JPH11200143A - Spinning of polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spinning process for poly(trimethylene terephthalate) that can give the yarns of good quality as the spinneret wiping cycle can be prolonged. SOLUTION: The orifice surface temperature is set to 230-280 deg.C and a silicone mold releasing agent that contains methylphenyl-silicone and dimehylsilicone and has the viscosity of 2,000-8,000 cpoise is coated on the spinneret face. The surface area of the polymer passing through one orifice on the spinneret is controlled in the range from 5,000-30,000 mm<3> /min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melt-spinning polytrimethylene terephthalate for preventing stains on a spinneret surface.

[0002]

2. Description of the Related Art In general, a melt spinning method of polyester comprises
This is performed by extruding the melt from a spinneret.
In such spinning, ring-shaped dirt (hereinafter, referred to as “scale”) is deposited around the nozzle discharge hole as time elapses from the start of spinning. This scale is considered to be deposited due to thermal degradation and oxidative degradation because a part of the discharged polymer remains on the die surface.

[0003] The scale increases with time, and as a result, the spun yarn bends and spiking occurs. If the bend becomes severe, a phenomenon occurs in which the yarn breaks until the yarn comes into contact with the surface of the die. Even if the yarn is not broken, if the bend or spike becomes large, yarn spots become large or fuzz is generated, and it becomes difficult to obtain a yarn of satisfactory quality. In order to suppress this phenomenon, a silicone-based release agent is usually applied, but the release agent attached to the die surface deteriorates over time with heat or oxidation, thereby degrading the releasability. The ability to suppress this phenomenon is reduced.

In ordinary spinning of a polyester polymer typified by polyethylene terephthalate, an operation called wiping is performed to clean the die surface in such a state and renew the release agent. However, this operation requires a great deal of manpower, and it is desired to extend the wiping cycle in order to significantly reduce production efficiency such as interruption of production and generation of waste. In particular, polytrimethylene terephthalate uses trimethylene glycol as the glycol component, and its structure makes it more susceptible to thermal and oxidative degradation than polyethylene terephthalate and polybutylene terephthalate. Because of the easiness and the like, there is a serious disadvantage that the scale is particularly heavily deposited and the wiping cycle is shortened. Therefore, sufficient spinning stability could not be obtained simply by applying a known spinning stabilization method.

For the purpose of extending the wiping cycle, a method has been known in which the space under the base is sealed with an inert gas such as nitrogen to suppress the oxidative deterioration of the adhered polymer (Japanese Patent Laid-Open No. 52-1).
No. 5613). However, in this method, spun yarn breakage due to the inert gas seal itself frequently occurs, and it has been difficult to industrially use the spun yarn. There is also known a method in which the bottom of the base is sealed with steam to suppress the oxidative deterioration of the attached polymer, and furthermore, the attached polymer is reduced to a low molecular weight substance by depolymerization with steam so as to be easily removed (Japanese Patent Laid-Open No. Sho 52).
No. 15613). However, in the case of polyester, the water vapor causes transformation of the metal additive contained in the catalyst and the like, and this transformation deposits around the discharge holes, resulting in deterioration of spinnability. It is also known that an air atmosphere is maintained just below the base surface in a specific dew point range (Japanese Patent Application Laid-Open No. 57-56515). However, even with this method, it is impossible to fundamentally reduce the amount of the polymer adhering to the spinneret, and the effect of extending the wiping cycle cannot be said to be sufficient for a polymer that easily adheres to the spinneret and deteriorates drastically.

[0006] As a method for melt spinning polytrimethylene terephthalate, several methods are known (JP-A-52-5320, JP-A-52-8124, JP-A-8-284015, etc.). ). However, there is no description of a method for extending the wiping cycle in these methods, and when spinning is performed by these methods, scale deposits on the surface of the die are severe, and wiping must be performed quite frequently. The production efficiency is remarkably reduced due to interruption of production and generation of debris during that time.

[0007]

DISCLOSURE OF THE INVENTION The present invention is directed to a polytrimethylene terephthalate which can improve the above-mentioned drawbacks of the conventional polyester spinning method, can extend the wiping cycle, and can obtain a yarn having good yarn quality. The present invention relates to a spinning method.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned drawbacks. As a result, the polytrimethylene glycol can be obtained by using specific spinning conditions and using a specific release agent. The present invention has provided a spinning method which can extend the wiping cycle when spinning the yarn and can obtain a yarn with good yarn quality with less unevenness in the yarn diameter.

That is, a first aspect of the present invention is that the spinning surface temperature is 230 to 280 ° C., which contains methylphenyl silicon and dimethyl silicon, and has a viscosity of 2000 to 800.
This is a method for melt spinning polytrimethylene terephthalate, which comprises applying a silicone-based release agent of 0 cpoise to the spinneret surface. Further, the second aspect of the present invention is that the surface area of the polymer passing through a single hole of the spinning nozzle is 5,000 to 30.
The melt spinning method of the polytrimethylene terephthalate according to the first invention, wherein the melt spinning rate is 000 mm ² / min.

The spinning method of the present invention can be applied to the production of both filaments and staples. In particular, it can be effectively applied to the production of fine denier filaments having a denier of 5 denier or less after drawing. The polytrimethylene terephthalate in the present invention refers to a polyester polymer containing terephthalic acid as an acid component and containing at least 80 mol% of trimethylene glycol as a glycol component. In the present invention, the trimethylene glycol is selected from among 1,3-propanediol, 1,2-propanediol, 1,1-propanediol, 2,2-propanediol, and a mixture thereof. From the viewpoint of 1,3-propanediol is particularly preferred.

In the polytrimethylene terephthalate used in the present invention, if necessary, isophthalic acid, succinic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, etc. may be used as long as the effects of the present invention are not impaired. A glycol component such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or polyoxyalkylene glycol may be copolymerized as the glycol component. If necessary, various additives such as a matting agent, a heat stabilizer, a flame retardant, an antistatic agent, and an antifoaming agent may be copolymerized or mixed. The polymer used in the present invention can be polymerized by a known polyester polymerization method.

In the spinning method of the present invention, the intrinsic viscosity [η] of polytrimethylene terephthalate is 0.4 to 1.4.
It is preferred that When the intrinsic viscosity [η] exceeds 1.4, the melt viscosity becomes high and not only becomes difficult to extrude with a usual spinning machine, but also tends to adhere to the spinning surface. If the intrinsic viscosity is less than 0.4, mechanical properties such as fiber strength are reduced. Preferred intrinsic viscosity [η] is
It is in the range of 0.5 to 0.9.

In the melt spinning of the present invention, the surface temperature of the spinning nozzle needs to be 230 to 280 ° C. If the surface temperature of the spinneret is lower than 230 ° C., the melt viscosity becomes higher and extrusion becomes difficult. If the temperature exceeds 280 ° C., the melt viscosity decreases, so that the polymer easily adheres to the surface of the spinneret, Deterioration becomes severe and scale deposition becomes severe. The spinning surface temperature is preferably from 235C to 265C.

The present invention contains methylphenylsilicon and dimethylsilicon, and has a solution viscosity of 2000 to 800.
It is also necessary to apply a silicone-based release agent that is 0 cpoise to the spinneret surface. The release agent contains methylphenyl silicon and dimethyl silicon,
The heat resistance and releasability of the release agent are improved, and the wiping cycle is extended. The proportion of these components is 4% for the phenyl component.
It is preferable that the amount is 0 to 80 parts by weight and the amount of dimethyl silicon is 60 to 20 parts by weight. The viscosity of the release agent is very important in suppressing the scale deposition. Viscosity 200
If the viscosity is less than 0 cpoise, the viscosity of the release agent is too low.
The release agent around the discharge hole adheres to the polymer in a short time and disappears, and the release effect cannot be maintained for a long time. On the other hand, if the viscosity exceeds 8000 cpoise, the viscosity is too high, so that the releasability is inferior, and the deposition of scale is rather accelerated. The viscosity of the release agent is 3000
~ 7000 cpoise is preferred. The release agent may contain other substances such as SiO _{2 in} addition to the above components.

The release agent is applied after wiping the spinning nozzle, but may be sprayed at other times. In the present invention it is important that the surface area of the polymer passing through a single hole of the spinning nozzle is 5000~30000mm ² / min. The scale attached to the spinneret surface is generated because a part of the discharged polymer remains around the pores. Therefore, it is important to reduce the amount of polymer that contacts the perimeter of the pore.
For this purpose, it is necessary to make the surface area of the polymer passing through a single hole constant. If the surface area of the polymer passing through a single hole exceeds 30,000 mm ² / min, a large amount of polymer remains around the hole, so that the scale is increased and the wiping cycle is shortened. On the other hand, 500
If it is less than 0 mm ² / min, productivity is extremely deteriorated due to a small amount of discharged polymer, and since the diameter of the spinning nozzle must be increased, it is necessary to increase the draft to obtain a yarn having good mechanical properties. Yes, and as a result, thread breakage occurs frequently. The preferred range is 7000 to 25000 mm
² / min, and a more preferred range is 10,000 to 200.
00 mm ² / min.

The shape of the spout is not particularly limited, and is applied to a round cross section, a triangular cross section, a hollow cross section and the like. The fiber bundle discharged from the spinneret and quenched immediately below the spinneret is taken out, wound up as an undrawn yarn, and drawn by a known method. At the time of collection, the fiber bundles are bundled, and a known lubrication or pre-entanglement is applied.

The winding speed of the undrawn yarn is 1000 to 5
The speed is preferably 000 m / min, and particularly preferably from 1500 to 3500 m / min from the viewpoint of strength development. If the spinning speed exceeds 5000 m / min, the yarn diameter unevenness will increase. In the case of stretching, the crystallization of molecules progresses too much during the spinning process, and it is difficult to perform sufficient orientation stretching by stretching. Further, when the spinning speed is less than 1000 m / min, the degree of orientation of the undrawn yarn does not become so high, so that it is difficult to sufficiently orient the molecules in subsequent drawing, and it is difficult to develop sufficient strength. .

The fiber obtained according to the present invention may or may not be drawn after winding. In the case of drawing, the undrawn yarn may be once wound and then drawn, or may be continuously drawn between two or more godet rolls without being once wound. The stretching ratio is usually 1.5-3.
Five times is preferred. Although the draw ratio varies depending on the winding speed and the yarn type of the undrawn yarn, it is preferable that the drawing be performed at 70 to 99% of the breaking draw ratio.

The stretching temperature is preferably 30 ° C. to 80 ° C., preferably 35 ° C. to 70 ° C., and more preferably 45 ° C. to 60 ° C. When the stretching temperature is lower than 35 ° C., yarn breakage occurs frequently at the time of stretching, and continuous stretching cannot be performed. If the stretching temperature exceeds 80 ° C., the slipperiness with a stretching roll or the like is deteriorated, and single yarn breakage occurs frequently, making stable stretching difficult. The drawn yarn needs to be subjected to a heat treatment. Heat treatment after stretching is 90 ° C to 200 ° C,
Preferably, it is necessary to carry out at 100 ° C to 190 ° C. If the heat treatment temperature is lower than 90 ° C., the crystallinity of the fiber cannot be sufficiently increased, and it is difficult to obtain a fiber having good mechanical properties. If the heat treatment temperature is 200 ° C. or higher, the fibers are likely to break, making it difficult to perform heat treatment continuously.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples and the like, but the present invention is not limited to the examples and the like. In addition, the main measurement value in an Example was measured by the following method. (1) Intrinsic viscosity [η] Intrinsic viscosity [η] is a value obtained based on the following definition formula.

[0021]

(Equation 1) Ηr in the definition formula is a value obtained by dividing the viscosity at 35 ° C. of a diluted solution of polytrimethylene terephthalate dissolved in o-chlorophenol having a purity of 98% or more by the viscosity of the solvent itself measured at the same temperature, It is defined as relative viscosity. C is the solute weight value in grams in 100 ml of the solution.

(2) Surface area of polymer passing through a single hole The surface area of a polymer passing through a single hole was determined according to the following equation. Surface area = (V × M) / (ρ × S) (mm ² / min) V: Discharge rate of single hole (g / min) ρ: Density of polymer (g / mm ³ ) S: Cross-sectional area of hole ( mm ² ) M: Perimeter of pore (mm) (3) Viscosity of release agent Measured at room temperature using a B-type viscometer. (4) Wiping cycle The spinning was performed five times under the spinning conditions of each example, and the average value of the time until the occurrence of thread breakage was defined as the wiping cycle.

[0023]

Example 1 Polymerization of 1,3-propanediol and dimethyl terephthalate by a conventional method was conducted to obtain an intrinsic viscosity [η] of 0.1.
As a result, polytrimethylene terephthalate polymer No. 7 was obtained.
This polytrimethylene terephthalate polymer was used at a spinning surface temperature of 253 ° C. using a spinning hole in which 36 holes having a diameter of 0.35 mm were arranged concentrically, and the discharge rate was 23.1.
Extruded at g / min and spun. At this time, the surface area of the polymer passing through the single hole was 16,900 mm ² / min.
Before starting the winding, a silicone release agent containing 50 parts by weight of methylphenylsilicon and 30 parts by weight of dimethylsilicone and having a solution viscosity of 5000 cpoise was applied to the surface of the spinneret. The extruded yarn was wound at 1600 m / min to obtain an undrawn yarn. The wiping cycle at this time is 24
Time was good. The obtained undrawn yarn is subjected to hot roll 55 ° C., hot plate 140 ° C. and draw ratio 2.6.
The film was drawn at a draw speed of 800 m / min. To give a drawn yarn of 50.5 denier / 36 filaments. The obtained fiber had a strength of 4.3 g / d and an elongation of 31%. The results are shown in Table 1.

[0024]

Examples 2 to 4 and Comparative Examples 1 to 5 Spinning was carried out in the same manner as in Example 1 except that the type of the release agent and the spinning surface temperature were changed. As the release agent, a silicone release agent containing 50 parts by weight of methylphenyl silicon and 30 parts by weight of dimethyl silicon and having a solution viscosity of 5000 cpoise as in Example 1 was used. A good wiping cycle was obtained under spinning conditions within the range of the present invention. On the other hand, there was a problem with insufficient wiping cycle or yarn quality under spinning conditions outside the scope of the present invention. The results are shown in Table 1.

[0025]

[Table 1]

[0026]

Examples 5 and 6, Comparative Examples 6 to 8 Spinning was carried out in the same manner as in Example 1 except that the spinning diameter and the discharge amount were changed.
The results are shown in Table 2. A good wiping cycle was obtained under spinning conditions within the range of the present invention. On the other hand, there is a problem with insufficient wiping cycle or yarn quality under spinning conditions outside the scope of the present invention.

[0027]

[Table 2]

[0028]

According to the spinning method of the present invention, the drawbacks of the conventional polytrimethylene terephthalate spinning method can be improved, the wiping cycle can be extended, and a yarn having good yarn quality can be obtained.

Claims (2)

[Claims] 1. A silicon-based mold release agent having a surface temperature of 230 to 280 ° C., containing methylphenyl silicon and dimethyl silicon, and having a viscosity of 2000 to 8000 cpoise, is applied to the surface of the spinneret. A method for melt-spinning polytrimethylene terephthalate. 2. The method according to claim 1, wherein the surface area of the polymer passing through a single hole of the spinneret is 5,000 to 30,000 mm ² / min.