JPS6319603B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently producing copolyamide fibers having aromatic amide units with high stiffness and high strength. Aliphatic polyamides such as nylon 6 and nylon 66 and wholly aromatic polyamides such as poly-p-phenylene terephthalamide are industrially produced and extremely useful polyamides.
The former is generally said to be capable of melt polymerization and melt spinning.
Nylon 66 is an excellent polyamide that has established a solid position in terms of ease of handling and versatility. For example, nylon 66 is often used as tire cord fiber due to its high strength, but it has poor dimensional stability. However, there is a desire to improve the properties to make them more rigid. On the other hand, fully aromatic polyamides such as poly-p-phenylene terephthalamide have aromatic rings with a rigid structure, so they are polymers with excellent mechanical properties such as extremely good rigidity. It is unavoidable that a significant increase in cost is inevitable due to the complexity of production as it cannot be subjected to melt polymerization or melt spinning, and it cannot be denied that it is greatly inferior to the aforementioned aliphatic polyamide in terms of versatility. In order to solve these problems, aliphatic-aromatic copolyamides that can be melt-polymerized and melt-spun have also been proposed, but such copolyamides can be melt-spun and melt-spun under the conditions applied to conventional aliphatic polyamides.
Even with stretching, it is difficult to produce high-strength yarn with good operability. The present invention provides a method for efficiently producing high-strength yarn from a highly rigid copolyamide, in which a copolyamide containing 1 to 50 mol% of aromatic amide units is melt-spun, and after cooling and solidifying, the yarn is spun at 1000 m/min. Take it off at the above speed, then stretch at a stretching ratio of 92 to 98% of the cutting stretching ratio to 100 to 20°C below the melting point of the copolyamide.
The gist of this invention is a method for producing copolyamide fibers, which is characterized by hot drawing at a low temperature. Conventionally, when producing high-strength yarns from aliphatic polyamides such as nylon 66, high-molecular-weight polymers are used and melt-spun at low spinning speeds of about 200 to 600 m/min. Obtain a drawn yarn;
A method has been adopted in which this is highly oriented and crystallized by hot stretching, and high strength yarns cannot be obtained at high spinning speeds. However, when the present inventors investigated copolyamides having aromatic amide units, they found that such copolyamides have higher melt viscosity and activation energy than aliphatic polyamides, and exhibit different orientation and crystallization behavior during melt spinning. However, it was found that such copolyamides do not yield high tenacity yarns at low spinning speeds, but high tenacity yarns can be obtained at high spinning speeds. Figure 1 is a diagram showing an example of the relationship between spinning speed and strength of drawn yarn, where the solid line shows nylon 66 salt copolymerized with 25 mol% of paraphenylenediamine and terephthalic acid (mixture of 1/1 molar ratio). Copolyamide (6.25 mol% aromatic amide units), melt viscosity 2900 poise at 290℃, activation energy 22kcal/
The molar one, the dotted line is nylon 66, and the melt viscosity is
At 290℃, the activation energy is 2000 poise.
Shown is 14kcal/mol. The method of the present invention will be explained in detail below. In the present invention, the aromatic amide unit means a unit having an amide bond sandwiched between aromatic rings,
Copolyamides are those that can be melt-spun (melting point is 200
~350℃) and a high degree of polymerization are desirable. A typical example of the copolyamide used in the present invention is a copolyamide of diamine and dicarboxylic acid that can be synthesized by melt polymerization and that can be melt-spun and contains 1 to 50 mol% of the following aromatic amide units. copolyamides. [R ¹ and R ² are hydrogen or lower alkyl groups, X, Y
is a phenylene group, a naphthylene group, a biphenylene group in which the bonding chains both extend in the same or parallel axes, or -φ-Z-φ- {φ is a paraphenylene group,
Z is -O-, -S-, -SO ₂ -, -CO-, -NH
--, --CH ₂ --, --(CH ₂ ) ₂ --or --C(CH ₃ ) ₂
-}] During melt spinning, molten copolyamide kept at a temperature 20 to 40 degrees Celsius higher than its melting point is spun out from a spinneret, cooled and solidified using a horizontal or cylindrical spray device, and then oiled, etc. After the
It is picked up at a high speed higher than min. At this time, in order to better exhibit the effect of high spinning speed, it is desirable to increase the spinning draft.
It is preferably 75 or more, particularly 100 or more. Further, it is desirable to reduce the fineness of the single filaments, and it is preferable that the fineness of the single filaments after drawing is about 2 to 8 d. The undrawn yarn obtained by melt spinning has a residual elongation of 3~
Although the yarn is drawn to be about 30% drawn, the drawing may be done by drawing an undrawn yarn that has been wound once, or by a so-called spin-draw method in which drawing is performed directly after spinning. If the spinning speed is relatively low and the elongation of the undrawn yarn is 200% or more, two-stage drawing may be performed, but we adopt a high spinning speed so that the elongation of the undrawn yarn is 200% or less. It is industrially advantageous to carry out the stretching in substantially one stage. In any case, the stretching is 92, which is the cutting stretching ratio.
At a stretch ratio of ~98%, below the melting point of the copolyamide
It is necessary to carry out the stretching at a temperature 100 to 20°C lower (in the case of two-stage stretching, the temperature of the second stage), and unless these conditions are met, it will not be possible to obtain a yarn with sufficient performance and good operability. Following stretching, heat treatment can be performed at an elongation rate of 0.95 to 1.10 to obtain a yarn with better dimensional stability. Further, in the spinning and drawing steps, it is also preferable to perform an interlacing treatment to facilitate handling of the yarn. Further, the copolyamide used for spinning can contain various additives such as a heat-resistant agent, a light-resistant agent, a coloring agent, and an antistatic agent. According to the present invention, copolyamide fibers suitable for industrial materials having a strength of 8 g/d or more and an initial Young's modulus of 70 g/d or more can be produced with good operability. The present invention will be explained in more detail below using Examples. The relative viscosity ηr shown in the examples is
This is a value measured at 25°C for a solution dissolved in 100ml of 98% sulfuric acid. The melt viscosity μ (poise) is the viscosity value at zero load measured with a flow tester at a load of 4 to 25 Kg/cm ² with a 0.5 mm nozzle, and the activation energy E (Kcal/mol) is: This is a value determined from the temperature dependence of μ according to a conventional method. In Tables 1 and 2, the numbers marked with a circle are examples of the present invention, and the others are comparative examples. Example 1 Melting point was determined by melt polymerization from nylon 66 salt (75 mol%) and an equimolar mixture (25 mol%) of paraphenylenediamine (P)/terephthalic acid (T).
A copolyamide was produced at 263°C and ηr2.6. Using an extruder-type melt spinning machine, the copolyamide chips were spun at 295°C with a pore size of 0.5 mm.
After spinning from a spinneret with 30 holes, cooling and solidifying in a conventional manner, and oiling, undrawn yarns of each single filament denier were wound at the spinning speeds shown in Table 1. This is supplied to a stretching machine and stretched and aligned between the feed roller and the first stretching roller (80℃) at a stretching ratio of 1.01, and then between the first stretching roller and the second stretching roller (140℃). The film was hot stretched at a stretching ratio (95% of the cutting stretching ratio) shown in Table 1 while in contact with a heater plate having a length of 50 cm between the ends and the stretching temperature shown in Table 1, and was wound up. For comparison, fibers were obtained by spinning and drawing in the same manner from nylon 66 with a melting point of 265°C and ηr2.8. Table 1 shows the strength and initial Young's modulus of the obtained drawn yarn.

[Table] Example 2 Table 1 was prepared from nylon 66 salt, nylon 6T salt, and a substantially equimolar mixture (PT) of paraphenylenediamine (P)/terephthalic acid (T) using the melt polymerization method with the composition shown in Table 2. Nylon 66 and copolyamide having the properties shown in 2 were obtained. The melt viscosity in the table is the value at the melting point of each polymer +30°C. These polymers were processed using an extruder-type melt spinning machine at the melting temperature shown in Table 2, with a pore diameter of 0.45 mm and a pore number of 30.
After being extruded from a spinneret, cooled and solidified, and oiled, it was taken up by the first roller at 3000 m/min, and then tensioned and aligned between the first and second rollers (100°C) at a draw ratio of 1.03. The film was stretched between the second roller and the third roller at a stretching ratio of 96% of the cutting stretching ratio and then wound up. A heater plate with a length of 150 cm and a temperature of 220° C. was used between the second roller and the third roller. Table 2 shows the yarn properties of the obtained fibers.

【table】 [Brief explanation of the drawing]

Figure 1 is a diagram showing an example of the relationship between spinning speed and strength of drawn yarn, where the solid line is for copolyamide and the dotted line is for nylon.
66 examples are shown.

Claims (1)

[Claims] 1 A copolyamide containing 1 to 50 mol% of aromatic amide units is melt-spun, and after cooling and solidifying, it is spun for 1000 m/s.
1. A method for producing copolyamide fibers, which comprises drawing at a speed of min. min or more, and then hot stretching at a draw ratio of 92 to 98% of the cutting draw ratio at a temperature 100 to 20°C lower than the melting point of the copolyamide.