JPS622073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing hollow fibers. More specifically, the present invention relates to a method for manufacturing hollow fibers made of polyester having special micropores and excellent water absorption and hygroscopicity. Polyester has many excellent properties and therefore has an extremely wide range of uses as a synthetic fiber. However, since polyester fibers are hydrophobic, their use in fields where water absorption and hygroscopicity are required is limited. Conventionally, as a method of imparting water absorbency and hygroscopicity to polyester fibers, a hydrophilic compound such as polyalkylene glycol or polyalkylene glycol and a metal sulfonic acid salt, a metal phosphate salt, or a phosphorous salt is added to the polyester fiber before forming it into a fiber. A method of blending with an acid metal salt or a phosphonate metal salt has been proposed. However, the fibers obtained by this method do not have sufficient water absorption and hygroscopicity, and their durability easily decreases due to washing, etc., and their physical properties such as light resistance and heat resistance also decrease. There is. In addition, the above polyalkylene glycol or polyalkylene glycol and sulfonic acid metal salt,
Polyester fibers obtained by blending metal phosphates, metal phosphites, or metal phosphonates are treated with an alkaline aqueous solution to form wrinkle-like micropores arranged in the fiber axis direction on the fiber surface to improve water absorption. , methods for improving hygroscopicity have also been proposed. However, the polyester fibers obtained by this method have a significant decrease in strength and cannot be used. The inventors of the present invention have made extensive studies to provide polyester fibers with excellent water absorption and hygroscopicity that do not have the above-mentioned drawbacks, and have developed a polyester blended with a sulfonic acid metal salt that has a lower viscosity than polyester at the melting temperature of polyester. By removing at least a portion of the sulfonic acid metal salt from the hollow fiber, the sulfonic acid metal salt is scattered over the entire cross section of the hollow fiber, arranged in the fiber axis direction, and at least a portion of which is hollow. I learned that it is possible to form micropores that communicate with the fibers, and by doing so, it is possible to obtain polyester fibers that have excellent water absorption, hygroscopicity, and durability, and are strong enough to withstand practical use. I suggested it earlier. However, the polyester fibers obtained in this manner may also show fibrillation due to abrasion during wear, and depending on the use, it is required to make the fibers even less likely to generate fibrils. The inventor of the present invention has conducted repeated studies in an effort to provide a polyester fiber that is sufficiently superior in water absorption, hygroscopicity, and durability, has a sufficiently low decrease in strength, and is difficult to fibrillate. It has been found that the above object can be achieved by melt-spinning hollow fibers using a modified polyester obtained by adding monomethyl disodium and treating the obtained hollow fibers with an aqueous alkaline solution. As a result of a detailed study of the structure of the hollow fibers obtained in this way, the hollow fibers obtained by mixing the hollow fibers obtained in this way and the low-viscosity metal sulfonate were treated with an aqueous alkaline solution. It was found that the shape of the micropores of each hollow fiber is completely different from that of the hollow fiber. That is, the micropores of the hollow fiber obtained by treating the hollow fiber mixed with the low-viscosity sulfonic acid metal salt with an alkaline aqueous solution have an extremely long shape with respect to its cross-sectional diameter. On the other hand, hollow fibers made from polyester containing the above-mentioned phosphorus compound, which is infusible at the melting temperature of polyester, and treated with an alkaline aqueous solution have extremely short micropores, and both are clearly different in the shape of their micropores,
It has been found that this difference greatly affects strength and fibril resistance. That is, most of the micropores of the hollow fiber obtained using the low-viscosity sulfonic acid metal salt have a diameter of 0.01 to 0.4 μm, and a length of more than 200 times the diameter. On the other hand, the micropores of hollow fibers obtained using the above-mentioned infusible phosphorus compound have a diameter in the range of 0.01 to 2 μm, and the length is no more than 20 times the diameter. , is clearly different from the hollow fiber using the low-viscosity sulfonic acid metal salt in the shape of its micropores. It has also been found that the effects, especially fiber strength and fibril resistance, vary greatly depending on the shape of the micropores. As a result of further studies based on this knowledge, the present inventor found that similar good results can be obtained even when using a phosphorus compound that is not only infusible at the polyester melting temperature but also has a higher viscosity than polyester. With this knowledge, the present invention has been completed. That is, the present invention synthesizes a polyester by reacting a difunctional carboxylic acid mainly consisting of terephthalic acid or its ester-forming derivative with a glycol mainly consisting of alkylene glycol having 2 to 6 carbon atoms or its ester-forming derivative. When melt-spinning the obtained polyester to form hollow fibers, the following general formula () can be used at any stage until the melt-spinning is completed. [Wherein, R is a monovalent organic group, X is -OH, -OR', -
OM ² or a monovalent organic group (R' is a monovalent organic group, M ² is a metal), M ¹ is a metal, and m is 0 or 1. ] At least one type of phosphorus compound represented by 0.3 to 15 mol % is added to the bifunctional carboxylic acid component, and the obtained hollow fiber is treated with an aqueous solution of an alkali compound to remove the phosphorus compound from the hollow fiber. By eluting 50% by weight of the hollow fiber, micropores are formed that are scattered in the cross section of the hollow fiber, arranged in the fiber axis direction, and at least a part of which communicates with the hollow part. It is a method of manufacturing fibers. The polyester used in the present invention has terephthalic acid as a main acid component, and is selected from alkylene glycols having 2 to 6 carbon atoms, such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, and hexamethylene glycol, particularly preferably ethylene glycol. The main target is polyester whose main glycol component is at least one type of glycol selected from , tetramethylene glycol. It may also be a polyester in which part of the terephthalic acid component is replaced with another difunctional carboxylic acid component, and/
Alternatively, it may be a polyester in which a part of the glycol component is replaced with a diol component other than the above-mentioned glycol. Examples of difunctional carboxylic acids other than terephthalic acid used here include isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid,
Examples include aromatic, aliphatic, and alicyclic difunctional carboxylic acids such as diphenoxyethanedicarboxylic acid, β-adipic acid, sebacic 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. can. 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. The following general formula () showing the phosphorus compound used in the present invention where M ¹ is a metal, especially an alkali metal,
Alkaline earth metal, Mn1/2, Co1/2, or Zn1/2
are preferred, especially Li, Na, K, Ca1/2, Mg
Particularly preferred is 1/2. m is 0 or 1. R is a monovalent organic group, specifically an alkyl group, an aryl group, an alkylaryl group, an arylalkyl group, or [(CH ₂ )lO]pR″ (where R″ is a hydrogen atom, an alkyl group, or a phenyl group). group, l is an integer of 2 or more, p is an integer of 1 or more), etc. are preferable. X is-
OH, -OR', ^-OM2 or a monovalent organic group,
R′ and R may be the same or different, M ² is the same as the definition of M ¹ above, M ² and M ¹ may be the same or different, and are monovalent organic groups. is the same as the definition of the organic group for R above, and may be the same as or different from R. Preferred specific examples of such phosphorus compounds include monomethyl disodium phosphate, dimethyl monosodium phosphate, monophenyl dipotassium phosphate,
Monomethyl monomagnesium phosphate, monomethyl manganese phosphate, polyoxyethylene (addition of 5 moles of EO), potassium lauryl ether phosphate (however, addition of 5 moles of EO means ethylene oxide 5
), polyoxyethylene (5 mole addition of EO) lauryl ether phosphate magnesium salt, polyoxyethylene (50 mole addition of EO) methyl ether phosphate sodium salt, monoethyl dipotassium phosphite , diphenyl monosodium phosphite, polyoxyethylene (50 moles of EO added) disodium methyl ether phosphite, monomethyl monosodium phenylphosphonate, monomethyl monopotassium nonylbenzenephosphonate, monomethyl monosodium phenylphosphinate, etc. I can do it. Even if the above phosphorus compound is used alone,
Moreover, two or more types may be used in combination. The timing of its addition is
It can be done at any stage before the end of the spinning process of melt spinning polyester into hollow fibers, for example, it can be added to the polyester raw materials, added during polyester synthesis, or melt spun after the end of synthesis. It may be added during this period. In any case, it is preferable to mix the components in a molten state after addition. If the amount of the above compound added is too small, the water absorbency and hygroscopicity of the hollow fibers finally obtained will be insufficient; on the other hand, if it is too large, the addition time will be insufficient before the synthesis of polyester is completed. It is difficult to obtain polyester with a certain degree of polymerization, and if it is added between after the completion of synthesis and before the completion of melt spinning, troubles are likely to occur during spinning. Therefore, the amount added should be in the range of 0.3 to 15 mol% based on the acid component constituting the polyester to be added, and 0.5
A range of 5 mol % is preferred. There is no need to employ any special method for melt-spinning the modified polyester to which the above-mentioned compound has been added to form hollow fibers, and any method for melt-spinning polyester hollow fibers may be employed. If the hollowness ratio of the hollow fiber obtained in this way is too low, the effect of improving water absorption and hygroscopicity by making it hollow will decrease, and if it is too high, the hollow part will be easily crushed, and once it is crushed, the water absorption and hygroscopicity will decrease. Therefore, the hollowness ratio, ie, the ratio of the cross section of the hollow portion to the apparent cross section of the fiber, is preferably in the range of 5 to 50%. Further, the outer shape and the hollow part shape in the cross section of the hollow fiber may have any shape. For example, when the outer shape and the hollow part are both circular, one of the outer shape and the hollow part is circular and the other is irregularly shaped. In this case, both the outer shape and the hollow portion may have similar or dissimilar shapes. Further, there is no need to particularly limit the size of the outer diameter. Furthermore, when spinning hollow fibers, a two-layer or more multilayer composite hollow fiber may be obtained by using a modified polyester to which the above compound is added and an unmodified polyester to which no compound is added. When spinning such a composite hollow fiber, it is necessary to arrange the modified polyester component to which the above compound is added so as to reach the hollow portion from the fiber surface. Part of the modified polyester can be easily removed from the hollow fibers thus obtained by subjecting them to stretching heat treatment or false twisting as necessary, or by immersing them in an aqueous solution of an alkaline compound after forming them into a fabric. can be done. The alkaline compounds used here include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, sodium carbonate,
Examples include potassium carbonate. Among these, sodium hydroxide and potassium hydroxide are particularly preferred. The concentration of such an aqueous solution of an alkali compound varies depending on the type of alkali compound, processing conditions, etc., but is usually preferably in the range of 0.01 to 40% by weight, particularly
A range of 0.1 to 30% by weight is preferred. The processing temperature is preferably in the range of room temperature to 100°C, and the processing time is 1 minute to 1 minute.
It is usually carried out for a period of 4 hours. In addition, the amount of modified polyester to be eluted and removed by treatment with this aqueous solution of an alkali compound is 2 to 2
It should be in the range of 50% by weight. By treating with an aqueous solution of an alkaline compound in this way, the hollow fibers are dispersed in the cross section of the fibers, arranged in the fiber axis direction, and at least a portion of which is connected to the hollow part, with a diameter of about 0.01 to 3 μm and a long length. Micropores are formed that are less than 50 times the diameter, and exhibit excellent water absorption and hygroscopicity. Note that the hollow fibers obtained by the method of the present invention may contain optional additives, such as catalysts, color inhibitors, heat resistant agents, flame retardants, fluorescent whitening agents, matting agents, colorants, and inorganic Fine particles etc. may be included. Further explanation will be given below with reference to Examples. In the examples, parts indicate parts by weight, and the water absorption, hygroscopicity, strength reduction rate after alkali treatment, and fibrillation resistance of the obtained hollow fibers were measured by the following methods. (i) Water absorption rate test method (according to JIS-L1018) The fibers are made into cloth, and the cloth is washed with a 0.3% aqueous solution of anionic detergent Zab (manufactured by Kao Soap Co., Ltd.) at 40℃ for 30 minutes in a household electric washing machine. Repeat the washing a specified number of times, then dry the sample, hang it horizontally, drop 1 drop of water (0.04 cc) from a height of 1 cm above the sample, and make sure that the water is completely absorbed by the sample and reflected light is observed. Measure the time until it disappears. (ii) Water absorption measurement method A sample obtained by drying a fabric is immersed in water for at least 30 minutes, and then dehydrated for 5 minutes in a dehydrator of a household electric washing machine. It was calculated from the weight of the dry sample and the weight of the sample after dehydration using the following formula. Water absorption rate = (sample weight after dehydration - dry sample weight) / dry sample weight (%) (iii) Strength reduction rate due to alkali treatment The strength of the fiber obtained by unraveling the fabric before alkali treatment and after alkali treatment The strength of the fibers obtained by unraveling the fabrics was compared. (iv) Fibril resistance Using a Gakushin type flat abrasion machine for friction fastness testing, using a dioset made of 100% polyethylene terephthalate as the friction cloth, the test cloth was abraded a specified number of times under a load of 500 g. The presence or absence of fibrillation was investigated. Example 1 197 parts of dimethyl terephthalate, 124 parts of ethylene glycol, and 0.118 parts of calcium acetate monohydrate were placed in a glass flask equipped with a rectification column, and a transesterification reaction was carried out according to a conventional method, until a theoretical amount of methanol was distilled out. After that, the reaction product was placed in a polycondensation flask equipped with a rectification column, and 0.112 parts of trimethyl phosphate was added as a stabilizer and 0.079 parts of antimony trioxide was added as a polycondensation catalyst.
1 part, 1.1 parts of monomethyl disodium phosphate (0.7 mol% based on dimethyl terephthalate),
The reaction was carried out at a temperature of 280° C. for 20 minutes under normal pressure and 15 minutes under reduced pressure of 30 mmHg, and then for 80 minutes under high vacuum. The final internal pressure was 0.35 mmHg, the intrinsic viscosity of the obtained modified polymer was 0.636, and the softening point was 260°C. After the reaction was completed, the modified polymer was made into chips according to a conventional method. The chips are dried in a conventional manner and placed in a spinneret.
Using a circular slit with a circular slit of 0.05 mm and a diameter of 0.6 mm, which had a spinning hole with an arc-shaped opening closed at two places, the yarn was spun according to a conventional method, and the ratio of the outer diameter to the inner diameter was 2. :1 hollow fiber (hollowness ratio 25%) was made.
This raw yarn was 300 denier/24 filaments, and was drawn in a conventional manner at a draw ratio of 4.2 times to obtain a multifilament of 71 denier/24 filaments. This multifilament is knitted into stockinette fabric, and after scouring and drying by the usual method,
Alkali weight loss rate: 20% by treatment with a caustic soda aqueous solution with the concentration listed in Table 1 at boiling temperature for the time listed in the table.
fabric was obtained. The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of this fabric were as shown in Table 1. Furthermore, no fibrillation was observed in microscopic observation after 200 wears. Example 2 0.95 parts of monomethyl monomagnesium phosphate (based on dimethyl terephthalate) was used in place of the monomethyl disodium phosphate used in Example 1.
A modified polymer having an intrinsic viscosity of 0.622 and a softening point of 257° C. was obtained in the same manner as in Example 1, except that 0.7 mol %) was used, and the rest was carried out in the same manner as in Example 1. The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of the fabric obtained are shown in Table 1, and no fibrils were observed when the fabric was observed under a microscope after being abraded 200 times. Example 3 Intrinsic viscosity 0.584, softening was carried out in the same manner as in Example 1 except that 2 parts of polyoxyethylene (added with 5 moles of EO) lauryl ether phosphate potassium salt was used in place of the monomethyl disodium phosphate used in Example 1. Obtain a modified polymer with a temperature of 260℃,
The rest was carried out in the same manner as in Example 1. The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of the fabric obtained are as shown in Table 1, and no fibrils were observed after the fabric was abraded 200 times. Example 4 Intrinsic viscosity 0.636, softening was carried out in the same manner as in Example 1 except that 2 parts of polyoxyethylene (5 moles of EO added) lauryl ether phosphate magnesium salt was used in place of the monomethyl disodium phosphate used in Example 1. A modified polymer having a temperature of 257°C was obtained, and the rest was carried out in the same manner as in Example 1. The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of the fabric obtained are as shown in Table 1, and no fibrils were observed after the fabric was abraded 200 times. Examples 5 and 6 Same as Example 1 except that 4 parts of monoethyl monosodium phenylphosphonate or 2 parts of diphenyl monosodium phosphite were used in place of monomethyl disodium phosphate used in Example 1. I went to The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of each of the fabrics obtained are shown in Table 1.
Microscopic observation after 200 times revealed no fibrils. Comparative Example 1 197 parts of dimethyl terephthalate, 124 parts of ethylene glycol, 1.2 parts of methyl o-benzoylbenzoate (gelling inhibitor), calcium acetate monohydrate
0.118 parts was placed in a glass flask equipped with a rectification tower, and transesterification was carried out according to a conventional method. After the theoretical amount of methanol was distilled out, the reaction product was placed in a polycondensation flask equipped with a rectification tower, and phosphoric acid was added. Add 1.42 parts of trimethyl (1 mol % based on dimethyl terephthalate) and 0.079 parts of antimony trioxide as a polycondensation catalyst, and heat at 280°C for 20 minutes under normal pressure, and under reduced pressure of 30 mmHg for 15 minutes.
After reacting for 80 minutes under high vacuum.
The final internal pressure was 0.38 mmHg, the intrinsic viscosity of the obtained modified polymer was 0.540, and the softening point was 255°C. After the reaction was completed, the modified polymer was made into chips according to a conventional method, and the same procedure as in Example 1 was carried out using these chips. The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of the obtained fabric were as shown in Table 1. Comparative Example 2 Example except that 4 parts of sodium phosphate (Na ₃ PO ₄ 12H ₂ O) (1.03 mol % based on dimethyl terephthalate) was used in place of monomethyl disodium phosphate used in Example 1. 1
A chip with an intrinsic viscosity of 0.653 was obtained in the same manner as above. This chip contained coarse insoluble sodium phosphate crystals of 5 μm or more, and when this chip was spun in the same manner as in Example 1, the spinning pressure suddenly increased and spinning was impossible. Comparative Example 3 197 parts of dithymer terephthalate, 124 parts of ethylene glycol, and 0.118 parts of calcium acetate monohydrate were placed in a glass flask equipped with a rectification column, and a transesterification reaction was carried out according to a conventional method, and a theoretical amount of methanol was distilled out. After that, the reaction product was placed in a polycondensation flask equipped with a rectification column, 0.112 parts of trimethyl phosphate and 0.079 parts of antimony trioxide were added, and the reaction proceeded at a temperature of 280°C for 20 minutes under normal pressure and 15 minutes under reduced pressure of 30 mmHg. After that, the pressure was returned to normal pressure, and after adding 50 parts of a mixture of sodium alkyl sulfonates having 8 to 20 carbon atoms and an average carbon number of 14, the pressure inside the system was gradually reduced, and the pressure was reduced to 80% while stirring.
Allowed to react for minutes. The final internal pressure is 0.32mmHg,
The intrinsic viscosity of the obtained polymer was 0.622.
After the reaction was completed, chips were formed according to a conventional method. Using this chip, spinning was carried out in the same manner as in Example 7.
The water absorption rate, water absorption rate, and strength reduction rate due to alkali treatment of the fabric obtained are shown in Table 2, and the generation of fibrils was observed by microscopic observation after the fabric was abraded 200 times. 【table】

Claims (1)

[Scope of Claims] 1 A polyester is synthesized by reacting a bifunctional carboxylic acid, mainly terephthalic acid, or an ester-forming derivative thereof with an alkylene glycol having 2 to 6 carbon atoms or an ester-forming derivative thereof. When melt-spinning the obtained polyester into hollow fibers, the following general formula () can be used at any stage until the melt-spinning is completed. [Wherein, R is a monovalent organic group, X is -OH, -OR', -
OM ² or a monovalent organic group (R' is a monovalent organic group, M ² is a metal), M ¹ is a metal, and m is 0 or 1. ] At least one type of phosphorus compound represented by 0.3 to 15 mol % is added to the bifunctional carboxylic acid component, and then the obtained hollow fiber is treated with an aqueous solution of an alkali compound to remove the phosphorus compound from the hollow fiber. By eluting ~50% by weight, micropores are formed that are scattered in the cross section of the hollow fiber, arranged in the fiber axis direction, and at least a part of which communicates with the hollow part. Hollow fiber manufacturing method.