JP2716169B2 - Heat-fusible composite fiber - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a heat-fusible conjugate fiber, and more particularly, to a heat-sealing conjugate fiber suitable for obtaining a nonwoven fabric having a desired bulkiness and a high bonding strength. Conjugated fiber.

[Background Art] As is well known, a nonwoven fabric is manufactured by hot-air fusion of a sheath-core type heat-fusible conjugate fiber in which a plurality of fiber components having different melting points are arranged in a sheath-core shape. The properties required of the nonwoven fabric obtained by hot-air fusion of the heat-fusible conjugate fibers include high fusion strength, bulkiness, and good texture. In particular, regarding the adhesive strength, for example, when used for disposable diapers, further improvement in performance is desired in order to prevent diaper breakage during attachment / detachment, and a nonwoven fabric having high adhesive strength is manufactured. The appearance of the resulting heat-fusible conjugate fiber has been desired.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to provide a heat-fusible conjugate fiber suitable for obtaining a nonwoven fabric having desired bulkiness and high fusion strength.

Means for Solving the Problems The present invention has been made to achieve the above-mentioned object, and has a high melting point component and a low melting point component, one of which is a sheath component and the other is a core component. In the heat-fusible conjugate fiber obtained by melt conjugate spinning, the high melting point component is made of polypropylene, and the melting heat of the low-temperature melting portion of this polypropylene is ΔH ₁ , and the melting heat of the high-temperature melting portion is ΔH _2. A sheath-core type heat-fusible conjugate fiber characterized in that the calorific value ratio ΔH ₁ / ΔH ₂ is 0.35 or less and the heat shrinkage at 130 ° C. of the single yarn is 3.0% or less.

 Hereinafter, the present invention will be described in detail.

The sheath-core type heat-fusible conjugate fiber that is the object of the present invention is obtained by spinning a high-melting component and a low-melting component with one of the sheath component and the other as the core component by melt-spinning. . There are two types of sheath-core heat-fusible conjugate fibers,
One is a concentric type in which a core component and a sheath component are concentrically arranged, and the other is an eccentric type in which the center of the core component does not coincide with the center of the composite fiber and is eccentric. Are also included in the conjugate fiber of the present invention.

In the heat-fusible conjugate fiber of the present invention, as the low-melting point component, polyethylene such as high-density polyethylene is preferably used. be able to. On the other hand, the high melting point component is limited to polypropylene.
As this polypropylene, it is preferable to use crystalline polypropylene, but other polypropylene, for example, a copolymer in which ethylene or the like is partially added can also be used. Various stabilizers, fillers, pigments and the like usually used for polyolefin fibers can be added to the low melting point component and the high melting point component to the extent that the object of the present invention is not impaired.

In the present invention, this polypropylene has a heat of fusion of a low-temperature melting portion of ΔH ₁ and a heat of fusion of a high-temperature melting portion of ΔH _2.
It is an essential condition that the heat of fusion ratio ΔH ₁ / ΔH ₂ is 0.35 or less. The heat of fusion ratio ΔH ₁ / ΔH ₂ can be determined by performing differential scanning calorimetry (hereinafter referred to as DSC) on the conjugate fiber. The details are as follows. In other words, according to the method of JIS K 7122, a sample of a composite fiber containing polypropylene as a high melting point component
5 mg is heated at a rate of 10 ° C./min in a nitrogen atmosphere to draw a DSC curve. In the composite fiber of the present invention, as DSC curve polypropylene shown in FIG. 2, two peaks, namely a peak of the peak P ₁ and the high-temperature melting portions of the low-melting partial
It has a P _2.

Next, the area of the hatched portion S ₁ of the peak P ₁ of the low-temperature melting portion and the area of the hatched portion S ₂ of the peak P ₂ of the high-temperature melting portion were obtained, and from each area, the heat of fusion ΔH ₁ of the low-temperature melting portion of the polypropylene was calculated. The heat of fusion ΔH _{2 of the} portion is determined.

Finally, the heat of fusion ratio ΔH ₁ / ΔH ₂ is determined from the _two heats of fusion ΔH ₁ and ΔH ₂ determined above.

As described above, in the composite fiber of the present invention, it is an essential condition that the heat of fusion ratio ΔH ₁ / ΔH ₂ is 0.35 or less. The reason is that if this value is less than 0.35, a nonwoven fabric having high fusing strength cannot be obtained while maintaining the desired bulkiness. Note that composite fibers in which the DSC curve of polypropylene shows only one peak are excluded.

Further, in the composite fiber of the present invention, it is an essential condition that the heat shrinkage of the single yarn at 130 ° C. is 3.0% or less. The reason is that if this value exceeds 3.0%, a nonwoven fabric having high fusing strength while maintaining the desired bulkiness cannot be obtained.

[Examples] Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 A high-density polyethylene having a low melting point component (J310, MI manufactured by Asahi Kasei Co., Ltd.) was used by using a composite fiber spinning apparatus having two single-screw extruders and a nozzle having a hole diameter of 0.4 mm and a number of holes of 500.
= 20) as a sheath component, and high-melting-point component crystalline polypropylene (S115M manufactured by Ube Industries, Ltd., MI = 15) as a core component, and spun at a spinning temperature of 240 ° C and a take-up speed of 700 m / min. A sheath-core composite fiber having a single yarn denier of 8.0 de was obtained. The sheath component and the core component are arranged concentrically, and the cross-sectional area ratio is 1: 1.

This multifilament is drawn at a draw ratio of 5.0 with a staple fiber prototype, oiling, crimping,
After drying, heat-treated with hot air of 110 ° C for 15 minutes, and cut, single yarn denier 2de, cut length 51mm, number of crimps 18 /
inch and a crimp rate of 13% were obtained. For this conjugate fiber, the heat of fusion ΔH ₁ of the low-temperature melting portion of the crystalline polypropylene and the heat of fusion ΔH ₂ of the high-temperature melting portion of the crystalline polypropylene were determined by the above-described JI.
It was 6.3 KJ / Kg and 50.4 KJ / Kg, respectively, as shown in Table 1 when determined based on the method of SK 7122, and the heat of fusion ratio ΔH ₁ / ΔH ₂ was included in the limited range (0.35 or less) of the present invention. Be
The heat shrinkage at 130 ° C. of the single yarn was 2.3%, which was included in the limited range (3.0% or less) of the present invention.

The staple fiber was passed through a 350 mm-width sample card machine three times to produce a uniform web having a basis weight of 20 g / m ² . This web was placed on a wire mesh belt having a width of 350 mm and a speed of 5 m / min, and hot air at a temperature of 140 ± 0.2 ° C. and a wind speed of 4 m / sec was blown for 5 seconds to thermally fuse the composite fibers to form a nonwoven fabric. The results of measuring the physical properties (specific volume, breaking length) of this nonwoven fabric are shown in Table 1.
It is shown in FIG. The relationship between the specific volume of the nonwoven fabric and the TD (transverse) breaking length is shown as a white circle 1 in FIG.

Examples 2 to 4 The heat of fusion ratio of polypropylene ΔH _{1 under} the same conditions as in Example 1 except that the heat treatment temperature and the crimping ratio were appropriately changed.
/ ΔH ₂ and the heat shrinkage of the single yarn at 130 ° C. were within the limited range of the present invention, and three types of composite fibers were obtained. Table 1 shows the physical properties of the single fiber of the obtained composite fiber.

Next, a nonwoven fabric was produced using the obtained composite fiber under the same conditions as in Example 1. Table 1 shows the physical properties (specific volume, breaking length) of the obtained nonwoven fabric, and FIG. 1 shows the relationship between the specific volume of the nonwoven fabric and the TD breaking length.
(Example 3) is shown as a white circle 4 (Example 4).

Comparative Examples 1-4 Unstretched denier was changed from 8.0de to 6.0de, and the stretching ratio was 5.
Except having changed from 0 to 3.7, it carried out similarly to Example 1, and obtained four types of comparative composite fibers. In these comparative conjugate fibers, the heat of fusion ratio ΔH ₁ / ΔH ₂ of the polypropylene was 0.42 to 0.52 as shown in Table 1 and was within the limited range (0.
35 or less).

Next, a nonwoven fabric was produced using these comparative conjugate fibers under the same conditions as in Example 1. The physical properties (specific volume, breaking length) of the obtained nonwoven fabric are shown in Table 1, and the relationship between the specific volume of the nonwoven fabric and the TD breaking length is shown in FIG.
These are shown as black circle 2 (Comparative Example 2), black circle 3 (Comparative Example 3), and black circle (Comparative Example 4).

Next, the relationship between the specific volume and the breaking length of the nonwoven fabrics obtained in Examples 1 to 4 and Comparative Examples 1 to 4 will be discussed.

As is clear from FIG. 1, in the nonwoven fabrics obtained in Examples 1 to 4, white circles 1 to 4 indicating the relationship between the specific volume and the TD breaking length are present on the straight line A at a high level. Table 1
As is clear from the above, the nonwoven fabrics of Examples 1 to 4 have a high MD fracture length of 6360 to 8800 m.

On the other hand, as is clear from FIG.
In the nonwoven fabrics obtained in Nos. 1 to 4, black circles 1 to 4 indicating the relationship between the specific volume and the TD breaking length exist at a low level near the straight line B. As is clear from Table 1, Comparative Examples 1 to 4
The nonwoven fabric has a MD breaking length of 5020 to 7430 m, and has a lower value than the nonwoven fabrics of Examples 1 to 4 when compared with the same specific volume (bulk height).

From these results, the nonwoven fabrics of Examples 1 to 4 were compared with Comparative Example 1
It was found that the TD breaking length and the MD breaking length were much higher than those of the nonwoven fabrics of No. 4 to 4, and thus the fusion strength was much higher.

Examples 5 and 6 Polypropylene was produced under the same conditions as in Example 1 except that the stretching ratio was changed from 5.0 to 4.7 (Example 5) and 4.5 (Example 6), and the crimp rate and the like were appropriately changed. Thus, two types of composite fibers were obtained in which the heat of fusion ratio ΔH ₁ / ΔH ₂ and the heat shrinkage of the single yarn at 130 ° C. were within the limits of the present invention. Table 1 shows the physical properties of the single fiber of the obtained composite fiber.

Next, a nonwoven fabric was prepared using these composite fibers under the same conditions as in Example 1. Table 1 shows the physical properties (specific volume, breaking length) of the obtained nonwoven fabric, and FIG. 1 shows the relationship between the specific volume of the nonwoven fabric and the TD breaking length.
This is shown as (Embodiment 6).

As is clear from FIG. 1, the nonwoven fabrics of Examples 5 and 6 indicated by white circles 5 and 6 have a slightly smaller TD breaking length than the nonwoven fabric of Example 3 indicated by white circles 3 and having substantially the same specific volume. It is only low, and as is clear from Table 1, the MD breaking length is also a satisfactory value, and it has been revealed that the material has a considerable fusion strength.

Comparative Example 5 A comparative conjugate fiber was obtained in the same manner as in Example 5, except that the heat treatment temperature was changed from 110 ° C to 105 ° C. The single fiber properties of the obtained comparative nonwoven fabric are shown in Table 1. In this comparative conjugate fiber, the single yarn has a heat shrinkage at 130 ° C. of 3.2%, which is a limited range of the present invention (3.0% or less). ) Was not included.

Next, using this comparative conjugate fiber, a nonwoven fabric was prepared under the same conditions as in Example 1. The physical properties (specific volume, breaking length) of the obtained nonwoven fabric are shown in Table 1, and the relationship between the specific volume of the nonwoven fabric and the TD breaking length is shown as a black circle 5 in FIG.

As is clear from FIG. 1, a black circle 5 showing the relationship between the specific volume of the nonwoven fabric of Comparative Example 5 and the TD breaking length is a black circle 5 showing the relationship between the specific volume of the nonwoven fabrics of Comparative Examples 1 to 4 and the TD breaking length. Although it is higher than the straight line B corresponding to almost 1 to 4, it is considerably lower than the straight line A corresponding to the white circles 1 to 4 showing the relationship between the specific volume of the nonwoven fabrics of Examples 1 to 4 and the TD breaking length. It became clear that the wearing strength was inferior.

From these results, in order to obtain a nonwoven fabric having high fusion strength while maintaining a desired specific volume (bulkiness), the heat of fusion ratio of polypropylene as a high melting point component ΔH ₁ / Δ
H ₂ is 0.35 or less, and the thermal shrinkage at 130 ° C. of single yarn is less than 3.0%, it has been found that it is necessary to use a heat-fusible composite fiber of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, there is provided a sheath-core type heat-fusible conjugate fiber suitable for obtaining a nonwoven fabric having high fusion strength while maintaining desired bulkiness. Was.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the specific volume and the TD breaking length of the nonwoven fabrics obtained in Examples 1 to 6 and Comparative Examples 1 to 5, and FIG. 2 is a composite fiber of the present invention. 3 is a graph showing a DSC curve of polypropylene in Example 1.

Claims (2)

(57) [Claims] 1. A sheath-core type heat-fusible conjugate fiber obtained by melt-spinning one of a high melting point component and a low melting point component as a sheath component and the other as a core component. 130 but made of polypropylene, the heat of fusion of low-melting portions of the polypropylene [Delta] H _1, the heat of fusion ratio ΔH ₁ / ΔH ₂ when the heat of fusion of high-melting portions and [Delta] H ₂ is 0.35 or less, and the single yarn A sheath-core heat-fusible conjugate fiber having a heat shrinkage at 3.0 ° C. of 3.0% or less. 2. A non-woven fabric obtained from the sheath-core type heat-fusible conjugate fiber according to claim 1.