JPS61282418A - Method for drawing acrylic fiber - Google Patents

Abstract

PURPOSE:To obtain acrylic fibers having high-degree molecular orientation and showing improved physical properties, by drawing acrylic fiber yarns coagulated in a coagulating beth in a drawing bath under specific conditions. CONSTITUTION:Acrylic fiber yarns coagulated in a coagulating bath are drawn under conditions of <=0.3, preerably <=0.1 DELTAx and >=10, preferably 30-10,000 D expressed by the formula [D is a drawing factor; V2 is the running linear velocity (m/min) of the yarns after drawing;V1 is the running linear velocity (m/min) of the yarns before drawing; x is the effective distance during drawing]. Normally, V1 is set within 0.3-200m/min range, and V2 is set within 3-1,000m/min range. Thus, the drawing can be efficiently carried out and the apparatus can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for drawing acrylic fibers. More specifically, the present invention relates to a method for producing acrylic fibers using a wet spinning method, by effectively carrying out stretching, highly arranging molecules, and obtaining fibers having excellent physical properties.

Conventional Technology When producing acrylic fibers using a wet spinning method, the yarn coagulated in a coagulation bath is usually stretched by two to several times in a drawing bath in order to arrange the molecules and improve physical properties. In normal cases, the length of the drawing bath is in the range of 0.5 to several meters, and the degree of drawing is determined by the ratio of the running linear speed of the yarn before drawing to the running linear speed of the thread after drawing (drawing ratio). It is usually determined by

Recently, with the diversification of consumer needs, acrylic fibers have come to be required to have excellent physical properties, such as more durable Wi-fibers and high-strength fibers. In order to improve the physical properties, stretching is usually carried out by employing a wet spinning method, and a more effective method is to improve the arrangement of molecules than to perform this stretching efficiently.

Problems to be Solved by the Invention In view of the current situation, the inventors of the present invention have made extensive studies and have developed an extremely efficient method by precisely controlling the stretching conditions used to improve physical properties. We have now established a method for arranging molecules.

The fibers obtained by the method of the present invention are characterized by having an extremely high degree of molecular alignment and exhibiting excellent physical properties.

Means for Solving the Problems In the present invention, when producing acrylic fibers by a wet spinning method, a filament coagulated in a coagulation bath is processed in a drawing bath using the following formula: D= (V2-Vl)/△X D: Stretching factor, v2: Running linear velocity of yarn after stretching (m/
min) ■1; Running linear velocity (m/min) Δx on the yarn before drawing;
This method of drawing acrylic fibers is characterized in that the drawing is carried out under the conditions that ΔX of the effective distance between drawings (In) is 0.3 or less and D is 0 or more.

The composition of the stretching bath consists of a polymer solvent and a coagulant, and the concentration of the solvent in the solution must be 75 times or more the lower limit concentration (weight fraction) of the solvent that dissolves the polymer. preferable. The composition of the coagulation bath consists of a polymer solvent and a coagulant, and the concentration of the solvent in the solution must be at least 0.75 times the Ik weight fraction of the solvent that dissolves the polymer. Conventionally, when producing acrylic edge ## by a wet spinning method, in order to maintain fiber performance, the yarn coagulated in one coagulation bath is stretched twice to several times in a drawing bath, It is common to arrange molecules.

This method for orienting molecules is generally carried out by stretching by varying the speed χ between stretching rollers installed in a stretching bath.

The manufacturing guideline for determining the molecular arrangement is determined by the ratio of the running linear speed of the yarn between the drawing rollers (drawing ratio).

However, as a result of intensive study of the stretching conditions, the present inventors found that conventional stretching conditions have a limit in promoting molecular orientation.

Efficiency (in order to carry out drawing, the length of the drawing bath must be shortened, more precisely the distance from when the yarn starts to change until it ends (in the present invention, the effective drawing distance △ In addition, it is not appropriate to define the drawing effect by the ratio of the running linear velocity of the yarn between the drawing rollers (drawing ratio) as in the past. It was concluded that it is preferable to define it based on the stretching factor described above.

That is, the present invention is carried out by using a short stretching bath of 3 m or less for stretching, which was conventionally carried out using a stretching bath with Δx of 0.5 m to several meters.

Δx is defined as the distance from the point where the yarn begins to deform to the point where the deformation ends. In the method of the present invention, Δx is usually set to 0.6 or less, preferably 0.6 or less.
It is set to 2 or less, more preferably 0.1 or less. If Δx is too thick (if the molecules are not oriented sufficiently, it will not be possible to obtain a fiber with excellent physical properties.In order to ensure sufficient molecular alignment, the trap is set, and Δx will not cause manufacturing troubles such as thread breakage. It is preferable to keep it as small as possible.

Furthermore, in the method of the present invention, the stretching factor of D is usually set to be 10 or more in order to achieve suitable molecular orientation. It is preferably set to a value of 30 to 10,000, but the upper limit is not limited to this range.

vl and v2 are not particularly limited, but usually v1
is 0.3″-” 200-/min% v2 is 6-1
000m/min range.

The spinning dope used in the method of the present invention is an acrylonitrile polymer or an acrylonitrile copolymer having an M ratio of 50 or more, dimethylformamide (DMIP), dimethylacetamide (D
MAC), dimethyl sulfoxide (DMSO), a nitric acid aqueous solution, a zinc chloride aqueous solution, a rhodan salt aqueous solution, or the like dissolved in a solvent is used. Usually, the weight fraction of the acrylonitrile polymer or acrylonitrile copolymer in the solvent is 10-4011. In the method of the present invention, this spinning dope is extruded into a coagulation bath, pulled up, and immediately stretched in a stretching bath. The concentration of the coagulation bath is not limited to %, but should be set so as to obtain a suitable orientation of molecules in the drawing bath, and the concentration of the coagulation bath in which conventional spinning is performed is used. However, it is preferable to use a concentration at which the coagulated filament remains in a fluid state.

The coagulation bath is composed of a polymer solvent and a coagulant, and the concentration of the solvent in the solution is 0.00000000000000000000000000000000000000000000000000.
The density is set to 75 times or more. Here, the lower limit concentration of the solvent is defined as the minimum 1f1 fraction of the solvent in the solution required to dissolve the polymer when the polymer is dissolved in a solution composed of a solvent and a coagulant. When considering industrial productivity, the coagulation bath is generally an aqueous solution obtained by adding water to the solvent used to prepare the spinning material. To do this, monohydric alcohols such as methanol, ethanol, propatool,
A solution of polyhydric alcohol such as ethylene glycol or chrycerin may be used, or a sixth component may be added.

For example, if nitric water #liquid is used in the coagulation bath, 68~
501 aqueous solution is a dimethylformamide aqueous solution,
In the case of dimethylacetamide aqueous solution and dimethyl sulfoxide aqueous solution, 65-90! When the aqueous solution is a Rodan salt aqueous solution or a zinc chloride aqueous solution, an aqueous solution of 20 to 401 It is preferably used. Furthermore, when considering the fluidity of the coagulated filament, the residence time of the filament in the coagulation bath should be within 60 seconds, preferably 0.5 to 60 seconds.

Further, the temperature of the coagulation bath is usually set within the range of -5 to 90°C.

In the method of the present invention, the coagulated filament taken up from the coagulation bath is drawn under the conditions described above.

At this time, the same aqueous solution as the coagulant used in the coagulation bath is generally used in the drawing bath, but other solutions or a sixth component may also be added to increase the drawability. be. Although the concentration of the stretching bath is not particularly limited, it is preferably set within the same concentration range as that of the coagulation bath, which is effective for improving the orientation of molecules. The temperature of the drawing bath requires detailed consideration in order to provide a suitable temperature for molecular orientation, but a temperature range of -5 to 90°C is usually used. This stretching is not limited to 9 stretches at a time (in addition, multi-branched stretching may be performed to further increase the molecular orientation, and conventional stretching may also be combined.
In some cases, 1J11 may be stretched in the air with a solution having the same composition as that of the stretching bath attached or impregnated without using the stretching bath for a long time.

The fibers produced by the method of the present invention are subjected to a normal water washing treatment, and the amount of residual solvent is reduced to 0.0000000000000000 yen, based on the weight of the fibers.
Remove to less than 1%. Furthermore, in order to increase physical properties such as strength, it may be re-stretched in hot water or steam. Additionally, dry under tension or under tension to remove moisture.

Next, heat treatment 7 is performed to increase stability. The heat treatment is carried out under a heated atmosphere such as in pressurized steam, hot air, hot water, or on a hot plate.

The method of the present invention is not limited to the production method of acrylic I & fiber, but when a wet method is adopted to produce fiber,
For example, it can be used to stretch regenerated cellulose, aramid fibers, etc.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.〇Example 1 Acrylotritrile 91.5% by weight, methyl acrylate 8%
A copolymer containing 0.5 weight percent of sodium methallylsulfonate was dissolved in a 67N aqueous solution of nitric acid at OOC, and a spinning stock solution of 16 weight percent was prepared.

Next, this stock solution was extruded into a coagulation bath using a nozzle with a hole diameter of 0.7 mm and a number of holes of 100 at a rate of 0.5 m/nip.
pulled up at a speed of The coagulation bath at this time was composed of an aqueous solution of 42% nitric acid, and the temperature was 5°C. Further, the residence time of the filamentous coagulation bath was 8 seconds.

Subsequently, stretching was carried out in a stretching bath at a bath temperature of 50° C., which was made up of 42) nitric acid aqueous bath solution. At this time Δx is 0.
05, vl was 0.5, and V2 was 5. After completing the stretching, the rutted fibers were washed with water and thoroughly dried in hot air at 130°C.
Thermal relaxation treatment was performed in 0'O water vapor.

Can we use a polarizing microscope to evaluate the molecular arrangement of these Ni fibers? was used to measure the birefringence. The measurements were performed assuming that the fiber was circular and removing the influence of morphological birefringence. the result,
Δn of the obtained fibers = -0,00492 (average for 10 fibers), 8111 of the acrylic Isi fibers produced using the commercially available nitric acid T# agent = -0,0035, The absolute value was higher than that of No. 2, indicating good molecular orientation.

The strength of this fiber was 8.09/d and the elongation was 28%.

Example 2 Copolymerization of 7 liters of lonitrile, 8 parts by weight of methyl acrylate, 0.5 parts by weight of sodium methallylsulfonate, dissolved in 100% dimethylformamide at 25°C, and 16N A spinning stock solution χ was prepared.

Next, using this ii'v nozzle with a hole diameter of 0.7 m x φ and a number of holes of 100, it was extruded into a coagulation bath at a rate of 0.5 m /
It was pulled up at a speed of min. The coagulation bath at this time was composed of an 801% dimethylformamide aqueous solution, and the temperature was 25%.
It was °C. Further, the residence time of the filamentous coagulation bath was 10 seconds. Subsequently, stretching was carried out in a stretching bath at a bath temperature of 60° C., which was composed of a dimethylformamide aqueous solution of 80 ml. At this time, Δx is 0-08, vl is O-5,
■2 is 6 and ivy. After washing the stretched SL fiber with water, 1
It was thoroughly dried in hot air at 30°C and subjected to heat relaxation treatment in steam at 120°C.

The m-fibers had a mu D of -0, [) 048 A, indicating good molecular orientation. Also, the tensile strength is ・7.5 jj
/d.

The tensile elongation was 60 inches.

Example 3 Acrylonitrile 91. s weight s, methyl acrylate 8
A copolymer of 0.5M sodium methallylsulfonate was dissolved in 100'l dimethylacetamide at 25°C to prepare a 16% by weight spinning stock solution χ.

Next, this stock solution was extruded into a coagulation bath using a nozzle with a hole diameter of 0.7 mm and a number of holes of 100 at a rate of 0.5 m/min.
pulled up at a speed of The coagulation bath at this time was composed of an 80% dimethylacetamide aqueous solution, and the temperature was 25°C.
Met. ``The residence time of the filamentous coagulum in the bath was 10 seconds. Subsequently, stretching was carried out in a stretching bath containing an aqueous dimethylacetamide solution of 80% by weight and having a bath temperature of 60°C. At this time, △X is 0.1, vl is 0.5, and v2 is 4.
It was 5. After the stretched fibers were washed with water, they were sufficiently dried in hot air at 160°C and subjected to thermal relaxation treatment in steam at L20'C. This fiber had a Δn of -0,00455.

Example 4 Acrylonitrile 91.5mi%, methyl acrylate s
A copolymer containing 0.5% by weight of sodium methallylsulfonate was dissolved in 100% dimethyl sulfoxide at 25° C. to prepare a spinning stock solution for a 16N kettle.

Next, this stock solution was extruded into a coagulation bath at 0.5 i/min using a nozzle Z with a hole diameter of 0.7 nm and 1100 holes.
pulled up at a speed of The coagulated W bath at this time was composed of an 82N dimethyl sulfoxide aqueous solution, and the temperature was 25°C.
It was C. Further, the residence time of the filamentous coagulation bath was 13 seconds. Subsequently, seven stretching operations were carried out in a stretching bath containing a dimethyl sulfoxide aqueous solution of 85% by weight and having a bath temperature of 60°C. At this time, Δx is 0.1, vl+-! 0.5, v2
was 5. Low elongation l completed * kn w After washing with water, 1
It was thoroughly dried in hot air at 30°C and subjected to thermal relaxation treatment in steam at 120°C. Δn of this twill fiber is -0,00461
Met.

Comparative Example 1 Acrylonitrile 91.5% by weight, methyl acrylate 8%
A copolymer of 0.5 ml of sodium methallylsulfonate and 0.5 ml of sodium chloride was dissolved in an aqueous solution of 671 nitric acid at 0°C.
A 6% by weight spinning stock solution was prepared.

Next, this stock solution was extruded into a coagulation bath using a nozzle with a hole diameter of 0.7RIIIφ and a number of holes of 100 at a rate of 0.5 i/mi.
It was pulled up at a speed of n. The coagulation bath at this time was composed of a 42% by weight nitric acid aqueous solution, and the temperature was 5°C. Further, the residence time of the filamentous coagulation bath was 10 seconds. Continuing, 4゛2
Stretching was carried out in a stretching bath at a bath temperature of 50° C., which was composed of a weight-related nitric acid water bath solution. This △x is 0.8, vl is O-5
,■2 is 5 and ivy. After the fibers have been stretched and washed with water, 1
It was thoroughly dried in hot air at 50°C and subjected to thermal relaxation treatment Z in steam at 120°C. △n of this Wji fiber is -0,0
Effects of the Invention According to the method of the present invention, it is possible to carry out the conventional stretching process more efficiently, and the equipment can be made more compact. Fiber manufacturing equipment can be downsized and equipment investment can be reduced. In addition, the twill rods obtained by the method of the present invention have good molecular alignment and excellent physical properties. You can expect to have it.

Claims (3)

[Claims] (1) When producing acrylic fibers by the wet spinning method, the filament coagulated in a coagulation bath is subjected to the following formula in a drawing bath: D=(V_2-V_1)/Δx D=drawing factor, V_2: yarn after drawing Running linear velocity of the strip (m
/min) V_1: linear velocity of the yarn before drawing (m/min) Δx; effective distance between drawings (m) Δx is 0.3 or less and D is 10 or more. How to draw acrylic fibers (2) The composition of the drawing bath consists of a polymer solvent and a coagulant,
The stretching method according to claim 1, which uses a stretching bath in which the concentration of the solvent in the solution is 0.75 times or more the lower limit concentration (weight fraction) of the solvent that dissolves the polymer. (3) The composition of the coagulation bath consists of a polymer solvent and a coagulant,
The stretching method according to claim 1, which uses a coagulation bath in which the concentration of the solvent in the solution is 0.75 times or more the lower limit concentration (weight fraction) of the solvent that dissolves the polymer.