JP2000119946A - Nonwoven fabric of high elongation and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high-elongation nonwoven fabric that is suitable as a simple nonwoven fabric by showing high elongation, particularly in the transverse direction, as a composite nonwoven fabric in combination with a stretchable material and as a back sheet for absorbing articles such as paper diaper and its production. SOLUTION: This nonwoven fabric is prepared by fuse-bonding the curd web comprising thermoplastic synthetic fibers having a filament elongation at break of >=200% so that the fusing units of 2-10 mm2 may distribute separately from each other and the total of the fuse-bonded areas may becomes 5-18% of the web area and the unit weight is 10-50 g/m2 and the elongation at break is >=150% in the transverse direction. Further, this nonwoven fabric is produced so that the orientation of the fibers constituting the web may be >=3 at a ratio of the longitudinal direction to the transverse direction, the unit weight may be 10-50 g/m2, and the fusing units of 2-10 mm2 area may distribute separately from each other and the total fusing area may become 5-18% of the web area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high elongation nonwoven fabric suitable for use as a back sheet for absorbent articles such as diapers, and a method for producing the same.

[0002]

2. Description of the Related Art A nonwoven fabric used in combination with an elastic material used for a back sheet of an absorbent article generally has a deformation following the elongation of the material corresponding to a stress during use,
In other words, although elongation is required, conventional spunbond and dry nonwoven fabrics have a drawback in that the required elongation is insufficient, and thus the movement of the elastic material is stopped, and as a result, the desired function can be imparted to the product. Not showing any serious flaws.

[0003]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and in particular, by exhibiting a high degree of elongation in the transverse direction, as a single nonwoven fabric,
Alternatively, it is another object of the present invention to provide a nonwoven fabric that can easily follow a movement as a composite nonwoven fabric with a stretchable material to be used in combination without impairing the degree of expansion and contraction.

[0004]

As a result of various studies on the above problems, the present inventor has found that a card web made of short fibers of thermoplastic synthetic fiber having specific characteristics is heat-treated under a certain condition, such as an embossed calender. It has been found that the above problem can be solved by performing fusion bonding, and the present invention has been completed.

That is, the first of the present invention is that the single fiber cut elongation is 2
On a card web made of thermoplastic synthetic fibers of 00% or more, the fused units having an area of ² to 10 mm ² are distributed so as to be separated from each other, and the total fused bonding area is 5 to 18% of the web area. %, A non-woven fabric characterized by having a basis weight of 10 to 50 g / m ² and an elongation at break of 150% or more in the transverse direction. The fiber comprises a thermoplastic synthetic fiber having a single fiber cutting elongation of 200% or more, and the degree of orientation of the fiber constituting the web is 3 or more in a length / width ratio, and the basis weight is 10 to 50 g / m.
^2. The heat fusion is performed so that the fusion units having an area of ² to 10 mm ² are distributed on the card web of ^{2 in} a spaced apart manner, and the total fusion bonding area is 5 to 18% of the web area. Characterized by joining, having a transverse elongation of 1
This is a method for producing a nonwoven fabric of 50% or more.

Hereinafter, the present invention will be described specifically. Considering the required properties of the final product, the cut elongation of the single fiber used in the present invention needs to be 200% or more, and preferably 300% or more. By using such a high-stretch single fiber, a nonwoven fabric having a high elongation can be obtained.

[0007] The high-extensibility single fiber used in the present invention must be a thermoplastic fiber having excellent heat-sealing properties such as hot embossing and high-frequency welding. Composite fibers such as those based on polyester or polyester are preferred. In particular, olefin fibers such as polypropylene are preferable because they exhibit relatively high elongation. Further, the fiber is not limited to the conjugate fiber, and may be a single-component fiber such as polypropylene which satisfies high elongation and heat fusing property.

In producing a card web using the above-described single fibers, the arrangement state of the fibers may be unidirectional, semi-random, random or cross-lay.
In particular, a unidirectional, semi-random arrangement is desirable for expressing high elongation in the lateral direction. For example, in the case of a unidirectional card web, the degree of fiber orientation is about 90/10 in a length / width ratio, and in the case of a semi-random web, it is about 75/25, and it is desirable that the degree of freedom in deformation in the horizontal direction is greater. The degree of orientation referred to here is a value obtained by measuring the strength of a warp or a weft by fixing the web in that state by impregnating the resin with the resin, and expressing the result by the numerical value ratio.

[0009] When performing heat fusion bonding such as hot embossing to a card web, the bonding area and the emboss pattern are extremely important factors in order to maximize the transverse elongation while maintaining the strength of the nonwoven fabric. Speaking of embossed patterns, embossed patterns such as rectangular, diamond, or elliptical with their major axis positioned at one-way or at right angles to the fiber axis (vertical) of the semi-random web are arranged in a zigzag pattern. In general, an excellent elongation effect is obtained. Further, in order to obtain the maximum elongation and in consideration of the flexibility, touch, strength and the like of the obtained nonwoven fabric, the bonding area is 18
5% or less is appropriate, and 15% or less 8%.
The above is more preferable. If the fusion bonding area exceeds 18%, it is not preferable in that the required elongation cannot be obtained. On the other hand, if the fusion bonding area is less than 5%, the required strength cannot be obtained, which is not preferable.

For the heat fusion bonding, known heat fusion means usually used for this kind of bonding, such as a hot emboss roller or high frequency fusion, may be used.
To 10 mm ² fusion unit is desirably present in the distribution state of being spaced apart from each other. If the fusion unit is smaller than 2 mm ² , the necessary strength cannot be obtained, which is not preferable. If it is larger than 10 mm ² , the required elongation cannot be obtained, which is not preferable. Here, the fusion unit does not limit its shape.

The basis weight of the nonwoven fabric is from 10 to 50 in view of the application.
g / m ² , and if the transverse elongation at break is 150% or more, it acts almost without hindering the movement of the stretchable material used in combination, and sufficiently functions as a final product. It can be satisfied.

The stretchable material to be used in combination is a nonwoven fabric including its cost, and any type of stretchable nonwoven fabric may be used. Among them, a melt-blown nonwoven fabric is preferred. In this case, the basis weight of the laminate of the present nonwoven fabric and the combined stretchable nonwoven fabric material is 50 to 200.
A laminated sheet having a transverse elongation of 100% or more at g / m ² can be obtained.

The bonding with the stretchable material used in combination with the present nonwoven fabric may be carried out by heat fusion or by using a hot melt adhesive or the like, but the bonding is carried out so that the high elongation of the nonwoven fabric is not hindered. It is important to perform bonding using the latter hot melt adhesive.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Example 1: Sheath-core type thermoplastic composite fiber composed of polypropylene-modified polypropylene (elongation of single fiber: 410%)
Using a 2 denier 38 mm cut staple, a card web of 25 g / mm ^{2 in} semi-random orientation was prepared. The degree of orientation of this web was 79 / vertical to horizontal ratio.
21.

Next, the flow direction (vertical) of the card web
On the other hand, a diamond-shaped fusion unit having a side of 0.6 mm was staggered, and 14 fusion units were arranged in 1 cm ^{2 in a} staggered manner.
Emboss bonding was performed at 20 ° C. and a linear pressure of 30 kg / cm to obtain a nonwoven fabric. The cut elongation of the obtained nonwoven fabric was 64% in length and 220% in width, and showed high elongation in the transverse direction.

When the above nonwoven fabric was bonded to an elastic polyolefin meltblown nonwoven fabric made of an ethylene-octene copolymer using a hot-melt adhesive and used as a back sheet for a pants-type paper diaper, the meltblown nonwoven fabric had sufficient elasticity. A diaper with excellent fit characteristics was obtained.

Comparative Example 1: A sheath-core type thermoplastic composite fiber (polyfilament elongation 57) made of polyester-polypropylene
%) Of 2 denier 38 mm cut staples, and a nonwoven fabric was obtained in the same manner as in Example 1. The cut elongation of this nonwoven fabric was 51% in length and 92% in width. When this nonwoven fabric was used as a back sheet of a pants-type disposable diaper in the same manner as in Example 1, the disposable diaper lacked the fit in which the stretchability of the bonded stretchable meltblown nonwoven fabric was regulated.

Comparative Example 2 The same card web as in Example 1 was used, and the card web was embossed. In this case, an embossing roller having the same embossing pattern and similar arrangement but using a pattern area of 26% of the total surface area (that is, a bonding area of 26%) was used. The cut elongation of the obtained nonwoven fabric was 38% in length and 68% in width, and it was remarkably lacking in flexibility. When this was used for a pants-type paper diaper in the same manner as in the example, the elasticity of the melt blown nonwoven fabric was significantly inhibited, and only a diaper having poor fit and poor texture was obtained.

[0019]

The high elongation non-woven fabric of the present invention has an extremely high elongation in one direction, and therefore, when used in combination with a stretchable material used for absorbent articles such as diapers, the high elongation is easily achieved. Therefore, the functions expected of the final product can be sufficiently satisfied.

Continued on the front page F term (reference) 3B029 BB02 BB07 BC02 BC07 4L041 AA07 BA02 BA05 BA09 BA21 BA49 BC04 BC20 BD03 BD07 BD11 BD20 CA38 DD01 DD05 4L047 AA14 AA27 AB02 AB03 AB10 BA08 CA05 CA12 CA19 CB01 CC04

Claims (3)

[Claims] 1. A card web made of a thermoplastic synthetic fiber having a single fiber cut elongation of 200% or more is applied to an area of 2 to 10 mm.
^{As the two} fused units are in a distributed state separated from each other,
And the total fusion bonding area is 5 to 18 of the web area.
% By heat fusion bonding, and the basis weight is 10 to 5%.
A nonwoven fabric characterized by having a transverse elongation at cut of 150% or more at 0 g / m ² . 2. The nonwoven fabric according to claim 1, wherein the nonwoven fabric has a single-fiber cut elongation of at least 200% of a thermoplastic synthetic fiber which is a core-sheath type or a side-by-side type composite fiber, at least on the surface side thereof. A non-woven fabric characterized in that the component (1) is a heat-fusible conjugate fiber having a lower melting point than other components. 3. A web comprising a thermoplastic synthetic fiber having a breaking elongation of a single fiber of 200% or more, a degree of orientation of a fiber constituting the web being 3 or more in a length / width ratio, and a basis weight of 10 to 50 g / m ^2.
Thermal fusion bonding so that the fusion units having an area of ² to 10 mm ² are in a distribution state separated from each other on the card web, and the total fusion bonding area is 5 to 18% of the web area. A transverse elongation at break of 1
A method for producing a nonwoven fabric which is 50% or more.