JP2006169680A - Method for producing polyester monofilament for screen gauze and monofilament - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polyester for screen gauze having excellent homogeneity of fiber diameter. <P>SOLUTION: The method for producing the polyester monofilament for screen gauze comprises cooling yarn with cooling wind having 10-35 m/min wind speed at 10-25°C and keeping blow down speed of air current flowing the interior of a yarn spinning duct along a discharged yarn from a spinneret to the take-off direction to 10-25 m/min. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a polyester monofilament for a screen wrinkle. Specifically, the present invention is used for a screen wrinkle in which the uniformity of the diameter used for thermal printing stencil printing in CD printing, graphic printing, and plasma display production is particularly important. The present invention relates to a method for producing a polyester monofilament having a fineness of 40 dtex or less.

  Conventionally, mesh fabrics made of natural fibers such as silk and inorganic fibers such as stainless steel have been widely used as printing screen fabrics. However, in recent years, synthetic fabric meshes that excel in flexibility, durability, and cost performance have been favored. Among them, polyester monofilaments are widely used because they have high dimensional stability and are suitable for screens.

  In recent years, the spread of compact discs (hereinafter abbreviated as CDs) in the home appliance industry, the printing and publication of design products using computer graphics, and the spread of plasma displays are progressing, and synthetic mesh for heat sensitive stencil printing etc. There has been a demand for a screen wrinkle having a finer mesh, less elongation when wrinkled, and excellent dimensional stability and fine diameter uniformity. In particular, in screen printing when a paste used as a dielectric or an electrode is applied to a substrate during plasma display manufacturing, defects such as fine spots on the mesh fabric immediately become printing defects and the commercial value is lost. It is known.

  That is, in order to satisfy the required quality in the above-mentioned applications, a fine yarn, high strength, high modulus, scum generation, etc., as well as screen yarns having excellent diameter uniformity are provided. Is the most important issue.

  Conventionally, various proposals have been made on a method for manufacturing a screen filament monofilament.

For example, a spin draw is obtained by spinning a polyester polymer from a melt spinneret, cooling it, applying an oil agent, taking it up, and taking it up at 1500 m / min or more while continuously drawing it without winding it up ( Patent Document 1). As another proposal, there is a method in which cooling air is applied to the monofilament at a position within 2 m below the spinneret, the undrawn yarn is wound at 600 to 2000 m / min, and then subjected to multistage drawing (see Patent Document 2). . Furthermore, as another proposal, there is a method in which after cooling and solidifying with 25 ° C. chimney air, an aqueous emulsion oil is supplied, and an unstretched monofilament is obtained at a take-up speed of 800 m / min (see Patent Document 3). . These methods are simply direct spinning and drawing methods that have a relatively low winding speed, or focus on only the position and temperature of the cooling air from the spinneret or drawing conditions to obtain monofilament diameter uniformity. Since the fiber diameter uniformity in the unstretched state is insufficient, when measuring the Wooster spots of the obtained monofilament, even if a measurement value of 1.0% or less is obtained For example, it is not possible to eliminate fluctuations in the diameter per 3 m of yarn length in the Wooster waveform, and when the obtained monofilament is made into a screen woven fabric, it is used for printing such as T-shirt printing, which requires relatively little precision. Even if it can be used, it is a screen with insufficient diameter uniformity for use in CD printing, graphic printing, or plasma display printing that requires high precision. A gauze fabric.
JP 2004-52173 A (Claims) Japanese Patent Laid-Open No. 63-262289 (Means for Solving the Problems, page 4, lower right) JP 2000-355830 A (Example 1)

  The present invention solves the above problems, and when used for screen printing when applying paste used as a dielectric or an electrode to a substrate at the time of CD printing, graphic printing, or plasma display production, there is no application defect. It is to provide a method for obtaining a polyester monofilament for screen wrinkles excellent in fine diameter uniformity.

  In order to achieve the above object, according to the present invention, when a polyester monofilament for screen wrinkles having a fineness of 40 dtex or less is melt-spun, the yarn is cooled with cooling air at a temperature of 10 to 25 ° C. and a wind speed of 10 to 35 m / min. A method for producing a polyester monofilament for screen wrinkles, characterized in that the air velocity of the airflow flowing along the discharge yarn from the spinneret in the take-up direction is 10 to 25 m / min.

  The production method of the polyester monofilament for high mesh screen wrinkles of the present invention is such that the temperature and the wind speed of the cooling air used for cooling the yarn, and the blowing air speed flowing along the yarn in the spinning duct are appropriate. CD printing, graphic printing, and screen 紗 printing when applying paste used as a dielectric or electrode on a substrate when manufacturing a plasma display, which has high diameter uniformity that could not be achieved by conventional manufacturing methods. A polyester monofilament for screen wrinkles suitable for high-precision printing can be obtained.

Hereinafter, the present invention will be described in detail.
The polyester monofilament for screen wrinkles in the present invention is obtained by melt spinning using polyethylene terephthalate (hereinafter abbreviated as PET) whose repeating unit is ethylene terephthalate. Although the yarn may be used, the intrinsic viscosity of PET used for the core component of the core-sheath composite yarn or the single component yarn is preferably 0.70 to 1.25 in order to obtain the monofilament strength. Regarding the sheath component of the core-sheath composite yarn, from the viewpoint of suppressing scum at the time of screen knot weaving, copolymerized PET and polyamide are unsuitable and are preferably PET having an intrinsic viscosity of 0.40 to 0.70.

  In addition, the cross-sectional shape of the monofilament in the present invention is that it is easy to obtain stable yarn-making property and screen weaving property, and in order to suppress the occurrence of halation when applying emulsion after weaving and exposing it, That is, it is preferable to have a round cross section in view of the stability of the shape of the lattice space formed by the intersection of the warp yarn and the weft yarn. Further, in order to improve the effect of suppressing the halation, an ultraviolet absorber may be included in the monofilament, and when the ultraviolet absorber is included, in order to suppress the occurrence of scum at the cocoon blades when weaving the screen cocoon. Organic compounds are preferred, and benzotriazole compounds and anthraquinone compounds are preferred. More preferably, an anthraquinone-based yellow pigment is preferably used, which eliminates the need for a dyeing process after weaving screen screen and can reduce the weaving cost.

  In the screen cocooning process, a tension of a certain value or more is required for dimensional stability of the cocoon, and the tension is determined by strength (cN / dtex) × mesh. In order to increase the density, it is generally sufficient to use monofilaments with a fineness. However, the monofilament fineness and the mesh density are not completely inversely proportional, so the finer the fineness, the higher the breaking strength. For this reason, in the case of the monofilament in the present invention, the breaking strength is preferably 5.4 cN / dtex or more, more preferably 6.0 cN / dtex or more. In general, in screen printing, the elongation percentage during printing is about 10%, and in monofilament, the stress during stretching is kept high by 10% from the viewpoint of tension stability and durability. It is important that it is 3.5 cN / dtex or more. More preferably, it is 4.5 cN / dtex or more, More preferably, it is 5.0 cN / dtex or more.

  The fineness of the monofilament used in the present invention is generally less than 40 dtex for monofilaments used in screen printing, especially in screen printing used for CD printing, graphic printing, and paste application to a plasma display substrate. It is conventionally known that it is 18 dtex or less. When melt spinning a monofilament having a fineness of more than 40 dtex, it is very difficult to uniformly solidify the yarn with cooling air, and a water-cooling method in which the discharged yarn is substantially solidified by passing it through the cooling water layer. It must be adopted, and it is difficult to obtain the fine diameter uniformity required for the screen filament monofilament.

  As for the monofilament in the present invention, as a result of various experiments with a screen maker and a plate making maker, in order to eliminate printing defects in the use of a screen 用 い る used for CD printing, graphic printing, and paste application to a plasma display substrate, Wooster spots Of 1.0% or less and the absence of a fluctuation waveform of the diameter of 5% or more per 3 m of yarn length in the Wooster waveform is important. If Worcester spots are 1.0% or less and there is no fine diameter waveform of 5% or more per 3 m of yarn length, CD printing, graphic printing, or electronic substrate will not occur in the coating film thickness during screen printing. Even when used for high-precision printing applications such as circuit printing, and also for applying paste to a plasma display substrate, printing defects due to fluctuations in the yarn diameter do not occur. More preferably, there is no fine diameter fluctuation waveform of 3% or more per 3 m of yarn length with Wooster spots of 0.6% or less.

  In the present invention, the stretching method is not particularly limited as long as the monofilament properties are obtained, and a method of drawing heat treatment after winding up the undrawn yarn may be used. The drawing heat treatment is performed without winding up the undrawn yarn once. Direct spinning drawing may be used. In any stretching method, sufficient strength and stress at 10% elongation can be obtained without variation, so stretching using a hot roller is preferable, and more preferably, one step between the first hot roller and the second hot roller. It is preferable to employ a multistage stretching method in which the eyes are stretched and then the second stage stretching is performed between the second hot roller and the third hot roller or the cooling roller. Further, when winding the drawn yarn, it is preferable to give relaxation between the final hot roller and the cooling roller in order to suppress panic marks when used for the screen yarn weaving.

  In this invention, the cooling wind at the time of cooling the yarn discharged from the nozzle | cap | die is the temperature of 10-25 degreeC, and the wind speed of 10-35 m / min. At temperatures below 10 ° C, condensation occurs in the cooling duct and in the vicinity of the base, causing polymer hydrolysis on the base surface, causing thread breakage, and polymer condensation and air in the condensation inside the cooling duct. As minute dust inside adheres and accumulates and melt spinning continuously, thread breakage over time is induced, or accumulating material falls to the take-up section along with the discharged yarn, causing oil supply unevenness. And induces heat treatment spots. In addition, the cooling air with a high temperature exceeding 25 ° C. or a wind speed lower than 10 m / min is insufficient in cooling effect, so that it becomes difficult to solidify the discharged yarn substantially uniformly, and the cooling duct It is necessary to lengthen the length of the film excessively to increase the time for applying the cooling air, which is inappropriate as an industrial spinning facility. In addition, at wind speeds exceeding 35 m / min, the swaying of the discharged yarn occurs, causing Wooster spots, and yarn contact with the inner wall of the spinning duct, not only worsening the Wooster spots but also causing thread breakage. . The temperature of the cooling air is more preferably 15 to 20 ° C., and the wind speed is 15 to 30 m / min.

  In the present invention, it is important that the air velocity of the airflow flowing along the discharge yarn in the take-up direction from the spinneret in the spinning duct is 10 to 25 m / min. In the case of melt spinning by dry spinning, the yarn discharged from the spinneret is cooled, and then passed through a spinning duct, which is a cylinder or a rectangular cylinder, through the space from the cooling air blowing portion to the take-up portion, and is taken up. As a result of intensive studies by the inventors of the present invention to obtain a high diameter uniformity of the monofilament for screen wrinkles, the static pressure of the spinning section atmosphere is set higher than that of the take-up section in the air-conditioning equipment, and from the base in the spinning duct. It has been found that it is important to generate a blow-down airflow that flows along the discharge yarn in the take-off direction to suppress the swing of the discharge yarn. At this time, when the airflow is less than 10 m / min or when the airflow is generated in the reverse direction, that is, when the airflow is blown from the take-up portion toward the base, the effect of suppressing the swaying of the discharged yarn cannot be obtained. Monofilament diameter uniformity is reduced and thread breakage occurs. In addition, in the air flow exceeding the wind speed of 25 m / min, the air flow turbulence occurs at the upper end where the yarn enters the spinning duct, or the lower end where the yarn comes out to the take-up portion, and the yarn sway increases. Fine diameter uniformity decreases. A more preferable air blowing speed is 15 to 20 m / min.

In the present invention, the method for adjusting the wind speed of the airflow is not particularly limited, but it can be controlled by adjusting the opening area at the lower end of the spinning duct together with the static pressure difference between the spinning portion atmosphere and the take-up portion atmosphere. For example, when the discharge yarn is drawn at 1000 m / min with a static pressure difference of 40 mmHg between the spinning portion atmosphere and the take-up portion atmosphere, the spinning duct opening area is 240 cm ² and the duct outlet opening area is 55 cm ² , so that the wind speed is 15 m / min. Can be obtained. In addition, the blow-down wind speed of the airflow in the present invention indicates that measured at the highest wind speed among the airflow in the spinning duct excluding the spinning duct outlet. For example, when a uniflow chimney is used, the wind speed at which the air blows down is highest at the boundary between the lower end of the chimney duct and the entrance of the spinning duct.

  Hereinafter, the present invention will be described in detail with reference to examples. The evaluation in the examples followed the following method.

1. Solution viscosity (IV)
It calculated from the value measured at 25 degreeC in orthochlorophenol.

2. Tensile strength at break The tensile strength was measured at an initial sample length of 20 cm and a tensile speed of 2 cm / min using a Tensilon tensile tester manufactured by Orientex.

3. Wooster spots 100 monofilament drawn yarns were measured at a speed of 200 m / min, Tensioner force 10, untwisted for 5 minutes (corresponding to a yarn length of 1000 m) using a USTER TESTER4-CX manufactured by Zellberger. The average was used as the measurement result. In addition, all the cut length: HInert's Diagram Mass measured the diameter variation for every 3 m of yarn length, and the maximum was taken as the diameter variation per 3 m of yarn length. It was.
○: Wooster spots less than 1.0% and fine diameter fluctuation less than 4.0% Δ: Wooster spots less than 1.0% and fine diameter fluctuation of 4.0 to 5.0%
X: Wooster spots exceeding 1.0% or fine diameter fluctuation exceeding 5.0% Example 1
Using a PET with IV = 0.80, after discharging the yarn from the die at a spinning temperature of 295 ° C. with a normal spinning machine installed in an atmosphere with a static pressure difference of 40 mmHg between the spinning part and the take-off part, Using a 100cm long front-opening uniflow chimney, the yarn is cooled with cooling air at 25 ° C with a cooling air of 35 m / min, and then the spinning duct inlet opening area is 240 cm ² and the outlet opening area is 55 cm ² and the length is 420 cm. The single-component monofilament yarn passed through a spinning duct with a wind speed of 15 m / min was wound up once with an oil agent at a spinning speed of 1000 m / min.

  This undrawn yarn is stretched 4.20 times between the first hot roller with a surface temperature of 91 ° C. and the second hot roller with a surface temperature of 130 ° C., and 0.6% stretch between the second hot roller and the cooling roller at room temperature. Apply and stretch heat set, fineness is 32. A decitex monofilament was obtained. The breaking strength of the obtained monofilament was 5.5 cN / dtex, the stress at 10% elongation was 3.6 cN / dtex, the Wooster spot was 0.43%, and the variation in the diameter per 3 m of the yarn length was 2.8%. .

Example 2
Using a composite spinning machine consisting of an extruder extruder with a screw outer diameter of φ25 mm manufactured by Nippon Steel Corporation, a composite cross-sectional area ratio using PET with IV = 1.00 and PET with IV = 0.51 as the core polymer After adjusting the polymer discharge amount to 80:20 and discharging the yarn from the die at a spinning temperature of 298 ° C., the inner wall temperature is 300 ° C. and the distance from the yarn is 4.5 cm and the length is 10 cm. After passing through the tropics, the core-sheath type composite monofilament yarn was cooled at a cooling length of 70 cm using a cooling air of 25 m / min at 20 ° C., and passed through a spinning duct set to a wind speed of 20 m / min of the downdraft. The undrawn yarn was wound up once at a spinning speed of 850 m / min after the oil agent was applied.

  This undrawn yarn is 4.39 times between the first hot roller having a surface temperature of 90 ° C. and the second hot roller having a surface temperature of 100 ° C., and 1.between the second hot roller and the third hot roller having a surface temperature of 200 ° C. A composite monofilament with a fineness of 12.0 dtex was obtained by applying 4.29% relaxation between the third hot roller and the cooling roller having a surface temperature of room temperature of 07 times and setting the stretched heat.

  The breaking strength of the obtained monofilament was 7.1 cN / dtex, the stress at 10% elongation was 5.5 cN / dtex, the Wooster spot was 0.32%, and the variation in the diameter per 3 m of the yarn length was 2.1%. .

Example 3
Using a PET of IV = 0.680 containing 0.6% of anthraquinone yellow YELLO # 147 in the PET sheath component of IV = 0.780 as the core polymer, the polymer has a composite cross-sectional area ratio of 80:20 Spinning after adjusting the discharge rate and discharging the yarn from the die at a spinning temperature of 295 ° C., cooling at a cooling length of 100 cm using a cooling air of 10 m / min at 10 ° C., and spinning down to an air flow of 10 m / min. The core-sheath type composite monofilament yarn passed through the duct was once wound up with an unstretched yarn at a spinning speed of 1000 m / min after applying the oil.

  This undrawn yarn has a 4.43 times relaxation between the first hot roller with a surface temperature of 90 ° C and the second hot roller with a surface temperature of 130 ° C, and 1.35% relaxation between the second hot roller and the cooling roller at room temperature. Application and stretching heat setting were performed to obtain a composite monofilament having a fineness of 13.0 dtex. The breaking strength of the obtained monofilament was 5.8 cN / dtex, the stress at 10% elongation was 4.3 cN / dtex, the Wooster spot was 0.79%, and the variation in the diameter per 3 m of the yarn length was 4.3%. .

Example 4
The fineness is 32. in the same manner as in Example 1 except that the opening area of the duct is adjusted so that the blown-down air speed in the spinning duct is 25 m / min. A decitex monofilament was obtained. The breaking strength of the obtained monofilament was 5.5 cN / dtex, the stress at 10% elongation was 3.6 cN / dtex, the Wooster spot was 0.90%, and the variation in the diameter per 3 m of the yarn length was 4.7%. .

Example 5
Using PET of IV = 0.780 and PET of IV = 0.51 as the core polymer, adjusting the polymer discharge amount so that the composite cross-sectional area ratio is 80:20, and starting from the die at a spinning temperature of 295 ° C. After discharging the yarn, a core-sheath type composite monofilament yarn that was cooled at a cooling length of 70 cm using a cooling air of 20 m / min at 10 ° C. and passed through a spinning duct with a blowing air speed of 15 m / min, After applying the oil agent, the surface temperature was picked up by a cooling roller having a room temperature of 600 m / min, and subsequently 4.16 times between the first hot roller having a surface temperature of 90 ° C. and the second hot roller having a surface temperature of 100 ° C., the second hot Set the stretching heat to 1.07 times between the roller and the third hot roller with a surface temperature of 200 ° C, and 3.15% between the third hot roller and the cooling roller with a surface temperature of room temperature. To obtain a composite monofilament having a fineness of 13.0 dtex at a spinning stretching method.

  The breaking strength of the obtained monofilament was 6.2 cN / dtex, the stress at the time of 10% elongation was 5.4 cN / dtex, the Wooster spot was 0.45%, and the variation in the fiber diameter per 3 m of the yarn length was 3.8%. .

Comparative Example 1
A composite monofilament was obtained in the same manner as in Example 5 except that the cooling air temperature was 5 ° C. Although there was no problem with the breaking strength and 10% elongation stress of the monofilament obtained, the fluctuation of the diameter per Worm spot 1.00% and yarn length 3m was 6.2%, and the cooling air temperature was excessively low. In addition, condensation occurs in the spinning duct, and a large amount of PET sublimation accumulated on the inner wall of the spinning duct while continuous spinning is observed. Was found. Due to the condensation in the duct, it was found that the PET sublimated product reached the drawing process together with the yarn and induced Wooster spot deterioration due to the drawing spots.

Comparative Example 2
Except for the cooling air temperature being 30 ° C. A single component monofilament was obtained in the same manner as in Example 4. The obtained monofilament has a breaking strength of 5.2 cN / dtex, a 10% elongation stress of 3.4 cN / dtex, a Wooster spot of 1.28%, a fiber diameter variation per 3 m of yarn length of 7.1%, and a uniform fiber diameter. Became inferior.

Comparative Example 3
A composite monofilament was obtained in the same manner as in Example 3 except that the cooling air speed was set at 5 m / min. However, yarn breakage frequently occurred due to insufficient cooling, and it was impossible to collect substantially undrawn yarn. Met.

Comparative Example 4
A composite monofilament was obtained in the same manner as in Example 2 except that the wind speed of the blown-down airflow was 5 m / min. During spinning, the yarn sway increased and yarn breakage occurred due to yarn contact with the spinning duct. Moreover, although there was no problem in breaking strength and 10% elongation stress of the obtained monofilament, the fluctuation of the diameter per 3 m of yarn length was 12.1 while the ratio of Wooster spots was 0.93% and 1.0% or less. %, And the fiber diameter uniformity was extremely inferior.

Comparative Example 5
A single component monofilament was obtained in the same manner as in Example 1 except that the wind speed of the blown-down air flow was 35 m / min. Although there was no problem with the breaking strength and the stress at 10% elongation of the obtained monofilament, Worcester spots were 3.21%, and the variation in the diameter per 3 m of the yarn length was 15.1%. It became a thing.

Claims (2)

  When melt spinning a screen monofilament polyester monofilament having a fineness of 40 dtex or less, the yarn is cooled with cooling air at a temperature of 10 to 25 ° C. and a wind speed of 10 to 35 m / min, and the inside of the spinning duct is discharged from the spinneret in the take-off direction. A method for producing a polyester monofilament for screen wrinkles, characterized in that the wind speed of the airflow flowing along the screen is 10 to 25 m / min.   The polyester monofilament for screen wrinkles obtained by the production method according to claim 1, wherein Worcester spots are 1.0% or less and there is no fine diameter fluctuation waveform of 5% or more per 3 m of yarn length in the Wooster waveform.