JPH10168643A - Production of synthetic fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing synthetic fibers that can suppress the occurrence of abnormal polymers and reduce filament breakage during the spinning. SOLUTION: In the process that a molten polymer is extruded through a spinning head 1 equipped with a metering pump 3 and a spinning pack 4, the polymer temperature in the metering pump is made lower than that in the spinning pack. In a preferred embodiment, the difference in temperature between the molten polymer in the metering pump 3 and that in the spinning pack 4 is set to >=5 deg.C, more preferably, the temperature of the molten polymer (T) in the metering pump 3 is adjusted to the melting point of the polymer +25 deg.C>=T>= the melting point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic fiber by a melt spinning method, and more particularly, to a method for producing a synthetic fiber which reduces the quality abnormality of a polymer which causes yarn breakage during melt spinning. About.

[0002]

2. Description of the Related Art The production of synthetic fibers such as polyester and polyamide is performed by using a melt spinning machine having a spinning head equipped with a measuring pump and a spinning pack. After the melt spinning, stretching is performed if necessary, and the film is continuously wound around a bobbin. In the melt-spinning winding process, the spun yarn may break during the winding, or a part of the single yarn in the spun yarn may break, and the frequency of these yarn breaks may be reduced. It is very important to reduce the number in order to improve productivity and quality.

Hitherto, various causes of the above-described spun yarn breakage have been studied, and a method of reducing foreign matter in a polymer, a method of regulating a shape of a spinneret, or controlling an airflow below the spinneret according to the cause has been studied. A method for preventing spun yarn breakage has been proposed. However, the present situation is that the thread break has not yet been completely eliminated.

The inventors of the present invention have conducted various studies on the cause of spun yarn breakage, and as a result, have noticed that the main cause of yarn breakage is thermal degradation of the polymer. That is, in the conventional melt spinning machine, a measuring pump and a spinning pack are provided on one spinning head, and both are heated to the same temperature based on the melt spinning temperature. Was higher than the spin pack. For this reason, the molten polymer tends to undergo considerable thermal degradation from the high-temperature metering pump to the spinning pack. Therefore, when the thermally degraded polymer portion is discharged from the spinning pack, the yarn breaks and appears.

[0005] In particular, in the case of fine denier yarn, the spinning time from the metering pump to the spinneret becomes long, the amount of heat brought in from the molten polymer is small, and the atmospheric temperature under the spinneret becomes low. Since the temperature of the head is set to be high, the thermal degradation of the molten polymer is more likely to occur, and the spun yarn is more likely to occur.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a synthetic fiber in which abnormal polymers during melt spinning are suppressed to reduce spun yarn breakage.

[0007]

A method for producing a synthetic fiber according to the present invention is a method for spinning a molten polymer from a spinning head provided with a metering pump and a spinning pack. It is characterized in that the temperature is lower than the molten polymer temperature. Preferably, the temperature difference between the molten polymer temperature in the metering pump and the molten polymer temperature in the spin pack is 5
° C or more, and more preferably, the temperature of the molten polymer in the metering pump is higher than or equal to the melting point of
C. or less.

As described above, by setting the temperature of the molten polymer in the metering pump relatively lower than that in the spinning pack, thermal deterioration of the molten polymer during the flow from the metering pump to the spinning pack is suppressed, and the quality is improved. And the breakage of spun yarn can be reduced. In particular, by setting the temperature difference between the molten polymer temperature in the metering pump and the molten polymer temperature in the spin pack to 5 ° C. or more, and / or the molten polymer temperature in the metering pump to the melting point of the polymer or more and the melting point + 25 ° C. or less. This effect can be further improved.

[0009]

FIG. 1 is a schematic view showing a spinning head of a melt spinning machine used in the method for producing a synthetic fiber of the present invention. The spinning head 1 has an inlet 2 for molten polymer in the upper center.
The inflow port 2 is connected to a melting section of a melt spinning machine (not shown) or a polymerization apparatus.

The spinning head 1 is divided into a chamber 1a filled with a heating medium Q and a chamber 1b provided with an electric heater H, and a spinning pack 4 containing a filter medium 4a, a spinneret 4b and the like is housed in each chamber 1a. A metering pump 3 such as a gear pump is disposed in the chamber 1b. In addition, the chamber 1a is heated to a higher temperature than the chamber 1b. A heat insulating material 7 is arranged on the outer periphery of the spinning head 1.

Here, the heating chamber 1 in which the metering pump 3 is housed.
As a, as shown in FIG. 2, the electric heater H may not be provided, and the temperature may be simply kept by the heat retaining material 7. In the case of FIG. 2, the chamber 1 containing the spinning pack 4 is also provided.
b is heated to a higher temperature than the chamber 1a in which the metering pump 3 is stored. The heating means may be any of a heating medium, an electric heater or other means.

The molten polymer inlet 2 is connected to a metering pump 3 via a pipe 5, and the metering pump 3 is connected to a spinning pack 4 via a pipe 6. By being connected in this manner, the molten polymer supplied to the inflow port 2 of the spinning head 1 is supplied to the spinning pack 4 while being metered by a metering pump 3 in a fixed amount, and further supplied to the spinning pack 4.
The yarn Y is spun into yarn.

According to the method for producing synthetic fibers of the present invention, the temperature of the molten polymer in the metering pump 3 is set lower than the temperature of the molten polymer in the spinning pack 4 using the above-described melt spinning machine. ing. Thus, the metering pump 3
By lowering the temperature of the molten polymer inside, the thermal degradation of the molten polymer until it reaches the spin pack is reduced, thus reducing the unevenness of the spun yarn, improving the yarn quality, and reducing the spun yarn breakage. It can be significantly reduced.

In order to ensure such an effect, the temperature difference between the molten polymer temperature of the metering pump and the molten polymer temperature of the spinning pack is preferably 5 ° C. or more, more preferably 10 ° C. or more. It is better to However, if the temperature difference is too large, the flow in the pipe becomes uneven due to the difference in viscosity of the polymer, and there is a problem that the measuring property is further deteriorated. Therefore, the upper limit of the temperature difference is set to 40 ° C. preferable.

Further, in the present invention, the temperature of the molten polymer in the metering pump is preferably not less than the melting point of the raw material (polymer) and not more than + 25 ° C., and more preferably not less than the melting point of the raw material (polymer) and not more than + 20 ° C. It is good to be below ° C. The temperature set in this manner is considerably lower than the temperature employed in the conventional melt spinning method, and is naturally sufficiently lower than the temperature of the spin pack. Therefore, the molten polymer hardly undergoes thermal deterioration during the period from the metering pump to the spinning pack. As a result, quality deterioration such as yarn unevenness of the spun yarn is reduced, and spun yarn breakage is further reduced. be able to.

In the present invention, the spinning speed at the time of melt spinning is not particularly limited, but is preferably from 1000 m / min to 6000 m / min. Spinning speed is 1
If it is less than 000 m / min, the discharge amount will be small, causing a problem that the polymer temperature will decrease.
When the speed is higher than m / min, the problem that the spinnability decreases is caused.

The raw material polymer applied to the present invention is not particularly limited as long as it can be melt-spun. For example, a polyester-based polymer containing ethylene terephthalate, butylene terephthalate, or the like as a main component, or a polyamide-based polymer containing nylon 6, nylon 66, or the like as a main component can be exemplified. These raw material polymers are particularly effective when applied to yarn having a fineness of 75d or less.

Further, the melt spinning method applied to the present invention comprises:
Chip melting spinning in which a chip-shaped raw material polymer is melted and spun, or continuous polymerization spinning directly connected to the polymerization step may be used.

[0019]

EXAMPLE A polyethylene terephthalate chip having a melting point of 260.degree. C. was melted at 290.degree. C., and a spinning head shown in FIG. The temperature of the pack, the temperature of the metering pump, and the discharge rate were variously changed as shown in Table 1 (Examples 1 to 7, Comparative Examples 1 to 4).

For each of Examples 1 to 7 and Comparative Examples 1 to 4, broken spun yarn and broken single yarn (measured with a FRAY COUNTER manufactured by Toray Engineering)
Was evaluated, the results shown in Table 1 were obtained. As is clear from Table 1, in Examples 1 to 7, both yarn breakage and single yarn breakage are small, and it is understood that the quality is stable. However, in Comparative Examples No. 1 to 4, yarn breakage and single yarn breakage were extremely large, and the quality was not satisfactory.

[0021]

[Table 1]

[0022]

As described above, according to the present invention, the melt polymer is moved from the metering pump to the spin pack in order to melt-spin the melt polymer in the metering pump at a temperature lower than that in the spin pack. It is possible to suppress the thermal deterioration of the molten polymer during the heating, to improve the quality and to reduce the breakage of the spun yarn.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a spinning head of a melt spinning machine used in a method for producing a synthetic fiber of the present invention.

FIG. 2 is a schematic view showing a spinning head portion according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spinning head 1a, 1b chamber 3 Metering pump 4 Spinning pack 7 Heat insulating material Q Heat medium H Electric heater

Claims (5)

[Claims] 1. A method for spinning a molten polymer from a spinning head provided with a metering pump and a spinning pack, wherein the temperature of the molten polymer in the metering pump is lower than the temperature of the molten polymer in the spinning pack. 2. The synthetic fiber production method according to claim 1, wherein the temperature difference between the temperature of the molten polymer in the metering pump and the temperature of the molten polymer in the spin pack is 5 ° C. or more. 3. The synthetic fiber production method according to claim 1, wherein the temperature of the molten polymer in the metering pump is not lower than the melting point of the polymer and not higher than + 25 ° C. 4. The spinning speed of the molten polymer is 1000.
The method for producing a synthetic fiber according to claim 1, 2 or 3, wherein the speed is not less than m / min and not more than 6000 m / min. 5. The spinning head is divided into a chamber for accommodating the metering pump and a chamber for accommodating the spinning pack, and the chamber for accommodating the spinning pack has a higher temperature than the chamber for accommodating the metering pump. The method for producing a synthetic fiber according to claim 1, wherein the synthetic fiber is heated.