JPS6278209A - Production of acrylonitrile synthetic yarn - Google Patents

Abstract

PURPOSE:To obtain the titled yarn having improved performance by melt spinning method, by subjecting a specific copolymer of acrylonitrile and another comonomer to melt spinning under a specific condition. CONSTITUTION:A copolymer (0.2-1.0 reduced viscosity etared and 77-110 deg.C glass transition temperature) of 83-92wt% acrylonitrile and 17-8wt% another comonomer (methyl acrylate, n-propyl acrylate, etc.,) is spun at 200-235 deg.C, to give undrawn yarn having <=2.0 half value width beta value at 2theta=17 degrees in wide-angle X-ray diffraction figure. It is drawn to give acrylonitrile synthetic yarn having high crystallizability, high orientation of the polymer in a fiber axis direction, 2-10g/d strength, 5-30% elongation and 50-200g/d modulus of elasticity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing acrylonitrile-based synthetic fibers by melt-spinning a non-hydrated acrylonitrile-based 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, and the fibers can be formed using dimethylformamide, dimethylacetamide, It is carried out by a wet spinning method using a solvent such as dimethyl sulfoxide, nitric acid, aqueous thiocyanate solution, or aqueous zinc chloride solution. Therefore, the spinning speed is 600 m 7 minutes or less, and the spinning speed is 3000 m by melt spinning method for polyester, nylon, etc.
It is necessary to perform spinning at a significantly lower speed than m/min. 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. has been proposed in Japanese Patent Publication No. 59-38243, Japanese Patent Publication No. 59-29525, Japanese Patent Publication No. 47724-1984, 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, it is a copolymer consisting of 50-92% by weight of acrylonitrile and 50-8% by weight of other monomers, and has a reduced viscosity of O, S ~
A method of melt-spinning 1.2 at a temperature of 150 to 250°C to form fibers is disclosed in Japanese Patent Publication Nos. 52-2007 and 4)
It is shown in Publication No. 8-43479 and the like.

Problems to be Solved by the Invention However, the acrylonitrile-based polymer used in these methods is acrylonitrile/methyl acrylate-
The composition is mainly 75/25 (weight ratio), or acrylonitrile/styrene = 65/35
(weight ratio), and although the fibers obtained by melt-spinning these acrylonitrile polymers have high apparent tensile strength, they have a property that their elongation is too high to be used as fibers. Acrylonitrile fibers with the same performance as fibers obtained by wet spinning have not yet been obtained by melt spinning.

Means for Solving the Problems The present inventors conducted studies with the aim of producing acrylonitrile fibers with excellent performance using a melt-spinning method, and found that wide-angle X By specifying the raw material acrylonitrile (IJ) polymer and melt-spinning conditions so that the half-width β value at 2θ = 17° in the line diffraction image is 2.0 or less, it is possible to achieve this objective. Heading The invention has been completed.゛The present invention uses 86 to 92% by weight of acrylonitrile having a reduced viscosity ηred of 0.2 to 1.0 and a glass transition temperature of 77 to 110°C and other copolymerizable comonomers 17
~8% by weight of the copolymer was spun at a temperature of 200 to 265°C, and the half-value width β of 2θ = 17° in the wide-angle X-ray diffraction image was obtained.
This is a method for producing acrylonitrile synthetic fiber, which is characterized by forming an undrawn yarn having a value of 2.0 or less, and then drawing it.

The acrylonitrile copolymer used in the present invention consists of 83-92% by weight of acrylonitrile and 17-8% by weight of five other copolymerizable monomers. Acrylonitrile polymers in which the copolymerized amount of acrylonitrile is less than 83 molecules 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 It is impossible to make an undrawn yarn with a half width β value of 2.0 or less at A wide-angle X-ray diffraction image of a drawn yarn in which the coalescence is oriented and crystallized has a half width β value of 2.0 at 2θ=17°.
It is difficult to obtain fibers with a particle size of 0 or less, and it is not possible to obtain acrylonitrile-based synthetic fibers with good fiber performance. On the other hand, acrylonitrile-based polymers with a copolymerized amount of acrylonitrile of more than 92% by weight lack melting properties when heated at 200 to 265°C, resulting in decreased spinnability from the nozzle and poor shaping into fibers. is not enough. Further, when high temperatures are applied, only the coloring and thermal decomposition of the acrylonitrile polymer are promoted, and no improvement in melt spinning behavior is observed.

Other monomers that can be copolymerized with acrylonitrile include:
By copolymerizing with acrylonitrile at a ratio of 8 to 17% by weight, the resulting acrylonitrile polymer can have a glass transition temperature of 77 to 110°C,
For example, methyl acrylate, ethyl acrylate, n
-propyl acrylate, n-butyl acrylate, n
-octyl methacrylate, n-hexyl methacrylate, vinylidene chloride and the like. Furthermore, the glass transition temperature of the acrylonitrile polymer obtained is 7
Vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, sulfoalkyl acrylate, which are components that can give excellent dyeing properties to fibers at a proportion maintained at 7 to 110 ° C, especially at a proportion of 5% by weight or less, sulfoalkylmethacrylamide and their alkali metal salts, ammonium salts,
Amine salts and the like 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 77°C
If the spinning temperature is less than 200 to 265°C, effective shearing force cannot be applied to the molten copolymer during spinning from the nozzle, and the half width β at 2θ = 17° in the X-ray diffraction image It cannot be an undrawn yarn with a value of 2.0 or less. On the other hand, those whose glass transition temperature is higher than 110℃ are 200~2
Because it does not exhibit good melting properties at a spinning temperature of 65°C,
This does not result in an acrylonitrile polymer with good fiber shaping properties.

The reduced viscosity of the acrylonitrile copolymer used in the present invention (measured at 25°C after dissolving 0.5 F of the acrylonitrile polymer in dimethylformamide IDD ml) is 0.2 to
It needs to be in the range of 1.0. Reduced viscosity is 0.
2 or less acrylonitrile polymer is 200 to 235
Since the melt flowability at ℃ is too high, it is difficult to make an acrylonitrile-based synthetic fiber with good fiber performance. On the other hand, an acrylonitrile polymer having a reduced viscosity of more than 1.0 has poor melt formability at the spinning temperature.

The reduced viscosity of the acrylonitrile-based 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 acrylonitrile with a specific composition and reduced viscosity) I
1 is a graph showing the relationship between a J-type polymer, its melt-spinning properties, and the region where the half-width at 2θ=17° is 2.0 in a wide-angle X-ray diffraction image of a drawn yarn obtained by melt-spinning. The ◎ mark in the diagram indicates the melt index (hereinafter referred to as M) value 10
Above, ○ mark is above MIβ value, X mark is below MIβ value, ××
The mark indicates MIβ value 0 point. The MI value is calculated by heating the acrylonitrile polymer to 230℃, diameter 2cm, length f3t.
It means the weight (9) of the acrylonitrile-based polymer discharged in 10 minutes when extruded from a nozzle of rar with a load of 5 kII. The lower left side of the curve in the figure is the melting region, and the MI value of the acrylonitrile-based polymer in this region is 5 or more, and exhibits good melt spinnability at a spinning temperature of 200 to 235°C. Note that if the MI value is too high, the viscosity of the acrylonitrile polymer when heated to 200 to 235°C tends to be extremely low, and the melt spinning operability tends to be extremely poor. Therefore, it is preferable that the reduced viscosity is 0.2 (linear BC) or more and the MI value is 200 or less, particularly 170 or less. The region to the right of the straight line AB is a crystal development region, and by spinning an acrylonitrile polymer having a composition within this region at 200 to 235°C and then stretching it, the wide-angle X-ray diffraction image shows 20=
A fiber having a half width β value at 17° of 2.0 or less is obtained. A drawn yarn with a half width β value of 2.0 or more lacks the formation of a crystal structure in the fiber structure, resulting in insufficient strength and excessive elongation, resulting in a fiber with good performance. do not have. Furthermore, the acrylonitrile polymer located in the region to the right of the straight line CD has a markedly reduced melting characteristic at 200 to 260°C, and is likely to cause thermal decomposition and thermal coloring.

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 type polymer is low, and the melt formability of the acrylonitrile type polymer is lowered. Two acrylonitrile polymers with the above properties
The undrawn yarn obtained by melt spinning at a temperature of 00 to 235°C has a half width β value of 2.0 or less in a wide-angle X-ray diffraction image 2θ = 17°, and is highly crystalline. . Wide-angle X-ray diffraction images of undrawn yarns If the half width β value at 2θ = 17° is larger than 2.0, the crystallinity of the drawn yarns can be increased in the subsequent drawing using any drawing method. In other words, the half width β value at 2θ=17° is 2
．． It cannot be less than 0, and it is not possible to obtain an acrylonitrile non-synthetic fiber with well-balanced strength and elongation.

Then, the obtained undrawn yarn is drawn to obtain the acrylonitrile synthetic fiber of the present invention.

- As a method for stretching the undrawn yarn, a submersible 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, an undrawn yarn obtained by melt-spinning an acrylonitrile polymer has a wide-angle X-ray diffraction image 2θ=1
Since the half width β value at 7° is 2°0 or less, by drawing this undrawn yarn, the crystallinity and orientation of the polymer in the fiber axis direction are further increased, and the strength is 2~2°.
1011/d, elongation 5-30% and elastic modulus 50-200
A well-balanced acrylonitrile synthetic fiber having a ratio of 9/d is obtained.

Further, according to the method of the present invention, the yarn winding speed is 1000 m
High speed spinning of 7 minutes or more, especially 2000 m/min or more is also possible.

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 emulsifier, 5 parts of potassium persulfate, and lauryl mercaptan.
500 parts of a mixture of acrylonitrile (AN) and methyl acrylate (MA) in the proportions shown in the table was added dropwise to the polymerization tank and polymerized at 55°C for 6 hours. The obtained latex containing an acrylonitrile polymer 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 to 230℃, nozzle hole diameter 0.3φ, L/
D = 150 using a 0.2.72-hole nozzle
Melt spinning was carried out at a spinning speed of 0 m7 minutes, the resulting undrawn yarn was wound up once, and the spinnability at 230°C and the wide-angle X-ray diffraction image of the undrawn yarn were measured for the half-width β value at 2θ = 17°. did. The results are shown in Table 1. Then experiment number 1.4.6
．． The undrawn yarns of Nos. 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 20=
It is known that a fiber with good properties cannot be obtained unless the half width β value at 17° is 2.0 or less.

[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] Acrylonitrile 83-92 having a reduced viscosity ηred of 0.2-1.0 and a glass transition temperature of 77-110°C
A copolymer of 17% to 8% by weight of other copolymerizable comonomers was spun at a temperature of 200 to 235°C, and a wide-angle
A method for producing an acrylonitrile-based synthetic fiber, which comprises forming an undrawn yarn having a half width β value of 2θ=17° in a line diffraction image of 2.0 or less, and then stretching the fiber.