JPH0238708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a fiber-bonded nonwoven fabric containing thermally bondable fibers, and particularly provides a method for producing a nonwoven fabric that improves the tensile strength of the nonwoven fabric.

Compared to conventional adhesive-bonded nonwoven fabrics in which fibers are bonded together using a liquid adhesive or the like, fiber-bonded nonwoven fabrics in which heat-adhesive fibers are blended and the fibers are bonded together by heating have various advantages. For example, in adhesive-bonded nonwoven fabrics, the liquid adhesive is mainly
Synthetic resin emulsions are used, but the dispersants and residual monomers contained in these are not preferred in fields such as clothing and food, and the adhesive migrates to the surface due to the drying process that evaporates the aqueous dispersion. There are also quality defects such as delamination and delamination.
In addition, the drying process requires a considerable amount of time, which has disadvantages in terms of manufacturing process and cost.

On the other hand, fiber-bonded nonwoven fabrics are excellent without the above-mentioned defects in terms of quality and manufacturing, but the current situation is that the tensile strength of nonwoven fabrics is not sufficiently high.

The inventors of the present invention investigated various reasons why such a fiber-bonded nonwoven fabric cannot obtain sufficient tensile strength, and as a result, they found the cause and succeeded in improving the tensile strength. In other words, if a fiber-bonded nonwoven fabric obtained from a fiber web containing heat-adhesive fibers is cut into a certain width and subjected to a tensile test using a general tensile strength and elongation tester, the fibers with low elongation will be cut first. , then the fibers with high elongation are cut. It has also been found that the larger the difference in elongation among the single fibers of the constituent fibers, the less sufficient strength can be obtained from the nonwoven fabric, and the smaller the difference in elongation, the more sufficient strength can be obtained.

The present inventors have completed the present invention based on these findings.

The present invention contains 20 to 70% by weight of heat-adhesive fibers and 80 to 70% by weight of heat-adhesive fibers.
In a method for producing a nonwoven fabric in which a fiber web consisting of 30% by weight of non-thermally adhesive fibers is thermally bonded by heat treatment, the difference in elongation in single fibers between the thermally adhesive fibers and the non-thermal adhesive fibers is This is a method for producing non-woven fabric characterized by a content of 25% or less.

The thermal adhesive fiber used in the present invention refers to a thermal adhesive fiber with a low melting point or one that has thermal adhesive properties even at a high melting point, and the non-thermal adhesive fiber refers to a fiber that has no thermal adhesive property at all, or Heat-adhesive fiber used as a blend hardly softens or melts under the temperature treatment conditions that develop heat-adhesive properties. Examples of thermally bondable fibers include fibers made of single or copolymerized synthetic resins such as polyolefin, polyacrylic, polyamide, and polyester, and core-sheath type or side-by-side type composites made of these two components. Fibers and the like can be used alone or in combination. In particular, it is more preferable to use core-sheath type composite fibers because high tensile strength can be obtained.

On the other hand, examples of non-thermally bondable fibers include natural fibers,
There are recycled fibers, semi-synthetic fibers, synthetic fibers, and inorganic fibers, and especially for synthetic fibers, it is possible to combine fibers that hardly soften or melt under the conditions where the heat-adhesive fibers described above exhibit heat-adhesive properties. .

In the present invention, the heat-adhesive fiber is 20 to 70% by weight.
If it is less than 20% by weight, the strength is insufficient.
If it exceeds 70% by weight, the effect of improving strength cannot be obtained.

On the other hand, non-thermally adhesive fibers are fiber webs containing 80 to 30% by weight, and by heat-treating these thermally adhesive fibers, the fibers are thermally bonded.

The present invention is characterized in that the difference in elongation between the heat-adhesive fiber and the non-thermally-adhesive single fiber is within 25%.

If the difference in elongation exceeds 25%, it will not be possible to obtain a sufficient strength improvement effect, so the difference in elongation should be 25%.
% or less, preferably within 15%.

As a heat treatment method, a simple hot air treatment may be used, but a nonwoven fabric with even higher strength can be obtained by performing a heat pressure treatment such as calendering or embossing.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 A fiber web was prepared by blending 50% by weight of 3D/51mm core-sheath polyester fibers with a single fiber elongation of 56% and 50% by weight of 3D/64mm polyester fibers with a single fiber elongation of 47%. A nonwoven fabric (A) of 50 g/m ² was obtained by partially thermal bonding using a hot roll calender with a surface temperature of 182°C. The tensile strength of this nonwoven fabric was 21.2 kg/5 cm, and the elongation was 45%. In addition, as Comparative Example 1, the same conditions as Example 1 were used except that a 3d/64 mm polyester fiber having a single fiber elongation of 89% was used instead of the above polyester fiber having a single fiber elongation of 47%. A nonwoven fabric (B) of 50 g/m ² was obtained.

The tensile strength of this nonwoven fabric was 17.1 kg/5 cm, and the elongation was 42%.

As described above, the tensile strength of Example 1 was approximately 24% higher than that of Comparative Example 1.

Example 2 50% by weight of 3d/51mm core-sheath polyester fibers with a single fiber elongation of 56% and 50% by weight of 1.5d/38mm polyester fibers with a single fiber elongation of 43%
A nonwoven fabric of 50 g/m ² was obtained by partially thermocompressing a fiber web obtained by blending the above and the like with a hot roll calender having a surface temperature of 180°C. The tensile strength (vertical) of this nonwoven fabric is 18.2Kg/5cm, and the elongation is 40%.
It was hot.

Comparative Example 2 was the same as Example 2 except that a 1.5d/38mm polyester fiber with a single fiber elongation of 20% was used instead of the above polyester fiber with a single fiber elongation of 43%. A nonwoven fabric of 50 g/m ² was obtained under these conditions.

The tensile strength of this nonwoven fabric was 14.8 kg/5 cm, and the elongation was 26%.

Thus, compared to Comparative Example 2, the tensile strength of Example 2 was 23% higher.

In this way, the present invention is a fiber-bonded nonwoven fabric that has conventionally been unable to fully demonstrate its strength, but by the present invention, the strength characteristics of the fibers can be fully demonstrated, and the characteristics have been improved. This is an extremely effective method for producing nonwoven fabrics that allows for various combinations of two or more different types of fibers.

Claims (1)

[Claims] 1 20-70% by weight of thermal adhesive fibers and 80-30% by weight
A method for producing a nonwoven fabric in which a fiber web consisting of non-thermally adhesive fibers is thermally bonded by heat treatment, in which the difference in elongation in single fibers between the thermally adhesive fibers and the non-thermal adhesive fibers is within 25%. A method for producing a nonwoven fabric characterized by the following.