JPH0133566B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing acrylonitrile synthetic fibers by melt spinning a non-hydrated acrylonitrile polymer. Conventional technology Acrylonitrile polymers copolymerized with 70% by weight or more of acrylonitrile are non-thermoplastic polymers, so they cannot be shaped into fibers by melt spinning. dimethyl sulfoxide, nitric acid,
It is carried out by a wet spinning method using a solvent such as a thiocyanic acid aqueous solution or a zinc chloride aqueous solution. Therefore, the spinning speed is 300 m/min or less, which is significantly lower than the spinning speed of 3000 m/min or more by the melt spinning method for polyester, nylon, etc.
Further, since a large amount of energy is required for recovering the solvent used in the spinning process, drying the obtained fibers, etc., it is difficult to reduce the manufacturing cost of acrylic fibers using the wet spinning method. Technological development of melt spinning methods for acrylonitrile-based polymers has been progressing for some time. For example, since acrylonitrile-based polymers exhibit thermoplasticity when hydrated, methods for preventing melting of hydrated acrylonitrile-based polymers have been developed. is Special Publication No. 59-38243,
It has been proposed in Japanese Patent Publication No. 59-29525, Japanese Patent Publication No. 59-47724, etc. However, these melt spinning methods have the disadvantage that voids are likely to occur in the yarn structure during the process in which water rapidly escapes from the yarn discharged from the nozzle, making it difficult to obtain fibers with uniform performance. On the other hand, a method in which a copolymer consisting of 50 to 92% by weight of acrylonitrile and 50 to 8% by weight of other monomers with a reduced viscosity of 0.5 to 1.2 is melt-spun at a temperature of 150 to 250°C to form fibers. is shown in Japanese Patent Publication No. 52-2007, Japanese Unexamined Patent Publication No. 48-43479, etc. Problems to be Solved by the Invention However, the acrylonitrile polymers used in these methods mainly have a composition of acrylonitrile/methyl acrylate = 75/25 (weight ratio), or acrylonitrile/methyl acrylate = 75/25 (weight ratio). Styrene = 65/35 (weight ratio),
Although the fibers obtained by melt-spinning these acrylonitrile polymers have high apparent tensile strength,
The elongation of acrylonitrile fibers is too high to be used as fibers, and it has not yet been possible to obtain acrylonitrile fibers with the same performance as fibers obtained by wet spinning methods using melt spinning methods. Means for Solving the Problems As a result of studies aimed at producing acrylonitrile fibers with excellent performance using a melt-spinning method, the present inventors found that wide-angle X The present invention was completed by discovering that the objective could be achieved by specifying the raw material acrylonitrile polymer and the melt spinning conditions so that the half width β value at 2θ = 17° in the line diffraction image was 2.0 or less. did. The present invention provides acrylonitrile having a reduced viscosity ηred of 0.2 to 1.0 and a glass transition temperature of 77 to 110°C.
83~92% by weight and 17~ other copolymerizable comonomers
A copolymer with 8% by weight is spun at a temperature of 200 to 235°C at a winding speed of 1000 m/min or more, and the unstretched product has a half width β value of 2θ = 17° in a wide-angle X-ray diffraction image of 2.0 or less. It is characterized by being made into a yarn and then drawn.
This is a method for producing acrylonitrile-based fibers. The acrylonitrile copolymer used in the present invention consists of 83 to 92% by weight of acrylonitrile and 17 to 8% by weight of other copolymerizable monomers.
Acrylonitrile polymers with a copolymerized amount of acrylonitrile of less than 83% by weight have good melting properties, but the orientation of the polymer in the fiber axis direction during melt spinning is insufficient, and the X-ray diffraction image 2θ = 17° Undrawn yarns with a half width β value of 2.0 or less cannot be obtained, and such undrawn acrylonitrile fibers with a large half width β value cannot be drawn because the polymer is sufficiently oriented in the fiber axis direction. The wide-angle X-ray diffraction image of the crystallized product, that is, the stretched system, has a half-width β value of 2.0 at 2θ = 17°.
It is difficult to make the following fibers, and it is impossible to make acrylonitrile-based synthetic fibers with good fiber performance. On the other hand, the copolymerization amount of acrylonitrile is 92% by weight.
More acrylonitrile-based polymers are 200-235
When heated at ℃, the melting properties are insufficient, the spinnability from the nozzle is reduced, and the ability to form into fibers is insufficient. Furthermore, when the temperature is increased, the coloration and thermal decomposition of the acrylonitrile polymer are only promoted, and no improvement in melt spinning behavior is observed. Other monomers that can be copolymerized with acrylonitrile include those that can be copolymerized with acrylonitrile at a ratio of 8 to 17% by weight to make the resulting acrylonitrile polymer have a glass transition temperature of 77 to 110°C. Examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, n-octyl methacrylate, n-hexyl methacrylate, and vinylidene chloride. Furthermore, vinyl sulfonic acid, styrene sulfonic acid, and allyl sulfone, which are components that can give excellent dyeing properties to fibers, are used in proportions that maintain the glass transition temperature of the resulting acrylonitrile polymer at 77 to 110°C, especially in proportions of 5% by weight or less. Acids, methallyl sulfonic acid, sulfoalkyl acrylate, sulfonalkyl methacrylate, sulfoalkyl methacrylamide, and alkali metal salts, ammonium salts, amine salts, etc. thereof can also be used. In this case as well, the total amount of monomers other than acrylonitrile must be 8 to 17% by weight. The glass transition temperature of acrylonitrile copolymer is
If the spinning temperature is lower than 77℃, it is impossible to apply effective shearing force to the molten copolymer during spinning from the nozzle, and the half value at 2θ = 17℃ in the X-ray diffraction image Undrawn yarn with a β value of 2.0 or less cannot be used. On the other hand, an acrylonitrile polymer having a glass transition temperature higher than 110°C does not exhibit good melting properties at a spinning temperature of 200 to 235°C, and therefore does not provide an acrylonitrile polymer with good fiber shaping properties. Reduced viscosity of the acrylonitrile copolymer used in the present invention (measured at 25°C after dissolving 0.5 g of acrylonitrile polymer in 100 ml of dimethylformamide)
must be in the range of 0.2 to 1.0. Acrylonitrile polymers with reduced viscosity of 0.2 or less are
Since the melt fluidity at 200 to 235°C is too high, it is difficult to make an acrylonitrile-based synthetic fiber with good fiber performance. On the other hand, acrylonitrile polymers with a reduced viscosity exceeding 1.0 have poor melt formability at the spinning temperature. The reduced viscosity of the acrylonitrile polymer can be adjusted by increasing or decreasing the amount of the molecular weight regulator added during the polymerization reaction. As the molecular weight regulator, for example, n-lauryl mercaptan, n-octyl mercaptan, etc. are used. The drawing shows an acrylonitrile polymer having a specific composition and reduced viscosity, its melt spinning properties, and a wide-angle X-ray diffraction image 2θ of a drawn yarn obtained by melt spinning.
It is a graph showing the relationship with the region where the half width at 17° is 2.0. In the figure, ◎ indicates a melt index (MI) value of 10 or more, ○ indicates an MI value of 5 or more, ×
The mark indicates a point with an MI value of 3 or less, and the XX mark indicates a point with an MI value of 0.
The MI value is calculated by heating the acrylonitrile polymer to 230°C and applying a load of 5 through a nozzle with a diameter of 2 mm and a length of 8 mm.
It means the weight (g) of acrylonitrile-based polymer discharged in 10 minutes when extruded by applying Kg. The lower left side of the curve AD in the figure is the melting region, and the MI of the acrylonitrile polymer in this region is
The value is 5 or more, indicating good melt spinnability at a spinning temperature of 200 to 235°C. Furthermore, if the MI value is too high,
When heated to 200 to 235°C, the viscosity of the acrylonitrile polymer becomes extremely low, and melt spinning operability tends to become extremely poor. The reduced viscosity is then 0.2 (linear BC) or more, and the MI value is
It is preferably 200 or less, particularly 170 or less. The region to the right of the straight line AB is the crystal expression region,
Acrylonitrile polymers with compositions within this range
By spinning at 200-235℃ and then stretching,
The half-width β value at 2θ=17° of the wide-angle X-ray diffraction image is
Fibers below 2.0 are obtained. This half width β value is 2.0
Since the above-mentioned undrawn yarn lacks the formation of a crystal structure in the fiber structure, the strength is insufficient and the elongation is excessive, so that it cannot be a fiber with good performance. Furthermore, the acrylonitrile polymer located in the region to the right of the straight line CD has a significantly reduced melting characteristic at 200 to 230°C, and is likely to cause thermal decomposition and thermal coloration. In carrying out the present invention, an acrylonitrile polymer having the above characteristics is spun at a temperature of 200 to 235°C. If the spinning temperature is higher than this, a thermal decomposition reaction of the acrylonitrile polymer is likely to occur.
On the other hand, if the spinning temperature is lower than this, the melt formability of the acrylonitrile polymer will decrease. The acrylonitrile polymer having the above characteristics is rolled up at a temperature of 200 to 235°C at a speed of 1000 m/min or more, preferably 2000 m/min.
The undrawn yarn obtained by melt spinning at m/min or more has a half width β value of 2.0 or less at 2θ=17° in a wide-angle X-ray diffraction image, and is highly crystalline. A wide-angle X-ray diffraction image of an undrawn yarn whose half-width β value at 2θ=17° is larger than 2.0 means that the crystallinity of the drawn yarn is increased in the subsequent drawing, no matter what drawing method is used, that is, 2θ The half width β value at =17° cannot be less than 2.0,
Acrylonitrile synthetic fibers with well-balanced strength and elongation cannot be produced. Then, the obtained undrawn yarn is drawn to obtain the acrylonitrile synthetic fiber of the present invention. As the stretching method for the undrawn yarn, a boiling water stretching method, a steam stretching method, a dry heat stretching method, etc. can be used. Effects of the Invention According to the method of the present invention, the undrawn yarn obtained by melt-spinning an acrylonitrile polymer has a half width β value of 2.0 or less in a wide-angle X-ray diffraction image 2θ=17°. By stretching this undrawn yarn, the crystallinity and orientation of the polymer in the fiber axis direction are further increased, and the strength is 2 to 10 g/d and the elongation is 5 to 30 g/d.
% and elastic modulus of 50 to 200 g/d. Parts in the following examples mean parts by weight. Example 1 A polymerization tank was charged with 1000 parts of deionized water, 10 parts of an emulsifier, 5 parts of potassium persulfate, and lauryl mercaptan, and 500 parts of a mixture of acrylonitrile (AN) and methyl acrylate (MA) in the proportions shown in Table 1 was added. Polymerization was carried out at 55° C. for 6 hours while dropping the mixture into a polymerization tank. The obtained acrylonitrile polymer-containing latex was coagulated by a conventional method, separated, washed, and then dried. Table 1 shows the glass transition temperature (Tg) and reduced viscosity of the obtained acrylonitrile polymer. This polymer was heated at 230℃, nozzle hole diameter 0.3φ, L/
D = 0.2, melt-spun at a spinning speed of 1500 m/min using a 72-hole nozzle, and the resulting undrawn yarn was wound once to determine spinnability at 230°C and wide-angle X-ray diffraction image 2θ of the undrawn yarn. The half width β value at =17° was measured. The results are shown in Table 1. Next, the undrawn yarns of Experiment Nos. 1, 4, 6, 7, and 8 were drawn by the method shown in Table 2. The properties of the obtained drawn yarn are shown in Table 2. From this, the half width β value at 2θ=17° is
It is known that fibers with good properties cannot be obtained unless the coefficient is 2.0 or less.

【table】

【table】 [Brief explanation of drawings]

The drawing is a graph showing the relationship between the composition and reduced viscosity of an acrylonitrile-based polymer, spinnability, and crystallinity.

Claims (1)

[Claims] 1 83-92% by weight of acrylonitrile having a reduced viscosity ηred of 0.2-1.0 and a glass transition temperature of 77-110°C and 17-8% by weight of other copolymerizable comonomers
Winding speed of 1000 at a temperature of 200 to 235℃
2θ in the wide-angle X-ray diffraction image after spinning at m/min or more.
A method for producing acrylonitrile-based synthetic fibers, characterized by forming an undrawn yarn having a half width β value of 2.0 or less at =17°, and then drawing it.