JPH0735607B2 - Elastic composite fiber and method for producing the same - Google Patents

Description

The present invention relates to a polypropylene-based elastic composite fiber having an excellent elastic recovery rate and a small stress during elongation. The elastic composite fiber of the present invention is preferably processed into a woven fabric, a knitted fabric or a non-woven fabric and is preferably used for applications such as bandages, supporters and sportswear.

Since polypropylene fiber has the advantages of low cost, low specific gravity, high strength, and excellent chemical resistance, it is used for industrial materials such as ropes and ropes, household items such as futon, carpets, and sanitary items such as diaper surface materials. Is used for. In recent years, paying attention to the hydrophobicity of polypropylene fibers,
Attempts have been made to use it for clothing such as sportswear, and a polypropylene cloth having appropriate elasticity has been required in order to fit the body well and to fit it. As a stretchable fiber for garment, an elastic recovery rate at 100% elongation of 80% or more and an elongation stress of about 0.6 g / d or less are suitable.

The conventional polypropylene fiber is obtained by spinning at a spinning temperature of 220 to 300 ° C., a spinning speed of 500 to 800 m / min, stretching 3 to 6 times at 110 to 120 ° C., and heat treating at about 100 ° C. for 200 to 300 seconds. Generally, elongation is 20 to 60%, elastic recovery is 50% or less, and it is a fiber with poor stretchability.Means such as post-processing with elastic resin such as polyurethane by devising the structure of woven and knitting have been taken. However, since the cost is high and the performance is not sufficient, it has been demanded that the fiber itself has elasticity.

After spinning polypropylene at a high speed of 1000 m / min or more,
It is known that a fiber having an excellent elastic recovery rate can be obtained by annealing at about 105 to 160 ° C for 30 to 60 minutes. Such a fiber is called a hard elastic fiber, which is elastic and has an elastic recovery rate of nearly 100% at 100% elongation, but the elongation stress during elongation is 1 g / d.
As described above, the flexibility of the stretchable clothing material is insufficient. For example, if a needle punching method using hard elastic fibers or a nonwoven fabric is tried to be stretched by an adhesive, the entanglement points of the fibers or the breaking of the bonding points occur before the fibers are sufficiently stretched, and a sufficient expansion / contraction effect cannot be exhibited. Even when it is used for knitted fabric, it is necessary to make the density of the hard elastic filament extremely small in order to have flexibility and elasticity according to the movement of the body, which is not practical.

The inventors of the present invention have earnestly studied to produce a polypropylene fiber having an excellent elastic recovery rate and a small elongation stress, and as a result, the first component made of crystalline polypropylene and the second component made of a fiber-forming thermoplastic resin have a composite ratio. (First component / second component) 60/40 to 40/60 arranged in a sheath-core type or a parallel type and then subjected to composite spinning, and then stretching the unstretched yarn at a stretching temperature of 10 to 50 ° C. to a draw ratio of 2 times or less. When the heat treatment temperature (T) is 100 to 150 ° C and the heat treatment time (t) is 0.913 ^T-170 or more, the elastic recovery rate at 100% elongation is 80% or more and the elongation stress is 0.6g. The inventors have completed the present invention by knowing that elastic composite fibers having a ratio of / d or less can be obtained.

The crystalline polypropylene used as the first component in the present invention is not only a homopolymer of propylene but also a copolymer containing propylene as a main component and ethylene or other α-olefin, and having a crystallinity of 40% or more. Means
If the crystallinity is less than 40%, the elastic recovery rate of the fiber will be insufficient.

Examples of the thermoplastic resin used as the second component in the present invention include thermoplastic resins other than crystalline polypropylene such as polyolefins, polyesters and polyamides which are usually used for producing synthetic fibers, ethylene vinyl acetate copolymer, ethylene propylene rubber and the like. It can be appropriately selected from the thermoplastic resins.

The combination of the first component and the second component may be selected on the basis that component separation does not occur in the composite fiber obtained by spinning, but each component should be compounded within a range not exceeding 60 wt%. I won't. When the first component exceeds 60 wt%, the tensile stress of the composite fiber at 100% elongation becomes 0.6 g / d or more, and when the second component exceeds 60 wt%, the elastic recovery rate at 100% elongation is 80.
%, Which is not preferable.

Both the selected components are arranged in a parallel type or a sheath-core type and are subjected to composite spinning. The one in which the first component is arranged on the core component side has a relatively small elongation stress, and the one in which the first component is arranged on the sheath side has a relatively large elastic recovery rate.

The undrawn yarn thus obtained has a drawing temperature of 10 to 50.
After being stretched at a draw ratio of 2 times or less at 0 ° C., it is heat treated at a heat treatment temperature (T) of 100 to 150 ° C. and a heat treatment time (t) of 0.913 ^T-170 seconds or more. If the drawing temperature is less than 10 ° C, the drawability is poor, and if it exceeds 50 ° C, the elastic recovery rate of the obtained composite fiber is lowered, which is not preferable. If the stretching ratio exceeds 2 times, the elastic recovery rate decreases and the elongation stress increases, which is not preferable. If the heat treatment temperature is less than 100 ° C, the time required for effective heat treatment will exceed 30 minutes, which is not practical.
If the temperature exceeds ℃, the softening point of the crystalline polypropylene, which is the first component, will be exceeded and heat shrinkage will occur in the composite fiber, which is not preferable.
Heat treatment time (t) is 0.913 ^T-170 seconds (T is heat treatment temperature,
If it is less than (° C.), The elastic recovery rate of the obtained conjugate fiber becomes insufficient. Although any heating means such as hot air, steam, infrared rays or the like can be used for the heat treatment, a hot air suction dryer is preferable because rapid, homogeneous and simple heat treatment can be performed.

The elastic fiber of the present invention using a thermoplastic resin having a melting point of 20 ° C. or more lower than the melting point of the first component as the second component is useful as a material for a nonwoven fabric having excellent stretchability by the thermal bonding method. The elastic composite fiber using the component as the sheath component has a small number of crimps and a large number of bonding points by the thermal bonding method, and is therefore useful as a material for a stretchable nonwoven fabric having flexibility and high strength.

The elastic composite fiber of the present invention has an elastic recovery rate of 80% at 100% elongation.
% Or more, it is extremely stretchable compared to ordinary polypropylene fiber, and the elongation stress at 100% elongation is 0.6 g / d.
It is as follows, which is more flexible than polypropylene fibers having a hard elastic structure and is suitable as a material such as a woven fabric or a nonwoven fabric having soft stretchability.

The present invention will be specifically described below with reference to Examples and Comparative Examples.

Elastic recovery rate at 100% elongation: According to JIS L 1015, using a self-recording constant-speed elongation type tensile tester, the sample was attached with a gripping interval of 100 mm under an initial load of 1 g / 15 d and a tensile speed of 50 % / Mi
Immediately after elongating to 100% with n, unload at the same speed and stop for 2 minutes from when the gripping interval reaches 100 mm. After the lapse of the stop period, the weight is again removed at the same speed, the elongation (1%) at the time when the elongation stress reaches the initial load, and the elastic recovery rate (%) = 100-1 is calculated.

Elongation stress at 100% elongation: Read from the record of the above elongation test.

Examples 1-5, Comparative Examples 1-5 As the first component, crystalline polypropylene (PP-1) having a specific gravity of 0.905 melt flow rate 8 or crystalline polypropylene (PP-2) having a specific gravity of 0.910 melt flow rate 8, second
Low density polyethylene (PE-1) with a specific gravity of 0.918 melt flow rate 18, nylon-6 (Ny1-6) with a molecular weight (n) of 9700, and specific gravity 0.880 melt flow rate 30 ethylene-propylene copolymer with an ethylene content of 20 wt% Was spun into a sheath-core type, drawn with a godet roll, and heat-treated with a hot-air suction dryer to obtain a composite fiber. Spinning and drawing,
Table 1 shows each condition of the heat treatment and the physical properties of the fiber. As shown in the examples, the fibers satisfying the conditions of the present invention have excellent elastic recovery and low elongation stress, but as shown in the comparative examples, the fibers not satisfying the conditions of the present invention have these physical properties. Either or both were inferior.

Examples 6 and 7, Comparative Example 6 The above-mentioned PP-1 or PP-2 was used as the first component, and the above-mentioned PE-1 or the melt flow rate 32 as a second component, an ethylene vinyl acetate copolymer having a vinyl acetate content of 5 wt% ( EVA) was spun in parallel and drawn and heat treated in the same manner as above to obtain a composite fiber. Table 2 shows the spinning, drawing, and heat treatment conditions and the fiber physical properties. Fibers satisfying the conditions of the present invention even in the parallel type conjugate fiber had an excellent elastic recovery rate and a low elongation stress.

Claims (4)

[Claims] 1. A first component made of crystalline polypropylene and a second component made of a thermoplastic resin other than the binding polypropylene.
Composite ratio with components (first component / second component) 60-40 / 40-60
The composite unstretched yarn obtained by arranging in a sheath-core type or a parallel type at a stretching temperature of 10 to 50 ° C. is stretched to a draw ratio of 2 times or less, and then a heat treatment temperature (T) of 100 to 150 ° C. ) Is 0.913 ^T-170 (sec) or more, elastic recovery rate at 100% elongation and elongation stress are 80% or more and 0.6 g / d or less, respectively. 2. The elastic composite fiber according to claim 1, wherein the second component is a thermoplastic substance having a melting point lower than the melting point of the first component by 20 ° C. or more. 3. The elastic composite fiber according to claim 2, wherein the second component is arranged on the sheath component side. 4. A first component made of crystalline polypropylene and a second component made of a thermoplastic resin other than crystalline polypropylene.
Composite ratio with components (first component / second component) 60-40 / 40-60
The composite unstretched yarn obtained by arranging in a sheath-core type or a parallel type at a stretching temperature of 10 to 50 ° C. is stretched to a draw ratio of 2 times or less, and then a heat treatment temperature (T) of 100 to 150 ° C. ) Is 0.913 ^T-170 (sec) or more, and a method for producing an elastic composite fiber having an elastic recovery rate at 100% elongation and an elongation stress of 80% or more and 0.6 g / d or less, respectively.