoate)-based resin component.

The specific fractionation procedure is described below. First, measure approximately 100 mg of poly(3-hydroxyalkanoate) resin into a screw cap test tube, add 10 ml of MIBK, and close the cap. Thereafter, the mixture is heated at 140° C. for about 1 to 3 hours with shaking to completely dissolve the poly(3-hydroxyalkanoate) resin. After complete dissolution, leave the solution at 25° C. for 1 minute to lower the temperature below the boiling point, immediately transfer all the dissolved solution to a pre-weighed centrifuge tube, and close the cap. The capped centrifuge tube is left at 25° C. for an additional 15 minutes to precipitate a portion of the lysate. The precipitate and the solution are separated by centrifugation (9000 rpm, 5 minutes), and all the solution is transferred to an aluminum cup whose weight has been measured in advance. Add 10 ml of MIBK to the centrifuge tube in which the precipitate remains, mix with a vortex mixer, centrifuge again (9000 rpm, 5 minutes), and transfer the solution to the aluminum cup containing the solution. The aluminum cup is heated at 120° C. for 30 minutes to volatilize MIBK and precipitate the melt. Further, the precipitate remaining in the aluminum cup and the precipitate remaining in the centrifuge tube are each vacuum-dried at 100° C. for 6 hours. The precipitate remaining in the aluminum cup is weighed as the MIBK-soluble fraction, and the precipitate remaining in the centrifuge tube is weighed as the MIBK-insoluble fraction. Confirm that the difference between the total weight of the MIBK soluble fraction and the MIBK insoluble fraction and the initially measured weight of the poly(3-hydroxyalkanoate) resin is within ±3%.

The content ratio of 3-hydroxybutyrate units in each of the MIBK soluble fraction and MIBK insoluble fraction can be measured by the method described above.
The content of 3-hydroxybutyrate units in either the MIBK-soluble fraction or the MIBK-insoluble fraction is preferably 0 to 76 mol%, more preferably 1 to 76 mol%, and still more preferably 50 to 76 mol%. It is 76 mol%.

Examples of poly(3-hydroxyalkanoate) resins other than copolymers having 3-hydroxybutyrate units include P3HB, poly(3-hydroxyvalerate), poly(3-hydroxyhexanoate), etc. Can be mentioned.
Here, P3HB means poly(3-hydroxybutyrate) which is a homopolymer.

Note that P3HB has a function of promoting crystallization of P3HB itself and poly(3-hydroxyalkanoate) resins other than P3HB.

It is preferable that the other polymer is biodegradable.

Examples of other biodegradable polymers include polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene succinate, polyvinyl alcohol, polyglycolic acid, unmodified starch, Examples include modified starch, cellulose acetate, chitosan, and the like.
The polycaprolactone is a polymer obtained by ring-opening polymerization of ε-caprolactone.
The resin composition may contain one type of other polymer, or may contain two or more types of other polymers.

Since the nonwoven fabric according to this embodiment contains a biodegradable polymer, even if the nonwoven fabric is discarded in the environment, it is easily decomposed in the environment, so that the load on the environment can be suppressed. .

The resin composition may further contain an additive.

Examples of additives include crystal nucleating agents, lubricants, stabilizers (antioxidants, ultraviolet absorbers, etc.), colorants (dyes, pigments, etc.), plasticizers, inorganic fillers, organic fillers, antistatic agents, etc. can be mentioned.

The resin composition preferably contains a crystal nucleating agent as an additive.
The crystal nucleating agent is a compound that can promote crystallization of poly(3-hydroxyalkanoate) resin. Further, the crystal nucleating agent has a higher melting point than the poly(3-hydroxyalkanoate) resin.
By containing a crystal nucleating agent in the resin composition, crystallization of the poly(3-hydroxyalkanoate) resin is promoted and adjacent fibers become difficult to fuse together when producing a nonwoven fabric. As a result, it becomes easier to reduce the coefficient of variation of the fiber diameter in the fiber.
Examples of the crystal nucleating agent include inorganic substances (e.g., boron nitride, titanium oxide, talc, layered silicates, calcium carbonate, sodium chloride, metal phosphates, etc.); sugar alcohol compounds derived from natural products (e.g., pentane, etc.); Erythritol, erythritol, galactitol, mannitol, arabitol, etc.); polyvinyl alcohol; chitin; chitosan; polyethylene oxide; aliphatic carboxylate; aliphatic alcohol; aliphatic carboxylic acid ester; dicarboxylic acid derivative (e.g. dimethyl adipate, dibutyl adipate) , diisodecyl adipate, dibutyl sebacate, etc.); cyclic compounds having in the molecule C=O and a functional group selected from NH, S, and O (e.g., indigo, quinacridone, quinacridone magenta, etc.); sorbitol derivatives (e.g., (bisbenzylidene sorbitol, bis(p-methylbenzylidene) sorbitol, etc.); Compounds containing a nitrogen-containing heteroaromatic nucleus (e.g., pyridine ring, triazine ring, imidazole ring, etc.) (e.g., pyridine, triazine, imidazole, etc.); Phosphoric acid Examples include ester compounds; bisamides of higher fatty acids; metal salts of higher fatty acids; and branched polylactic acids.
Note that P3HB, which is the poly(3-hydroxyalkanoate) resin, can also be used as a crystal nucleating agent.
These may be used alone or in combination of two or more.

As the crystal nucleating agent, from the viewpoint of improving the crystallization rate of the poly(3-hydroxyalkanoate)-based resin, and from the viewpoint of compatibility and affinity with the poly(3-hydroxyalkanoate)-based resin, Sugar alcohol compounds, polyvinyl alcohol, chitin, and chitosan are preferred.
Furthermore, among the sugar alcohol compounds, pentaerythritol is preferred.

The crystal nucleating agent preferably has a crystal structure at room temperature (25° C.).
Since the crystal nucleating agent has a crystal structure at room temperature (25° C.), there is an advantage that crystallization of the poly(3-hydroxyalkanoate) resin is further promoted.
Further, the crystal nucleating agent having a crystal structure at room temperature (25°C) is preferably in a powder form at room temperature (25°C).
Furthermore, the average particle diameter of the crystal nucleating agent that is in powder form at room temperature (25° C.) is preferably 10 μm or less.

The resin composition preferably contains 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and still more preferably 0. Contains .5 parts by mass or more.
When the resin composition contains 0.1 parts by mass or more of a crystal nucleating agent based on 100 parts by mass of poly(3-hydroxyalkanoate) resin, poly(3-hydroxyalkanoate) can be used when producing a nonwoven fabric. ) has the advantage that the crystallization of the resin is more easily promoted.
Further, the resin composition preferably contains a crystal nucleating agent at 2.5 parts by mass or less, more preferably at most 2.0 parts by mass, based on 100 parts by mass of the poly(3-hydroxyalkanoate) resin.
When the resin composition contains 2.5 parts by mass or less of a crystal nucleating agent per 100 parts by mass of poly(3-hydroxyalkanoate) resin, the advantage is that fibers can be easily obtained when producing a nonwoven fabric. There is.
In addition, since P3HB is a poly(3-hydroxyalkanoate)-based resin and can also function as a crystal nucleating agent, when the resin composition contains P3HB, the amount of P3HB is It is included in both the amount of the hydroxyalkanoate (hydroxyalkanoate) resin and the amount of the crystal nucleating agent.

It is preferable that the resin composition contains the lubricant.
When producing a nonwoven fabric, the presence of a lubricant in the fibers improves the lubricity of the fibers, making it possible to suppress fusion between the fibers.
On the other hand, when the resin composition does not contain a lubricant or contains a very small amount of a lubricant, there are advantages such as improved tape adhesion of the nonwoven fabric and ease of handling in the process of manufacturing the nonwoven fabric. be.
Whether or not a lubricant is added and the amount thereof can be determined as appropriate depending on the intended use of the nonwoven fabric (for example, melt-blown nonwoven fabric).
Examples of the lubricant include compounds having an amide bond.
The compound having an amide bond preferably contains one or more selected from lauric acid amide, myristic acid amide, stearic acid amide, behenic acid amide, and erucic acid amide.

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 even more preferably 0.5 parts by mass or more, based on 100 parts by mass of the polymer component. When the content of the lubricant in the resin composition is 0.05 parts by mass or more per 100 parts by mass of the polymer component, there is an advantage that fusion between fibers can be further suppressed when producing a nonwoven fabric. be.
On the other hand, when the content of the lubricant in the resin composition is 0 to 0.2 parts by mass based on 100 parts by mass of the polymer component, the tape adhesion of the nonwoven fabric improves, making it easier to handle during the manufacturing process of the nonwoven fabric. This has the advantage that it is easy to do.
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, even more preferably 8 parts by mass or less, and most preferably 5 parts by mass or less, based on 100 parts by mass of the polymer component. . When the content of the lubricant in the resin composition is 12 parts by mass or less per 100 parts by mass of the polymer component, there is an advantage that the lubricant can be prevented from bleeding out onto the surface of the fibers.

The melt mass flow rate (MFR) of the resin composition at 165° C. is preferably 20 to 1500 g/10 min, more preferably 30 to 1500 g/10 min, even more preferably 40 to 1300 g/10 min, particularly preferably 50 to 1200 g/10 min. It is 10 minutes.

When the melt mass flow rate at 165° C. of the resin composition in the fiber is 1500 g/10 min or less, the strength and elongation of the nonwoven fabric are increased.
By having a melt mass flow rate at 165° C. of the resin composition in the fibers of 20 g/10 min or more, the tension applied to the raw yarn (the “raw yarn” will be described later) can be lowered when the yarn is drawn. This makes it easier to reduce the fiber diameter of the fibers in the resulting nonwoven fabric. As a result, it becomes easier to increase the efficiency of particle collection by the nonwoven fabric.
Further, since the melt mass flow rate at 165° C. of the resin composition in the fiber is 20 g/10 min or more, it is possible to suppress the formation of lumps of polymer components when producing a nonwoven fabric. As a result, the productivity of nonwoven fabrics is improved. Further, since the melt mass flow rate at 165° C. of the resin composition in the fiber is 20 g/10 min or more, the nozzle hole of the nozzle (the “nozzle hole” will be described later) is used when producing the nonwoven fabric. ) clogging can be suppressed. As a result, the productivity of nonwoven fabrics is improved.

Regarding the melt mass flow rate (MFR) of the resin composition at 165°C, the melt volume flow rate (MFR) of the resin composition at 165°C is determined by method B of ASTM-D1238 (ISO1133-1, JIS K7210-1:2011). The melt mass flow rate (MFR) of the resin composition at 165°C is determined from the melt volume flow rate (MVR) of the resin composition at 165°C and the density of the resin composition.
Further, the melt volume flow rate (MVR) at 165° C. of the resin composition 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.

The weight average molecular weight of the resin composition is preferably 50,000 to 350,000, more preferably 70,000 to 300,000, even more preferably 80,000 to 250,000, particularly preferably 150,000 to 250. ,000.

When the weight average molecular weight of the resin composition in the fiber is 50,000 or more, the strength and elongation of the nonwoven fabric are increased.
Further, since the weight average molecular weight of the resin composition in the fiber is 150,000 or more, the nonwoven fabric becomes even more difficult to tear.
When the weight average molecular weight of the resin composition in the fiber is 350,000 or less, the tension applied to the yarn during drawing can be lowered, making it easier to reduce the fiber diameter of the fibers in the resulting nonwoven fabric. As a result, it becomes easier to increase the efficiency of particle collection by the nonwoven fabric.
Further, since the weight average molecular weight of the resin composition in the fiber is 350,000 or less, it is possible to suppress the formation of lumps of polymer components when producing a nonwoven fabric. As a result, the productivity of nonwoven fabrics is improved. Furthermore, since the weight average molecular weight of the resin composition in the fiber is 350,000 or less, the nozzle hole of the nozzle (the "nozzle hole" will be described later) is prevented from clogging when producing a nonwoven fabric. It can be suppressed. As a result, the productivity of nonwoven fabrics is improved.

Note that the weight average molecular weight in this embodiment is measured from 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 molecular weight may be used.

The average fiber diameter of the fibers is preferably 30.0 μm or less, more preferably 25.0 μm or less, even more preferably 20.0 μm or less, even more preferably 0.50 to 20.0 μm, particularly preferably 0.0 μm or less. It is 80 to 15.0 μm, most preferably 1.0 to 15.0 μm.
The coefficient of variation of the fiber diameter of the fiber is preferably 0.40 or less, more preferably 0.36 or less, and even more preferably 0.32 or less. Further, the coefficient of variation of the fiber diameter of the fiber is, for example, 0.10 or more.

When the average fiber diameter of the fibers is 20.0 μm or less, the efficiency of particle collection by the nonwoven fabric increases.
Further, by setting the average fiber diameter of the fibers to 20.0 μm or less, the stiffness of the fibers can be lowered, and as a result, the texture (for example, texture, touch, etc.) of the nonwoven fabric is improved.
When the average fiber diameter of the fibers is 0.50 μm or more, the strength and elongation of the nonwoven fabric are increased.
When the coefficient of variation of the fiber diameter of the fibers is 0.40 or less, the number of extremely thick fibers is reduced, and as a result, the efficiency of particle collection by the nonwoven fabric is increased. Further, since the coefficient of variation of the fiber diameter of the fibers is 0.40 or less, the number of extremely thin fibers is reduced, and as a result, the strength and elongation of the nonwoven fabric are increased.

Note that the average value and coefficient of variation of the fiber diameter of the fibers can be determined as follows.
First, a test piece is obtained from a nonwoven fabric.
Next, photographs (1700x) are taken at five locations on the surface of the test piece using a scanning electron microscope.
Then, the diameter (width) of 20 or more randomly selected fibers for each photograph is measured.
Next, the arithmetic mean value and coefficient of variation (=standard deviation/arithmetic mean value) are determined from the diameter (width) values of all the measured fibers.

The basis weight of the nonwoven fabric according to this embodiment is preferably 20 to 150 g/m ² , more preferably 30 to 140 g/m ² , and still more preferably 40 to 120 g/m ² .
When the basis weight of the nonwoven fabric according to this embodiment is 20 g/m ² or more, the strength and elongation of the nonwoven fabric are increased. Further, since the nonwoven fabric according to the present embodiment has a basis weight of 20 g/m ² or more, the particle collection efficiency of the nonwoven fabric increases.
Further, by setting the basis weight of the nonwoven fabric according to the present embodiment to 150 g/m ² or less, liquid permeability (water permeability, etc.) or air permeability can be improved.

Note that the basis weight of the nonwoven fabric according to this embodiment can be determined as follows.
First, a test piece is obtained from the nonwoven fabric according to this embodiment.
The size of the test piece can be, for example, 100 mm x 100 mm, 200 mm x 200 mm, etc.
Next, the weight of the test piece is measured using an electronic balance or the like.
Then, the basis weight is calculated by dividing the weight of the test piece by the area of the test piece.

Further, the thickness of the nonwoven fabric according to this embodiment is preferably 0.10 to 0.80 mm, more preferably 0.15 to 0.60 mm.
Since the thickness of the nonwoven fabric according to this embodiment is 0.10 to 0.80 mm, it becomes easier to obtain a homogeneous nonwoven fabric when producing the nonwoven fabric.
Further, since the thickness of the nonwoven fabric according to this embodiment is 0.10 mm or more, the strength and elongation of the nonwoven fabric are increased. Further, since the thickness of the nonwoven fabric according to the present embodiment is 0.10 mm or more, the efficiency of collecting particles by the nonwoven fabric increases.
Furthermore, since the thickness of the nonwoven fabric according to this embodiment is 0.80 mm or less, the liquid permeability (water permeability, etc.) or air permeability of the nonwoven fabric can be improved.

In addition, regarding the thickness of the nonwoven fabric according to the present embodiment, the thickness of the nonwoven fabric at three or more locations can be measured using a thickness meter, and the arithmetic mean value thereof can be taken as the thickness of the nonwoven fabric.
Examples of the thickness gauge include "PEACOCK" manufactured by Ozaki Seisakusho Co., Ltd.

Furthermore, the average pore diameter of the nonwoven fabric according to the present embodiment is preferably 2.5 μm or more and 30.0 μm or less, more preferably 3.0 μm or more and 25.0 μm or less, and still more preferably 3.0 μm or more and 20.0 μm or less.
When the average pore diameter of the nonwoven fabric according to this embodiment is 2.5 μm or more, the liquid permeability (water permeability, etc.) or air permeability of the nonwoven fabric can be improved.
When the average pore diameter of the nonwoven fabric according to this embodiment is 30.0 μm or less, the efficiency of particle collection by the nonwoven fabric increases.

The average pore diameter of the nonwoven fabric according to the present embodiment is the average flow pore diameter determined according to JIS K3832-1990 "Bubble point test method for microfiltration membrane elements and modules."
The average flow pore diameter can be measured using, for example, a palm porometer (manufactured by PMI).

The tensile elongation at break in the MD direction of the nonwoven fabric according to the present embodiment (also simply referred to as "MD elongation") is 100% or more, preferably 120% or more, and more preferably 150% or more. The MD elongation of the nonwoven fabric according to this embodiment is, for example, 800% or less.
When the MD elongation is 100% or more, the nonwoven fabric according to the present embodiment is difficult to tear even when stretched in the MD direction.
By controlling the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin to 92.0 mol% or less, the MD elongation can be easily increased.

The tensile elongation at break in the CD direction (also simply referred to as "CD elongation") of the nonwoven fabric according to the present embodiment is 100% or more, preferably 120% or more, and more preferably 150% or more. The CD elongation of the nonwoven fabric according to this embodiment is, for example, 800% or less.
When the CD elongation is 100% or more, the nonwoven fabric according to the present embodiment is difficult to tear even when stretched in the CD direction.
By controlling the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin to 92.0 mol% or less, the CD elongation can be easily increased.

Here, the MD direction is a direction (Machine Direction) in which the nonwoven fabric moves when manufacturing the nonwoven fabric.
The CD direction is a direction perpendicular to the MD direction.
Tensile elongation at break is also called tensile elongation at break.

The ratio of the tensile elongation at break in the CD direction of the nonwoven fabric to the tensile elongation at break in the MD direction of the nonwoven fabric (CD elongation/MD elongation) is preferably 0.50 to 2.00, more preferably It is 0.56 to 1.80.
Since the CD elongation/MD elongation is 0.50 to 2.00, when stress is applied to the nonwoven fabric according to this embodiment, stress is applied only in either the CD direction or the MD direction. Concentration is suppressed, and as a result, the nonwoven fabric becomes difficult to tear.
By controlling the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin to 92.0 mol% or less, a CD elongation/MD elongation of 0.50 to 2.00 can be obtained. It will be easier to fall within the range.

In addition, the tensile elongation at break can be measured using a constant speed extension type tensile testing machine that complies with JIS B7721:2018 "Tensile testing machine/compression testing machine - Calibration method and verification method of force measurement system". . As the constant speed extension type tensile testing machine, a universal testing machine (RTG-1210 manufactured by A&D Co., Ltd.) or the like can be used.
Specifically, the tensile elongation at break can be determined as follows.
First, a test piece (width: 8 mm, length: 40 mm) is cut out from a nonwoven fabric.
Next, the test piece is attached to a constant speed extension type tensile tester with an initial load at a grip interval of 20 mm. In other words, the gripping interval when the initial load is applied to the test piece is 20 mm. However, for the initial load, the test piece should be pulled by hand to the extent that no slack occurs.
Then, a load is applied at a tensile speed of 20 mm/min until the test piece breaks.
Next, the tensile elongation at break is determined using the following formula.
Tensile elongation at break (%) = [(grabbing interval at break - gripping interval when the initial load is applied to the test piece) / gripping interval when the initial load is applied to the test piece] x 100 (%)

The 50% elongation recovery rate in the MD direction of the nonwoven fabric according to this embodiment is preferably 50% or more, more preferably 55% or more. The 50% elongation recovery rate in the MD direction of the nonwoven fabric according to this embodiment is 100% or less, for example, 90% or less.
Since the 50% elongation recovery rate in the MD direction of the nonwoven fabric according to the present embodiment is 50% or more, the nonwoven fabric according to the present embodiment has excellent stretchability in the MD direction.

The 50% elongation recovery rate in the CD direction of the nonwoven fabric according to this embodiment is preferably 50% or more, more preferably 55% or more. The 50% elongation recovery rate in the CD direction of the nonwoven fabric according to this embodiment is 100% or less, for example, 90% or less.
Since the nonwoven fabric according to the present embodiment has a 50% elongation recovery rate in the CD direction of 50% or more, the nonwoven fabric according to the present embodiment has excellent stretchability in the CD direction.

It is preferable that the 50% elongation recovery rate of the nonwoven fabric in the MD direction is 50% or more, and/or the 50% elongation recovery rate of the nonwoven fabric in the CD direction is 50% or more.
Moreover, it is more preferable that the 50% elongation recovery rate of the nonwoven fabric in the MD direction is 50% or more, and the 50% elongation recovery rate of the nonwoven fabric in the CD direction is 50% or more.

In the measurement of the 50% elongation recovery rate, the 50% elongation recovery rate is measured in accordance with JIS L1096:2010 "Fabric testing method for woven and knitted fabrics".
Specifically, the 50% elongation recovery rate can be determined as follows.
First, a test piece (width: 50 mm, length: 300 mm) is cut out from a nonwoven fabric.
Next, the test piece is attached to a constant speed extension type tensile tester with an initial load and a grip interval of 200 mm. In other words, the gripping interval when the initial load is applied to the test piece is 200 mm. However, for the initial load, the test piece should be pulled by hand to the extent that no slack occurs.
Then, after applying a load to 50% of the grip interval at a pulling speed of 200 mm/min, it is held for 1 minute, and then returned to the original position while unloading at the same speed.
50% elongation recovery rate (%) = [(grabbing interval at 50% elongation - gripping interval at which the load becomes 0 during unloading) / (grabbing interval at 50% elongation - when the initial load is applied to the test piece) Grasp interval)] x 100 (%)

The nonwoven fabric according to this embodiment is preferably a directly spun nonwoven fabric.
The direct-spinning nonwoven fabric means "a nonwoven fabric obtained by directly intertwining raw yarns obtained by melt spinning to form a sheet, and solidifying the raw yarns." Note that "to directly intertwine the yarns to form a sheet" means "to intertwine the yarns to form a sheet before the yarns solidify."
Examples of the directly spun nonwoven fabric include melt blown nonwoven fabric, spunbond nonwoven fabric, flash spun nonwoven fabric, and electrospun nonwoven fabric.
Note that the concept of the melt-blown nonwoven fabric includes a nonwoven fabric obtained by the spun-blown (registered trademark) method.
The nonwoven fabric according to this embodiment is more preferably a meltblown nonwoven fabric or a spunbond nonwoven fabric, and even more preferably a meltblown nonwoven fabric.

The nonwoven fabric according to this embodiment can be suitably used as a base material for various products (e.g., masks, filters, disposable diapers, sanitary napkins, taping materials, patches, wrapping bags, gloves, clothing, etc.). can.
Note that the base material is a concept that includes a reinforcing material.
Examples of the filters include removal filters (e.g., mask filters) that remove particles (e.g., particles with viruses and the like, pollen, etc.), blood filters that collect blood cells, and beverage extraction filters (e.g., coffee drip filters). filters, tea bags, etc.).
The nonwoven fabric according to this embodiment is particularly suitably used as a base material for an ear hook part of a mask or a reinforcing material for a mask.

<Method for manufacturing nonwoven fabric>
Although the nonwoven fabric according to this embodiment is configured as described above, next, a method for manufacturing the nonwoven fabric according to this embodiment will be described.

The method for manufacturing a nonwoven fabric according to the present embodiment uses a nozzle having a nozzle hole to manufacture a nonwoven fabric containing fibers.
The method for manufacturing a nonwoven fabric according to the present embodiment includes a step (A) of obtaining a yarn by discharging a melt from the nozzle hole, and a step (B) of stretching the yarn.
The melt contains a poly(3-hydroxyalkanoate) resin.
The poly(3-hydroxyalkanoate) resin includes a copolymer having 3-hydroxybutyrate units.
The content of the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less.
The ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is 300 or more.

Below, the method for manufacturing a nonwoven fabric according to the present embodiment will be explained using, as an example, a method for obtaining a nonwoven fabric by a melt blown method.
Note that the melt blown method is a concept that also includes the spun blown (registered trademark) method.

The melt is obtained from a raw material composition.
In the step (A), a raw material composition is melted by heating to obtain a melt, and the melt is discharged from the nozzle hole to obtain a yarn.

The melt mass flow rate (MFR) of the raw material composition at 165° C. is preferably 1.0 to 1500 g/10 min, more preferably 2.0 to 1000 g/10 min, even more preferably 5.0 to 1000 g/10 min, especially Preferably it is 10 to 800 g/10 min.

When the melt mass flow rate at 165° C. of the raw material composition is 1500 g/10 min or less, the strength and elongation of the nonwoven fabric are further increased.
By having a melt mass flow rate of 1.0 g/10 min or more at 165° C. of the raw material composition, the tension applied to the yarn during stretching can be lowered, and the fiber diameter of the fibers in the resulting nonwoven fabric can be easily reduced. Become. As a result, the efficiency of particle collection by the nonwoven fabric increases.
Further, since the melt mass flow rate at 165° C. of the raw material composition is 1.0 g/10 min or more, it is possible to suppress the formation of lumps of polymer components when producing a nonwoven fabric. As a result, the productivity of nonwoven fabrics is improved. Moreover, since the melt mass flow rate at 165° C. of the raw material composition is 1.0 g/10 min or more, clogging of the nozzle hole of the nozzle can be suppressed when producing a nonwoven fabric. As a result, the productivity of nonwoven fabrics is improved.

Regarding the melt mass flow rate (MFR) of the raw material composition at 165°C, the melt volume flow rate (MFR) of the raw material composition at 165°C is determined by method B of ASTM-D1238 (ISO1133-1, JIS K7210-1:2011). The melt mass flow rate (MFR) of the raw material composition at 165° C. is determined from the melt volume flow rate (MVR) of the raw material composition at 165° C. and the density of the raw material composition.
Moreover, the melt volume flow rate (MVR) at 165° C. of the raw material composition 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.

The weight average molecular weight of the raw material composition is preferably 100,000 to 550,000, more preferably 110,000 to 500,000, even more preferably 110,000 to 450,000, particularly preferably 200,000 to 450. ,000.

When the weight average molecular weight of the raw material composition is 100,000 or more, the strength and elongation of the nonwoven fabric are increased.
Furthermore, when the weight average molecular weight of the raw material composition is 200,000 or more, the nonwoven fabric becomes even more difficult to tear.
When the weight average molecular weight of the raw material composition is 550,000 or less, the tension applied to the yarn during drawing can be lowered, making it easier to reduce the fiber diameter of the fibers in the resulting nonwoven fabric. As a result, the efficiency of particle collection by the nonwoven fabric increases.
Moreover, since the weight average molecular weight of the raw material composition is 550,000 or less, the generation of lumps of polymer components can be suppressed when producing a nonwoven fabric. As a result, the productivity of nonwoven fabrics is improved. Moreover, since the weight average molecular weight of the raw material composition is 550,000 or less, clogging of the nozzle hole of the nozzle can be suppressed when producing the nonwoven fabric. As a result, the productivity of nonwoven fabrics is improved.

The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70.0 mol% or more and 92.0 mol% or less, preferably 80.0 mol%. The content is 92.0 mol % or more, more preferably 82.0 mol or more and 92.0 mol % or less, even more preferably 85.0 mol or more and 91.6 mol % or less.
When the content of the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the melt is 70.0 mol % or more, the rigidity of the fiber becomes high.
When the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 92.0 mol% or less, the nonwoven fabric according to the present embodiment becomes difficult to tear. . Further, since the content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin is 92.0 mol% or less, the nonwoven fabric according to the present embodiment is less likely to become fluffy.

The content ratio of the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the melt is the same as the content of the 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric. It means the content ratio of the 3-hydroxybutyrate unit.
The content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the melt is determined by using the dried poly(3-hydroxyalkanoate) resin contained in the melt, It can be determined in the same manner as the above-mentioned "content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric."
In addition, the content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition (the "raw material composition" will be described later) is determined by It may also be the content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin.

In the method for manufacturing a nonwoven fabric according to the present embodiment, a nonwoven fabric is obtained from the raw material composition using a nonwoven fabric manufacturing apparatus.

As shown in FIG. 1, the nonwoven fabric manufacturing apparatus 1 includes 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, and a hopper 2 that supplies the raw material composition to the extruder 3. A kneader 6 that obtains a melted material in a kneaded state by kneading, a nozzle 7 that obtains a raw yarn by discharging the melt in the form of fibers, and a nozzle 7 that collects and cools the raw yarn. A collection machine 8 for obtaining a first nonwoven fabric B, and a winding device 9 for winding up the first nonwoven fabric B are provided.

Further, the nonwoven fabric manufacturing apparatus 1 may include a gear pump 4 for supplying the melt from the extruder 3 to the kneader 6, if necessary.
By including the gear pump 4, the nonwoven fabric manufacturing apparatus 1 can suppress fluctuations in the amount of melt supplied to the kneader 6.

Further, the nonwoven fabric manufacturing apparatus 1 may include a filter 5 for removing foreign matter from the melt on the upstream side of the kneader 6, if necessary.

In the 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 melt.

The raw material composition supplied to the extruder 3 is preferably in the form of a solid, more preferably in the form of pellets.
In addition, the raw material composition supplied to the extruder 3 is heated and dried from the viewpoint of suppressing hydrolysis of the resin of the raw material composition and suppressing oxidative deterioration of the resin of the raw material composition. It is preferable that the
The amount of water in the raw material composition supplied to the extruder 3 is preferably 200 ppmw or less.
When drying the raw material composition, it is preferable to remove oxygen in the atmosphere or in the raw material composition. The atmosphere during drying is preferably an atmosphere of inert gas (eg, nitrogen gas, etc.).
In the step (A), the raw material composition may be dried before being supplied to the hopper 2, or the hopper 2 may be a hopper type dryer and the raw material composition may be dried in the hopper 2. Good too.

Examples of the extruder 3 include a single-screw extruder, a co-direction meshing twin-screw extruder, a co-direction non-meshing twin-screw extruder, a different-direction non-meshing twin-screw extruder, and a multi-screw extruder. It will be done.
As the extruder 3, a single-screw extruder is preferable from the viewpoints that thermal deterioration of the raw material composition during extrusion is easily suppressed due to the small resin retention part in the extruder, and from the viewpoint that equipment costs are low. .

Further, in the step (A), the melt is supplied to the kneader 6 via the filter 5 by the gear pump 4, and the melt is kneaded by the kneader 6, thereby obtaining the melt in a kneaded state.

Examples of the filter 5 include a screen mesh, a pleated filter, a leaf disk filter, and the like.
As the filter 5, a leaf disk type filter is preferable from the viewpoints of filtration accuracy, filtration area, and pressure resistance performance, and from the viewpoint of being less likely to be clogged by foreign matter.
As the filter medium of the filter 5, for example, a sintered nonwoven fabric of metal fibers can be used.

In the step (A), the melt is discharged from the nozzle 7 in the form of fibers to obtain raw yarn.

The nozzle 7 is a spinning die head.
In FIG. 2, the nozzle 7 has a plurality of nozzle holes 7a from which raw yarn A is obtained by discharging the melt in the form of fibers. Then, as shown in FIG. 2, the nozzle 7 discharges a plurality of yarns A.
Note that the nozzle 7 may have only one nozzle hole 7a. That is, the nozzle 7 may discharge only one yarn A.

The plurality of nozzle holes 7a are open downward.
The shape of the opening of the nozzle hole 7a is, for example, circular (a concept including circular, substantially circular, elliptical, and substantially elliptical).
The opening diameter of the nozzle hole 7a is appropriately selected depending on the fiber diameter of the fibers of the nonwoven fabric.
The opening diameter of the nozzle hole 7a is preferably 0.05 mm or more, more preferably 0.10 mm or more, and still more preferably 0.12 mm or more.
Further, the opening diameter of the nozzle hole 7a is preferably 1.0 mm or less, more preferably 0.50 mm or less, still more preferably less than 0.30 mm, particularly preferably 0.25 mm or less.
The aperture diameter means the arithmetic mean value of the aperture diameters.

The ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is 300 or more, preferably 300 to 20,000, more preferably 400 to 20,000, still more preferably 500 to 15,000.
By setting the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber to be 300 or more, it is possible to increase the tensile elongation at break in the MD direction of the nonwoven fabric and the tensile elongation at break in the CD direction of the nonwoven fabric. can.
Note that the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber serves as an index of the stretching ratio.

The cross-sectional area of the fiber can be determined from the average fiber diameter of the fiber, assuming that the cross-section of the fiber is circular.

The opening area of the nozzle hole means the average value of the opening area of the nozzle hole. Note that when the opening is circular, the opening area of the nozzle hole can be determined from the arithmetic mean value of the opening diameters.

In the nozzle 7, a plurality of nozzle holes 7a are arranged in a row at intervals.
In FIG. 2, a plurality of nozzle holes 7a are lined up in one row.
Note that the number of rows of the plurality of nozzle holes 7a may be two or more. In other words, the melt blown method may be a spun blown (registered trademark) method.
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 even more preferably 0.25 mm or more.
By setting the distance (interval) between adjacent nozzle holes 7a to 0.05 mm or more, it is possible to suppress the adjoining raw yarns from fusing together, and as a result, the coefficient of variation of the fiber diameter of the fiber can be reduced. can do.
Further, the distance (interval) between adjacent nozzle holes 7a is preferably 1.0 mm or less, more preferably 0.7 mm or less, and even more preferably 0.5 mm or less.
Although the distances between adjacent nozzle holes 7a may or may not be equal, it is preferable that the distances be equal because it facilitates the production of a homogeneous nonwoven fabric.
The distance (interval) between adjacent nozzle holes 7a means the arithmetic average value of the distance (interval) between adjacent nozzle holes 7a.

The collector 8 has a collection surface that collects the yarn A.
The collector 8 is a conveyor.
The conveyor includes a conveyor belt 8a having the collection surface and a plurality of rollers 8b that drive the conveyor belt 8a.
The collection surface is arranged directly below the nozzle hole 7a.
The conveyor belt 8a has air permeability. Specifically, the conveyor belt 8a is made of a mesh material. That is, the collection surface has a mesh shape.
Note that the collector 8 only needs to have a collector, and instead of the conveyor, it may be a collection drum or a collection net.

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 still more preferably 80 mm or more.
Further, the distance (DCD) between the nozzle hole 7a and the conveyor belt 8a serving as the collecting section is preferably 250 mm or less.
The distance (DCD) between the nozzle hole 7a and the collection surface means the arithmetic mean value of the distance (DCD) between the nozzle hole 7a and the collection surface.

The nonwoven fabric manufacturing apparatus 1 is configured to stretch the yarn A by spraying gas C onto the yarn A, as shown in FIG.

In the step (B), gas C is blown onto the yarn A, and the gas C blown onto the yarn A is passed through a mesh conveyor belt 8a.
In the step (B), it is preferable that the gas C blown onto the yarn A be sucked by a suction (not shown) so that the gas C can easily pass through the mesh conveyor belt 8a. This makes it easier to prevent the yarn from bouncing back on the collecting surface of the mesh-like conveyor belt 8a, and as a result, it becomes easier to form the first nonwoven fabric B in which the fibers are well fused together.

The air volume of the gas C blown onto the yarn A is preferably 500 NL/min or more, more preferably 1000 NL/min or more, and still more preferably 2000 NL/min or more.
Moreover, the air volume of the gas C blown onto the yarn A is preferably 12,000 NL/min or less, more preferably 10,000 NL/min or less.

The gas C blown onto the yarn A is a high temperature gas.
The temperature of the gas C blown onto the yarn A is preferably 150°C to 195°C, more preferably 155°C to 190°C, even more preferably 160°C to 185°C.

Examples of the gas C include air and inert gas (nitrogen gas, etc.).
Examples of the method of spraying the high temperature gas C include a method of heating the gas C pressurized by a compressor (not shown) with a heater (not shown).

In step (B), the temperature and air volume of gas C are appropriately controlled in order to obtain a nonwoven fabric with a high degree of crystallinity.

In the step (B), the drawn yarn A is collected by the conveyor belt 8a and cooled while being conveyed by the conveyor belt 8a, thereby obtaining the first nonwoven fabric B.

The material constituting the mesh-like collection surface has heat resistance against the temperature conditions related to the production of the first nonwoven fabric B, does not excessively fuse with the first nonwoven fabric B, and peels off the first nonwoven fabric B. There is no particular limitation as long as the material is possible.

The moving speed at which the first nonwoven fabric B is moved by the conveyor belt 8a (the moving speed of the conveyor belt 8a) is determined by taking into consideration the discharge amount of the raw material composition and the apparent density of the obtained first nonwoven fabric B. It will be decided as appropriate.
The moving speed is preferably within a range of 0.2 m/min or more and 6.0 m/min or less.

In the step (B), the first nonwoven fabric B is transferred to the winding device 9 using the conveyor belt 8a, and the first nonwoven fabric B is wound up into a roll by the winding device 9.

In the method for manufacturing a nonwoven fabric according to the present embodiment, by increasing the air volume of the gas blown onto the yarn, it is possible to increase the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber.
Further, in the method for manufacturing a nonwoven fabric according to the present embodiment, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is increased by lowering the amount of melt per unit time discharged from the nozzle hole. be able to. Note that by lowering the rotational speed of the gear pump, the amount of melt discharged from the nozzle hole per unit time can be lowered.

The method for manufacturing a nonwoven fabric according to the present embodiment may include a step (C) of heating the first nonwoven fabric B obtained in the step (B) to obtain a second nonwoven fabric.

Note that when the method for manufacturing a nonwoven fabric according to the present embodiment includes the step (C), the second nonwoven fabric is the nonwoven fabric. On the other hand, when the method for manufacturing a nonwoven fabric according to the present embodiment does not include the step (C), the first nonwoven fabric becomes the nonwoven fabric.

In the method for manufacturing a nonwoven fabric according to the present embodiment, the nonwoven fabric has excellent elasticity through the step (C).
Further, in the method for manufacturing a nonwoven fabric according to the present embodiment, the 50% elongation recovery rate in the CD direction of the nonwoven fabric and the 50% elongation recovery rate in the MD direction of the nonwoven fabric can be increased by the step (C).
Furthermore, in the method for manufacturing a nonwoven fabric according to the present embodiment, the fibers are partially fused to each other in the step (C), and as a result, the fluffing of the nonwoven fabric can be easily suppressed.

The heating temperature range in step (C) is preferably 80°C to 135°C.
The range of heating time within the preferred heating temperature range in step (C) is preferably 2 to 300 minutes, more preferably 5 to 100 minutes, and even more preferably 10 to 50 minutes.
In the step (C), by heating the first nonwoven fabric for 2 minutes or more within a preferred heating temperature range, a 50% elongation recovery rate in the CD direction of the nonwoven fabric and a 50% elongation recovery rate in the MD direction of the nonwoven fabric are achieved. It can be further improved.
Moreover, in the step (C), the productivity of the second nonwoven fabric is improved by heating the first nonwoven fabric within the preferable heating temperature range for 300 minutes or less.

In the step (C), the first nonwoven fabric may be heated with a gas within the preferable heating temperature range.
Examples of the gas include air and inert gas (nitrogen gas, etc.).
The method of heating the first nonwoven fabric with a gas within the preferable heating temperature range includes heating the first nonwoven fabric in a heating furnace with a gas within the preferable heating temperature range, and/or a preferable method. Examples include heating the first nonwoven fabric by spraying a gas within the heating temperature range onto the first nonwoven fabric.

Furthermore, in the step (C), the first nonwoven fabric may be heated within the preferable heating temperature range by sandwiching the first nonwoven fabric between a pair of heating rolls.

In the step (C), it is preferable to heat the first nonwoven fabric in a non-contact manner within the preferable heating temperature range.
In the step (C), when the first nonwoven fabric is heated while being sandwiched between a pair of heating rolls, there is a concern that the first nonwoven fabric may be welded to the heating rolls.
In the step (C), the first nonwoven fabric is heated within the preferable heating temperature range without contact with the heating roll etc., thereby suppressing welding of the first nonwoven fabric to the heating roll etc. It has the advantage of being able to
Examples of a method of heating the first nonwoven fabric in a non-contact manner within the preferable heating temperature range include a method of heating the first nonwoven fabric with a gas within the preferable heating temperature range.

In the step (C), the first nonwoven fabric may be heated while it is wound into a roll.

Moreover, in the step (C), the first nonwoven fabric may be heated in a sheet form without being wound into a roll. For example, the elongated first nonwoven fabric may be heated continuously while being conveyed.

In the step (C), a second nonwoven fabric is obtained by cooling the heated first nonwoven fabric.
The method for cooling the heated first nonwoven fabric may be a method of naturally cooling the heated first nonwoven fabric at room temperature and normal pressure, or a method of cooling the heated first nonwoven fabric with a gas (for example, a gas at room temperature) The heated first nonwoven fabric may be forcedly cooled by spraying the heated first nonwoven fabric.
The method for manufacturing a nonwoven fabric according to the present embodiment includes a step (D) of pressurizing the first nonwoven fabric B obtained in the step (B) for the purpose of fixing the shape of the nonwoven fabric, making it thin, and shaping the nonwoven fabric. May contain.
In the step (D), the first nonwoven fabric B obtained in the step (B) is subjected to pressure treatment. Pressure methods include, for example, a pair of upper and lower rolls with embossed rolls with engravings on their surfaces, or a combination of one roll with a flat (smooth) surface and the other roll with engravings. It is possible to apply pressure using various rolls, such as an embossing roll consisting of an emboss roll, a thermal calendar roll consisting of a pair of upper and lower flat (smooth) rolls, or an air-through method in which hot air is passed through the thickness of the nonwoven fabric. Among these, pressurization using an embossing roll can be preferably employed from the viewpoint that it is possible to maintain appropriate air permeability while improving mechanical strength.
The pressure treatment temperature in step (D), ie, the surface temperature of the pressure roll, is preferably 20°C to 120°C, more preferably 30°C to 100°C, even more preferably 30°C to 80°C. By setting the pressure treatment temperature within this temperature range, the shape of the nonwoven fabric containing poly(3-hydroxyalkanoate) resin can be maintained, and peeling of the sheet and generation of fuzz can be suppressed. On the other hand, if pressure is applied outside this temperature range, the strength and elongation will decrease due to heat, the fibers will not be able to solidify, and the shape of the nonwoven fabric will not be maintained other than sticking to the roll, and the nonwoven fabric will tend to shrink or tear. There is.
The pressure required for pressurization (pressure between rolls) is not particularly limited, but is preferably 20 to 60 Kg/cm, more preferably 30 to 50 Kg/cm, from the viewpoint of shape retention. When the pressure of the pressurized thermal adhesive roll is 20 kg/cm or more, effects such as fixation of shape and thinning of the film can be sufficiently obtained. By being 60 Kg/cm or less, it becomes difficult to apply excessive stress to the nonwoven fabric, and it becomes easy to suppress breakage of the nonwoven fabric.
In the method for manufacturing a nonwoven fabric of this embodiment, step (A), step (B), step (C), and step (D) may be performed continuously or discontinuously. However, it is preferable to carry out the process continuously because the nonwoven fabric can be manufactured more efficiently.

Note that the present invention is not limited to the above embodiments. Further, the present invention is not limited to the above-described effects. Furthermore, the present invention can be modified in various ways without departing from the gist of the present invention.

For example, in the method for manufacturing a nonwoven fabric according to the above embodiment, a nonwoven fabric is manufactured by a melt-blown method, but in the method for manufacturing a nonwoven fabric according to this embodiment, a nonwoven fabric is manufactured by a spunbonding method, a flash spinning method, or an electrospinning method. may be manufactured.
In the method for manufacturing a nonwoven fabric according to the present embodiment, it is preferable that the nonwoven fabric is manufactured by a melt blown method or a spunbond method.

In the method for manufacturing a nonwoven fabric using a spunbond method (method for manufacturing a spunbond nonwoven fabric), the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is 150 or more, preferably 150 to 15,000, more preferably 160 to 15,000, particularly preferably 165-12,000, most preferably 200-10,000.
By setting the ratio of the opening area of the nozzle holes to the cross-sectional area of the fibers to be 150 or more, it is possible to increase the tensile elongation at break in the MD direction of the nonwoven fabric and the tensile elongation at break in the CD direction of the nonwoven fabric. can.

In the spunbonding method, the raw material composition is melted by heating to obtain the melt, and the raw yarn is obtained by discharging the melt from the nozzle hole.
Next, the yarn is drawn by blowing gas onto the yarn.
The temperature of the gas is preferably 2 to 40°C, more preferably 2 to 30°C, even more preferably 5 to 25°C. When the temperature of the gas is 2° C. or higher, the resin is sufficiently solidified, and fusion between the yarns is easily suppressed. When the temperature of the gas is 40° C. or lower, solidification of the resin progresses slowly, making it easier to prevent the yarn from breaking during air stretching.
In the spunbonding method, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased by increasing the amount of gas blown onto the yarn. Further, by lowering the amount of melt per unit time discharged from the nozzle hole, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased.
In addition, in the spunbonding method, the raw yarn may be stretched using a stretching roll. In that case, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased by increasing the number of rotations of the drawing roll. Further, by lowering the amount of melt per unit time discharged from the nozzle hole, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased.
In step (B) in the method for producing a spunbond nonwoven fabric, the fibers are stretched using, for example, a suction device such as an ejector. When using an ejector, it is possible to adjust the spinning speed by adjusting the pressure of air traction. By increasing the amount of air blown (increasing the air pressure), the spinning speed increases and the fibers are drawn more.
In step (B), before pulling and thinning the raw yarn extruded from the spinning nozzle in step (A), rectified air may be applied to the raw yarn using a device that applies rectified air such as quench air. The rectified wind, also called quench wind, has the function of stabilizing the flow of the raw yarn. Moreover, it is also possible to cool the raw yarn, which is a spun filament, by using a cooled gas. It is preferable that the quench air is emitted through a net or mesh and is uniformly sent to the yarn. The rectified air may be blown from one side or both sides of the yarn intertwined with each other, or may be blown circumferentially. In the method for producing spunbond nonwoven fabric, the temperature of the quench air is preferably 2 to 40°C, more preferably 2 to 30°C, and even more preferably 5 to 25°C. When the temperature of the quench air is 2° C. or higher, the resin is sufficiently solidified, and fusion between the raw yarns is easily suppressed. When the temperature of the quench air is 40° C. or less, solidification of the resin progresses slowly, and it becomes easier to suppress yarn breakage of the raw yarn during air stretching. The wind speed of the quench wind is preferably 0.1 to 3 m/sec. When the wind speed of the quench wind is 0.1 m/sec or more, the effect of rectification is more likely to be exhibited. When the wind speed of the quench wind is 3 m/sec or less, it becomes easier to suppress yarn disturbance.
In the method of producing a nonwoven fabric by the spunbond method, the temperature of gas C blown onto the yarn A (for example, the gas blown onto the yarn when air-pulled by an ejector) is preferably 2° C. to 80° C., more preferably is 5°C to 60°C, more preferably 10°C to 40°C.

In the flash spinning method, the material of the raw material composition and a solvent are mixed under high temperature and high pressure to obtain a molten product under high temperature and high pressure.
Next, by discharging the molten material under high temperature and high pressure from the nozzle hole at room temperature and normal pressure, the yarn is obtained, and the obtained yarn is stretched.
Examples of the solvent include alcohol (eg, methanol, ethanol, etc.), acetone, and the like.
In addition, in the flash spinning method, by increasing the pressure applied to the melt, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased. Further, by lowering the amount of melt per unit time discharged from the nozzle hole, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased.

In the electrospinning method, the raw material composition is heated and melted by irradiating the raw material composition with a laser beam while a high voltage is applied. As a result, the melt can be obtained.
Next, a raw yarn is obtained by discharging the melted material from the nozzle hole.
Then, the yarn is stretched by electrostatic force.
In addition, in the electrospinning method, by increasing the electrostatic force, it is possible to increase the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber. Further, by lowering the amount of melt per unit time discharged from the nozzle hole, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber can be increased.

[Disclosure items]
Each of the following items is a disclosure of a preferred embodiment.

[Item 1]
A nonwoven fabric containing fibers,
The fiber is formed from a resin composition containing a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 70.0 mol% or more and 92.0 mol% or less,
The nonwoven fabric has a tensile elongation at break in the MD direction of 100% or more,
The nonwoven fabric has a tensile elongation at break in the CD direction of 100% or more.

[Item 2]
The nonwoven fabric according to item 1, wherein a 50% elongation recovery rate in the MD direction of the nonwoven fabric is 50% or more, and/or a 50% elongation recovery rate of the nonwoven fabric in the CD direction is 50% or more.

[Item 3]
The nonwoven fabric according to

item

1 or 2, wherein the nonwoven fabric has a basis weight of 20 to 150 g/m ² .

[Item 4]
The nonwoven fabric according to any one of items 1 to 3, wherein the nonwoven fabric is a directly spun nonwoven fabric.

[Item 5]
The poly(3-hydroxyalkanoate) resin is a poly(3-hydroxyalkanoate) resin component in which the content of 3-hydroxybutyrate units is 76 mol% or less. The nonwoven fabric according to any one of items 1 to 4, comprising:

[Item 6]
A method for producing a nonwoven fabric, the method comprising producing a nonwoven fabric containing fibers using a nozzle having a nozzle hole,
a step (A) of obtaining a raw yarn by discharging the melt from the nozzle hole;
and a step (B) of stretching the yarn,
The raw material composition contains a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less,
A method for producing a meltblown nonwoven fabric, wherein the ratio of the opening area of the nozzle holes to the cross-sectional area of the fibers is 300 or more.

[Item 7]
The method for producing a meltblown nonwoven fabric according to item 6, wherein in the step (B), the raw yarn is stretched by blowing gas at 150° C. to 195° C. onto the raw yarn.

[Item 8]
A method for producing a nonwoven fabric, the method comprising producing a nonwoven fabric containing fibers using a nozzle having a nozzle hole,
a step (A) of obtaining a raw yarn by discharging the melt from the nozzle hole;
and a step (B) of stretching the yarn,
The raw material composition contains a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less,
A method for producing a spunbond nonwoven fabric, wherein the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is 150 or more.

[Item 9]
The method for producing a spunbond nonwoven fabric according to item 8, wherein in the step (B), the yarn is stretched by blowing gas at 2° C. to 40° C. onto the yarn.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Note that the present invention is not limited to these Examples at all.

The following materials were prepared.

(Poly(3-hydroxyalkanoate) resin (P3HA))
The following P3HA-1 was produced according to the method described in Example 1 of International Publication No. 2019/142845.
P3HA-1: P3HB3HH (3-hydroxybutyrate unit content: 94.5 mol%, 3-hydroxyhexanoate (3HH) unit content: 5.5 mol%)
The following P3HA-2 was produced according to the method described in Example 6 of International Publication No. 2021/206155.
P3HA-2: P3HB3HH (content ratio of 3-hydroxybutyrate units: 85.0 mol%, content ratio of 3-hydroxyhexanoate (3HH) units: 15.0 mol%) (weight ratio of MIBK soluble fraction : 54% by weight, content of 3-hydroxybutyrate units in MIBK soluble fraction: 74.0 mol%, content of 3-hydroxyhexanoate (3HH) units in MIBK soluble fraction: 26.0 mol% ) (Weight percentage of MIBK-insoluble fraction: 46% by weight, Content percentage of 3-hydroxybutyrate units in MIBK-insoluble fraction: 98.0 mol%, 3-hydroxyhexanoate (3HH) units in MIBK-insoluble fraction content ratio: 2.0 mol%)
In addition, if necessary, P3HA-1 and P3HA-2 are heat-treated at high temperature and humidity (temperature: 120°C, humidity: 100%) using a highly accelerated life test device (manufactured by ESPEC, EHS-222MD). By this, the weight average molecular weight (Mw) and melt mass flow rate (MFR) at 165° C. of P3HA-1 and P3HA-2 were adjusted.
That is, by increasing the heat treatment time, the weight average molecular weight (Mw) was lowered and the melt mass flow rate (MFR) at 165°C was increased.

The content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in P3HA-1 were determined as follows.
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, and the sample was sealed. By heating the sample at 100° C. for 140 minutes, a first reaction solution containing methyl ester, which is a decomposition product of P3HA-1, was obtained.
Then, the first reaction liquid is cooled, 1.5 g of sodium hydrogen carbonate is added little by little to the cooled first reaction liquid to neutralize it, and the second reaction liquid is left to stand until the generation of carbon dioxide gas stops. A reaction solution was obtained.
Furthermore, a mixture was obtained by thoroughly mixing the second reaction solution and 4 mL of diisopropyl ether.
Next, the mixture was centrifuged to obtain a supernatant.
Then, by analyzing the monomer unit composition of the decomposed product in the supernatant liquid by capillary gas chromatography under the following conditions, the content of 3-hydroxybutyrate units in P3HA-1 and 3-hydroxyhexanoate (3HH ) unit content was determined.
Gas chromatograph: GC-17A manufactured by Shimadzu Corporation
Capillary column: NEUTRA BOND-1 manufactured by GL Science (column length: 25 m, column inner diameter: 0.25 mm, liquid film thickness: 0.4 μm)
Carrier gas: He
Column inlet pressure: 100kPa
Sample amount: 1μL
Regarding the temperature conditions, the temperature was raised at a rate of 8°C/min from 100 to 200°C, and further at a rate of 30°C/min from 200 to 290°C.

In addition, the content ratio of 3-hydroxybutyrate units and the content ratio of 3-hydroxyhexanoate (3HH) units in P3HA-2 are also the same as the content ratio of 3-hydroxybutyrate units in P3HA-1 and the content ratio of 3-hydroxyhexanoate (3HH) units. It was determined in the same manner as the content of ate (3HH) units.
Furthermore, P3HA-2 was fractionated into an MIBK-soluble fraction and an MIBK-insoluble fraction using the MIBK fractionation method described above. The content of 3-hydroxybutyrate units and the content of 3-hydroxyhexanoate (3HH) units in the MIBK-soluble fraction and MIBK-insoluble fraction were also determined by the 3-hydroxybutyrate units in P3HA-1. It was determined in the same manner as the content ratio of rate units and the content ratio of 3-hydroxyhexanoate (3HH) units.

(Lubricant)
BA: Behenic acid amide (also referred to as "behenic acid amide") (manufactured by Nippon Fine Chemical Co., Ltd., BNT-22H)
EA: Erucic acid amide (manufactured by Nippon Fine Chemical Co., Ltd., Neutron S)

(crystal nucleating agent)
PETL: Pentaerythritol (manufactured by Taisei Kayaku Co., Ltd., Neurizer P)

(Examples 1 to 9 and Comparative Examples 1 and 2)
A raw material composition was obtained by melting and kneading the above materials at the mixing ratios shown in Table 1 below.

(Content ratio of each monomer unit in the entire poly(3-hydroxyalkanoate) resin)
The content of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition is the content of 3-hydroxybutyrate units in P3HA-1 and 3-hydroxybutyrate units in P3HA-2. It was calculated from the content ratio of butyrate units and the blending ratio of P3HA-1 and P3HA-2.
Furthermore, the content ratio of 3-hydroxyhexanoate (3HH) units in the entire poly(3-hydroxyalkanoate)-based resin contained in the raw material composition was calculated in the same manner.
Note that "the content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition" refers to the "content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric". It also means "the content ratio of 3-hydroxybutyrate units in the entire poly(3-hydroxyalkanoate) resin contained in the melt".
In addition, the "content ratio of 3-hydroxyhexanoate (3HH) units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition" is the "content ratio of 3-hydroxyhexanoate (3HH) units in the entire poly(3-hydroxyalkanoate) resin contained in the raw material composition". 3-hydroxyhexanoate (3HH) unit content in the entire poly(3-hydroxyalkanoate) resin contained in the melt. ) also means the content ratio of units.
The calculated values are shown in Table 1 below.

(Measurement of physical properties in raw material composition)
The weight average molecular weight (Mw) and melt mass flow rate (MFR) at 165°C were measured for the raw material composition.
Each measured value is shown in Table 1 below.
Note that the weight average molecular weight (Mw) of the raw material composition was calculated by GPC measurement. The conditions for GPC measurement are shown below.
Measuring device: Shimadzu 20A manufactured by Shimadzu Corporation
Column: ShodexK-806M manufactured by Showa Denko
Detector: RI detector Standard material: Polystyrene Eluent: Chloroform (HPLC grade)
Flow rate: 1mL/min
Temperature: 40℃

Using the nonwoven fabric manufacturing apparatus shown in FIGS. 1 to 3, a first nonwoven fabric was manufactured from the raw material composition by the melt blowing method under the conditions shown in Table 2 below. Note that a nozzle with a width of 600 mm was used to manufacture the nonwoven fabric.

Next, the first nonwoven fabric was heated using a box-type hot air dryer (manufactured by ESPEC, PH-202) under the heating conditions shown in Table 2 below, and then at room temperature and pressure (20°C, 1 atm). By natural cooling, the second nonwoven fabrics of Examples 1 to 9 and Comparative Examples 1 to 2 were obtained.

(Example 10)
The first nonwoven fabric of Example 4 was made into the nonwoven fabric of Example 10.

(Examples 11, 12, 15, 16 and Comparative Examples 3 and 4)
The spunbond method was used instead of the melt-blown method, the materials were melt-kneaded in the proportions shown in Table 1 below, and the first nonwoven fabric was manufactured from the raw material composition under the conditions shown in Table 2 below. The raw yarn discharged from the spinning nozzle was blown with rectified wind (quench wind) at 12.5°C from both sides of the entangled yarn at a wind speed of 0.5 m/sec, using an ejector. A nonwoven fabric was obtained in the same manner as in Example 10, except that the yarn was air-pulled by blowing air at 25° C. onto the yarn, and the nonwoven fabric was manufactured under the conditions shown in Table 2 below.

(Examples 13 and 14)
The first nonwoven fabric was manufactured from the raw material composition under the conditions shown in Table 2 below, and the first nonwoven fabric was pressure-treated (embossed) using an embossing roll set at the temperature shown in Table 2 below. A nonwoven fabric was obtained in the same manner as in Example 11 except for the above.

(Measurement of various physical properties in nonwoven fabric)
Regarding the nonwoven fabric, the basis weight, thickness, average fiber diameter of the fibers, coefficient of variation of the fiber diameter of the fibers, and weight average molecular weight (Mw) of the resin composition were measured.
Each measured value is shown in Table 3 below.
Note that the average value of the fiber diameter of the fibers and the coefficient of variation of the fiber diameter of the fibers were determined using a tabletop scanning electron microscope JCM-6000 manufactured by JEOL.
Moreover, the weight average molecular weight (Mw) of the resin composition was measured in the same manner as the weight average molecular weight (Mw) of the raw material composition.

(Maximum load in CD direction and MD direction of nonwoven fabric, tensile elongation at maximum load point, and tensile elongation at break)
For the nonwoven fabric, the maximum load in the CD direction and MD direction, the tensile elongation at the maximum load point, and the tensile elongation at the break point were measured.
The maximum load in the CD direction and MD direction, the tensile elongation at the maximum load point, and the tensile elongation at the break point are determined according to JIS B7721:2018 "Tensile testing machine/compression testing machine - Calibration method and verification method of force measurement system" It was measured using a constant-speed extension type tensile tester based on .
As a constant speed extension type tensile tester, a universal testing machine (RTG-1210 manufactured by A&D Co., Ltd.) or the like was used.
First, a test piece (width: 8 mm, length: 40 mm) was cut out from the nonwoven fabric.
Next, the test piece was attached to a tensile testing machine with an initial load at a grip interval of 20 mm. In other words, the gripping interval when the initial load was applied to the test piece was 20 mm. However, during the initial load, the test piece was pulled by hand to an extent that no sagging occurred.
Then, a load was applied at a tensile speed of 20 mm/min until the test piece broke, and the maximum loads in the CD direction and MD direction were measured.
Further, the maximum load point tensile elongation and the break point tensile elongation in the CD direction and MD direction were determined using the following formulas.
Maximum load point tensile elongation (%) = [(grabbing 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) x 100 (%)
Tensile elongation at break (%) = [(grabbing interval at break - gripping interval when the initial load is applied to the test piece) / gripping interval when the initial load is applied to the test piece] x 100 (%)
The measured values are shown in Table 3 below.

(Tensile elongation at break in CD direction/Tensile elongation at break in MD direction)
The tensile elongation at break in the CD direction/the tensile elongation at break in the MD direction (CD elongation/MD elongation) was calculated.
The CD elongation/MD elongation is shown in Table 3 below.

(50% elongation recovery rate)
The 50% elongation recovery rate of the nonwoven fabric was measured by the method described above.
The measured values are shown in Table 3 below.
In addition, regarding Comparative Example 1, the nonwoven fabric broke during the measurement of the 50% elongation recovery rate, and the 50% elongation recovery rate could not be measured.

(Opening area of nozzle hole/cross-sectional area of fiber)
The opening area of the nozzle hole/the cross-sectional area of the fiber was calculated by the method described above.
The calculated values are shown in Table 3 below.

(Resistance to tearing of non-woven fabric, elasticity of non-woven fabric, and less fluff of non-woven fabric)
By cutting the nonwoven fabric, two first test pieces were obtained as shown in FIG. 4.
Next, a mask having the shape shown in FIG. 5 was produced by welding the first test pieces together.
Next, a professional engineer wore the mask for 3 hours and evaluated it according to the following criteria.
The results are shown in Table 4 below.

<Tear resistance>
3: No cracks occurred in the mask, and no tears occurred in the welded portions of the mask.
2: A crack of less than 1 cm has occurred in the mask, or a tear of less than 1 cm has occurred in the welded part of the mask (no crack of 1 cm or more has occurred in the mask, and a tear of 1 cm or more has occurred in the welded part of the mask) did not occur).
1: A crack of 1 cm or more occurred in the mask, or a tear of 1 cm or more occurred in the welded part of the mask.

<Stretchability (adhesion)>
3: There was almost no change in the adhesion of the mask, and the mask did not shift from the face.
2: The adhesion of the mask was slightly reduced and the mask sometimes slipped from the face, but there were no problems in use.
1: The adhesion of the mask was greatly reduced, and the mask was torn, making it difficult to wear.

<Low fluff>
3: Visually, no fluff was observed on the mask.
2: Small fuzz was observed on the mask, but the expert technician did not feel itching due to the fuzz.
1: Severe fuzz occurred on the mask, and the expert technician felt itching due to the fuzz.

As shown in Tables 1, 3, and 4, in Examples 1, 3, 4, 6 to 8, and 10 to 16, which are within the scope of the present invention, in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric, Comparative Example 1 in which the content of 3-hydroxybutyrate units is 94.5% and the tensile elongation at break in the MD direction of the nonwoven fabric is 49%, and the tensile elongation at break in the CD direction of the nonwoven fabric is 95%. % and the tensile elongation at break in the MD direction of the nonwoven fabric is 93%, Comparative Example 3 in which the tensile elongation at break in the CD direction of the nonwoven fabric is 83%, and the nonwoven fabric contains The content ratio of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin is 94.7%, the tensile elongation at break in the CD direction of the nonwoven fabric is 66%, and the MD direction of the nonwoven fabric is 66%. The nonwoven fabric was less likely to tear than Comparative Example 4, which had a tensile elongation at break of 72%.

In addition, as shown in Tables 1, 3, and 4, in Examples 1, 3, 4, 6 to 8, and 10, which are within the scope of the present invention, in the manufacturing method of melt blown nonwoven fabric, poly(3 Comparative Example 1 in which the content of 3-hydroxybutyrate units in the -hydroxyalkanoate)-based resin was 94.5%, and Comparative Example 2 in which the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber was 238. In comparison, non-woven fabric was less likely to tear.
Further, as shown in Tables 1, 3, and 4, in Examples 11 to 16, which are within the scope of the present invention, in the method for producing spunbond nonwoven fabric, the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber was 113. Compared to Comparative Example 3 and Comparative Example 4 in which the content of 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin contained in the melt was 94.7%, the nonwoven fabric was less likely to tear. Ta.

As shown in Table 3, in Examples 1 to 10, which are within the scope of the present invention, the tensile elongation at break in the CD direction and the tensile elongation at break in the MD direction were higher than in Comparative Examples 1 and 2. .
Therefore, in Examples 2, 5, and 9 as well as in Examples 1, 3, 4, 6 to 8, and 10, it is presumed that the nonwoven fabrics are less likely to tear than in Comparative Examples 1 and 2.

Therefore, it can be seen that according to the present invention, a tear-resistant nonwoven fabric can be provided.

Furthermore, as shown in Tables 3 and 4, in Examples 1, 3, 4, and 10 in which the weight average molecular weight (Mw) of the resin composition is 150,000 or more, the weight average molecular weight (Mw) of the resin composition is Compared to Examples 6 and 7, which had a molecular weight of 147,000 or less, the nonwoven fabric was less likely to tear.
Therefore, it can be seen that when the weight average molecular weight (Mw) of the resin composition is 150,000 or more, the nonwoven fabric becomes difficult to tear.

Furthermore, as shown in Tables 1 and 4, in Examples 1, 3, 4, and 10 in which the weight average molecular weight (Mw) of the raw material composition is 200,000 or more, the weight average molecular weight (Mw) of the raw material composition is The nonwoven fabric was less likely to tear than Examples 6 and 7, which had a molecular weight of 198,000 or less.
Therefore, it can be seen that when the weight average molecular weight (Mw) of the raw material composition is 200,000 or more, the nonwoven fabric becomes difficult to tear.

Furthermore, as shown in Table 4, in Examples 1, 3, 4, and 10, the nonwoven fabrics were less likely to tear than in Example 8.

Furthermore, as shown in Table 4, in Examples 1, 3, 4, 6 to 8, and 10 to 16, which are within the scope of the present invention, the nonwoven fabrics had excellent elasticity compared to Comparative Examples 1 to 4. .

Furthermore, as shown in Table 4, in Example 4, in which a second nonwoven fabric was obtained by heating the first nonwoven fabric of Example 10, the nonwoven fabric had superior elasticity compared to Example 10. Ta.
Therefore, it can be seen that by heating the nonwoven fabric, the nonwoven fabric has excellent elasticity.

In addition, as shown in Table 3, in Example 4 in which a second nonwoven fabric was obtained by heating the first nonwoven fabric of Example 10, the 50% elongation recovery rate in the CD direction of the nonwoven fabric and the MD of the nonwoven fabric The 50% elongation recovery rate in the direction was high.
Therefore, it can be seen that heating the nonwoven fabric increases the 50% elongation recovery rate of the nonwoven fabric in the CD direction and the 50% elongation recovery rate of the nonwoven fabric in the MD direction.

Furthermore, as shown in Table 4, in Examples 1, 3, 4, 6 to 8, and 10 to 16, which are within the scope of the present invention, the fluff of the nonwoven fabrics was less than in Comparative Examples 1 and 4.

Furthermore, as shown in Table 4, in Examples 13 and 14 in which the first nonwoven fabric was pressure-treated, the nonwoven fabric had less fluff.

1: Nonwoven fabric manufacturing equipment, 2: hopper, 3: extruder, 4: gear pump, 5: filter, 6: kneader, 7: nozzle, 7a: nozzle hole, 8: collector, 8a: conveyor belt, 8b : Roller, 9: Winding device,
A: Yarn, B: First nonwoven fabric, C: Gas

Claims

A nonwoven fabric containing fibers,
The fiber is formed from a resin composition containing a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content ratio of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the nonwoven fabric is 70.0 mol% or more and 92.0 mol% or less,
The nonwoven fabric has a tensile elongation at break in the MD direction of 100% or more,
The nonwoven fabric has a tensile elongation at break in the CD direction of 100% or more.
The nonwoven fabric according to claim 1, wherein a 50% elongation recovery rate in the MD direction of the nonwoven fabric is 50% or more, and/or a 50% elongation recovery rate of the nonwoven fabric in the CD direction is 50% or more.
The nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric has a basis weight of 20 to 150 g/m 2 .
The nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric is a directly spun nonwoven fabric.
The poly(3-hydroxyalkanoate)-based resin includes a poly(3-hydroxyalkanoate)-based resin component having a content of 3-hydroxybutyrate units of 76 mol% or less, according to claim 1 or 2. non-woven fabric.
A method for producing a nonwoven fabric, the method comprising producing a nonwoven fabric containing fibers using a nozzle having a nozzle hole,
a step (A) of obtaining a raw yarn by discharging the melt from the nozzle hole;
and a step (B) of stretching the yarn,
The raw material composition contains a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less,
A method for producing a meltblown nonwoven fabric, wherein the ratio of the opening area of the nozzle holes to the cross-sectional area of the fibers is 300 or more.
The method for producing a meltblown nonwoven fabric according to claim 6, wherein in the step (B), the yarn is stretched by blowing gas at 150° C. to 195° C. to the yarn.
A method for producing a nonwoven fabric, the method comprising producing a nonwoven fabric containing fibers using a nozzle having a nozzle hole,
a step (A) of obtaining a raw yarn by discharging the melt from the nozzle hole;
a step (B) of stretching the yarn,
The raw material composition contains a poly(3-hydroxyalkanoate) resin,
The poly(3-hydroxyalkanoate)-based resin includes a copolymer having 3-hydroxybutyrate units,
The content of the 3-hydroxybutyrate unit in the poly(3-hydroxyalkanoate) resin contained in the melt is 70 mol% or more and 92 mol% or less,
A method for producing a spunbond nonwoven fabric, wherein the ratio of the opening area of the nozzle hole to the cross-sectional area of the fiber is 150 or more.
The method for producing a spunbond nonwoven fabric according to claim 8, wherein in the step (B), the yarn is stretched by blowing gas at 2° C. to 40° C. onto the yarn.