JPH01321966A - Manufacturing method of nonwoven fabric - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing a high-strength nonwoven fabric made of continuous filaments.

BACKGROUND OF THE INVENTION Non-woven fabrics are used in various fields such as agriculture, civil engineering, construction, etc., and high-strength non-woven fabrics are sometimes required depending on the application.

In order to produce a high-strength nonwoven fabric, it is sufficient to stretch the filaments that make up the nonwoven fabric to increase the strength of the filaments.From this perspective, we added a stretching process to the method for producing spunbond nonwoven fabrics, and the filaments were roll-stretched. is known (Special Publication No. 49-43506).

Problems to be Solved by the Invention When drawing filaments, thread breakage due to drawing,
Due to insufficient cooling, filaments tend to stick to each other, and sticky filaments adhere to the stretching roll, which tends to cause yarn breakage, making uniform stretching difficult. Therefore, the appearance of the nonwoven fabric deteriorates, the strength decreases, and quality problems tend to occur.

Nonwoven fabrics obtained from stretched filaments also have improved tensile strength and deformation coefficient (Young's modulus, a coefficient that indicates difficulty in elongation) in the machine direction (longitudinal direction), but are insufficient in the transverse direction. The vertical and horizontal strength becomes unbalanced.

An object of the present invention is to solve the above-mentioned problems and provide a method for manufacturing a nonwoven fabric that has high strength and can balance the strength in the longitudinal and lateral directions.

Means for Solving Problems In order to achieve the above object, the present invention stretches a web made of continuous filaments in the direction of web flow using a stretching device, and then laminates the obtained stretched webs so that the stretching directions intersect with each other. It is bonded.

The web made of continuous filaments used in the present invention has a fineness of 1 to 20 deniers, preferably 3 to 15 deniers, and a basis weight of 15 to 100 g/n (preferably 20 to 50 g/n).
rJ and a tensile strength ratio of 0.8 to 4 in the longitudinal and lateral directions, and bonding of the web is performed by, for example, heat embossing, needle punching, water jet punching, ultrasonic welding, or the like.

A web stretching device is usually composed of rollers having different circumferential speeds. In this case, the web threading method may be either the nip method or the S-curve threading method.

For polypropylene, the stretching temperature is 140 to 60°C.
A range of is appropriate.

The higher the stretching ratio is, the more desirable it is, but if it is too high, the stretch of the unibu will break, so it should be kept at about 2 to 4 times.

FIG. 1.2 shows an example of a stretching device used in this method and a crosslay device provided on the delivery side thereof.

That is, as shown in FIG. 1, the stretching apparatus has a roll 3 having a higher circumferential speed than the roll 2 on the delivery side of an induction heating type heating roll 1.2, and a roll 4 on the delivery side.
．． An infrared heater 7 is arranged at 5 to heat the web 6 being passed. 8 is a roll on which the original web is wound; the web 6 fed out from this is heated by an infrared heater 7 and a heating roll 1.2, and then stretched between rolls 2.3 of a stretching section; It is adapted to be transferred to a Crossray device.

As shown in FIG. 2, the crosslay device includes a heald conveyor 11 that is lined up in a row on the left and right and conveys the web 6 in the right direction, and reciprocates left and right on the delivery side of the conveyor.
A held con hair 12 that folds the web 6 sent out from the belt con hair 11 while conveying it in the left direction, and is arranged below the con hair 12 orthogonally to the con hair 11.12,
Similar to the web 6, it is composed of a heald conveyor 13 that conveys a longitudinally stretched web 14 to the front side, and the web 6 folded by the conveyor 12 is little by little on the web 14 that is conveyed to the front side by the belt conveyor 13. It is designed to be folded and transported while being shifted.

Thus, the web 14 and the web 6 folded over this
In other words, the stretching direction is perpendicular to the drawing direction.

In another device that intersects the stretching direction of the web, the web stretched by the stretching device is cut into pieces of a certain length, and the cut pieces are placed on the web conveyed by a belt conhair with the stretching direction crossed so that a portion of the web is are stacked so that they overlap.

In yet another method of intersecting the stretching direction of the web, the web 6 stretched by the stretching device is directly folded and stacked on the belt conveyor 13 while being shifted. In this case, the stretching directions will intersect at an acute angle, which will change the speed of the belt 6 and/or the belt 6.
This can be changed by changing the feeding speed.

The webs laminated in such a way that the centrifugal directions intersect are then molded, and this molding is carried out, for example, by heat embossing, needle punching, water jet punching, ultrasonic welding, etc., similar to the web described above. be exposed.

Effect When a web made of continuous filaments is stretched in the machine direction, the filaments are arranged in the centrifugal direction and the filaments themselves that make up the web are stretched. This causes the tensile strength and deformation coefficient in the machine direction (longitudinal direction) to decrease. improves.

When the obtained stretched webs are laminated and bonded so that the stretching directions intersect with each other, the strength in the longitudinal and lateral directions is increased. Further, the strength balance in the vertical and horizontal directions can be changed by changing the intersection angle when laminating the layers.

Example 1 A continuous superfiber nonwoven fabric with a fineness of 6 denier and a basis weight of 40 g/r+ (was stretched twice in the longitudinal direction using a stretching device, and then transferred to a crosslay device and laminated so that the stretching directions cross each other.

Next, the laminated web was bonded using a needle punch machine to obtain a nonwoven fabric with a basis weight of 400 g/n. The physical properties of the nonwoven fabric and the unstretched nonwoven fabric are shown in Example 1 and Comparative Example 1 in the table.

Example 2 A continuous superfiber nonwoven fabric with a fineness of 6 denier and a basis weight of 25 g/rd is stretched twice in the longitudinal direction using a stretching device, and then transferred to a crosslay device and laminated so that the stretching directions cross each other.

Next, the laminated web was bonded using a needle punch machine to obtain a nonwoven fabric with a basis weight of 200 g/rrI. The physical properties of the nonwoven fabric and the unstretched nonwoven fabric are shown in Example 2 and Comparative Example 2 in the table.

Effects of the Invention The present invention is configured as described above, and has the following effects.

According to the method of claim 1, a web made of continuous filaments is stretched in the machine direction, and then laminated and bonded so that the stretching directions intersect, thereby achieving strength balance in the longitudinal and lateral directions and eliminating anisotropy. It is now possible to obtain a high-strength nonwoven fabric, which is suitable for use in fields where loads are applied in the vertical and horizontal directions, such as civil engineering materials, especially soft ground surface treatment materials, and suction prevention materials.

According to the method of claim 2, the longitudinal and lateral strength balance can be changed by changing the crossing angle of the stretching direction.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of the stretching apparatus used in the method of the present invention, and FIG. 2 is a perspective view of the crosslay apparatus. 1.2...Heating roll 3.4.5.8.9...Roll 6...Web 7...Infrared heater 11.12
．． 13. Held conveyor applicant Mitsui Petrochemical Industries Co., Ltd. agent Patent attorney Akira Sato −

Claims (2)

[Claims] (1) A method for producing a nonwoven fabric, characterized in that a web made of continuous filaments is stretched in the machine direction of the web using a stretching device, and then the resulting stretched webs are laminated and bonded so that the stretching directions intersect with each other. (2) The method for producing a nonwoven fabric according to claim 1, wherein the crossing angle of the stretching direction during lamination is changed.