JP2598688B2 - Latent crimping conjugate fiber and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a latently crimpable conjugate fiber for a nonwoven fabric having excellent elasticity. This fiber can be handled in the same way as the fiber for nonwoven fabric conventionally used in the fiber opening, web forming, or papermaking process up to the formation of the nonwoven fabric. An excellent three-dimensional crimp can be exhibited, and one of the components of the composite fiber can be used as a heat-adhesive fiber because it melts at a relatively low temperature.

(Prior art) Japanese Patent Laid-Open No.
There is a rubber elastic nonwoven fabric disclosed in Japanese Patent No. 146004 and Japanese Patent Application Laid-Open No. Sho 61-225364, in which the fiber itself expands and contracts in a rubber-like manner, so that the nonwoven fabric has elasticity. JP-A-62-21855
Japanese Patent Application Laid-Open Publication No. H11-64300 discloses that the constituent fibers have a fine spiral crimp shape, and the elasticity of the spiral crimp obtains the elasticity of the nonwoven fabric.

(Problems to be Solved by the Invention) Since rubber elastic fibers cannot be mechanically opened by a carding machine or the like, currently commercially available rubber elastic nonwoven fabrics are manufactured by a spun bond method. Spunbond non-woven fabrics are not thick and only paper-like.
Its use is limited because it cannot be mixed with other fibers.

Nonwoven fabrics using three-dimensional crimped fibers are described in JP-A-62-78214. However, since the polyester composite fibers used here are non-thermally adhesive, the resulting nonwoven fabric has the disadvantage that it has low strength. is there. The heat treatment temperature for exhibiting crimp elasticity is as high as 130 ° C. or higher, preferably 160 ° C.
There is also a problem that a generally used steam heating type thermal processing machine has insufficient capacity.

The present invention relates to constituent fibers for obtaining a highly elastic nonwoven fabric,
Fibers that can be applied to dry-type nonwoven fabric processing systems that are currently in widespread use as they are, that is, they have card permeability, heat treatment temperature of 130 ° C or less for the appearance of crimp, and latent crimpability with thermal adhesion at 150 ° C or less It is intended to provide a conjugate fiber.

(Means for Solving the Problems) The inventors of the present invention have studied to achieve such an object, and in particular, have studied the use of high-density polyethylene (hereinafter abbreviated as HDPE) and polybutylene terephthalate (hereinafter abbreviated as TBT). Latent crimpable conjugate fiber by combination was found.

That is, the latently crimpable conjugate fiber of the present invention has a density of 0.958 g.
/ cm ³ or more, consisting of a first component composed of HDPE and a second component mainly composed of PBT. It is a latently crimpable conjugate fiber in which the conjugate ratio of both components is 70:30 to 30:70, arranged in a core-sheath type in which the centers of gravity of the components do not overlap at one point.

The first component, HDPE, must have a density of 0.958 or more. If it is smaller than this, the crimped shape of the conjugate fiber cannot be sufficiently developed, and the non-woven fabric with high elasticity, which is the object of the present invention, is obtained. Has insufficient crimpability. The conjugate fiber of the present invention obtained by using HDPE having a density of 0.958 g or more exhibits a high degree of three-dimensional crimpability by heat treatment. When fully developed, the crimped shape is a double helical shape, and the nonwoven fabric obtained by using this exhibits a high elasticity performance that has never been seen before.

The higher the heat treatment temperature is, the better the crimping property is expressed.
If the melting point is higher than the melting point of the first component, HDPE, the fibers will adhere to each other and the high elasticity will decrease.
HDPE is desirable, but for convenience, the melting point of HDPE increases as its density increases.
Since it is 137 ° C at 0.964, the heat treatment temperature for crimp development that does not cause thermal bonding can be set to 125 to 130 ° C. When a crimp is developed and then heat-bonded with a spot bond heat roll, a high-strength elastic nonwoven fabric is obtained.

PBT as the second component may be either a copolymer or a homopolymer. Further, polyethylene terephthalate or polycarbonate may be mixed and used, but PBT must be at least 60% or more. If the PBT is less than 60%, it is difficult to obtain sufficient crimp expression.

Such a first component and a second component have a complex ratio (first component /
The second component is combined in the range of 30/70 to 70/30.
In addition, the composite structure of the two components can be obtained by arranging the composite component in a parallel type in which the first component is placed on the outside and the second component is placed on the inside in the core-sheath type. It is possible to obtain the desired composite fiber having a high crimp developing ability. In the case of the core-sheath type, it is necessary that the first component, HDPE, is on the outside not only for exhibiting the heat bonding performance but also for achieving sufficient crimping. Further, also in this case, if both components are completely concentric, sufficient crimp development cannot be expected.

The above composite structure will be described with reference to the drawings. FIG. 1 shows a parallel type in which a first component (1) and a second component (2) are stuck together in a dorsum shape, and FIG. 2 shows a first component (1). Outer, core-sheath type with the second component (2) inside. FIG. 3 shows an example of an inappropriate core-sheath structure in which the first component and the second component (2) are concentric, and the centers of gravity of both components coincide. First to first
FIG. 2 shows an example of a conjugate fiber having a circular cross-sectional shape, but the present invention is not limited to this, and may be another shape such as a polygon.

Next, a method for producing a latently crimpable conjugate fiber having such a structure will be described. The second invention of the present invention is the first invention
Drawing the composite spun yarn of HDPE and PBT having the composition and structure according to the invention of the present invention at a drawing temperature (T ° C.) of 30 <T <90 and a draw ratio (n times) of 1.5 <n <4 with hot water. This is a method for producing a three-dimensionally crimped conjugate fiber.

Generally, as the draw ratio of the latently crimpable conjugate fiber is increased in the drawing step, the crimping manifestation by the subsequent heat treatment is also increased. However, the conjugate fiber of the present invention may be unstretched by stretching the undrawn yarn three times or more. The appearance of crimp by heat treatment tends to gradually become poor, and when stretched more than 4 times, the three-dimensional crimp tends to hardly have a double helical structure. Also, the draw ratio (n
The same tendency is observed even when the ratio is 1.5 times or less. Therefore, the stretching ratio is preferably in the range of 1.5 <n <4, preferably 2.5 ≦ n ≦ 3.5.

On the other hand, if the stretching temperature exceeds 90 ° C, the crimp development by the subsequent heat treatment is inferior, and if the stretching temperature is less than 30 ° C, a part of the three-dimensional crimps will appear in the drying process (about 50 ° C), which hinders the nonwoven fabric manufacturing process. Come. Therefore, the stretching temperature (T ° C.) is 30 <T
<90, preferably 50 ≦ T ≦ 80.

In addition, it is preferable to pass through a stuffer box after stretching to give a regular mechanical crimp because three-dimensional crimp can be uniformly developed.

(Operation) The latently crimpable conjugate fiber of the present invention obtained as described above has a gentle curved crimp by drawing, or has a regular planar bent crimped shape by mechanical crimping. However, when heat treated at 125-130 ° C for 30-60 seconds, a three-dimensional crimp with a three-dimensional helical structure is developed, and the number of crimps is as small as 25 per 25 mm. This is shown in FIG. In particular, those with good expression have a large number of double helixes as shown in FIG. A non-woven fabric made of constituent fibers that exhibit such crimps can have high elasticity and elasticity.

Further, when heat-treated at about 140 ° C., the first component, HDPE, is melted, so that it can be used as a heat bonding fiber.

(Examples) Examples 1 to 9, Comparative Examples 1 to 3 HDPE having a density of 0.964 or more was used as a sheath component, and P was used as a core component.
Using a polymer mixture consisting of BT or PBT and other components, eccentric sheath-core composite fibers or side-by-side composite fibers are melted at a composite ratio of 1: 1 at a spinneret number of holes of 500 and a discharge rate of 280 g / min. Spun. After spinning, it is stretched in hot water, mechanically crimped in a stuffer box, dried through a 50 ° C net conveyor dryer, and cut to a cut length of 51 mm to obtain a latently crimpable conjugate fiber. Was.

Table 1 shows the composition of the components, spinning conditions, and drawing conditions of each example.

Next, each fiber was heat-treated at 125 ° C for 55 seconds to develop crimp. Table 1 shows the crimp shape and the number of crimps of each example. For the crimped shape, visually observe the fiber left unloaded, and
The number of crimps per 25 mm for each ten pieces was counted, and the average was taken as the number of crimps.

(Effect of the Invention) The latently crimpable conjugate fiber obtained by the present invention has the following excellent advantages as a fiber constituting an elastic nonwoven fabric.

Good card passing properties and easy web formation. Until heat-treated, it has a gently curved shape by stretching and mechanical crimping, or a shape with a regular planar bending crimp. Good shape.

Since the crimp onset temperature is 120 to 130 ° C., the crimp onset treatment can be sufficiently performed by a steam heating type thermal processing machine which is currently widely used in the nonwoven fabric industry.

Furthermore, since one of the composite components is HDPE, its melting point is 14
It is about 0 ° C, and after crimping, it can be heat-sealed.

[Brief description of the drawings]

1 and 2 are cross-sectional views of a fiber showing one embodiment of the conjugate fiber of the present invention. FIG. 3 is a cross-sectional view of a fiber showing the structure of a composite fiber capable of expressing only a loose three-dimensional crimp, which is out of the object of the present invention. FIG. 4 and FIG. 5 are views showing the state of the three-dimensional crimping of the composite fiber. In the following figures, (1) is the first component and (2) is the second component.

Claims (2)

(57) [Claims] 1. A first component comprising high-density polyethylene having a density of 0.958 g / cm ³ or more, and a second component comprising polybutylene terephthalate as a main component, wherein both components are of a parallel type or a first component in a fiber cross section. Potential crimpability with the core as the sheath, the second component as the core, and the center of gravity of the two components arranged in a core-sheath shape that does not overlap at one point, with a compound ratio (cross-sectional area ratio) of both components of 70:30 to 30:70 Composite fiber. 2. A fiber comprising a first component composed of high-density polyethylene having a density of 0.958 g / cm ³ or more and a second component composed mainly of polybutylene terephthalate, and a second component composed of a sheath or the first component sheathed in a fiber cross section. The components are placed in a core-sheath shape with the components as cores and the centers of gravity of both components do not overlap at one point. The composite ratio (cross-sectional area ratio) of both components is set to 70:30 to 30:70, and melt-spinning is performed. ) Is 30 <T <90, and the stretching ratio (n times) is 1.5 <n <4.
A latently crimpable conjugate fiber, which is drawn with hot water.