JPS62299514A - Thermally bondable hollow conjugated yarn - Google Patents

Abstract

PURPOSE:Thermally bondable yarn which is conjugated yarn having eccentrically existing high-melting core part and low-melting sheath part and a hollow part at the core part wherein the center of the hollow part is approximately coincident with the center of the sheath part and provides nonwoven fabric having bulkiness, improved elasticity recovering properties, good flexibility and feeling. CONSTITUTION:In sheath-skin type conjugated yarn, thermally bondable yarn wherein a core part 1 consists of a high-melting polymer and has a hollow part 2 continuing in the longer direction and a sheath part 3 comprises a low- melting polymer having a melting point 20 deg.C lower than the component of the core part 1, the core part 1 eccentrically exists in the sheath part 3 and the center of the hollow part 2 approximately coincides with the center of the sheath part 3. The center ratio is preferably 5-40%. The eccentric ratio of the core part 1 and the hollow part 2 is preferably 0.10-0.70.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a heat-adhesive hollow composite fiber that has excellent bulkiness and elastic recovery properties and is particularly suitable as a material for nonwoven fabrics. .

(Conventional technology) Heat-adhesive conjugate fibers made of two components with different melting points can be bonded between fibers without using adhesives, so they do not require drying and require energy It is economical with low consumption, and is widely used as a fiber material for various non-woven fabrics, including sanitary materials that avoid the inclusion of substances harmful to the human body such as formalin. -4767 Publication, Special Publication No. 1977
As seen in Japanese Patent Publication No. 12830 or Japanese Patent Publication No. 55-483, polyolefin composite fibers in which polypropylene and polyethylene are arranged in a parallel type or core-sheath type do not contain harmful substances and can be used at relatively low temperatures. Can be thermally bonded
Because of its soft texture and excellent chemical resistance, this type of thermally adhesive fiber is most commonly used for various nonwovens.

(Problems to be Solved by the Invention) However, conventional heat-adhesive composite fibers are not necessarily satisfactory in terms of bulk and elastic recovery. For example, when producing a nonwoven fabric with a soft μ texture using heat-adhesive conjugate fibers in whole or in part, a carded web of the conjugate fibers,
Alternatively, a random web is subjected to hot air processing or embossing roll processing to melt only the low melting point components of the composite fibers, and bonding between the fibers is performed to create a nonwoven fabric with improved strength. The bulkiness is surprisingly poor compared to the web before adhesive processing. The nonwoven fabric after being thermally bonded is usually rolled up into a paper tube and shipped or stored. is small, so the bulkiness is significantly impaired compared to before winding.

The present invention provides a heat-adhesive conjugate fiber that is rich in bulk and elastic recovery without impairing the flexibility, good feel, high strength, and other features of nonwoven fabrics made of heat-adhesive conjugate fibers. be.

(Means for Solving the Problems) The thermoadhesive fiber according to the present invention 1 has a fiber-forming thermoplastic polymer as a core component and has a melting point at least 20° C. lower than that of the core component. A polymer is used as a sheath component, and a core component (a hollow part is formed in the length direction of the fiber, and the hollow part is located concentrically with respect to the sheath component and eccentrically with respect to the core component). The bending moment of the fiber is increased due to the presence of the hollow part.
However, due to the presence of eccentricity of the hollow part with respect to the core component, a moderate rλ
The crimp is ensured, and a nonwoven fabric with excellent bulk and elastic recovery properties can be obtained.

As the core component polymer of the heat-adhesive composite fiber of the present invention,
Polypropylene/polyethylene terephthalate and the like are preferred, and examples of the polymer for the sheath component include high density polyethylene, medium density polyethylene, low density polyethylene, ethylene/vinyl acetate copolymer, and polypropylene.

In addition, before thermal bonding processing of fiber aggregates or nonwoven fabrics using heat-adhesive composite fibers made of these two different components, the sheath component is added to the core component in order to avoid undesirable effects such as heat shrinkage and softening of the core component. It is necessary that the melting point of the polymer is at least 20° C. lower than the melting point of the polymer constituting the polymer.

As shown in the attached drawings, the composite fiber of the present invention has a hollow portion (2) formed in the core component (1) in the cross section of the fiber; is at an eccentric position, and the center point (0 and the hollow part (2) of the core component (1)
The center point (with the distance from (12) as lal, the core component (1)
When the radius of is tri, the eccentricity ratio (DI is expressed as D-1, but when the eccentricity ratio 1 (11) is less than 0.10, the occurrence of crimp is small and the fiber assembly after thermal bonding is The bulkiness and elastic recovery of the body will be poor, and if the eccentricity ratio tDl exceeds 0.70, there is a risk that a part of the hollow part (2) will be exposed outside the core component (1), and the hollow part (2)
If a part of the core component (1) is located outside the core component (1), the sheath component (3) melted during the thermal bonding process will flow into the hollow part, resulting in loss of bulk and elastic recovery (thus, the above-mentioned It is desirable that the eccentricity ratio (D+) be in the range of 0.10 to 0.70.In order to impart a uniform crimp form to the composite fiber before heat treatment and to improve the card passability, the above-mentioned Preferably, the hollow part (2) is in a concentric position with respect to the sheath component (3).

Further, the area ratio (hollowness ratio) of the hollow portion (2) to the core component (1) is preferably about 5 to 40%.

Here, the hollowness ratio is determined by the following formula.

If the hollowness ratio is less than 5%, bulkiness and elastic recovery properties will be poor, and if it exceeds 40%, the hollow portion will be easily crushed under high load, resulting in loss of bulkiness and elastic recovery properties.

The fibers of the present invention may be used alone as a fiber material for nonwoven fabrics, etc. (or may be used in combination with other types of fibers, but in order to obtain a hot liquid effect, it is preferable to mix 30% by weight or more. .

(Function) Since the sheath component in the core-sheath type composite fiber of the present invention is substantially concentric with the hollow portion existing within the core component, the structural impact of the core component due to the eccentricity between the core component and the hollow portion It suppresses the development of anisotropy and prevents excessive crimp development due to relaxation heat treatment after drawing the composite fiber, resulting in a composite fiber with moderate crimp and good card passability. Since there is a hollow part in the core component, even if the sheath component melts during thermal bonding, the hollow part remains in the core component, and the presence of this hollow part increases the bending moment of the fiber. ,
Improves bulk and elastic recovery.

It should also be noted that the composite fiber of the present invention has a carded web state [where fj<
Another object of the present invention is that the nonwoven fabric after being thermally bonded can have excellent bulkiness and elastic recovery properties. case), the bulkiness of the nonwoven fabric after thermal bonding is better than the bulkiness of the carded web state. This is because after the sheath component of the composite fiber is melted by thermal bonding, the hollow part is eccentric with respect to the core component, so the core component released from the constraints of the sheath component exhibits structural anisotropy due to the eccentricity of the hollow part. This is due to the appearance of three-dimensional crimps depending on the nature of the body.

Once bulky, the nonwoven fabric is stabilized as a fiber aggregate by adhesive bonding between the fibers.
Combined with the elastic recovery properties of the fiber itself, it exhibits high elasticity and good recovery properties.

(Example) Polypropylene with a melting point of 167°C and a melt fluorate of 5 at 230°C was used as the core component (1), and a melting point power of 132
℃, high-density polyethylene with a melt index of 26 and a density of 0.960 is used as a sheath component (3), and both are supplied in a separate extrusion manner to perform melt extrusion, and a composite material having a hollow nozzle hole with an outer diameter of about 1.2 is obtained. When spinning from a spinneret (40 nozzles), a hollow part (2) exists in the core component and the core component (
A core-sheath type hollow composite fiber was spun with a composite ratio (cross-sectional area ratio) of 1) and sheath component (3) of 1:1.Then, this core-sheath type hollow composite fiber was heated and stretched to form a staff. 1 with a box crimper or without mechanical crimping.
After relaxing heat treatment at 10° C. for 15 minutes, the fibers were cut into 51-inch lengths and used as staple fibers.

The web obtained by supplying this staple fiber to a roller card is processed by a hot air penetrating thermal processing machine under no load.
The sheath component was melted by heating at .degree. C. for 1 minute to obtain a nonwoven fabric in which the fibers were adhesively bonded. Examples 1-8 and Comparative Example 1 above
-2 results are as shown in Table 1.

Next, polyethylene terephthalate with a melting point of 255°C and an intrinsic viscosity of 0.72 and high-density polyethylene with a melting point of 132°C, a melt index of 28, and a density of 06955 were
They were fed into separate extruders for melt extrusion, and both were introduced into a composite spinneret (number of nozzle holes: 120) having hollow nozzle holes with an outer diameter of 1.3 mm, so that polyethylene terephthalate became the core component and had a high density. A core-sheath type hollow composite fiber was spun, in which BoIJ Echire/ was used as a sheath component, a hollow part existed in the core component, and the composite ratio of the core component and the sheath component was 1=1. After the yarn is drawn to a predetermined reliability, mechanical crimp is applied with or without mechanical crimp using a stuffer box type crimper (
After relaxing heat treatment at 115℃ for 15 minutes, it became 51mm.
The fibers were cut into lengths to obtain stable fibers.

This staple fiber was made into a carded web, which was heated unloaded in a hot air penetrating processing machine for 1 minute at 140° C. to thermally bond it to form a nonwoven fabric in which the fibers were bonded.

The results of Examples 9 and 10 and Comparative Examples 3 and 4 are shown in Table 2.

Table 2 Note that the eccentricity ratio of Comparative Example 1 in Table 1 and Comparative Example 3 in Table '52 was calculated from the eccentricity ratio of the core component and the sheath component. In addition, the thickness of the nonwoven fabric is the value obtained by measuring under a load of 0.1 to 2 d and converted to a basis weight of 40 Vrd, and the texture of the nonwoven fabric is determined by a sensory evaluation test conducted by five panelists. The average rating was ``soft'', and ``soft'' was ◎.
○ for ``ya\soft'', Δ for ``ya\hard゛'', and X for ``hard''
The thickness after removing the tsumata weight is 15 cm vertically.
Layer 10 pieces of nonwoven fabric cut at 150 mm horizontally, and make the fabric weight 4.
It was compressed to a thickness of 0.1 mm per sheet, which corresponds to the thickness of the nonwoven fabric in a rolled state in terms of 0H, and after - weeks, the weight was removed, and after leaving it in that state for 24 hours, it was compressed to a thickness of 0.1 mm.
The value is the value obtained by converting the thickness measured under a load of 40 mm to a basis weight of 40 mm, and the bulk retention rate is expressed as .

(Effects of the Invention) As described above, the heat-adhesive hollow conjugate fiber according to the present invention has a core component that is higher than a high melting point polymer having a continuous hollow portion in the length direction, and a melting point that is at least 20° C. lower than that of the core component. and a sheath component made of a low melting point polymer having
Regardless of whether or not mechanical crimping is applied, three-dimensional crimping occurs during the relaxing heat treatment, resulting in good card passage properties, and the nonwoven fabric after thermal bonding has a bulk that is equal to or greater than that of the carded web. maintain sexuality. In addition, the presence of hollow parts increases elastic recovery, and when the nonwoven fabric wound into a roll is rolled out, the bulkiness is significantly recovered, the texture is soft, and the nonwoven fabric is highly elastic. Toru.

Therefore, the nonwoven fabric obtained by using the heat-adhesive hollow conjugate fiber according to the present invention or by mixing the hollow conjugate fiber with the heat-adhesive hollow conjugate fiber is as follows:
It is suitable as a sanitary material that requires a soft texture and bulkiness, and its good elastic resilience prevents the backflow of liquid in the absorbent core material, making it particularly suitable as a surface material for the absorbent core material. be.

Furthermore, since the nonwoven fabric using the hollow composite fibers of the present invention has high elastic recovery properties, even if it is stored for a long period of time while being rolled up in a paper tube during the manufacturing process of the nonwoven fabric, its bulkiness is restored when it is unfolded, and it can be compressed and rolled. This helps eliminate the inconvenience that bulkiness is reduced due to removal.

Furthermore, since it has thermal adhesive performance equivalent to that of conventional thermal adhesive fibers, it is suitable for use not only in nonwoven fabrics for sanitary materials, but also in textile products in various fields that require bulkiness and elastic recovery.

[Brief explanation of drawings]

The drawing is an enlarged cross-sectional view of the composite fiber of the present invention, in which (1) is a core component, (2) is a hollow part, and (3) is a sheath component.

Claims (13)

[Claims] (1) A core component made of a high melting point polymer having a hollow part continuous in the length direction, and at least 20°C higher than the core component.
and a sheath component made of a low melting point polymer having a low melting point, and the center point of the hollow portion is eccentric from the center point of the core component and almost coincides with the center point of the sheath component. hollow composite fiber (2) The hollow ratio of the above hollow part to the core component is 5 to 40%
The heat-adhesive hollow composite fiber according to claim 1. (3) The area ratio of the core component and sheath component in the fiber cross section is 1
The heat-adhesive hollow composite fiber according to claim 1, wherein the ratio is 1 to 2:1. (4) Eccentricity ratio between core component and hollow part is 0.10 to 0.70
The heat-adhesive hollow composite fiber according to claim 1. (5) The heat-adhesive hollow conjugate fiber according to claim 1, wherein the core component is polypropylene and the sheath component is high-density polyethylene. (6) The thermoadhesive hollow conjugate fiber according to claim 1, wherein the core component is polypropylene and the sheath component is medium density polyethylene. (7) The heat-adhesive hollow composite fiber according to claim 1, wherein the core component is polypropylene and the sheath component is low-density polyethylene. (8) The heat-adhesive hollow conjugate fiber according to claim 1, wherein the core component is polypropylene and the sheath component is an ethylene/vinyl acetate copolymer. (9) The heat-adhesive hollow composite fiber according to claim 1, wherein the core component is polyethylene terephthalate and the sheath component is high-density polyethylene. (10) Claim 1 above wherein the core component is polyethylene terephthalate and the sheath component is medium density polyethylene.
The heat-adhesive hollow composite fiber described in . (11) Claim 1 above wherein the core component is polyethylene terephthalate and the sheath component is low density polyethylene.
The heat-adhesive hollow composite fiber described in . (12) The heat-adhesive hollow conjugate fiber according to claim 1, wherein the core component is polyethylene terephthalate and the sheath component is an ethylene/vinyl acetate copolymer. (13) The thermoadhesive hollow composite fiber according to claim 1, wherein the core component is polyethylene terephthalate and the sheath component is polypropylene.