JP4934853B2 - Method for producing fluorine resin monofilament - Google Patents

Description

In the present invention, the excellent heat resistance, chemical resistance, solvent resistance, electrical characteristics, friction characteristics, non-adhesiveness, weather resistance, etc. of the fluorine-based resin can be fully exhibited, and the wire diameter in the length direction Fluctuation is much smaller than conventional monofilaments made of ethylene-tetrafluoroethylene copolymer, and effectively suppresses the occurrence of misalignments such as streaks, stripes, steps, etc. when used on at least part of industrial fabrics ethylene can be - are those concerning the Monofiramen bets manufacturing how consisting tetrafluoroethylene copolymer.

  Conventionally, monofilaments made of thermoplastic resins called general-purpose engineering plastics or super engineering plastics such as polyamide resins, polyester resins, and polyphenylene sulfide resins have excellent characteristics such as heat resistance, strength, and rigidity. It has been preferably used for industrial materials.

  In recent years, fluorine resins having characteristics such as excellent heat resistance, chemical resistance, solvent resistance, electrical characteristics, friction characteristics, non-adhesiveness, and weather resistance have attracted attention, and monofilaments made of polyvinylidene fluoride resin, etc. However, it is preferably used for fishery materials.

  On the other hand, in the field of industrial textiles, there has been an increasing demand for monofilaments made of fluorine-based resins having excellent characteristics, but in particular, monofilaments used for textile applications for papermaking tools in the papermaking industry obtain the homogeneity of the textiles. Therefore, in particular, uniformity of the wire diameter in the length direction is required, and various studies have been made in the past to obtain a monofilament with small wire diameter fluctuation.

  As prior art relating to such monofilaments having small wire diameter fluctuations, (A) monofilaments free from yarn unevenness obtained by performing cooling uniformly and a method for producing the same (for example, see Patent Document 1), and (B) wire diameter fluctuation rate A core-sheath type composite fiber made of a molten liquid crystalline polyester having a small size and a method for producing the same (for example, see Patent Document 2) have already been proposed.

  In addition, (C) a high melting point monofilament having a small wire diameter variation rate obtained by mist cooling and a method for producing the same (for example, see Patent Document 3), and (D) a polyolefin monofilament having a small wire diameter variation rate obtained by mist cooling and A manufacturing method thereof (for example, see Patent Document 4) has already been proposed.

  However, although the conventional techniques proposed in the above (A), (B), (C) and (D) are all expected to give the desired characteristics, the paper industry In applications where a smaller variation in wire diameter is required, such as monofilaments used in textile applications for papermaking tools, the effects are not necessarily satisfactory.

Moreover, even if a fluorine-based resin, particularly an ethylene-tetrafluoroethylene copolymer, is applied to these conventional techniques, it is possible to obtain a monofilament in which the wire diameter variation rate in the length direction of the wire diameter is suppressed to 5% or less. could not.
Japanese Patent Laid-Open No. 11-93015 JP-A-9-296324 JP 2001-279522 A JP 2002-88568 A

  The present invention has been achieved as a result of examining the solution of the problems in the above-described prior art as an object.

Therefore, the object of the present invention is to display the characteristics such as excellent heat resistance, chemical resistance, solvent resistance, electrical characteristics, friction characteristics, non-adhesiveness, weather resistance, etc. possessed by the fluorine-based resin without length. The wire diameter fluctuation in the direction is much smaller than that of the conventional monofilament made of ethylene-tetrafluoroethylene copolymer, and when used in at least part of industrial fabric, streaks, streaks, steps, etc. are generated. ethylene can be effectively prevented - to provide a manufacturing how the Monofiramen bets consisting tetrafluoroethylene copolymer.

In order to achieve the above object, the method for producing a fluorine-based resin monofilament according to the present invention comprises a spinning yarn from directly under a die surface to a cooling medium bath when melt spinning and cooling an ethylene-tetrafluoroethylene copolymer. A cylindrical body is disposed in the passage so that at least its lower surface is immersed in the cooling medium, and an inert gas is circulated into the cylindrical body, and the spun yarn melt-extruded from the die is immediately passed through the cylindrical body. Then, it is led to a cooling medium bath and cooled, and then the obtained undrawn yarn is taken up at a speed of 5 to 15 m / min, and subsequently drawn or drawn / heat set in multiple stages of at least one stage. The final take-up speed is 25 to 75 m / min.

The fluorine-based resin monofilament made of an ethylene-tetrafluoroethylene copolymer obtained by the production method of the present invention has a dramatic change in the diameter in the length direction as compared with a conventional monofilament made of an ethylene-tetrafluoroethylene copolymer. Because it has been improved, it is possible to effectively suppress the occurrence of misalignment such as streaks, stripes, and steps when using industrial fabrics, and the excellent heat resistance and chemical resistance of fluorine-based resins. In addition, it is possible to obtain industrial fabrics, particularly papermaking tool fabrics, filter fabrics, and belt fabrics, which maintain good effects such as solvent resistance, electrical properties, friction properties, non-adhesiveness, and weather resistance.

  The present invention is described in detail below.

  The monofilament made of the ethylene-tetrafluoroethylene copolymer of the present invention (hereinafter referred to as ETFE monofilament) has a linear diameter fluctuation rate of 5% or less, which is extremely small compared to a conventional ETFE monofilament. It is.

  Here, the variation rate (%) in the length direction of the ETFE monofilament of the present invention is the measurement speed of the monofilament sample using an outer diameter measuring machine according to an Anritsu laser outer diameter measuring machine KG601A. The wire diameter was measured under the conditions of 15 m / min, measurement interval 0.1 sec / time, and 1024 measurement points, and further obtained using a data processor according to KEYENCE data processor NR-250 & PC. .

  In this measurement method, the outer diameter of the monofilament is measured by laser scattered light, including the major and minor diameters, and the variation in the diameter of the conventional multifilament is measured by the variation in the cross-sectional area obtained from the change in the dielectric constant. It is different from the method.

  Next, the measurement condition is that the outer diameter of the monofilament is measured once every about 2.5 cm in the length direction over a length of about 25 m, and the data for 1024 measurement points is processed to obtain the standard deviation (σ ) And the wire diameter variation rate (%) expressed as a coefficient of variation [standard deviation (σ) / average value × 100] defined in JIS-Z8101-1.

  It should be noted that the wire diameter variation rate in the length direction of the ETFE monofilament of the present invention measured by such a measurement method is 5% or less, preferably 4% or less, more preferably 3% or less.

  As described above, the ETFE monofilament of the present invention having a very small wire diameter variation rate can effectively suppress the occurrence of misalignment such as streaks, stripes, steps, etc., when used as an industrial fabric. Can be preferably used for various industrial textile applications, which can be preferably used as a papermaking tool fabric, a filter fabric, and a belt fabric, and in that case, it has an unprecedented superiority. An effect can be expressed.

  The polymer that forms the ETFE monofilament of the present invention is not particularly limited as long as it is an ethylene-tetrafluoroethylene copolymer resin that satisfies the above-described monofilament characteristics.

  The ethylene-tetrafluoroethylene copolymer resin used in the present invention includes various kinds of pigments, dyes, light-resistant agents, ultraviolet absorbers, antioxidants, crystallization inhibitors, plasticizers, and the like as necessary. Additives can be added in the polymerization process, after polymerization, or just before spinning as long as the desired performance is not impaired.

  The ETFE monofilament of the present invention having the above characteristics can be efficiently produced by the method described below.

  First, when melt spinning the ETFE monofilament, an ETFE resin is supplied to an extruder type spinning machine having a metering gear pump and a spin block at the tip, melted and kneaded at a spinning temperature of 285 to 325 ° C., and then melted. Is melt extruded from the spinneret.

  When the melt-extruded spun yarn is guided to the cooling medium bath and cooled, the tube is so arranged that at least the lower surface thereof is immersed in the cooling medium in the spun yarn passage from just below the base surface to the cooling medium bath. An inert gas is circulated through the cylindrical body, the spun yarn is immediately cooled through the cylindrical body to the cooling medium bath, and the undrawn yarn obtained is then cooled. An undrawn yarn is obtained by taking up at a speed of 5 to 15 m / min.

  By allowing an inert gas to flow through the cylindrical body, it is possible to suppress the oxidation of the polymer, reduce heat-denatured foreign matter and the like remaining around the mouthpiece hole, and obtain an unstretched yarn with a stable wire diameter. Become. Further, by using a nickel alloy die for the spinneret, the effect of releasing the heat-denatured foreign matter staying around the die hole is improved.

  In addition, it is important to take the undrawn yarn at a speed of 5 to 15 m / min. If the take-up speed is slower than 5 m / min, the undrawn yarn will meander in the cooling medium bath, and the line-thickness variation will be worsened. This is not preferable because it tends to cause the unstretched yarns adjacent to each other to be fused.

  On the other hand, when the take-up speed of the undrawn yarn is higher than 15 m / min, the undrawn yarn is stretched in the cooling medium bath and the roundness is impaired. Since it tends to be difficult to obtain a monofilament having a diameter, it is not preferable, and an undrawn yarn cannot be cut halfway.

  Next, the obtained undrawn yarn is drawn or drawn / heat set in multiple stages of at least one stage, and the final take-up speed at that time is 25 to 75 m / min to obtain an ETFE monofilament.

  In order to obtain desired strength and heat shrinkage properties, the film is stretched in at least one or more stages. In order to obtain stable stretchability, the stretching temperature is set to a temperature higher than the first stretching temperature, and the total stretching ratio is set to 4.0 to 6.0 times.

  This is because if the draw ratio is too low, it is difficult to obtain the desired strength and heat shrinkage characteristics of the ETFE monofilament, and conversely, if it is too high, it is likely to cause thread breakage, and better heat shrinkage characteristics. In order to obtain, it is preferable that it is 4.5 to 5.5 times.

  Also, if the stretching temperature is too low, high tension is applied during stretching, which tends to cause thread breakage. Conversely, if the stretching temperature is too high, the melting point of the ETFE resin is close, and thread breakage tends to occur in the stretching bath. Must be 80 to 200 ° C., more preferably 70 to 200 ° C.

  Here, the heating medium used in the stretching process may be a substance that can be easily removed from the surface of the ETFE monofilament and that does not essentially give a physical or chemical change to the ETFE monofilament. Any method can be used, but the present invention performs the first-stage stretching at a relatively low temperature, and therefore, a warm water bath or a heated air bath is suitable economically. In addition, as a heat medium used in the second stretching step, generally, a heating apparatus such as a liquid bath filled with an inert liquid having a high boiling point, an air furnace, an inert gas furnace, an infrared furnace, and a high-frequency furnace is used. Is preferred.

  The ETFE monofilament stretched in at least one or more stages is subjected to heat setting treatment as necessary in order to further improve and maintain the desired strength and heat shrinkage properties obtained in the stretching process. Although it is provided, it is necessary that the temperature of this set process be 120 to 240 ° C, and further 140 to 220 ° C is preferable.

  The set magnification is 0.85 to 1.20 times, which is a necessary condition for obtaining desired heat shrinkage characteristics.

  If this set magnification is too low, the thermal shrinkage of the resulting ETFE monofilament will be low, and not only will the industrial fabrics not be stored after heat setting, but also misalignments such as streaks, stripes and steps will easily occur. On the contrary, if the set magnification is too high, thread breakage is likely to occur. Therefore, it is necessary to set the set magnification to 0.90 to 1.05 times, preferably 0.95 to 1.01 times. More preferably.

  Here, as the heating device used in the set processing step, a liquid bath filled with an inert liquid having a high boiling point similar to the above-described second-stage stretching, an air furnace, an inert gas furnace, an infrared furnace, a high-frequency furnace, etc. Can be mentioned.

  Then, the set ETFE monofilament is provided with an oil agent on the surface as needed, and then wound around a winding tool.

  The final take-up speed is preferably 25 to 75 m / min.

  As described above, after drawing the undrawn yarn at a speed of 5 to 15 m / min, the drawing or drawing / heat setting treatment is performed in multiple stages of at least one stage in order to obtain the desired strength and heat shrinkage characteristics. Thus, an ETFE monofilament with a small variation in the wire diameter in the length direction can be obtained.

  This final take-up speed can be obtained by multiplying the undrawn yarn take-up speed by the draw ratio or draw ratio / heat setting treatment ratio, but if the final take-up speed is lower than 25 m / min, it will cause stretch spots and a uniform line. Since it tends to be difficult to obtain monofilaments having a diameter, it is not preferable, and the desired strength and heat shrinkage characteristics tend to be uneven.

  Further, when the final take-up speed is higher than 75 m / min, it is easy to cause thread breakage. To obtain a better uniform wire diameter and desired strength and heat shrinkage characteristics, the final take-up speed is It is preferable that it is 30-65 m / min.

  The ETFE monofilament of the present invention thus obtained has a small wire diameter variation rate that is not found in the conventional ETFE monofilament, so that the ETFE monofilament can be used for at least a part of the industrial fabric.

  In addition, the industrial fabric comprising the ETFE monofilament of the present invention can be used for a papermaking tool fabric, a filter fabric, and a belt fabric. It is possible to maintain a stable woven surface that is less prone to slippage, and easy moldability, chemical resistance, electrical properties, high weather resistance, flame resistance, and safety of ethylene-tetrafluoroethylene copolymer resin Exhibits excellent properties such as non-adhesiveness and secondary processability.

  The ETFE monofilament of the present invention is a single continuous yarn, but it may be a plurality of twisted yarns / heat set as needed, or a single yarn twisted and heat set.

  In addition, the cross-sectional shape of the ETFE monofilament of the present invention can be appropriately selected according to its use and is not particularly limited. For example, the shape is round, elliptical, triangular, T, Y, H, + Multi-leaf shape such as 5 leaves, 6 leaves, 7 leaves, 8 leaves, squares, rectangles, rhombuses, saddles, and horseshoe types can be mentioned, and these shapes are partially modified Also good.

  Furthermore, the diameter of the ETFE monofilament of the present invention can be appropriately selected according to its use and is not particularly limited. For example, as an industrial textile use, the diameter is 0.05 to 1.50 mm. Is mainly used.

Thus, the fluorine-based resin monofilament obtained by the production method of the present invention is extremely useful for various textile applications that require smaller wire diameter fluctuations than conventional ETFE monofilaments.

  Next, although this invention is demonstrated based on an Example, the evaluation of the monofilament in an Example was performed according to the following method.

[Variation rate of wire diameter]
Using an outer diameter measuring machine according to Anritsu laser outer diameter measuring machine KG601A, the outer diameter was measured under the conditions of a measuring speed of 15 m / min, a measuring interval of 0.1 sec / time, and a measuring point of 1024 times. Using a data processor according to NR-250 & PC manufactured by the manufacturer, the wire diameter variation in the length direction of the wire diameter was evaluated, and the result was expressed as a coefficient of variation [standard deviation defined in JIS-Z8101-1. The value represented by (σ) / average value × 100] was defined as the wire diameter variation rate.

[Operability]
The situation at the time of continuous extrusion spinning was observed, and the following three stages were evaluated from yarn breakage and stability of pushing the raw material into the spinning machine.
○: No problem at all, very good,
Δ: There was some yarn breakage but operation was possible.
X: The operability was difficult due to frequent occurrences of thread breakage and indentation failure of raw materials.

[Missing]
For the evaluation of the misalignment of the filter, the obtained filter 1 m ² was visually inspected (streaks, stripes, steps), and the degree of misalignment was evaluated in the following three stages. In addition, (circle) is a level with a favorable appearance quality.
○: Streaks, stripes, steps are unknown
Δ: streaks, stripes, steps are recognized,
X: Generation of streaks, stripes, and steps is remarkable.

[Example 1]
ETFE (Full-on ETFE-C88AXP manufactured by Asahi Glass Co., Ltd.) is used as a fluorine-based resin, which is supplied to an extruder-type spinning machine, melted at a spinning temperature of 315 ° C., and made of a nickel alloy having a pore diameter of 2.0 mm. When spinning the spun yarn melted and extruded from the die through the die at a discharge rate of 12.2 g / min, immediately introduced into a 50 ° C. water bath and cooled, it was applied directly under the die surface to the cooling medium bath. A non-stretched product obtained by disposing a cylindrical body in the spinning yarn passage so that at least the lower surface thereof is immersed in a cooling medium, allowing nitrogen gas to flow through the cylindrical body and taking it up at 12.3 m / min. The yarn was stretched in two stages at stretching temperatures of 90 ° C. and 160 ° C. and a stretching ratio of 4.80 times, and subsequently set processing was performed at a processing temperature of 170 ° C. and a set ratio of 0.93 times. The final speed at that time was 55 m / min, and an ETFE monofilament having a diameter of 0.40 mm and a circular cross section was obtained.

[Example 2]
ETFE (Fullon ETFE-C88AXP manufactured by Asahi Glass Co., Ltd.) is used as a fluorine-based resin, which is supplied to an extruder-type spinning machine, melted at a spinning temperature of 315 ° C., and a spinning made of a nickel alloy having a pore diameter of 0.8 mm. When spinning the spun yarn melt-extruded from the die through a die at a discharge rate of 0.24 g / min and immediately extruded into a 50 ° C. water bath, it is cooled immediately below the die surface into a cooling medium bath. A non-stretched product obtained by placing a cylindrical body in the spinning yarn passage of the tube so that at least the lower surface thereof is immersed in the cooling medium, circulating nitrogen gas into the cylindrical body, and taking it up at 8.2 m / min. The yarn was stretched in two stages at a stretching temperature of 85 ° C. and 140 ° C. and a draw ratio of 4.60 times, and subsequently set processing was performed at a treatment temperature of 150 ° C. and a set ratio of 0.93 times. The final speed at that time was 35 m / min, and an ETFE monofilament having a diameter of 0.07 mm and a circular cross section was obtained.

[Example 3]
ETFE (Fullon ETFE-C88AXP manufactured by Asahi Glass Co., Ltd.) is used as a fluorine-based resin, which is supplied to an extruder-type spinning machine, melted at a spinning temperature of 315 ° C., and a spinning made of a nickel alloy having a pore diameter of 4.5 mm. When spinning the spun yarn that was spun at a discharge rate of 27.1 g / min per single hole through the die and melt-extruded from the die immediately into a 50 ° C. water bath, it was cooled immediately below the die surface into the cooling medium bath. A non-stretched product obtained by disposing a cylindrical body in the spun yarn passage so that at least the lower surface thereof is immersed in the cooling medium, allowing nitrogen gas to flow through the cylindrical body, and drawing at 9.0 m / min. The yarn was stretched in two stages at a stretching temperature of 90 ° C. and 190 ° C. and a draw ratio of 5.30 times, and subsequently a set treatment was performed at a treatment temperature of 225 ° C. and a set ratio of 0.93 times. The final speed at that time was 40 m / min, and an ETFE monofilament having a diameter of 0.70 mm and a circular cross section was obtained.

[Example 4]
ETFE (Fullon ETFE-C88AXP manufactured by Asahi Glass Co., Ltd.) is used as a fluorine-based resin, which is supplied to an extruder-type spinning machine, melted at a spinning temperature of 315 ° C., and a spinning made of a nickel alloy having a pore diameter of 8.0 mm. When spinning the spun yarn that was spun at a discharge rate of 66.9 g / min per single hole through the die and melt-extruded from the die into a 50 ° C. water bath, it was cooled immediately below the die surface and into the cooling medium bath. A non-stretched product obtained by disposing a cylindrical body in the spun yarn passage so that at least the lower surface thereof is immersed in the cooling medium, allowing nitrogen gas to flow through the cylindrical body, and drawing at 9.0 m / min. The yarn was stretched in two stages at a stretching temperature of 90 ° C. and 190 ° C. and a stretching ratio of 4.80 times, and subsequently set processing was performed at a processing temperature of 225 ° C. and a set ratio of 0.93 times. The final speed at that time was 40 m / min, and an ETFE monofilament having a diameter of 1.10 mm and a circular cross section was obtained.

[Comparative Example 1]
In Example 1, an ETFE monofilament having a diameter of 0.40 mm was obtained in the same manner as in Example 1 except that nitrogen gas was not circulated into the cylindrical body.

[Comparative Example 2]
In Example 1, an ETFE monofilament having a diameter of 0.40 mm was prepared in the same manner as in Example 1 except that the take-up speed of the undrawn yarn was lowered to 4.0 m / min and the final speed was lowered to 17.9 m / min. Obtained.

[Comparative Example 3]
In Example 1, an ETFE monofilament having a diameter of 0.40 mm was prepared in the same manner as in Example 1 except that the take-up speed of the undrawn yarn was increased to 17.5 m / min and the final speed was increased to 78.1 m / min. Obtained.

[Comparative Example 4]
An ETFE monofilament having a diameter of 0.40 mm in the same manner as in Example 1 except that the draw ratio was increased from 4.80 times to 6.80 times and the final speed was increased to 77.8 m / min. Got.

  Table 1 also shows the results of the rate of variation of the wire diameter of each ETFE monofilament obtained in Examples 1-4 and Comparative Examples 1-4.

As is clear from the results of Table 1, the ETFE monofilaments (Examples 1 to 4) obtained by the production method of the present invention have extremely small fluctuation rates of the wire diameter in the length direction of 5% or less. is there.

  On the other hand, all of the ETFE monofilaments (Comparative Examples 1 to 4) manufactured by a production method in which the flow of nitrogen gas directly under the die surface, the take-up speed of undrawn yarn, and the final speed of the monofilament do not satisfy the conditions of the present invention are operated. Inferior in properties, the variation rate of the wire diameter in the length direction is large (Comparative Examples 1 and 2), and the yarn is not drawn by being stretched (Comparative Examples 3 and 4). It did not meet.

A plain woven fabric was woven using the ETFE monofilaments of 0.40 mm in diameter obtained in Example 1 and Comparative Examples 1 and 2 for warp and weft, respectively, and this fabric was heat-set at 190 ° C. to give a basis weight of 500 g. / M ² filter was produced, and the filter using the ETFE monofilament of Example 1 as a filter constituent wire, which had a small variation in the diameter in the length direction, did not cause misalignment. In the ETFE monofilaments of Examples 1 and 2, misalignments such as streaks, stripes and steps were observed.

As described above, the ETFE monofilament obtained by the production method of the present invention has a drastic improvement in the wire diameter variation in the length direction as compared with the conventional ETFE monofilament. Further, it is very useful for industrial fabrics such as filter fabrics and belt fabrics.

  Moreover, according to the manufacturing method of the present invention, an ETFE monofilament having a very small wire diameter variation rate in the length direction can be efficiently manufactured.

Furthermore, the industrial fabric using the ETFE monofilament obtained by the production method of the present invention can also be used for a papermaking tool fabric, a filter fabric, a belt fabric, and the like. It is possible to maintain a stable woven surface that is less prone to misalignment such as streaks, stripes and steps on the woven surface, and also has excellent heat resistance, chemical resistance, solvent resistance, and electrical properties possessed by fluorine-based resins. It exhibits the effects such as friction characteristics, non-adhesiveness, and weather resistance.

Claims (1)

When melt-spinning and cooling the ethylene-tetrafluoroethylene copolymer, a cylindrical body is arranged in the spinning yarn passage from directly under the die surface to the cooling medium bath so that at least the lower surface thereof is immersed in the cooling medium. An inert gas is allowed to flow through the cylindrical body, and the spun yarn melt-extruded from the die is immediately led to the cooling medium bath through the cylindrical body to be cooled, and the obtained undrawn yarn is A fluorine-based resin monofilament characterized by being drawn at a speed of 15 m / min and subsequently subjected to stretching or stretching / heat setting treatment in at least one or more stages, and the final take-up speed at that time is 25 to 75 m / min. Manufacturing method.