JP3725064B2 - Polyester monofilament for screens - Google Patents

Description

【００４４】
実施例１、２、３及び４は、紡糸性、及び繊維の特性とも本発明の目的を達成する。比較例１は、海成分比率（ＰＥＴ）の重量比率が大きく、島成分比率（ＰＥＮ）の重量比率が小さいため、強度及び弾性率が不十分であり、筬摩耗破断回数が低い、即ち耐摩耗性が低い。比較例２は、海成分比率（ＰＥＴ）の重量比率が小さく、島成分比率（ＰＥＮ）の重量比率が大きいために、複合断面形成が不安定で、繊度斑を起こし、かつ島成分（ＰＥＮ）単独断面の発生により、デラミ現象が顕著で、紡糸性も悪く、筬摩耗破断回数が著しく低くなった。比較例３は、島数が１の単純シースコア断面であるため、島成分（ＰＥＮ）による応力分散効果が不充分で、繊維表面層を形成する海成分（ＰＥＴ）に応力が集中し、デラミ発生指数が低く、筬摩耗破断は試験初期の回数で発生している。比較例４は、紡糸速度が５０００ｍ／分未満のため、強度、弾性率、及び、熱収縮性即ち寸法安定性が不充分で、筬破断回数が低かった。比較例５は、低紡速で一旦巻き取った糸を、２段延伸して熱処理を施したが、延伸性が不充分で均一に延伸できる倍率が比較的小さいために、配向が不十分で、強度、弾性率及びデラミ発生指数が低く、筬摩耗性が悪い。
【００４５】
【発明の効果】
本発明では、ポリエチレンテレフタレート系ポリエステル（Ｓ）を海成分、ポリエチレンナフタレート系ポリエステル（Ｉ）を島成分とし、（Ｉ）が４０〜９０ｗｔ％、（Ｓ）が１０〜６０ｗｔ％、島成分の数が４以上である海島型複合繊維を、５０００ｍ／分以上の速度で紡糸して製造することによって、耐摩耗性、耐フィブリル化、寸法安定性、高弾性、高強度、及び紡糸性に優れ、ハイメッシュスクリーン紗用途に適した超細繊度のモノフィラメントを、安定した操業性で、生産効率良く、提供することが可能である。
【図面の簡単な説明】
【図１】筬摩耗破断回数を測定するために用いた装置の概略図。
【符号の説明】
１ モノフィラメント
２ 荷重用分銅
３ 筬
４ 上部櫛歯
５ 下部櫛歯[0001]
BACKGROUND OF THE INVENTION
The present invention has a fineness useful as a screen reed, particularly a high mesh screen reed, which has excellent tensile strength, high elastic modulus, friction resistance during weaving and use, etc., and high production efficiency. It relates to a cross-sectional polyester monofilament.
[0002]
[Prior art]
Although the screen cage is used in the field of electronics such as printing of electronic circuits, there is an increasing demand for improvement in printing accuracy. Therefore, a high-strength and high-elasticity screen cage is required. In addition, since a high-mesh type is required, the monofilament constituting the screen basket should be fine. Conventionally, stainless steel screens have been used, but there is a problem that durability is insufficient.
[0003]
In order to remedy this problem, various types of screen cages made of synthetic fibers have been proposed. For example, a high-strength, high-elasticity fiber made of a liquid crystalline polymer has improved durability although it is slightly inferior in dimensional accuracy to stainless steel. However, in this case, since the molecular chain is very easily oriented in the fiber axis direction, there is a problem that fibrillation easily occurs due to friction.
[0004]
In order to improve the problem of fibrillation, screens using fibers made of polyethylene terephthalate, which is a non-liquid crystalline polymer, are disclosed in JP-A-62-210495, JP-A-62-215013, and JP-A-2- No. 127513 is proposed. However, since the fibers have low strength and elastic modulus, the durability and dimensional accuracy of the screen ridge are insufficient, and it is difficult to obtain a high-density screen ridge due to insufficient weaving property under high tension. There is a problem that.
[0005]
On the other hand, screen ridges using fibers made of polyethylene naphthalate, which is a non-liquid crystalline polymer, have been proposed in Japanese Patent Application Laid-Open No. 4-100914, Japanese Patent Application No. Hei 2-272387, etc. It is said that a high-density screen with a balance between strength and elastic modulus can be obtained. However, according to our study, it has been found that there is a problem that scum is likely to occur when weaving into a high-density screen ridge. This is presumed to be derived from the fact that polyethylene naphthalate has a molecular structure having liquid crystal properties. Japanese Patent Application Laid-Open No. 2000-336523 describes a modified polyethylene naphthalate monofilament and a method for producing the same, but it has not been sufficient.
[0006]
Further, Japanese Patent Application Laid-Open No. 2-80640 proposes a screen cage using a multi-core composite fiber in which liquid crystalline aromatic polyester is used as 36 island components and non-liquid crystalline polyethylene terephthalate is used as a sea component. . However, since this fiber is manufactured by heat-treating an as-spun yarn spun at a high speed of about 3500 m / min in a package, the heat treatment effect differs depending on where the yarn is present in the winding package. There is a problem that there is a large variation in quality at the end and beginning of winding and between winding packages.
[0007]
The inventors of the present invention previously described in Japanese Patent Application No. 2000-288400 as having excellent weaving properties, durability and dimensional accuracy, and mainly comprising an island component having polyethylene naphthalate as a main component and polyethylene terephthalate as a main component. We proposed a monofilament for a screen cage of a predetermined sea-island type composite fiber consisting of However, due to the need for screen printing with higher density and higher quality, more advanced polyester monofilaments are required for high elasticity and wear resistance.
[0008]
[Problems to be solved by the invention]
The present invention provides an ultrafine monofilament that is excellent in abrasion resistance, fibrillation resistance, dimensional stability, high elasticity, high strength, and spinnability, and suitable for high mesh screen use, with high production efficiency. With the goal.
[0009]
[Means for Solving the Problems]
The present invention is a polyester monofilament spun at a speed of 5000 m / min or more, wherein the polyester monofilament comprises a polyester (S) comprising a polyethylene terephthalate component of 85% or more as a sea component and a polyethylene naphthalate component from 85% or more. Polyester (I) is an island component, (S) is 10 to 60 wt%, (I) is 40 to 90 wt%, and the number of island components is 4 or more, and the fineness is 7. It is a polyester monofilament for screen wrinkles characterized by being 0 dtex or less.
[0010]
The polyester monofilament for screen wrinkles of the present invention preferably has a strength of 4.4 cN / dtex or more, an elastic modulus of 130 cN / dtex or more, a 150 ° C. dry heat shrinkage of 4% or less, and a delamination generation index of 10% or more.
[0011]
Furthermore, the present invention is a screen basket made of the polyester monofilament.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
When polyethylene naphthalate fibers are used alone as screen wrinkles, the polyethylene naphthalate polymer exhibits a liquid crystal polymer-like melt spinning behavior, so that the fibers are highly oriented in the fiber axis direction, the strength in the fiber axis direction and the fiber cross-sectional direction, and The elastic modulus difference is large. As a result, it was impossible to fundamentally solve wrinkle wear, scum generation and delamination phenomenon due to interface peeling. Therefore, in order to take advantage of the high strength, high elasticity and dimensional stability of polyethylene naphthalate and to provide excellent wear resistance, sea-island type composite fiber using polyethylene terephthalate as the sea component and polyethylene naphthalate as the island component. Moreover, it is optimal that the yarn is spun at a high speed of 5000 m / min or more.
[0013]
The island component of the sea-island composite fiber of the present invention is made of polyester (hereinafter referred to as “polyester I”) in which 85 mol% or more is polyethylene naphthalate. Examples of polyethylene naphthalate include polyethylene-2,6-naphthalate. Various additives such as a stabilizer, a matting agent, a colorant, and an ultraviolet absorber may be added to the polyester I as long as the object of the present invention is not impaired.
[0014]
Intrinsic viscosity after melt extrusion of polyester I (measured solvent is a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio), measured temperature is 20 ° C., measured by the Ubbelohde method) is in the range of 0.50 to 0.70. It is preferable that it exists in. When the intrinsic viscosity is within this range, the high-speed spinnability is excellent, and the strength of the obtained filament is sufficient.
[0015]
The sea component of the sea-island composite fiber of the present invention is made of polyester (hereinafter referred to as “polyester S”) in which 85 mol% or more is polyethylene terephthalate. Various additives such as a stabilizer, a matting agent, a colorant, and an ultraviolet absorber may be added to the polyester S as long as the object of the present invention is not impaired.
[0016]
The intrinsic viscosity of the polyester S after melt extrusion (measurement solvent is a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio), measurement temperature 20 ° C., measured by the Ubbelohde method) is in the range of 0.5 to 0.9. In this range, the spinnability is excellent and the strength of the filament obtained is sufficient.
[0017]
The weight ratio of polyester I and polyester S in the monofilament is preferably in the range of 40 to 90 wt% for polyester I and 60 to 10 wt% for polyester S. When the polyester I is 40 wt% or less, the strength of 4.4 cN / dtex or more cannot be achieved. On the other hand, when the polyester I is 90 wt% or more, it becomes difficult to form a cross-section of the sea island, and the island component alone or the discharge is unstable. Spinnability may deteriorate.
[0018]
The number of islands in the sea-island type composite fiber of the present invention is plural. In the case of one island, that is, a sea core cross section, the stress applied to the fiber surface due to friction during weaving or use does not disperse inside the fiber, but concentrates on the surface layer and the PEN / PET interface. The occurrence index becomes smaller. Therefore, the number of islands is preferably a plurality, particularly 4 or more, and the number of islands is preferably large according to the space in the base. The preferred number of islands is 4 to 36, and the more preferred number of islands is 8 to 30 in terms of achieving both high elasticity and yarn-forming properties.
[0019]
The cross-sectional shape of the island component is not particularly limited, but a generally round cross-section is usually employed from the viewpoint of yarn production. In addition, each of the island components may be independent or a part of the island components may be connected to other island components.
[0020]
The cross-sectional shape of the composite fiber is not particularly limited, but may be any shape of a round, triangular, square, multi-loval cross section, and even a flat cross section.
[0021]
In the present invention, polyester (S) having a polyethylene terephthalate component of 85% or more is a sea component, polyester (I) having a polyethylene naphthalate component of 85% or more is an island component, and (S) is 10 to 60 wt%, ( It is necessary to spin a polyester monofilament of sea-island type composite fiber having an I) of 40 to 90 wt% and an island component number of 4 or more at a speed of 5000 m / min or more.
[0022]
It is important that the spinning speed is 5000 m / min or more. In particular, spinning at 5000 m / min or more and 7500 m / min or less is preferable. More preferably, it is 6000 m / min or more. By spinning at 5000 m / min or more, the wear resistance is improved and the occurrence of the delamination phenomenon can be reduced. On the other hand, a spinning speed that is too high is not realistic at this stage.
[0023]
The fineness of the monofilament of the present invention is 7.0 dtex or less. When the fineness exceeds 7.0 dtex, it is difficult to obtain a required ultra-high mesh screen wrinkle. Conventionally, high mesh screen wrinkles using high-strength monofilaments of about 13.0 dtex to 31.0 dtex have been provided, but high-strength monofilaments of 7.0 dtex or less are required for higher-precision printing. .
[0024]
The strength of the monofilament of the present invention is 4.4 cN / dtex or more. When a monofilament of 7.0 dtex or less is used, the fineness is reduced and the overall strength is weakened. However, the strength of the monofilament is suitably 4.4 cN / dtex or more. If it is less than 4.4 cN / dtex, the strength of the screen wrinkles is insufficient at the time of weaving or tensioning, and yarn breakage tends to occur.
[0025]
The elastic modulus of the monofilament of the present invention is 130 cN / dtex or more. When the elastic modulus is 130 cN / dtex or less, the rigidity is insufficient, and as a result of repeated use, the heel itself sags or breaks, making high-quality printing difficult.
[0026]
The elongation of the monofilament of the present invention is not particularly limited, but is preferably 10% or more and 20% or less. If it is 10% or less, the strength is low, the optimum spinning conditions are not adopted, and the spinning condition is poor. On the other hand, a fiber having an elongation of 20% or more is difficult to be compatible with an elastic modulus that satisfies the requirements of the present invention.
[0027]
The delamination generation index of the present invention is preferably 10% or more, particularly 13 to 30%. When the delamination generation index is 10% or more, when weaving an ultra-high mesh screen wrinkle, the fiber does not break even with a bending compression load at a minute interval that the fiber receives. be able to. Moreover, the durability of the resulting screen bag is also good.
[0028]
Delamination generation index is a ring when a monofilament intersects to create a ring of any diameter, gradually tightening both ends of the filament to reduce the diameter of the ring, and a kink band is generated on or inside the monofilament The ratio of the diameter of the monofilament to R when the diameter of R is R (delamination generation index (%) = (D / R) × 100). This index indicates the resistance of fiber structure destruction to compressive deformation. The larger the value, the less likely the fiber structure breaks even if the fiber is distorted, and the delamination phenomenon (interfacial delamination) occurs. It is difficult and therefore shows excellent fibrillation resistance.
[0029]
The delamination generation index indicates compressive shear modulus and correlates with the fiber crystal form. The more the crystals inside the fiber are oriented in the fiber axis direction, the higher the tensile strength and tensile modulus of the fiber, but the strength and elastic modulus in the direction perpendicular to the fiber axis, and the compressive shear modulus decrease, and the fiber axis direction On the other hand, stress concentration points tend to occur in a direction inclined by 45 °. In order to reduce this, interfacial peeling occurs in the crystal interface direction of the fiber, that is, in the fiber axis direction. Therefore, it is considered that the smaller the fiber orientation in the fiber axis direction, that is, the greater the delamination generation index, the better the abrasion resistance and fatigue resistance during weaving and use.
[0030]
The polyester monofilament of the present invention has a dry heat shrinkage of 150 ° C. of 4% or less. In the case of 4% or more, since the heat setting property is insufficient, there is a shrinkage behavior due to heat applied at the time of printing, a phenomenon in which wrinkles are irregularly undulated, and high-quality printing is impossible.
[0031]
The composite polyester monofilament of the present invention can be produced by the following method. That is, polyethylene terephthalate (polyester S) and polyethylene naphthalate (polyester I) are melted with separate ruders, introduced into a sea island forming die, and the intrinsic viscosity of the extruded yarn after extrusion is 0 for polyethylene terephthalate (polyester S). A monofilament of 0.5 to 0.9 and polyethylene naphthalate (polyester I) of 0.5 to 0.7 is wound up through a pair (two) of goded rollers of 5000 m / min or more.
[0032]
Furthermore, when the monofilament extruded from the die is cooled by the single blow cooling device, it is preferable to blow the cooling air at a speed of 0.3 m / min or less. By spraying at a cooling rate of 0.3 m / min or less, non-uniform cooling is eliminated, and apparent crimp is not generated in the obtained monofilament, which is preferable. If the monofilament has an actual crimp, it is not preferable because a uniform tension cannot be applied in the process of tensioning the screen wrinkle, and spots such as yarn breakage and further problems such as yarn breakage occur.
[0033]
It is preferable to apply the oil agent to the cooled monofilament 1 m or more below the die surface. In the monofilament region located less than 1 m from the die surface, the monofilament temperature is above the glass transition point. Therefore, when an oil agent is applied in this region, non-uniform cooling occurs, and crimping occurs in the obtained monofilament.
[0034]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited by these. The characteristic values in the following examples are measured by the following methods.
[0035]
(1) Intrinsic viscosity after melt extrusion (η)
The intrinsic viscosity (η) was measured by the Ubbelohde method at 20 ° C. in a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio) of a polyester melted and extruded from a die by a conventional method.
[0036]
(2) Strength, elongation, elastic modulus Using an autograph manufactured by Shimadzu Corporation, an initial load of 1/30 cN / dtex of fineness was applied to a fiber having an initial test length of 200 mm, and a tensile test was performed at a speed of 200 mm / min. The breaking strength and breaking elongation were determined. Furthermore, the elastic modulus was determined from the initial slope of the strong elongation curve.
[0037]
(3) A 150 ° C. dry heat shrinkage casserole is prepared, and an initial test length is measured by applying a load of (cassette dtex × 2/30) g. After removing the load, it is heat-treated for 30 minutes in a dryer controlled at 150 ° C. and then returned to room temperature (20 ° C.). After the yarn temperature becomes equal to room temperature, a load of (cassette dtex × 2/30) g is applied again, and the length after heat treatment is measured. The shrinkage rate is calculated from both test lengths.
[0038]
(4) Delamination generation index Monofilament diameter D is measured with a micrometer. On the other hand, under an optical microscope, monofilaments are crossed to create a circle of any size. Next, while observing the point (P) located on the opposite side of the circle at the intersection (X), both ends of the monofilament are gradually tightened to make the circle smaller. At that time, the diameter (R) of a circle when a kink band (observed as a whitening phenomenon) generated at an angle of about 45 ° with the fiber axis direction is confirmed on the surface of the fiber at the observation point is measured. The delamination occurrence index was calculated by the following formula.
Delamination occurrence index (%) = (D / R) × 100
[0039]
(5) Number of wrinkle wear ruptures This was performed by the method disclosed in Japanese Patent Laid-Open No. 2000-336523. FIG. 1 is a schematic view of an apparatus used when measuring the number of wrinkle wear fractures. A weight 2 of {0.2 × (dtex of monofilament 1)} g is applied to the monofilament 1, and threading is performed on the teeth of the heel 3 which is 300 teeth / inch (118 teeth / cm). The monofilament 1 is straightened in the vertical direction and placed between the upper comb teeth 4 and the lower comb teeth 5. Next, in the upper comb teeth 4, the monofilament 1 is placed by shifting by 40 teeth (about 4.5 mm) of the collar 3 from the vertical direction to the right side. By driving the motor, the rod 3 moves up and down at a speed of 140 rotations / minute with a width of 10 cm, thereby rubbing the monofilament 1 in contact with the teeth. The number of times until the monofilament 1 is cut by friction is measured as the number of wrinkle wear fractures.
[0040]
(6) Spinnability It is determined how many times the yarn breakage occurs during the continuous spinning operation for 24 hours. If it was 0 to less than 2 times during 24 hours of operation, it was evaluated as ◯, and if it was twice or more during 24 hours of operation, it was evaluated as x.
[0041]
[Examples and comparative examples]
The polyethylene terephthalate (polyester S) having an intrinsic viscosity of 0.65 is used as the sea component, and the polyethylene naphthalate (polyester I) having an intrinsic viscosity of 0.65 is used as the island component. Table 1 also shows the characteristic values of each monofilament manufactured by winding at the spinning speed.
[0042]
Using a die with a hole diameter of 2 holes and a diameter of 0.7 mmφ, the molten polymer is extruded, and a length of 1 m below is directly below the nozzle, and a cooling air of 25 ° C. is blown at a rate of 0.2 m / min. After cooling the strip, oil is applied to the polymer at a location 1 m or less from directly under the base, taken up by the goded roller, and then separated through the second goded roller, and taken up by a winder. It was.
[0043]
[Table 1]

[0044]
Examples 1, 2, 3 and 4 achieve the object of the present invention in terms of spinnability and fiber properties. In Comparative Example 1, since the weight ratio of the sea component ratio (PET) is large and the weight ratio of the island component ratio (PEN) is small, the strength and the elastic modulus are insufficient, and the number of wrinkle wear fractures is low. The nature is low. In Comparative Example 2, since the weight ratio of the sea component ratio (PET) is small and the weight ratio of the island component ratio (PEN) is large, the formation of the composite cross section is unstable, causing fineness spots, and the island component (PEN). Due to the occurrence of a single cross section, the delamination phenomenon was remarkable, the spinnability was poor, and the number of wrinkle wear fractures was significantly reduced. Since Comparative Example 3 is a simple seascore section with 1 island, the stress dispersion effect by the island component (PEN) is insufficient, and stress concentrates on the sea component (PET) that forms the fiber surface layer. The occurrence index is low, and soot wear fracture occurs in the initial number of tests. In Comparative Example 4, since the spinning speed was less than 5000 m / min, the strength, the elastic modulus, and the heat shrinkability, that is, the dimensional stability were insufficient, and the number of wrinkle breaks was low. In Comparative Example 5, the yarn once wound at a low spinning speed was stretched in two stages and subjected to heat treatment, but the orientation was insufficient because the stretchability was insufficient and the ratio of uniform stretching was relatively small. , Strength, elastic modulus and delamination generation index are low and wear resistance is poor.
[0045]
【The invention's effect】
In the present invention, polyethylene terephthalate polyester (S) is a sea component, polyethylene naphthalate polyester (I) is an island component, (I) is 40 to 90 wt%, (S) is 10 to 60 wt%, the number of island components Is produced by spinning a sea-island type composite fiber having a thickness of 4 or more at a speed of 5000 m / min or more, and is excellent in abrasion resistance, fibrillation resistance, dimensional stability, high elasticity, high strength, and spinnability. It is possible to provide ultra-fine monofilaments suitable for high-mesh screen dredging applications with stable operability and high production efficiency.
[Brief description of the drawings]
FIG. 1 is a schematic view of an apparatus used for measuring the number of wrinkle wear fractures.
[Explanation of symbols]
1 Monofilament 2 Weight for load 3 筬 4 Upper comb teeth 5 Lower comb teeth

Claims (3)

Polyester monofilaments spun at a speed of 5000 m / min or more, wherein the polyester monofilament is polyester (S) composed of 85% or more of polyethylene terephthalate component and polyester (I) composed of 85% or more of polyethylene naphthalate component. ) Is an island component, (S) is 10 to 60 wt%, (I) is 40 to 90 wt%, the number of the island components is 4 or more, and is a sea-island type composite fiber, and its fineness is 7.0 dtex or less. A polyester monofilament for screen cocoons characterized by being. The polyester monofilament for a screen wrinkle according to claim 1, having a strength of 4.4 cN / dtex or more, an elastic modulus of 130 cN / dtex or more, a 150 ° C dry heat shrinkage of 4% or less, and a delamination generation index of 10% or more. A screen cage made of the polyester monofilament according to claim 1 or 2.

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