JP2022156696A - Spun-bonded nonwoven fabric and production method of spun-bonded nonwoven fabric - Google Patents

Abstract

To provide a novel spun-bonded nonwoven fabric comprising a fiber having a constituent of copolymer mainly composed of a constitutional unit derived from 4-methyl-1-pentene.SOLUTION: A spun-bonded nonwoven fabric comprises a fiber having a constituent of copolymer A containing 50 mol% or more of a constitutional unit derived from 4-methyl-1-pentene and 1 mol% or more of a constitutional unit derived from α-olefin having 2 to 4 carbon atoms.SELECTED DRAWING: None

Description

The present disclosure relates to spunbond nonwovens and methods of making spunbond nonwovens.

BACKGROUND ART In recent years, nonwoven fabrics made of fibers containing thermoplastic resins such as polypropylene and polyamide have been widely used for various purposes because of their excellent air permeability, flexibility, lightness and the like. As methods for producing nonwoven fabrics, the meltblowing method and the spunbond method, which are suitable for mass production, are widely used.

Polypropylene, polyamide, and the like are mainly used as thermoplastic resins used in the production of nonwoven fabrics, but polyolefins other than polypropylene are sometimes used.

For example, Patent Document 1 describes a meltblown nonwoven fabric in which a copolymer of 4-methyl-1-pentene and propylene is used as a polyolefin, and this copolymer is preferred in terms of heat resistance and lightness. It is

JP 2013-147771 A

The present inventors attempted to produce a spunbond nonwoven fabric using a copolymer of 4-methyl-1-pentene and propylene as described in Patent Document 1, but failed to produce a spunbond nonwoven fabric. It has been difficult to produce a spunbond nonwoven fabric under the general conditions of the process.

The present disclosure has been made in view of the above, and provides a novel spunbond nonwoven fabric containing fibers composed of a copolymer mainly containing structural units derived from 4-methyl-1-pentene and a method for producing the same. intended to provide

Means for solving the above problems include the following embodiments.
<1> Copolymer A containing 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% or more of structural units derived from an α-olefin having 2 to 4 carbon atoms A spunbond nonwoven fabric comprising fibers comprising
<2> The spunbond nonwoven fabric according to <1>, wherein the fiber is a core-sheath type composite fiber having a core portion and a sheath portion.
<3> The spunbond nonwoven fabric according to <2>, wherein the core portion contains the copolymer A.
<4> The spunbond nonwoven fabric according to <2> or <3>, wherein the sheath contains an α-olefin polymer (excluding the copolymer A).
<5> The α-olefin polymer (excluding the copolymer A) contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and has 8 or more carbon atoms. The content of structural units derived from is 10 mol% or less based on all structural units, and the content of structural units derived from α-olefins having 2 to 4 carbon atoms is less than 1 mol% based on all structural units. and the spunbond nonwoven fabric according to <4>, which is at least one selected from the group consisting of a polymer B and a propylene-based polymer.
<6> The spunbond nonwoven fabric according to any one of <2> to <5>, wherein the volume ratio of the sheath to the core is 30:70 to 90:10.
<7> The spunbond nonwoven fabric according to <1>, wherein the fibers are monocomponent fibers.
<8> The spunbond nonwoven fabric according to any one of <1> to <7>, wherein the fibers have an average fiber diameter of 10 μm to 50 μm.
<9> A method for producing a spunbond nonwoven fabric, wherein a thermoplastic resin or a thermoplastic resin composition containing the thermoplastic resin is discharged from a spinning nozzle and melt-spun,
The thermoplastic resin contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% or more of structural units derived from an α-olefin having 2 to 4 carbon atoms. including a polymer A,
A method for producing a spunbond nonwoven fabric, wherein the draft ratio, which is the ratio of the fastest yarn speed to the yarn speed during ejection, is less than 2,000.

INDUSTRIAL APPLICABILITY According to the present disclosure, it is possible to provide a novel spunbond nonwoven fabric containing fibers whose constituent component is a copolymer mainly containing constitutional units derived from 4-methyl-1-pentene, and a method for producing the same.

1 is a schematic diagram of a nonwoven fabric manufacturing apparatus used in a spunbond nonwoven fabric manufacturing method 1. FIG. 1 is a schematic diagram of a nonwoven fabric manufacturing apparatus used in a spunbond nonwoven fabric manufacturing method 2. FIG.

In the present disclosure, a numerical range indicated using "to" indicates a range including the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described stepwise. Moreover, in the numerical ranges described in this specification, the upper limit or lower limit described in a certain numerical range may be replaced with the values shown in the examples.
In the present disclosure, when there are multiple substances corresponding to each component in the composition, the amount of each component in the composition is the total amount of the multiple substances present in the composition unless otherwise specified. means.
In the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.

<Spunbond nonwoven fabric>
The spunbond nonwoven fabric of the present disclosure contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% or more of structural units derived from an α-olefin having 2 to 4 carbon atoms. It contains a fiber having a copolymer A containing as a constituent component.

When attempting to produce a spunbond nonwoven fabric using a copolymer mainly containing structural units derived from 4-methyl-1-pentene, a spunbond nonwoven fabric is produced under general conditions for producing a spunbond nonwoven fabric. It is difficult to manufacture. For example, when the above-mentioned copolymer or a resin composition containing a copolymer is discharged from a spinning nozzle, melt spinning cannot be performed well, and it is difficult to obtain a spunbond nonwoven fabric.

On the other hand, in the present disclosure, by adjusting the conditions for melt-spinning the above-described copolymer or a resin composition containing the copolymer discharged from the spinning nozzle, fibers having the above-described copolymer as a constituent component It is possible to obtain a novel spunbond nonwoven fabric containing.

Applications to which the spunbond nonwoven fabric of the present disclosure is applied are not particularly limited. ); sanitary materials (poultices, sheets, towels, industrial masks, sanitary masks, hair caps, gauze, disposable underwear, supporters, poultices, patches, etc.); , food packaging materials, etc.).

The fibers contained in the spunbond nonwoven fabric of the present disclosure contain 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% of structural units derived from an α-olefin having 2 to 4 carbon atoms. It is not particularly limited as long as the copolymer A containing the above is used as a constituent component.

The form of the fibers contained in the spunbond nonwoven fabric of the present disclosure is not particularly limited, and may be conjugate fibers or monocomponent fibers.

The conjugate fiber preferably contains two or more thermoplastic resins as constituents, for example, two or more copolymers A as constituents, or one or more copolymers A and one It is preferable to use a thermoplastic resin other than the above copolymer A as a constituent component.

Examples of conjugated fibers include core-sheath type, side-by-side type, and sea-island type conjugated fibers, among which core-sheath type conjugated fibers are preferred. The core-sheath type conjugate fiber may be provided with a core portion and a sheath portion, and may be either a concentric core-sheath type or an eccentric core-sheath type. The core of the eccentric core-sheath type conjugate fiber may or may not be exposed on the surface.

When the fibers contained in the spunbond nonwoven fabric of the present disclosure are core-sheath type conjugate fibers, the copolymer A may be contained in at least one of the core and the sheath. Furthermore, it is preferable that one of the core and the sheath contains the copolymer A, and the other of the core and the sheath contains a thermoplastic resin other than the copolymer A. Examples of thermoplastic resins other than copolymer A include α-olefin polymers described later (excluding copolymer A) and other thermoplastic resins.

When the fibers contained in the spunbond nonwoven fabric of the present disclosure are core-sheath type conjugate fibers, the core may contain the copolymer A, and the sheath may contain a thermoplastic resin other than the copolymer A, preferably α - It may contain an olefin polymer (except copolymer A). From the viewpoint of suppressing blocking of the spunbond nonwoven fabric, it is preferable that the core contains the copolymer A, and the sheath contains a thermoplastic resin other than the copolymer A, the core contains the copolymer A, In addition, the sheath preferably contains an α-olefin polymer (excluding copolymer A). Furthermore, from the viewpoint of more preferably suppressing blocking of the spunbond nonwoven fabric by not exposing the core containing the copolymer A from the surface, the core-sheath type conjugate fiber is a concentric core-sheath type, or the core is on the surface. More preferably, it is an eccentric core-sheath type that is not exposed.

When the core contains the copolymer A, the content of the copolymer A may be 80% by mass to 100% by mass, or 90% by mass to 100% by mass, relative to the total amount of the core. may If the sheath contains a thermoplastic resin other than copolymer A or an α-olefin polymer (excluding copolymer A), the content of the thermoplastic resin other than copolymer A or the α-olefin polymer The content of the coalescence (excluding copolymer A) may be 80% by mass to 100% by mass, or 90% by mass to 100% by mass, relative to the total amount of the sheath independently. good too.

The core:sheath volume ratio of the core to the sheath in the core-sheath type composite fiber is preferably 30:70 to 90:10, and from the viewpoint of further improving the stress relaxation property, it is 60:40. ~85:15 is more preferred. When the core contains the copolymer A, the ratio of the core to the sheath is 30 or more (the ratio of the core to the sheath is 30:70 or more), so that the spunbond nonwoven fabric tends to have excellent stress relaxation. When the ratio of the core part to the sheath part is 90:10 or less, the average fiber diameter of the core-sheath type composite fiber tends to be reduced and the blocking resistance tends to be further improved. When the core contains the copolymer A, the core:sheath ratio is preferably 30:70 to 65:35 from the viewpoint of further improving blocking resistance.

A monocomponent fiber is a fiber whose constituent component is a single thermoplastic resin. When the fibers contained in the spunbond nonwoven fabric of the present disclosure are monocomponent fibers, the monocomponent fibers are fibers in which only the copolymer A is a constituent of the resin component, and the monocomponent fibers are a type of copolymer A It is preferable that the fiber is composed of only the resin component.
In the present disclosure, fibers other than composite fibers such as core-sheath, side-by-side, and islands-in-the-sea types may be used as monocomponent fibers.

(Copolymer A)
Copolymer A is a constituent component of the fibers contained in the spunbond nonwoven fabric, and contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and an α-olefin having 2 to 4 carbon atoms. 1 mol % or more of the structural unit that

Examples of α-olefins having 2 to 4 carbon atoms include ethylene, propylene, 1-butene, etc. Among them, propylene is preferred. Copolymer A may contain a structural unit derived from one type of α-olefin having 2 to 4 carbon atoms, and structural units derived from two or more types of α-olefin having 2 to 4 carbon atoms. may contain

The content of structural units derived from 4-methyl-1-pentene contained in copolymer A is 50 mol% or more, relative to all structural units, and from the viewpoint of shape stability, it is 60 mol% or more. It is preferably 70 mol % or more, more preferably 70 mol % or more. The content of structural units derived from 4-methyl-1-pentene is 99 mol% or less, and preferably 90 mol% or less from the viewpoint of further improving stress relaxation properties, based on all structural units. , 80 mol % or less.

The content of structural units derived from α-olefins having 2 to 4 carbon atoms contained in the copolymer A is 1 mol% or more with respect to all structural units, and from the viewpoint of further improving stress relaxation properties. , preferably 10 mol % or more, more preferably 20 mol % or more. The content of structural units derived from α-olefins having 2 to 4 carbon atoms is 50 mol% or less, and preferably 40 mol% or less from the viewpoint of shape stability, relative to all structural units. , 30 mol % or less.

Copolymer A may contain a structural unit derived from a polymerizable compound other than 4-methyl-1-pentene and an α-olefin having 2 to 4 carbon atoms (hereinafter, "other structural unit A"). good. The content of other structural units A that can be contained in the copolymer A is preferably 10 mol% or less, more preferably 5 mol% or less, based on the total structural units, from the viewpoint of shape stability and stress relaxation. .

The melt flow rate (MFR) of copolymer A is not particularly limited as long as it can be melt-spun, and may be 5 g/10 minutes to 30 g/10 minutes, or 7 g/10 minutes to 20 g/10 minutes. good too.
In the present disclosure, MFR is a value measured at a temperature of 230° C. and a load of 2.16 kg according to ASTM D1238.

The density of the copolymer A is not particularly limited as long as it can be melt-spun, and may be 0.820 g/cm ³ to 0.870 g/cm, or 0.830 g/cm ³ to 0.860 g/cm ³ . There may be.
The density of copolymer A can be measured by the method described in Examples below.

The melting point of the copolymer A is not particularly limited as long as it can be melt-spun, and may be lower than 200°C, and the copolymer A does not have to show a melting point.
The melting point of copolymer A can be measured by the method described in Examples below.

Copolymer A is a conventionally known catalyst, for example, vanadium-based catalyst, titanium-based catalyst, magnesium-supported titanium catalyst, International Publication No. 01/53369 pamphlet, International Publication No. 01/27124 pamphlet, JP-A-3-193796. 4-methyl-1-pentene, an α-olefin having 2 to 4 carbon atoms, and, if necessary, other polymerizable It can be obtained by polymerizing a compound.

(Thermoplastic resin other than copolymer A)
Examples of thermoplastic resins other than copolymer A include α-olefin polymers (excluding copolymer A) and other thermoplastic resins.

<<α-olefin polymer (excluding copolymer A)>>
As the α-olefin polymer (excluding copolymer A), for example, α containing 50 mol% or more of structural units derived from 4-methyl-1-pentene and not satisfying the conditions for copolymer A -olefin polymers, α-olefin polymers containing less than 50 mol% of structural units derived from 4-methyl-1-pentene, and the like.

Examples of α-olefin polymers that contain 50 mol% or more of structural units derived from 4-methyl-1-pentene and do not satisfy the conditions for copolymer A include the following polymers (1) and (2): coalescence is mentioned.
(1) 4-methyl-1-pentene homopolymer (2) α-olefin having a content of structural units derived from 4-methyl-1-pentene of 50 mol% or more and having 2 to 4 carbon atoms A copolymer in which the content of structural units derived from is less than 1 mol%

The polymer satisfying the above (1) or (2) contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and contains structural units derived from an α-olefin having 8 or more carbon atoms. is 10 mol% or less based on all structural units, and the content of structural units derived from an α-olefin having 2 to 4 carbon atoms is less than 1 mol% based on all structural units. .

Examples of α-olefins having 8 or more carbon atoms include 1-octene, 1-decene, 1-hexadecene, 1-heptadecene, 1-octadecene and the like. Polymer B may contain a structural unit derived from one type of α-olefin having 8 or more carbon atoms, and may contain structural units derived from two or more types of α-olefin having 8 or more carbon atoms. You can

The content of structural units derived from 4-methyl-1-pentene contained in polymer B is 50 mol % to 100 mol % of all structural units. When the polymer B is a copolymer, the content of structural units derived from 4-methyl-1-pentene contained in the polymer B is 50 mol% to 99 mol% with respect to all structural units. may be from 60 mol % to 98 mol %.

The content of structural units derived from α-olefins having 8 or more carbon atoms that can be contained in the polymer B is 10 mol% or less, and 0.1 mol% to 5 mol%, based on the total structural units. may be present, and may be 0.5 mol % to 3 mol %.

The content of structural units derived from α-olefins having 2 to 4 carbon atoms that may be contained in the polymer B is less than 1 mol% and 0 mol% to 0.5 mol% with respect to all structural units. or 0 mol % to 0.3 mol %.

Polymer B is a structural unit derived from a polymerizable compound other than 4-methyl-1-pentene, an α-olefin having 8 or more carbon atoms, and an α-olefin having 2 to 4 carbon atoms (hereinafter referred to as "other structural units unit B"). The content of other structural units B that can be contained in the polymer B may be 10 mol % or less, or 5 mol % or less, relative to the total structural units.

The MFR of polymer B (measured at a temperature of 260° C. and a load of 5.0 kg according to ASTM D1238) is not particularly limited as long as it can be melt-spun, and is 5 g/10 min to 600 g/10 min. may be from 70 g/10 minutes to 500 g/10 minutes, or from 70 g/10 minutes to 400 g/10 minutes.

The density of polymer B is not particularly limited as long as it can be melt-spun, and may be 0.820 g/cm ³ to 0.870 g/cm, or 0.825 g/cm ³ to 0.850 g/cm ³ . may
The density of polymer B can be measured by the method described in Examples below.

The melting point of the polymer B is not particularly limited as long as it can be melt-spun, and may be 200°C or higher, or 200°C to 250°C.
The melting point of polymer B can be measured by the method described in Examples below.

Polymer B can be obtained by the same method as for copolymer A described above.

As the α-olefin polymer having a content of structural units derived from 4-methyl-1-pentene of less than 50 mol%, the content of structural units derived from α-olefins other than 4-methyl-1-pentene is 50 mol % or more (hereinafter also referred to as “specific α-olefin polymer”).

Specific α-olefin polymers include, for example, ethylene-based polymers and propylene-based polymers, and propylene-based polymers are preferable from the viewpoint of excellent spinnability, drawing processability, and the like.

Ethylene-based polymers include ethylene random copolymers such as ethylene/propylene random copolymers, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, and ethylene/1-butene random copolymers. etc.

Examples of the propylene-based polymer include propylene homopolymers, propylene random copolymers which are copolymers of propylene as the main component and one or more types of α-olefins as subcomponents, among others. , propylene homopolymer is preferred. In the propylene random copolymer, the content of α-olefin-derived structural units is preferably 1 mol% to 10 mol%, more preferably 1 mol% to 6 mol%, based on the total structural units. is more preferred.

The α-olefin used for the copolymerization of the propylene random copolymer is preferably an α-olefin having 2 or more carbon atoms (excluding propylene), more preferably an α-olefin having 2 or 4 to 8 carbon atoms. Specific examples of α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1 -pentene, 4-methyl-1-pentene, 4-methyl-1-hexene and the like.

The MFR of the propylene-based polymer (measured at a temperature of 230° C. and a load of 2.16 kg according to ASTM D1238) is not particularly limited as long as it can be melt-spun, and ranges from 10 g/10 minutes to 800 g/10 minutes. 20 g/10 minutes to 100 g/10 minutes.

The density of the propylene-based polymer is not particularly limited as long as it can be melt-spun, and may be 0.900 g/cm ³ to 0.945 g/cm ³ , or 0.910 g/cm ³ to 0.940 g/cm ³ . may be
The density of the propylene-based polymer can be measured by the method described in Examples below.

The melting point of the propylene-based polymer is not particularly limited as long as it can be melt-spun, and may be 125°C or higher, or 125°C to 165°C.
The melting point of the propylene-based polymer can be measured by the method described in Examples below.

When a propylene/α-olefin random copolymer is used as the propylene-based polymer, its melting point (Tm) is preferably 153°C or less, more preferably 125°C to 150°C.
When a propylene homopolymer is used as the propylene-based polymer, its melting point (Tm) is preferably 155°C or higher, more preferably 157°C to 165°C.

The propylene-based polymer is usually a Ziegler-Natta type catalyst in which a so-called titanium-containing solid transition metal component and an organic metal component are combined, or a periodic table group 4 to group 6 having at least one cyclopentadienyl skeleton. It can be obtained by homopolymerizing propylene or copolymerizing propylene and a small amount of α-olefin by slurry polymerization, gas phase polymerization, or bulk polymerization using a metallocene catalyst consisting of a transition metal compound and a co-catalyst component.

The α-olefin polymer (excluding copolymer A) is preferably at least one selected from the group consisting of the aforementioned polymer B and propylene-based polymers.

《Other thermoplastic resins》
Other thermoplastic resins include, but are not limited to, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamides such as nylon-6, nylon-66, and poly-metaxylene adipamide, polyvinyl chloride, and polyimides. , ethylene/vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, and ionomer.
The other thermoplastic resin may consist of one kind or may be a mixture of two or more kinds.

(Additive)
Fibers contained in the spunbond nonwoven fabric of the present disclosure may contain, as optional components, antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antifog agents, lubricants, dyes, pigments, natural oils, and synthetic oils. , various known additives such as wax.
The nonwoven fabrics of the present disclosure may optionally contain other ingredients. Other components include, for example, antioxidants, heat stabilizers, weather stabilizers, antistatic agents, slip agents, antifog agents, lubricants, dyes, pigments, light stabilizers, antiblocking agents, dispersants, and nucleating agents. , softeners, water repellents, fillers, natural oils, synthetic oils, waxes, antibacterial agents, preservatives, matting agents, antirust agents, fragrances, antifoaming agents, antifungal agents, insect repellents, etc. and additives. These other components may be contained inside the fibers contained in the spunbond nonwoven fabric, or may be attached to the surface of the fibers.

The average fiber diameter of the fibers contained in the spunbond nonwoven fabric of the present disclosure is not particularly limited, and is preferably 10 μm to 50 μm, more preferably 12 μm to 30 μm.
The average fiber diameter of fibers can be measured by the method described in Examples below.

The basis weight of the spunbond nonwoven fabric of the present disclosure is not particularly limited, and is preferably 5 g/m ² to 100 g/m ² , more preferably 10 g/m ² to 50 g/m ² .
The basis weight of the spunbond nonwoven fabric can be measured by the method described in Examples below.

The thickness of the spunbond nonwoven fabric of the present disclosure is not particularly limited, and is preferably 0.05 mm to 10.0 mm, more preferably 0.07 mm to 5.0 mm, and 0.10 mm to 1.0 mm. It is even more preferable to have
The thickness of the spunbond nonwoven fabric can be measured by the method described in Examples below.

The spunbond nonwoven fabric may have a crimped portion and a non-crimped portion. The area ratio of the crimped portion is preferably 5% to 20%, more preferably 6% to 19%. The area ratio of the crimped portion was obtained by taking a test piece of 10 mm × 10 mm from the spunbond nonwoven fabric, observing the contact surface of the test piece with the embossing roll with an electron microscope (magnification: 100 times), and observing the span It is defined as the ratio of the area of the thermocompression-bonded portion to the area of the bonded nonwoven fabric. Further, the area ratio of the protrusions formed on the embossing roll that can form the crimping portion is also referred to as "embossed area ratio".

The spunbond nonwoven fabric of the present disclosure may have a structure in which two or more layers of the spunbond nonwoven fabric of the present disclosure are laminated, and at least one layer of the spunbond nonwoven fabric of the present disclosure and a nonwoven fabric other than the spunbond nonwoven fabric of the present disclosure , knitted fabric, woven fabric, paper, film (including sheet), etc. may be laminated in any order.
Nonwoven fabrics other than the spunbond nonwoven fabric of the present disclosure include, for example, spunbond nonwoven fabrics (excluding spunbond nonwoven fabrics of the present disclosure), meltblown nonwoven fabrics, wet laid nonwoven fabrics, spunlace nonwoven fabrics, dry nonwoven fabrics, dry pulp nonwoven fabrics, air-laid nonwoven fabrics, Various known short-fiber nonwoven fabrics and long-fiber nonwoven fabrics (for example, long-fiber cellulose nonwoven fabrics), such as water-jet nonwoven fabrics, flash-spun nonwoven fabrics, open-fiber nonwoven fabrics, needle-punched nonwoven fabrics, and the like, can be used.

When laminating two or more layers of the spunbond nonwoven fabric of the present disclosure, when laminating at least one layer of the spunbond nonwoven fabric of the present disclosure and a material other than the spunbond nonwoven fabric in any order, each layer is laminated ( For example, the method of bonding is not particularly limited. For example, thermal embossing, thermal fusion bonding such as ultrasonic fusion, mechanical entangling methods such as needle punching and water jetting, methods using adhesives such as hot melt adhesives and urethane adhesives, extrusion lamination, etc. , various known methods can be adopted.

<Method for producing spunbond nonwoven fabric>
A method for manufacturing the spunbond nonwoven fabric of the present disclosure will be described below. The spunbond nonwoven fabric of the present disclosure described above may be produced by the method for producing a spunbond nonwoven fabric of the present disclosure below, or may be produced by another production method.

The method for producing a spunbond nonwoven fabric of the present disclosure is a method for producing a spunbond nonwoven fabric by discharging a thermoplastic resin or a thermoplastic resin composition containing the thermoplastic resin from a spinning nozzle and melt spinning, wherein the thermoplastic resin is a copolymer A containing 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% or more of structural units derived from an α-olefin having 2 to 4 carbon atoms. The draft ratio, which is the ratio of the fastest yarn speed to the yarn speed during ejection, is less than 2,000.

A copolymer A such as a copolymer of 4-methyl-1-pentene and propylene containing 50 mol% or more of structural units derived from 4-methyl-1-pentene, which is an example of the copolymer A, is spunbonded. When attempting to make nonwoven fabrics, it is difficult to produce spunbond nonwoven fabrics under the conditions typical of making spunbond nonwoven fabrics.

On the other hand, in the method for producing a spunbond nonwoven fabric of the present disclosure, when the thermoplastic resin or the like containing the copolymer A is melt-spun, the draft ratio, which is the ratio of the fastest yarn speed to the yarn speed during ejection, is less than 2000. . Thereby, even when the copolymer A is used for the production of the spunbond nonwoven fabric, the spunbond nonwoven fabric can be suitably produced.

The configuration of the method for producing a spunbond nonwoven fabric of the present disclosure will be described below with reference to FIGS. 1 and 2. FIG. The description of the configuration common to the spunbond nonwoven fabric of the present disclosure is omitted.

(Method 1 for producing spunbond nonwoven fabric)
First, a method 1 for producing a spunbond nonwoven fabric will be described with reference to FIG. In the manufacturing method 1 of the spunbond nonwoven fabric of the present disclosure, as an example, it is possible to use the manufacturing apparatus shown in FIG. In some embodiments, the cooling chamber may be open. The nonwoven fabric manufacturing apparatus shown in FIG. 1 is an apparatus for manufacturing a spunbond nonwoven fabric containing monocomponent fibers using a thermoplastic resin composed of copolymer A or a thermoplastic resin composition containing the thermoplastic resin. .

The nonwoven fabric manufacturing apparatus includes a spinning section 11 that melt-spun a molten thermoplastic resin or a thermoplastic resin composition, cools and stretches the melt-spun continuous fiber group 22, and collects the stretched continuous fiber group 22. and a suction unit 39 for efficiently collecting the continuous fiber group 22 on the moving collection member 51 .

The nonwoven fabric manufacturing apparatus includes an embossing roll and a flat roll for entangling the nonwoven web 43 composed of the collected continuous fiber groups 22 by thermocompression bonding, and a winder for winding the spunbond nonwoven fabric after thermocompression bonding. may

The method of entangling the nonwoven web is not limited to the method of heat embossing treatment using the embossing roll described above, and includes a method of fusing with ultrasonic waves, a method of entangling fibers using a water jet, and a method of entangling fibers using hot air. There are various methods such as a through fusion method and a method using a needle punch.

The spinning unit 11 includes an extruder 32 that extrudes the first thermoplastic polymer, a spinneret 34 that ejects a molten thermoplastic resin or thermoplastic resin composition from a spinning nozzle, and the spinning nozzle of the spinneret 34. cooling chamber 38C for cooling the continuous fiber group 22, cooling air supply units 38A and 38B for supplying the cooling air 36, and drawing unit 38D for drawing the continuous fiber group 22.

In the spinning section 11 , the thermoplastic resin or thermoplastic resin composition is extruded and introduced into the spinneret 34 . Next, the molten thermoplastic resin or thermoplastic resin composition is discharged from the spinning nozzle of the spinneret 34 and melt-spun. The melting temperature of the thermoplastic resin or the like is not particularly limited as long as the thermoplastic resin or the like can be melted.

The melt-spun continuous fiber group 22 is introduced into the cooling chamber 38C. The continuous fiber group 22 is cooled by the cooling air 36 supplied from one or both of the cooling air supply section 38A and the cooling air supply section 38B. The cooled continuous fiber group 22 is introduced into the drawing section 38D provided downstream of the cooling chamber 38C. The extending portion 38D is provided like a bottleneck. The continuous fiber group 22 introduced into the drawing section 38D is drawn by increasing the speed of the cooling air in the bottleneck.

When melt-spinning a thermoplastic resin or the like, the draft ratio, which is the ratio of the fastest yarn speed to the yarn speed at the time of ejection, is less than 2000. The draft ratio can be adjusted to 2000 or more by adjusting the flow rate of the cooling air, the flow velocity of the cooling air, the hole diameter of the spinning nozzle, the single hole discharge amount, and the like. For example, there is a tendency that the draft ratio can be adjusted to be small by reducing the flow rate of the cooling air, the flow velocity of the cooling air, and the like.

The draft ratio is the fastest yarn speed divided by the yarn speed at ejection. The yarn speed at the time of ejection can be calculated from the nozzle hole diameter, the ejection amount of the thermoplastic resin or the like from the spinning nozzle, and the density of the thermoplastic resin or the like. The yarn speed is maximized at the drawn portion 38D. Therefore, the fastest yarn speed can be measured at the drawing section 38D, for example, by the laser Doppler method as described in Examples below.

The draft ratio may be, for example, 400-1500 or 500-1300. The draft ratio may be from 400 to 1000, or from 500 to 800, from the viewpoint of suitably producing a spunbond nonwoven fabric containing monocomponent fibers.

The drawn continuous fiber group 22 is dispersed and collected on the moving collecting member 51 . The dispersed continuous fiber group 22 is efficiently collected on the moving collecting member 51 by the suction unit 39 provided below the collecting surface of the moving collecting member 51, and contains monocomponent fibers. A nonwoven web 43 is formed.

(Method 2 for producing spunbond nonwoven fabric)
Next, method 2 for producing a spunbond nonwoven fabric will be described with reference to FIG. Method 2 for producing a spunbond nonwoven fabric differs from Method 1 for producing a spunbond nonwoven fabric described above in that it is a method for producing a spunbond nonwoven fabric containing composite fibers. In addition, the description is abbreviate|omitted about the matter which is common in the manufacturing method 1 of the above-mentioned spunbond nonwoven fabrics.

In the method 2 for producing a spunbond nonwoven fabric, a first thermoplastic resin composed of a copolymer A, or a first thermoplastic resin composition containing a first thermoplastic resin, and a thermoplastic other than the copolymer A A second thermoplastic resin that is a resin (preferably an α-olefin polymer (excluding copolymer A)) or a second thermoplastic resin composition containing a second thermoplastic resin is used.

The spinning unit 12 includes a first extruder 32A that extrudes a first thermoplastic resin or the like, a second extruder 32B that extrudes a second thermoplastic resin or the like, a molten first thermoplastic polymer and A spinneret 34 for melt-spinning the second thermoplastic polymer, a cooling chamber 38C for cooling the continuous fiber group 23 melt-spun from the spinneret 34, and cooling air supply units 38A and 38B for supplying cooling air 36. , and a drawing portion 38D for drawing the continuous fiber group 23 .

A first thermoplastic resin or the like is extruded from the first extruder 32A, a second thermoplastic resin or the like is extruded from the second extruder 32B, and the continuous fiber group 23, which is a composite fiber, is formed by conjugate spinning. can get. By appropriately changing the cross-sectional shape of the spinning nozzle that discharges the first thermoplastic resin, etc. and the second thermoplastic resin, etc., a core-sheath type such as a side-by-side type, a concentric core-sheath type, or an eccentric core-sheath type, etc. conjugate fibers can be produced. Further, by appropriately changing the cross-sectional shape of the spinning nozzle, it is possible to adjust the volume ratio of the core portion and the sheath portion in the core-sheath type conjugate fiber, which is a concentric core-sheath type or an eccentric core-sheath type.

The draft ratio may be, for example, 400-1500 or 500-1300. From the viewpoint of suitably producing a spunbonded nonwoven fabric containing composite fibers, preferably sheath-core type composite fibers that are concentric core-sheath type or eccentric core-sheath type, the draft ratio may be 600 to 1500, or 700. ~1300.
Further, from the viewpoint of reducing the average fiber diameter of the conjugate fiber, the draft ratio may be 400 or more and less than 2000, or may be 700 to 1900.

The drawn continuous fiber group 23 is dispersed and collected on the moving collecting member 51 . Then, the dispersed continuous fiber group 23 is efficiently collected on the moving collecting member 51 by the suction unit 39 provided below the collecting surface of the moving collecting member 51, and the waste including the conjugate fiber is collected. A woven web 44 is formed.

Hereinafter, the embodiments of the present invention will be described more specifically based on examples, but the present invention is not limited to these examples, which are one embodiment of the present invention.
Physical properties and the like in Examples and Comparative Examples were measured by the following methods.

(1) basis weight [g/m ² ]
Ten test pieces of 100 mm (machine direction: MD) x 100 mm (direction perpendicular to machine direction: CD) were sampled from the obtained nonwoven fabric. Ten test pieces were collected in the CD direction. Then, the mass [g] was measured for each test piece taken under an environment of 23° C. and a relative humidity of 50% using a top-pan electronic balance (manufactured by Kensei Kogyo Co., Ltd.). An average value of the mass of each test piece was obtained. The obtained average value was converted to mass [g] per 1 m ² , rounded off to the second decimal place, and determined as basis weight [g/m ² ] of each nonwoven fabric sample.

(2) Thickness [mm]
Ten test pieces of 100 mm (MD)×100 mm (CD) were taken from the obtained nonwoven fabric. The test piece was taken from the same place as the test piece for basis weight measurement. Then, using a load-type thickness gauge (manufactured by Ozaki Seisakusho Co., Ltd.), the thickness [mm] was measured with a load of 7 g/cm ² according to the method described in JIS L 1096:2010 for each sample sample. It was measured. The average value of the thickness of each test piece was determined. The thickness [mm] of each nonwoven fabric sample was obtained by rounding off to the third decimal place.

(3) Average fiber diameter (μm)
The obtained nonwoven fabric was photographed at a magnification of 200 using an electron microscope (S-3500N manufactured by Hitachi, Ltd.). From the photographs taken, the diameter (width) of the fibers was measured, and the imaging and diameter measurement were repeated until the total number of fibers exceeded 100 (n=100). The arithmetic average value of the diameters of the obtained fibers was defined as the average fiber diameter (μm).

(4) Stress relaxation rate (%)
A test piece having a width of 50 mm (CD) and a length of 200 mm (MD) was taken from the obtained nonwoven fabric. Using a tensile tester (Shimadzu Autograph AGS-J), measure the stress (initial stress) when the test piece is stretched by 10% under the conditions of a chuck distance of 100 mm and a head speed of 300 mm / min. The elongation was held for 120 seconds, and the change in stress during that time was also measured. Then, the stress relaxation rate (%) was calculated from the difference between the initial stress and the stress 60 seconds after elongation.

(5) Evaluation of Peel Strength Two test pieces each having a width of 50 mm (CD) and a length of 100 mm (MD) were taken from the obtained nonwoven fabric. These two sheets were superimposed to form a two-layer test piece having a width of 50 mm (CD) and a length of 100 mm (MD). A 50 mm wide by 50 mm long, 5 kg weight was then placed on one side of the two-layer specimen. With the weight placed on the two-layer test piece, it was allowed to stand in an air-drying oven at 50°C for 20 minutes, after which the two-layer test piece was taken out of the oven and left to stand at 25°C for 5 minutes. Next, the weight was moved from the two-layer test piece, the test piece on the side where the weight was not placed was peeled off, and the peeled test piece was gripped by the upper and lower chucks of the tensile tester. The maximum load (N) was measured under the conditions of a tensile speed of 300 mm/min and 23°C. This was repeated three times, and the average maximum load was obtained.
The average value of the obtained maximum load (N) was evaluated for peel strength in light of the following evaluation criteria. When the evaluation is A or B, it means that the peel strength is low and the blocking resistance is excellent.
-Evaluation criteria-
A: The portion where the weight was installed peeled off naturally, and the peel strength could not be measured.
B: Average value of peel strength is less than 1.0N.
C: The average peel strength is 1.0 N or more, or the test piece breaks without peeling.

[Synthesis of copolymer A]
300 mL of normal hexane (dried over activated alumina in a dry nitrogen atmosphere) and 450 mL of 4-methyl-1-pentene were charged at 23° C. into a 1.5-liter SUS autoclave equipped with a stirring blade that had been sufficiently purged with nitrogen. . The autoclave was charged with 0.75 mL of a 1.0 mmol/mL toluene solution of triisobutylaluminum (TIBAL), and a stirrer was turned.
Next, the autoclave was heated to an internal temperature of 60° C. and pressurized with propylene so that the total pressure was 0.40 MPa (gauge pressure). Subsequently, prepared in advance, 1 mmol of methylaluminoxane in terms of Al, diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium 0.34 mL of a toluene solution containing 0.01 mmol of dichloride was pressurized into the autoclave with nitrogen to initiate polymerization. During the polymerization reaction, the temperature inside the autoclave was adjusted to 60°C. After 60 minutes from the initiation of polymerization, 5 mL of methanol was pressurized into the autoclave with nitrogen to stop the polymerization, and the autoclave was depressurized to atmospheric pressure. Acetone was poured into the reaction solution while stirring.
The powdery polymer containing the obtained solvent was dried at 100° C. under reduced pressure for 12 hours. The obtained copolymer A weighed 36.9 g, and the structural unit derived from 4-methyl-1-pentene in the copolymer A was 72 mol%, and the structural unit derived from propylene was 28 mol%. rice field.
The resulting copolymer A had an MFR (measured according to ASTM D1238 at a temperature of 230°C and a load of 2.16 kg) of 11 g/10 minutes, and a density of 0.840 g/10, measured as follows. cm ³ , and an attempt to determine the melting point as follows showed no melting point.

[Synthesis of polymer B]
According to the method described in the examples of JP-A-2017-074775, the polymer A-1 of JP-A-2017-074775 was synthesized to obtain a polymer B. The constituent units derived from 4-methyl-1-pentene in Polymer B accounted for 97.8 mol%, and the constituent units derived from 1-decene accounted for 2.2 mol%.
For the obtained polymer B, MFR was measured according to the method described in Examples of JP-A-2017-074775, and density and melting point were measured according to the following methods. Polymer B had an MFR (measured according to ASTM D1238 at a temperature of 260°C and a load of 5.0 kg) of 100 g/10 min, a density of 0.833 g/cm ³ and a melting point of 232°C. .

[Preparation of propylene homopolymer]
In addition to the copolymer A and polymer B described above, a propylene homopolymer (PP in the table) was prepared as a thermoplastic resin. The propylene homopolymer has an MFR (measured according to ASTM D1238 at a temperature of 230°C and a load of 2.16 kg) of 60 g/10 min and a density of 0.910 g/ ^cm3 measured as follows. and the melting point measured as follows was 160°C.

(density)
The density of copolymer A, the density of polymer B and the density of propylene homopolymer were measured according to JIS K7112 (density gradient tube method). This density (kg/m ³ ) was used as an index of lightness.
Note that the melt density is converted from the PVT measurement.

(Melting point of copolymer A and melting point of propylene homopolymer)
The melting point (Tm) of the copolymer A and the melting point (Tm) of the propylene homopolymer were measured using a differential scanning calorimeter (DSC220C model, manufactured by Seiko Instruments Inc.) as a measuring device. About 5 mg of copolymer A was sealed in an aluminum measuring pan and heated from room temperature to 200°C at 10°C/min. It was held at 200°C for 5 minutes and then cooled to -50°C at 10°C/min. After holding at −50° C. for 5 minutes, heating was performed for the second time up to 200° C. at 10° C./min, and the melting point (Tm) was calculated from the apex of the crystal melting peak of the calorimetric curve during this second heating.

(Melting point of polymer B)
The melting point (Tm) of polymer B was measured using a differential scanning calorimeter (DSC220C model, manufactured by Seiko Instruments Inc.) as a measuring device. About 5 mg of Polymer B was sealed in an aluminum measuring pan and heated from room temperature to 290°C at 100°C/min. It was held at 290°C for 5 minutes and then cooled to -100°C at 10°C/min. The melting point (Tm) was calculated from the apex of the crystal melting peak of the calorimetric curve when heating from −100° C. to 290° C. at 10° C./min.

[Example 1]
A spunbond nonwoven fabric was produced by a spunbond method using a spunbond nonwoven fabric production apparatus equipped with one extruder. A nozzle for monocomponent fibers was used as the nozzle. Copolymer A was melted at a molding temperature of 250° C. by an extruder. The melted copolymer A is discharged from a spinneret having four 0.6 mmφ nozzles per 1 cm ² at 0.6 g / min per hole, and cooling air is supplied to the cooling chamber and at the drawing section. The fibers were drawn and melt-spun by a spunbond method. A spunbond nonwoven fabric having a basis weight of 20 g/m ² was produced by heat embossing after the drawn fibers were deposited on the collecting surface.

Yarn speed was measured by the laser Doppler method in the drawing section. A PIN-30N model manufactured by Onitsuka Glass Co., Ltd. was used as a laser oscillator. The laser had a wavelength of 10.6 μm, a nominal rated power of 30 W, a beam divergence of 1.0 mrad, and a random polarization state. A laser power meter AN/2 type manufactured by Ophir was used on the light receiving side. From the fastest yarn speed obtained and the yarn speed at the time of ejection calculated from the following equation, the draft ratio was calculated by the following equation.
Thread speed at the time of ejection = single hole ejection amount / [(nozzle diameter / 2) ² x π x density of resin]
Draft ratio = fastest yarn speed / yarn speed at discharge

[Examples 2 and 3 and Comparative Examples 1 to 4]
In Example 1, the nozzle diameter and single-hole discharge rate were changed as shown in Table 1, and the fastest yarn speed was adjusted by adjusting the amount and speed of the cooling air. A spunbond nonwoven fabric was produced in the same manner as in Example 1 except for these changes.

[Example 4]
A spunbond nonwoven fabric was produced by a spunbond method using a spunbond nonwoven fabric production apparatus equipped with two extruders. A concentric core-sheath type nozzle was used as the nozzle. Copolymer A and propylene homopolymer were each melted at a molding temperature of 250° C. by two extruders. The ratio of the core to the sheath (core: sheath ) was adjusted. The melted copolymer A and propylene homopolymer are discharged from a spinneret having four 0.6 mmφ nozzles per 1 cm ² at 0.6 g/min per hole, and cooling air is supplied to the cooling chamber. Then, the fiber was drawn at the drawing section, and composite melt spinning was performed by the spunbond method. A spunbond nonwoven fabric having a basis weight of 20 g/m ² was produced by heat embossing after the drawn fibers were deposited on the collecting surface. The fibers contained in the spunbonded nonwoven fabric obtained in Example 4 are concentric core-sheath type conjugate fibers having a core made of propylene homopolymer and a sheath made of copolymer A. The core: The sheath was 50:50.

[Examples 5 to 8]
In Example 4, the same as Example 4 except that the type of resin constituting the core and the sheath, the ratio of the core and the sheath (core:sheath), and the melting temperature were changed as shown in Table 1. Then, a spunbonded nonwoven fabric containing concentric core-sheath type composite fibers was produced.

[Comparative Example 5]
A spunbonded nonwoven fabric was produced in the same manner as in Example 1, except that the resin type, single-hole discharge rate, and melting temperature were changed as shown in Table 1.

[Comparative Example 6]
A meltblown nonwoven fabric was produced by a meltblown method using a meltblown nonwoven fabric production apparatus equipped with one extruder. A nozzle for monocomponent fibers was used as the nozzle. Copolymer A was melted at a molding temperature of 250° C. by an extruder. Heated air (temperature: 250 ° C., flow rate: 240 Nm ³ /h/m), and melt spinning was performed by the meltblown method. The fibers were deposited on the collecting surface to produce a meltblown nonwoven fabric with a basis weight of 20 g/m ² .

The resulting spunbond nonwoven fabric and meltblown nonwoven fabric were measured for draft ratio, basis weight, thickness, average fiber diameter and stress relaxation rate by the methods described above, and the peel strength was evaluated by the methods described above. The results are shown in Tables 1 and 2.

As shown in Comparative Examples 1 to 4 in Table 2, when the draft ratio in producing the spunbond nonwoven fabric was 2000 or more, the spinning could not be performed and the spunbond nonwoven fabric could not be produced.
On the other hand, as shown in Examples 1 to 8 in Table 1, it was possible to produce a spunbond nonwoven fabric when the draft ratio was less than 2000 when producing the spunbond nonwoven fabric.
Furthermore, as shown in Table 1, the spunbonded nonwoven fabric containing concentric core-sheath type conjugate fibers whose core portion is made of copolymer A was evaluated to be good in peel strength and excellent in blocking resistance. It was confirmed that

Claims (9)

A copolymer A containing 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% or more of structural units derived from an α-olefin having 2 to 4 carbon atoms as a constituent component A spunbond nonwoven fabric containing fibers to 2. The spunbond nonwoven fabric according to claim 1, wherein the fibers are core-sheath type conjugate fibers having a core and a sheath. 3. The spunbond nonwoven fabric according to claim 2, wherein the core contains the copolymer A. 4. The spunbond nonwoven fabric according to claim 2 or 3, wherein the sheath contains an α-olefin polymer (excluding the copolymer A). The α-olefin polymer (excluding the copolymer A) contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and is derived from an α-olefin having 8 or more carbon atoms. The content of structural units is 10 mol% or less based on all structural units, and the content of structural units derived from α-olefins having 2 to 4 carbon atoms is less than 1 mol% based on all structural units. 5. The spunbond nonwoven fabric according to claim 4, which is at least one selected from the group consisting of Coalescing B and a propylene-based polymer. 6. The spunbond nonwoven fabric according to any one of claims 2 to 5, wherein the volume ratio of the sheath to the core (core:sheath) is 30:70 to 90:10. 2. The spunbond nonwoven fabric of claim 1, wherein said fibers are monocomponent fibers. The spunbond nonwoven fabric according to any one of claims 1 to 7, wherein the fibers have an average fiber diameter of 10 µm to 50 µm. A method for producing a spunbond nonwoven fabric by discharging a thermoplastic resin or a thermoplastic resin composition containing the thermoplastic resin from a spinning nozzle and melt spinning,
The thermoplastic resin contains 50 mol% or more of structural units derived from 4-methyl-1-pentene and 1 mol% or more of structural units derived from an α-olefin having 2 to 4 carbon atoms. including a polymer A,
A method for producing a spunbond nonwoven fabric, wherein the draft ratio, which is the ratio of the fastest yarn speed to the yarn speed during ejection, is less than 2,000.

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