JPH02133614A - Heat-fusible conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber giving non-woven fabric having desired bulkiness, high fusion tenacity and specific value of heat shrinkage of single fiber by using polypropylene having specific physical properties as high-melting point component of sheath or core component. CONSTITUTION:A high melting component of polypropylene having <=0.35 ratio of heat of fusion H1/ H2 putting heat of fusion of low-melting point component as H1 and heat of fusion of high-melting point component as H2 is used to either of sheath or core component and low melting component as remainder, then subjected to conjugate melt spinning to afford the aimed sheath- core type fiber having <=3% heat shrinkage of single fiber at 130 deg.C. Besides, crystalline polymer is preferable as polypropylene and polyethylene is preferable as low-melting point component.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to heat-fusible composite fibers, and more specifically, to heat-fusible composite fibers suitable for obtaining a nonwoven fabric having desired bulkiness and high fusion strength. Concerning composite fibers.

[Prior Art] As is well known, nonwoven fabrics are manufactured by hot-air fusing sheath-core heat-fusible conjugate fibers arranged in three-sheath-core configurations of a plurality of fiber components having different melting points. The properties required of the nonwoven fabric obtained by hot-air fusing these heat-fusible conjugate fibers include high fusing strength, bulk, and good texture. In particular, with regard to fusion strength, when used in disposable diapers, for example, there is a desire to further improve performance in order to prevent diapers from tearing when putting on and taking them off. The emergence of heat-fusible conjugate fibers has been desired.

[Problems to be Solved by the Invention] Therefore, 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 problems, and includes a high melting point component and a low melting point component, one of which is used as a sheath component and the other as a core component. In the heat-fusible composite fiber formed by melt composite spinning, the high-melting point component is made of polypropylene, and the melting temperature of the polypropylene when the heat of fusion of the low-temperature melting portion is ΔH1 and the heat of fusion of the high-temperature melting portion of the polypropylene is ΔH2. The heat ratio △H1, /△H2 is 0.35 or less, and the heat shrinkage rate of the single yarn at 130°C is 3°0.
% or less.

The present invention will be explained in detail below.

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

In the heat-fusible composite fiber of the present invention, polyethylene such as high-density polyethylene is preferably used as the low-melting point component, but materials other than 5 polyethylene may also be used as long as they have a lower melting point than the high-melting point component described below. be able to.

On the other hand, the high melting point component is limited to polypropylene. It is preferable to use crystalline polypropylene as this polypropylene, but other polypropylenes such as -
A copolymer to which ethylene or the like is added may also be used.The low-melting point component and the high-melting point component may contain various stabilizers commonly used for polyolefin fibers, to the extent that they do not impair the purpose of the present invention. , fillers, pigments, etc. can be added.

In the present invention, this polypropylene has a heat of fusion of ΔH1 in its low-temperature melting part and Δ■ in its high-temperature melting part.
Heat of fusion ratio Δt■1/'ΔH2 when 12 is 02
9 This heat of fusion ratio, H1/ΔH2, which is an essential condition of 35 or less, is determined by performing differential scanning calorimetry (hereinafter referred to as DSC) on the composite fiber. The details are as follows. That is,
According to the method of JIS K7122, sample 5 of a composite fiber containing polypropylene as a high melting point component is heated at a heating rate of 10°C/min in a nitrogen atmosphere, and a DSC curve is drawn. In the composite fiber of the present invention, the D of polypropylene is
As shown in Figure 2, the SC curve has two peaks, namely, the peak P1 of the low-temperature melting portion and the peak P1 of the high-temperature melting portion.
It has 2.

Next, find the areas of the shaded area S1 of the low-temperature melting part P and the shaded area S2 of the high-temperature melting part P2, and from each area, calculate the heat of fusion ΔH of the low-temperature melting part of the polypropylene.
1. Determine the heat of fusion ΔH2 of the high-temperature melting portion.

Finally, the two heats of fusion obtained above △H1゜△H2
The heat of fusion ratio ΔH1/ΔH2 is determined from

As mentioned above, in the composite fiber of the present invention, it is an essential condition that this heat of fusion ratio I-(1/ΔH2) is 0.35 or less.The reason is that if this value is less than 0.35, If so, a nonwoven fabric having high fusion strength while maintaining the desired bulkiness cannot be obtained.Composite fibers whose DSC curve of polypropylene shows only one peak are excluded.

Furthermore, in the composite fiber of the present invention, it is an essential condition that the heat shrinkage rate 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 fusion strength while maintaining the desired bulkiness cannot be obtained.

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

Example 1 Two single-screw extruders, 4 cylinders with hole diameter of 0, and 500 holes
Using composite fiber spinning equipment with a nozzle of
0, MI = 20> is the sheath component, and the high melting point component is crystalline polypropylene (Ube Industries (Kiku) Sl 15M, MI-
15> as a core component, the yarn was spun at a spinning temperature of 240° C. and a take-up speed of 700 m/min to obtain a single yarn denier of 8. A sheath-core type composite fiber of Ode was obtained. Note that the sheath component and the core component are arranged concentrically, and their cross-sectional area ratio is 1:1.

This multifilament was stretched at a stretching ratio of 5.0 using stable fiber prototype equipment, oiled, crimped,
After drying, heat treatment was performed with hot air at 110°C for 15 minutes, and then cutting was carried out. Single yarn denier 2 de, cut length 51 mnv
, a composite fiber with a crimp count of 18/+nch and a crimp rate of 13% was obtained. Regarding this composite fiber, the heat of fusion ΔH of the low-temperature melting portion of crystalline polypropylene and the heat of fusion Δl-12 of the high-temperature melting portion are determined according to JIS K 7122, which has already been explained.
As shown in Table 1, they were calculated based on the method of
35 or less), and 13 of the mana single yarn.
The heat shrinkage rate at 0°C also falls within the limited range of the present invention (3.0%
It was 2.3% included in the following).

The material was passed through a No. 42 stable fiber pull card machine three times to create a uniform web with a basis weight of 20 g/I. This web is 350 m high and the speed is 5 m.
The composite fibers were placed on a wire mesh belt at a temperature of 140±0.2° C. and a wind speed of 4 m/SeC for 5 seconds to thermally fuse the composite fibers to produce a nonwoven fabric. Physical properties of this nonwoven fabric (
The results of measuring the specific volume and tearing length are shown in Table 1, and the relationship between the specific volume and TD (transverse direction) tearing length of the nonwoven fabric is shown as white circle 1 in FIG.

Example 2-4 The heat of fusion ratio ΔH of polypropylene was determined under the same conditions as Example 1 except that the heat treatment temperature and crimp ratio were changed as appropriate.
/ΔH2 and single yarn heat shrinkage rate at 130'C are included in the limited range of the present invention, three types of composite fibers were obtained. Table 1 shows the physical properties of the single filament of the obtained composite fiber.

Next, a nonwoven fabric was produced using the obtained composite fibers under the same conditions as in Example 1. The physical properties (specific volume, tear length) of the obtained nonwoven fabric are shown in Table 1, and the relationship between the specific volume and T'D tear length of the nonwoven fabric is shown in Figure 1, with white circles 2 (Example 2) and white circles 3, respectively. (Example 3) and white circle 1 (Example 4).

Comparative Examples 1 to 4 Unstretched denier 8. 6 from Ode. Four types of comparative conjugate fibers were obtained in the same manner as in Example 1, except that the stretching ratio was changed from 5.0 to 3.7. In these comparative composite fibers, the heat of fusion ratio of polypropylene to 8
As shown in Table 1, 1/H2 was 0.42 to 0.52 and was not included in the limited range of the present invention (0.35 or less).

Next, using these comparative conjugate fibers, a nonwoven fabric was created under the same conditions as in Example 1.9 The physical properties (specific volume, tearing length) of the obtained nonwoven fabric are shown in Table 1. , the specific volume of the nonwoven fabric and T
The relationship between D fracture length is shown in Figure 1, each black circle 1 (comparative example)
．． ), black circle 2 (comparative example 2), black circle 3 (comparative example 3), and black circle (comparative example 4).

Next, the relationship between specific volume and tearing length for 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 specific volume and TD tearing length are at a high level and exist approximately on straight line A. Also Table-1
As is clear from the figure, the MD tearing length of the nonwoven fabrics of Examples 1 to 4 is 6360 to 8800 m, which is a high value.

On the other hand, as is clear from FIG.
In the nonwoven fabric obtained in 4, black circles indicating the relationship between specific volume and TI) tearing length] ~4 exist at a low level in the vicinity of straight line B. Furthermore, as is clear from Table 1, Comparative Example 1
The nonwoven fabrics of Examples 1 to 4 have MD tearing lengths of 5020 to 7430 m, and when compared with the same specific volume (bulk height), the nonwoven fabrics of Examples 1 to 4
value is lower than that of non-woven fabrics.

From these results, it can be seen that the nonwoven fabrics of Examples 1 to 4 are the same as those of Comparative Examples 1 to 4.
It became clear that the TD tearing length and MD tearing length were much higher than that of the nonwoven fabric No. 4, and therefore the fusion strength was much higher.

Examples 5 and 6 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 ratio was changed as appropriate. Under the same conditions as above, two types of composite fibers were obtained whose heat of fusion ratio ΔH1/H2 of polypropylene and heat shrinkage rate of single yarn at 130° C. were within the limited range of the present invention. Table 1 shows the physical properties of the single filament of the obtained composite fiber.

Next, a nonwoven fabric was created using these composite fibers under the same conditions as in Example 1. The physical properties (specific volume, tearing length) of the obtained nonwoven fabric are shown in Table 1, and the relationship between the specific volume and TD tearing length of the nonwoven fabric is shown in Figure 1, with white circles 5 (Example 5) and 6, respectively.
(Example 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 tear length than the nonwoven fabric of Example 3, which has the same specific volume and is indicated by white circles 3. Furthermore, as is clear from Table 1, the MD tearing length was also a satisfactory value, so it was clear that it had 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.9 The physical properties of the single fibers of the obtained comparative nonwoven fabric are shown in Table 1. In this comparative composite fiber, the heat shrinkage rate at 130"C of a single yarn is 3.2"'! 6 and the limited range of the present invention (3,0
(% or less).

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

As is clear from FIG. 1, black circle 5 indicates the relationship between the specific volume and TD tear length of the nonwoven fabric of Comparative Example 5, and black circle 1 indicates the relationship between the specific volume and TD tear length of the nonwoven fabric of Comparative Examples 1 to 4. Although it is above straight line B, which approximately corresponds to 4, it is considerably lower than straight line A, which corresponds to white circles 1 to 4, which indicate the relationship between the specific volume and TD tearing length of the nonwoven fabrics of Examples 1 to 4. It became clear that it was less powerful.

From these results, in order to obtain a nonwoven fabric with high fusion strength while maintaining the desired specific volume (bulkness), it is necessary to adjust the heat of fusion ratio △H1/△ of polypropylene as a high melting point component.
It has been found that it is necessary to use the heat-fusible conjugate fiber of the present invention, which has H2 of 0.35 or less and a single yarn having a heat shrinkage rate of 360% or less at 130°C.

(The following is a blank space) [Effects of the Invention] As detailed above, the present invention provides a sheath-core type heat-fusible composite suitable for obtaining a nonwoven fabric having high fusion strength while maintaining desired bulk. fiber provided.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the specific volume and TD breaking length of the nonwoven fabrics obtained in Examples 1 to 6 and Compound Examples 1 to 5, and Fig. 2 is a graph showing the DSC curve of polypropylene in the composite fiber of the present invention. This is a graph showing.

Claims (2)

[Claims] (1) A sheath-core heat-fusible composite fiber formed by melt-spinning a high melting point component and a low melting point component, one of which is used as a sheath component and the other as a core component, wherein the high melting point component is made from polypropylene. The heat of fusion ratio △H_1/△H_2 is 0.35 or less when the heat of fusion of the low-temperature melting portion of this polypropylene is △H_1 and the heat of fusion of the high-temperature melting portion is △H_2, and the temperature of the single yarn is 130°C. A sheath-core type heat-fusible composite fiber having a heat shrinkage rate of 3.0% or less. (2) A nonwoven fabric obtained from the sheath-core type heat-fusible conjugate fiber according to claim (1).