JPH0147586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel nonwoven sheet with excellent flexibility and mechanical properties, and a method for producing the same.

Conventionally, a needle punch method has been adopted as one of the methods for manufacturing nonwoven fabrics in which constituent fibers are intertwined.
In this method, a large number of needles with hooks are mechanically pierced perpendicularly into the nonwoven web, and it is possible to intertwine webs with a relatively high basis weight of several hundred g/ ^m2 . However, for relatively low weight products, for example, webs with a weight of 100 g/m ² or less, entanglement is insufficient even if the pricking treatment is performed many times. Moreover, in this case, it is inevitable that the fibers will be cut or damaged during processing, and in addition to the low mechanical properties of the product, the inclusion of a layer of cut fibers will limit its application. It was hot.

As another entangling method, a method is known in which a nonwoven web using short fibers is treated with a high-pressure water stream.
According to this method, in the case of a non-woven web using short fibers, the ends of the staples are easy to move, so they are easily entangled, but they are also easily deformed when an external force is applied to the product sheet, and the surface friction force is applied. When it is wet, the fibers tend to come off easily and the surface fuzz is noticeable. As a result, the product had a problem of low strength, high elongation, and poor abrasion resistance, resulting in a lack of practicality.

In addition, although a technology using long fibers as a material is known as a nonwoven fabric technology, it is generally difficult to cause dimensional changes in the length direction of the fibers when attempting to entangle them by impinging a high-pressure water stream on the long fiber web. As a result, sufficient confounding cannot be obtained.

In view of the background of the prior art, as a result of intensive studies on nonwoven fabrics with excellent mechanical properties and flexibility, the present invention has developed a nonwoven fabric that uses long fibers and has a three-dimensional structure that satisfies specific requirements. They have also found that such a nonwoven fabric can be achieved by using a specific long fiber web and subjecting it to high pressure water jet treatment.

That is, the nonwoven fabric of the present invention has a fineness of 1 denier or more, contains at least 0.5% by weight of water-swellable filaments made of a single component, has an apparent density of 0.1 to 1.0 g/cm ³ , and has a basis weight of 400 g/m ² This is a three-dimensional entangled nonwoven fabric having the following characteristics and an elongation under tension of 50 g per area weight (g/m ² )/5 cm width of 40% or less.

Further, in the method for producing a nonwoven fabric of the present invention, the fineness is 1
A long-fiber nonwoven web containing at least 0.5% by weight of water-swellable filaments made of a single component and having a denier or more is immersed in water for 10 minutes.
This is a method for producing a three-dimensionally entangled nonwoven fabric, which is characterized in that it is treated with a high-pressure water stream of Kg/cm ² or more.

In the present invention, in order to properly entangle the nonwoven web by the high-pressure water treatment described below, the long fiber web is treated with a water-swellable filament having a fineness of 1 denier or more and consisting of a single component. It is necessary to include and form at least one.

In the present invention, water-swellability refers to the property that elongation occurs in the longitudinal direction or diametrical direction when immersed in water. Filament materials having this characteristic include rayon, polyamide, copolymerized polyester, copolymerized polyolefin, and other modified organic synthetic polymers, but polyamide is particularly suitable for the present invention.

That is, when a polyamide filament is immersed in water, it absorbs water and elongates by 1 to 5% in the length direction, and when it is subsequently dried, it returns to its original length. It was discovered that this works extremely synergistically with high-pressure water treatment. In addition, the low bending moment and moderately low surface smoothness of the fibers cause partial elastic elongation of the fibers due to the impact force of the high-pressure water stream, which significantly improves the effect of hydroentangling treatment. It is a fact found.

The present invention takes advantage of such characteristics by immersing the nonwoven web in water before entangling it to cause the constituent filaments to elongate.
By performing a drying treatment subsequent to the entangling treatment, a shrinkage effect occurs, which further strengthens the entanglement and makes it more dense.

The method of pre-immersion treatment in water involves passing through a water tank before high-pressure water treatment, but this causes web disturbance if the filaments are not entangled. Therefore, a method of treatment using a weak columnar flow is appropriate, and it is usually preferable to perform pretreatment with a water pressure of 1 to 50 kg/cm ² that does not lead to complete entanglement.

The present invention is characterized in that the nonwoven web is entangled by high-pressure water treatment. A high-pressure water stream is a columnar stream obtained by ejecting water from pores at high pressure. Such columnar flow typically has a diameter of 0.06
It is obtained by ejecting it at a pressure of 10 to 200 Kg/cm ² from pores with a size of 1.0 mm or more. This columnar flow is usually produced using a nozzle with multiple pores arranged at equal intervals in the lateral direction (width direction of the nonwoven web), or with a large number of pores arranged in multiple rows with the phase of each row of pores shifted as necessary. It is ejected from a nozzle with pores.

The nonwoven web is supported by a receiving mechanism so that the columnar flow impinges vertically on the nonwoven web. This receiving mechanism is usually composed of a wire mesh or a plate-shaped body having a draining structure, and is usually equipped with a constant-speed transfer mechanism such as a conveyor.

Such high-pressure water jet treatment is preferably repeated many times to achieve uniform entanglement in the thickness direction, particularly when treating a nonwoven web with a high basis weight. In this case, the effect can be achieved by consecutively treating one side one or more times, but if the complexity of operating the equipment is acceptable, it is preferable to treat the front and back alternately, which will significantly reduce entanglement and surface density. You can get something excellent. Furthermore, in order to make the surface entanglement uniform, it is effective to oscillate the nozzle having fine holes or the passing web itself in the width direction at a constant cycle and stroke.

Further, as a means for controlling entanglement, there is ejection pressure of a columnar flow. This ejection pressure needs to overcome the mutual binding force of the filaments constituting the nonwoven web and entangle them with each other, and is required to be at least 10 kg/cm ² . For example, if the pressure is higher than necessary, such as 200 kg/cm ² or more, the columnar flow will penetrate the nonwoven web in the thickness direction, causing a part of the filament to get stuck in the hole in the receiving mechanism, or the sheet to be uneven. This can lead to problems such as the formation of pores. Therefore, it is preferable to adjust the degree of entanglement by selecting the ejection pressure and the number of treatments depending on the basis weight of the nonwoven web. At this time, a relatively low water pressure is selected for a low basis weight web, and an effective sheet can be obtained with low energy. For high weight webs, for example, when the weight is 200g/ ^m2, the water pressure is 80 to 150Kg/ ^cm2 , and the weight is 300.
In terms of g/m ² , a high water pressure such as 120 to 170 Kg/cm ² is preferably selected. The present invention can also be applied to non-woven webs with even higher basis weights, for example, even webs with a basis weight of over 400g/ ^m2 .
A water stream with a high water pressure of 200 kg/cm ² or more may be used, but in practice, treatment should be performed with a web of 400 g/m ² or less and a water pressure of 170 kg/cm ² or less, preferably 150 kg/cm ² or less. It is preferable to select a relatively low water pressure from the viewpoint of product quality, workability, etc. In this case, it is preferable to repeat the process at least several times alternately on the front and back sides, since a difference in entanglement tends to occur in the thickness direction of the sheet if the process is repeated a small number of times. A sheet subjected to such treatment is effective in obtaining a structure with less entanglement in the center of the sheet in the thickness direction, and is effective as a means for providing a grain structure in the center of a drain material, for example. This phenomenon can be avoided by setting the water pressure to an even higher level, but with measures to strengthen the pressure resistance of nozzles and water piping,
Increased water flow and other measures to ensure safety and product quality must be taken.

The present invention is characterized in that it provides a nonwoven fabric with excellent entangling properties, which is achieved by treating a nonwoven web made of water-swellable filaments with a high-pressure water stream. However, the filaments constituting the nonwoven web are characterized in that even if they partially contain filaments that are not water-swellable, such as filaments of polyester or polyolefin, the entangling effect is significant.

For example, if the non-swellable material is mixed at a mixing ratio of 0.5% by weight or more, if it is uniformly dispersed, the elongation and contraction of the water-swellable filaments will spread over the entire web, and the web will consist of 100% non-water-swellable filaments. The degree of entanglement is greater than when a non-woven web is used. Therefore, the present invention need not be limited to nonwoven webs consisting of 100% water-swellable filaments.

The three-dimensional entanglement, which is a feature of the present invention, causes the fibers to become entangled, just like tangled fishing lines, and when subjected to external force, it is not only extremely difficult to unravel, but also to become entangled more firmly, resulting in improved washing resistance and durability. It exhibits excellent abrasive properties and can be used as is for clothing and industrial materials.

On the other hand, the entanglement by ordinary needle punching is simply a stabbing effect of the fibers in the thickness direction of the fabric, a so-called riveting effect, and the fibers easily come off, so it is not practical without using other adhesive methods. It has disadvantages that cannot be tolerated.

According to the present invention, the apparent density of the nonwoven fabric obtained can be easily adjusted regardless of the basis weight of the nonwoven web, making it possible to provide a nonwoven fabric suitable for a wide variety of uses. That is, the apparent density is determined by the water pressure and the number of times of treatment in high-pressure water treatment.

The nonwoven fabric of the present invention usually has a weight of 0.1 g/cm ³ to 1.0 g/cm ³
However, if even higher quality is required, a nonwoven fabric having an apparent density of 0.2 to 1.0 g/cm ³ is preferable. As described above, according to the present invention, it is possible to easily form a nonwoven fabric with significantly higher density than the effect of conventional needle punching.

In addition, if a higher density nonwoven fabric is required, subsequent to high pressure water treatment, between a pair of flat plates,
Alternatively, this can be easily achieved by applying pressure between rollers to reduce the thickness, but even in this case, in terms of product quality and properties, the apparent density exceeds the range of 0.1 to 1.0 g/ ^cm3. I don't like that.

The present invention is the first to provide a nonwoven fabric that is flexible and has excellent mechanical properties by subjecting a nonwoven web comprising at least 0.5% by weight of water-swellable filaments to high-pressure water jet treatment.

The present invention will be described in detail below with reference to Examples.

In addition, the measurement method in the examples is based on the method shown below.

[Apparent Density] Calculated from the thickness value and basis weight value measured with a thickness meter under a load of 240g/cm ² .

[Tensile strength, tensile elongation] 5cm wide strip method, tensile speed 10cm/min.

[Weight (g/m ² ) per area: 50g/5cm width. Elongation under tension] The elongation value corresponding to the tensile strength value of sample basis weight x 50 g was read from the tensile strength-elongation curve during tensile strength/elongation measurement.

[Bending resistance] 45° cantilever method.

[Abrasion resistance] Two sheets of size 5 x 20 cm with the same direction are stacked flat with both ends fixed separately.
Surface pressure 24g/cm ² for upper sheet area 5 x 7.5cm
Stroke the lower sheet in the longitudinal direction while
2.5 cm, reciprocating motion at a cycle of 20 cps, and the number of reciprocating motions until fluff appears on the friction part.

Example 1 A randomly arranged nonwoven web made of nylon 6 filaments with a fineness of 1 denier and a basis weight of 103 g/m ² was produced by a method of melt spinning, taking up with an air ejector, and collecting on a wire mesh. This web is transferred to a conveyor made of 100 mesh wire mesh at a speed of 0.7 m/min.
Water flow treatment was performed at a water pressure of 45 kg/cm ² to entangle. In this case, the nozzle has a hole diameter of 0.1 mm, a hole number of 500, and a hole pitch.
0.9mm, the hole arrangement is in one row in the width direction of the web, the nozzle swings in the same direction at a cycle of 7 cps, and a stroke of 1.5
mm, and the distance between the lower surface of the nozzle and the nonwoven web was 5 cm.

After the above water treatment (first time), turn it over and perform the same treatment for the second time, and further increase the water pressure to 80Kg/cm ²
The table shows the water flow treatment from the 3rd to the 6th time.
It was carried out alternately on the back. After the above water treatment, further temperature
It was dried with hot air at 105°C.

The obtained nonwoven fabric had excellent flexibility and mechanical properties as shown in Table 1, and was suitable for use as a leather base fabric and other clothing.

(Table 1) Apparent density: 0.29 (g/cm ³ ) Tensile strength: 48 (Kg/5cm) Tensile elongation: 78 (%) Elongation under tension of 50g/5cm width per area weight (g/m ² ): 8 (%) Hardness Softness: 48 (mm) Abrasion resistance: 920 (times) Comparative example 1 A nonwoven fabric made of nylon 6 with a fineness of 1 denier, a fiber length of 51 mm, a crimp count of 18 threads/inch, and a basis weight of 103 g/ ^m2 . A woven web was subjected to high-pressure water treatment and drying treatment under the same conditions as in Example 1. The obtained nonwoven fabric not only lacked mechanical properties, but also lacked flexibility and abrasion resistance, making it unsuitable for practical use.

(Table 2) Apparent density: 0.25 (g/cm ³ ) Tensile strength: 18.0 (Kg/5cm) Tensile elongation: 116 (%) Elongation under tension of 50g/5cm width per area weight (g/m ² ): 68 (%) Hardness Softness: 47 (mm) Abrasion resistance: 230 (times) Comparative Example 2 Melt-spinning a randomly arranged nonwoven web made of polyethylene terephthalate filaments with a fineness of 1 denier and a basis weight of 103 g/m ² - Air ejector It was produced by the method of taking over and collecting on a wire mesh, and subjected to water flow treatment and drying treatment under the same conditions as in Example 1. As shown in Table 3, the obtained nonwoven fabric lacked flexibility and abrasion resistance, and was poor in practical use.

(Table 3) Apparent density: 0.28 (g/cm ³ ) Tensile strength: 45 (Kg/5cm) Tensile elongation: 76 (%) Elongation under tension of 50g/5cm width per area weight (g/m ² ): 10 (%) Hardness Softness: 57 (mm) Wear resistance: 170 (times)

Claims (1)

[Claims] 1. Contains at least 0.5% by weight of water-swellable filaments made of a single component with a fineness of 1 denier or more, an apparent density of 0.1 to 1.0 g/cm ³ , and a basis weight of
400g/m2 or ^less , and 50 per unit weight (g/ ^m2 )
A three-dimensional entangled nonwoven fabric characterized by an elongation of 40% or less under tension at a width of g/5cm. 2. The three-dimensional entangled nonwoven fabric according to claim 1, wherein the water-swellable filament is a polyamide filament. 3. A long-fiber nonwoven web having a fineness of 1 denier or more and containing at least 0.5% by weight of water-swellable filaments made of a single component is soaked in water in advance and then treated with a high-pressure water stream of 10 kg/cm ² or more. A method for producing a three-dimensionally entangled nonwoven fabric.