JPS63282351A - Bulky long fiber 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 nonwoven fabric made by spinning a meltable polymer and forming a web as it is without forming it into short fibers.

More specifically, the present invention relates to a bulky long-fiber nonwoven fabric in which crimped long fibers are used and each long fiber is sufficiently dispersed.

[Conventional technology]

Currently, spunpond nonwoven fabrics are widely used for various purposes. However, since the filaments used in these spunbond nonwoven fabrics are not crimped, the bulkiness of the obtained nonwoven fabrics is poor. Demand is increasing. For example, thin and flexible bulky spun nonwoven fabrics may be usefully used as the top sheet of disposable diapers (the sheet that touches the skin) or the top sheet of sanitary products due to their good texture. In addition, hard materials can be used to improve drainage in soil, and when polyolefins and other highly lipophilic materials are used,
It can be usefully used as an oil catch material for wastewater purification.

Bulky nonwoven fabrics themselves can generally be made by creating a web of crimped short fibers (for example, Chisso ES fiber) using a card type web machine, and then using an appropriate lnding method such as hot air bonding. .

However, since spunbond nonwoven fabric is made by directly forming a long fiber web without passing through short fibers, it has physical properties such as strong fabric strength and no short fibers falling off due to breakage of the bonding part, and is easy to manufacture. It has many advantages compared to card-type staple fiber nonwoven fabrics, such as high elasticity and low production costs due to short production processes. Therefore, various agricultural methods have been proposed to provide bulky long-fiber nonwoven fabrics.

For example, Japanese Patent Publication No. Sho 62-1026 describes an ejection hole for ejecting a fiber-forming fluid together with a pressurized fluid, a crimp section consisting of a ventilation wall provided at the tip of the ejection hole, and a section around the crimp section that is Production of a long fiber nonwoven fabric having full crimps from a pressurizing chamber for creating a pressurized atmosphere, and an ejection hole provided at a position opposite to a crimping section for ejecting the buckled crimped yarn while opening and unraveling it. An apparatus is disclosed. By using this device, a long-fiber nonwoven fabric consisting of substantially opened long fibers having a number of crimps of 5 to 25 crimps/25 cm and a crimp degree of 2 to 30% due to buckling crimping can be obtained. It is said that it can be obtained.

Furthermore, JP-A-48-1471 discloses that after spinning, two types of polymer compositions having different contractility are composite-spun into a bimetal type or eccentric sheath-core type, or a polymer composition is spun. The filament is spun to have a biased temperature gradient within the cross-section of the yarn, and the substantially stretched continuous filament obtained by continuous high-speed drawing is created by the action of a high-speed airflow that guides the filament to the outside. It is deposited on the collection surface by heating or solvent treatment with at least 5 crimps/inch and 2% or more of crimped elastic straw on the collection surface, and if necessary, turbulence is applied. A method of forming a mat-like web in which continuous filaments are arranged in a random loop shape, including processing, is disclosed.

In manufacturing the long fiber nonwoven fabrics disclosed in the above two publications, crimped filaments are simply deposited on a collecting surface.

The spreadability of the filaments in the obtained nonwoven fabric is not sufficient, resulting in a so-called multifilament state in which many filaments spun from the same spinneret are bundled without being spread into a single filament. 9. It will be deposited on the collection surface as it is. As a result, the uniformity of the filaments in the nonwoven fabric is poor.

In addition, in order to obtain a wide nonwoven fabric that can be put to practical use by using the above-mentioned method, it is necessary to arrange a large number of spinning devices having the above-mentioned structure on a collecting surface, and the spinning devices are removed one by one. This solves the problem that the boundary portion of the formed web has uneven basis weight and joints compared to other portions, resulting in poor uniformity of the resulting nonwoven fabric.

Of course, in order to solve the above two problems, it is possible to consider a solution in which the number of filaments spun by one spinning device is reduced to several, and many spinning devices are arranged side by side. It is actually difficult to arrange the fibers within the width of the fibers due to collision of devices, and it is difficult to obtain a high-quality bulky long fiber nonwoven fabric.

Thus, a long fiber nonwoven fabric having crimps and having high grooves and high uniformity without knots is currently not available.

[Problem that the invention seeks to solve]

An object of the present invention is to solve the problems of conventionally known long fiber nonwoven fabrics and to provide a bulky long fiber nonwoven fabric that is free from knots and has high uniformity due to the use of crimped long fibers.

[Means for solving problems]

The object of the present invention is achieved by a uniform bulky long-fiber nonwoven fabric that is composed of a plurality of continuous filaments having a number of crimps of 2 to 30 per 25 m, is free from knots, and has a basis weight dispersion index of 80 or less.

The basis weight dispersion index mentioned here refers to any location on the nonwoven fabric.
A triangular square is cut out, and this square nonwoven fabric piece is further cut vertically and horizontally at intervals of Ion to make 25 pieces of 1α3 square nonwoven fabric pieces. The value is obtained by measuring the weight of 25 pieces of nonwoven fabric, dividing the difference between the maximum value and the minimum value by the average value of the 25 pieces, and multiplying that value by 100. Also, the number of crimp is JI
Expressed by the method specified in S.

As mentioned above, the number of crimp filaments used in the bulky long fiber nonwoven fabric of the present invention is 2 to 30 crimps/25 m, preferably 3 to 20 crimps/25 m.

If the number of crimps is small, there is no bulkiness, and even if a bulky nonwoven fabric is obtained by devising a bonding method or the like, the bulkiness of the nonwoven fabric deteriorates when subjected to repeated loads. In other words, the bulk recovery property is low. If the number of crimp is too large, the bulkiness will be too small and the entanglement between the filaments will be too strong, so joints will easily occur and the nonwoven fabric will have a high basis weight dispersion index.

A nonwoven fabric with a low basis weight dispersion index of 1 has good uniformity, and when it exceeds 80, the uniformity is poor and it is practically unusable as a bulky long fiber nonwoven fabric.

The thickness of the nonwoven fabric varies depending on the application. That is, a thin nonwoven fabric such as a top sheet of a diaper needs to have a particle diameter of 0.5 or more for practical purposes, while an oil catch material preferably has a particle diameter of 10 or less from the viewpoint of ease of handling and economical efficiency.

If the bulk density of the nonwoven fabric is 0.1 i/cc or more, it can be obtained with a normal long fiber nonwoven fabric, and there is no need to use filaments with crimp, and -1 bulk density 0.001
, iil/cc or less is too soft and difficult to handle as a nonwoven fabric, and cannot be put to practical use.

Next, a method for producing a bulky long fiber nonwoven fabric according to the present invention will be explained.

FIGS. 1 and 2 show an example of a device for digging a bulky long fiber nonwoven fabric of the present invention.

A method for obtaining continuous filaments with 2 to 30/25 apparent crimps used in the nonwoven fabric according to the invention is the combination of different thermoplastic polymers, such as polyethylene, polypropylene, polyethylene.

Polyethylene terephthalate, various polyamides.

It can be obtained by converting polyethylene, copolymers containing the above-mentioned various polymers as main components, and mixtures thereof into translational composite type or eccentric sheath-core composite filaments. Further, even if the same type of polymer is used, the degree of polymerization or additives may be changed to make a translational composite type or an eccentric sheath-core type composite filament. In the above two methods, the combination of polymers and their proportions may be determined so as to obtain the desired crimp. Furthermore, by using a single-component polymer, filaments with apparent crimp may be obtained by non-uniform cooling during spinning, rubbing on one side of the filament group, or the like. Regardless of which method is used, continuous filaments having 2 to 30/25 crimps can be obtained by selecting appropriate conditions.

Note that the term "actual crimp" as used herein refers to crimp that has already appeared after the yarn has been spun and deposited on the collection surface of a web conveyor, etc., and it also refers to the so-called latent crimp that occurs due to heating, stretching, solvent treatment, etc. It is different from contraction.

When spinning continuous filaments having the above-mentioned apparent crimp, a large number of round spinnerets 1 may be arranged as shown in FIG. 1, or a large number of spinnerets 1 may be arranged over the entire rectangular surface as shown in FIG. A spinning nozzle 1' may also be used. After spinning, the filament group consisting of a plurality of filaments is formed into a comb-like filament group 5 using a rectangular air sucker 2 shown in FIGS. 1 and 2, preferably with a corona shown at 3 in FIGS. After passing through a charging device and dispersing the filaments by charging, the filament group 5
' is deposited in a blind state on a moving collection surface such as a wire mesh web conveyor 4 to obtain a long fiber web 6. Instead of the corona charging device, a frictional charging plate may be used to disperse the filaments.

It is essential to uniformly form the filament group 5 in the shape of a webbing in order to obtain a uniform bulky long fiber nonwoven fabric having a basis weight dispersion index of 80 or less, which is at risk of knotting, according to the present invention. To this end, as the rectangular air sucker 2, a rectangular filament group traction device with a narrow cross section (hereinafter referred to as rectangular high-speed airflow traction device) disclosed in Japanese Patent Publication No. 48-38025 by the same applicant as the present invention is used. Good to use. FIG. 3 shows a cross-sectional view of the jet device 7 of the rectangular high-speed airflow traction device. As shown in FIG. 3, the jet device consists of a male member 8 and a female member 9 disposed downstream of the male member 8 with an interval between them. There is a gap between the jet nozzles 11a and 11b, into which compressed air is introduced as shown. On the other hand, in the center of the male member 8 is a conductive path 1 for air suction and filament guidance.
0 is set. A group of filaments 5 which are extruded into the air by the spinning device and are in a loose state are connected to the conduction path 1.
-) Jet injection holes 11a, l
It is affected by this air jet which is blown from both sides in a flat plate shape. Due to the action of this air jet, air at atmospheric pressure is sucked through the conduit 10 and mixed with the air jet flow. The air jet jet flow is at a high speed close to the sonic speed region, and the filament groups arranged in a generally slanted manner are guided through the jet chamber 12 without mutual entanglement, even if the filament groups have crimps. It is sent downward from channel 13 and deposited on collection surface 4 shown in FIG. 1 or 2.

When it is necessary to obtain a wide nonwoven fabric web, the above-mentioned rectangular high-speed airflow traction device having a rectangular cross section long in the width direction according to the width of the nonwoven fabric can be used to form a uniform interdigital filament group, thereby achieving an unobtrusive basis weight. A uniform bulky long fiber nonwoven fabric with a dispersion index of 80 or less can be obtained.

〔Example〕

Examples of the bulky long fiber nonwoven fabric according to the present invention will be described below along with a method for producing the same.

Note that the definitions and measurement methods of physical property values used in this specification are collectively shown.

◎Basic weight: The weight per inch of nonwoven fabric is indicated by I.

◎Thickness: Measure at least 5 points on the nonwoven fabric using a thickness measuring machine.5 g
The thickness is measured when a pressure of 1/cm" is applied for 10 seconds, and is expressed as the average value.

◎Bulk density: Example 1 120g/120g of polyethylene terephthalate [ηsp/c ''' 0.70, (measured at 25°C using orthochlorophenol as a solvent)] was obtained from one of the two extruders (4).
From the other extruder (B), high-density polyethylene [specific gravity 0.966 (MF'R35JISK72
10 (measured under the conditions shown in Table 1)] was quantitatively extruded at 801/min using a 200-hole spinning nozzle (100 lines in the longitudinal direction and 2 equally spaced in the width direction) as shown in Fig. 2. : A group of translational composite filaments is spun by using a spinneret for translational composite filaments with a longitudinal direction of 803 and a width of 43, and this is passed through a rectangular high-speed airflow traction device 2.
After being pulled at a speed of 3500 m/ynin using a corona charging device and charged by a corona charging device, a receiving web is produced on a wire mesh web conveyor 4 equipped with a moving suction device. The obtained web was a uniform, bulky, long fiber web without knots. The filaments pulling the web had an average number of crimps of 5/25.

This web was sandwiched between two wire meshes and heated at 160°C for 90 seconds in a chain air opener, resulting in a wrinkle weight of 75g/
A uniform long-fiber nonwoven fabric having a thickness of 0.4cfR and a bulk density of 0.0191/CA was obtained.The fabric weight fraction index of this nonwoven fabric was 45.

Example 2 A nonwoven fabric was obtained in the same manner as in Example 1 except that it was received on a web conveyor without being charged with a corona charging device. The obtained nonwoven fabric has a thickness of 0.35 cIn and a bulkiness of 0.02.
2. It was a uniform long fiber nonwoven fabric of lir/cc and had a crease weight dispersion index of 75.

Example 3 As in Example 1, the extruder (4) produced polypropylene (
Specific gravity 0.910, (MFR35JISK7210.
Measured under conditions 14 in Table 1)], polyethylene from the extruder (J3) [specific gravity 0.963. MFR45 (JIS7210
In Table 1 Condition 4, each condition 4 is 100. Quantitative extrusion at a rate of li'/min was carried out using the same spinneret device as in Example 1 and a rectangular high-speed airflow traction device at a speed of 3.800 m/min. After colliding with an alloy plate to cause frictional electrification, it was deposited on a moving web conveyor. The obtained web was a uniform and bulky web with good filament spreadability and no knots, and the average number of filament crimps was 4/25 m.

By heating at 150°C for 50 seconds in the same manner as in Example 1, a bulk density of 0 with a crease area of 32 g/m'' and a thickness of 0.0951 was obtained.
．． A bulky and uniform long fiber nonwoven fabric of 03,697 cc was obtained.

The fabric weight dispersion index of the obtained nonwoven fabric was 40.

Example 4 Extruded at 200.9/min, spun using the same equipment as Example 1 except for using a single component spinneret,
It was passed through a rectangular high-speed airflow traction device.

At that time, one side of the filament group was rubbed with a 200 mm long metal rod approximately 5 times above the high-speed airflow traction device, and then passed through the traction device, charged with a rear corona device, and deposited on a moving conveyor. The obtained web was uniform and bulky. The average number of filament crimps is 6/25 wg
It was.

This web was passed through a 2-dorno 4-inch mill to obtain a bulky and uniform long-fiber nonwoven fabric with a thickness of 2 m+11. Bulk density is 0.05g
/CC, and the basis weight dispersion index was 70.

Comparative Example Instead of the rectangular high-speed airflow traction device that pulls the filament group in Example 1, eight round high-speed airflow traction devices with slits of 3 smφ were installed at 10W intervals, and the filament group was divided into eight. After being pulled at a speed of 3200 m/min, the receiving web was placed on a wire mesh and web conveyor equipped with a moving suction device. The obtained web was bulky but non-uniform with no single filament spreadability and clearly myositis. The average number of filaments constituting the web was 7 and 725 crimps.

This web was heat-bonded in the same manner as in Example 1 to obtain a bulky long fiber nonwoven fabric with uniform shininess. The basis weight dispersion index of this nonwoven fabric was 105.

〔Effect of the invention〕

Since the bulky long fiber nonwoven fabric according to the present invention has the above-mentioned structure, it is bulky and has no myositis and has high uniformity. Therefore, it can be usefully used in fields where it is difficult to use conventional long fiber nonwoven fabrics, such as top sheets and nonwoven fabrics for improving drainage or purifying drainage.

[Brief explanation of drawings]

1 and 2 are perspective views showing an example of an apparatus for producing a bulky long fiber nonwoven fabric according to the present invention, and FIG. 3 shows a rectangular high-speed air flow used in the apparatus shown in FIGS. 1 and 2. It is a sectional view showing a jet device of a traction device. 1...Round spinneret, 1'...Spinning nozzle, 2...
・Rectangular air sucker, 3... Corona charging device, 4...
Wire mesh web conveyor, 5.5'...filament group,
6... Long fiber web, 7... Jet device.

Claims (1)

[Claims] 1. A uniform bulky long-fiber nonwoven fabric that is free from streaks and has a basis weight dispersion index of 80 or less, consisting of a plurality of continuous filaments with a number of crimps of 2 to 30/25 mm.