JPH0811861B2 - Stretchable nonwoven fabric and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a flexible and highly stretchable nonwoven fabric suitable for applications such as supporters, bandages, and cataplasms, and a method for producing the same.

[Conventional technology]

There have been various methods for producing elastic nonwoven fabrics, and those using thermoplastic polyurethane fibers have been used (Japanese Patent Laid-Open No. 59-1573).
No. 62), which is obtained by heat-bonding highly crimpable polyester fibers with a hot-melt type binder fiber (JP-A-62-177269).
No.) and the like.

[Problems to be Solved by the Invention]

However, non-woven fabrics using polyurethane fibers have the disadvantages of high specific gravity and rubber-like sticky feel, and the disadvantages of using polyester fibers are that the feel is too hard. An object of the present invention is to provide a method for producing a nonwoven fabric which is flexible, has no stickiness and is excellent in elasticity.

[Means for solving the problem]

That is, the first invention of the present application is 70% by weight or more of a polypropylene-based heat-adhesive conjugate fiber having a low temperature web shrinkage of 15% or less and a high temperature web shrinkage of 50% or more, and 30% by weight of other organic fibers. A homogeneous web is made using the following, and a entangled web in which fibers are entangled with each other by injecting a water stream into the web, and then the entangled web in a water-containing state is conveyed in a tension-free state on both front and back surfaces thereof. By blowing hot air of 150 ° C or more alternately and in multiple stages, elastic recovery rate at 30% elongation obtained by causing shrinkage and adhering fibers while floating the entangled web is obtained. 80% in both directions
The elastic nonwoven fabric and the manufacturing method thereof are as described above.

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

The thermoadhesive conjugate fiber thus obtained is used alone or as a web by mixing with other organic fibers. Here, other organic fibers are organic fibers such as cotton, hemp, rayon, polyamide, and polyester, which are not deteriorated by the heat treatment described below, and are intended to improve the feeling of the product, water absorption, etc. Used in. If the content of such other organic fibers in the web exceeds 30% by weight, the bonding points due to the heat-adhesive composite fibers become too small and the strength of the nonwoven fabric decreases, or the shrinkage ratio of the web decreases and the elasticity of the nonwoven fabric decreases. Is not preferable because the result is insufficient. A known method such as a card machine or an airflow type random weber can be used to manufacture the web, and a cross wrapper web may be formed by using a cross wrapper.

Next, high pressure water ejected from a large number of nozzles is sprayed onto the web to cause the fibers to be entangled with each other. As such a method of water entanglement, those disclosed in JP-A-62-223355 or JP-A-59-26561 can be used.

Web that has been subjected to the above-mentioned hydroentanglement process (hereinafter, entangled web)
Is transported to the subsequent heat treatment step in the water-containing state. In the heat treatment step, the entangled web is heated by hot air from both front and back sides while being conveyed without tension. This is specifically described with reference to FIG. 1 which is a schematic view of an example of an apparatus for performing this heat treatment. The entangled web (1) which is sent between a pair of guide nets (2) and (2) 'running at a constant interval is a hot air outlet which is elongated and opened like a slit in the width direction of the web. (3) and (3) 'contact the guide nets (2) and (2)' by hot air alternately blown to the front and back surfaces of the entangled web, and are conveyed while meandering by the frictional force. During this transport the entangled web is dried,
The shrinkage of the heat-adhesive conjugate fiber and the heat-bonding are performed, and the stretchable nonwoven fabric (4) is taken out. Guide net (2),
The interval (2) ′ is 2 to 200 times, preferably 5 to 20 times the thickness of the entangled web.

〔The invention's effect〕

In the present invention, as the main constituent fibers of the non-woven fabric, a heat-adhesive conjugate fiber having a heat shrinkage of 15% or less by heating at 100 ° C. for 5 minutes is used, and heat treatment is performed as a entangled web in a water-containing state, The rapid shrinkage of the web, which is likely to occur during heat treatment, and the uneven density and wrinkles of the non-woven fabric due to the shrinkage, are prevented. Also, the heat-adhesive conjugate fiber is
Since the shrinkage rate of the web by heating at 150 ° C for 5 minutes is 50% or more, and it is subjected to heat treatment while being conveyed in a non-emergency state, the resulting nonwoven fabric has crimped conjugate fibers contacting each other. It has a fused structure and is a highly stretchable non-woven fabric having an elastic recovery rate of 80% or more after being stretched by 30% in both longitudinal and transverse directions. Such non-woven fabrics have 15
For items with a low weight of ~ 300g / m ² , for bandages, paper diaper surface materials, interlining for clothing, etc., and for items with a high weight of 300-1000g / m ² , padding or packing for chairs and beds. It is useful for wood applications.

〔Example〕

The present invention will be described more specifically with reference to Examples and Comparative Examples. The physical property measurement methods used in each example are shown below collectively.

Heat shrinkage of web: Meshoku 1000 made using a card machine
A 25 cm long × 25 cm wide square sample piece was cut from a random web of g / m ² and left for 5 minutes in a dryer at a specified temperature (100 ° C, 150 ° C) sandwiched between kraft paper (25 cm × 25 cm). Cool for 30 minutes at room temperature, measure the area (Scm ² ) and calculate from the following formula. It is represented by the average value of 5 samples.

Thermal shrinkage of web (%) = 100 × (625-S) / 625 Elastic recovery rate of non-woven fabric: Cut a 15 cm long and 2.5 cm wide specimen in the longitudinal or horizontal direction of the non-woven fabric. Using a self-recording tensile tester, gripping interval 10 cm, tensile speed
Elongate by 3cm at 10cm / min and leave for 1 minute, then 10cm / min
Relax at min speed. Read the residual elongation (Amm) from the recording paper when the stress reaches zero during this relaxation process,
It is calculated from the following equation. Both the vertical and horizontal directions are represented by the average value of 5 samples.

Uniformity of non-woven fabric: The smoothness of both front and back surfaces of four 25 cm x 25 cm square sample pieces and the observation of density unevenness under a fluorescent lamp are observed and classified according to the following criteria.

Good: All 4 sheets have no wrinkles and no density spots. Fair: One of the 4 sheets has wrinkles or density spots on the surface. No: 4 pieces have wrinkles or density spots on the surface. There are two or more sheets. Examples 1 to 6 and Comparative Examples 1 to 3 Composite spinning is carried out by combining various types shown in Table 1 with high melting point polypropylene and low melting point propylene-based copolymer or polyethylene, Various composite fibers were obtained. The spinning conditions were the same as described below in each case.

The spinneret has a nozzle hole diameter of 0.6 mm, a number of nozzles of 120, a composite ratio of 1: 1 and a spinning temperature of 280 ° C. on the high melting point side and 240 ° C. on the low melting point side. Roll and 35
Single-filament fineness of 3 by stretching 4.4 times between the second stage seven rolls at ℃
The d / f stretched yarn was made into a tow with a total denier of 12,000, crimped to 12 threads / 25 mm with a stuffed box crimper, and then cut into staple fibers having a fiber length of 65 mm.

Example 1
A random web having a basis weight of 40 g / m ^{2 was used in} Example 4 and Comparative Examples 1 to 3, and a cross-lapper web having a basis weight of 40 g / m ^{2 was used in} Examples 5 and 6.

Next, these webs are transferred to a water jet entanglement device,
30kg / cm ² from many nozzles with hole diameter 0.15mm and pitch 1.0mm
High-pressure water is sprayed, and water entanglement is applied at a transfer rate of 30 m / min to form an entangled web with a water content (water content / fiber weight ratio) of about 110%, and then a heat treatment device as shown in FIG. (Belt spacing 18 mm, length 4.5 m, 35 hot air outlets) was heat-treated at a hot air temperature of 150 ° C. for a residence time of 1 minute 50 seconds to give a nonwoven fabric.

The properties of the heat-adhesive conjugate fibers used in each of the above examples and the properties of the obtained nonwoven fabric are shown in Table 2. FIG. 2 shows the heat shrinkage behavior (web area shrinkage rate) of each of the above heat-adhesive conjugate fibers.

The following is clear from the results shown in Table 2.

In Examples 1 to 6 in which the low temperature web shrinkage is low and the high temperature web shrinkage is large, the elastic recovery rates of the resulting nonwoven fabrics after stretching by 30% are longitudinal and transverse. The direction was 90% or more, and similar results were obtained whether the raw material web was a random web (Examples 1 to 4) or a cross-lapper web.

In Comparative Examples 1 and 2 using the heat-adhesive conjugate fiber having a large low-temperature web shrinkage ratio, the resulting nonwoven fabric is inferior in uniformity, and in Comparative Examples 2 and 3 using the heat-adhesive conjugate fiber having a low high-temperature web shrinkage ratio. The resulting non-woven fabric has a poor elastic recovery rate.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of the heat treatment apparatus used in the example, and FIG. 2 is a graph showing the heat shrinkage behavior of the conjugate fiber used in the example.

Claims (2)

[Claims] 1. A polypropylene-based heat-adhesive composite fiber having a shrinkage rate of 15% or less at a low temperature and a shrinkage rate of 50% or more at a high temperature, and 30% by weight or less of another organic fiber. To make a homogenous web, injecting a water stream into the web to entangle the fibers with each other to form an entangled web, and then convey the entangled web in a water-containing state in a tension-free state while keeping the front and back surfaces at 150 ° C or more. By blowing hot air alternately and in multiple stages, the elastic recovery rate of 30% elongation obtained by causing shrinkage and adhering fibers while floating the entangled web is 80% in both longitudinal and lateral directions. % Or more, a stretchable non-woven fabric. 2. A polypropylene-based thermo-adhesive composite fiber having a shrinkage rate of 15% or less at a low temperature and a shrinkage rate of 50% or more at a high temperature, and 30% by weight of other organic fibers.
A homogeneous web is made using the following, and a entangled web in which fibers are entangled with each other by injecting a water stream into the web, and then the entangled web in a water-containing state is conveyed in a tension-free state on both front and back surfaces thereof. A method for producing a stretchable non-woven fabric, characterized in that hot air of 150 ° C. or higher is blown alternately and in multiple stages to cause shrinkage and adhesion of fibers while allowing the entangled web to move.