JPS61119709A - Production of acrylic fiber having excellent fiber property - Google Patents

Abstract

PURPOSE:To produce the titled fiber suitable as an industrial fiber material or a reinforcing fiber material for substituting asbestos, etc., by carrying out the dry and wet spinning of a solution of an acrylonitrile polymer having high intrinsic viscosity and high polymerization degree, and drawing the obtained fiber under specific dry heat condition. CONSTITUTION:A solution of an acrylonitrile polymer having an intrinsic viscosity of >=2.0 and having high polymerization degree is subjected to the dry and wet spinning and then to the primary drawing usually preferably to a draw ratio of 4-8. The drawn fiber is drawn again to the total draw ratio of >=10, preferably 15-20 at preferably 160-220 deg.C in dry state under a condition to develop the raw tension of >=1.0g/d. The objective fiber preferably having a tensile strength of >=12g/d, an elastic modulus of >=200g/d and a knot strength of >=2.5g/d can be produced. The hot dry drawing can be carried out by passing the fiber through a hot cylinder maintained at a specific temperature to enable the hot-drum drawing of the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is applicable to fiber physical properties such as tensile strength and elastic modulus as well as other m! The present invention relates to a method for producing acrylic fibers that have significantly superior fiber physical properties in terms of navy blue performance, compared to conventional acrylic fibers.

More specifically, the present invention allows acrylic 11i fibers, which have conventionally been used mainly for clothing, to be widely used as industrial or industrial m-screen floor materials and reinforced or reinforced uA screen materials due to their excellent fiber properties. This invention relates to a method for producing acrylic GI material having high fiber properties.

(Conventional technology) Conventionally, acrylic! Although 1il(t) has excellent properties not found in other synthetic fibers, such as light resistance and dyeability, it has low mechanical strength and is used for clothing and interior decoration such as carpets and curtains. is the center,
It is not used for so-called reinforcement purposes.

Recently, asbestos, which has been used to reinforce cement, has been legally banned or restricted due to its carcinogenic properties. Acrylic fibers have attracted attention because of their good properties, and are being used as fibers to replace asbestos (for example, JP-A-57-170869).

However, the above asbestos 1-generation Pg 1M If
Acrylic fibers, which have been proposed as It could not be said that it had been improved.

The present inventors have discovered that the degree of polymerization of this ridge-like structure is significantly higher than that of acrylonitrile polymers (hereinafter referred to as ΔN polymers) that have been previously used in conventional acrylic fibers for clothing. By using an AN-based polymer and applying a specific spinning method of dry/wet spinning, it has excellent strength, elastic modulus, and other fiber properties, making it practical as the above-mentioned reinforcing fiber. We found and proposed an acrylic fiber that satisfies Ii.

The present inventors have discovered the present invention by conducting extensive research into the method for producing acrylic fibers proposed above. In other words, the sea urchin acrylic type I! described in JP-A No. 48-45623! In the production of Ii navy blue, in order to improve the mechanical strength of the fiber, ΔN
Although it is thought that if a polymer with a high degree of polymerization is used as a system polymer, it is possible to greatly increase the draw ratio compared to a polymer with a low degree of polymerization, in reality, the drawability decreases and mechanical There is a problem that the direction of strength cannot be determined. In order to solve this problem of low drawability, the invention described in JP-A-Sho proposes a method in which the densified fibers are drawn under a specific drawing tension in a specific pressurized steam.

However, in the wet spinning method proposed in the above-mentioned JP-A-Sho, even if it is possible to spin an AN-based polymer with a high degree of polymerization, the degree of polymerization is limited to 2.3 expressed in terms of intrinsic viscosity. If the degree of polymerization is higher than that, spinnability decreases,
Moreover, the obtained fiber physical properties have a tensile strength of approximately 50/d.
pi! The Young's modulus is approximately 14-0 g/d, which is at an extremely low level compared to polyester and polyamide fibers used as industrial or industrial fibers.

In other words, this means that even if the degree of polymerization of the AN-based polymer constituting the fiber is increased in order to produce acrylic fibers with high fiber properties, the resulting fibers will have low drawability (but not necessarily the same). This means that it is not possible to produce acrylic fibers with high tri-N physical properties proportional to the degree of polymerization of the ΔN polymer.

(Problems to be Solved by the Invention) The purpose of the present invention is to use an AN polymer with a polymerization degree as high as possible, and to produce acrylic fibers that have high fiber properties, especially mechanical strength, that reflect this polymerization degree. It is in providing the law. Another object of the present invention is to provide a method for producing high-strength acrylic fibers that can be stretched to a high degree even though the AN polymer constituting the fibers has a high degree of polymerization.

<Means for Solving the Problems> The object of the present invention is to provide a solution with an intrinsic viscosity of at least 2
．． Dry/wet-spun an AN-based polymer solution with a concentration of at least 1. This can be achieved by carrying out dry heat stretching while developing a stretching tension of C1/d, with a total stretching ratio of at least 10 times or more.

-5 In the present invention, in the dry/wet spinning method, an AN-based polymer solution is used as a spinning dope, and the spinning dope is discharged from a spinneret hole;
This is a method in which the discharged yarn is once run in air or an inert atmosphere such as nitrogen, argon, helium, etc., and then introduced into a coagulation bath to form a coagulated yarn. ΔN with a high degree of polymerization of 2.0 or more
This dry/wet spinning is a prerequisite for producing acrylic fibers with high fiber properties using polymers.

The m-string that is the object of the method of the present invention has high fiber properties, particularly high mechanical strength, for example, tensile strength of 10 g/d or more,
Preferably 12 g/d or more, the elastic modulus is 180 q/d
or more, preferably 200Q/d or more, and the knot strength is 2.0
It has excellent physical properties of at least g/d, preferably at least 2.5 q/d.

Further, as the AN-based polymer, various known polymers can be used, but at least 90 mol% of AN, preferably 95 mol% or more, and 5 mol% or less of a vinyl compound copolymerizable with the AN.

Preferably, an AN homopolymer or a ΔN copolymer containing 0 to 5 mol% is preferable. When the copolymerization component of AN exceeds 10 mol%, heat resistance and compactness decrease, resulting in poor 41
I can't get Ji Wei.

The above-mentioned vinyl compound may be any compound having copolymerizability with various known ΔNs, and is not particularly limited. Preferred copolymerizable components include acrylic acid, itaconic acid, methyl acrylate, methyl methacrylate, and acetic acid. Examples include vinyl, sodium allylsulfonate, and sodium p-styrenesulfonate.

Such AN-based polymers can be used in solvents such as dimethyl sulfoxide (DMSO), dimethyl formamide (
DMF), dimethylacetamide (DMΔC), ethylene carbonate, organic solvents such as butyl rough 1~, water-soluble inorganic salts such as zinc chloride, calcium chloride, lidium bromide, sulfur thiocyanide, etc.) dissolved in a thick aqueous solution. Then, the obtained polymer solution is used as a spinning dope, that is, a spinning dope.

-7 In the present invention, the degree of polymerization of the AN-based polymer is at least 2.0 or more, preferably 3.0 to 5, expressed as an intrinsic viscosity.
．． A range of 0 is used.

In other words, if the intrinsic viscosity is less than 2.0, there is a limit to the improvement in the strength and physical properties of the obtained fibers, for example, it will be difficult to produce fibers with a tensile strength of 10 g/d or more. If the degree of polymerization becomes high, the viscosity of the spinning dope becomes too large, making it impossible to perform stable spinning in the dry/wet spinning method employed in the present invention, which is not preferred.

Here, the intrinsic viscosity in the present invention is a value measured by the following method.

Approximately 75 mg of dry polymer (sample) is placed in a 25 ml flask and dimethyl 7''-lumamide containing 0.1N sodium thiocyanate is added to completely dissolve. The specific viscosity peak of the obtained solution was measured at 20° C. using an Ostwald viscometer, and the intrinsic viscosity was determined according to the following formula.

0.198 The feature of the present invention is dry and wet spinning of 1 q of elongated strips by dry heating, preferably in air at a humidity of 160 to 220° C., at least 1.0 g/d.

Preferably 1.5-2. The point is that the stretching is carried out under conditions that produce a stretching tension in the range of oq and 'd. The steps leading up to the drawing step are not particularly limited, and for example, after the above-mentioned dry/wet spinning, a step of washing with water, drying and densification, and first drawing under moist heat, or washing with water, first drawing in hot water, and drying and densification. For example, the process of

That is, in the present invention, the steps from dry/warm spinning to dry heat stretching are not critical, but the dry heat stretching conditions are the same.

Then, stretching is carried out under the development of a stretching tension that satisfies the above conditions, and the total stretching ratio is 10 times or more, preferably 1.
Only by setting the conditions to increase the density by 5 to 20 times, it is possible to obtain fibers having a high degree of fineness, which is the object of the present invention.

If the stretching tension under dry heat is lower than 1 q/d, the orientation of the polymer chains in the II m-axis direction during this stretching will be insufficient, resulting in the advanced fiber properties of the present invention.

In particular, it becomes difficult to produce 1q of fibers with mechanical strength.

In addition, although such dry heat stretching conditions are closely related to the adoption of dry/wet spinning, it is difficult to perform high-level stretching using dry heat stretching alone. It is desirable that the fiber threads to be subjected to dry heat drawing be primarily drawn in advance by approximately 2 to 10 times, preferably 4 to 8 times.

The temperature of the dry heat stretching is 160 to 220°C.

Preferably, the range is from 180 to 200°C. If it is lower than 160°C, a sufficient stretching ratio cannot be obtained, so it is not preferable, and if it exceeds 220°C, it is not preferable. This is undesirable because it involves a decrease in stretchability due to the lack of heat resistance of the fibers.

Specific dry heat stretching means include, but are not particularly limited to, hot plates, hot drums, hot tubes, etc.; Using a cylinder, the yarn is passed through the heating cylinder which is maintained at a predetermined humidity. It is best to stretch while

Note that the single yarn denier of the fiber thus obtained is not limited to 1S, but is generally 3D or less.

(Effects of the Invention) According to the present invention, high degree of fiber properties can be achieved by applying a specific spinning method of dry/wet spinning to a ΔN-based polymer with a high degree of polymerization.
In particular, acrylic fibers, which are important for mechanical strength, can be manufactured industrially, and the resulting fibers can be used not only for industrial material applications where conventional acrylic fibers could not be used, but also for use as reinforcing materials. 1 Reinforcement) Various composite materials designated as A (
As a reinforcing agent for composites 1-) or carbon lAl1
It can be used as a pre-curly for maintenance, greatly expanding the uses of acrylic fibers, and is extremely useful.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1. Comparative Examples 1 to 3 A solution of ΔN alone was prepared using DMSO as a solvent to prepare an AN homopolymer solution having an intrinsic viscosity of 3.2. The polymer concentration of the jq polymer solution was adjusted to 15.5% by weight, and wet-dry spinning was performed.

The distance I11 between the spinneret surface and the liquid level of the coagulation bath, that is, the length of the space, was set to 5 mm, and a 60% DMS○ aqueous solution at 15°C was used as the coagulation bath, and the coagulated fiber thread was taken from the coagulation bath. The speed was set at 10 m/min and stretched 5 times in hot water. The obtained drawn fiber yarn is washed with water,
After applying an oil solution for 1 time, it was dried and densified at 120°C.

The obtained dried fiber threads were subjected to second drawing in pressurized steam and dry hot air.

Stretching and sampling were performed at 90% of the maximum secondary stretching ratio, and the stretching tension and fiber braiding strength were measured. Table 1 shows the results.

= 12 - Table 1 (Note) In the above table, the heating humidity using dry heated air is 190°C.

In the case of pressurized steam stretching, the total stretching ratio is higher than the stretching ratio in dry hot air, but the stretching elongation J is considerably lower, and as a result, the tensile strength is lower.

On the other hand, when stretched with dry hot air, the strength of -13
High-performance acrylic fibers were obtained, with a polygonal strength of 12.1 g/d, an elastic modulus of 205 c+/d, and a knot strength of 3.10/d.

Examples 2-4. Comparative Example 4 An AN-based polymer having an intrinsic viscosity of 3.9 was prepared in the same manner as in Example 1, and dry/wet spinning was performed.

The length of the space is 10 mm, and the temperature is 50°C at 20°C as the same bath.
% DMSO aqueous solution was used. After solidification, it was washed with water and stretched 5 times in hot water. After applying an oil agent to the obtained fiber yarn, it was dried and densified at 110°C.

The obtained dry fiber yarn was subjected to secondary stretching using a dry heat duplex by changing the heat F@drinking supplied into the tube, and sampling was performed at 90% of the maximum stretching ratio to measure the physical properties. The measurement results are shown in Table 2.

= 14 - Table 2 =15- □A〇-

Claims (2)

[Claims] (1) Dry/wet-spun an acrylonitrile polymer solution with an intrinsic viscosity of at least 2.0, dry heat stretching the resulting yarn under a stretching tension of at least 1.0 g/d, and total stretching ratio. 1. A method for producing acrylic fibers having high fiber physical properties, characterized in that the fiber properties are increased by at least 10 times or more. (2) The method for producing acrylic fibers having high fiber physical properties, wherein the dry heat drawing temperature is within the range of 160 to 220°C, as set forth in claim 1.