JP5133604B2 - Elastic nonwoven fabric - Google Patents

Description

The present invention relates to a nonwoven fabric composed of thermoplastic elastomer elastic fibers, and relates to a stretchable nonwoven fabric excellent in stretchability and flexibility.

  Conventionally, various nonwoven fabrics have been proposed and used in many fields. Among these, stretchable nonwoven fabrics made of thermoplastic elastomers have excellent stretchability, flexibility and breathability, and their use has been expanding in recent years. For example, it is used in a wide range of fields such as sanitary materials such as disposable paper diapers and sanitary napkins, medical materials such as emergency bandages, haptic base fabrics, supporters and bandages, as well as gloves, inner caps, and sports clothing materials.

These nonwoven fabrics are required to have stretchability, flexibility, recoverability, etc., but those that satisfy these performances are stretchable nonwoven fabrics of thermoplastic elastomers such as polyurethane, polyester elastomer, polyamide elastomer, polyolefin elastomer, etc. Has been proposed. However, the polyurethane, polyester elastomer, and polyamide elastomer of the above materials are hygroscopic due to the properties of the resin, so a resin drying process in the nonwoven fabric manufacturing process is required. Problems such as the influence on the nonwoven fabric product and the troublesome management of the moisture content in the resin can be mentioned. Also, depending on the resin, there are problems in heat resistance, light resistance, chemical resistance, hydrolysis resistance, recyclability, and the like. There has been a demand for stretchable nonwoven fabrics using raw materials that do not have these problems, and as a method for solving the above problems, the use of polyolefin elastomers reduces the burden of water content management, and heat It has been studied to avoid a decrease in productivity due to decomposition.

In particular, polypropylene is widely used in the fiber field because it is inexpensive and has excellent mechanical properties, moisture resistance and heat resistance. In order to obtain fibers that are more supple and excellent in texture, a method using syndiotactic polypropylene, which is a relatively soft polypropylene, has been proposed. Japanese Patent Application Laid-Open No. 8-176369 discloses a fiber obtained by blending syndiotactic polypropylene with isotactic polypropylene for the purpose of improving moldability, but is not sufficient in flexibility and flexible. It is not always satisfactory in terms of texture and stretchability.

Japanese Patent Laid-Open No. 5-171556 proposes an elastic nonwoven fabric using an ethylene / α-olefin copolymer. However, this elastic nonwoven fabric has a problem of low elastic performance.

JP-A-8-013237 proposes a hydrogenated block copolymer comprising a polybutadiene block having a vinyl bond content of 30% or less and a copolymer block comprising isoprene / butadiene and an elastic fiber containing an olefin polymer. However, since this elastic fiber contains isoprene, it is sticky, and the product obtained has a problem of poor antiblocking properties.

JP-A-9-105056 discloses an ethylene / α-olefin copolymer and styrene /
A melt blown nonwoven fabric made of a composition containing an ethylene / butylene / styrene block copolymer has been proposed. However, since the resin is processed at a relatively high temperature by the melt-blowing method, the styrene block is likely to be broken, the stretchability of the resulting nonwoven fabric is reduced, and a nonwoven fabric having satisfactory anti-blocking properties cannot be obtained.

In JP-A-11-117165, a composition containing low density polyethylene, styrene / ethylene / butylene / styrene block copolymer and polypropylene is made into a nonwoven fabric by a melt blow method in order to improve antiblocking properties. Proposed. However, the inclusion of polypropylene does not have satisfactory elasticity because the elastic performance is hindered.

Japanese Patent Laid-Open No. 11-12908 proposes an elastic nonwoven fabric containing a hydrogenated diene polymer and a crystalline low molecular weight polyolefin having a number average molecular weight of 20000 or less. In addition, there are problems that the elongation at break is less than 200%, it is very brittle, the stretchability is low, and the stress during elongation is extremely high.

JP-A-8-176369 JP-A-5-171556 JP-A-8-013237 JP-A-9-105056 JP-A-11-117165 Japanese Patent Laid-Open No. 11-12908

An object of the present invention is to provide a stretchable nonwoven fabric that eliminates these drawbacks, has excellent stretchability and flexibility, has sufficient strength, and has improved non-stickiness (anti-blocking property) of the nonwoven fabric. There is.

As a result of intensive studies to solve the above problems, the present inventors have melted a mixture of an elastomeric polypropylene, a thermoplastic elastomer (A) composed of a propylene / ethylene copolymer and a polypropylene resin (B). The inventors have found that by spinning, a stretchable nonwoven fabric having excellent stretchability and flexibility, sufficient strength and improved non-stickiness of the nonwoven fabric can be obtained, and the present invention has been completed. The present invention is constituted as follows. (1) A stretchable nonwoven fabric comprising a mixture of at least one thermoplastic elastomer component (A) selected from elastomeric polypropylene and propylene / ethylene copolymer and a homopolypropylene resin (B), wherein the thermoplastic elastomer component mixing weight ratio of (a) and the homo polypropylene resin (B) [(a) / (B)] is 50 / 50-95 / 5 der Ri, MFR value of the thermoplastic elastomer component (a) is 50 to 400 ( g / 10 min), the MFR value of the polypropylene resin (B) is 25 to 200 (g / 10 min), and the ratio of these MFR values [MFR (A) / MFR (B)] is 1 to 10. Ah is, the breaking strength per unit basis weight of the stretchable nonwoven fabric (1 g / ^m per ²⁾ 3.5 N / cm or higher, elongation at break of 300% or more, per unit basis weight tear strength ( 1 g / ^m per ²⁾ 1.5 N / cm or more, 50% elongation recovery of 80% or more elastic nonwoven fabric. ( 2 ) A stretchable nonwoven fabric in which the stretchable nonwoven fabric is made by a melt blow method.

According to the present invention, it is possible to obtain a stretchable nonwoven fabric having excellent stretchability and flexibility, sufficient strength, and improved adhesiveness of the nonwoven fabric.

Hereinafter, the present invention will be described in detail. First, the resin constituting the nonwoven fabric of the present invention will be described. The thermoplastic resin used for the stretchable nonwoven fabric is at least one thermoplastic elastomer component (A) selected from elastomeric polypropylene and propylene / ethylene copolymer.
And a mixture of homopolypropylene resin (B).

The elastomeric polypropylene used in the present invention is a polypropylene having a stereo block structure in which a polymer chain is composed of crystalline isotactic polypropylene or syndiotactic polypropylene and amorphous atactic polypropylene. It has a structure having isotactic polypropylene or syndiotactic polypropylene in the hard segment and atactic polypropylene in the soft segment.

Elastomeric polypropylene includes homopolymers and copolymers, which in addition to propylene units, other olefin units other than propylene units in the molecule,
For example, those containing ethylene, butylene, pentene or hexene units. These have a substantially stereoregular block sequence in the chain structure and consist of, for example, isotactic polypropylene and atactic polypropylene ordered blocks selectively arranged in the polymer chain. It is produced by polymerization or copolymerization by propylene or a catalytic reaction of the propylene and other α-olefin.

The MFR value of the resin is preferably 50 to 400 (g / 10 minutes). Within this range, a nonwoven fabric having excellent productivity and good stretchability, strength, texture and the like can be obtained, which is preferable.

  The propylene / ethylene copolymer as the thermoplastic elastomer component used in the present invention is a propylene / ethylene random copolymer or a propylene / ethylene block copolymer, or a propylene / ethylene random copolymer and a propylene / ethylene block copolymer. It is a mixture with coalescence. The propylene / ethylene block copolymer is not a blend of polypropylene, polyethylene, and poly (ethylene-co-propylene), but has a polypropylene segment, a polyethylene segment, and a poly (ethylene-co-propylene) segment. It is chemically bonded (covalent bond). The MFR value of the propylene / ethylene copolymer used in the present invention is preferably 50 to 400 (g / 10 min). Within this range, a nonwoven fabric having excellent productivity and good stretchability, strength, texture and the like can be obtained, which is preferable.

The homopolypropylene resin (B) of the present invention is a polypropylene homopolymer. The MFR value of the resin is preferably 25 to 200 (g / 10 minutes), more preferably 25 to 100 (g / 10 minutes). Within this range, it is preferable because the nonwoven fabric has excellent productivity and anti-sticking performance of the nonwoven fabric.

The mixing ratio of the resin composition constituting the stretchable nonwoven fabric of the present invention is a mixture of at least one thermoplastic elastomer component (A) and homopolypropylene resin (B) selected from elastomeric polypropylene and propylene / ethylene copolymer. The weight ratio [(A) / (B)] is 5
It needs to be 0/50 to 95/5, and preferably 60/40 to 90/10. The thermoplastic elastomer component (A) contributes to the stretchability and recoverability of the nonwoven fabric, and the homopolypropylene resin (B) contributes to imparting the strength, elongation stress and anti-sticking property of the nonwoven fabric. In particular, when the content of the homopolypropylene resin (B) in the nonwoven fabric increases, the strength of the elastic fibers constituting the nonwoven fabric is improved, but the stretchability and recoverability are hindered, and the adhesiveness between the fibers decreases, so the nonwoven fabric. The web formation deteriorates. On the other hand, when the content of the homopolypropylene resin (B) in the nonwoven fabric decreases, the strength of the nonwoven fabric becomes insufficient, causing the nonwoven fabric to stick, causing problems in handling.

Further, the ratio of the MFR values of the respective resins when using a mixture of at least one thermoplastic elastomer component (A) selected from elastomeric polypropylene and propylene / ethylene copolymer and homopolypropylene resin (B) [ MFR (A) / MFR (B)] is 1
10 is preferable. Within this range, the compatibility of the respective resins at the time of heat melting is good and the operability of nonwoven fabric production is excellent, which is preferable.

The composition comprising the component (A) and the component (B) used in the production of the stretchable nonwoven fabric of the present invention includes hindered phenols, various amine antioxidants, benzotriazoles, hindered amines as necessary. UV absorbers such as amide wax, montanic acid wax, etc., hydrolysis inhibitors such as various carbodiimide compounds, matting agents such as titanium oxide, various pigments such as bengara, colorants, yellowing prevention agents, etc. A polymer additive, an antifungal agent, an antibacterial agent, and other various improving agents can be added and blended as necessary.

Examples of the method for producing the stretchable nonwoven fabric of the present invention include known production methods such as the spunbond spinning method and the melt blow spinning method. The melt blow spinning method is preferred from the viewpoint of the stretchability and flexibility of the resulting nonwoven fabric.

A general method of melt blow spinning will be described as follows. The thermoplastic resin is melted with an extruder and the molten polymer is measured with a gear pump, and then discharged from spinning nozzle holes arranged in a row. A high-temperature heated gas is jetted at high speed from slits arranged on both sides of the nozzle hole, and the polymer extruded from the nozzle hole is thinned and cooled by the high-speed gas flow to form a continuous filament. The thinned filaments are separated from the gas stream on the moving conveyor net collection device and are laminated onto the net without being substantially focused. The contact points of the laminated filaments are joined by fusion in a state of being laminated by the heat of the self. You may make it join by heating and pressurizing using a roller etc. before or after cooling solidification after lamination on a collection device. In order to strengthen the bonding at the contact points between the filaments, the distance from the spinning nozzle to the position where the filaments are stacked on the collecting device should not be too long, and should be set to 10 to 100 cm. A gas flow guiding passage may be provided between the nozzle and the collecting device, but it may be omitted.

  In the stretchable nonwoven fabric of the present invention, it is preferable that filaments made of a thermoplastic resin are spread and laminated without substantially converging over the fiber longitudinal direction. If the single yarn is fused in a bundled state without being opened, the uniformity of the nonwoven fabric is lowered and the flexibility is significantly impaired.

The stretchable nonwoven fabric of the present invention, the fiber diameter is 5 to 30 [mu] m, basis weight 20~1200g / ^{m 2,} the breaking strength (1 g / ^m per ²⁾ 3.5 N / cm or higher, elongation at break of 300% or more, the unit Tear strength per unit weight (per 1 g / m ² ) is 1.5 N / cm or more, 50% elongation recovery rate is 80
% Or more is preferable. Within this range, the productivity of the nonwoven fabric is excellent, and the resulting nonwoven fabric has good strength, stretchability, and texture in practical use. Another feature is that it has excellent air permeability, and the air permeability is preferably 5 to 200 cc / cm ² / s.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to this Example. Evaluation of the nonwoven fabric in description of an Example measured by the method shown below.

MFR measurement of resin: Measurement of melt flow rate (MFR) Measured at 230 ° C. and a load of 21.2 N in accordance with JIS K 7210.

Average fiber diameter of nonwoven fabric: Using a scanning electron microscope (SEM), a 500-fold magnified photograph of the nonwoven fabric surface was taken, the diameter of 50 fibers was measured, and the average value was taken as the average fiber diameter.

Non-woven fabric weight and thickness: Measured in accordance with JIS L1906 “General Long Fiber Nonwoven Fabric Test Method”. For the basis weight, a 100 × 100 mm test piece was sampled, and the weight was measured and converted per 1 m ² . The thickness was measured using a dial thickness gauge (manufactured by Ozaki Seisakusho).

Breaking strength and breaking elongation of nonwoven fabric: Measured in accordance with JIS L1906 “General Long Fiber Nonwoven Fabric Test Method”. A test piece having a width of 25 mm and a length of 200 mm was collected and a tensile tester (
The test piece was fixed with the gap between chucks set to 100 mm. The test piece was stretched at a tensile speed of 300 mm / min, and the strength and elongation per 1 cm width and 1 g / m ² (unit weight) at the time of breaking were measured.

Air permeability of nonwoven fabric: Measured according to the fragile method of JIS L1906 “Testing method for general long-fiber nonwoven fabric”. A test piece of about 200 × 200 mm is collected and a breathability tester (TE
XTEST).

Stretch recovery rate of nonwoven fabric: Measured according to JIS L1096 “General Textile Test Method”. However, evaluation in the present invention is a recovery rate at an elongation of 50%, a width of 25 mm, and a length of 200 m.
m test pieces were collected and a tensile tester (Orientec Co., Ltd.) was used, and the distance between chucks was 100 m.
The test piece was fixed to m. After extending to 50% at a pulling speed of 300 mm / min, the crosshead was returned to its original position at the same speed as when stretched, and the stress applied to the nonwoven fabric was set to zero.
Stretch again to 50% at the same speed, and the stretch length of the nonwoven fabric when the stress load starts again is L
mm. The elongation recovery rate was determined according to the following formula.
Elongation recovery rate (%) = ((50−L) / 50) × 100
Tear strength of non-woven fabric: Measured according to JIS L1906 “General long-fiber non-woven fabric test method”.

[Comparative Example 1]
A propylene / ethylene copolymer (VM2120 manufactured by ExxonMobil) was melted with an extruder at 215 ° C. and weighed with a gear pump, and was discharged from a melt blow nozzle in which holes with a diameter of 0.5 mm were arranged in a row at a pitch of 2 mm. A filament is formed by extruding the polymer under a discharge condition of 0.3 g / min per hole of the nozzle and thinning and solidifying with heated air (236 ° C.) blown from both sides of the nozzle, and the filament is separated from the nozzle by 20 cm. Sprayed on the moving conveyor net at the position. A nonwoven fabric having a basis weight of 75.2 g / m ² and an average fiber diameter of 20 μm was obtained. The spinning temperature at this time was 218 ° C. Adhesion occurred after the nonwoven fabric was taken off.

  Tables 1 and 2 show the spinning status of the nonwoven fabric and the measurement results of the physical properties of the nonwoven fabric.

[Example 1]
Propylene / ethylene copolymer of Comparative Example 1 (VM2120, MFR manufactured by ExxonMobil)
= 70) 5 polypropylene resin (Ydemitsu Petrochemical Y-6005GM, MFR = 60)
% Was melt-kneaded with an extruder at 220 ° C., and the following was performed in the same manner as in Comparative Example 1 to produce a nonwoven fabric. A nonwoven fabric having a basis weight of 75.0 g / m ² and an average fiber diameter of 22 μm was obtained. Spinning temperature is 220
At ℃, the spinning situation was good.

[Example 2]
Example 1 Propylene / Ethylene Copolymer (VM2120, MFR manufactured by ExxonMobil)
= 70) polypropylene resin (Ydemitsu Petrochemical Y-6005GM, MFR = 60) 1
After adding 0%, the mixture was melt-kneaded with an extruder at 225 ° C., and a nonwoven fabric was produced in the same manner as in Comparative Example 1. A nonwoven fabric having a basis weight of 74.7 g / m ² and an average fiber diameter of 20 μm was obtained. Spinning temperature is 22
At 3 ° C, the spinning situation was good.

[Example 3]
Example 1 Propylene / Ethylene Copolymer (VM2120, MFR manufactured by ExxonMobil)
= 70) polypropylene resin (Ydemitsu Petrochemical Y-6005GM, MFR = 60) 2
After adding 0%, it was melt-kneaded with an extruder at 235 ° C. The following was performed in the same manner as in Comparative Example 1 to produce a nonwoven fabric. A nonwoven fabric having a basis weight of 75.2 g / m ² and an average fiber diameter of 21 μm was obtained. Spinning temperature is 23
At 2 ° C, the spinning situation was good.

[Example 4]
Example 1 Propylene / Ethylene Copolymer (VM2120, MFR manufactured by ExxonMobil)
= 70) 5 polypropylene resin (Ydemitsu Petrochemical Y-6005GM, MFR = 60)
After adding 0%, the mixture was melt-kneaded with an extruder at 245 ° C. The following was performed in the same manner as in Comparative Example 1 to prepare a nonwoven fabric. A nonwoven fabric having a basis weight of 75.4 g / m ² and an average fiber diameter of 22 μm was obtained. Spinning temperature is 24
At 2 ° C, the spinning situation was good.

[Comparative Example 2]
Example 1 Propylene / Ethylene Copolymer (VM2120, MFR manufactured by ExxonMobil)
= 70) Polypropylene resin (Ydemitsu Petrochemical Y-6005GM, MFR = 60) 6
7% was added and melt-kneaded with an extruder at 255 ° C. The following was performed in the same manner as in Comparative Example 1 to prepare a nonwoven fabric. A nonwoven fabric having a basis weight of 75.1 g / m ² and an average fiber diameter of 20 μm was obtained. Spinning temperature is 25
At 2 ° C., the state of polymer discharge from the nozzle was good during spinning, but the nonwoven fabric obtained by the occurrence of yarn breakage was not uniform.

[ Comparative Example 3 ]
20% of a polypropylene resin (Y-2000G, MFR = 20 manufactured by Idemitsu Petrochemical Co., Ltd.) was added to the propylene / ethylene copolymer (VM2120 manufactured by ExxonMobil, MFR = 70) of Example 1 and melt-kneaded with an extruder at 235 ° C. And the following produced the nonwoven fabric like the comparative example 1. A nonwoven fabric having a basis weight of 75.1 g / m ² and an average fiber diameter of 22 μm was obtained. The spinning temperature was 233 ° C., the polymer discharge state from the nozzle was not good during spinning, shots and yarn breaks occurred frequently, and the obtained nonwoven fabric was not uniform.

[Comparative Example 4 ]
In Comparative Example 1, a propylene / ethylene copolymer (VM2330 manufactured by ExxonMobil, MFR = 300) was used for melt kneading with an extruder at 210 ° C., and the following was performed in the same manner as Comparative Example 1 to produce a nonwoven fabric. A nonwoven fabric having a basis weight of 75.4 g / m ² and an average fiber diameter of 22 μm was obtained. The spinning temperature was 203 ° C. and the spinning situation was good. However, agglutination occurred after the nonwoven fabric was scraped.

[Example 6]
Propylene / ethylene copolymer of Comparative Example 2 (VM2330, MFR manufactured by ExxonMobil)
= 300) polypropylene resin (Ydemitsu Petrochemical Y-6005G, MFR = 60) 1
After adding 0%, the mixture was melt-kneaded with an extruder at 210 ° C., and a nonwoven fabric was produced in the same manner as in Comparative Example 1. A nonwoven fabric having a basis weight of 75.4 g / m ² and an average fiber diameter of 20 μm was obtained. Spinning temperature is 20
At 7 ° C, the spinning situation was good.

[Example 7]
Propylene / ethylene copolymer of Comparative Example 2 (VM2330, MFR manufactured by ExxonMobil)
= 300) was added 20% polypropylene resin (Idemitsu Petrochemical Y-6005GM, MFR = 60) and melt-kneaded with an extruder at 210 ° C. The following was performed in the same manner as in Comparative Example 1 to produce a nonwoven fabric. A nonwoven fabric having a basis weight of 76.0 g / m ² and an average fiber diameter of 22 μm was obtained. Spinning temperature is 2
At 10 ° C, the spinning situation was good.

INDUSTRIAL APPLICABILITY The present invention can provide a stretchable nonwoven fabric having excellent stretchability and flexibility, sufficient strength and improved non-stickiness of the nonwoven fabric, and as a fiber product, for example, a disposable diaper member. , Stretchable members for sanitary products, stretchable tapes, adhesive bandages, stretchable members for clothes, hats, masks, gloves, supporters, stretchable bandages, poultice base fabrics, vibration absorbers, finger sack, filters, separators, etc. Can be suitably used.

Claims (3)

A stretchable nonwoven fabric comprising a mixture of at least one thermoplastic elastomer component (A) selected from elastomeric polypropylene and propylene / ethylene copolymer and a homopolypropylene resin (B), wherein the thermoplastic elastomer component (A) The mixing weight ratio [(A) / (B)] of the homopolypropylene resin (B) is 50/50 to 95/5, and the MFR value of the thermoplastic elastomer component (A) is 50 to 400 (g / 10 min). The MFR value of the polypropylene resin (B) is 25 to 200 (g / 10 min), the ratio of these MFR values [MFR (A) / MFR (B)] is 1 to 10, and the expansion and contraction The breaking strength per unit weight of the porous nonwoven fabric (per 1 g / m ² ) is 3.5 N / cm or more, the breaking elongation is 300% or more, the tear strength per unit weight (1 g / m ² ). m per ²⁾ is 1.5 N / cm or more, 50% stretchable nonwoven fabric elongation recovery rate is characterized der Rukoto 80% or more. The stretchable nonwoven fabric according to claim 1, wherein the stretchable nonwoven fabric is made by a melt blow method. The stretchable nonwoven fabric according to claim 1 or 2, wherein the mixing weight ratio [(A) / (B)] of the thermoplastic elastomer component (A) and the homopolypropylene resin (B) is 60/40 to 90/10.