JPS6358933B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a composite fiber of polyurethane elastomer and polyamide, and relates to a method for producing a composite fiber that can utilize both the elasticity of fine crimps and the elasticity of the elastomer itself. In particular, the purpose is to obtain crimped elastic fibers with excellent elastic recovery, good dimensional stability, and high fit properties by drawing and heat-treating undrawn yarn obtained by melt-spinning both of the above components in a specific state. .

In general, 100% polyurethane elastic thread has only rubber elasticity, and its elongation reaches 400-500%, making it difficult to use as it is, so the elongation should be increased to 200-500%.
As a method for suppressing this by up to 300%, a so-called covering yarn is used, which is a urethane elastic yarn wrapped with a crimped yarn or a flat yarn in a single or double layer. However, the urethane yarn used in such covering yarns is obtained by a wet spinning method or a dry spinning method, and the productivity is inferior to that using a melt spinning method. Furthermore, since a covering step is added, the cost increases. Moreover, covering yarn cannot have the bulkiness of crimped yarn, and is only used in special fields that require only stretch, such as the rubber parts of socks and some sports clothing. is the current situation.

On the other hand, in order to overcome the drawbacks of such covering yarns, polymers with different heat shrinkability were added to the sides.
Composite fibers that have latent crimp ability and are laminated into a by-side type or an eccentric sheath core type, using polyurethane elastomer as one component and polyamide as the other component (Special Publication No. 55-36725, Japanese Patent Publication No. 36725, 55−
No. 27175) is proposed.

Such composite fibers are fine, have many crimps, and have excellent crimp performance, so they are used in fields where crimp elasticity is required, such as pantyhose. However, although composite fibers using these polyurethane elastomers utilize the heat shrinkability of the polyurethane elastomer and are effective in producing fine crimps, the elasticity (rubber elasticity) properties of the polyurethane elastomer itself are hardly utilized. do not have. In other words, although these composite fibers use urethane elastomer, which itself exhibits elasticity, they only utilize crimped fibers in the form of composite fibers. Stretching did not receive any attention at all.

As a result of intensive studies to eliminate such conventional drawbacks, the present inventors bonded polyurethane elastomer and polyamide together in a specific composite state, and then carried out stretching and crimping heat treatment to improve bulk and elasticity due to crimping. The present inventors have discovered that it is possible to obtain crimped elastic fibers at low cost that have rubber elastic properties unique to elastomers in addition to the rubber elastic properties unique to elastomers.

That is, in the production of a side-by-side crimped composite fiber in which one of the components is a polyurethane elastomer (component U) and the other component is a polyamide (component A), the present invention involves composite melting of both components. After heat-treating the undrawn yarn obtained by spinning, it is subjected to a relaxation heat treatment using a heated fluid nozzle, and at that time, the spinning and heat treatment are carried out so that the following conditions are satisfied, and the boiling water shrinkage rate of the resulting crimped yarn is This is a method for producing crimped elastic fibers, which is characterized by adjusting the content of crimped elastic fibers to 2.2% or less.

Conditions ~ The shape of the cross section of the composite fiber is flat, has a constriction in the middle part in the flat direction, and satisfies the following formula [I] [], and each cross section has a long axis passing through the center of gravity of the cross section. The center of gravity of the component exists [I] Formula a/b = 1.2 to 4 [However, a: Length of the major axis passing through the center of gravity b: Length of the minor axis perpendicular to the major axis] [Formula] of the U component Area/area of component A = 0.65 to 1.5 Processing temperature after stretching: room temperature to 120°C Heating fluid temperature: 80 to 150°C Relaxation rate during relaxation heat treatment: 10% or more The present invention will be explained in more detail. The present inventors have studied various types of yarn structures for elastic yarns that have the highest stretchability and can utilize both the elasticity due to crimping and the rubber elasticity due to the elastomer regarding composite crimped fibers of polyurethane elastomer and polyamide. As a result, the cross-sectional shape of the fiber is cocoon-shaped, that is,
It has been found that the most preferable structure is a composite crimped fiber in which both components are bonded together so that the center of gravity of both components is located on the major axis of the constricted part in the middle part in the flat direction. That is, the composite crimped fiber having such a cross-sectional shape is in a coiled crimped state at the initial stage of elongation, as shown in FIG. As shown in (b), the stretched urethane is used as a core component and nylon is spirally wound around it, creating a so-called screw structure. Furthermore, when the yarn in this state is stretched, the spiral nylon will eventually become completely stretched as shown in Figure 4C. In this process,
The crimp elasticity dominates until the screw structure is formed, and the rubber elasticity of the elastomer dominates from the screw structure until the spiral disappears.

Elastic yarn suitable for clothing applications that has both of these elasticities can be manufactured with high productivity only when it satisfies all of the above-mentioned conditions and the boiling water shrinkage rate of the resulting crimped yarn is adjusted to 22% or less. .

In the present invention, the polyurethane elastomer, which is one of the components, must be able to be melt-spun, and usually has a melting point of 200 to 240°C and a hardness (JIS K-
6301) with a value of 90 to 100 can be used.
In addition, the other component, polyamide, includes nylon 6, nylon 66, nylon 610, nylon
11, nylon 12, nylon 13, etc. can be used. The combination of these two components is compatible so that the two components do not separate during the spinning, drawing, processing, and fabric making processes.
It is necessary to select a material with good bonding adhesive properties. From this point of view, it is particularly preferable to use caprolactone-based or polycarbonate-based polyurethane as the polyurethane elastomer. In order to improve the light resistance of these elastomers and polyamides, a light resistance improver such as a benzophenone compound, a benzotriazole compound, or an inorganic manganese compound may be added.

The conditions of ~ mentioned above will be explained in detail. The most important thing in the present invention is that the cross-sectional shape of the obtained composite fiber is flat as shown in FIG.
It has a constriction in the middle part in the flat direction, satisfies the following formula [I][], and has the center of gravity of each component on the major axis of the cross section.

[I] Formula a/b = 1.2~4 [] Formula Area of U component/Area of A component = 0.65~1.5 [However, a: Length of the major axis passing through the center of gravity b: Length of the minor axis perpendicular to the major axis Length U component: polyurethane elastomer component A component: polyamide component] A crimped fiber with such a cross-sectional shape can fully take the screw structure described above, and has the highest elasticity due to crimping and rubber elasticity due to the elastomer. It can be used often.

Moreover, such crimped fibers have good color fastness, strength,
Both elongation is good, and the texture of the final woven or knitted fabric is also good.

On the other hand, if the cross-sectional shape shown in Fig. 2 A and B is used, where a/b is less than 1.2, even if sufficient crimp development occurs as shown in Fig. 4 D, the screw The structure becomes weak and the rubber elasticity of the elastomer cannot be fully utilized, making it impossible to obtain the elastic yarn targeted by the present invention.

On the other hand, if a/b is greater than 4, the cross-sectional shape of the fibers becomes too flat, resulting in the final woven or knitted fabric having a rough feel and poor texture.
When crimping occurs, the diameter of the crimped coil increases, making it impossible to obtain fine crimping, and the elastic properties of the crimped fibers deteriorate.

Also, area of U component/area of A component (U/A)
When the value of is less than 0.65, the rubber elasticity of the crimped fiber obtained is almost gone because the U component is too small, and conversely, when the value of U/A is greater than 1.5,
Because the U component is too large, physical properties such as color fastness, strength, and elongation elasticity of the resulting crimped fibers deteriorate, making it unusable when made into a woven or knitted fabric.

A spinneret for obtaining a composite fiber having such a fiber cross-sectional shape by melt spinning uses a polyurethane elastomer component (referred to as U component) and an amide component (referred to as A component). A spinneret that discharges the spinneret independently and joins at one point immediately behind the spinneret surface, for example, the spinneret shown in Fig. 3, is suitable. Fig. 3 is a partial longitudinal sectional side view showing an example of the spinneret. U component and A component and each introduction hole 1,
3 and is discharged through the discharge holes 2 and 4. At this time, the above-mentioned a/b can be adjusted by the distance l between the discharge holes 2 and 4 and the angle Θ formed by both discharge holes. In the composite fiber targeted by the present invention, l
can be sufficiently obtained by adjusting Θ in the range of 0.3 to 0.1 mm and Θ in the range of 8 to 30 degrees.

Incidentally, the ratio (U/A) between the area of the U component and the area of the A component in the cross section of the fiber can be easily adjusted by changing the discharge amounts of both components. In order to make the thus obtained composite spun yarn into a crimped elastic fiber that can utilize both the crimped elasticity due to fine crimping and the rubber elasticity of the elastomer itself, which is the object of the present invention, it is necessary to It is important that the following conditions be satisfied when the spun yarn is heat treated after drawing and subjected to relaxation heat treatment using a heated fluid nozzle.

First of all, it is necessary that the boiling water shrinkage rate of the crimped yarn obtained after the relaxation heat treatment is 22% or less.
If the shrinkage rate of this crimped yarn is higher than 22%, weaving
The boiling water shrinkage rate, which has poor knitting properties and is also unfavorable in terms of product dimensional stability, tends to increase as the heat treatment temperature after stretching is lower or the heated fluid temperature is lower. As long as the heat treatment temperature and heating fluid temperature are within the range of conditions, it is fully possible to reduce the boiling water shrinkage to 22% or less.

It is necessary to set the heat treatment temperature after such stretching to between room temperature and 120°C. If the heat treatment temperature is higher than 120° C., the boiling water shrinkage rate of the resulting crimped yarn will be 22% or less, which improves dimensional stability, but reduces the crimp rate and makes it impossible to obtain desirable crimp elasticity.
Note that the stretching temperature is a normal temperature ranging from room temperature to 60°C.

Also, the fluid temperature of the heated fluid nozzle is 80~150℃
is necessary. If the fluid temperature is less than 80°C, the boiling water shrinkage rate will be high, which is unfavorable in terms of dimensional stability. On the other hand, when the temperature exceeds 150℃, the heat shrinkage rate decreases, but the elongation increases and it becomes easier to stretch.
In addition, the crimp rate decreases, making it impossible to obtain desirable crimp elasticity. As the fluid used here, air or steam is preferable, and air is particularly preferable since it is less noisy.

Incidentally, such heated fluid nozzles include nozzles conventionally used for relaxation heat treatment, such as Japanese Patent Publication No. 37576/1983, Japanese Publication Utility Model No. 9535/1983, and Japanese Patent Publication No. 1983/1986-9535.
The nozzle described in No. 37339 can be used.

Next, it is preferable that the relaxation rate during relaxation heat treatment with a heated fluid nozzle is 10% or more, particularly 10% or more and 40% or less. This is because the crimp rate varies greatly depending on the relaxation rate during relaxation heat treatment, so it is important to adjust the relaxation rate within the above range in order to obtain a crimped yarn with the desired crimp rate (crimping elasticity). It is. If the relaxation rate at this time is less than 10%, the crimp rate will also be low, making it impossible to obtain a crimped yarn having the crimp elasticity targeted by the present invention. In addition, this relaxation rate is determined by the following formula.

Relaxation rate (%) = Yarn speed before heated fluid nozzle - Yarn speed after heated fluid nozzle / Yarn speed before heated fluid nozzle x 100 The drawing and heat treatment process for producing such a crimped yarn involves so-called separate drawing, which is separated from spinning. Even in the method,
Alternatively, a so-called direct stretching method, which is directly connected to spinning, may be used. Furthermore, the so-called DTY method, in which the stretching and relaxation heat treatment steps are directly connected, or the so-called SDTY method, in which the spinning, stretching, and relaxation heat treatment steps are all directly connected, may be used, and any of these methods can be adopted.

As explained above, according to the present invention, a side-by-side type or eccentric sheath core type composite spun yarn in which a polyurethane elastomer and a polyamide are bonded in a specific state is subjected to the above-mentioned drawing and relaxation heat treatment conditions. By processing the fibers, it is possible to obtain crimped elastic fibers that can utilize both the crimped elasticity due to fine crimping and the rubber elasticity of the elastomer itself. As a result, an excellent crimped conjugate fiber with unprecedented high elastic recovery and elastic strength at high elongation can be obtained, making it extremely useful for pantyhose stuffing, stretch woven and knitted fabrics, and the like.

The present invention will be explained below with reference to Examples. The crimp rate (TC), boiling water shrinkage rate (Fs), stretch rate, stretch recovery rate, crimp elasticity modulus, and rubber elasticity modulus used here were measured by the following methods.

1) Crimp rate (TC), boiling water shrinkage rate (Fs) Take the yarn after relaxation heat treatment into a skein, and initial load 2
Apply a load of mg/de and measure the length of the skein after 1 minute by lo
shall be. Next, with the initial load applied, place it in boiling water.
Crimp treatment is carried out for 20 minutes, and then air-dried under the load for a day and a night. Next, total 200mg/de
Apply a load, read the length after 1 minute l ₁ , then remove the load, apply the initial load again and read the length after 1 minute l ₂ , crimp ratio (TC), boiling water shrinkage ratio ( FS) is calculated using the following formula.

Crimp rate (TC) (%) = l ₁ - l ₂ / lo x 100 Boiling water shrinkage rate (FS) = (%) = lo - l ₁ / lo x 100 2) Stretch rate, stretch recovery rate Measurement is based on relaxation The yarn after heat treatment was taken in a skein, an initial load of 2 mg/de was applied, crimp treatment was performed in boiling water for 20 minutes, and then the sample was air-dried overnight with the initial load applied at 20 ± 2°C at 65°C.
The test was carried out at a temperature and humidity of ±2% RH, and the thread was suspended in the following manner.

A Test yarn length: 200mm (yarn length under initial tension) B Initial tension: 2 mg/de C Test load: 5, 10, 20, 50, 100, 200,
500, 1000, 1500mg/de (suspend each load on the end of the thread so as not to rotate) D. Loading time: 3 minutes E. Measure the strain length after loading, and apply the initial tension after unloading.

F. Apply initial tension and measure the residual strain after 3 minutes.

G. The expansion/contraction rate and expansion/contraction recovery rate are calculated using the following formula.

Stretching rate (%) = Yarn length under load - Original yarn length / Original yarn length x 100 Stretching recovery rate (%) = Stretching recovery length (strain) / 1000 mg/de Stretching length under load (total strain) x 100 3) Winding Compression modulus, rubber elastic modulus The crimp-treated yarn obtained in the same manner as in 2) was applied to a Tensilon type tensile tester, and evaluated while observing the center of the sample with a 20x casetometer.
The conditions at this time were: sample surface 20cm, initial load 2mg/
de, elongation speed 100%/min, chart speed 20
cm/min, and the cassettemeter is
Start by focusing on cm. The degree of elongation of this crimped yarn until it reaches the screw structure described above is the crimp elastic modulus. Furthermore, the helix disappears by stretching, and the degree of elongation from the screw structure state until the helix disappears is the elastic modulus of the rubber. The average value of 5 measurements was taken.

Examples Nylon 6 with an intrinsic viscosity [η] of 1.1 (measured with m-cresol liquid at 30°C) and polyurethane elastomer components were commercially available thermoplastic polyurethanes such as Elastran E595 (Capro type) and Elastran E995 ( Carbonate type) (both manufactured by Nippon Elastolan KK) was used. nylon 6
is 247℃, polyurethane is 228℃ with E595, and
E995 was melted separately at 230°C, heated to 245°C, and composite spun using a side-by-side die as shown in Figure 3. The area ratio U/A of polyurethane and polyamide in the cross-section of the composite fiber is set to 1 by adjusting the discharge ratio of each component, and the cross-sectional shape is the shape shown in FIG. 1, and a/b is the shape shown in FIG. 3. l of
and Θ were adjusted to 1.5. Also,
The resulting spun yarn contains 0.6% by weight of silicone oil.
It was attached to form an undrawn yarn of 700 denier/12 filaments.

Next, the obtained undrawn yarn was wound once and tested using the DTY method, which directly connected the drawing and relaxation heat treatment steps in a separate process, or the SDTY method, which directly connected all the drawing and heat treatment steps without winding the obtained undrawn yarn. I did this. At this time, the elongation after stretching is 25 to 35%.
After being stretched and subsequently treated at various temperatures, it is directly connected and passed through a heated and compressed air nozzle.
The compressed air temperature and relaxation rate were varied at 1.0 Kg/cm ² G.
Table 1 also shows spinning, drawing, processing conditions, and physical properties of the obtained crimped yarn.

Table 1 also shows the results of spinning as shown in Figure 2A using a conventional side-by-side spinneret.

As shown in Table-1, No. 1~ that meet the conditions of the present invention
4. Crimp modulus is 85~ for No.7~9 and No.12~13
125%, the rubber elastic modulus is 35-80%, and the total elastic modulus is high at 120-200%, and the elasticity recovery rate under a load of 1.0g/de is over 80%, showing good stretchability and recovery. , it was possible to provide elastic fibers with no particular problems in terms of dimensional stability. On the other hand, No. 5 and No. 10, in which the post-stretching heat treatment temperature or heating and compressed air temperature is higher than the range of the present invention, and No. 11, whose relaxation rate is lower than the relaxation rate of the present invention, have good boiling water shrinkage rates, but The crimp elastic modulus and rubber elastic modulus were also low, and the stretch recovery rate was also poor at less than 80%.

In addition, when the heating and compressed air temperature is low as in No. 6, even if both the crimped elastic modulus and the rubber elastic modulus are good, the boiling water shrinkage of the obtained crimped yarn is as high as 25%, resulting in poor dimensional stability and poor practical use. Not suitable for

Furthermore, side-by-side type items such as No. 14, which have the cross-sectional shape shown in Figure 2 A, cannot take on a sufficient screw structure when extended.
The elastic modulus of the rubber was low and it did not have powerful stretching performance.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of the composite fiber of the present invention, Figure 2 is a cross-sectional view showing an example of a conventional composite fiber, and Figure 3 is a spinning yarn used when spinning the composite fiber of the present invention. FIG. 4 is a side sectional view showing one example of the cap, and FIG. 4 is a side view of the crimpable elastic fiber of the present invention. U represents a polyurethane elastomer, and A represents a polyamide component. Further, i indicates the center of gravity of the fiber cross section, a indicates the length of the major axis passing through the center of gravity i, and b indicates the length of the minor axis passing through the center of gravity i.

【table】

[Table] * Comparative example

Claims (1)

[Claims] One of the components is a polyurethane elastomer (U
component), and the other component is polyamide (component A), in the production of side-by-side crimped composite fibers, after drawing and heat-treating the undrawn yarn obtained by composite melt spinning of both components. , a relaxing heat treatment is carried out using a heated fluid nozzle, and at that time, the spinning and heat treatment are carried out so that the following conditions are satisfied, and the boiling water shrinkage rate of the obtained crimped yarn is adjusted to 22% or less. A method for producing crimped elastic fibers. Conditions ~ The shape of the cross section of the composite fiber is flat, has a constriction in the middle part in the flat direction, and satisfies the following formula [I] [], and each cross section has a long axis passing through the center of gravity of the cross section. The center of gravity of the component exists [I] Formula a/b = 1.2 to 4 [However, a: Length of the major axis passing through the center of gravity b: Length of the minor axis perpendicular to the major axis] [Formula] of the U component Area/area of component A = 0.65 to 1.5 Heat treatment temperature after stretching: room temperature to 120°C Heating fluid temperature: 80 to 150°C Relaxation rate during relaxation heat treatment: 10% or more