KR850000810B1 - Method for producing the spinning solution of acrylonitrile type polymer containing uniformly dispersed titanium oxide - Google Patents

Abstract

Titanium oxide particles are dispersed in water so that their wt. ratio is below 70 %. The spinning soln. is produced by dissolving acrylonitrile copolymer is organic solvent, e.g. DMF. After the titanium oxide dispersion is fed to the spinning soln. so that the concn. of titanium oxide dispersion is below 8%, they are mixed so that the apparent shearing speed S is more than 900 per second. The speed S is shown by the equation: S = (2P:RN)/γ where R is radius of the mixing blade, N is the number of revolutions of the mixing blade, and γ is the clearance between the dispersion inlet and the mixing blade.

Description

Process for preparing acrylonitrile polymer spinning stock containing homogeneously dispersed titanium oxide

The present invention relates to a method for producing an acrylonitrile (hereinafter referred to as AN) polymer spinning stock solution containing titanium oxide uniformly dispersed. More specifically, the spinning stock solution and titanium oxide obtained by dissolving AN polymer in its solvent The present invention relates to a method for producing an AN-based polymer spinning stock solution containing finely and uniformly dispersed titanium oxide by mixing a uniform aqueous dispersion formed by dispersing in water under specific conditions.

In manufacturing artificial fibers, films, etc. from viscous polymer solutions (spinning solutions), in order to modify the properties of the final product, before release, a colorant such as a flatting agent such as titanium dioxide, a pigment or a dye Several methods have been practiced in which various solid additives, such as polish and ultraviolet absorbers, are mixed with the radiation source solution to achieve the object.

As one of such methods, there is a method of subdividing this additive into a grinder such as a colloid mill, and then mixing the additive in a spinning stock solution by using a stirrer, a printing machine, or the like. However, it is extremely difficult to uniformly disperse and mix the solid additives in the highly viscous solution used for spinning the synthetic fibers, and when the mixing time or the time until the release after mixing becomes long, the finely ground particles aggregate and become agglomerates. Therefore, problems such as shortening of the filter life, breakage at the time of discharge and increase in the amount of loss of the additive are inherent.

As another method, there is a method (master batch method) using a dispersion in which the solid additive as described above is suspended in a relatively small amount of viscous solution of the same kind as the spinning stock solution.

This method is considerably improved in the method of directly dispersing and mixing the solid additives in the spinning stock solution, but it requires the same complicated process as solvent addition, degassing, filtration, etc., in spite of making a small amount of viscous solution. In addition, since it is a viscous solution, there is a problem in that it is extremely difficult to redisperse the once-aggregated additive.

In another method, the solid additive is dissolved or suspended in a solvent miscible with the spinning stock solution to be coagulated, and then mixed with the spinning stock solution to form a uniform dispersion of colloidal particles with the above additive, followed by wet spinning to make the additive particles uniform. A method of manufacturing artificial fibers and the like that are dispersed in a clear manner is apparent.

However, in the method of using a solvent which can be dissolved in the spinning stock solution as an additive medium, it is inevitably necessary to dilute the polymer solvent, resulting in gelation of the spinning stock solution, which causes problems such as incapacity. Since the dispersion solvent is incorporated in the recovery system, there are many industrial and economic disadvantages, such as making recovery of this solvent difficult.

Herein, the present inventors have diligently studied to alleviate such defects, and thus, by introducing a water dispersion obtained by dispersing a predetermined amount of titanium oxide in water at a predetermined ratio into the spinning stock solution and mixing under specific conditions, it causes gelation or aggregation. Titanium oxide can be uniformly dispersed and mixed in the AN-based polymer spinning stock solution without any problem, thereby eliminating problems such as clogging of the nozzle hole and breaking of the thread during discharge, and finally adding a small amount of titanium oxide effectively. The present invention has been found to find an industrially advantageous method for producing a systemic polymer spinning stock solution capable of providing a glossless acrylic fiber.

In other words, an object of the present invention is to finely and uniformly disperse and mix titanium oxide in an AN polymer spinning stock solution, thereby eliminating the problem of clogging of the nozzle hole at the time of discharge, and finally adding a small amount of titanium oxide. It is to provide an industrially advantageous method for producing an AN-based polymer spinning stock solution that can provide an acrylic fiber that has been effectively polished (neglected), and a further object of the present invention is more apparent by the following detailed description of the invention Will be.

This object of the present invention is achieved by the method described in the claims to be described later.

The AN polymer may be polyacrylonitrile or at least 50% by weight, preferably 60% by weight, or more than AN and vinyl esters such as vinyl compounds copolymerizable with AN, such as vinyl acetate and vinyl propionate; Vinyl halides and vinylidene halides such as vinyl chloride, vinyl bromide, vinylidene chloride and vinylidene bromide; Copolymers such as acrylic acid, methacrylic acid, itaconic acid and their lower alkyl esters, vinylsulfonic acid, allylsulfonic acid, metalylsulfonic acid, styrenesulfonic acid and salts thereof, but are not limited to these.

In addition, as a solvent for dissolving the AN polymer to form a spinning stock solution, for example, organic solvents such as dimethylformamide, dimethyl acetamide, dimethyl acetamide, dimethyl sulfoxide, concentrated aqueous solution of rhodan salts such as rhodan sodium, rhodan potassium, rhodan ammonium, Inorganic solvents such as rich zinc chloride rich aqueous solution, concentrated aqueous solution of strong acid such as nitric acid, sulfuric acid, etc. may be mentioned, but the use of inorganic solvents makes it possible to uniformly oxidize evenly without causing gelation or agglomeration at the time of mixing titanium oxide aqueous dispersion. Titanium may be dispersed and mixed, which is preferable.

As the titanium oxide used in the present invention, the anatase type and rutile type can be enumerated, but the anatase type is preferable from the viewpoint of dispersibility and quality, although it is not particularly limited.

As the titanium oxide concentration of the titanium oxide aqueous dispersion introduced into the spinning stock solution, it is necessary to set it in the range of 70% by weight or less, preferably 50% by weight or less. If it is out of this range, it is difficult to produce a uniform dispersion. The aqueous dispersion cannot be uniformly mixed in the spinning stock solution.

The mixing ratio of the aqueous dispersion introduced into the spinning stock solution should be set within the range of 8 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less, based on 100 parts by weight of the spinning stock solution. If it is out of the range, even if it mixes under the conditions mentioned later, it is unpreferable since it causes problems, such as gelatinization of a spinning stock solution and clogging of a nozzle.

As a method of introducing and mixing a predetermined amount of the above-described titanium oxide water dispersion in the spinning stock solution, the apparent shear rate specified by the following general formula is 9. 0-10 ² / sec. It is necessary to mix under the above conditions.

Where S is the apparent shear rate (1 / sec.), Π is the circumference rate R is the radius of the stirring blade (m), N is the rotational speed of the stirring blade (1 / sec), and r is the tip of the water dispersion inlet and the tip of the stirring blade. Clearance m is displayed.

In addition, any stirrer may be employed as long as it satisfies such mixing conditions. However, in addition to the general ones such as turbine wings, turban blades, spiral blades, and crotch wings, the present inventors have disclosed in the specification of Japanese Patent Application No. 52-31583. [Piline mixer] manufactured by Shimaaki Co., Ltd., [Pipeline homomixer made by Special Vaporization Corporation], [Flomix] made by Nettco (USA), Chemineer [In-Line Agitater] etc. made by a company (USA) can be mentioned.

In addition, it is preferable to introduce a titanium oxide aqueous dispersion because the introduction of the titanium oxide aqueous dispersion in a direction parallel to the rotational axis of the stirring blade can effectively prevent abrasion of the stirring blade and can effectively disperse the di-dispersant in the spinning stock solution.

By employing the technical means of the present invention as described above, titanium oxide is finely and uniformly dispersed in the AN-based polymer spinning stock solution without the complicated process as in the conventional method for preventing gelation of the spinning stock solution. AN which can be mixed and thus does not cause problems such as clogging of nozzles and breaking of threads during spinning, and can finally provide an acrylic fiber that is effectively polished by addition of a small amount of titanium oxide. It is a characteristic advantage of the present invention that the polymer based spinning solution can be prepared.

Next, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited at all by the description of these Examples.

In addition, the part and percentage in an Example are shown on a basis of weight unless there is particular understanding.

Example 1

3 parts of 50% aqueous dispersion of titanium dioxide (Anatase type, particle size: 0.3μ), 44% of AN polymer consisting of 90% AN and 10% methyl acrylate, aqueous monosodium solution (polymer concentration 11%) 100 In addition, using the stirring apparatus provided with the turbine blade of four blades, it introduce | transduced continuously in parallel with the stirring blade rotation axis, and mixed and stirred on the conditions of the following 1st table | surface.

The measurement result of the obtained spinning stock solution is listed in the 1st table | surface.

[Table 1]

(Note) 1) Dispersibility: Sample is observed under a microscope (150 times)

2) Filterability (KW): By using a 400 mesh nylon filament filter cloth, constant pressure filtration (pressure 2 atmospheres) was used to calculate the KW value by the following equation.

Where P ₁ is the filtration weight of 0-20 minutes after the start of filtration and P ₂ is the filtration weight of 20-60 minutes. (The details of the measurement method are described in [Spinning and Film Forming of Chemical Fibers (II), p. 123, [Japan]]

As apparent from the results in Table 1, in Experiment Nos. 2 and 3, a spinning stock solution having good bagability was obtained without any problems such as breakage of the yarn or clogging of the nozzle hole with respect to prolonged spinning. In the case of Experiment Nos. 1 and 4, the spinning stock solution that could withstand long-term radiation stably due to the clogging of the nozzles caused by the mixed gelate was not obtained.

Next, even when the introduction direction of the titanium dioxide water dispersion was installed at right angles to the rotational axis of the stirring blade under the same conditions as in Experiment No. 2, a good dispersion state of the spinning stock solution was obtained. Since the abrasion occurred and the dispersing effect decreased, it was necessary to replace or repair the stirring blade, but in Experiment No. 2, the wear was hardly recognized even for continuous operation for more than one month.

Claims (1)

Acrylonitrile-based polymer spinning

To uniformly disperse titanium oxide in the stock solution, disperse the titanium oxide particles in water at a rate of 70% by weight or less to form a uniform water dispersion, and then disperse 8 parts by weight or less with respect to 100 parts by weight of the spinning stock solution. The apparent shear rate specified by the following general formula was introduced into the spinning stock solution in the ratio of 9. 0 × 10 ² / sec. A process for producing an acrylonitrile-based polymer spinning stock solution containing a uniform dispersion of titanium oxide, characterized by mixing under the above conditions.

Where S is the apparent shear rate (1 / sec.), Π is the circumference rate, R is the radius of the stirring blades (m), N is the rotational speed of the stirring blades (1 / sec.), And r is the tip of the aqueous dispersion inlet and agitation. Clearance (m) with the tip of the wing is indicated.