JPH02210053A - Bulky nonwoven fabric and body fluid-absorbing article having the same on surface layer - Google Patents

Abstract

PURPOSE:To obtain the title nonwoven fabric having excellent recovery after compression for many hours by arranging a component comprising polybutylene terephthalate and polyethylene terephthalate and a component such as polyethylene in side by side type or sheath-core type and thermally fusing both the components by the latter. CONSTITUTION:(A) A first component comprising 100-70wt.% polybutylene terephthalate-based polymer and 0-30wt.% polyethylene terephthalate-based polymer and (B) a second component comprising a polyethylene-based polymer are subjected to conjugate spinning in such a way that both the components are arranged in a fiber section in side by side type or in sheath-core type of the first component as core and the second component as sheath wherein the centers of the gravity of both the components are not superimposed and the conjugation ratio of the first component and the second component is (70:30)-(40:60), the conjugate yarn is made into web containing >=30wt.% of the conjugate yarn, which is heat-treated and thermally fused by the second component of the conjugate yarn to give the aimed bulky nonwoven fabric.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a bulky nonwoven fabric made of three-dimensionally crimped fibers,
In particular, the present invention relates to a bulky nonwoven fabric that has a large specific volume and good recovery properties after long-term compression, and a body fluid absorbent article using this nonwoven fabric.

(Prior art) It has been known for a long time to use heat-sealable fibers with spiral three-dimensional crimps to obtain bulky nonwoven fabrics. For example, the use of composite fibers of polyethylene and polyethylene terephthalate is particularly It is described in Publication No. 44-8400. Furthermore, an example of a nonwoven fabric using hollow heat-sealable composite fibers for the purpose of improving bulkiness is disclosed in Japanese Patent Application Laid-Open No. 62-299514.
Seen in the publication.

In all of the above techniques, composite Il is used to obtain bulkiness of nonwoven fabrics.
The three-dimensional crimp of the fibers is sufficiently developed, and the low melting point component is thermally melted to bond and integrate the constituent fibers. Since such nonwoven fabrics have particularly good moisture permeability, they can be polymerized with layers made of cotton pulp, superabsorbent polymers, or absorbent paper, etc. to form the surface layer ( (skin contact surfaces).

(Problems to be Solved by the Invention) Before the bulky nonwoven fabric is processed into the above-mentioned articles, it is formed as a nonwoven fabric to develop bulkiness and then stored by being rolled around a core.
It is usually transported. The longer the storage time, the more bulky the fabric becomes, and when actually used, the thickness of the nonwoven fabric may be reduced by about 50% from its initial thickness. Therefore, in order to provide the necessary bulk to the product, the nonwoven fabric had to be thick enough to allow for bends in advance.

Therefore, the specific volume (cm'/g) of the product was smaller than that of the nonwoven fabric at the time of manufacture.

The surface layer of body fluid absorbent articles, which is the main application of bulky nonwoven fabrics, is inconvenient if the water retained in the water absorption layer flows back.To prevent backflow, the first surface layer should be made of hydrophobic fibers. Of course, it is desirable to reduce the fiber density and increase the specific volume as much as possible so that capillary action does not occur within the constituent fibers.

The present invention provides a bulky nonwoven fabric suitable for such uses, and even if the nonwoven fabric is stored in a rolled state for a long time after being formed, the bulk will not decrease much, and the initial bulkiness of the product will be reduced. The feature is that it can also be used in

(Means for Solving the Problems) In order to achieve the above object, the present inventors have developed a composite fiber made of polybutylene terephthalate and polyethylene that exhibits extremely high three-dimensional crimp.

The present invention was achieved by paying attention to the fact that crimp elasticity does not change even after long-term compression.

That is, the first invention of the present invention is.

A component consisting of 100 to 70% by weight of a polybutylene terephthalate polymer and 0 to 30% by weight of a polyethylene terephthalate polymer, and a second component consisting of a polyethylene polymer.
The composite ratio of the first component and the second component is determined by arranging the components in parallel in the fiber cross section or in a core-sheath type with the first component as the core and the second component as the sheath so that the centers of gravity of both components do not overlap at one point. This is a bulky nonwoven fabric containing 30% or more of conjugate fibers with a ratio of 70+30 to 40:60 and thermally fused with a second component of the conjugate fibers.

The first component of the composite fiber serves as a crimped support, and the polybutylene terephthalate polymer may be not only a homopolymer but also a copolymer or a modified composite.
Furthermore, it may be a mixture of polybutylene terephthalate and polyethylene terephthalate, which has good compatibility, but the amount of polybutylene terephthalate must be 70% or more in order to obtain sufficient crimpability and elastic recovery power of the FF composite fiber. This polyethylene phthalate is not limited to a homopolymer, but may also be a copolymer, a modified copolymer, or a mixture thereof.

The second component is the first component for crimp development of the composite fiber! j.

Only polyethylene polymers can achieve this purpose. As the polyethylene polymer, polyethylene, ethylene copolymers, and mixtures thereof can be used. Linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene are used as polyethylene, and low-density polyethylene has a melting point of 120°C.
The following are not preferred because they make fiber formation difficult.

The ethylene copolymer is selected from monovinyl carboxylic acids such as acrylic acid, methacrylic acid, and maleic acid, their esters such as methyl or ethyl, or α-olefins such as vinyl acetate, propylene, butene-1, and octene-1. Resins with good linearity are preferred, however, resins with a melting point of 80° C. or lower are not preferred because they are poorly handled in the manufacturing process.

The composite ratio of the first component and the second component is 70:30 to 40:60
It is.

If the first component is less than 40%, the elastic recovery of the composite fiber is poor;
On the other hand, if it exceeds 70%, the heat fusion strength of the second component becomes insufficient. Further, the composite shape is either a parallel type or a core-sheath type in which the centers of gravity of both components do not coincide.

This is a necessary structure for producing crimp, and a concentric core-sheath type does not produce sufficient three-dimensional crimp in the composite fiber.

The bulky nonwoven fabric of the present invention is produced by mixing the above-mentioned conjugate fibers alone or with other fibers, preferably #8m elastic fibers. When blending, at least 30% of the above composite fibers are used.
Must be included. If the composite fiber contains preferably 50% or more, more preferably 80%, the bulk recovery performance, which is the object of the present invention, can be sufficiently exhibited.

To produce such a nonwoven fabric, fibers may be blended using a conventional method, formed into a web, and then heat treated.

The heat treatment is preferably carried out using a hot air penetrating processing machine at a temperature higher than the melting point of the second component of the composite fiber and 20°C higher than the melting point of the first component.
This is carried out in a lower temperature range than above, and the first component is melted to heat-seal the whole. At the same time, the composite fiber develops three-dimensional crimp, making the nonwoven fabric bulky.

The bulky nonwoven fabric according to the first invention described above is suitably used as a surface layer of a body fluid absorbent article.

For disposable diapers and feminine sanitary products, it is desirable that the surface that comes into contact with the skin (surface layer) is always dry, but in order to do so, the surface layer must have good water permeability so that the water retained in the water absorption layer does not flow back. For this purpose, it is preferable that the surface layer has a bulky property with appropriate elasticity and a structure with as little fiber content as possible to prevent capillarity, that is, a material with a large specific volume.

The bulky nonwoven fabric of the first invention is most suitable for this surface layer.

A second invention of the present invention is a body fluid absorbent article comprising the bulky nonwoven fabric of the first invention as a surface layer and laminated with a water absorbent material layer.

The second invention will be explained using one drawing using the example of a disposable diaper.
A paper diaper consists of a surface layer (1) of a nonwoven fabric, a water-absorbing material layer (2) made of flocculent valves, and a leak-proof layer (3) such as a polyethylene film, which are laminated and integrated. A string and adhesive tape are attached to make it convenient to wear.

It is desirable that the surface layer prevent urine absorbed into the water-absorbing material layer from flowing back (called wet back) as much as possible.The specific volume of the nonwoven fabric used for the surface layer is 80 or more, preferably 100 or more. Good.

(Action of the invention) The bulky nonwoven fabric according to the first invention is made of composite fibers containing polybutylene terephthalate as a main component. # It is made by expressing shrinkage, has high elastic recovery even when using fine composite fibers, and has excellent bulk recovery even after being compressed for a long time.
It is lighter than other non-woven fabrics of the same bulk. The body fluid absorbent article of the second invention using this nonwoven fabric in the surface layer has a good texture with less wet back.

(Example) Composite fibers used in Examples and Comparative Examples were spun as follows.

Polybutylene terephthalate (PBT) as the first component
, polyethylene terephthalate (PET) and polypropylene (PP), and high density polyethylene (HDPE) and ethylene methyl acrylate (EMA) as the second component.
) was used to melt-spun eccentric core-sheath type composite fibers at a composite ratio of 50:50 for one component.

The spinning conditions were a spinneret hole number of 500. The discharge amount is 280 g/min., and the spinning temperature is 270 to 300°C for the first component and 260 to 280°C for the second component.

After spinning, it is stretched 3.6 to 3.8 times in warm water at 80°C.

100-1 after applying mechanical crimp with stuffer box
It was dried at 10° C. and cut into a length of 5]m+s to obtain a staple.

(Examples 1 to 13 and Comparative Examples 1 to 6 of the first invention) The obtained stable composite fibers were mixed alone or with other fibers and made into a web using a roller card, and then processed into a web using a hot air penetrating type thermal processing machine.
Heat treatment was performed at 40° C. for 1 minute to develop crimping of the composite fibers, and at the same time melt the second component, thereby bonding and integrally bonding the constituent fibers together to form a nonwoven fabric with a basis weight of 20 g/m.

First, Table 1 shows the cross-sectional shape of the nonwoven fabric made of composite fiber alone, the cross-sectional shape of the comparative composite fiber, the type of resin of each component, the fineness (denier), the initial specific volume TI (cm3/g) of the nonwoven fabric, and the ratio of the specific volume. Shown below.

The initial specific volume was determined by stacking 10 samples of width and length 10CII x 10CIL, placing a 117 cm2 plastic plate on top, and measuring the thickness of each sample.

Ll (mm) Weight (20g/♂) It is expressed as

The specific volume after compression and release is determined by compressing a similar sample to a thickness of 0.1 μl, leaving it for 7 days, releasing the compression, leaving it for 24 hours, and stacking 10 Ig/c+*2 plastic plates. The thickness of each sheet (L2) was measured by placing it on top of the sheet and expressed as L2 (20g/m).

Valve tissue paper with a basis weight of 2 g/n+" was layered on top to form a water-absorbing material layer. On top of this, the compressed and released nonwoven fabric of the first invention was layered, and 1% physiological saline (surface 100 cc of tension (50 dyne/cra) was poured and absorbed. After 2 minutes, 10 sheets of filter paper (lTh4) were stacked on top of the sample, a load of 35 g/c + *2 was applied from above, and the sample was left for 3 minutes. The amount of weight increase (g) was measured and taken as the amount of wet back.

The results are shown in Table-3.

Next, examples of nonwoven fabrics made by blending composite fibers and other fibers are shown below.
Shown in 2.

Regarding the second invention, an example using the nonwoven fabric of the first invention will be shown.

(Examples 1 to 7 and Comparative Examples 1 to 4 of the second invention) Commercially available bulbs were made into flocculates and compressed to a density of 0.1 g/C11″4 using a stacking press so that the fabric weight was 280 g/m2. .Cut this into a length of 30cm x 40ct.
On top of this (the following is a blank space) (Effects of the invention) As seen in Examples 1 to 13, the nonwoven fabric of the first invention exhibits excellent bulk recovery properties with little decrease in specific volume even after long-term compression. . The body fluid absorbent articles of the second invention using this nonwoven fabric in the surface layer have a wet back amount of 1 g or less, and the comparative examples using conventional nonwoven fabrics have a wet back amount of 2 or more, making them easy to use products. It can be seen that it is.

[Brief explanation of the drawing]

Drawing 1 is a cross-sectional view showing the structure of a paper diaper. In Drawing 0, (1) a surface layer, and (2) a water absorbent material layer. (3) Fusogenic layer.

Claims (2)

[Claims] (1) Polybutylene terephthalate polymer 100-7
0% by weight and polyethylene terephthalate polymer 0-3
A first component consisting of 0% by weight and a second component consisting of a polyethylene polymer are arranged in parallel in the fiber cross section, or the first component is a core and the second component is a sheath, and the centers of gravity of both components do not overlap. The first component and the second component are arranged in a core-sheath shape.
A bulky nonwoven fabric containing 30% or more of conjugate fibers with a composite ratio of components of 70:30 to 40:60 and thermally fused by a second component of the conjugate fibers. (2) A body fluid absorbent article comprising the bulky nonwoven fabric according to claim 1 as a surface layer and laminated with a water absorbent material layer.