JPH11131351A - Continuous filament nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain continuous filament nonwoven fabric that has excellent mechanical properties, dimensional stability, light transmission properties, air permeability and quality, and is made of filaments of thick fineness with a low unit weight and particularly suitable for agricultural purpose. SOLUTION: This nonwoven fabric is made of a sheath-core type conjugated fibers that has a fiber diameter of >=3.5 μm and the sheath part 1 is made of an olefin resin and the core part 2 is made of an ester resin mainly comprising ethylene terephthalate having a melting point more than 30 deg.C higher than the melting point of the olefin resin. In addition, the ester resin of the core part has a hollow part 3 with a hollowness percentage of 10-60%. Thus, the constitution fibers are mutually integrated by hot melting of the olefin resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-fiber non-woven fabric, and more particularly to a mechanical non-woven fabric having excellent mechanical properties, dimensional stability, light transmittance, water permeability and light weight. The present invention relates to a long-fiber nonwoven fabric suitable for a nonwoven fabric for agricultural use, a nonwoven fabric for drainage filtration, and the like, used for bags and drainage filters.

[0002]

2. Description of the Related Art A long-fiber nonwoven fabric formed of a thermoplastic material is a material having excellent mechanical properties, dimensional stability, translucency, and water permeability. It is widely used as a sheet for various agricultural uses such as solid cultivation for open-field cultivation, and as a drain bag for kitchen use.

[0003] The long-fiber non-woven fabric used for this kind of application, for example, for solid application, is mainly a non-woven fabric having a relatively large fineness and a small basis weight in order to prevent crops from growing too long. Similarly, long-fiber nonwoven fabrics used for kitchen draining bags are mainly nonwoven fabrics having a relatively large fineness and a small basis weight in order to obtain excellent drainage properties.

For example, Japanese Utility Model Laid-Open Publication No. 4-8769 discloses that the fibers are made of hydrophobic fibers of 6 denier or more and have a basis weight of 10%.
Solid agricultural coverings of ３０30 g / m ² are disclosed.

[0005]

However, even if it is attempted to obtain a large fineness using a conventional nonwoven fabric manufacturing method, the fineness disclosed in the above publication is almost at its limit, and further a large fineness yarn is to be obtained. Then, there are many problems as described below. That is, (1) since the cooling and solidification of the spun yarn is slow,
That a special cooling device is required, (2) that the cooling and solidification of the spun yarn is slow, and that the distance from the spinneret to the yarn suction device installed thereunder needs to be increased;
(3) In order to cool and solidify the spun yarn, not only impairs the uniformity of the yarn due to providing severe cooling conditions, but in extreme cases, a difference in birefringence occurs in the fiber diameter direction. Spiral crimps are developed and the quality of the long-fiber nonwoven fabric as a final product is significantly impaired.

[0006] The present invention is to solve such problems, and is a long-fiber nonwoven fabric having a large fineness, and is excellent in mechanical properties, dimensional stability, light transmittance, water permeability and light weight,
In particular, it is an object of the present invention to obtain a long-fiber nonwoven fabric having further improved characteristics of a solid nonwoven fabric for agricultural use, a nonwoven fabric for draining filtration, and a nonwoven fabric for civil engineering.

[0007] The present invention also provides mechanical properties, dimensional stability,
It is an object of the present invention to obtain a long-fiber nonwoven fabric having excellent translucency, breathability, light weight, and quality, and having a large fineness and a low basis weight, particularly suitable for agricultural use.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, in the present invention, the fiber diameter is 35 μm or more, and in the cross section of the fiber, the olefin-based resin forms a sheath, and the main component is ethylene terephthalate having a melting point higher than the melting point of the olefin-based resin by 30 ° C. or more. The ester-based resin to form a core portion, and the ester-based resin of the core portion is formed of a long fiber of a two-component core-sheath hollow structure having a hollow portion and having a hollow ratio of 10 to 60%, The present invention provides a long-fiber nonwoven fabric characterized in that the constituent fibers are integrated by thermal fusion of an olefin resin.

With such a configuration, a long-fiber nonwoven fabric is constituted by a large-filament yarn having a hollow cross section of a two-component core-sheath hollow composite of an olefin resin and an ester resin.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the cross-sectional shape of a fiber constituting a nonwoven fabric is mainly composed of ethylene terephthalate whose olefin resin forms a sheath and whose melting point is 30 ° C. or higher than the melting point of the olefin resin. It is necessary that the ester resin to be formed forms a core portion and the polyester resin of the core portion has a two-component core-sheath hollow shape having a hollow portion.

By adopting such a two-component core-sheath structure of an olefin resin and an ester resin, the olefin resin in the sheath portion is thermally damaged at a partial thermocompression bonding portion for forming a nonwoven fabric. However, since the melting point of the ester-based resin in the core is higher than the melting point of the olefin-based resin in the sheath by 30 ° C. or more, the ester-based resin is not significantly damaged. Conversely, the difference between the two melting points is 30
When the temperature is lower than ° C, the ester-based resin in the core is thermally damaged, and the mechanical properties and flexibility of the obtained long-fiber nonwoven fabric are inferior.

Examples of olefin resins which can be used in the present invention include aliphatic α-monoolefins having 2 to 16 carbon atoms, such as ethylene, propylene, 1-butene,
1-pentene, 3-methyl 1-butene, 1-hexene,
Examples include 1-octene, 1-dodecene, and 1-octadecene homopolyolefins or copolymerized polyolefins.
Aliphatic α-monoolefins include other olefins and
Or with small amounts (up to about 10% by weight of polymer weight) of other ethylenically unsaturated monomers, for example similar ethylenically unsaturated monomers such as butadiene, isoprene, pentadiene-1,3, styrene, α-methylstyrene. It may be polymerized. Particularly in the case of polyethylene, those copolymerized with propylene, butene-1, hexene-1, octene-1 or a similar higher α-olefin up to about 10% by weight of the polymer are preferred.

Examples of the ester resins which can be used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid and adipic acid, sebacic acid and the like as acid components. A homopolyester or a synthetic polyester synthesized from an aliphatic dicarboxylic acid or an ester thereof and a diol compound such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, or cyclohexane-1,4-dimethanol as an alcohol component. There is a copolyester, the above polyester paraoxybenzoic acid, 5-sodium sulfoisophthalic acid,
Polyalkylene glycol, pentaerythritol, bisphenol A and the like may be added or copolymerized.

The olefin resin and the ester resin include a matting agent, a pigment, a flame retardant, a deodorant, an antistatic agent, an antioxidant, as long as the object of the present invention is not impaired.
Arbitrary additives such as an ultraviolet absorber and an antibacterial agent may be added.

The cross-section of the constituent fibers of the nonwoven fabric of the present invention is such that the sheath is formed of an olefin-based resin as a low-melting material, and the core is formed of an ester-based resin as a high-melting material, as described above. , A two-component core-sheath hollow cross section having a hollow portion in the core portion.

By using fibers having such a cross-sectional structure, the cooling speed of the spun yarn can be increased even with a large fineness, and a conventionally known device can be used without using a special spinning device and cooling device. Thus, it is possible to obtain a nonwoven fabric which is excellent in mechanical performance and quality and is composed of fibers of large fineness. In addition, when the two-component core-sheath hollow fiber constituting the nonwoven fabric of the present invention has the same fiber diameter as the round cross section, the weight can be reduced. In the case of the same fineness, the two-component core-sheath hollow fiber of the present invention naturally has a larger fiber diameter than that of the round cross-section.

The hollowness of the hollow fibers must be in the range of 10 to 60%. This hollow ratio represents the ratio of the area of the entire fiber and the area of the hollow portion in the fiber cross section,
It is determined by the following formula: hollow ratio = hollow portion diameter / fiber outer diameter × 100 (%). If the hollow ratio is less than 10%, not only the cooling rate of the spun yarn cannot be sufficiently increased, but also the diameter of the fiber becomes insufficient, and the weight of the long-fiber nonwoven fabric is reduced and the nonwoven fabric for agricultural use is reduced. When applied, it has little effect on improving the light transmittance and water permeability. Conversely, the hollow ratio is 60
%, The effect of cooling the spun yarn and the effect of reducing the weight of the long-fiber non-woven fabric and improving the light transmittance and water permeability are sufficient, but the fibrillation of the constituent fibers is liable to occur and the durability is reduced. In addition to causing trouble, the hollowness is too high in the manufacturing process, leading to a serious trouble that the spinning property is reduced or the membrane forming the hollow portion of the fiber is broken (so-called puncture). . For this reason,
A more preferable hollow ratio is 20 to 50%. The hollow ratio is
It can be controlled by the pore size of the spinneret, the viscosity of the two-component resin, and the cooling conditions of the spun yarn. In general, it is easier to increase the hollow ratio of thick fine yarn compared to fine fine yarn.

It is necessary that the fiber diameter is 35 μm or more. When the fiber diameter is less than 35 μm, for example, when applied to an agricultural sheet, there is a problem that the heat retention is excellent, but the air permeability and the transmittance of sunlight, which is indispensable for the growth of plants, are inferior and the yield is reduced. I do. In addition, when applied to a nonwoven fabric for drainage filtration, the gap between the fibers becomes small, the water permeability decreases, and the drainage property deteriorates.
Further, when applied to a nonwoven fabric for civil engineering, weight reduction is inferior. For this reason, the preferred fiber diameter is 37-4.
2 μm.

That is, in the long-fiber nonwoven fabric, a space where no fiber is present is formed between the constituent fibers, and the size of this space is greatly affected by the fineness of the constituent fibers. That is, the greater the fineness of the constituent fibers, the larger this space becomes, and the light transmittance and water permeability of the nonwoven fabric are improved. This property is greatly affected by the fineness of the fiber, especially when the basis weight of the nonwoven fabric is low.

In the nonwoven fabric of the present invention, constituent fibers must be partially heat-sealed and integrated at a processing temperature lower than the melting point of the olefin resin in the sheath. Partial heat fusion refers to a long fiber web between a metal roll or embossing roll, which is heated to a temperature below the melting point of the olefin resin and has an engraved pattern imprinted on the surface, and a heated, smooth surfaced metal roll. Through which the fibers in contact with the projecting portions of the engraved pattern are thermally fused together. Thermal fusion can also be performed using an ultrasonic fusion machine.

This heat fusion will be described in more detail. The heat-sealed portion is formed in a specific region on the surface of the nonwoven fabric. In other words, each heat-sealed region does not necessarily have to be circular, but has an area of 0.1 to 1.0 mm ^{2 and} an existing density, that is, a compression point density of 4 to 50 points /
cm ² , preferably 10 to 40 points / cm ² . If the compression point density is less than 4 points / cm ² , the long-fiber nonwoven fabric is excellent in light transmittance and water permeability, but does not improve mechanical properties and shape retention, and conversely, the compression point density is 50 points / cm ^2. c
If it exceeds m ² , the long-fiber nonwoven fabric is excellent in mechanical properties and shape retention, but is not preferable because it is inferior in light transmittance and water permeability even though it is composed of a yarn of large fineness. The ratio of the area of the entire press contact area to the entire surface area of the long fiber nonwoven fabric, that is, the press contact area ratio is preferably 5 to 30%,
-20% is more preferable. If the pressed area ratio is less than 5%, the mechanical properties and dimensional stability of the long-fiber nonwoven fabric will be inferior. Conversely, if it exceeds 30%, the flexibility of the long-fiber nonwoven fabric and the air permeability of the nonwoven fabric for agricultural use will be reduced.

The temperature for heat fusion needs to be lower than the melting point of the olefin resin. If the processing temperature exceeds the melting point of the olefin-based resin, not only will the resin stick to the heat-sealing machine using the above-mentioned hot embossing roll, etc., significantly impairing the operability, but also the texture of the long-fiber nonwoven fabric becomes hard and the soft nonwoven fabric Cannot be obtained.

The basis weight of the long-fiber nonwoven fabric may be appropriately selected depending on the application.
The basis weight must be 5 to 30 g / m ² . If the basis weight is less than 5 g / m ² , only an agricultural nonwoven fabric having poor uniformity of the basis weight distribution and poor mechanical properties can be obtained. Conversely, when the basis weight exceeds 30 g / m ² , the air permeability and the light transmission are poor, and as a result, the crop yield is reduced. For this reason, a more suitable basis weight is 8 to 25 g / m ² . On the other hand, a high basis weight is suitable for civil engineering.

The agricultural nonwoven fabric of the present invention preferably has an air-permeability, which will be described later, of 1 m / sec or more. If the notification blocking property is less than 1 m / sec, a damaging disease is likely to occur and a satisfactory crop cannot be obtained.

The agricultural nonwoven fabric of the present invention preferably has a translucency of 500 lux or more as described later. If the translucency is less than 500 lux, there is a tendency that a desired crop cannot be obtained without prolongation.

The long-fiber non-woven fabric composed of the two-component core-sheath hollow long fibers of the present invention is generally produced by the following method. That is, spinning is performed by a conventionally known melt composite spinning machine, and the spun yarn is cooled by a blowing wind using a conventionally known cooling device such as a horizontal spraying or an annular spraying. Using it, it is drawn and thinned to the target fineness and taken up. A traction speed of 3000 m / min or more, especially 4000 m / min or more, is suitable for improving the dimensional stability of the nonwoven fabric. The bicomponent core-sheath hollow filaments discharged from air soccer are generally passed through a corona discharge zone or a frictional collision zone in a high-voltage electric field, charged and spread, and then used as a screen conveyor. The fibers can be spread and accumulated on a moving deposition device to form a long fiber web. Next, the target nonwoven fabric is obtained by partially thermally fusing the long fiber web at a processing temperature equal to or lower than the melting point of the olefin resin using a thermocompression bonding apparatus.

[0027]

Next, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

The characteristic values shown in the examples were measured by the following methods.

Melt index of polyethylene Measured according to the method described in ASTM D-1238 (E).

Melt flow rate of polypropylene Measured according to the method described in ASTM D-1238 (L).

Intrinsic viscosity of polyester Measured at 20 ° C. in a mixed solution of phenol and tetrachloroethane in a ratio of 1: 1.

Fiber diameter Bicomponent core-sheath hollow long fibers in a web state (50 fibers)
The cross-section of the fiber is observed with a microscope to measure the fiber outer diameter,
The average value was defined as the fiber diameter.

Hollowness ratio Bicomponent core-sheath hollow long fibers in a web state (50 fibers)
The fiber outer diameter and the hollow part diameter were measured by observing the cross section of the fiber with a microscope, and the hollow ratio = hollow part diameter / fiber outer diameter x 100 (%) was calculated for each fiber, and the average value was calculated as hollow. Rate.

Fineness 1 Bicomponent core-sheath hollow long fiber in a web state (50 fibers)
Was photographed, and for each fiber, the fiber outer diameter, the thickness of the polyolefin layer and the polyester layer, and the diameter of the hollow portion were measured, and density correction was further performed.

Fineness 2 (apparent fineness) Bicomponent core-sheath hollow long fiber in the web state (50 fibers)
Take a cross section of the photograph, measure the outer diameter of each fiber, assuming that there is no hollow portion, using the average density of the polyolefin resin and polyester resin, make a density correction, the average value of fineness 2 and did.

Tensile strength of non-woven fabric According to the strip method described in JIS L-1096, 10 pieces of a sample having a width of 5 cm and a length of 10 cm are prepared, and the maximum tensile strength is measured for each sample at a tensile speed of 10 cm / min. And the average value was defined as tensile strength (kg / 5 cm width).

Air permeability of non-woven fabric Five samples of 30 cm square were prepared and measured using a wind speed measuring instrument (Model 6621, manufactured by Nippon Kanomax Co., Ltd.) as a wind generator and measuring instrument at a wind speed of 10 m / sec. That is,
The sample was placed vertically at a position of a wind speed of 7 m / sec, the wind speed passing through the sample was measured for each sample at a position of 1 cm immediately after the sample, and the average value was taken as the air blocking property (m / sec).

Transparency of Nonwoven Fabric Five samples of 30 cm square were prepared, and the measurement was performed using 200 W white light as a light source and an illuminometer ANA-300 manufactured by Tokyo Koden Co., Ltd. as an illuminance measuring device. That is, the distance between the light source and the measuring instrument is set to 2000 lux, the sample is placed horizontally at a position of 10 cm above the measuring instrument, the amount of light passing through the sample is measured for each sample, and the average value is transmitted. Luminous (lux).

Compressive Bending Softness of Non-Woven Fabric A total of five sample pieces each having a sample length of 10 cm and a sample width of 5 cm are prepared, and each sample piece is bent in the lateral direction to form a cylindrical body, and each end is joined. The sample thus obtained was used as a sample for measurement of compression stiffness.
Then, for each measurement sample, in the axial direction, a constant-speed elongation type tensile tester (Tensilon U manufactured by Toyo Baldwin Co., Ltd.)
Using TM-4-1-100), compression was performed at a compression speed of 5 cm / min, and the average of the obtained maximum load values (g) was determined.
Then, by dividing this average value by the basis weight of the nonwoven fabric, the compression stiffness per unit basis weight (g / (g /
m ² )).

Example 1 High-density polyethylene having a melting point of 128 ° C. and a melt index of 25 g / 10 min was used as an olefin resin. On the other hand, as an ester resin, the melting point is 258.
Polyethylene terephthalate having an intrinsic viscosity of 0.70 ° C. was used. And the yarn cross section is a composite form shown in FIG.
A high-density polyethylene 1 forms a sheath, a polyethylene terephthalate forms a core 2, and a composite spinneret capable of forming a hollow 3 in the center of the core 2 is used. Is 1: 1 by weight, and the single hole discharge amount is 4.0.
Extruded at g / min. After cooling the spun yarn, it was taken out by air soccer at a speed of 4300 m / min, opened by a known opening device, collected and deposited on a moving collecting surface to obtain a long fiber web. Further, this long fiber web was partially thermocompression-bonded with a hot embossing roller under the conditions of a handle: point, a processing temperature: 120 ° C., and a pressed area ratio: 10%, and a two-component system having a basis weight of 20 g / m ^2. A core-sheath hollow long-fiber nonwoven fabric was obtained.

When the two-component core-sheath hollow fiber collected from the fiber assembly was observed with a microscope, the fiber diameter was 35.9 μm.
m, hollow ratio: 42%, fineness 1: 8.4 denier, fineness 2: 10.2 denier.

Table 1 shows the physical properties of the obtained long-fiber nonwoven fabric.

[0043]

[Table 1]

Example 2 A two-component core-sheath hollow long-fiber nonwoven fabric was obtained under the same conditions as in Example 1 except that the basis weight was changed to 10 g / m ² .

Table 1 shows the physical properties of the obtained long-fiber nonwoven fabric.

Example 3 Single holes were extruded at a discharge rate of 6.0 g / min, and were taken out by air soccer at a speed of 4800 m / min. Otherwise, under the same conditions as in Example 1, the basis weight was 20 g /
m ² of a two-component core-sheath hollow filament nonwoven fabric was obtained.

When the two-component core-sheath hollow fiber collected from the fiber assembly was observed with a microscope, the fiber diameter was 43.2 μm.
m, hollow ratio: 48%, fineness 1: 11.3 denier, fineness 2: 14.7 denier.

Table 1 shows the physical properties of the obtained long-fiber nonwoven fabric.

Example 4 As the olefin resin, a polypropylene polymer having a melting point of 162 ° C. and a melt flow rate of 40 g / 10 min was extruded at a single hole discharge rate of 4.5 g / min, and was extruded at 4500 m / min by air soccer. Min, and the processing temperature of the hot embossing roller was set to 138 ° C. The other conditions were the same as in Example 1, and the basis weight was 2
A two-component core-sheath hollow long-fiber nonwoven fabric of 0 g / m ² was obtained.

When the two-component core-sheath hollow fiber collected from the fiber assembly was observed with a microscope, the fiber diameter was 37.9 μm.
m, hollow ratio: 43%, fineness 1: 9.0 denier, fineness 2: 11.1 denier.

Table 1 shows the physical properties of the obtained long-fiber nonwoven fabric.

Comparative Example 1 Using the same high-density polyethylene and polyethylene terephthalate as in Example 1, bicomponent core-sheath composite fibers having no hollow portion were spun. That is, using a composite spinneret in which high-density polyethylene forms a sheath and polyethylene terephthalate forms a solid core, the composite ratio of high-density polyethylene and polyethylene terephthalate is 1: 1 by weight.
And extruded at a single hole discharge rate of 4.0 g / min. After cooling the spun yarn, it was taken out by air soccer.

As is clear from Table 1, Example 1 is a long-fiber non-woven fabric composed of a two-component core-sheath hollow composite cross-section large-thickness yarn composed of a polyethylene resin and a polyethylene terephthalate resin. , A low-weight nonwoven fabric with excellent mechanical performance, breathability, translucency and quality,
It was suitable as an agricultural nonwoven fabric.

Example 2 is a long-fiber nonwoven fabric made of a large fineness yarn similarly to Example 1 and has a lower weight than that of Example 1, and is therefore also suitable as an agricultural nonwoven fabric. Was.

Example 3 is a long-fiber nonwoven fabric formed by a yarn having a finer fineness than that of Example 1,
It was excellent in mechanical performance, air permeability, translucency and quality, and was suitable as an agricultural nonwoven fabric.

Example 4 is a long-fiber non-woven fabric formed of a bicomponent core-sheath hollow composite cross-section, large-diameter yarn composed of a polypropylene resin and a polyethylene terephthalate resin, and has light weight, mechanical performance, air permeability, It was excellent in light transmittance and quality, and was suitable as an agricultural nonwoven fabric.

On the other hand, in Comparative Example 1, the same two-component resin as in Example 1 was used to obtain a long-fiber nonwoven fabric composed of a fine-filament yarn having a two-component core-sheath composite cross section. Because of the absence, the spun yarn was insufficiently cooled in the spinning step, and adhesion between the yarns occurred, so that a long-fiber nonwoven fabric could not be obtained.

[0058]

The long-fiber non-woven fabric of the present invention is a long-fiber non-woven fabric composed of a bicomponent core-sheath hollow composite cross-section, large fineness yarn of an olefin-based resin and an ester-based resin. It has excellent mechanical performance, air permeability, translucency, and quality, and has a high rigidity per unit weight due to its hollow cross section. In particular, a low-weight nonwoven fabric is suitable as a nonwoven fabric for agricultural use.

[Brief description of the drawings]

FIG. 1 is a schematic view of a two-component core-sheath hollow composite cross-section yarn according to the present invention.

[Explanation of symbols]

 1 sheath part 2 core part 3 hollow part

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masamiko Matsunaga 4-1 Unita Kitamachi, Okazaki City, Aichi Prefecture Unitika Okazaki Plant

Claims (4)

[Claims] 1. A fiber having a fiber diameter of 35 μm or more, and in the cross section of the fiber, an olefin-based resin forms a sheath portion, and the main component is ethylene terephthalate having a melting point of 30 ° C. or more higher than the melting point of the olefin-based resin. The ester-based resin forms a core portion, and the ester-based resin in the core portion has a hollow portion, and is constituted by a long fiber having a two-component core-sheath hollow structure having a hollow ratio of 10 to 60%. A long-fiber nonwoven fabric, wherein constituent fibers are integrated by heat fusion of an olefin resin. 2. An agricultural nonwoven fabric comprising the long-fiber nonwoven fabric according to claim 1, having a basis weight of 5 to 30 g / m ^2.
An agricultural nonwoven fabric characterized by the following. 3. The agricultural nonwoven fabric according to claim 2, wherein the air permeability is 1 m / sec or more. 4. The agricultural nonwoven fabric according to claim 2, wherein the translucent property is 500 lux or more.