JPH0433888B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical field> The present invention relates to a method for producing polyester fiber,
More specifically, the present invention relates to a method for producing polyester fiber in which polyester is melt-spun at a take-up speed of 2000 m/min or more. <Technical Background> Polyesters, particularly polyethylene terephthalate, have many excellent properties and are therefore widely used in various applications, particularly in large quantities for textile applications. Polyester for such fiber applications is usually produced by esterifying terephthalic acid and ethylene glycol, transesterifying dialkyl terephthalate and ethylene glycol, or reacting terephthalic acid and ethylene oxide to produce terephthalate. By producing a glycol ester of an acid and/or a low polymer thereof, then heating this product under reduced pressure to cause a polycondensation reaction until a predetermined degree of polymerization is reached, and adding titanium dioxide as a quenching agent. It is manufactured by The polyester thus obtained is put into practical use by extruding it into a fiber from a spinning nozzle in a molten state and then stretching it. We also use 2000 polyester
A method in which intermediately oriented yarn (POY) obtained by melt spinning at a high speed of m/min or higher is subjected to stretching and false twisting is also becoming widely used. Furthermore, recently, a method has been proposed in which polyester fibers having practically sufficient properties can be obtained only through the spinning process by melt spinning polyester at a high speed of 5000 m/min or more. However, increasing the spinning speed, especially 5000
On the other hand, if the speed is higher than m/min, single fiber breakage and yarn breakage will increase during spinning, so the obtained polyester fiber will have many defects such as fluff, and the passability of higher processing steps will be significantly deteriorated. do. This tendency becomes more pronounced as the spinning speed increases, as the denier of single fibers decreases, and as the number of filaments increases, and in fact, it is extremely difficult to spin at a speed of 6000 m/min or higher. In such high-speed spinning, spinning stability cannot be obtained only by changing the spinning conditions, and it is also required to improve the raw material polyester. Therefore, one of the inventors of the present invention investigated yarn quality defects such as single fiber breakage and yarn breakage that occur as a result of increasing the spinning speed, and found that the problems caused by molecular orientation that occur as the spinning speed of polyester increases. Knowing that crystallization is one of the causes of yarn breakage, single fiber breakage, etc., a method for suppressing crystallization under such molecular orientation was previously disclosed in Japanese Patent Application No. 116978/1983. and the specification of Japanese Patent Application No. 57-128970. The former method is a method in which an aliphatic monocarboxylic acid metal salt is added at a stage before the polycondensation reaction of polyester is completed, and the latter method is a method in which P-hydroxyl is added at any stage until the polyester production is completed. This is a method of adding benzoic acid or its ester-forming derivative to prevent yarn breakage and single fiber breakage during high-speed spinning. Although these methods can certainly prevent yarn breakage during high-speed spinning, the expected effects still cannot be obtained at high spinning speeds of 5000 m/min or higher. Regarding this point, the two inventors further investigated and found that the particle size and particle size distribution of titanium dioxide, which is blended in the largest amount as a dissipating agent in polyester, is more important than crystallization under molecular orientation of polyester. Knowing that titanium dioxide has a great effect on yarn breakage and fiber breakage during spinning or drawing, we previously proposed in Japanese Patent Application No. 58-219625 that titanium dioxide, which has a small average particle diameter and a sharp particle size distribution, It was proposed that it would be effective to subject the blended polyester to high-speed spinning. Indeed, in high-speed spinning using polyester containing such fine titanium dioxide, conventional titanium dioxide containing coarse particles, that is, titanium dioxide with a broad particle size distribution even if the average particle size is small, is blended. Compared to conventional polyester, yarn breakage and single fiber breakage occur during spinning or drawing, and the resulting polyester fibers have lower mechanical properties such as Young's modulus, so further improvements are desired. There is. <Object of the invention> The object of the invention is to eliminate the above-mentioned drawbacks and improve the take-up speed.
When drawing undrawn yarn obtained by spinning at speeds of 2000 m/min or higher, or during high-speed spinning at take-up speeds of 5000 m/min or higher, fibers with extremely low occurrence of yarn breakage and single fiber breakage, and excellent mechanical properties are produced. An object of the present invention is to provide a method for producing the resulting polyester fiber. <Structure> As a result of studies to achieve the above object, the present inventors have found that fine titanium dioxide is blended, and 2.
By subjecting polyester to which 6-naphthalene dicarboxylic acid has been added and copolymerized to high-speed spinning, yarn breakage and single fiber breakage during spinning are reduced, and the mechanical properties such as Young's modulus of the resulting fibers are also improved. They discovered this and arrived at the present invention. That is, in the present invention, when manufacturing a fiber by melt-spinning a polyester whose main acid component is a terephthalic acid component at a take-up speed of 2000 m/min or more, the following general formula [ Titanium dioxide, which is copolymerized with 0.1 to 20 mol% of the compound represented by ] and also satisfies the following properties, is added to polyester.
This is a method for producing polyester fiber characterized by using a polyester fiber containing 0.01 to 3% by weight. general formula [In the formula, R is a hydrogen atom, or has 1 or 2 carbon atoms
represents an alkyl group. ] Titanium dioxide Average particle size is 0.50 μm or less In the particle size distribution expressed by the cumulative weight of sedimented particles by centrifugal sedimentation, the particle size distribution ratio [γ] shown by the following formula is 2.3 or less [γ] = D ₂₅ /D ₇₅ [However, D ₂₅ : Particle diameter when the cumulative weight of settled particles becomes 25% of the total particle weight D ₇₅ : Particle diameter when the cumulative weight of settled particles becomes 75% of the total particle weight] Particles Coarse particles with a diameter of 1.5 μm or more account for the total particle weight.
0.5% by weight or less Polyester as used in the present invention mainly refers to polyethylene terephthalate whose main acid component is a terephthalic acid component, but a portion (usually 20 mol% or less) of the terephthalic acid component is added to other difunctional carboxylic acids. Even if the polyester is replaced with an acid component,
It may also be a polyester in which a portion of the ethylene glycol component (usually 20 mol% or less) is replaced with another diol component. Furthermore, the polyester may be copolymerized or mixed with various additives, such as dye-facilitating agents, flame retardants, antistatic agents, hydrophilic agents, colorants, etc., as necessary. Such polyesters are usually produced by esterifying terephthalic acid and ethylene glycol, by transesterifying a lower alkyl ester of terephthalic acid such as dimethyl terephthalate with ethylene glycol, or by reacting terephthalic acid with ethylene oxide. It is produced by producing a glycol ester of terephthalic acid and/or a low polymer thereof, and then heating this product under reduced pressure to cause a polycondensation reaction until a predetermined degree of polymerization is achieved. In the present invention, it is important to use a polyester to be subjected to high-speed spinning at a take-up speed of 2000 m/min or more, which is copolymerized with a compound represented by the following general formula [] and which is blended with fine titanium dioxide. It is. general formula [In the formula, R is hydrogen filament, or carbon number 1 or 2
represents an alkyl group. ] Here, as the compound represented by the general formula [], 1,2-naphthalene dicarboxylic acid, 1,3-
naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid,
1,6-naphthalene dicarboxylic acid, 1,7-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,
Examples include 6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, and/or dimethyl esters and diethyl esters of these compounds. Among these compounds, 2,6-naphthalene dicarboxylic acid, dimethyl 2,6-naphthalene dicarboxylate, which is a compound represented by the following general formula [],
Diethyl 2,6-naphthalene dicarboxylate is preferred. general formula [In the formula, R is hydrogen filament, or carbon number 1 or 2
represents an alkyl group. ] Such a bifunctional naphthalene dicarboxylic acid compound (hereinafter sometimes referred to as a naphthalene compound)
is at any stage in the polyester manufacturing process until the number average degree of polymerization of the polyester reaches 30 (preferably, substantially after the transesterification or esterification reaction is completed and for the polycondensation reaction). copolymerization is carried out by continuing the polycondensation reaction to a predetermined degree of polymerization while heating under reduced pressure. The amount of naphthalene compound added and copolymerized at this time is
It is 0.1 to 20 mol% based on the terephthalic acid component. Here, the amount of added copolymerization of naphthalene compound is
If it is less than 0.1 mol%, yarn breakage and single fiber breakage during spinning or drawing (hereinafter sometimes referred to as spinning) will be reduced, and mechanical properties such as Young's modulus of the resulting polyester fiber will be improved. Unable to achieve
On the other hand, if it exceeds 20 mol %, although the mechanical properties of the resulting polyester fibers are improved, yarn breakage and single fiber breakage during spinning cannot be reduced. Incidentally, the amount of copolymerization of the naphthalene compound can be determined from the difference in melting point between the polyester and the polyester obtained without adding the naphthalene compound. It is important that the polyester used in the present invention is copolymerized with a naphthalene compound as described above and also contains fine titanium dioxide. Such fine titanium dioxide has a small particle size, a sharp particle size distribution, and very few coarse particles. That is, such titanium dioxide has an average particle size of
0.50 μm or less, preferably 0.10 to 0.50 μm,
Particle size distribution ratio [γ] is 2.3 or less, preferably 1.4~
It has a particle size distribution controlled to 2.2, particularly preferably 1.4 to 2.1, and coarse particles with a particle size of 1.5 μm or more account for 0.5% by weight or less based on the total particle weight. However, the average particle diameter, particle size distribution ratio [γ], and amount of coarse particles were measured by the following method. (1) Average particle size of titanium dioxide Calculated based on a centrifugal sedimentation curve obtained using a centrifugal particle size analyzer (Model CP-50 manufactured by Shimadzu Corporation). That is, based on the centrifugal sedimentation curve, the particle size at which the sedimented particle weight corresponds to 50% by weight of the total particle weight is read from the cumulative weight particle size distribution curve that represents the particle size and the weight of the sedimented particles relative to the total particle weight. This value was defined as the average particle size. (2) Particle size distribution ratio of titanium dioxide [γ] Based on the cumulative weight particle size distribution curve of the settled particles obtained in the measurement of the average particle size of titanium dioxide, the cumulative weight of the settled particles is equivalent to 25% by weight of the total particle weight. The diameter (D ₂₅ ) and the particle diameter (D ₇₅ ) at which the cumulative weight of the settled particles corresponds to 75% by weight of the total particle weight are read and calculated using the following formula. [γ]=D ₂₅ /D ₇₅ The smaller the value of [γ], the sharper the particle size distribution of the titanium dioxide particles. (3) Amount of coarse particles Particle size when measuring the particle size distribution ratio [γ] of titanium dioxide
The ratio of particles with a size of 1.5μ or more to the total particles was calculated. Here, in a polyester containing titanium dioxide as an quenching agent whose average particle diameter, particle size distribution ratio [γ], or coarse particle amount is outside the range specified in the present invention, it is necessary to cut the polyester during spinning or stretching. The purpose of the present invention cannot be achieved due to frequent breakage of threads and single fibers. There is no need to specify the lower limit of the average particle size and particle size distribution ratio [γ], but since titanium dioxide with a smaller average particle size and particle size distribution ratio [γ] has a higher production cost, the average particle size and particle size distribution Ratio [γ]
It is preferable to keep them at about 0.10 μm and 1.4, respectively. The amount of titanium dioxide that satisfies the average particle diameter, particle size distribution ratio [γ], and amount of coarse particles is 0.01 to 3% by weight based on the polyester. Here, if the amount of titanium dioxide blended is less than 0.01% by weight, the quenching effect will be insufficient, while if it exceeds 3% by weight, the pressure inside the spinning pack will be extremely high during spinning, and furthermore, when the amount is more than 3% by weight, Yarn breakage and single fiber breakage occur frequently. The crystal form of titanium dioxide used in the present invention is preferably anatase type. On the other hand, if titanium dioxide, which has a rutile crystal form, is used, spinning
Alternatively, yarn breakage and single fiber breakage tend to occur frequently during stretching. In addition, generally the spinning speed is 3000 m/min or more, especially
At high speed spinning of 5000 m/min or more, damage to the spinneret, guides, etc. becomes more noticeable than at spinning speeds of about 1000 m/min. This is due to wear of titanium dioxide, and in order to reduce such wear, it is preferable to use titanium dioxide containing larger amounts of phosphorus and potassium elements than those contained in conventionally used titanium dioxide. As such titanium dioxide, 0.25 in terms of P ₂ O ₅
% by weight or more, preferably in the range of 0.25% to 1.0% by weight, more preferably 0.28% to 1.0% by weight
Contains elemental phosphorus in the range of % by weight and calculated as _K2O
0.1% by weight or more, preferably in the range of 0.1% to 0.30% by weight, more preferably 0.1% to 0.28% by weight
Preferably, it contains elemental potassium in the range of % by weight. Here, the content of phosphorus element in terms of P ₂ O ₅ is
If the content of potassium element is less than 0.25% by weight, or if the content of potassium element in terms of K ₂ O is less than 0.1% by weight, the color tone of the titanium dioxide tends to worsen, and furthermore, the color tone of the titanium dioxide in ethylene glycol tends to deteriorate. tends to be less stable. Such fine titanium dioxide cannot be used directly as a commercially available product; first, titanium dioxide powder is pulverized to remove aggregated particles in a solvent such as ethylene glycol, and then coarse particles are separated by sedimentation. However, a combination of overtreatment and further treatment can be used for the first time. To explain this process specifically, a slurry of titanium dioxide powder and ethylene glycol is passed through a homogenizer and a sand grinder, and then passed through a decanter classifier and a filter (openings of 1μ) that rotate at high speed. Titanium dioxide as defined in the present invention is obtained. Such titanium dioxide can be blended into polyester by adding it to the polyester in the form of a glycol slurry at any stage before the completion of the polycondensation reaction of the polyester. In the present invention, polyester in which a naphthalene compound is added and copolymerized in this manner and fine titanium dioxide is blended is subjected to melt spinning at a take-up speed of 2000 m/min or more. There is no need to use any special melt spinning conditions at this time, and normal melt spinning conditions can be used. Further, the polyester used in the present invention may be used even at a take-off speed of less than 2000 m/min, but the effect is not as remarkable as when the polyester is subjected to melt spinning at a take-off speed of 2000 m/min or more. In addition, the polyester used in the present invention may be used in combination with the aforementioned aliphatic monocarboxylic acid metal salt and/or p-hydroxybenzoic acid or its ester-forming derivative, which may affect the molecular orientation of the polyester. This is also preferable because crystallization at the bottom can be suppressed. <Function> Generally, in spinning or drawing in which a draft acts on the fiber, if there are coarse particles in the fiber, stress will concentrate at that location, eventually leading to fiber breakage. The higher the spinning speed, the higher the drawing ratio, or the smaller the single fiber denier, the greater the draft, and if there is stress concentration, the fibers will easily break. On the other hand, titanium dioxide, which is the most abundant degreasing agent in polyester for textiles, is
Conventionally, materials with a broad particle size distribution and a large amount of coarse particles were used even if the average particle size was small, which caused stress concentration due to the coarse particles, resulting in frequent yarn breakage and single fiber breakage during spinning or drawing. That's what I did. In this regard, the polyester for fibers used in the present invention uses titanium dioxide, which has a small average particle diameter and a sharp particle size distribution, and has an extremely small amount of coarse particles, so stress concentration due to coarse particles is extremely small. Furthermore, in the present invention, by adding and copolymerizing a naphthalene compound, a naphthalene compound is added into the polyester molecular chain.

Since the rigid structural unit represented by the formula is introduced, fibers made of such polyester have improved mechanical properties such as Young's modulus, and it is thought that the fibers do not break easily even under high draft conditions. As a result, in the present invention, when spinning at about 2000 m/min and then passing through a normal drawing process, or
When spinning at around 3000m/min, even 5000m/min.
In any case where the fibers are spun at a spinning speed of 1 minute or more, it is possible to obtain high-quality polyester fibers with very little yarn breakage or single fiber breakage, and with improved mechanical properties such as Young's modulus. <Effects of the Invention> According to the present invention, uniform and high quality polyester fibers can be easily obtained. Moreover, since uniform, high-quality polyester fibers can be obtained even during high-speed spinning, extremely efficient production can be achieved. <Example> Next, the present invention will be explained in further detail by giving examples. In the examples, parts are parts by weight, and [η] is the intrinsic viscosity determined from the value measured at 30°C in an orthochlorophenol solvent. The L value and b value, which represent the color tone of the polymer, are values measured using a Hunter type color difference meter, and the larger the L value, the more the whiteness is improved, and the larger the b value, the stronger the yellowish tinge. show. In addition, the melting point (mp) of polyester was determined using a differential scanning calorimeter (manufactured by Du Pont, type 990) under a nitrogen atmosphere, at a heating rate of 20°C/min, and by measuring the amount of sample.
Measured under the condition of 10 mg. Examples 1 to 5, Comparative Examples 1 to 3 970 parts of dimethyl terephthalate, 640 parts of ethylene glycol, and 0.31 part of manganese acetate as a transesterification catalyst (25 mmol% vs. dimethyl terephthalate)
was charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser, and heated from 140°C to 230°C to carry out a transesterification reaction while distilling methanol produced as a result of the reaction out of the system. Three hours after the start of the reaction, the internal temperature reached 230°C, and 3.20 parts of methanol was distilled out. Here, 0.22 parts of trimethyl phosphate (30 mmol% to dimethyl terephthalate) was added as a stabilizer, and after reacting for 10 minutes, 0.44 parts of antimony trioxide (30 mmol%) was added as a polymerization catalyst.
dimethyl terephthalate) and 2,6-naphthalene dicarboxylic acid in the amounts shown in Table 1, and titanium dioxide shown in Table 1 were added. Then, the obtained reaction product was transferred to a polycondensation reactor equipped with a stirrer and a glycol condenser,
While gradually increasing the temperature from 230℃ to 285℃,
A polycondensation reaction was carried out to obtain a polymer with [η] 0.64 while reducing the pressure to a high vacuum of Hg. Quality of the obtained polymer ([η], mp, Col−L, Col−
b) are also shown in Table 1. This polymer was spun at 285℃ using a 0.3mm diameter spinning nozzle.
The material was spun from a spinneret having 30 spinnerets at a discharge rate of 80 g/min, and melt-spun at a spinning speed of 2000 m/min. The obtained undrawn yarn was stretched at a stretching temperature of 85°C and a stretching ratio of
The yarn was drawn 3.5 times at a drawing speed of 1100 m/min to form a 2.5 kg winding of 150 denier/30 filament yarn. At this time, the number of spindles at which single fiber breakage occurred and the single fibers were wrapped around the drawing roller is also shown in Table 1 as a wrap rate, expressed as a percentage per 100 drawing weights. The strength and Young's modulus of this drawn yarn are also shown in Table 1. Next, the same polymer was discharged at 290°C from a spinneret with 24 spinning nozzles with a diameter of 0.3 mm at a discharge rate of 31 g/min, and approximately 2 tons of polyester was melt-spun at a spinning speed of 5500 m/min. The number of threads and the number of single fiber breaks (fuzz) of the obtained polyester fibers were examined. The number of yarn breaks during spinning is expressed as the number of yarn breaks per ton of polyester discharged. In addition, the number of fluffs is calculated by counting the number of fluffs of polyester fibers using a phototube method, and is expressed as the number of fluffs per million meters. The obtained results are also shown in Table 1.

[Table] Example 6-12, Comparative Example 4-8 Same as Example 1 except that the amounts of added titanium dioxide and 2,6-naphthalene dicarboxylic acid were changed as shown in Table 2. After synthesizing a polymer using
Output from a spinneret with 24 mm spinning nozzles
Approximately 2 tons of polyester was melt-spun at a spinning speed of 31 g/min as shown in Table 2, and the number of yarn breaks during spinning and the number of fuzz of the obtained polyester fibers were examined. The results are also shown in Table 2.

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Claims (1)

[Claims] 1. When producing fibers by melt spinning a polyester whose main acid component is a terephthalic acid component at a take-up speed of 2000 m/min or more, the following polyester (with respect to the acid component): It is recommended to use a material in which 0.1 to 20 mol% of the compound represented by the general formula [] is added and copolymerized, and 0.01 to 3% by weight of titanium dioxide, which satisfies the following properties at the same time, is blended with the polyester. Characteristic method for producing polyester fiber. general formula [In the formula, R is a hydrogen atom, or has 1 or 2 carbon atoms
represents an alkyl group. ] Titanium dioxide Average particle size is 0.50 μm or less In the particle size distribution expressed by the cumulative weight of sedimented particles by centrifugal sedimentation, the particle size distribution ratio [γ] shown by the following formula is 2.3 or less [γ] = D ₂₅ /D ₇₅ [However, D ₂₅ : Particle diameter when the cumulative weight of settled particles becomes 25% of the total particle weight D ₇₅ : Particle diameter when the cumulative weight of settled particles becomes 75% of the total particle weight] Particles Coarse particles with a diameter of 1.5 μm or more account for the total particle weight.
0.5% by weight or less 2. The method for producing polyester fibers according to claim 1, wherein the compound represented by the general formula [] is represented by the following general formula []. [In the formula, R is a hydrogen atom, or has 1 or 2 carbon atoms
represents an alkyl group. ] 3. Claim 1, wherein the titanium dioxide contains 0.25% by weight or more of phosphorus element in terms of P ₂ O ₅ and 0.1% by weight or more of potassium element in terms of K ₂ O.
The method for producing polyester fibers described in Section 1.