JP2853859B2 - Undrawn polyamide crimped yarn - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an undrawn polyamide crimped yarn exhibiting excellent crimpability and luster.

More specifically, the present invention relates to an undrawn polyamide crimped yarn having excellent actual crimping and gloss by a method based on a high-speed spinning method, not by crimping obtained by mechanical processing such as false twisting.

[Conventional technology]

By mechanical processing methods such as false twist processing and indentation processing,
Crimped yarns of polyamides such as nylon 6 and nylon 66 are produced in large quantities and widely used in socks and carpets.

However, the production of crimped yarn by such mechanical processing requires an expensive processing machine and requires a large amount of energy and labor. Therefore, the obtained crimped yarn becomes extremely expensive.

JP-A-56-15413 discloses that the yarn after spinning is air-cooled, an aqueous liquid is applied at a stage when a specific yarn temperature is reached, and then stretched, whereby when subjected to heat treatment, crimping is performed. It has been proposed that a naturally crimpable polyamide fiber exhibiting the following can be obtained.

The method disclosed in this publication is an excellent method for producing a naturally crimped yarn. However, the stretched yarn disclosed in this publication develops crimp for the first time by heat treatment, and cannot be used in a process where it is used without heat treatment because it has no crimp. Further, according to the publication, it is clarified that a 10 to 30 denier thick denier required for a carpet or the like is taken at a high speed of 3000 m / min or more at a high speed, and there is a problem that luster is lost and the commercial value is reduced. Was.

On the other hand, Japanese Patent Application Laid-Open No.
It is disclosed that when performing high-speed spinning for more than one minute, by spinning through an aspirator between a spinneret and a winder, a single yarn constituting the obtained fiber has a distribution of birefringence in the radial direction. ing. However, nylon 66 fiber obtained by this method has a distribution of birefringence in the radial direction, that is,
The interference fringes observed with a transmission interference microscope are symmetric with respect to the central axis of the single yarn, and crimps do not occur in principle. On the other hand, if the single yarn denier exceeds about 8 denier, the problem of devitrification of the fiber becomes remarkable, resulting in poor practicality.

[Problems to be solved by the invention]

The present invention has the same performance as a mechanically processed polyamide crimp yarn before being subjected to heat treatment, can be used for applications such as socks and carpets, has excellent luster, and An object of the present invention is to provide an undrawn polyamide crimped yarn that can be manufactured at a lower cost than a typical processed yarn.

[Means for solving the problem]

The present inventors have conducted intensive studies on high-speed spinning of polyamide, and as a result, applied an aqueous liquid to the yarn immediately after spinning and quenched,
A naturally crimped yarn capable of generating a natural crimp by high-speed drawing and subsequent heat treatment was found, and was previously filed as Japanese Patent Application No. 63-140506.

Thereafter, as a result of further study, if the temperature of the yarn immediately after spinning at the time of applying the aqueous liquid is extremely high, a high crimp can be realized while being pulled at a high speed, and the obtained winding The present inventors have found that the crimped yarn is transparent and exhibit excellent gloss, and have reached the present invention.

An object of the present invention is to have an average birefringence of 40 × 10 ⁻³ or less, a large birefringence distribution in the radial direction of the fiber, and this distribution is asymmetric with respect to the central axis of the single yarn, eccentric, and The birefringence of the lowest part is less than 20 × 10 ^-3 , and the elongation at break
This is achieved by an apparently crimped unstretched polyamide crimped yarn, which is 50% or less and has an apparent crimp elongation of 10% or more.

In the present invention, it is necessary that the average birefringence is 40 × 10 ⁻³ or less in order for the undrawn polyamide crimped yarn to have excellent gloss and high apparent crimp before heat treatment.

The average birefringence is measured by a method described later using a transmission interference microscope. In this measurement, if the cross section of the single yarn is circular, interference fringes are observed.

The fiber of the present invention has a large birefringence distribution in the radial direction,
Moreover, this distribution is asymmetric with respect to the central axis of the single yarn and is eccentric. The birefringence of the lowest part in the distribution is about 20
× 10 ^-3 or less. It is inferred that the presence of such a low birefringence portion reduces the average birefringence, resulting in excellent gloss and high current crimp.

Although interference fringes cannot be observed when the cross-sectional shape of the single yarn is non-circular, the decrease in the average birefringence itself can be regarded as an increase in the distribution within the single yarn.

When the average birefringence is 30 × 10 ⁻³ or less, more excellent gloss and obvious crimp can be obtained when used for socks and carpets.

When the average birefringence exceeds 40 × 10 ⁻³ , the distribution of birefringence in a single yarn is small, and the onset of crimp is poor. Furthermore, the transparency of the fibers becomes insufficient.

The undrawn polyamide crimped yarn of the present invention has an apparent crimp elongation rate.
It is necessary to have 10% or more. By having such a high apparent crimp elongation, it can be used as a crimped yarn without heat treatment. If the apparent crimp elongation is less than 10%, the bulkiness of the product is insufficient. Preferred crimps have an apparent crimp elongation of 20% or more.

The crimped yarn of the present invention has an actual crimp in which the crimp has already developed in a state after spinning, but the crimp can be increased by performing a heat treatment as needed.

When the crimp elongation rate after the heat treatment is defined as the total crimp elongation rate, the ratio of actualization before the heat treatment is preferably about 50% or more.

The elongation at break of the undrawn polyamide crimped yarn of the present invention needs to be 50% or less. If the elongation at break exceeds 50%, the fibers are stretched due to the stress of elongation received in a later step such as knitting, so that the crimp disappears and the undrawn fibers cannot be put to practical use as they are. The crimped yarn of the present invention,
Even though it is an undrawn fiber, the breaking elongation is extremely small, so that it can be put to practical use without being drawn. If the elongation at break is 40% or less, the same handling as ordinary drawn yarn can be performed in knitting and the like, and excellent crimp can be maintained.

FIG. 1 shows a typical elongation-stress curve of a crimped polyamide yarn. The curve a. In FIG. 1 is an undrawn polyamide crimped yarn of the present invention having an elongation at break of 50% or less, and the curve D.
Indicates a fiber having a breaking elongation of more than 50%.

Generally, fibers obtained by high-speed spinning of polyamide are
As the spinning speed increases, the low birefringence-high elongation changes from high birefringence-low elongation.
As described in Japanese Patent Application Publication No. 09, the undrawn polyamide crimped yarn of the present invention has a great feature in that it has a low birefringence and a low elongation.

The polyamide in the present invention may be a known polyamide such as nylon 66, nylon 6, nylon 46, nylon 12, or the like, and may be a polyamide obtained by a known polymerization method. Nylon 66 or nylon 6 is preferable in terms of price.

Further, the polyamide may contain additives such as a heat stabilizer and an antistatic agent.

The cross-sectional shape of the fiber is not particularly limited, but the trilobal or triangular cross-section further exerts the excellent gloss of the present invention.

The single yarn denier of the crimped yarn of the present invention is not particularly limited, but when used for ordinary socks or the like, about 1 d to 10 d
However, when used for carpets, etc., about 8d to 30d
Is adopted. In the present invention, even if the denier of single yarn is about 10 d or more, high transparency can be obtained without any generation of spherulites in the fiber.

Next, a method for producing an undrawn polyamide crimped yarn of the present invention will be described with reference to the accompanying drawings showing an example of an apparatus used for producing an undrawn polyamide crimped yarn of the present invention.

 FIG. 2 shows an apparatus used for producing the fiber of the present invention.

Using a known melt spinning machine, the melted polyamide is extruded from the spinneret 2 of the spin head 1 into a cooling atmosphere to form the fiber 3 and is drawn to the winding section 5 without drawing at a high speed of about 4500 m / min or more. Take up. Each single yarn spun at that time is
Before being cooled to 200 ° C. or lower, the aqueous liquid is applied from one side of each single yarn so that the single yarns do not come into contact with each other, and rapidly cooled. As the aqueous liquid, water or an oil solution used for ordinary spinning is used. Water is conveniently used.

In this method, the application of the aqueous liquid is preferably performed using an oiling nozzle guide 4 or an oiling roll. The application position of the aqueous liquid varies depending on the denier of the single yarn to be spun and the spinning speed, but is preferably applied approximately 10 cm to 60 cm below the spinning surface. In this position, each single yarn is 200 ℃
By applying an aqueous liquid from one side of each single yarn and quenching it before cooling, a structure having a low birefringence and a low elongation characteristic of the battlefield of the present invention is exhibited.

In the present invention, the take-off speed needs to be about 4000 m / min or more. When the take-off speed is lower than this, the apparent crimp elongation before the heat treatment is less than 10%, and the object of the present invention is not achieved. A preferred range for the take-off speed is from about 5000 m / min to about 9000 m / min, more preferably from about 5500 m / min to about
It is 8000m / min.

When the take-off speed exceeds about 7000 m / min, it is desirable to provide a heating zone 6 below the spinning surface for the purpose of achieving spinning stability.

In the present invention, by taking out at such a high speed, a polyamide crimped yarn that can be supplied to a knitted fabric without being subjected to a subsequent stretching step can be obtained.

〔Example〕

 The present invention will be described in detail with reference to examples.

The method for measuring the properties of the polyamide crimped yarn of the present invention is described below.

Single yarn temperature The single yarn temperature was measured in a non-contact manner along the spinning line using a scanning infrared thermometer.

・ Average birefringence and distribution
Use green light (wavelength 549mμ) parallel to the fiber axis
Refractive index n for oscillating light And perpendicular to the fiber axis
Refractive index n for moving light_⊥From the average birefringence
The rate Δn is Δn = n -N_⊥It is represented by

When the cross section of the single yarn is circular, V-shaped or U-shaped interference fringes are observed, and from this interference fringe, the radial birefringence distribution of the cross section of the single yarn is calculated. As the average birefringence, a volume average value represented by the following equation was used.

-Elongation at break A tensile test was performed at an initial length of 20 cm and a tensile speed of 20 cm / min using a TENSILON LTM-II-20 type tensile tester manufactured by Toyo Baldwin, and the elongation at break was measured.

・ Crimp elongation rate Applicable crimp elongation rate: 77 rounds of polyamide undrawn crimped yarn 1.12
Using a 5m measuring machine, make a skein with 20 turns. After humidity control in a room with constant temperature and humidity (temperature 20 ± 2 ° C, relative humidity 65 ± 2%),
A load of 2 mg / d in skein, to measure the hank length l ₁ after 30 seconds. Then skein to measure the hank length l ₂ to 30 seconds after applying a load of 0.1 g / d. The apparent crimp elongation is represented by the following equation.

Total crimp elongation; heat-treat the skein in boiling water under no load at 98 ° C for 5 minutes, and then adjust the humidity in a room at constant temperature and humidity all day and night. Measuring the hank length l ₃ after 30 seconds humidity controlled fiber under a load of 2 mg / d. Then skein to measure after 30 seconds subjected to the skein length l ₄ a load of 0.1 g / d. The total crimp elongation is expressed by the following equation.

The measurement should be performed for each sample in consideration of the sample variation.
Ten points were measured and the average value was shown.

Gloss The knitted fabric was prepared with a knitting machine, and the gloss of the knitted fabric was evaluated by the naked eye under white light.

 Excellent glossy ○ Somewhat excellent △ Devitrified ×.

Example 1 η _γ = 2.60 Nylon 66 dissolved in 95% sulfuric acid was measured and a hole having a Y-shaped cross section was formed using a melt spinning machine shown in FIG.
The mixture was melt-spun at 305 ° C. through a spinneret having individual pieces. At this time, the spinning speed was 7000 m / min, the denier of single yarn was 16 denier, and water was applied to each single yarn from one side by a water supply nozzle. The height of the water supply nozzle at that time, that is, the single yarn temperature at the position where water was applied was variously changed.

Table 1 shows the average birefringence, apparent crimp elongation, total crimp elongation after heat treatment, elongation at break, and gloss of the obtained fibers.

As shown in Table 1, when water is not applied, or when water is applied at a single yarn temperature of less than 200 ° C., a sufficient apparent crimp cannot be obtained.

Example 2 The spinning speed was changed to 3000, 4000, 5000, 6000, 7000, 8000 m / min, the temperature at the point where water was applied was 230 ° C., and the unstretched crimped yarn of nylon 66 was the same as in Example 1 I got

 Table 2 shows the properties of the obtained crimped yarn.

As shown in Table 2, when the spinning speed is less than 4000 m / min, even if water is applied at a single yarn temperature of 230 ° C., the actual crimping and the total crimp elongation are insufficient. Further, the elongation at break was also large.

[Effect of the Invention] The performance of the undrawn polyamide crimped yarn of the present invention is not inferior to conventional processed yarns, and has excellent luster. Therefore, it can be widely used for all uses of crimped yarn.

In addition, the undrawn pyramide crimped yarn of the present invention is lower in cost than conventional processed yarn and can be supplied at low cost as crimped yarn for socks and carpets.

Cut the undrawn polyamide crimped yarn of the present invention into a staple fiber, and use it for spun yarn or futon cotton,
Excellent gloss is exhibited.

[Brief description of the drawings]

FIG. 1 is an elongation-stress curve of a polyamide crimped yarn. Curve a is an undrawn polyamide crimped yarn according to the present invention, and curve b is a polyamide crimped yarn outside the present invention. FIG. 2 is a schematic front view of an apparatus used for producing the fiber of the present invention. 1 ... spin head, 2 ... spinneret, 3 ... fiber, 4 ... water supply nozzle guide, 5 ... winding section, 6 ... heating area

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D01F 6/60

Claims (1)

(57) [Claims] (1) an average birefringence of 40 × 10 ^-3 or less, a large birefringence distribution in the radial direction of the fiber, and this distribution is asymmetric with respect to the central axis of the single yarn, eccentric, and most eccentric. Birefringence of a low portion is 20 × 10 ⁻³ or less, elongation at break is 50% or less, and apparent crimp elongation is 10% or more. yarn.