JP3147633B2 - Non-woven and civil engineering materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high-quality
The present invention relates to a nonwoven fabric having high physical properties, and more particularly, to a needlepunched nonwoven fabric for civil engineering materials having excellent tensile strength and alkali resistance.

[0002]

2. Description of the Related Art A continuous filament spun from a spinneret is pulled at high speed by air soccer or the like, then charged and charged on a collision plate mainly composed of lead, and after the filament is woven, collected on a moving net conveyor. Generally, a nonwoven fabric is formed by partially thermocompression bonding with a heated embossing roll to form a nonwoven fabric, or a nonwoven fabric obtained by mechanically entanglement of a laminated web collected on a net by needle punching. In particular, nonwoven fabrics mechanically entangled by needle punching are high in strength and excellent in water permeability and workability, and the demand for drainage and durability after construction of roads and tunnels is increasing.

[0003] Nonwoven fabrics for civil engineering materials have a strong demand for high quality nonwoven fabrics with little spotting because partial sheet defects greatly affect the performance after construction, and are conventionally excellent in nonwoven fabric productivity and physical properties. A long-fiber non-woven fabric mainly composed of polyester has been used. However, in recent years, when a polyester-based spunbond nonwoven fabric is used as a tunnel drainage material, there is a concern that the polyester may be dissolved and deteriorated by alkali flowing out of cement used during construction, and there is a strong demand for a polypropylene nonwoven fabric.

For the production of a polypropylene nonwoven fabric, there is a method in which a filament spun from a die is pulled at high speed by air soccer or the like and collected on a net which moves directly. Inferior, a method in which a spun filament is pulled by a rectangular air sucker using a rectangular die in which the die hole array is uniformly arranged in the width direction, and further passed through ionized air in order to improve the openability of the filament. Alternatively, a method of directly applying a high voltage to charge has been proposed.

[0005]

However, in the above-mentioned method for producing a non-woven fabric containing polypropylene as a main component, it is not enough to impart a sufficient electric charge to the filament and also to apply such a high voltage. Adopting the method of charging has the disadvantages that the equipment cost is high, the risk is high, and the workability is poor.

[0006] Polypropylene has a lower melting point than polyester resin, and the spun filament is hardly cooled and solidified.
Since the filament rubs against the air soccer and the filaments fuse together, the spinning speed is 2,000 to 300.
At a low level of 0 m / min, the obtained nonwoven fabric has a high elongation and a low strength. As a method of improving the physical property level of these nonwoven fabrics, after mechanically entanglement of a long fiber laminated web collected on a net by needle punching, the width direction of the nonwoven fabric in an atmosphere heated to a temperature close to the melting point and There is also a method of stretching in the length direction,
Not only is the process long and equipment costs are high, but running costs are high.In addition, since the nonwoven fabric is stretched in the width and length directions, filaments are oriented horizontally and the thickness of the nonwoven fabric is reduced. It was not satisfactory.

An object of the present invention is to solve these problems and to provide a method for stably producing a high-quality polypropylene fiber nonwoven fabric which is low in cost and free of spots.

[0008]

According to the present invention, as a result of intensive studies on the spinning cooling behavior of the polypropylene polymer and the polyester-based polymer and the charging behavior of the filament after spinning, the behavior of the polyester-based polymer was no problem at all. On the other hand, paying attention to the fact that polypropylene polymer shows remarkably bad behavior, and utilizing this behavior difference skillfully, it is possible to provide high-quality nonwoven fabric that is capable of high-speed spinning, has excellent spreadability, and has no spots. Is a successful one.

That is, the present invention takes advantage of the characteristics of each of a polypropylene polymer and a polyester polymer by forming a specific fiber structure of a core-sheath composite polypropylene fiber in which a polyester is disposed in a sheath portion. is there.

[0010] The composite polypropylene fiber filament of the present invention preferably has a fineness of 2 to 10 denier, more preferably 2 to 8 denier. When the fineness of the filament is less than 2 denier, the spinning stability is reduced. In addition to chipping, there is a problem that the thickness of the nonwoven fabric that has been needle-punched is thin and easy to set, thereby lowering water permeability. If the fineness of the filaments exceeds 10 deniers, cooling during spinning becomes insufficient, so that the filaments are fused to each other and the weaving property is deteriorated.

The basic idea of the present invention is that, in the thermoplastic continuous filament constituting the nonwoven fabric, the polypropylene as the core component is for improving the chemical performance such as alkali resistance, and the polyester resin as the sheath component is not used. A so-called core-in-sheath type conjugate fiber which covers the entire surface of the polypropylene-based resin, and the polyester-based resin as a sheath component is for imparting heat resistance and chargeability to the continuous filament. Therefore, the basic requirement is to have a core-sheath structure in which the polyester resin as the sheath component covers the entire area of the polypropylene resin as the core component, and the cross-sectional shape of the core component and the sheath component is irregular, such as circular or triangular. Any form of cross section may be used. However, when the bimetal structure or a part of the polypropylene resin is exposed on the surface of the filament, the function of each resin is reduced, so that it is difficult to obtain a high quality nonwoven fabric.

The polyester resin used in the present invention includes polyethylene terephthalate or isophthalic acid,
Any resin may be used as long as it has heat resistance and chargeability, such as a polyester copolymerized with adipic acid. If necessary, a third component such as a weathering agent, a heat stabilizer, a pigment, and a charging agent may be added. Needless to say, this is acceptable.

[0013] The polypropylene resin used for the core component is also generally available on the market and can be used satisfactorily. Even if the third component additive is used as in the case of the sheath component, there is no problem.

In the continuous filament of the present invention, the weight ratio of the core component and the sheath component is such that the sheath component 5
Preferably it is up to 25 parts. When the sheath component is more than 25 parts with respect to 100 parts of the core component, there is no problem in producing the nonwoven fabric such as spinning and needle punching, and there is no problem in the physical properties of the nonwoven fabric such as tensile strength and elongation. In the case of, the ratio of polypropylene as the core component decreases as the ratio of the polyester resin as the sheath component increases, which is disadvantageous in terms of chemical resistance. On the other hand, if the sheath component is less than 5 parts, due to a difference in the melt viscosity of the core component or the sheath component resin or a change in the discharge amount, etc.
It becomes difficult for the sheath component resin to completely cover the periphery of the core component resin, and in some cases, there is a tendency that filaments composed of only the polypropylene as the core component are mixed. In such a case, as in the case of spinning with a single component of polypropylene, the cooling of the mixed filaments is insufficient and fusion between the filaments occurs, and even if the pressure of air sucker is increased, the spinning speed is not increased, and the filament speed is not increased. Since the properties are easily deteriorated, and the polyester resin with good chargeability does not completely cover around the polypropylene resin with poor chargeability, the chargeability is reduced even if it collides with a collision plate mainly containing lead. Of the nonwoven fabric cannot be obtained, for example, the opening of the nonwoven fabric becomes insufficient and the unevenness of the weight of the nonwoven fabric deteriorates.

The nonwoven fabric of the present invention can be produced freely as long as it is an ordinary two-component composite spinning apparatus. The air soccer for high-speed traction may be round or rectangular. It can be easily made by a polyester-based nonwoven fabric manufacturing apparatus.

According to the method of the present invention, it can be produced by using a conventionally known composite spinning apparatus, has better spinnability than spinning of a single component of polypropylene, and does not generate fusion even at high speed spinning. A nonwoven fabric with good openability and good quality can be obtained simply by collisionally charging a collision plate containing lead as a main component without applying a high voltage and charging positively. Also, high-speed spinning of about 5000 m / min is possible without any problem, and there is an advantage that a nonwoven fabric having high physical properties can be obtained without heating and drawing after needle punching. Further, since the core component is composed of a polypropylene resin, it is possible to provide a nonwoven fabric of high quality and high physical properties applicable to a wide range of fields requiring alkali resistance, such as for tunnel materials and civil engineering materials.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples. The method of measuring characteristic values shown in the examples is as follows.

(1) Tensile strength of nonwoven fabric (kg / 5cm width),
Tensile elongation (%) In accordance with the nonwoven fabric and interlining test method, grip a 5 cm piece of data and measure at a spacing of 10 cm and a tensile speed of 20 cm / min. Measure 5 pieces / m in the vertical and horizontal directions, and average the average of each. This is the value taken.

(2) Filament strength (g / d) and tensile elongation (%) Filaments were measured at a grip interval of 10 cm and a tensile speed of 20 cm / min based on the tensile test method of JIS L1096. The strength is the value obtained by dividing the strength by the denier of the filament.

(3) Unevenness The nonwoven fabric having a length of 100 cm in the horizontal direction and a width of 100 cm in the horizontal direction are equally divided into 20 equal portions in increments of 5 cm, and 400 small pieces each having a size of 5 cm are weighed. The eye spot was calculated by the following equation.

[0021]

(Equation 1) (4) Spinnability Single yarn breakage at each level was investigated. If the number of single yarn breaks was 5 times / ton or less, 、, 6 times / ton to 20 times / ton
Tons were rated as Δ, and those of 20 times / ton or more were rated as ×.

(5) Opening property When a filament pulled by one weight air soccer collides with a collision plate and is collected on a net, the filament having a width of 41 cm or more is collected as ○, 25 cm or more. 40cm
Was evaluated as Δ, and that of 24 cm or less was evaluated as ×.

Examples 1 to 7 Polyethylene terephthalate having an intrinsic viscosity of 0.66 and a melting point of 262 ° C. and an ASTM having a density of 0.90 g / cm ³ .
Melt flow rate by D-1238 (L) method is 3
0, a polypropylene having a melting point of 168 ° C. is melted by a separate extruder, and then a core-sheath type die having a discharge hole of 0.5 mmφ is used, and a core component is polypropylene and a sheath component is polyethylene terephthalate. A filament having a structure was spun. After cooling the spun filament, adjust the pressure of the air soccer so that the spinning speed becomes 5000 m / min. Injection, collection, and nonwoven webs. At this time, the ejection amount of the core component and the sheath component was changed, and the ratio of the core component and the sheath component was 1
/0.25 become like while adjusting denier filaments 1d, 2d, 3d, 5d, 8d, 10d, a 12d and nonwoven basis weight is 200 g / m ^2, is subsequently needle number by needle punching machine Needle punching was performed to obtain 60 needles / cm ² . Table 1 shows the properties and spinning stability of the nonwoven fabric thus obtained.

[Table 1] In this embodiment, the filament fineness is 2d to 1
In the case of 0d, the filaments were sufficiently unwoven without fusion of the filaments, so that the nonwoven fabric had good spotting unevenness and high tensile strength, all of which were satisfactory for use in civil engineering materials.

Comparative Examples 1 to 4 ASTM-D- at a density of 0.90 g / cm ³ as in Example 1.
A polypropylene having a melt flow rate of 30 by the 1238 (L) method and a melting point of 168 ° C. was spun using a single component die. After cooling the spun filament, the pressure of the air soccer was increased to 2 kg / cm ² , 3 kg / cm ² , 4 kg / cm ² ,
After towing at 5 kg / cm ² , the lead was collided with a collision plate as a main component and collected on a net conveyor.

The obtained nonwoven fabric was subjected to the same needle punching as in Example 1. The characteristics and spinning conditions of the obtained nonwoven fabric are shown in Comparative Examples 1 to 4 in Table 2.

[0026]

[Table 2] As is clear from Table 2, air soccer pressure 4kg / cm
^{In the case of 2} or more, air soccer and filaments are fused by friction of filaments, and the pressure is 3kg /
Those having a size of less than ² cm2 were not satisfactory for use in civil engineering materials having high strength and low elongation, although the filaments were unwoven but the spots were poor.

Comparative Example 2 A positive charging device was installed above air soccer, -15
A nonwoven fabric was obtained in the same manner as in Comparative Example 1 except that KV was applied and charged. The obtained nonwoven fabric was as high as that of Comparative Example 1 and low in strength.

[0028]

Since the nonwoven fabric of the present invention is a filament comprising polypropylene as a core component and a polyester resin as a sheath component, it can be easily produced by a conventionally used two-component conjugate fiber spinning apparatus. It is possible to provide a product having extremely good spots, characteristics and excellent alkali resistance.

Claims (6)

(57) [Claims] 1. A non-woven fabric characterized by laminating polypropylene fibers whose surfaces are coated with a polyester resin. 2. The nonwoven fabric according to claim 1, wherein the fiber fineness is 2 to 10 denier. 3. The nonwoven fabric according to claim 1, wherein the amount of the polyester resin is in the range of 5 to 25 parts with respect to 100 parts of polypropylene. 4. The nonwoven fabric according to claim 1, wherein the nonwoven fabric has a basis weight of 80 g / m ² or more. 5. The nonwoven fabric according to claim 1, wherein the nonwoven fabric is for civil engineering materials. 6. A civil engineering material comprising a nonwoven fabric in which polypropylene fibers whose surfaces are coated with a polyester resin are laminated.