JPS6411068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a polyester for fibers that has excellent spinning and drawing properties, and in particular can yield high-quality polyester fibers free from defects such as yarn breakage and fuzz. <Technical Background> Polyester, particularly polyethylene terephthalate, has many excellent properties and is therefore widely used in various applications, particularly in fibers and films. Such polyesters are usually produced by esterifying terephthalic acid and ethylene glycol, transesterifying dialkyl terephthalate and ethylene glycol, or reacting terephthalic acid and ethylene oxide to form glycol of terephthalic acid. ester and/or
Alternatively, it is produced by producing 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. The polyester thus obtained is generally put into practical use by extruding it in a molten state into a fiber or film through a spinning nozzle or slit, and then stretching it. Furthermore, a method of subjecting intermediately oriented yarn (POY) obtained by melt spinning polyester at a high speed of 2000 m/min or more 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, yarn breakage, and fuzz that occur as the spinning speed increases, and found that molecular orientation decreases as the spinning speed of polyester increases. Knowing that crystallization under such conditions is one of the causes of yarn breakage, fuzz, 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 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. <Objective of the Invention> The object of the present invention is to provide a polyester for fibers from which high-quality polyester fibers without defects such as yarn breakage and fuzz during polyester melt spinning and drawing can be obtained. Even in the spinning speed range of 3,000 m/min or more where POY can be obtained, and even in the spinning speed range of 5,000 m/min or more where polyester fibers with practically sufficient properties can be obtained by just the spinning process, defects such as yarn breakage and fluffing can occur. An object of the present invention is to provide a polyester for textiles from which high-quality polyester fibers can be obtained. <Structure of the Invention> As a result of intensive studies to achieve the above object, the present inventor has discovered that matte particles, which are inorganic particles contained in the largest amount in polyester, are superior to crystallization under molecular orientation of polyester. The present invention was achieved based on the knowledge that the particle size and particle size distribution of titanium dioxide, which is used as an agent, has a great effect on yarn breakage and single fiber breakage during spinning or drawing. That is, the present invention is a polyester composition for fibers, characterized in that 0.01 to 3% by weight of titanium dioxide, which satisfies the following properties at the same time, is blended with melt-spun polyester. 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 : Cumulative weight of settled particles is 25% of total particle weight
Particle size when it becomes D ₇₅ : Cumulative weight of settled particles is 75% of total particle weight
Particle size when the particle size becomes larger] Coarse particles with a particle size of 1.5 μm or more account for the total particle weight.
0.5% by weight or less The polyester referred to in the present invention is a glycol whose main acid component is terephthalic acid and at least one type of glycol, preferably at least one alkylene glycol selected from ethylene glycol, trimethylene glycol, and tetramethylene glycol. The main target is polyester as a component. It may also be a polyester in which a part of the terephthalic acid component is replaced with another difunctional carboxylic acid component, and/or a part of the glycol component is replaced with the above-mentioned glycol other than the main component or other diol component. It may also be made of polyester. Examples of difunctional carboxylic acids other than terephthalic acid used here include isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid,
Diphenoxyethanedicarboxylic acid, β-hydroxyethoxybenzoic acid, p-oxybenzoic acid, 5-
Examples include aromatic, aliphatic, and alicyclic difunctional carboxylic acids such as sodium sulfoisophthalic acid, adipic acid, sepacic acid, and 1,4-cyclohexanedicarboxylic acid. Examples of diol compounds other than the above-mentioned glycols include aliphatic, alicyclic, and aromatic diol compounds such as cyclohexane-1,4-dimethanol, neopentyl glycol, bisphenol A, and bisphenol S, and polyoxyalkylene glycols. can be given. Such polyesters may be synthesized by any method. For example, in the case of polyethylene terephthalate, usually terephthalic acid and ethylene glycol are directly esterified, a lower alkyl ester of terephthalic acid such as dimethyl terephthalate is transesterified with ethylene glycol, or terephthalic acid and ethylene glycol are transesterified. The first stage reaction is to react with terephthalic acid to produce a glycol ester and/or its low polymer, and the first stage reaction product is heated under reduced pressure until the desired degree of polymerization is achieved. It is produced by a second step of polycondensation reaction. Titanium dioxide, which is a matting agent used in the polyester composition for fibers of the present invention, has a small particle size and a sharp particle size distribution, with extremely 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 is necessary that the particles have a particle size distribution controlled to 2.2, particularly preferably 1.4 to 2.1, and that 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 diameter 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, polyester containing titanium dioxide as a matting agent whose average particle diameter, particle size distribution ratio [γ], or coarse particle amount is outside the range specified in the present invention, may be cut 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 needs to be 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 matting effect will be insufficient, while if it exceeds 3% by weight, the pressure within the spinning pack during spinning will increase significantly. The crystal form of titanium dioxide blended into the polyester for fibers of the present invention is preferably anatase type.
On the other hand, polyester for fibers using titanium dioxide, which has a rutile crystal form, tends to have a high occurrence of yarn breakage and single fiber breakage during spinning or drawing. 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. The polyester composition for fibers of the present invention can be obtained by adding titanium dioxide having the average particle size, particle size distribution ratio, and coarse particle amount specified in the present invention at any stage before the polycondensation reaction of polyester is completed. . As the titanium dioxide to be added at this time, it is not possible to use a commercially available product as is; 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, it is only possible to use products that have been treated in combination with treatments such as overtreatment. 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 diacid as defined in the present invention is obtained. Furthermore, the polyester composition for fibers of the present invention may contain titanium dioxide defined in the present invention in combination with the aforementioned aliphatic monocarboxylic acid metal salt and/or p-hydroxybenzoic acid or its ester-forming derivative. This is also preferable since crystallization of the polyester under molecular orientation 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 matting agent in polyester compositions for textiles, has traditionally had a broad particle size distribution even if the average particle size is small, and has a large amount of coarse particles. As a result, stress concentration due to the coarse particles occurred, resulting in frequent yarn breakage and single fiber breakage during spinning or drawing. In this regard, the polyester composition for fibers of the present invention has a small average particle diameter, a sharp particle size distribution, and an extremely small amount of coarse particles.As a result, stress concentration due to coarse particles is extremely small. When the polyester composition for fibers of the invention is spun at about 1000 m/min and then subjected to a normal drawing process, or when it is spun at about 3000 m/min, or even at a spinning speed of 5000 m/min or more. In either case, high-quality polyester fibers with very little yarn breakage, very little single fiber breakage, and very little fluff can be obtained. <Effects of the Invention> According to the polyester composition for fibers of the present invention, uniform, 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. <Examples> The present invention will be explained in detail below using examples. The spinning and drawing properties of the polyester in this example were evaluated using the following three types of spinning speeds. (a) Spinning speed 5500 m/min Polyester 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 yarn breaks during spinning and the number of fuzz of the obtained polyester fibers were investigated. 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 determined by counting the number of fluffs of polyester fibers using a phototube method and is expressed as the number of fluffs per 1,000,000 M. (b) Spinning speed 3000 m/min Polyester was melt-spun at 285° C. from a spinneret having 36 spinning nozzles each having a diameter of 0.3 mm at a discharge rate of 38 g/min and at a spinning speed of 3000 m/min. The yarn breakage occurrence rate is expressed as a percentage of yarn breakage per 100 dots of 2.5 kg of one dot. (c) Spinning speed 1200m/min Polyester at 285℃ using a spinning nozzle with a diameter of 0.3mm
Melt spinning was carried out at a spinning speed of 1200 m/min by discharging 80 g/min from a spinneret having 30 spinnerets. 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 on which single fibers were wrapped around the drawing roller was expressed as a wrap rate, expressed as a percentage per 100 drawing weights. Example 1 (Preparation of titanium dioxide slurry) 30 parts of titanium dioxide powder containing phosphorus element and potassium element in the amounts shown in Table 1 and ethylene glycol
A slurry (1) was prepared using a homogenizer. The average particle size of titanium dioxide constituting this slurry was 0.64 μm, and the particle size distribution ratio [γ] was 2.9. Next, the titanium dioxide ethylene glycol slurry was processed using a sand grinder to create a titanium dioxide slurry (2). When the particle size distribution of this slurry particles was measured, the average particle size was 0.45 μm.
The particle size distribution ratio [γ] was 3.0, and the amount of coarse particles with a particle size of 1.5 μm or more was 1.1 wt%. Next, the slurry (2) is processed by a decanter suction machine that rotates at high speed, and then passed through a filter (nominal opening
Ethylene glycol slurry
(3) was created. When measuring the particle size distribution of this slurry, the average particle size was 0.43μ, the particle size distribution ratio [γ] was 1.8,
The amount of coarse particles was 0.5wt%. (Manufacture of polyester) Add 0.025 mol% of manganese acetate based on dimethyl terephthalate to 100 parts of dimethyl terephthalate and 70 parts of ethylene glycol, and heat at 150 to 250°C.
The transesterification reaction was carried out while distilling off methanol. At that time, an ethylene glycol slurry of the titanium dioxide particles previously prepared was added in an amount of 0.3% by weight based on the polyester. After the transesterification reaction, 25 parts of trimethyl phosphate,
75 parts of ethylene glycol in a closed system for 5 hours, 150
A glycol solution of a phosphorus compound prepared by heating under reflux at °C was added in an amount of 0.030 mol % based on dimethyl terephthalate in terms of trimethyl phosphate.
After that, antimony trioxide was added as a polycondensation catalyst.
0.030 mol% was added, and then the obtained reaction product was transferred to a polycondensation reactor equipped with a stirrer and a glycol condenser, and the temperature was gradually raised from 230°C to 280°C, and the pressure was gradually reduced from normal pressure to reduced pressure. 1Torr
The polycondensation reaction was carried out under high vacuum as follows. The obtained polymer was discharged from a discharge port, cooled with water, and then cut to obtain polyethylene terephthalate pellets in which titanium dioxide particles were dispersed. (Evaluation of spinning) The polyester polymer thus obtained was evaluated for spinning and drawing properties at the three spinning speeds described above. The results are shown in Table 1. Examples 2 to 7 Tests were carried out in the same manner as in Example 1 under the conditions shown in Table 1, except that the particle size distribution of titanium dioxide and the amount added thereof were changed. As shown in Table 1, good polyester fibers with less yarn breakage and fluff were obtained. Comparative Examples 1 to 4 Using ordinary titanium dioxide containing the phosphorus element and potassium element shown in Table 1, the average particle size, particle size distribution ratio [γ], and amount of coarse particles of 1.5 μm or more were the values shown in Table 1. An ethylene glycol slurry of titanium dioxide was prepared. Using this slurry, a polyester polymer was prepared in the same manner as in Example 1, and yarn production was evaluated. The results are also shown in Table 1. Example 8 860 parts of terephthalic acid and 390 parts of ethylene glycol
A portion of the mixture was placed in a pressure-resistant autoclave, and an esterification reaction was carried out at 220 to 260° C. for 3 hours under a pressure of 3 kg/cmG with N ₂ while distilling off the generated water. Ethylene glycol slurry of titanium dioxide previously prepared (same slurry as in Example 1)
was added in an amount of 0.3% by weight per polyester. After about 180 parts of water was distilled off, 0.04 part of trimethyl phosphate (5 mmol% to terephthalic acid) was added as a stabilizer, and after 10 minutes, 0.45 part of antimony trioxide (30 mmol% to terephthalic acid) was added as a polycondensation catalyst. was added to complete the esterification reaction. Next, a polycondensation reaction was carried out in the same manner as in Example 1 to obtain polyethylene terephthalate pellets. The yarn spinning evaluation was carried out in the same manner as in Example 1, and the results are also shown in Table 1. 【table】

Claims (1)

[Claims] 1. Titanium dioxide that satisfies the following properties at the same time is 0.01% for melt-spun polyester.
A polyester composition for textiles, characterized in that it contains ~3% by weight. 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 : Cumulative weight of settled particles is 25% of total particle weight
Particle size when it becomes D ₇₅ : Cumulative weight of settled particles is 75% of total particle weight
Particle size when the particle size becomes larger] Coarse particles with a particle size of 1.5 μm or more account for the total particle weight.
0.5% by weight or less 2 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 Claim 1
The polyester composition for fibers described in .