JPS58163716A - Preparation of acetate fiber - Google Patents

Abstract

PURPOSE:To obtain acetate fibers with prevented occurrence of broken yarns in the fiber making step, by dissolving cellulose diacetate in a mixture of methylene chloride with methanol, and spinning the resultant spinning solution by the dry spinning method. CONSTITUTION:Cellulose diacetate is dissolved in a mixture of methylene chloride with 8-15wt% methanol to give 21-24wt% cellulose diacetate concentration, and the resultant spinning solution is then heated at 70-80 deg.C and extruded through spinning nozzles at a speed ratio satisfying the formula (VT/VE)<=0.85 (VE is the speed of the spinning solution extruded through the spinning nozzle; VT is the yarn taking off speed) by the dry spinning method.

Description

[Detailed description of the invention] The present invention relates to a method for producing acetate fibers.

More specifically, the present invention relates to a method for producing acetate fibers using a dry spinning method from a spinning stock solution in which cellulose diacetate is dissolved in a mixture of methylene chloride and methanol.

Diacetate fibers are generally produced by dry spinning from spinning dope using aceto/or a mixture of acetone and water as the solvent, whereas triacetate fibers are produced using methylene chloride or a mixture of methylene chloride and methanol as the solvent. It is manufactured using a dry spinning method from a spinning stock solution. Factories that manufacture these two types of acetate fibers often have separate spinning buildings and solvent recovery equipment in order to prevent the vapors of each solvent from mixing and recover them separately. It is possible to manufacture these two types of acetate fibers in the same spinning building and solvent recovery equipment, but in the case of acetate fibers, if the recovered solvent is not precisely distilled, the spinning process using the spinning dope containing the recovered solvent is not possible. Trouble will occur frequently. When diacetate fibers are produced by a dry spinning method from a spinning stock solution using methylene chloride or a mixture of methylene chloride and methanol as a solvent, diacetate fibers and triacetate textile fibers are produced using a common building and a solvent recovery device. However, this method has the disadvantage that yarn breakage occurs frequently during the spinning process.

The present inventor has reduced yarn breakage in the spinning process in a method for producing acetate fiber by dry spinning from a spinning dope in which cellulose diacetate is dissolved in a mixture of methylene chloride and methanol, and thereby As a result of intensive studies aimed at making it possible to manufacture triacetate fibers in the same building, we determined the mixing ratio of methylene chloride and methanol used as a solvent (hereinafter referred to as the solvent mixing ratio) and the spinning dope. The concentration of cellulose diacetate in the solution (hereinafter referred to as the concentration of the stock solution).

) have a large influence on the incidence of yarn breakage in the spinning process, and when these two factors are within a certain limited optimum range, the occurrence of yarn breakage in the spinning process will be reduced. We have discovered this and arrived at the present invention.

That is, the gist of the present invention is to provide a method for producing acetate fibers by a dry spinning method from a spinning stock solution in which cellulose diacetate is dissolved in an organic solvent. The proportion of methanol in the mixture is 8% by weight or more and 75% by weight or less.'

■ The concentration of cellulose diacetate in the spinning stock solution is 21
4. Must be at least 24% by weight and not more than 24% by weight. .

It is characterized by:

The solvent mixing ratio has a great influence on the incidence of yarn breakage during the spinning process and on the physical properties of the spun yarn. When the proportion of methanol is 8% by weight or less, as the proportion of methanol decreases, the occurrence of yarn breakage in the spinning process increases; when the proportion of methanol is 15% or more, the proportion of spun yarn increases as the proportion of methanol increases. strength and elongation are reduced.

From this, it is appropriate that the proportion of methanol be 8% by weight or more and 15% by weight or less.

The concentration of the stock solution also did not significantly affect the incidence of yarn breakage during the spinning process and the physical properties of the spun yarn. Regarding the concentration of the stock solution, see 1. The higher the concentration, the higher the productivity of the stock solution preparation process and the cost required for solvent recovery can be reduced, so from the viewpoint of manufacturing costs, it is desirable that the stock solution concentration is as high as possible. However, if the stock solution concentration is 24% by weight or more, As the yarn breakage rate suddenly increases, the elongation of the spun yarn decreases. If the concentration of the stock solution is less than 21%, the production cost will increase and the proportion of single fibers with abnormal fiber cross-sectional shapes in the spun yarn will increase. From this, it is appropriate that the concentration of the stock solution is in the range of 21% by weight or more and 24% by weight or less.

Further, in carrying out the present invention, it is preferable to heat the spinning stock solution to a temperature of 70° C. or higher and 80° C. or lower and then discharge it from the spinning nozzle. The higher the temperature of the spinning dope, the higher the elongation of the spun yarn, so it is desirable to keep the temperature high within a range that does not increase the incidence of yarn breakage during the spinning process.

In the case of the method of the present invention, if the spinning dope is heated to 80°C or higher, the incidence of yarn breakage will be extremely high, and if it is below 70°C, the elongation of the spun yarn will be low. It is desirable that the temperature be within the range of 80°C or below.

Furthermore, in the present invention, the ratio VT/VE of the speed VE at which the spinning dope is discharged from the spinning nozzle and the yarn pick-up speed vT is
If VT/VE is 0.85 or more, the incidence of yarn breakage during the spinning process becomes extremely high, so it is desirable that the VT/VE ratio be 0.85 or less. This speed ratio V T / V E is determined by the fineness (D del = -) and number of filaments (F) of the first number to be spun, the concentration (C weight %) of the spinning dope, and the density (P,
! ii'/cm'), nozzle hole radius (rcm)
Since the value is proportional to r2 as shown in equation (1), the nozzle hole radius r may be determined so that VT/VE is 0.85 or less.

(However, A is a constant.) The present invention will be explained in more detail below according to examples.

Example 1 A solution in which a predetermined amount of cellulose diacetate was dissolved in a mixture of methylene chloride and methanol mixed in the proportions shown in Table 1 was filtered as usual to obtain a spinning stock solution,
After heating this spinning dope to 75°C, vT/vE was 0.
85 or less and 0.80 or more, dried in the usual manner and pulled off at a speed of 800 m/min to obtain an acetate fiber of 100 denier 27 filaments. Shown in the table. In Table 1, the stock solution concentration is the weight concentration (%) of the proportion of cellulose diacetate contained in the spinning stock solution, and the methanol ratio is the proportion of methanol contained in the mixture of methylene chloride and methanol. It is a value expressed in weight concentration (%), and the yarn breakage incidence is a value indicating the number of yarn breakages occurring per 100 spindles per day in the spinning process. It is a value of elongation, and the occurrence rate of abnormal cross section is a value indicating the proportion (%) of filaments whose fiber cross section has an abnormal shape. In order to determine whether or not the fiber cross section is abnormal, the fiber cross section was observed under a microscope, and a filament with 3 or less concave portions and 3 convex portions each was determined to be a filament with an abnormal repair surface.

Table 1 Example-2 A solution in which cellulose diacetate is dissolved at a concentration of 22 weight percent in a mixture of methylene chloride and methanol with a methanol ratio of 12 weight percent is filtered as usual to obtain a spinning stock solution. After heating this spinning dope to the temperature shown in Table 2, the VT/VE ratio was 0.
It was discharged from a spinning nozzle with a force of 85 or less and 0.80 or more, and dried in the usual manner for 800 m.
The acetate fibers were taken at a speed of 7 minutes to obtain 100 denier 27 filament acetate fibers, and the results are shown in Table 2. Example 3 Cellulose diacetate was added to a mixture of chloride, methylene and methanol with a methanol ratio of 12% by weight. The solution dissolved so that the concentration is 22% by weight is filtered as usual to obtain a spinning stock solution, and this spinning stock solution is discharged from a spinning nozzle with a nozzle hole diameter of 37μ to 41μ and dried as usual for 800 m Acetate fibers of 27 filaments of 100 denier were obtained and the results are shown in Table 3.

Table 3 Procedural Amendment (Voluntary) I--Japan Patent Office Commissioner Kazuo Wakasugi 1, Indication of the case, Patent Application No. 41734, filed in 1982, 2, Name of the invention: Process for producing acetate fiber 3, Relationship with the person making the amendment Patent applicant 2-3-19 Kyobashi, Chuo-ku, Tokyo (621) President and Director of Mitsubishi Acetate Co., Ltd.
Kato Second Part Voluntary Amendment 6, Specification to be amended, Specification, and Claims 1) "75 weight" on page 4, line 8 of the specification is corrected to "15 weight."

3) Line 9 of page 6 of the specification "Spinning speed process" was corrected to "spinning process" that's all.

2. Claims [(1) - Cellulose diacetate is added to a spinning dope in an organic solvent that is a mixture of methylene chloride and methanol, and the proportion of methanol in this mixture is 8% by weight or more and 15% by weight or less. The concentration of cellulose diacetate in
1. A method for producing acetate fiber, which comprises spinning the dissolved acetate fiber by a dry spinning method so that the content is 1% by weight or more and 1% by weight or less.

(2) The method according to claim 1, characterized in that the spinning stock solution is heated to a temperature of 70° C. or higher and 80° C. or lower and then discharged from a spinning nozzle.

(3) The speed at which the spinning dope is discharged from the spinning nozzle ■, and the yarn take-up speed V? The method according to claims 1 and 2, characterized in that dry spinning is carried out under conditions such that the ratio VT/V is 0685 or less. ”

Claims (2)

[Claims] (1) Cellulose diacetate is a mixture of methylene chloride and methanol, and the concentration of cellulose diacetate in the spinning stock solution is added to an organic solvent in which the proportion of methanol in this mixture is 8% by weight or more and 15% by weight or less. A method for producing acetate fiber, which comprises spinning a dissolved acetate fiber at a concentration of 21% by weight or more and 24% by weight using a dry spinning method. (2) The method according to claim 1, characterized in that the spinning stock solution is heated to a temperature of 70° C. or higher and 80° C. or lower and then discharged from a spinning nozzle. (3) The spinning stock solution is discharged from a spinning nozzle. Claims 1 and 2 are characterized in that dry spinning is carried out under conditions such that the ratio VT/VE of the spinning speed (E) and the light weight withdrawal speed (VT) is 0.85 or less. the method of.