JPH02229255A - Production of nonwoven fabric with uneven surface - Google Patents

Abstract

PURPOSE:To obtain the nonwoven fabric capable of blocking flow of high- viscosity fluid while excellent in permeability, thus useful for paper diapers, etc., by forming unevennesses on a fibrous web by specific means followed by heat fusing of the thermoplastic fiber contained in the web. CONSTITUTION:A fibrous web 2 containing thermoplastic fiber is brought between air-permeable conveyor belts 41 one or both of the surfaces of which have unevennesses, and during carrying said web 2 sandwiched between the conveyor belts, air is blown on the surface of said web 2 to force said web to follow the recesses of the conveyor belts 41 to effect formation of unevennesses on the web 2 followed by heating the web 2 to effect fusing of the thermoplastic fiber, thus obtaining the objective nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field in Icheon] The present invention provides a method for producing a nonwoven fabric having unevenness. More specifically, the present invention relates to a method for producing a nonwoven fabric used as a surface material for sanitary products such as disposable diapers and sanitary napkins.

[Conventional technology]

One of the challenges of sanitary products such as disposable diapers and sanitary napkins is to suppress or prevent leakage of body fluids such as urine, soft stools, and menstrual blood from the sanitary products. To this end, each component of sanitary products, such as the surface material, absorbent material, back material, etc., has been designed to suppress or prevent leakage of bodily fluids.

In general, nonwoven fabrics are often used as surface materials, and these nonwoven fabrics are often made of hydrophilic thermoplastic fibers in order to improve absorbency of body fluids. Also,
In order to prevent seepage and leakage of body fluids, attempts have been made to make the side or surrounding portions of nonwoven fabrics, which are surface materials of sanitary products, hydrophobic.

On the other hand, high viscosity body fluids such as loose stools and highly viscous menstrual blood have poor i3 transitivity with normal non-woven fabrics, and flow over the surface of the non-woven fabric before being absorbed by the internal absorbent material, staining clothing and sometimes even skin. It causes a rash and discomfort.

Conventional countermeasures against these problems include, for example, a method of perforating the nonwoven fabric with pins, needles, etc., and a method of entangling the web with high-speed water jets to form a perforated or mesh shape (Japanese Patent Publication No. 6, 2-6).
2175, 62-28219 t8)
In addition, methods have been proposed such as reducing the basis weight of the nonwoven fabric or increasing the distance between fibers using large denier fibers.

[Problem to be solved by the invention]

However, each of the above methods includes many problems. That is, the method of perforating the nonwoven fabric with a bottle, needle, etc. produces protrusions on the surface of the nonwoven fabric, which is unpleasant to the touch.
If bottles, needles, etc. are damaged during the manufacturing process, there is a risk that broken pieces may be mixed into sanitary products. In addition, the method of entangling the web with high-speed water jets tends to cause fluffing of the nonwoven fabric. Another problem is that the processing speed cannot be increased.

In addition, the method of reducing the basis weight of nonwoven fabrics does not provide the strength required as a surface material, and large denier fibers have the problem of having a rough and hard texture as a surface material.
That is, none of the above-mentioned conventional methods can be said to be sufficient as a method for producing a surface material with excellent permeability.

Accordingly, an object of the present invention is to provide a method for producing a nonwoven fabric that can prevent the flow of a highly viscous liquid and that can produce at high speed a nonwoven fabric that has irregularities and has excellent permeability.

[Means for solving assignments]

The present inventors have conducted various studies on methods for manufacturing nonwoven fabrics that can prevent the flow of highly viscous liquids and have a form with excellent permeability. After forming irregularities on an Ia fiber web by a specific means, the fiber web The thermoplastic fibers contained in
The present inventors have found that it is possible to provide a method for manufacturing a nonwoven fabric with unevenness that solves the problems mentioned above by thermally fusing the fabric.

That is, the present invention was made based on the findings in L.
A fibrous web containing thermoplastic fibers is passed through a pair of breathable conveyors having irregularities on at least one side, and while the fibrous web is being conveyed with the fibrous web sandwiched between them, air is injected onto the surface of the fibrous web to improve the air permeability. The axial fiber web is made to follow the concave portion of a conveyor to form irregularities on the fiber web, and then the fiber web is heated and the thermoplastic fibers described in (1) are fused to form a nonwoven fabric having irregularities. The present invention provides a method for manufacturing nonwoven fabric.

[Effect]

According to the present invention, a fibrous web containing thermoplastic fibers is supported by a pair of air-permeable conveyors having irregularities on at least one side, and air is injected onto the surface of the fibrous web to form irregularities on the fibrous web. By heating, the thermoplastic fibers are fused while retaining the unevenness to form a nonwoven fabric having the unevenness.

〔Example〕

The present invention will be explained below based on the embodiments shown in FIGS. 1 to 3. In the drawings, FIG. 1 is a perspective view showing a nonwoven fabric manufacturing apparatus that can be suitably used when carrying out the method of the present invention, and FIG. 2 is a plan view showing an enlarged part of a breathable conveyor having unevenness. , FIG. 3 is a side view showing the ventilation conveyor shown in FIG. 2. As shown in FIG. 1, the nonwoven fabric manufacturing apparatus used in carrying out the method of the present invention includes a supply section 1 for supplying fibers containing thermoplastic fibers, and a fiber web 2 from which the fibers supplied by the supply section 1 are fed. a card machine 3 forming a card machine 3;
An unevenness forming section 4 receives the fiber web 2 formed in the fibrous web 2 and forms unevenness on the fiber web 2; A heat treatment section 5 that heats and fuses to form a nonwoven fabric 6 having unevenness, and a winding section 7 that winds up the nonwoven fabric 6 that has unevenness formed in the heat treatment section 5.
It is composed of:

The unevenness forming section 4 is provided with a pair of breathable conveyors 41 and 42 on the upper and lower sides for supporting and conveying the fiber web 2. The breathable conveyor 41 disposed on the lower side has the unevenness forming part 4
It is an endless conveyor for conveyance extending from the heat treatment section 5 on the downstream side, and is formed in a mesh shape as shown in FIGS. 2 and 3. It is preferable that the air permeable conveyor 41 has irregularities formed on its surface as shown in FIG. 3, and the height difference h thereof is set to 3 to 8 u. Height difference h is 3++
If it is less than m, as described below, it is difficult to form irregularities in the fiber web 2, or to form perforations in combination with irregularities, and conversely, 31)
If it exceeds 1, the fibrous web 2 after forming the unevenness will be difficult to peel off from the air permeable conveyor 41, which is not preferable. Furthermore, it is preferable that the number of protrusions is set to 10 to 25 pieces/in. If the number of protrusions is less than 10 pieces/1n2, the structural fibers are likely to be blown away by the jet air flow, If it exceeds ``, it becomes difficult to form unevenness, which is not preferable.

On the other hand, the ventilation conveyor 42 disposed on the upper side has a capacity of 3 to 1
An endless conveyor formed into a net shape of 5 mesh and substantially flat so as to be able to press the fibrous web 2 against the lower air-permeable conveyor 41 and sandwich the fibrous web 2;
It is supported in rotation by a roll of books.

Further, the unevenness forming part 4 is formed by a pair of breathable conveyors 4l, 4.
An air injection device 43 is provided which injects air from above onto the fibrous web 2 supported by the fibrous web 2 so that the fibrous web 2 enters and follows the surface recess of the lower air permeable conveyor 4l. The air injection device 43 includes an injection duct 43A inserted from the side into the rotating interior of the upper ventilation conveyor 42, and an injection duct 43A inserted from the side into the rotational interior of the lower ventilation conveyor 41. and a recovery duct 43B, and a blower 43G.
Air is passed through the air-permeable conveyor 42 from the injection duct 43A, and air is injected onto the entire surface of the fiber web 2 pressed by the air-permeable conveyor 42, thereby forming unevenness in the fiber web 2 on the uneven surface of the air-permeable conveyor 4l. That's what I do. The airflow that has passed through the fibrous web 2 and the lower ventilation conveyor 4l is returned to the blower 43C via a collection duct 43B. Therefore, the air volume injected by the blower 43C is 2 for 1 m of the running distance of the fiber web 2.
0-200rrl/plow in. It is preferable to set it to . 2 O n? /sin. If it is less than 20 O, it is difficult to form irregularities or perforations along with the irregularities.
n? /win. If it exceeds this, the fiber web 2 will be disturbed, and the energy load on the blower 43C will become excessive, which tends to be uneconomical. In addition, in order to minimize the energy loss of the jet air flow, the air-permeable conveyor 4 should be
Preferably, the injection is from an internal rotational position close to 3B. Further, the shape of the injection port may be formed by providing a large number of orifice-like pores, but as shown in FIG. 1, a slit-like shape is preferable because it can reduce energy loss.

When heat-sealing thermoplastic fibers, it is preferable to fuse heat-fusible fibers with a core-sheath structure as the thermoplastic fibers with hot air in order to form irregularities or perforations in combination with the irregularities.

The thermoplastic fibers used in carrying out the method of the present invention as described above include polyolefins such as polypropylene and polyethylene, polyesters, and nylon 6.
Examples include polyamide-based fibers such as nylon 66, polyacrylonitrile-based fibers, and sheath-core type and side-by-side type composite fibers made of two or more of these types. Further, the content of thermoplastic fibers in the fiber wafer 2 formed by the card 83 is preferably 30% or more. If it is less than 30%, it may be difficult to obtain a nonwoven fabric strength that does not pose any practical problems when forming irregularities or perforations in combination with irregularities on the fibrous web 2.

Since the uneven nonwoven fabric obtained in the above example contains thermoplastic fibers, it is easily heat-fused and does not easily shed fuzz, and is suitable for practical use as a nonwoven fabric in terms of strength, texture, workability, etc. There is no L problem and it can be preferably used as a surface material for sanitary products.

In addition, since the heat treatment section 5 processes with heated air, force-specific heat rolls, etc., the surfactant applied during the fiber manufacturing process is not easily removed, and there is no need to newly apply a surfactant during the nonwoven fabric manufacturing process. .

The nonwoven fabric obtained in this example had irregularities as described above.
Or, since it has irregularities and perforations, it can further improve the permeability of high viscous liquids, and by forming perforations in the recesses, the high viscosity liquid can be temporarily held in the recesses, improving the fluidity of high viscous liquids. The permeability to the nonwoven fabric can be further improved by lowering the permeability to the nonwoven fabric.

Next, the method of the present invention will be explained in more detail based on the following examples.

Examples 1 to 3 In this example, a fiber web 2 with a fabric weight of 27 g/m was formed using a thermoplastic fiber (core: polyester, sheath: polyethylene) of 3 denier and 38 threads using a general-purpose card machine L.
7. As shown in Table 1, air is injected at a flow rate of 50 m/min/'m into the ventilated conveyor 4L on the lower side where the unevenness is changed, and then the heat is The plastic fibers were fused together and wound up using Ion/win. The obtained nonwoven fabric was evaluated for strength and i3 transitivity shown in Table 1, and the results shown in Table 1 were obtained. For the evaluation of permeable bamboo, we used artificial soft stool (moisture content 97%) as a highly viscous liquid, placed an absorbent material used in commercially available disposable diapers under the non-woven fabric, placed it on a 45" inclined plate, and 3 g of artificial soft stool was dropped, and the distance it flowed down the surface of the nonwoven fabric was measured. In Table 1, CD represents the direction perpendicular to the mechanical flow.

In the comparative example, the fibrous web 2 formed by the card if was directly passed through the air-transmitting conveyors 41 to 42) to the heat treatment section 5 to obtain a nonwoven fabric, and evaluated by the same method as in Examples 1 to 3. The results are shown in Table 1.

According to the results shown in Table 1, it can be seen that Examples 1 to 3 are superior to Comparative Example 1 in permeability to soft human stool, and are also superior in overall evaluation that takes strength into consideration.

Table 1 (Note 1) 0: Strength with no problems in actual production △; Strength with some concerns in actual production ×: Strength in practical use for the former 2L support}: Strength as described in the book title (Note 2) ○: Performance and workability △: Slightly lacking in performance or vigor ×: Problems in performance or vigor [Effects of the Invention] According to the method for producing a nonwoven fabric with unevenness of the present invention, the flow of a highly viscous liquid It is possible to produce at high speed a nonwoven fabric having irregularities that can prevent this and have excellent permeability.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a nonwoven fabric manufacturing apparatus that can be suitably used when carrying out the method of the present invention, and FIG. 2 is an enlarged plan view showing a part of an air permeable conveyor having unevenness.
FIG. 3 is a side view of the ventilation conveyor shown in FIG. 2. 2; Fiber web 4: Irregularity forming section 5; Heat treatment section 6; Nonwoven fabric 41; Air permeable conveyor 42 having unevenness; Air permeable conveyor Fig. 1

Claims (2)

[Claims] (1) A fibrous web containing thermoplastic fibers is passed through a pair of air-permeable conveyors that have irregularities on at least one side, and while the fibrous web is being conveyed with the fibrous web sandwiched between them, air is injected onto the surface of the fibrous web. The fibrous web is made to follow the concave portions of the breathable conveyor to form irregularities on the fibrous web, and then the fibrous web is heated and the thermoplastic fibers are fused to form a nonwoven fabric having irregularities. A method for producing a nonwoven fabric. (2) The method for manufacturing a nonwoven fabric according to claim (1), wherein holes are formed in the recesses.