JPH01221558A - Stretchable nonwoven cloth and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject soft nonwoven cloth free from tacky feeling, by forming a web from a specific polypropylene-type heat-weldable mixed fiber or its mixture with other organic fiber, interlocking the fibers with a water jet and heat-treating the product in a specific state. CONSTITUTION:A polypropylene-type heat-weldable mixed fiber used as a raw material of the objective cloth is characterized to give a web containing >=70wt.% of the mixed fiber and exhibiting a thermal shrinkage of <=15% by heating at 100 deg.C for 5min and of >=50% by heating at 150 deg.C for 5min. A web is produced by mixing >=70wt.% of said mixed fiber with <=30wt.% of other organic fiber and is converted to an interlocked web by applying a water jet. The water-containing interlocked web 1 is introduced between a pair of the guide nets 2, 2' and hot air of >=150 deg.C is alternately blasted against the front and back surfaces of the interlocked web from hot-air blasting nozzles 3, 3' having slit openings. The interlocked web is shrunk under flotation to effect the bonding of the fibers with each other and obtain a stretchable nonwoven cloth 4 having a 30% elongation elastic recovery of >=80% in both longitudinal and transversal directions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a flexible and highly stretchable nonwoven fabric suitable for uses such as Supporter-1 bandages and poultice base fabrics, and a method for producing the same.

[Conventional technology]

There have been various manufacturing methods for stretchable nonwoven fabrics, including those using thermoplastic polyurethane fibers (Japanese Patent Laid-Open No. 59-15
No. 7362), highly crimpable polyester fibers thermally bonded with hot-melt binder fibers (JP-A No. 62-
177269) and the like.

[Problem to be solved by the invention]

However, nonwoven fabrics using polyurethane fibers have drawbacks such as high specific gravity and a flat, rubber-like feel, while polyester fibers have the drawback of being too hard.

The present invention provides a method for producing a nonwoven fabric that is flexible, does not have a sticky feeling, and has excellent stretchability.

[Means to solve the problem]

That is, the first invention of the present application is a polypropylene-based thermoadhesive composite fiber having a low-temperature web shrinkage rate of 15% or less and a high-temperature web shrinkage rate of 50% or more, and 70% by weight or more, and other organic fibers of 30% by weight. A homogeneous web is produced using a leeward direction, a water jet is jetted onto the web to form an entangled web in which the fibers are intertwined with each other, and then the front and back sides of the entangled web in a water-containing state are conveyed in a non-tensioned state. By blowing hot air of 150°C or higher alternately and in multiple stages, the entangled web is allowed to move while causing shrinkage and mutual adhesion of the fibers.The elastic recovery rate at 30% elongation is A stretchable nonwoven fabric having a stretchability of 80% or more in both the transverse directions and a method for producing the same.

In the present invention, the polypropylene thermoadhesive composite fiber used as the main component of the nonwoven fabric is made of two types of polypropylene resins with different melting points in parallel, or with an eccentric sheath-core so that the resin with a low melting point is used as the sheath component. The heat shrinkage rate of a web containing 70% by weight or more of composite fibers, which is composite fibers arranged in a mold and spun, is 15 when heated at 100'C for 5 minutes.
% or less, and 50% or more when heated at 150° C. for 5 minutes. A crystalline polypropylene (homopolymer) having an MFR of 2 to 7o, preferably a propylene homopolymer having a Q value of 5 or less, which is an index of molecular weight distribution, is used as a high melting point component of such a heat-adhesive composite fiber, and a low melting point component is used. A binary or ternary copolymer containing propylene as the main component and other α-olefins such as ethylene and butene-1 as a copolymerization component, preferably having a melting point 15°C or more lower than the high melting point component. Copolymers are used. By selecting/combining these two components and selecting the spinning/drawing conditions, the heat shrinkage rate of the web of heat-adhesive conjugate fibers can be set to a desired value. Further, it is desirable that the heat-adhesive conjugate fibers be mechanically crimped in order to facilitate the production of the web described below.

The thermoadhesive conjugate fiber thus obtained is made into a web either alone or mixed with other organic fibers.

Here, other organic fibers refer to organic fibers such as cotton, linen, rayon, polyamide, and polyester that do not change in quality through heat treatment described below, and are used for the purpose of improving the texture, water absorption, etc. of products. be done. If the content of such other organic fibers in the web exceeds 30% by weight, the bonding points of the heat-adhesive composite fibers will be too few and the strength of the cine woven fabric will decrease, and the shrinkage rate of the web will decrease, resulting in a non-woven fabric. This is not preferable because it results in insufficient elasticity. A known method such as a card machine or an air flow random univer can be used to produce the web, and a crosslapper web may also be produced using a crosslapper.

Next, high aqua regia is sprayed onto the web from a number of nozzles to cause the fibers to become entangled with each other.

A method of such hydroentanglement is disclosed in Japanese Patent Application Laid-Open No. 62-22
3355 or Japanese Patent Laid-Open No. 59-26561 can be used.

The web that has undergone the hydroentanglement treatment (hereinafter referred to as an entangled web) is transported to the subsequent heat treatment step while still containing water. In the heat treatment process, the entangled web is heated by hot air on both the front and back surfaces while being conveyed without tension. A detailed explanation will be given with reference to FIG. 1, which is a schematic diagram of an example of an apparatus for performing this heat treatment. A pair of guide nets (2) running at a constant interval, the tangled web (1) in a water-containing state fed between (2γ) has a hot air outlet opening in the shape of a long slit in the width direction of the web. (3), (3)' The guide net (2
), <2Y and is conveyed in a meandering manner due to the frictional force.

During this conveyance, the entangled web is dried, the heat-adhesive conjugate fibers undergo shrinkage and heat bonding, and are taken out as a stretchable nonwoven fabric (4). Guide net (2J, (Zl' spacing is 2 to 200 times the thickness of the entangled web, preferably 5 to
20 times as large is used.

〔Effect of the invention〕

In the present invention, heat-adhesive conjugate fibers are used as the main constituent fibers of the nonwoven fabric, and the heat shrinkage rate of the web is 15% or less when heated at 100°C for 5 minutes, and heat treatment is performed as an entangled web in a water-containing state. Rapid shrinkage of the web that occurs during heat treatment and the resulting density unevenness and wrinkles in the nonwoven fabric are prevented. In addition, the thermal adhesive composite fiber has a web shrinkage rate of 50% when heated at 150°C for 5 minutes.
As above, and since the nonwoven fabric is heat-treated while being conveyed without tension, the resulting nonwoven fabric has a structure in which sufficiently crimped composite fibers are fused to each other at the contact points, and 30% in both the vertical and horizontal directions. The result is a highly stretchable nonwoven fabric with an elastic recovery rate of 80% or more after stretching. Such non-woven fabrics have a low basis weight of 15 to 30,097 m" and are used for applications such as bandages, surface materials for paper diapers, interlining for clothing, etc.
00~1000 j! /rrl high basis weight is useful for filling chairs and beds or as a backing material for packaging.

〔Example〕

The present invention will be explained in more detail with reference to Examples and Comparative Examples. The physical property measurement methods used on each side are summarized below.

Heat shrinkage rate of web: Fabric weight 100 made using a guard machine
G/I's random web 25cm long x 25cm wide
Cut out a square sample piece from kraft paper (25cII).
LX 25m) at a specified temperature (100℃
℃) for 5 minutes, then cooled at room temperature for 30 minutes, and the area (Scrl'') was measured and calculated using the following formula. It is expressed as the average value of 5 samples.

Heat shrinkage rate of web (g)=I00X(625-8)/6
25 Elastic recovery rate of non-woven fabric: Cut a sample piece of 15 cm long and 2.5 cm wide in the vertical or horizontal direction of the non-woven fabric.
It was stretched by 3 cIL at 0 cIIL and a tensile rate of 10 cIrL/m, left as it was for 1 minute, and then relaxed at a rate of 10α/M. The residual elongation (Am) at the time when the stress becomes zero during this relaxation process is read from the recording paper and calculated using the following formula. Both vertical and horizontal values are expressed as the average value of 5 samples.

Uniformity of nonwoven fabric: Observe the smoothness of both the front and back surfaces of four 25 cm x 25 cm square sample pieces, and observe the density irregularities by fluoroscopy under a fluorescent lamp, and classify them according to the following criteria.

Good: All 4 sheets have no wrinkles or density spots on the surface. Acceptable: 1 of the 4 sheets has wrinkles or density spots on the surface. Not acceptable: 4 sheets have wrinkles or density spots on the surface. Examples 1 to 6, Comparative Examples 1 to 3 Composite spinning of a combination of various high melting point polypropylenes and low melting point propylene copolymers or polyethylene shown in Table 1, Various composite fibers were obtained. The spinning conditions were the same as described below in both cases.

The spinneret has a nozzle hole diameter of 0.6 m and 120 nozzles.
The composite ratio was 1:1, the spinning temperature was 280'C on the high melting point side and 240'C on the low melting point side. 4.4
After drawing the yarn to double its original size and converging it into a tow with a total denier of 12,000, it was crimped with 12 threads of 725B using a stuffing box crimper.
The fibers were cut into fiber lengths of 65 mm to obtain staple fibers.

Examples 1 to 4 The above staple fibers were passed through a carding machine.
In Comparative Examples 1 to 3, a random web with a basis weight of 40 fi/trl was used, and in Example 5.6, a basis weight of 4oy/r was used.
r? It was made into a cross wrapper web.

These webs are then transferred to a water-jet entangling device, where 3
Spray high-pressure water at 9/cit on 0, transfer speed 30m/
Hydroentanglement was applied at 100 m to form an entangled web with a moisture content (moisture weight/fiber weight ratio) of approximately 110%, followed by a heat treatment apparatus as shown in Fig. 1 (belt spacing: 18, depth: 4.5 m).
A nonwoven fabric was obtained by heat treatment using a hot air outlet (35 hot air outlets) at a temperature of 150° C. and a residence time of 1 minute and 50 seconds.

Table 2 shows the properties of the heat-adhesive conjugate fibers used on each side and the properties of the obtained nonwoven fabric. Further, the heat shrinkage behavior (web area shrinkage rate) of each of the above heat-adhesive conjugate fibers is shown in FIG.

Chapter 1 Table The following becomes clear from the results shown in Table 2.

In Examples 1 to 6, in which polypropylene thermoadhesive composite fibers having a small low-temperature web shrinkage rate and a large high-temperature web shrinkage rate were used, the elastic recovery rates after 30% elongation of the obtained nonwoven fabrics were as follows: 90% or more in both directions, even if the raw material web is a random web (Examples 1 to 4),
Similar results were obtained for cross-wrapper webs.

In Comparative Example 1.2 using heat-adhesive conjugate fibers with a high low-temperature web shrinkage rate, the resulting nonwoven fabric was poor in uniformity, and in Comparative Example 2 using heat-adhesive conjugate fibers with a low high-temperature web shrinkage rate.
．． The nonwoven fabric obtained in Sample No. 3 had an inferior elastic recovery rate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram of the heat treatment apparatus used in the examples, and FIG. 2 is a graph showing the thermal shrinkage behavior of the composite fibers used in the examples. Amendment to the above second proceedings

Claims (2)

[Claims] (1) 70% by weight or more of polypropylene-based thermoadhesive composite fibers with a low-temperature web shrinkage rate of 15% or less and a high-temperature web shrinkage rate of 50% or more, and 30% by weight of other organic fibers.
A homogeneous web is made using the following, a water jet is jetted onto the web to form an entangled web in which the fibers are entangled with each other, then an entangled web in a water-containing state is made, and then the entangled web in a water-containing state is made into an unstrained web. 30% elongation achieved by blowing hot air of 150°C or higher alternately and in multiple stages on both the front and back sides of the web while transporting it, causing shrinkage and mutual adhesion of fibers while allowing the entangled web to move freely. A stretchable nonwoven fabric having an elastic recovery rate of 80% or more in both the longitudinal and transverse directions. (2) Using 70% by weight or more of polypropylene-based heat-adhesive composite fibers with a low-temperature web shrinkage rate of 15% or less and a high-temperature web shrinkage rate of 50% or more, and 30% by weight or less of other organic fibers. A homogeneous web is made, a water jet is jetted onto the web to form an entangled web in which the fibers are entangled with each other, and then the front and back surfaces of the entangled web are heated at 150°C or higher while conveying the water-containing entangled web in a non-tensioned state. A method for producing a stretchable nonwoven fabric, characterized by blowing hot air alternately and in multiple stages to cause shrinkage and mutual adhesion of fibers while allowing entangled webs to move freely.