JP2003138423A - Method for producing polyester fiber for industrial use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester fiber for a industrial use, enabling to draw the fiber at a high drawing ratio, that is the polylactate fiber having high strength sufficiently applicable to the industrial use is produced with good operability. SOLUTION: This method for producing the polyester fiber for the industrial material comprises spinning out the polylactate polymer having a melting point (Tm) of >=130 deg.C through nozzles, then cooling, furnishing with a finish, aspirating, further drawing the spun fiber directly without winding it in an intermediate stage, and finally winding the drawn fiber at a winding speed of >=1500 m/min, wherein the first stage of the drawing of the fiber is conducted by blowing steam which is heated with a heating means to have a temperature higher than the Tm on the fiber so that the fiber is thermally drawn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester for industrial use, which contains polylactic acid as a main component and is capable of producing polyester fiber suitable for industrial materials and daily life materials requiring high strength with good stretchability. The present invention relates to a fiber manufacturing method.

[0002]

2. Description of the Related Art Conventionally, many processed products such as fibers, films, non-woven fabrics and molded products using thermoplastic resins have been mass-produced for convenience. However, on the other hand, concerns over exhaustion of petroleum resources and disposal of waste after use have become an environmental problem.

Along with this, some resins, such as PET bottles, containing relatively few impurities are collected and recycled into fibers and the like.
These recycled fibers are valued as environmentally friendly products. However, from the perspective of petroleum products as a whole, it is only a part, and there are still a large amount of waste, and the environmental problems have not yet been solved.

Under these circumstances, a processed product using a polylactic acid resin, which is an aliphatic polyester made from corn, has been attracting attention in recent years. Since polylactic acid has biodegradability and antibacterial properties and is excellent in hydrolyzability, it can be decomposed by landfill or composite treatment.

However, in general, a fiber mainly made of polylactic acid resin is compared with polyethylene terephthalate (PET) which is generally used for industrial purposes,
Since the strength is weak, the hydrolysis resistance is poor, and the melting point is low, the application range is limited.

Therefore, various methods have been proposed for obtaining high-strength polylactic acid fibers as polylactic acid fibers that can be used for industrial purposes. One of the means is to obtain a high-strength fiber by performing drawing at a high draw ratio during drawing.
However, when the draw ratio of the polylactic acid-based fiber is increased, devitrification, which is presumed to be caused by voids, is likely to occur, and in a state where such devitrification occurs, operability deteriorates, and However, it was difficult to obtain high strength even if the draw ratio was increased.

Japanese Patent Laid-Open No. 2000-136435 describes a method for producing a high-strength polylactic acid-based fiber by adjusting the moisture content of the yarn and performing hot drawing. As described in this publication, by optimizing the heating temperature of the roller, it is possible to obtain a high-strength polylactic acid-based fiber by increasing the draw ratio while suppressing the occurrence of devitrification. But,
It was necessary to raise the heating temperature of the roller for high-stretching.

However, as the roller temperature is increased, the yarn swaying on the roller increases in proportion to this, especially the yarn swaying on the roller before stretching becomes severe, and fluff is often generated and cut. There was a problem of becoming. In particular, when a multi-end yarn is drawn, contact and overlap between yarns are likely to occur, and this problem is remarkable.

As described above, there is a limit to the high-magnification stretching only by adjusting the roller temperature. Further, a method of additionally using heated air or heated steam having a melting point temperature or lower has been proposed, but although these have some effects, stable operability has not been obtained.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above problems, makes it possible to stretch at a high ratio, and provides a polylactic acid fiber having high strength which can be sufficiently used for industrial purposes with good operability. It is a technical subject to provide a method for producing a polyester fiber for industrial use that can be produced.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted studies to solve the above problems, and as a result of the heat drawing while blowing steam having a temperature equal to or higher than the melting point during the first drawing, the In addition to preventing the occurrence of transparency, it is possible to draw at a high draw ratio, and it is possible to align the yarns before drawing and to heat the take-up roller for preheating without heating or at low temperature, which reduces yarn shaking. Therefore, they have found that the multi-end yarn can be stably drawn, and have arrived at the present invention.

That is, according to the present invention, a polyester made of a polylactic acid-based polymer having a melting point of 130 ° C. or higher is spun from a melt spinneret, then cooled, and an oil agent is applied to the polyester, which is continuously taken up without being wound up. Stretched 1500m /
In the manufacturing method of winding in more than a minute,
The gist is a method for producing a polyester fiber for industrial use, which is characterized in that hot drawing is performed while blowing steam having a temperature equal to or higher than a melting point (Tm).

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The polylactic acid polymer used in the production method of the present invention has a melting point of 130 ° C. or higher, more preferably 150 ° C. or higher. If the melting point is less than 130 ° C, the use is limited, which is not preferable. Specifically, the main component is a copolymer of optical isomers of L-lactic acid and D-lactic acid, and of these, the optical purity of L-lactic acid is preferably 85.0 to 99.5%.

The ratio of L-form to D-form is a factor affecting heat resistance and biodegradability. Generally, when the ratio of the L-form is low, the crystallinity is lowered, the melting point is lowered, and at the same time, the biodegradation rate is increased. However, if the purity of the L-form is lower than this range, the melting point is low, the fiber becomes inferior in heat resistance, the spinnability is deteriorated, and hot drawing becomes difficult. When the purity of the L-form is higher than this range, the crystallization temperature is high and the decomposition rate is slow, resulting in a fiber having poor biodegradability.

Since the fiber obtained by the production method of the present invention is intended to be used for industrial purposes, the melt viscosity of the polylactic acid-based polymer used is the melt flow rate value (hereinafter referred to as MFR).
Referred to as: according to ASTM-D1238, temperature 210 ℃,
Value measured under a load of 2160 g) is 1 g / 10 minutes to 40
g / 10 minutes is preferred. If the MFR is less than 1 g / 10 minutes, the melt viscosity will be too large and the spinnability will be reduced.
If it exceeds 10 minutes, it tends to be difficult to obtain high-strength fibers.

In the present invention, the above-mentioned polylactic acid-based polymer may be added to the above-mentioned polylactic acid polymer, if necessary, for example, a heat stabilizer, a crystal nucleating agent, a matting agent, a pigment, a light resistance agent, a weather resistance agent, an antioxidant, an antibacterial agent. Agents, fragrances, plasticizers, dyes, surfactants, surface modifiers,
Various additives such as various inorganic and organic electrolytes, fine powders, flame retardants and the like can be added within a range that does not impair the effects of the present invention.

In the production method of the present invention, the polylactic acid-based polymer as described above is melt-spun, cooled, given an oil agent, and then continuously stretched without being once wound.
It is a spin draw method of winding at a rate of 00 m / min or more. In the present invention, the melting point (T
The point is to perform hot drawing by spraying steam having a temperature of m) or higher.

By thus blowing hot steam and performing hot stretching, the stretching point is fixed, and it becomes possible to stretch at a high magnification. Especially the temperature of steam is 2.0 which is the melting point.
It is preferably set to be 2.5 times. This makes it possible to smoothly perform stretching at a high magnification. If the temperature is lower than the melting point, high-stretching cannot be smoothly carried out, and devitrification occurs or fluff occurs in the obtained fiber. On the other hand, when it exceeds 2.5 times, the polymer is modified and the strength is lowered.

As a method of spraying steam, it is preferable to spray steam symmetrically along the running direction of the yarn from a plurality of spray ports. The number of spray ports and the spray angle of steam are not particularly limited, but as shown in FIG. 1, at an angle of 45 degrees toward the yarn running direction, 2
It is preferable that the steam is sprayed symmetrically from each orifice 11 (spraying port). In this way, the point X at which steam is blown from both orifices 11 becomes the stretching point, and the stretching point can be fixed, so that stretching at a high magnification becomes possible. At this time, it is preferable that the undrawn yarn Y runs in the cylinder 22 in the vicinity of the blowing portion. However, since this cylinder 22 is for preventing the scattering of steam, the length is 3 to 10 cm.
Something is enough.

The spraying steam preferably has a blowing pressure of 0.3 to 0.7 MPa. The blowing pressure of the steam depends on the flow rate and the flow rate of the steam, but the pressure is preferably within the above range. The flow rate is preferably 10 to 50 kg / hour. Blowing pressure is less than 0.3 MPa,
When the flow rate is less than 10 kg / hour, devitrification is likely to occur, and it is difficult to perform high-strength stretching. On the other hand, the blowing pressure exceeds 0.7 MPa and the flow rate is 5
When it exceeds 0 kg / hour, the running of the yarn becomes unstable, fixing of the drawing point tends to be difficult, and it is also disadvantageous in terms of cost.

In this first-stage stretching, it is preferable to carry out 50% or more of the total draw ratio, and more preferably 70% or more. If it is less than 50%, crystallization will proceed, resulting in a decrease in the total draw ratio and making it difficult to obtain high-strength fibers. Further, although only the first stage stretching may be performed, the second stage stretching is preferable because high strength is easily obtained.

By such hot steam drawing, the drawing can be sufficiently carried out without heating the take-up roller or the aligning roller before drawing, the yarn sway on the roller is reduced, and the cost can be reduced.

In the production method of the present invention, the winding speed is 1500 m / min or more, preferably 2000-3.
000 m / min. If it is less than 1500 m / min, it is disadvantageous in terms of cost, and if it exceeds 3000 m / min, it becomes difficult to stretch at a high ratio, it becomes difficult to obtain high strength, and the spinnability is deteriorated, which is not preferable.

The fiber obtained by the production method of the present invention has a strength of preferably 4.5 cN / dtex or more, and more preferably 5.0 cN / dtex or more, though it depends on the draw ratio. The cross-sectional shape is not particularly limited, and may be a round cross section or an irregular cross section.

Although the fineness can be set arbitrarily, the total fineness is 300 to 2000 because it is used for industrial purposes.
dtex, and the fineness of the single yarn is preferably about 2 to 30 dtex.

Next, the present invention will be described with reference to the drawings. FIG. 2 is a schematic process drawing showing one embodiment of the manufacturing method of the present invention. First, a spinneret is attached to a conventional melt spinning apparatus, spinning is performed at a temperature of 200 to 240 ° C., an annular spraying apparatus having a length of 20 to 50 cm is used, and a temperature of 10 to 40 ° C. and a speed of 0.
After cooling with air of 3 to 2.0 m / sec, an oil agent is applied and taken out.

At this time, the inner wall temperature was 200 to 4 immediately after spinning.
It is preferable to pass through a heating cylinder having a length of 10 to 30 cm heated to 00 ° C. and then cool. This can reduce the orientation of the undrawn yarn and enhance the drawability.

Then, as shown in FIG. 2, the undrawn yarn Y is applied to the unheated first roller 1 a plurality of times to be taken up, and subsequently applied to the unheated second roller 2 a plurality of times to obtain a magnification of 1.00.
Alignment of 5 to 1.05 is performed. Subsequently, the steam is passed through the steam treatment machine 6 and hung on the third roller 3 heated to a temperature of 100 to 150 ° C. a plurality of times, and the first stage at a draw ratio of 4.0 to 6.0 in the steam treatment machine 6. Is stretched. Subsequently, the fourth roller 4 heated to 100 to 150 ° C. is applied a plurality of times to perform the second stage stretching at a stretching ratio of 1.1 to 1.5, and then a relaxation treatment of 0.90 to 0.99 times. While performing, wind up on the winder 5 at a speed of 1500 m / min or more.

[0029]

EXAMPLES Next, the present invention will be specifically described with reference to examples. In addition, the measurement of each physical property value and various evaluations in the examples were performed as follows. (A) Melting point (° C) Using a differential scanning calorimeter DSC-2 type manufactured by Perkin Elma Co., Ltd., a sample of about 5 mg, in nitrogen, heating rate 10 ° C / min, 20
The maximum melting exothermic peak temperature when the temperature was kept at 0 ° C. for 5 minutes, the temperature was decreased to 20 ° C. at a temperature decreasing rate of 10 ° C./minute, and the temperature was again increased to 200 ° C. at a temperature increasing rate of 10 ° C./minute was taken as the melting point (Tm). did. (B) Glass transition temperature (° C.) The initial exothermic peak temperature obtained when measuring the melting point was taken as the glass transition temperature (Tg). (C) MFR (g / 10 minutes) Measured according to ASTM D1238 at 210 ° C. under a load of 2160 g. (D) Strength and Elongation According to JIS L-1013, a Shimadzu Corporation Autograph DSS-500 was used to measure a sample length of 25 cm and a pulling speed of 30 cm / min. (E) Evaluation of devitrification The degree of whitening of the obtained fiber was visually judged and evaluated according to the following three grades. No whitening ・ ・ ・ ○ Whitening degree is small △ △ Whitening degree is large ・ ・ ・ × (f) Evaluation of yarn sway on the aligning roller (second roller 2) Yarn sway on the roller The size of was evaluated by the following three grades visually. Small ・ ・ ・ ○ Medium ・ ・ ・ △ Large ・ ・ ・ ×

Example 1 A conventional melt-spinning apparatus was equipped with a pore size of 0.5 μm and a number of holes of 192.
Equipped with a conventional spinneret in which two pieces are arranged in a group of 2 holes, the optical purity is 99.5%, the MFR is 8 g / 10 minutes, the glass transition temperature (Tg) is 63 ° C., and the melting point (Tm) is 175. ℃
Poly L-lactic acid of was spun at a temperature of 225 ° C. After passing through a heating cylinder with an inner wall temperature of 300 ° C and a length of 20 cm installed immediately below the mouthpiece, it was cooled with a cooling wind at a temperature of 15 ° C and a speed of 0.6 m / sec using an annular blowing device with a blowing length of 40 cm. Then, an oiling agent was applied with an oiling roller to divide the yarn into two parts. Subsequently, stretching was performed as shown in the schematic process drawing shown in FIG. First, the first roller of 319 m / min, which is not heated, is wound four times to pull out the two yarns, and then each yarn is wound five times, on the second roller of unheated, which is 328 m / min, five times to 1.03 times. By using the steam treatment machine (length 4 cm) shown in FIG. 1 at a temperature of 380 ° C.
While spraying steam with a pressure of 0.4 MPa and a flow rate of 15 kg / hour, the speed was 1708 m / min and the temperature was 130 ° C.
The roller was stretched 5 times to draw the first stage at a draw ratio of 5.2. Subsequently, the second roller was stretched 5 times on a fourth roller at a speed of 2050 m / min and a temperature of 130 ° C. for a second stage at a draw ratio of 1.2, and then wound on a winder at a speed of 2000 m / min with 2 cups and 555 dtex / 96. A polyester fiber having a filament and a round cross section was obtained.

Example 2 Optical purity was 95.0%, MFR was 10 g / min, Tg56
℃, Tm 152 ℃ poly L-lactic acid, temperature 210 ℃
The same procedure as in Example 1 was performed, except that the inner wall temperature was passed through a heating cylinder having a temperature of 280 ° C., the steam having a temperature of 340 ° C. was sprayed, and the temperatures of the third and fourth rollers were lowered by 15 ° C.

Examples 3 and 4 The procedure of Example 1 was repeated except that the steam temperature was changed to the values shown in Table 1.

Comparative Example 1 The steam treatment machine was removed and the temperature of the second roller was adjusted to 110
The same procedure as in Example 1 was carried out except that the temperature was raised to 0 ° C. and the roller was stretched.

Comparative Example 2 The procedure of Comparative Example 1 was repeated, except that the temperature of the second roller was 90 ° C.

Comparative Example 3 The procedure of Example 1 was repeated except that the steam temperature was changed to the value shown in Table 1.

Table 1 shows the physical property values and evaluation results of the fibers obtained in Examples 1 to 4 and Comparative Examples 1 to 3.

[0037]

[Table 1]

As is clear from Table 1, the fibers obtained in Examples 1 to 4 had sufficient strength and cutting elongation, and were devitrified and suitable for production. In addition, it was possible to produce with good operability without causing yarn sway. On the other hand, in Comparative Example 1, the steam treatment machine was not provided and the second roller was used as the heating roller to perform stretching between the rollers, so that the yarn sway was large and stable operation was difficult. Comparative Example 2 is also an example in which the steam treatment machine was not provided, but the temperature was made lower than that of Comparative Example 1 in order to reduce the yarn wobbling on the second roller, but devitrification occurred in the obtained fiber. , Fluff is generated,
The strength and cutting elongation were also inferior. In Comparative Example 3, since the steam temperature in the steam treatment machine was too low, smooth stretching could not be performed, and the obtained fiber had devitrification and fluffing.

[0039]

According to the manufacturing method of the present invention, it is possible to carry out a smooth drawing at a high magnification and to prevent the yarn from shaking on the roller. It becomes possible to manufacture the polylactic acid fiber having the above-mentioned properties with good operability.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a cross section of a steam processing machine used in a manufacturing method of the present invention.

FIG. 2 is a schematic process drawing showing one embodiment of the production method of the present invention.

[Explanation of symbols]

1st roller 2 Second roller 3rd roller 4th roller 5 winders 6 steam processing machine 11 Orifice 22 cylinder Y undrawn yarn X stretch point

Claims (2)

[Claims] 1. A polyester composed of a polylactic acid-based polymer having a melting point of 130 ° C. or higher is spun from a melt spinneret, then cooled, an oil agent is applied thereto and taken out, and continuous drawing is carried out without winding once. A method for producing a polyester fiber for industrial use, which comprises drawing the first stage by hot drawing while blowing steam having a temperature of a melting point (Tm) or higher in a manufacturing method of winding at 1500 m / min or more. 2. The method for producing polyester fiber for industrial use according to claim 1, wherein steam is sprayed symmetrically along the running direction of the yarn from a plurality of spray ports.