JPS62299509A - Production of acrylic fiber having high physical property - Google Patents

Abstract

PURPOSE:To obtain a fiber having high strength and modulus by spinning a spinning dope of an acrylonitrile-based polymer at a specific discharge linear velocity ratio, washing the resultant gelatinous filaments with water, drawing and subjecting to dry heat treatment. CONSTITUTION:A spinning dope of an acrylonitrile-based polymer is spun while maintaining the discharge linear velocity ratio defined by the formula at >=4. The resultant spun gelatinous filaments are washed with water, drawn, regulated within the range of an inner water content of 2-20% and heat-treated under tension or drawn while dry-heating at the temperature within + or -30 deg.C of the maximum drawable temperature (about 140-180 deg.C). Thus, the filaments are drawn so that the effective total draw ratio is >=15 times. The concentration of spinning dope is preferably 7-15wt% and discharge linear velocity ratio is preferably 6-12.

Description

DETAILED DESCRIPTION OF THE INVENTION ((a) Industrial Application Field The present invention relates to an industrial method for producing acrylic kettle fibers with high physical properties.

(b) Prior Art 1) In general, there are few uses for fibers that require high strength and high modulus (in recent years, attempts have been made to improve the physical properties of acrylic AI fibers as well.

As one such attempt, as described in JP-A No. 54-134124, fcMi fibers prepared according to a conventional method were further stretched in pressurized steam to achieve high stretching ratio, and finally high Measures to produce physical fibers are being challenged.

Another attempt, as typified by the invention described in Japanese Unexamined Patent Publication No. 59-199809, uses an ultra-high molecular weight polymer as a starting material for fiber formation, and various methods are used for preparing a spinning dope, spinning, etc. This is a means of achieving high physical properties by aligning the polymer molecular chains and making the entire molecular chain approximate to the shape of a so-called extended chain (2), which is extended by t in the fiber axis direction.

(c) Problems to be Solved by the Invention In the pressurized steam used stretching means, there are problems in terms of equipment and operation such as sea μ due to the use of pressurized steam. Although the cohesive force of the nitrile group can be reduced due to the oxidation effect and high-magnification stretching can be achieved, the entire molecular chain is extended and the chain-like Bt
Therefore, as described in the above-mentioned JP-A-Sho, extremely high stretching ratio, preferably 35 to 100 times, is required, and furthermore, in order to bring out the original effect of stretching, The stretching means tends to generate microvoids in the fibers, and these voids become defects, making it difficult to achieve high physical properties.

In addition, in means using ultra-high molecular weight polymers,
It is necessary to prepare a special polymer different from general-purpose polymers, and as the degree of polymerization increases, polymer solubility (
The viscosity of the spinning stock solution increases dramatically, making it difficult to handle the solution, defoaming, spinning, etc. Furthermore, lowering the polymer concentration in the solution to lower the viscosity reduces productivity and the physical properties of the resulting fibers. decreases.

That is, an object of the present invention is to provide an industrial means for producing acrylic fibers having high physical properties without the above-mentioned problems.

B.) Means for Solving the Problems The object of the present invention is to spin an acrylonitrile (hereinafter referred to as AN) polymer spinning dope while maintaining a spout/rotation speed ratio of 4 or more as defined below. Spinning game/I
/ The yarn is washed with water and stretched, and then after the stretching, the internal moisture content of the gel yarn is adjusted to within the range of 2 to 20%, and then subjected to tension dry heat treatment or dry heat stretching under a temperature condition of the maximum stretchable temperature ±60 ° C. ,
This is achieved by increasing the effective total stretching ratio to 15 times or more.

O Vomit aI#i! Speed ratio=- ■ The present invention will be explained in detail below.

First, the hup polymer used in the present invention can be used without any restrictions on molecular weight, etc., as long as it contains 80% by weight or more of AI, preferably 90% by weight or more, and the remaining components As for the known I which can be copolymerized with AN,
X ML form, such as methyl, ethyl, butyl, octyl, methoxyethyl, phenyl of (meth)acrylate,
Ephthyls such as cyclohexyl I; vinylnulfonamides and derivatives thereof such as vinyl acetate, vinyl globionate/I/vinyl butyrate; unsaturated compounds such as (meth)acrylic acid, maleic acid, and itaconic acid; Acids and their salts; Vinyl nulphonic acid, (methaneallyl 7 sulfonic acid, acrylamide propane 7 IL/phonic acid, etc.) and their salts; Vinyl chloride, vinyl bromide/L'N vinyl fluoride, vinylidene chloride, Vinylidene halides and hynylidene hyhalides such as vinylidene bromide; nuthylene, methylhinylketone, methyl levinyl ether, (methanoallylalfur, vinylhylysine, dimethylamine ethyl methacrylate, vinylidene cyanide, methacrylateryl, glycidi/ Examples include vinyl compounds such as I/(meth)7 acrylate.

Solvents for preparing a spinning dope by dissolving such polymers include organic solvents such as dimethylacetamide, dimethylacetamide, and dimethyl urethoxide; rhodan salts such as rhodan soda, rhodan potassium, and p-dan ammonium; nitric acid, and zinc chloride; Inorganic solvents such as aqueous solutions can be mentioned, but in combination with the spinning conditions of the present invention described later, the objects of the present invention can be advantageously achieved, and among these inorganic solvents, an aqueous solution of rhodan salt is preferable. There are no restrictions on the polymer concentration, but from an industrial perspective it is approximately 5.
It is desirable to set the content within the range of 30% by weight, more preferably 7% to 15% by weight.

In the present invention, it is important to perform spinning while maintaining the linear speed ratio of the spinning dope at 4 or more, preferably 5 to 20, more preferably 6 to 12. If the lower limit of this range is exceeded, the drawability will decrease and special drawing operations such as multi-stage drawing in a high boiling point medium of 100°C or higher will not be possible, and the physical properties of the final fiber will deteriorate. You can only get something inferior.

In addition, if the upper limit of this range is exceeded, problems such as the need to deepen the coagulation bath and non-uniformity of physical properties may arise. As long as the discharged yarn is wound up (pulled out) from the coagulation bath, it can be applied not only to the normal wet spinning method, but also to the so-called wet-dry spinning method in which the yarn is discharged into an inert atmosphere such as air and then introduced into the coagulation bath. Can be adopted.

The spun gel yarn pulled out from the coagulation bath is then washed with water and stretched.

For such water washing and stretching steps, cold stretching and hot stretching operations may be performed while or after water washing (solvent removal) according to the conventional method, and both cold and hot stretching can be performed in multiple stages. It is.

In addition, the internal moisture content of the gel/yarn immediately after the stretching process is 150% with respect to 1 iffl of dry fiber-forming polymer.
Hereinafter, it is more preferable to set the moisture content to 130% or less, and examples of means for controlling the moisture content include the polymer concentration in the spinning dope and the temperatures of the coagulation bath, water washing, stretching, etc. In particular, by setting the stretching ratio in the cold/hot stretching step to 10 times or more, preferably 12 to 20 times, taking into account the above discharge linear speed ratio conditions, the moisture content can be advantageously controlled, and finally High physical property fibers can be provided industrially advantageously. Moreover, even among such stretching ratios, even more desirable results can be obtained by adjusting the distribution of cold stretching and hot stretching as described below.

0gA logA+logB fJiI obtained by spinning, washing, and stretching in this way
It is important that the li is then subjected to tension dry heat treatment or dry heat stretching after adjusting the internal moisture content of the stretched yarn to a range of 2 to 20%, preferably 5 to 15%. .

From an industrial perspective, the following methods can be used to adjust the internal moisture content.

After hot stretching, the gel yarn is subsequently stretched (approximately 1.2 times or less) and dried on a PAI: +- wheel to adjust the internal moisture content of the gel yarn within a predetermined range. The temperature of the heating roll should be approximately 140°C or lower, preferably 60°C to 10°C, since rapid drying may cause deterioration of physical properties.
It is desirable to set the temperature at 20°C, more preferably within the range of 70 to 100°C.

Note that when the internal moisture content is outside the range of the present invention, operational problems such as yarn breakage and reduction in drawability are likely to occur particularly in subsequent steps (especially dry heat stretching).

Temperature conditions are particularly important in the tension dry heat treatment or dry heat stretching process, and the temperature is the maximum stretching temperature (the temperature that can give the maximum stretching ratio without causing yarn breakage during dry heat stretching). It is necessary to set the temperature within a range of ±30°C, preferably ±20°C around However, in order to achieve the purpose of the present invention, under such temperature conditions, the fibers that are the object of the present invention cannot be developed.
Preferably 1.1 to 2.5 times, more preferably 1.2 to 2.5 times
It is desirable to carry out dry heat stretching by 2.3 times. In addition, the acrylic fibers produced under the above-mentioned steps and conditions should be such that the final effective total stretching ratio is 15 times or more, preferably 18 times or more, and more preferably 20 times or more. It is necessary to set the stretching conditions, and by satisfying each of these requirements, it is possible to finally produce acrylic fibers with high physical properties without any operational problems and with industrial advantage.

Note that the maximum drawing temperature varies greatly depending on the polymer composition, polymer molecules, spinning conditions, etc.
Although it cannot be mentioned specifically, in the case of a practical polymer composition and molecule E1, for example, AN≧85% by weight, and Mm average molecular ff 7 to 250,000, the temperature changes generally within the range of 140 to 180°C. The exact value of this temperature can be determined, for example, by gradually increasing the dry heat drawing temperature for the test fiber and determining the draw ratio until the fiber breaks under each temperature condition, and then determining the dry heat drawing temperature that gives the maximum draw ratio. You can ask for it.

In this way, approximately 8 g/d or more, preferably 10
Acrylic/vI having a tensile strength of at least 120 g/d, preferably at least 140 g/d.
H-fiber can be made.

(E) Effect The reason why high physical property acrylic fibers can be produced industrially advantageously by combining the above-mentioned process requirements of the present invention is not clear, but it is presumed as follows.

In other words, the desolvation and coagulation rate during spinning under the linear velocity ratio conditions recommended in the present invention improve the molecular groove formation of the polymer in the yarn, resulting in excellent drawing and orientation properties in the subsequent drawing process. It is possible to form it into a state in which it can express a void defect, and subsequent washing and stretching with water, subsequent adjustment of the internal moisture content, and tension dry heat treatment or dry stretching under specific humidity conditions will cause void defects to be formed. It is thought that this contributes to aligning the polymer molecular chains in the finally formed fiber in a state close to that of stretched chains, thereby making it possible to develop high physical properties.

(f) Effects of the invention As mentioned above, it is necessary to prepare a special polymer as a starting material for fiber formation, or to use stretching in pressurized steam, which has problems in terms of equipment, operation, or physical properties. A noteworthy effect of the present invention is that it has provided a means for industrially advantageously producing acrylic fibers with high physical properties without any operational problems.

In addition, since it is not necessary to use a high-viscosity spinning dope in the present invention P, there is no need to use a high-viscosity spinning dope, so there are no handling or operational difficulties in solution, defoaming, spinning, etc., and such difficulties can be avoided. A characteristic advantage of the present invention is that it provides a method that does not cause problems such as lowering the sensitivity of the polymer in the spinning dope and reducing productivity and fiber properties.

(Examples) In order to facilitate understanding of the present invention, examples are shown below, but the scope of the present invention is not limited in any way by the description of such examples. Percentages shown are based on merit unless otherwise specified.

Reference example 1 AN90% and methi acrylate/l/(M A )10
A spinning stock solution with a polymer concentration of 10% (viscosity at 30C: 55 voids) was prepared by dissolving AN Liang Kyongei coalescence (30° C.) consisting of 10% polymer concentration in a Rodan soda aqueous solution of 50% concentration.

Spinning yarn D/H of 80C was passed through a nozzle I with a diameter of 09 mm and 50 holes, and placed in a 15% Rodan soda aqueous solution at -6°C, and the speed ratio of spinning was adjusted as described in the first section above. I changed it and took it up.

Next, the film was cold-stretched to 3.0 times and then hot-stretched in S water to determine the maximum hot-stretching ratio.

The h-absence is shown in Table 1.

This is a lower rate.

From the above table, by increasing the discharge linear speed ratio, the total stretching ratio (maximum stretching ratio that can be stretched without causing yarn breakage)
It is understood that the amount can be significantly increased.

Reference Example 2 Water-swellable gel-like fibers (internal moisture content near 3%) were produced in the same manner as Reference Example 11lls5 except that the hot stretching ratio was 5.3 times.

Next, the test fiber obtained by drying on a heating roller μ at 80°C under a fixed length so that the internal moisture content becomes 10% was
Dry heat stretching was carried out by varying the temperature of the heating roll as shown in the table, and the maximum stretching ratio (dry heat stretching ratio until cutting) at each temperature was determined.

The results are shown in Table 2.

It is understood from the above table that the maximum drawable temperature of one sample fiber is 150°C.

Example 1 The test fiber described in Reference Example 2 (however, the hot drawing ratio was 4 times) was
Eight types of fibers (A
-H) was produced.

Table 6 shows the results of measuring the physical properties of these fibers.

All of these exhibited good operability without causing yarn breakage during dry-heat stretching, but the test samples were undried (internal moisture content 73%) and dried to an internal moisture content of 1%. When the fibers were subjected to dry heat drawing in the same manner as intestine MkD, the fibers were severely broken and could not withstand operation.

From the above table, the fact that the product of the present invention has excellent physical properties, and when the dry heat stretching temperature is outside the range of the present invention, it is inferior to the product of the present invention even if the effective total stretching ratio is the same is 7. The fact that only fibers with physical properties can be obtained is clearly understood.

Example 2 Four types of fibers (
(Eng.-L) were prepared.

Table 4 shows the results of measuring the internal moisture content and final fiber physical properties of these yarns with thermal elongation and IV yarns.

Produced at 3.5 times magnification.

From the above table, one fact is that the product of the present invention has poor physical properties, and the other is the fact that when the discharge linear velocity ratio is out of the range of the present invention (hyoko), the drawability is poor and a fiber with high physical properties cannot be obtained. , clearly understood.

Example 3 The molecule n ((17):1.8) of the AMM copolymer was changed to -1 or the composition of the A N-based copolymer (AN97%
57! Example I
M fibers (M and N) were prepared by straining in the same manner as in AK.

Table 5 shows the results of measuring the physical properties of these m-fibers.

From the upper table of Table 5, it is clearly understood that the product of the present invention has excellent physical properties.

Claims (1)

[Claims] An acrylonitrile polymer spinning stock solution is spun while maintaining a discharge linear velocity ratio of 4 or more as defined below, and the resulting spun gel yarn is washed with water and stretched, and then, after stretching, the gel yarn is After adjusting the internal moisture content within the range of 2 to 20%, tension dry heat treatment or dry heat stretching is carried out under the temperature conditions of the maximum stretchable temperature ± 30 ° C, and the effective total stretching ratio is 15 times or more. A manufacturing method for acrylic fiber with high physical properties. Discharge linear velocity ratio = V_0/V (V_0: Discharge linear velocity of spinning dope (m/min) V: Winding speed of spun gel yarn (m/min))