JP2000160463A - Soft non-woven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a soft non-woven fabric suitable for a soft hygienic material, packaging material, clothes, etc., excellent in touch feeling of its surface by constituting the non-woven fabric by using fibers consisting of a polyolefin-based thermoplastic resin containing an olefin-based elastomer. SOLUTION: This soft non-woven fabric is constituted by using a composite fibers consisting of a polyolefin-based thermoplastic resin such as a single polymer of propylene containing an olefin-based elastomer, e.g. an ethylene/α-olefin copolymer, in >=3 wt.%, a propylene/ethylene random copolymer, etc., and containing >=3 wt.%, preferably 5-30 wt.% above olefin-based elastomer in its core part in the case of having a sheath core structure and in its one side in the case of side by side, piling the non-woven fabric at least 2 layers and bonding for one unit with a heat-emboss process. Also, it is preferable to form a laminated material of the soft non-woven fabric with a ventilating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible nonwoven fabric and a laminate, which are excellent in flexibility and surface tactile sensation and have high friction fastness. The present invention relates to a flexible nonwoven fabric and a laminate useful for industrial materials.

[0002]

2. Description of the Related Art In recent years, nonwoven fabrics have been used in a wide range of applications such as medical and hygiene materials, industrial use, and the like. For example, non-woven fabrics used for medical and hygiene materials such as disposable diapers are used for portions directly in contact with human skin. Therefore, non-woven fabrics having further excellent flexibility and surface feel are required. Further, nonwoven fabrics used as industrial materials such as packaging materials are also required to be more flexible and have an excellent tactile sensation.

[0003] By the way, nonwoven fabrics used for medical and sanitary materials, industrial materials, and the like have been replaced with polyethylene fibers and propylene from conventional polypropylene fibers in order to further improve flexibility and surface feel. Nonwoven fabrics have been proposed or implemented in which fibers made of a copolymer of another monomer such as ethylene or a composite fiber made of polyethylene and polypropylene are used as constituent fibers.

[0004]

However, if low-density polyethylene is used for the purpose of improving the flexibility of the polyethylene fiber, there is a problem that stickiness occurs and the strength is reduced. In addition, since a fiber made of a copolymer of propylene and another monomer such as ethylene has an upper limit in the content of ethylene, it is difficult to obtain desired flexibility. Further, a composite fiber composed of polyethylene and polypropylene, for example, a composite fiber having a core-sheath structure, has a weight component ratio (S / C) of the core part (C) composed of polypropylene and the sheath part (S) composed of polyethylene being 5%. / 5 to 1/9
However, when the number is increased, there is a problem that flexibility is impaired.

Accordingly, a first object of the present invention is to provide a flexible nonwoven fabric which is excellent in flexibility and surface tactile sensation, and is particularly suitable for industrial materials such as medical and sanitary materials such as disposable diapers, packaging materials and clothing. Is to provide.

A second object of the present invention is to provide a laminate using the flexible nonwoven fabric.

[0007]

In order to achieve the first object, the present invention provides a flexible nonwoven fabric characterized by containing fibers made of a polyolefin thermoplastic resin containing an olefin elastomer. It is.

[0008] The present invention also relates to a nonwoven fabric comprising a core-sheath type composite fiber made of a polyolefin thermoplastic resin,
An object of the present invention is to provide a flexible nonwoven fabric, wherein the sheath of the core-sheath type composite fiber contains an olefin-based elastomer.

Further, the present invention provides a nonwoven fabric comprising a side-by-side conjugate fiber composed of a polyolefin-based thermoplastic resin, wherein at least one component of the side-by-side conjugate fiber contains an olefin-based elastomer. The present invention provides a nonwoven fabric.

Further, the present invention provides at least two nonwoven fabric layers containing fibers made of a polyolefin-based thermoplastic resin, wherein at least one fiber constituting the nonwoven fabric layer contains an olefin-based elastomer, and each layer has a hot embossed layer. The present invention provides a flexible nonwoven fabric characterized by being bonded by:

In order to achieve the second object, the present invention provides a laminate of the above-mentioned flexible nonwoven fabric and a breathable film.

Hereinafter, the flexible nonwoven fabric of the present invention (hereinafter referred to as “nonwoven fabric of the present invention”) will be described in detail.

The nonwoven fabric of the present invention contains fibers made of a polyolefin thermoplastic resin containing an olefin elastomer. As the polyolefin-based thermoplastic resin which is a main component of the fibers constituting the nonwoven fabric, propylene, ethylene, butene or a homopolymer of 4-methyl-1-pentene, propylene, ethylene or butene and other monomers And the like. The copolymer may be a random copolymer or a block copolymer. Other monomers include ethylene, butene, and the like. Further, the constituent fibers of the nonwoven fabric of the present invention may be composed of one of these polyolefin-based thermoplastic resins or a combination of two or more thereof. Among these, propylene homopolymers and propylene / ethylene random copolymers are preferred because of their good spinnability.

The polyolefin-based thermoplastic resin preferably has an MFR of 10 to 100 g / 10 minutes, particularly preferably an MFR of 30 to 60 g / 10 minutes, from the viewpoint of spinnability. Further, from the viewpoint of spinnability, the polyolefin-based thermoplastic resin preferably has a weight average molecular weight (Mw) showing a molecular weight distribution and a number average molecular weight (Mn) ratio (Mw / Mn) of 3 or less. Those having Mw / Mn of 2.5 or less are preferred.

The constituent fibers of the nonwoven fabric of the present invention contain an olefin-based elastomer. Examples of the olefin-based elastomer include an ethylene / α-olefin copolymer.

A specific example of the ethylene / α-olefin copolymer is a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. 3-20 carbon atoms
As the α-olefin, propylene, 1-butene,
Examples thereof include 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. Among these, 1-butene is particularly preferred.

In the ethylene / α-olefin copolymer, 55 to 99.9 mol% of a structural unit derived from ethylene and 0.1 to 45 mol of a structural unit derived from an α-olefin having 3 to 20 carbon atoms are used. % Is preferable, and in particular, a constituent unit derived from ethylene is 85 to 95%.
Mol%, 5 to 1 structural units derived from α-olefin
Those containing 5 mol% are preferred.

The ethylene / α-olefin copolymer has a density (d) of 0.850 to 0.950 g / cm.
³ , preferably 0.860 to 0.940 g / cm ³ , more preferably 0.870 to 0.930 g / cm ³ . In the present invention, the density (d) of the ethylene / α-olefin copolymer is the density (d) in the present invention, and the density (d) is the strand obtained at a melt flow rate (MFR) measurement at 190 ° C. under a load of 2.16 kg. , 120 ° C. for 1 hour, slowly cooled to room temperature over 1 hour, and measured with a density gradient tube.

The melt flow rate (MFR) of the ethylene / α-olefin copolymer at 190 ° C. under a load of 2.16 kg is 0.5 to 100 g / 10
Min, preferably 15 to 50 g / 10 min. The crystallinity measured by X-ray diffraction is 5 to 40%, preferably 7 to 30%.

The fiber constituting the nonwoven fabric of the present invention may be a single-layer fiber in which the whole fiber is homogeneously formed of one or more resins, or may be composed of two or more different resin components. It may be a composite fiber formed from portions, or may be a combination of these single-layer fibers and composite fibers. As a composite fiber, 1
A core-sheath type composite fiber having a fiber cross-sectional structure having a core portion composed of one or more resin components and a sheath portion formed of a resin component different from the core portion outside the core portion; A side-by-side type conjugate fiber having a structure in which one side portion A composed of two or more resin components and a resin component different from the one side and having the other side portion arranged in parallel in a fiber cross section is exemplified. The core-sheath type composite fiber has a form in which a core portion is wrapped inside the sheath portion concentrically or eccentrically with the sheath portion. In particular, a concentric type and an eccentric type in which the high-melting-point resin is not exposed are preferable in terms of excellent tactile sensation.

In the nonwoven fabric of the present invention, the content of the olefin elastomer in the constituent fibers of the polyolefin thermoplastic resin is at least 3% by weight, and preferably at least 5% by weight from the viewpoint of the effect of improving flexibility. It is preferably less than 30% by weight from the viewpoint of spinnability.

When the constituent fiber of the nonwoven fabric of the present invention is a core-sheath type composite fiber, the core portion contains the olefin-based elastomer in an amount of 3% by weight or more, preferably 5 to 30% by weight, particularly preferably 10 to 30% by weight. It is desirable to use a polyolefin-based thermoplastic resin containing 10% by weight. The weight ratio (S / C) of the core (C) and the sheath (S) in the cross section of the core-sheath conjugate fiber used in the nonwoven fabric of the present invention is 1/9.
９9/1.

Further, when the constituent fibers of the nonwoven fabric of the present invention are side-by-side type conjugate fibers, at least one side of the side-by-side type conjugate fibers contains an olefin-based elastomer in an amount of 3% by weight or more, preferably 5 to 30% by weight. It is desirable to use a polyolefin-based thermoplastic resin containing 10 to 30% by weight, particularly preferably.

The fineness of the fibers constituting the nonwoven fabric of the present invention is as follows:
From the viewpoints of flexibility, appearance, feeling, and the like, 3d or less is preferable, and especially 2.4d or less is preferable.

The nonwoven fabric of the present invention preferably has a small basis weight from the viewpoint of improvement in flexibility, but is usually 15 to 25 g / m ^{2 in} that a nonwoven fabric having sufficient mechanical strength can be obtained.
It is preferable that the weight per unit area is as small as possible.

In the present invention, when a nonwoven fabric made of a single-layer fiber is produced, it can be carried out according to a method such as a spunbond method, a card method, and a melt blown method.

In the case of producing a nonwoven fabric composed of a core-sheath type composite fiber, it can be produced by a method such as a spunbond method, a card method, or a melt blown method. A resin material constituting the core of the sheath-type composite fiber and a resin material constituting the sheath are separately melted by an extruder or the like, and each melt is formed into a desired core-sheath structure and discharged. The core-sheath type composite continuous fiber is discharged from the spinneret having the composite spinning nozzle. The spun composite filament is cooled by a cooling fluid, and tension is further applied to the filament by drawing air to a predetermined fineness. After being collected as it is on a collection belt and deposited to a predetermined thickness. Can be performed according to a confounding method.

Further, in the case of producing a nonwoven fabric composed of side-by-side type conjugate fibers, it can be carried out according to a method such as a spun bond method, a card method and a melt blown method.

Examples of the entanglement method include a method of hot embossing using an embossing roll, a method of fusing by ultrasonic waves, a method of entanglement of fibers using a water jet, hot air through, and needle punching. Various methods such as a method can be appropriately used. Among them, the method of partially performing thermocompression bonding by hot embossing using an embossing roll is preferable in that a nonwoven fabric having particularly excellent friction fastness can be obtained. The ratio of the thermocompression-bonded portion to the nonwoven fabric (embossed area ratio) can be appropriately determined according to the application. Usually, the range of 5 to 40% is excellent in the balance of flexibility, air permeability and friction fastness. Is preferred in that

The nonwoven fabric of the present invention is a nonwoven fabric having a multilayer structure having at least two nonwoven fabric layers containing fibers made of a polyolefin-based thermoplastic resin, wherein at least one nonwoven fabric layer contains the olefin-based elastomer. It may be made of a polyolefin-based thermoplastic resin.
The non-woven fabric having a multilayer structure is preferably one in which each layer is bonded by hot embossing.

The present invention also provides a laminate of the flexible nonwoven fabric and a breathable film. The flexible nonwoven fabric forming the laminate is as described above. In addition, a gas permeable film is a film having a property of not allowing liquid such as moisture to permeate and permeating gas such as water vapor and air. In the present invention, a known film can be used as the breathable film, and is not particularly limited. For example, after forming a film by adding a filler, preferably a filler having a particle size of 0.1 to 7 mm, to a thermoplastic resin, at least 1.5 times or more, preferably 1.5 times or more and 7 times or less. A monolayer or biaxial stretching at a stretching ratio can be exemplified as the breathable film obtained. Among these, a microporous polyolefin film is preferable in terms of excellent bonding properties with the nonwoven fabric of the present invention and flexibility of the film itself.

The polyolefin resin as a material of the microporous polyolefin film is a homopolymer or a copolymer of α-olefin having 2 or more carbon atoms such as ethylene, propylene, 1-butene and the like. Specific examples of the polyolefin resin include high-density polyethylene, medium-density polyethylene, low-pressure low-density polyethylene (linear low-density polyethylene), high-pressure low-density polyethylene, and the like, polypropylene, propylene-ethylene random copolymer, Poly 1-butene and the like. Among these, low-pressure low-density polyethylene and high-pressure low-density polyethylene are preferable, and low-pressure low-density polyethylene is particularly preferable, since the nonwoven fabric of the present invention is less sloppy when touched by hand.

In the present invention, the microporous polyolefin film has a porosity (a ratio of the volume of the pores to the apparent volume of the film) of 30% or more and a moisture permeability of 2000 to 7000 g / m ^2. / 24hr (JIS
The laminated body which is a film of Z0208) is preferable as a material for diapers.

The air-permeable film of the laminate of the present invention contains a weather-resistant stabilizer, a heat-resistant stabilizer, an antistatic agent, an anti-slip agent, an anti-blocking agent, an anti-fogging agent as long as the object of the present invention is not impaired. Additives such as a lubricant, a pigment, a dye, a nucleating agent, a plasticizer, an antioxidant, a hydrochloric acid absorbent, and an antioxidant may be added as necessary.

In the production of the laminate of the present invention, the method for laminating the nonwoven fabric and the breathable film is not particularly limited.
It can be performed by various methods such as extrusion lamination, hot melt lamination, and hot emboss lamination.

[0036]

EXAMPLES Examples and comparative examples of the present invention will be described below.
The present invention will be described more specifically. The spinnability and flexibility in the following Examples and Comparative Examples were measured according to the following methods.

(1) Spinnability During melt spinning, the presence or absence of yarn breakage was investigated, and the spinnability of the nonwoven fabric was evaluated according to the following criteria. ○ No thread break in 5 minutes △ 1-5 thread breaks occurred in 5 minutes × 6 or more thread breaks occurred in 5 minutes

(2) Flexibility In accordance with the C method (Clark method) defined in JIS L1096, the bending and softness of each of the nonwoven fabric in the MD and CD directions are measured, and the total is determined as the flexibility. Was.

Example 1 A propylene homopolymer (M
A mixture of 95 parts by weight (FR: 60 g / 10 minutes) (core resin b) and 5 parts by weight (core resin a) of an olefin-based elastomer (MFR: 18 g / 10 minutes, density: 0.894 g / cm ³ ). , 0.6φ, 1093 holes, spinning at a discharge rate of 1.0 g / min per hole.
A fiber filament having a fineness of ~ 3d was formed and deposited as it was on the collecting surface. Next, the fabric was entangled with a hot embossing roll to obtain a nonwoven fabric having a basis weight of 23 g / m ² . The spinnability and flexibility of the obtained nonwoven fabric were measured or evaluated. Table 1 shows the results.

(Examples 2 and 3) A fiber filament was formed by melt spinning in the same manner as in Example 1 except that the resin material shown in Table 1 was used as the fiber material, and the basis weight was 23 g.
/ M ² of nonwoven fabric. The spinnability and flexibility of the obtained nonwoven fabric were measured or evaluated. Table 1 shows the results.

Example 4 Homopolymer of propylene (M
(FR: 60 g / 10 min) 90 parts by weight and an olefin-based elastomer (MFR: 18 g / 10 min, density: 0.89)
4 g / cm ³ ) A mixture with 10 parts by weight was used as a core material,
Polyethylene (MFR: 30 g / 10 min, density: 0.9
48 g / cm ³ ) as a sheath material, and 0.6φ, 1093
Composite melt spinning is performed by a spinneret with a hole at a discharge rate of 1.0 g / min per hole, and a coaxial core-sheath composite fiber filament having a fineness of about 2 to 3 d and a core-sheath weight composition ratio of 2: 8. Was formed and deposited as it was on the collection surface. Next, the fabric was entangled with a hot embossing roll to produce a nonwoven fabric having a basis weight of 23 g / m ² . The spinnability and flexibility of the obtained nonwoven fabric were measured or evaluated. Table 1 shows the results.

(Example 5) As a core material and a sheath material,
A core-sheath type composite fiber filament was formed by composite melt spinning in the same manner as in Example 2 except that the resin material shown in Table 1 was used, and a nonwoven fabric having a basis weight of 23 g / m ² was produced. The spinnability and flexibility of the obtained nonwoven fabric were measured or evaluated. Table 1 shows the results.

(Comparative Examples 1 to 5) The procedure of Example 1 was repeated except that the resin materials shown in Table 1 were used as the fiber materials.
A nonwoven fabric having a basis weight of 23 g / m ² was produced. The spinnability and flexibility of the obtained nonwoven fabric were measured or evaluated. Table 1 shows the results.

(Comparative Examples 6 and 7) A core-sheath type composite fiber filament was formed by composite melt spinning in the same manner as in Example 2 except that the resin materials shown in Table 1 were used as the core material and the sheath material. A nonwoven fabric having a basis weight of 23 g / m ² was produced.
The spinnability and flexibility of the obtained nonwoven fabric were measured or evaluated. Table 1 shows the results.

[0045]

[Table 1]

Note PE: MFR 30 g / 10 min, density 0.894 g / cm ³ h-PP: homopolypropylene (MFR 60 g / 10 min)
Min) r-PP: propylene / ethylene random copolymer OE: olefin elastomer (MFR: 18 g / 1)
0 minutes, density: 0.894 g / cm ³ )

[0047]

The flexible nonwoven fabric of the present invention is flexible and has an improved surface feel without impairing the moldability and various physical properties.
And it has high friction fastness. Therefore, the flexible nonwoven fabric of the present invention can be used for a wide range of applications such as medical and sanitary materials such as disposable diapers, and industrial materials such as packaging and clothing. Further, the laminate of the present invention is suitable as a material for products such as a back sheet of a disposable diaper by utilizing its features such as flexibility, excellent surface tactile sensation, and excellent friction fastness.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 4F100 AK03A AK03B AK04 AK07 AL09A AL09B AR00C BA02 BA03 BA07 BA10A BA10B BA10C BA12 BA15 DG01A DG01B DG15A DG15B J DG19A DG20A J03BJK13 4L035 AA09 BB31 FF01 FF05 HH10 LA02 MA10 4L041 AA07 AA15 BA02 BA05 BA09 BD03 BD07 BD11 BD20 CA36 CA38 DD01 DD14 DD18 4L047 AA14 AA27 AA28 AB03 BA03 BA04 BA08 CA05 CA06 CA12 CA19 CB01 CB08 CC03 CC04 CC04 CC04 CC04 CC04 CC04 CC04 CC04 CC04

Claims (6)

[Claims] 1. A flexible nonwoven fabric comprising fibers made of a polyolefin thermoplastic resin containing an olefin elastomer. 2. The flexible nonwoven fabric according to claim 1, wherein the fiber made of the polyolefin-based thermoplastic resin contains 3% by weight or more of an olefin-based elastomer. 3. A flexible non-woven fabric comprising a core-sheath composite fiber made of a polyolefin-based thermoplastic resin, wherein the core of the core-sheath composite fiber contains an olefin elastomer. 4. A flexible nonwoven fabric comprising side-by-side conjugate fibers made of a polyolefin-based thermoplastic resin, wherein at least one component of the side-by-side conjugate fibers contains an olefin elastomer. 5. A non-woven fabric layer comprising at least two nonwoven fabric layers containing fibers made of a polyolefin-based thermoplastic resin,
A flexible non-woven fabric, wherein the fibers constituting the two non-woven fabric layers contain an olefin-based elastomer, and each layer is bonded by hot embossing. 6. A laminate of the flexible nonwoven fabric according to claim 1 and a breathable film.