JPS62268812A - Production of acrylonitrile fiber - Google Patents

Abstract

PURPOSE:To easily obtain the titled fiber having excellent feeling and gloss, etc., without using a plasticizer such as water, by melt-spinning an acrylonitrile polymer mixture having a specific composition at a specific temperature. CONSTITUTION:For example, a mixture of (A) 80-95pts.(wt.) of an acrylonitrile polymer having a reduced viscosity of 0.2-1.0 and (B) 5-20pts. of an acrylonitrile polymer having a weight-average molecular weight of <=5,000 and produced by the copolymerization of acrylonitrile with methyl acrylate, etc., is pulverized or pelletized, supplied to a hot-melt extruder, etc., and melt-spun at 160-230 deg.C. The spun fiber is drawn and heat-set to obtain the objective fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing acrylonitrile fibers useful for clothing or as precursors for producing carbon fibers by a melt spinning method.

[Conventional technology]

When acrylonitrile polymers are heat-treated, the nitrile groups undergo a cyclization reaction and become infusible, so it has been considered difficult to form fibers by melt spinning.

However, various techniques have been proposed for heating and melting acrylonitrile polymers and spinning them. Omotesho 55-50
No. 1061, Japanese Patent Publication No. 59-47723, Japanese Patent Application Publication No. 111859-130315), a meltable composition prepared by adding a higher fatty acid metal salt to an acrylonitrile polymer (Japanese Patent Publication No. 49-34547), acrylonitrile A melt-molding composition comprising a 2i-form or trimer of acrylonitrile and a polymer (Japanese Patent Application Laid-Open No. 1111-1989)
48 Publication) etc. have been proposed.

[Problem that the invention seeks to solve]

However, in the method of using water as a plasticizer, the water-coordinated acrylonitrile polymer is discharged from a spinning nozzle under heating and pressure to form fibers.
Even if the pressure conditions and humidity control conditions of the pressure zone are strictly regulated, it is difficult to prevent the formation of voids due to volatilization of water in the discharged fibrous acrylonitrile polymer composition 1.

On the other hand, acrylonitrile polymer compositions to which higher fatty acid metal salts are added have good processability, but have drawbacks such as decreased mechanical strength of the resulting fibers and coloration.

Furthermore, the method disclosed in JP-A-50-111148 requires a step of washing and removing acrylonitrile dimer or trimer after spinning, and cannot simplify the steps specific to melt spinning technology.

As described above, the current situation is that no satisfactory method has yet been developed for producing fibers by melt spinning that are comparable to fibers obtained by wet spinning or dry spinning. be.

As a result of intensive study by the present inventors in view of the current state of production of acrylonitrile fibers by the melt spinning method, as described above,
The present inventors have discovered that scales can easily produce acrylonitrile fibers without using a plasticizer such as water by heating and melting an acrylonitrile polymer mixture having a specific composition, and have completed the present invention.

[Means for solving problems]

The present invention uses 80 to 95 parts by weight of an acrylonitrile polymer (A) having a reduced viscosity of 0.2 to 1.0 and a weight average molecular weight of 5 oo.
A method for producing an acrylonitrile fiber, which comprises melt spinning a mixture of 5 to 20 parts by weight of an acrylonitrile polymer (B) at a temperature of 160 to 230°C.

In the present invention, the reduced viscosity is a value measured at 25°C after dissolving 0.5P of polymer in 1001d of dimethylformamide. Moreover, the weight average molecular weight [M w ] is a value determined by the following formula.

[η] =3.55 X 10 [Mw”l'°?1
However, [η]: Intrinsic viscosity (measured in dimethylformamide at 25°C, value extrapolated to a concentration of 0) The acrylonitrile polymer (Al
has a reduced viscosity of 0.2 to 1.0, and a reduced viscosity of 0.2
If it is less than that, not only the melt formability is not good, but also the mechanical strength of the obtained fiber is not sufficient, and the utility value of fiber binding is small. On the other hand, if the reduced viscosity exceeds 1.0, melt spinnability deteriorates and is not preferred.

Further, it is preferable that the acrylonitrile component is contained in the acrylonitrile-based polymer fAl in a proportion of 60 to 95% by weight. If the acrylonitrile component is less than 60% by weight, fibers with excellent fiber performance cannot be produced.

This acrylonitrile-based polymer (Al may be a copolymer of other monomers in addition to acrylonitrile, and monomers that can be copolymerized with acrylonitrile include methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, methyl Acrylate, methacrylic acid such as ethyl acrylate, butyl acrylate, propyl acrylate, esters of acrylic acid, vinyl halides such as vinyl chloride, vinyl bromide, vinylidene chloride, methacrylic acid, acrylic acid, itaconic acid, crotonic acid, Examples include acids such as nyl sulfonic acid and their salts, maleic acid imide, phenylmaleimide, acrylamide, methacrylamide, styrene, α-methylstyrene, vinyl acetate, etc. These monomers may be used alone or in combination of two types. A mixture of the above can be used.

In the production of acrylonitrile polymer (At,
A conventional solution polymerization method, suspension polymerization method, or emulsion polymerization method may be applied. In addition, in order to obtain a reduced viscosity in the range of O22 to 1.0, a molecular weight regulator such as mercaptan is added during polymerization.
By adjusting the amount added, the desired reduced viscosity can be achieved.

On the other hand, when an acrylonitrile-based polymer (Bl has a weight average molecular weight of 500 or less, and a polymer with a molecular weight exceeding 5000) is used, melt spinnability tends to deteriorate.

The acrylonitrile component content in the acrylonitrile-based polymer (Bl) and other monomers that can be copolymerized may be the same as those in the acrylonitrile-based polymer.The polymerization method may also be a normal solution polymerization method or suspension polymerization method. The emulsion polymerization method can be applied, and the weight average molecular weight can be set to 5000 or less by adding a molecular weight regulator such as mercaptan during polymerization and adjusting the amount added.

In addition, the content of the acrylonitrile polymer (Bl component) in the acrylonitrile polymer and in the mixture consisting of (Bl) is preferably 5 to 20 parts by weight based on 100 parts by weight of the mixture.
If the L content is less than 5 parts by weight, melt spinnability will be poor, while if it exceeds 20 parts by weight, melt formability will be poor.

Next, in the present invention, a mixture of two types of polymers and (Bl) is supplied in powder or pellet form to a heated melt extruder, and heated and melted to form fibers.
A temperature range of 30°C is used. At a heating melting temperature of less than 160°C, the polymer will not melt sufficiently to form fibers;
If the temperature exceeds 30°C, the polymer will significantly decompose and become colored, which is not preferable.

The fibrous material discharged from the extruder can then be stretched and heat-set to produce acrylonitrile fibers, which are the object of the present invention.

In the present invention, the spinning speed can be 500 to 5000 m/min, and the spinning speed of acrylonitrile fiber in conventional wet spinning method or dry spinning method is 30 to 200 m/min.
This makes it possible to perform spinning at significantly higher speeds than in minutes.

Further, as the stretching method, hot water stretching, steam stretching, hot plate stretching, hot bottle stretching, etc. can be adopted.

〔Effect of the invention〕

The present invention does not use water or expensive plasticizers, thus eliminating the need for complicated processes, and the resulting fibers also have the texture, gloss, and other excellent mechanical strength characteristic of acrylonitrile fibers. It is something.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that "parts" in the text indicate parts by weight.

The breaking strength and breaking elongation in this example were measured using a Tensilon type tensile tester at a test length of 20+ m and a tensile speed of 20 min/min.
The measurement was carried out in a measurement atmosphere of 20° C. and 65% RH.

Further, the reduced viscosity and weight average molecular weight of the polymer were measured by the methods described above.

Preparation of Example Polymer; Into a reaction vessel equipped with a stirrer and a reflux condenser, add 50 ml of distilled water.
0 parts, (NH,), S, 0.1.2 parts, NH, l5O3
(50% aqueous solution) 20 parts, Fe50.・7 H, O(
0.5t7t') o, 85 parts of acrylonitrile and 15 parts of methyl acrylate were charged, and p
After adjusting the H content to 3 and directly purging the inside of the container with nitrogen, the temperature was raised to 50°C to start polymerization. After 1 hour, polymerization was completed, filtered, washed,
After drying, a powdery polymer (AI') was obtained. The reduced viscosity of the obtained polymer was 0.68.

In addition, the preparation (NHa) * 5tOa it: 0.8
A similar polymerization was carried out to obtain a polymer with a reduced viscosity of 1.2 (
A-■) was obtained.

Polymer (Production of Bl; In a reaction vessel equipped with a stirrer and a reflux condenser, add 30%
0 parts, 3 parts of sodium dioctyl sulfosuccinate, 0.15 parts of potassium persulfate, 42.5 parts of acrylonitrile,
After 7.5 parts of methyl acrylate and 6 parts of lauryl mercaptan were charged and the inside of the container was purged with nitrogen, the temperature of the reaction container was raised to 65° C. while stirring to initiate polymerization. After 15 minutes while controlling the temperature, 85 parts of acrylonitrile, 15 parts of methyl acrylate and 12 parts of lauryl mercaptan were added over 1 hour, and after the addition was completed, stirring was continued for 2 hours to complete the polymerization.

After cooling the obtained emulsion, it was salted out using aluminum chloride, filtered, washed, and dried to obtain a powdery white polymer (B
-I) was obtained. The weight average molecular weight of the polymer was approximately 4,800.

Polymerization was carried out in the same manner as above except that the amount of lauryl mercaptan charged was 3 parts and the amount of additional lauryl mercaptan was 6 parts to obtain a polymer (B-1) having a weight average molecular weight of about 18,000.

Production of acrylonitrile fiber; The acrylonitrile polymer (A
-1) or (A-1t) and the acrylonitrile polymer (B-1) or (B-■) are mixed in the proportions shown in Table 1 and then supplied to a screw type melt extruder, and the die hole @0. An undrawn yarn was obtained by spinning at a spinning temperature of 215° C. and a winding speed of 1200 m for 7 minutes using a die having a diameter of 3 mφ, number of die holes: 72, and length/diameter=2. This undrawn yarn was first placed in boiling water.
A drawn yarn was obtained by drawing at the drawing ratio shown in the table.

The physical properties of the obtained drawn yarn are also listed in Table 1.

Claims (1)

[Claims] Acrylonitrile polymer with a reduced viscosity of 0.2 to 1.0 (
Production of acrylonitrile fiber characterized by melt spinning a mixture consisting of A) 80 to 95 parts by weight and (B) 5 to 20 parts by weight of an acrylonitrile polymer having a weight average molecular weight of 5000 or less at a temperature of 160 to 230°C. Method.