JP2016108709A - Flame-retardant polyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant polyester fiber good in fiber forming property in manufacturing a polyester fiber, having excellent flame retardancy in a low phosphorus concentration and excellent in strength and toughness than conventional articles.SOLUTION: The above described problem is solved by a polyester fiber manufactured by blending a phosphorus compound represented by the following formula (1) so that the content of a phosphorus atom is 1000 to 15000 ppm to the weight of the polyester fiber and having intrinsic viscosity of 0.5 to 1.3 dL/g and terminal carboxyl group amount of 10 to 45 eq/T.SELECTED DRAWING: None

Description

  The present invention relates to a flame retardant polyester fiber. More specifically, the present invention relates to a flame retardant polyester fiber having excellent flame retardancy while having a low phosphorus concentration, and having excellent strength, elongation and toughness as compared with the conventional one.

  Polyester is used for various purposes because of its useful functionality, and is used for clothing, materials, and medical use, for example. Among them, polyethylene terephthalate is excellent in terms of versatility and practicality and is preferably used, but it is desired to impart flame retardancy to various polyester molded articles from the viewpoint of fire prevention and the like. In particular, polyester fibers are widely used in clothing, bedding, curtains, carpets, and the like, but since they are insufficient in terms of flame retardancy, various efforts have been made to improve this point. Methods for copolymerization or blending, methods for kneading flame retardants during the manufacture of molded products, and methods for post-processing molded products from polyester to attach or soak the flame retardant to the surface or inside of the molded products are proposed. These methods are also used for fibers.

  Among the above methods, the method of imparting flame retardancy by post-processing has drawbacks that the texture becomes rough, or the flame retardant drops off due to washing and friction, resulting in a decrease in performance. Moreover, in the method of kneading the flame retardant, the flame retardant oozes out in the manufacturing process of the molded product, causing trouble. On the other hand, the method of copolymerizing the flame retardant during the production of the polymer can overcome the above-mentioned drawbacks. As a method for copolymerizing this flame retardant, many methods have been proposed so far. For example, it is disclosed that a phosphoric acid ester is copolymerized with a polyester as a phosphorus compound (for example, Patent Documents). 1), a polymerization reaction is required to obtain a copolyester having the desired physical properties, and when a phosphorus compound is blended to an amount that imparts the desired flame retardancy, the physical properties of the fiber are marked. descend.

Moreover, as a method of blending a phosphorus-based flame retardant, it is disclosed that flame retardancy is expressed by blending a specific organic phosphorus-containing compound with polyester fibers (see, for example, Patent Documents 2 to 4). ). Specifically, there is described an example in which polyethylene terephthalate and a specific organic phosphorus compound are mixed to obtain a fiber, which is used as a woven fabric, and its flame retardancy (for example, oxygen index) is slightly improved. The technology described in this publication teaches flame retardancy of polyethylene terephthalate fiber, and there is no description about the yarn physical properties.
Moreover, the example of the resin composition which a flame retardance expresses by using the flame retardant of (1) Formula is described (for example, refer patent document 5). However, a flame-retardant polyester fiber having a high toughness necessary for applications requiring high elongation is not proposed.

Japanese Patent Publication No.55-041610 Japanese Patent Laid-Open No. 52-012329 German Patent Application No. 2630693 British Patent Application No. 1515223 Japanese Patent No. 4653373

  The object of the present invention is to solve the above-mentioned conventional problems, obtain a flame-retardant polyester by melting and kneading a flame retardant into polyester, and has excellent flame retardancy at a low phosphorus concentration, and has higher strength than conventional products. Another object of the present invention is to provide a flame retardant polyester fiber having both high elongation and high toughness.

  As a result of intensive studies, the present inventors have found that a polyester fiber polyester obtained by melt-kneading a specific phosphorus compound so that the phosphorus atom content is 1000 to 1500 ppm is excellent in flame retardancy and yarn physical properties. As a result, the present invention has been completed.

That is, according to the present invention, the object of the invention is achieved by the following.
1. A polyester fiber in which a phosphorus compound represented by the following general formula (1) is blended so that the phosphorus atom content is 1000 to 15000 ppm with respect to the weight of the polyester fiber, and the intrinsic viscosity is 0.5 to A polyester fiber having 1.3 dL / g and a terminal carboxyl group content of 10 to 45 eq / T.

2. 2. The polyester fiber according to claim 1, wherein each physical property of the phosphorus compound represented by the following general formula (1) satisfies the following requirements.
(A) Organic purity is 97.0% or more and 100% or less (b) Chlorine content exceeds 0 ppm and 1000 ppm or less (c) pH fluctuation value (ΔpH) is 0 or more and 1.0 or less (d) Residual solvent amount is 0 ppm Over 1000ppm

3. Breaking tensile strength is 2.0 to 6.5 cN / dtex, breaking elongation is 20 to 80%, (breaking tensile strength) × (breaking elongation) The toughness represented by ^0.5 is 19 to 30 The polyester fiber according to any one of the preceding items, which is characterized.
4). A polyester composition having an intrinsic viscosity of 0.5 to 1.3 dL / g blended with a phosphorus compound represented by the following general formula (1) so that the phosphorus atom compound is 1000 to 15000 ppm is spun by a melt spinning method. The method for producing a polyester fiber according to any one of the preceding items, wherein the polyester fiber is drawn at a speed of 800 to 4000 m / min, and the total draw ratio after spinning is 2.5 to 6.0 times.
5. A fiber structure comprising the polyester fiber according to any one of the preceding items.
6). A fiber structure according to the preceding item, wherein the fiber structure is at least one structure selected from a yarn, a knitted fabric, a nonwoven fabric, a woven fabric, and a fiber structure.

  According to the present invention, the flame retardant has excellent flame retardancy while having a low phosphorus concentration by melting and kneading a phosphorus-based flame retardant, and excellent in yarn properties such as hue, strength, elongation, and toughness. Can be provided.

Hereinafter, the present invention will be described in detail.
(Polyester resin)
The polyester resin used in the production of the flame-retardant polyester fiber of the present invention is mainly a polyester obtained by using aromatic dicarboxylic acid or its ester-forming derivative, diol and its ester-forming derivative as main starting materials. It is. Specific examples of dicarboxylic acids or ester-forming derivatives thereof include phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, isophthalic acid, 4, 4-diphenyldicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid, anthracene Dicarboxylic acids such as dicarboxylic acid, phenanthrene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, cyclohexane dicarboxylic acid, decalin dicarboxylic acid, tricyclodecane dicarboxylic acid and the like Etc. can be mentioned ester forming derivatives. Examples of the ester-forming derivative include dimethyl ester, diethyl ester, dipropyl ester, dibutyl ester, dipentyl ester, dihexyl ester, diphenyl ester, and acid halide of dicarboxylic acid. One or more of these compounds may be used in combination, but it is preferable to use terephthalic acid or an ester-forming derivative thereof, and more preferably all of the polyesters from which terephthalic acid or an ester-forming derivative thereof can be obtained. From the viewpoint of heat resistance, it is preferable to use 80 mol% or more based on the dicarboxylic acid component.

Specific examples of the diol and its ester-forming derivatives include ethylene glycol, trimethylene glycol, 1,2-propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, cyclohexanedimethanol, decanediol, dodecanediol, Tricyclo [5.2.1.0 ^2,6 ] decanedimethanol, polyethylene glycol, polypropylene glycol, 1,4-bis (β-hydroxyethoxy) benzene, 2,2-bis (p-β-hydroxyethoxyphenyl) Examples thereof include propane, dihydroxy compounds of bis (p-β-hydroxyethoxyphenyl) sulfone, and the like.

  You may add compounds other than the conventionally well-known dicarboxylic acid component and a glycol component in the range which does not impair the structural requirement and objective of this invention. Examples of the third component to be added include aliphatic oxycarboxylic acids (such as ω-hydroxycaproic acid) and aromatic oxycarboxylic acids (such as p-hydroxybenzoic acid). Also, compounds having one or more ester-forming functional groups (alcohol, benzoic acid, etc. or glycerin, pentaerythritol, trimesic acid, trimellitic acid, etc.) are within the range where the polymer is substantially linear. Can be used.

  It is preferable that the intrinsic viscosity (IV) of the polyester fiber is 0.5 to 1.3 dL / g in order to ensure the tensile breaking strength and breaking elongation of the polyester fiber or from the viewpoint of the productivity of the polyester fiber. Polyester fibers having a strength of less than 0.5 dL / g are difficult to melt-spin, and polyester fibers having high toughness cannot be obtained because the physical properties of high strength and high elongation are not compatible. In addition, when it exceeds 1.3 dL / g, it is difficult to uniformly mix the phosphorus compound because the melt viscosity of the polyester is high when the phosphorus compound is melt-kneaded with the polyester. Various spinning methods such as the first may be undesirable because the spinnability is lowered.

The carboxyl end group amount (hereinafter referred to as CV amount) is 10 to 45 eq / T (equivalent / 10 ⁶ g), which suppresses the decrease in IV during spinning, and further, the yarn strength in higher processing such as a dyeing process. It is preferable from points, such as suppression of a fall, 11-40 eq / T is more preferable, More preferably, it is 12-39 eq / T, Especially more preferably, it is 15-38.5 eq / T.

  The polyester fiber preferably has a color L value (CoL-L) of 49.0 to 80.0 and a color b value (CoL-b) of 0 to 7.0. More preferably, CoL-L is 50.0-79.0, CoL-b is 2.0-6.5, and still more preferably CoL-L is 51.0-78.0, CoL-b is 2.5 to 6.0. When the color value is not within the above range, the hue of the finally obtained fiber or fiber structure may deteriorate.

  The content of phosphorus atoms used in the flame-retardant polyester fiber in the present invention is required to be 1000 to 15000 ppm with respect to the weight of the polyester fiber, and if it is less than 1000 ppm, the flame-retardant performance is poor and the flame retardant is melted. The effect of increasing elongation (high toughness) by kneading becomes poor. On the other hand, if it exceeds 15000 ppm, it is necessary to increase the mixing of the phosphorus compound containing phosphorus atoms. As a result, the IV of the polymer is lowered and spinning becomes difficult, and the tensile strength and toughness of the obtained fiber are reduced. May also be undesirable. Preferably it is 1,100-15000 ppm, More preferably, it is 1200-15000 ppm, More preferably, it is 1300-14900 ppm, Most preferably, it is 3500-8000 ppm.

(Organic phosphorus compounds)
As the phosphorus-based flame retardant used for the flame-retardant polyester fiber of the present invention, a phosphorus compound represented by the following general formula (1) is used.

  The phosphorus compound represented by the formula (1) exhibits a very excellent flame retardant effect on the polyester fiber. As far as the present inventors know, it is difficult to add a small amount of flame retardant or copolymerization in the conventional halogen-free flame retardant of the polyester fiber, and there are many problems in practical use. There was a point.

  However, according to the present invention, the phosphorus compound represented by the general formula (1) is surprisingly easily made flame retardant for the polyester fiber by itself using a small amount of the compound alone, and the inherent properties of the polyester fiber. (Strength, elongation, knot strength, boiling water shrinkage, etc.) are less likely to be impaired. However, in the present invention, in addition to the phosphorus compound represented by the formula (1), other phosphorus compounds, fluorine-containing resins or other additives are used to reduce the use ratio of the phosphorus compound, and the flame retardancy of the polyester fiber. It can of course be formulated for improvement, improvement of the physical properties of the polyester fibers, improvement of the chemical properties of the polyester fibers or other purposes. In the present invention, the phosphorus compound represented by the chemical structural formula of the above formula (1) needs to be blended so as to satisfy the above numerical range as the concentration of phosphorus atoms with respect to the weight of the polyester fiber. Indicates that the phosphorus compound is dispersed in the polyester to form a composition, and the phosphorus compound itself or a partially decomposed phosphorus compound is copolymerized with the polyester main chain. It does not include the state that is being done.

  Next, a method for synthesizing the phosphorus compound in the present invention will be described. Although the said phosphorus compound showed the typical manufacturing method below, the phosphorus compound mix | blended in the polyester fiber of this invention may be manufactured by methods other than the method demonstrated below. The phosphorus compound can be obtained, for example, by reacting pentaerythritol with phosphorus trichloride, treating the oxidized product with an alkali metal compound such as sodium methoxide, and then reacting with benzyl halide.

  It can also be obtained by reacting pentaerythritol with aralkylphosphonic acid dichloride, or reacting pentaerythritol with phosphorus trichloride and reacting benzyl alcohol with a compound obtained by reacting pentaerythritol with phosphorus trichloride, followed by Arbuzov transition at high temperature. . The latter reaction is disclosed, for example, in U.S. Pat. No. 3,141,032, JP-A-54-157156, and JP-A-53-39698.

  A specific method for synthesizing the phosphorus compound will be described below. This synthesis method is merely for the purpose of explanation, and the phosphorus compound used in the present invention is not limited to these synthesis methods, but also modifications and other syntheses. It may be synthesized by the method. A more specific synthesis method will be described in the preparation examples described later.

(Method for synthesizing phosphorus compound of general formula (1))
A reaction product obtained by reacting pentaerythritol with phosphorus trichloride and then oxidizing with tertiary butanol can be obtained by treating with sodium methoxide and reacting with benzyl bromide. Alternatively, it can be obtained by reacting pentaerythritol with phosphorus trichloride and heat-treating the resulting product and the reaction product of benzyl alcohol in the presence of a catalyst.

  The phosphorus compound has an organic purity measured by HPLC of preferably 97.0% to 100%, more preferably 98.0% to 99.99%, still more preferably 99.0% to 99.99%. 9% or less is used. By using the phosphorus compound having an organic purity within this range, it is possible to obtain a polyester fiber having both high flame retardancy and good physical properties. In particular, the organic purity affects the flame retardancy of the obtained polyester fiber, and when the organic purity is low, a high level of flame retardancy cannot be obtained. Further, the phosphorus compound having a low organic purity may exhibit deterioration in hue and physical properties, particularly in heat resistance, of the polyester fiber obtained due to the influence of impurities.

  Here, the measurement of the organic purity of the phosphorus compound by HPLC can be effectively performed by using the following method. As the column, Develosil ODS-7 300 mm × 4 mmφ manufactured by Nomura Chemical Co., Ltd. was used, and the column temperature was 40 ° C. As a solvent, a mixed solution of acetonitrile and water 6: 4 (volume ratio) was used, and 5 μl was injected. The detector used was UV-264 nm.

  As a method of removing impurities in the phosphorus compound and improving the organic purity, repulp washing with a solvent such as water, alcohol having 1 to 6 carbon atoms, or ketone compound having 1 to 6 carbon atoms (washing with a solvent, filtration) Represents the operation of repeating several times.) Is the most effective and cost effective. Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, isopropyl alcohol, normal propyl alcohol, butanol, pentyl alcohol, and hexyl alcohol. Examples of the ketone compound having 1 to 6 carbon atoms include acetone, Mention may be made of methyl ethyl ketone, diethyl ketone or ethyl propyl ketone. Among these compounds, water and ethanol which are easily available are more preferable. More effective cleaning is possible by stirring while heating the mixture of the phosphorus compound and the solvent during the cleaning. It is difficult to purify by ordinary recrystallization and distillation.

  The phosphorus compound preferably has a chlorine content exceeding 0 ppm and not more than 1000 ppm, more preferably not less than 1 ppm and not more than 500 ppm, and still more preferably not less than 10 ppm and not more than 100 ppm. One of the objects of the present invention is to provide a non-halogen flame retardant polyester fiber, and therefore it is preferable to use the phosphorus compound having a chlorine content within this range. Furthermore, by using the phosphorus compound having a chlorine content in this range, a polyester fiber having excellent thermal stability and a polyester fiber excellent in hue can be obtained. When the chlorine content exceeds this range, the thermal stability of the polyester fiber is lowered, and the hue may be lowered due to the occurrence of burns during high temperature molding. The chlorine content of the phosphorus compound can be effectively measured by analyzing by a combustion method and detecting by a titration method in accordance with ASTM D5808.

  The phosphorus compound preferably has a pH fluctuation value (ΔpH) of 0 or more and 1.0 or less, more preferably 0.001 or more and 0.8 or less, and further preferably 0.01 or more and 0.5 or less. And particularly preferably 0.05 to 0.3. Δ By using the phosphorus compound having a pH in this range, a polyester fiber having a good thermal stability and having a good hue can be obtained because the content of a trace amount of impurities whose pH fluctuates is small. Is obtained. When ΔpH exceeds this range, the thermal stability of the polyester fiber is lowered, and the hue may be lowered due to the occurrence of burns during high temperature molding.

The pH fluctuation value (ΔpH) of the phosphorus compound can be effectively measured by using the following method. That is, 99 g of distilled water and 1 g of a dispersant are mixed and stirred for 1 minute, and then the pH is measured with a pH meter (the obtained pH value is defined as pH 1). 1 g of the phosphorus compound is added to the mixed solution of the distilled water and the dispersing agent and stirred for 1 minute. The mixture after stirring is filtered, and the pH of the filtrate is measured with a pH meter (the obtained pH value is defined as pH 2). The ΔpH of the present invention can be calculated by the following formula (A).
ΔpH = | pH1-pH2 | (A)
That is, the pH fluctuation value (ΔpH) is the absolute value of the difference between the above pH1 and pH2.

  Further, the phosphorus compound preferably has a residual solvent amount exceeding 0 ppm and not more than 1000 ppm, more preferably not less than 1 ppm and not more than 800 ppm, more preferably not less than 5 ppm and not more than 500 ppm, particularly preferably not less than 10 ppm and not more than 100 ppm. Can be suitably used. By using the phosphorus compound having a residual solvent amount in this range, a polyester fiber having a high degree of flame retardancy can be obtained. Polyolefin resins generally have low flame retardancy, and when the phosphorus compound having a residual solvent amount exceeding this range is used, it becomes difficult to obtain desired flame retardancy. The residual solvent amount of the phosphorus compound can be effectively measured by the same method as the organic purity measurement method using HPLC.

  In order to bring the characteristics of the phosphorus compound such as organic purity, chlorine content, pH fluctuation value, and residual solvent amount into a predetermined numerical range, it is preferable to sufficiently purify at the final stage of the synthesis method described above. Specifically, in the manufacturing process other than the final stage, unreacted raw material compounds and side reaction products are sufficiently removed from the phosphorus compounds produced by purification means such as washing, filtration, recrystallization, and distillation. Can be preferably selected. More preferably, the above-described repulp washing method is employed. However, in the final purification process, it is important to employ the above-described repulp washing method.

  The said phosphorus compound is mix | blended in 0.1-20 weight part with respect to 100 weight part of polyester-type resin, Preferably it is 0.5-15 weight part, More preferably, it is 1-10 weight part. The preferred range of the blending ratio of the phosphorus compound is determined by the desired flame retardancy level, the type of polyester resin, and the like. Even if it is other than the polyester-based resin constituting the composition and the phosphorus-based compound, other components can be used as necessary as long as the object of the present invention is not impaired, and other flame retardants and flame retardant aids. The amount of the phosphorus compound can also be changed by using a fluorine-containing resin, and in many cases, the proportion of the phosphorus compound can be reduced by using these compounds.

  When the polyester fiber of the present invention is produced, the phosphorus compound represented by the above formula (1) is blended so as to be 1000 to 15000 ppm relative to the weight of the polyester composition, similarly to the polyester fiber degree. It is preferable to use a polyester composition.

  In producing the polyester fiber of the present invention, it is preferable to produce the polyester fiber in a manner similar to the method of performing melt spinning and then performing the stretching operation. For example, using a polyester composition in which the phosphorus compound is blended so that the phosphorus atom content is 1000 to 15000 ppm, after spinning, winding the undrawn yarn and drawing it separately, without winding up the undrawn yarn once A method of continuous drawing, a method of drawing after melt spinning, cooling and solidifying undrawn yarn in a coagulation bath, and then drawing in a heating medium or under contact heating with a heating roller, etc., or with a non-contact type heater, etc. Is done.

The spinning speed is taken up at a spinning speed of 800 to 4000 m / min. When the spinning speed is less than 800 m / min, an undrawn yarn having a relatively high degree of orientation cannot be obtained, and when the spinning speed exceeds 4000 m / min, orientation crystallization of the undrawn yarn is promoted and high strength is achieved. Not suitable for conversion.
Here, when drawing the melt-spun undrawn yarn, if the total draw ratio (total draw ratio) is set to be in the range of 2.5 to 6.0 times, the fiber finally obtained The tensile strength can be achieved at a high level, and the yarn breaking rate in the stretching process is low, which further improves productivity. The total draw ratio is more preferably in the range of 2.8 to 5.5 times, particularly preferably in the range of 3.0 to 5.0 times. The stretching step may be only one-step stretching or may be subjected to two or more stretching steps. For example, when adopting a two-step stretching method, the first-stage stretching ratio is 2.0 to 5.5 times, the second-stage stretching. The draw ratio may be about 1.0 to 2.0 times, and the total draw ratio may be adjusted to 2.5 to 6.0 times.

The polyester fiber of the present invention produced by such an operation has a breaking tensile strength of 2.0 to 6.5 cN / dtex, preferably 2.1 to 6.1 cN / dtex, more preferably 2.2 to 6.0 cN / dtex, more preferably 2.4 to 5.8 cN / dtex. The breaking elongation of the polyester fiber is 20 to 80%, preferably 22 to 75%, more preferably 24 to 73%, and still more preferably 25 to 70%. Further, the toughness calculated by (breaking tensile strength) × (breaking elongation) ^0.5 = (breaking tensile strength) √ (breaking elongation) is 19 to 30, preferably 19.5 to 29.7, more preferably. Is 20.0 to 29.5, more preferably 20.3 to 29.

  The polyester fiber thus obtained may be used as it is, or after it is subjected to bulk processing, or may be used for weaving or knitting, or may be used for weaving or knitting after being mixed or combined with other fibers. In addition, these polyester fibers may contain a small amount of other arbitrary polymers, antioxidants, antistatic agents, dyeing improvers, dyes, pigments, matting agents and other additives.

  The polyester fiber in the present invention can be used for various fiber structures containing the polyester fiber as it is or after being subjected to the above processing. As the fiber structure, any structure that can be taken by fibers, such as yarn, fiber, string, woven fabric, knitted fabric, nonwoven fabric, felt, papermaking, three-dimensional network, cotton, and sheet, can be preferably used. Among them, a fiber structure characterized by being at least one structure selected from the group consisting of yarn, knitted fabric, nonwoven fabric and woven fabric is preferable. These fiber casings can be arbitrarily selected from production methods generally known to those skilled in the art according to the purpose.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The evaluation was performed by the following method.

(1) Organic purity The column used Develosil ODS-7 300mmx4mmphi by Nomura Chemical Co., Ltd., and column temperature was 40 degreeC. As a solvent, a mixed solution of acetonitrile and water 6: 4 (volume ratio) was used, and 5 μl was injected. The detector used was UV-264 nm. From the measurement results, the organic purity was determined by the area ratio.

(2) Chlorine content Based on ASTM D5808, it analyzed by the combustion method and detected by the titration method.

(3) ΔpH
99 g of distilled water and 1 g of a dispersant (ethanol) are mixed, and after stirring for 1 minute, the pH is measured with a pH meter (the obtained pH value is “pH 1”). 1 g of the organophosphorus compound is added to the mixed solution of the distilled water and the dispersant and stirred for 1 minute. The mixture after stirring is filtered, and the pH of the filtrate is measured with a pH meter (the obtained pH value is “pH 2”). ΔpH was calculated by the following formula (A).
ΔpH = | pH1-pH2 | (A)

(4) Residual amount of solvent Develosil ODS-7 300 mm × 4 mmφ manufactured by Nomura Chemical Co., Ltd. was used as the column, and the column temperature was 40 ° C. As a solvent, a mixed solution of acetonitrile and water 6: 4 (volume ratio) was used, and 5 μl was injected. The detector used was UV-264 nm. The amount of residual solvent was calculated using a separately prepared calibration curve.

(5) Oxygen index (LOI evaluation)
This was performed in accordance with JIS-K-7201. The higher the value, the better the flame retardancy.

(6) Intrinsic viscosity Inherent viscosity number is determined by weighing a certain amount of chip, dissolving it in o-chlorophenol at a concentration of 0.012 g / ml, and then once cooling it, and the solution is 35 ° C. using an Ubbelohde viscometer. It calculated from the solution viscosity measured on the temperature conditions.

(7) Containing Phosphorus Concentration The phosphorous content was measured from a tubular knitted fabric by fluorescent X-rays (manufactured by Rigaku, Rataflex RU200) by a conventional method.

(8) Identification of chemical structure The primary structure of the polyester constituting the polyester fiber obtained according to the present invention is obtained by dissolving a polyester fiber sample in hexafluoroisopropanol and measuring ¹ H-NMR using JEOLA-600 manufactured by JEOL. And assigned from the obtained spectrum. In addition, the compounded phosphorus compound is obtained by dissolving the polyester fiber sample in a good solvent such as hexafluoroisopropanol, reprecipitating with a poor solvent such as dimethylformamide (DMF), and extracting the phosphorus compound from the solution components. Similarly, ¹ H-NMR was measured and assigned to the obtained spectrum to identify the chemical structure.

(9) Tensile strength, elongation, toughness The tensile strength at break and elongation (breaking elongation) were measured according to the method described in Japanese Industrial Standard, JIS L1013: 1999 8.5. Furthermore, toughness was calculated from the tensile strength at break and the elongation according to the following formula. Toughness can be an index that simply represents the energy of fracture strength of polyester fibers.
(Toughness) = (breaking tensile strength: cN / dtex) × √ (breaking elongation:%) = (breaking tensile strength) × (breaking elongation) ^0.5

(10) Terminal carboxysyl group amount (CV amount)
After the obtained polyester composition was dissolved in benzyl alcohol at 200 ° C. under a nitrogen atmosphere, the amount of terminal carboxyl groups (equivalent / 10 ⁶ g = eq / T) was determined by titration as the number of equivalents per 1 t of polyester weight. ) Was measured.

(11) Color (L value, b value)
A polymer chip was placed on a white standard plate for color difference adjustment, and L and b on the plate surface were measured using a Hunter type color difference meter (CR-200 type) manufactured by Minolta. L indicates lightness, and the larger the value, the higher the lightness, and b the higher the value, the greater the degree of yellow coloring.

[Preparation Example 1] Preparation of 2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane, 3,9-dibenzyl-3,9-dioxide (FR-1) Stirrer, thermometer In a reaction vessel having a condenser, 22.55 g (0.055 mol) of benzyl bromide and 19.01 g of 3,9-dibenzyloxy-2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane (0.11 mol) and 33.54 g (0.32 mol) of xylene were charged and dry nitrogen was allowed to flow while stirring at room temperature. Next, heating was started in an oil bath, and the mixture was heated and stirred at a reflux temperature (about 130 ° C.) for 4 hours. After heating, the mixture was allowed to cool to room temperature, 20 mL of xylene was added, and the mixture was further stirred for 30 minutes. The precipitated crystals were separated by filtration and washed twice with 40 mL of xylene. The obtained crude product and 50 mL of methanol were placed in a reaction vessel equipped with a condenser and a stirrer and refluxed for about 3 hours. After cooling to room temperature, the crystals were separated by filtration and washed twice with 20 mL of methanol, and the obtained filtrate was dried at 120 ° C. and 1.33 × 10 ² Pa for 20 hours to obtain white scaly crystals. It was. The product was confirmed to be bisbenzylpentaerythritol diphosphonate by mass spectral analysis, ¹ H, ³¹ P nuclear magnetic resonance spectral analysis and elemental analysis. The yield was 19.76 g, the yield was 88%, and the ³¹ P-NMR purity was 99%. The organic purity measured by the method described in the text was 99.5%. The chlorine content was 51 ppm. ΔpH was 0.1. The residual solvent amount was 47 ppm.

[Preparation Example 2] Preparation of 2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane, 3,9-dibenzyl-3,9-dioxide (FR-2) 2 in 40 ml of xylene It was prepared by the same preparation method as in Preparation Example 1, except that the operations of washing twice and methanol reflux washing were omitted.
The yield was 21.33 g, the yield was 95%, and the ³¹ P-NMR purity was 95%. The organic purity measured by the method described in the text was 94.0%. The chlorine content was 2500 ppm. ΔpH was 1.5. The amount of residual solvent was 1100 ppm.

[Examples 1, 2, 4, 6, 9 and Comparative Examples 2 and 3]
A polyester having the type and IV (inherent viscosity) listed in Table 1 and a phosphorus compound are blended in the amounts (parts by weight) shown in Table 1, and melt-kneaded at 230 ° C. with a vented twin screw extruder. A polyester composition having an intrinsic viscosity of (flame retardant polyester composition) was obtained. This polyester composition was spun from a die at an atmospheric temperature of 250 to 280 ° C. and taken up at a take-up speed of 1000 m / min. Subsequently, the film was drawn in one or two stages to obtain a filament of 80 to 85 dtex. Table 2 shows the physical properties of this filament yarn. A cylindrical knitting was produced using this filament yarn, and the LOI value was measured. The LOI was 24.5. The results are shown in Tables 1 and 2.

[Example 3]
A flame retardant polyester was obtained and fibers were obtained in the same manner as in Example 2 except that the spinning speed and the draw ratio were changed. The results are shown in Tables 1 and 2.

[Examples 5 and 7]
A flame retardant polyester was obtained in the same manner as in Example 2 except that an additional amount of the flame retardant auxiliary (benzotriazole) described in Table 1 was further added to obtain a fiber. The results are shown in Tables 1 and 2.

[Example 8]
A flame-retardant polyester was obtained and fibers were obtained in the same manner as in Example 2 except that 0.3 wt% of titanium oxide was added. The results are shown in Tables 1 and 2.

[Comparative Example 1]
A flame retardant polyester was obtained and fibers were obtained in the same manner as in Example 1 except that no phosphorus compound was blended. Each physical property is shown in Table 1. The results are shown in Tables 1 and 2.

[Comparative Example 4]
Phosphorus flame retardant M-Ester [6H-dibenz [c, e] [1,2] oxaphospholine--with terephthalic acid as the carboxylic acid component, ethylene glycol as the glycol component, and a phosphorus atom content of 6000 ppm. A compound represented by the following chemical structural formula (2) having a 6-oxide group] (purchased from Sanko Co., Ltd.) was copolymerized to obtain a flame-retardant polyester. This polyester was spun from the die at an atmospheric temperature of 250 to 280 ° C. and taken up at a take-up speed of 1000 m / min. Subsequently, the film was drawn in one or two stages to obtain a filament of 80 to 85 dtex. Table 2 shows the physical properties of this filament yarn. A cylindrical knitting was produced using this filament yarn, and the LOI value was measured. The LOI was 25.5. The results are shown in Tables 1 and 2.

[Example 10]
Various fiber structures were produced from the fibers obtained in the above-mentioned examples according to the following operations, and LOI evaluation was performed. The results are shown in Table 3.

(fabric)
The polyester fiber obtained in Example 2 was all distributed in warp and weft, and a plain fabric was obtained by a normal weaving method.
(knitting)
The polyester fiber obtained in Example 2 was used for a front heel, a middle heel, and a back heel, and a knitted fabric was obtained using a normal warp knitting machine.
(Nonwoven fabric)
The flame retardant polyester composition obtained in Example 2 was melt-spun at 250 to 280 ° C., and the long fibers taken up at a high speed by an ejector were continuously fed onto a moving net conveyor and conveyed, and embossed rollers. Thermocompression bonding (100 to 200 ° C.) was performed to obtain a long fiber nonwoven fabric.

  According to the present invention, it is possible to provide a flame-retardant polyester fiber having excellent flame retardancy while having a low phosphorus concentration by melting and kneading a phosphorus-based flame retardant, and having excellent yarn physical properties as compared with conventional ones.

Claims (6)

A polyester fiber in which a phosphorus compound represented by the following general formula (1) is blended so that the phosphorus atom content is 1000 to 15000 ppm with respect to the weight of the polyester fiber, and the intrinsic viscosity is 0.5 to A polyester fiber having 1.3 dL / g and a terminal carboxyl group content of 10 to 45 eq / T.

2. The polyester fiber according to claim 1, wherein each physical property of the phosphorus compound represented by the following general formula (1) satisfies the following requirements.
(A) Organic purity is 97.0% or more and 100% or less (b) Chlorine content exceeds 0 ppm and 1000 ppm or less (c) pH fluctuation value (ΔpH) is 0 or more and 1.0 or less (d) Residual solvent amount is 0 ppm Over 1000ppm

Breaking tensile strength is 2.0 to 6.5 cN / dtex, breaking elongation is 20 to 80%, (breaking tensile strength) × (breaking elongation) The toughness represented by ^0.5 is 19 to 30 The polyester fiber according to claim 1 or 2, characterized in that   A polyester composition having an intrinsic viscosity of 0.5 to 1.3 dL / g blended with a phosphorus compound represented by the following general formula (1) so that the phosphorus atom content is 1000 to 15000 ppm is obtained by a melt spinning method. The polyester fiber production according to any one of claims 1 to 3, wherein the spinning speed is 800 to 4000 m / min, and the total draw ratio after spinning is 2.5 to 6.0 times. Method.   The fiber structure containing the polyester fiber of any one of the said Claims 1-3.   The fiber structure is at least one structure selected from the group consisting of yarn, knitted fabric, nonwoven fabric and woven fabric.