JPH06294010A - Production of polyester monofilament - Google Patents

Abstract

PURPOSE:To enable the industrial production of a polyester monofilament having excellent abrasion resistance and durability. CONSTITUTION:A polyester monofilament blended with a polyolefin-based thermoplastic elastomer is spun by melt-spinning and forcedly cooled immediately after the hot-drawing and/or heat-setting of the monofilament.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester monofilament having excellent abrasion resistance and a method for producing the same.

[0002]

2. Description of the Related Art Monofilaments made of thermoplastic polyester typified by polyethylene terephthalate have been widely used as industrial materials such as papermaking nets, filters and belt cloths because they have excellent mechanical and chemical properties. However, this polyester monofilament has a drawback that it is easily scratched when it comes into contact with hard particles or structures such as metal, ceramics, plastics, etc., and the life as an industrial material is short.

For example, in the case of a papermaking net used for papermaking, when it is used for papermaking in which calcium carbonate is used as a filler such as neutral paper, it has a drawback that the polyester monofilament is rapidly worn. Was. Conventionally, as a method for improving the abrasion resistance of polyester monofilament, JP-A-63-42976 proposes a method of applying a hard coating such as a polysiloxane coating agent and a crosslinked acrylic coating agent to the surface of the monofilament. Has been done. However, this method has a problem in terms of durability because the surface coating is likely to fall off.

Further, Japanese Patent Application Laid-Open No. 2-80688 discloses that
There is a proposal to improve the abrasion resistance by mixing a specific amount of thermoplastic polyurethane with polyethylene terephthalate. However, this method
Spinning is difficult because it decomposes at the melt spinning temperature of polyethylene terephthalate, which poses a problem for industrial commercialization.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a production method which enables industrial production of a polyester monofilament excellent in abrasion resistance and durability.

[0006]

The method for producing a polyester monofilament according to the present invention comprises the steps of mixing polyester with a thermoplastic polyolefin-based elastomer, melt-spinning the monofilament, heat-drawing the monofilament, and immediately after the hot-drawing. It is characterized by forced cooling. Further, when the monofilament is heat set subsequent to hot drawing, it is forcibly cooled immediately after the heat setting.

When a polyester thermoplastic elastomer is mixed with polyester, after the melt-spinning drawing or heat setting, stains containing the polyolefin thermoplastic elastomer as a main component adhere to and accumulate on the rollers which the monofilament first contacts. However, there is a problem that it causes deterioration of the physical properties of the monofilament or winding around the roller and makes continuous operation difficult, but it is forced immediately after hot drawing or immediately after heat setting as in the above manufacturing method. Cooling suppresses the attachment and accumulation of dirt and enables continuous operation.

In the present invention, the polyester forming the monofilament is mainly composed of a polymer composed of a difunctional component such as an aromatic dicarboxylic acid or its dialkyl ester and a glycol component, or a polymer thereof. In particular, polyethylene terephthalate or a material mainly containing polyethylene terephthalate is preferable. The polyester made of polyethylene terephthalate may be a homopolyester or a copolyester.

In the case of copolyester, the copolymerization components include adipic acid, sebacic acid, phthalic acid, naphthalene-
Dicarboxylic acid components such as 2,6-dicarboxylic acid and 5-sodium sulfoisophthalic acid, polyvalent carboxylic acid components such as trimellitic acid and pyromellitic acid, oxycarboxylic acid components such as p-oxyethoxybenzoic acid, and tetramethylene. Glycol, hexamethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, polyoxyalkylene glycol, p-
Examples thereof include diol components such as xylylene glycol, 1,4-cyclohexanedimethanol, and 5-sodium sulforesorcin.

In the present invention, a polyolefin thermoplastic elastomer (hereinafter referred to as TPO) to be mixed with polyester is used.
Means a polymer that exhibits rubber elasticity at normal temperature and plasticity similar to thermoplastic at high temperature.
It is preferable to use a blended product in which a polyolefin such as polypropylene or polyethylene is used as a hard segment and an ethylene / propylene / diene terpolymer is mainly used as a soft segment.

There are various types of TPO, from soft ones to fairly hard ones.
It is preferable to use PO, which gives good abrasion resistance to the polyester monofilament. Specifically, JIS-A hardness measured according to JIS K6301.
(Hereinafter referred to as JIS-A hardness) is preferably 85 or less. Further, various oils for improving kneadability and moldability may be added to this TPO, and more preferably, when the ethylene / propylene / diene terpolymer is used as the soft segment, the soft segment Is preferably partially crosslinked.

The content of TPO in the polyester is preferably in the range of 1 to 40% by weight, more preferably 5 to 30% by weight. If the content is less than 1% by weight, sufficient abrasion resistance cannot be obtained. on the other hand,
If it is more than 40% by weight, not only the strength and elongation of the obtained monofilament tends to decrease and the monofilament wire diameter unevenness tends to increase, but also the stretching and / or
Or, the adhesion and accumulation of dirt on the rollers after the heat setting process is likely to increase.

In the present invention, various antioxidants, various inactive particles such as titanium oxide, and TP are included in the above polyester.
It may contain a small amount of various polymers other than O, various metal compounds as a catalyst usually used in the production of polyester, phosphorus compounds used as an anti-coloring agent, various dyes and pigments, and the like. The cross-sectional shape of the polyester monofilament produced according to the present invention is not particularly limited, and may be any of circle, triangle, square, regular polygon, and the like. However, from the viewpoint of wear resistance, a round cross section is preferred because it is the most resistant to wear. The average diameter of the cross section can be appropriately selected depending on the application, but the range of 0.01 to 3 mm is the best. The filament strength also differs depending on the use, but it is preferable that the net for papermaking be 3.0 g / denier or more.

The method for producing a TPO-added polyester monofilament according to the present invention is carried out as follows. First, before melt spinning, polyester and T
With PO, it is preferable to perform sufficient kneading so that TPO is in a dispersed state as uniform as possible. The kneading can be performed at any stage from the completion of the polycondensation of the polyester to the melt spinning from the spinneret as a monofilament. For example, immediately after the completion of polycondensation, a method of adding and kneading TPO to polyester in a molten state in the polymerization container, adding TPO chips to dried polyester chips and chip blending, and then kneading with an extruder type spinning machine Method, kneading with an extruder type spinning machine while supplying a predetermined amount of polyester chips and TPO chips with a chip constant quantity feeder, or uniaxial or two
Examples include a method of melt-kneading polyester and TPO with a shaft extruder type kneader.

In any case, it is preferable to forcibly knead the polyester and TPO at least once before the melt spinning. As the forced kneading means before the melt spinning, a static blender such as a static mixer may be used in addition to the above-mentioned chip blender or extruder. If forced kneading before melt spinning is not carried out, the dispersibility of TPO will be insufficient, and spiking and bending will occur during melt spinning, stains will occur around the spinneret, and yarn breakage will occur during spinning and drawing. In addition, the monofilament becomes a thread having a large wire diameter unevenness or a thread having low thread properties.

The melt spinning may be carried out by using either a spinning machine with a kneading device such as an extruder or a melt pressure type spinning machine. The spinneret has a diameter D (mm) of the discharge hole and a length of the discharge hole. Length L (mm) is 1.5 ≦ L /
It is preferable to satisfy the relationship of D ≦ 5. If the discharge hole of the spinneret is L / D <1.5, stains may easily adhere to the periphery of the discharge hole during spinning, or the spun yarn may bend and cause spiking. It tends to increase and the spinning becomes unstable. On the other hand, when the discharge hole of the spinneret is L / D> 5, stains are likely to adhere to the periphery of the discharge hole due to an increase in the dispersion effect of the molten polymer discharged from the discharge hole, and spinning becomes unstable.

The melt spinning temperature may be in the same temperature range as that of ordinary polyester melt spinning, which is not lower than the melting temperature of polyester and not higher than the decomposition temperature. At such melt-spinning temperature, TPO does not undergo thermal decomposition, but more preferably 2% to ensure that the decomposition of TPO is avoided.
90 ° C. or lower is preferable. For the same reason, the average contact time between TPO and molten polyester is preferably 15 minutes or less in total, and more preferably 10 minutes or less.

The monofilament melt-spun from the spinneret is introduced into a water tank having a water temperature of 40 ° C. to 80 ° C., cooled, and then subjected to hot drawing and heat setting. The hot stretching may be performed in one stage or may be performed in two stages.
When the drawing is carried out in one stage, it is heated to 100 ° C to 2 by hot air
It may be carried out at 60 ° C. so that the draw ratio is 4.5 to 6.5 times.

When the stretching is carried out in two stages, the first stage stretching is carried out at a temperature of 80 to 97 ° C. and a stretching ratio of 3 to.
It is good to do 5 times. The heating medium for the first-stage drawing may be hot air, but it is advantageous to perform it in hot water because the heating efficiency is good. Subsequent to the first stage stretching, the second stage stretching is carried out by heating with hot air at 100 ° C to 260 ° C so that the total stretching ratio of the first stage and the second stage becomes 4.5 to 6.5 times. .

In the present invention, it is necessary to carry out the forced drawing of the drawn monofilament emerging from the drawing zone after the hot drawing as described above, before it comes into contact with the first rollers. This forced cooling can be performed by various methods such as blowing cold air or cooling with water. Of these, cooling with water (hereinafter referred to as water cooling) is preferable because it has a higher cooling efficiency than cooling with cold air.
Water cooling is performed using water or hot water with a temperature below 70 ° C.
It is preferable to use water having a water temperature of 50 ° C. or lower.

As means for water cooling, any means such as spraying, showering, dipping may be used, but showering and dipping are preferred. In particular, the means by immersion is preferable because it has excellent cooling efficiency. The length of the water cooling zone (water tank) in the case of immersion cooling may be any length as long as the temperature of the monofilament can be sufficiently cooled, but the length of the stretched monofilament immediately before contact with the first rollers is It is preferable to cool the temperature to 80 ° C. or lower. Normally, the length of the water cooling zone is 1
A range of 0 cm to 2 m is used. Further, it is advantageous to use an overflow type water tank structure.

In the present invention, unless the above-mentioned forced cooling is carried out immediately after hot drawing, stains composed mainly of TPO adhere and accumulate on the rollers which the drawn monofilament coming out of the drawing zone first comes into contact with, Problems such as winding of the monofilament around rollers and adhesion of dirt to the obtained monofilament make continuous production extremely difficult.

Generally, the heat-drawn monofilament is heat-set in order to stabilize its dimensions and obtain predetermined physical properties. This heat setting is performed under a temperature of 150 ° C. to 260 ° C. and a relaxation or tension of 0.75 to 1.1 times. In the present invention, when heat setting after hot drawing is performed as described above, before the monofilament immediately after coming out of the heat setting zone first contacts the rollers, forced cooling is performed as in the case immediately after the above hot drawing. It is necessary to do. If this forced cooling is not performed, the monofilaments coming out of the heat setting zone will contact the rollers that come into contact first,
Contamination of TPO adheres and accumulates, causing problems such that the monofilament winds around the rollers and the contamination of the obtained monofilament makes continuous production difficult. The forced cooling method may be the same as the above-described forced cooling immediately after stretching.

The length of the cooling water tank immediately after spinning, the 1st and 2nd stage drawing zone and the heat setting zone can be selected variously, but normally, those having a length in the range of 1 m to 10 m are appropriately used. it can. In the present invention, the above polyester includes various antioxidants, various inactive particles such as titanium oxide, various polymers other than TPO, various metal compounds as catalysts usually used in the production of polyester, and phosphorus compounds used as anti-coloring agents. It may contain a small amount of various dyes and pigments.

[0025]

【Example】

Example 1 Intrinsic viscosity of 0.70 dried under vacuum at 160 ° C. for 8 hours (25 in a mixed solvent of 1: 1 phenol and tetrachloroethane)
Polyethylene terephthalate (measured at ℃) (hereinafter PE
90 parts by weight of a chip, a blend containing ethylene / propylene / diene terpolymer and polypropylene as main components (Mitsui Petrochemical Co., Ltd. "Millastomer" (registered trademark) 5030N, JIS A hardness) 50) 10 parts by weight of chips were mixed in a V-type blender under a nitrogen atmosphere to obtain blended chips.

Next, this blended chip is treated with a pore size of 1.0.
It is supplied to a uniaxial extruder type melt-spinning machine equipped with a spinneret having a discharge hole of mmφ and a hole length of 3.5 mm, and melt-kneaded to melt-spin the monofilament, and immerse it in a water tank containing hot water at 65 ° C for cooling. After that, it was introduced into the first stage stretching zone by heating with warm water at 91 ° C. and stretched 3.5 times. Then, the monofilament after one-stage drawing is heated to 1 by hot air heating.
Stretching was carried out at 25 ° C. so that the total stretching ratio of the first stage and the second stage was 5.5 times.

Then, 10 from the exit of the second drawing zone.
The monofilament exiting the drawing zone was immersed in an overflow type cooling water tank (cooling length 40 cm) arranged at a position of cm to perform forced cooling. Then in the heat setting zone,
Heat setting was performed under the conditions of 215 ° C. and a relaxation rate of 0.91 times, and the pieces were immersed in an overflow type cooling water tank (cooling length 40 cm) arranged at a position 10 cm from the heat setting zone exit, forcibly cooled, and then wound.

The above polyester monofilament can be produced for 24 hours continuously without any trouble, and a polyester monofilament containing 10% by weight of TPO and having excellent abrasion resistance and durability was obtained. After completion of this spinning, the rollers with which the monofilament was first in contact were observed immediately after the exit of the second drawing zone and the heat setting zone, but no stain was observed on the rollers. Comparative Example 1 In Example 1, after the second stage drawing and heat setting,
Spinning was performed under the same conditions except that water cooling was not performed. However, 5 minutes after the start of spinning, immediately after the exit of the heat setting zone, the monofilament first comes into contact with the guide roller, and white dirt begins to adhere to it, and after 30 minutes, dirt of the guide roller is transferred to the wound monofilament. The yarn was interrupted because it was recognized.

Collect the deposit on the guide roller,
When the composition of the deposit was examined by infrared absorption spectrum,
It was found that the deposit was mainly composed of TPO containing a small amount of PET. Immediately after the exit of the second-stage drawing zone, the roller that the monofilament was in contact with was observed, and a small amount of white stain was found to be attached. Example 2 Example 1 except that the second stage drawing temperature was changed to 200 ° C.
When the yarn was made under the same conditions as above, the yarn was made continuously for 24 hours without any trouble, and 10% by weight of TP was used.
A polyester monofilament containing O and having excellent wear resistance and durability was obtained.

After this spinning, the guide rollers with which the monofilament was first in contact were observed immediately after the exit of the second-stage drawing zone and the heat setting zone. No stain was found on both guide rollers. Comparative Example 2 In Example 2, spinning was performed under the same conditions except that water cooling was not performed after the second stage drawing and after heat setting. However, 4 minutes after the start of spinning, white stains began to adhere to the rollers immediately after the second drawing zone, and after 5 minutes, white stains began to adhere to the guide rollers immediately after the exit of the heat setting zone, and 25 minutes later. Since it was confirmed that the dirt on the guide roller was transferred to and adhered to the wound monofilament, the spinning was stopped.

The deposits on the rollers immediately after the second drawing zone and the guide rollers immediately after the exit of the heat setting zone were sampled, and the composition of the deposits was examined by infrared absorption spectrum. As a result, TPO containing a small amount of PET was obtained. It was found to be an adherend containing as a main component. Example 3 In Example 1, the drawing was performed at 190 ° C. in a 5.2-fold single stage, and at the position before the guide roller that first contacted the monofilament after the exit of the drawing zone, an overflow type water-cooled water tank (cooling length 40 cm) was used. ) Was provided and water cooling was performed, and when the yarn was made under the same conditions, continuous 2
The yarn was produced without any trouble for 4 hours to obtain a polyester monofilament containing 10% by weight of TPO and having excellent abrasion resistance and durability.

After the spinning, the guide rollers with which the monofilament was first in contact with each other immediately after exiting the drawing zone and the heat setting zone were observed. No stain was found on both guide rollers. Comparative Example 3 When spinning was performed under the same conditions as in Example 3 except that water cooling was not performed after stretching and heat setting, after 5 minutes from the start of spinning, white stains began to adhere to the roller immediately after the stretching zone, After 6 minutes, white stains began to adhere to the guide roller immediately after the exit of the heat setting zone.
After 6 minutes, it was confirmed that the dirt of the guide roller was transferred to the wound monofilament, and the spinning was stopped.

The deposits on the rollers immediately after the stretching zone and the guide rollers immediately after the exit of the heat setting zone are collected,
When the composition of the deposit was examined by infrared absorption spectrum,
It was found that all of the deposits were mainly composed of TPO containing a small amount of PET.

[0034]

As described above, according to the present invention, when the polyester monofilament mixed with the thermoplastic polyolefin-based elastomer is spun, the monofilament after melt spinning is forcibly cooled immediately after hot drawing and / or heat setting. It prevents the troubles due to the adhesion of stains containing TPO as a main component to the rollers after the process, and enables the industrial production of polyester monofilaments excellent in abrasion resistance and durability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location D02J 1/22 J (72) Inventor Takayuki Yamagami 1 Kawara, Showa-cho, Aichi Prefecture Toray Monofilament Within the corporation

Claims (2)

[Claims] 1. A method for producing a polyester monofilament in which a polyester thermoplastic elastomer is mixed with polyester to be melt-spun into a monofilament, the monofilament is subjected to hot drawing, and immediately after the hot drawing, forced cooling is carried out. 2. The heat-drawn monofilament is heat-set and forcedly cooled immediately after the heat-setting.
A method for producing the described polyester monofilament.