JPH0551442A - Flame retardant copolyester - Google Patents

Abstract

PURPOSE:To obtain the subject nonpollution copolymer, excellent in processability, whiteness and resistance to light and washing while maintaining dynamic and thermal characteristics essential to a polyester by adding a specific amount of a specified phosphorus-containing bishydroxy compound and carrying out copolymerization. CONSTITUTION:The objective copolymer is obtained by copolymerizing one or more phosphorus-containing bishydroxy compounds expressed by the formula [R is 1-9C alkyl, aryl, aralkyl or cycloalkyl; R1 is 2-4C alkylene; A is bifunctional aromatic organic residue (without containing a halogen); m is 1 or 2; n is 1, 2 or 3] so as to provide 2000-30000ppm content of P in the resultant polyester. Furthermore, a polyester composed of a bifunctional carboxylic acid component consisting essentially of terephthalic acid (or its ester-forming derivative), etc., and a glycol component consisting essentially of ethylene glycol (or its ester-forming derivative), etc., is preferred as the polyester.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flame-retardant synthetic linear polyester copolymer modified with a phosphorus-containing bishydroxy compound. More specifically, the present invention relates to a flame-retardant polyester copolymer which is characterized in that a phosphorus-containing bishydroxy compound is added and copolymerized in the production of a polyester containing polyethylene terephthalate or polybutylene terephthalate as a main component.

Aromatic polyesters typified by polyethylene terephthalate have excellent mechanical properties, and are widely used as fibers, films, and other plastic molded products, and are extremely useful materials. At the same time, however, it has a drawback that it is easy to burn, and with the recent increase in awareness of fire, there is a strong demand for flame retardancy. In particular, the generation of toxic gases (cyan, halogen) at the time of combustion is regarded as a problem, and therefore the development of flame-retardant products that do not generate toxic gas is now under much demand.

[0003]

2. Description of the Related Art Various attempts have been made so far to make polyester flame-retardant. For example, a method of post-treating a flame-retardant agent on a molded article such as a fiber or a film, and a method of kneading the flame-retardant agent at the time of molding are known. However, the post-treatment method has various drawbacks such as complicated and non-uniform treatment, rough texture of the molded product, and reduced flame retardancy due to washing and the like. In the kneading method, the flame retardant is sublimated or colored during molding, or the mechanical properties of the molded product are remarkably deteriorated. Further, the flame retardant is used when the molded product such as a fiber product is dry cleaned. Has many drawbacks such as dropout and bleeding out, resulting in poor performance and hygiene problems due to contamination.

A so-called copolymerization method in which a phosphorus atom, which is one of the atoms imparting flame retardancy, is introduced into the main chain of the polyester molecule is effective as a method for improving such drawbacks, and various studies have been made in recent years. There are many suggestions. For example, JP-B-36-21050 and JP-B-38-9447 disclose methods of adding phosphonic acid or phosphonic acid esters. However, these proposed phosphonates generally have a low boiling point or cause a side reaction during the production of the basic aromatic polyester to be distilled out of the system, or the molding processability due to three-dimensionalization is difficult. It has the drawback of being impossible. Further, JP-B-36-20771 discloses a method of adding and copolymerizing a bifunctional, relatively high-boiling point phenylphosphonic acid bisglycol ester. However, it has a drawback that it is often distilled out of the system during the polymerization despite the high boiling point. Although the cause of this distillation to the outside of the system is not clear, it is presumed that self-condensation probably takes precedence and volatilizes as a cyclic low boiling point component.

In order to improve such drawbacks, for example, Japanese Patent Publication No. 47-13386 and Japanese Patent Laid-Open No. 50-39389 are added and copolymerized with a polymer of phosphonic acid, or phosphates having a trifunctional group are added together. A method of polymerizing is disclosed. Since such a method is a polymer and has a high boiling point, it is possible to considerably reduce the distillation outside the system, but when the degree of polymerization is large, the reactivity of the terminal functional group becomes poor and it is difficult to introduce it into the polyester main chain, and the mechanical properties of the polyester It has a drawback that it deteriorates, elution of unreacted substances occurs, and troubles such as gelation due to trifunctional groups occur. On the other hand, if the degree of polymerization is low enough not to reduce the reactivity, side reactions occur as described above and scatter out of the system, or the thermal stability is insufficient, resulting in a marked decrease in the whiteness and mechanical properties of the polyester. However, it has a drawback that it cannot be put to practical use. The publication also describes an example in which a divalent aromatic group having good thermal stability is used, but since the terminal functional group is a phenolic hydroxyl group, the ester forming property is poor and the degree of polymerization is sufficient. It has the drawback that

In JP-A-53-68756, phenylphosphonic acid and a polymerization catalyst are added after the transesterification reaction,
A method is disclosed in which the esterification reaction is allowed to proceed under mild conditions and then the polymerization is carried out. However, under mild conditions that suppress the formation of low boiling cyclic compounds, the esterification does not proceed, and under the conditions that allow the esterification to proceed sufficiently, the phosphorus compound will distill out of the system and a satisfactory result will not be obtained. The current situation is that a practical product has not yet been obtained.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to remedy the drawbacks of the prior art and to find a flame-retardant copolymerization component which is effective in a small amount and is non-polluting.

A first object of the present invention is to form a fiber or a film without deteriorating the original mechanical properties and thermal properties of polyester, which is excellent in whiteness, light resistance and washing resistance. To provide a water-soluble polyester copolymer. A second object of the present invention is to provide a useful flame-retardant polyester in which the flame-retardant copolymer component does not volatilize or decompose or scatter out of the system during polymerization or molding of the polyester and does not inhibit polymerization and has excellent heat resistance. To provide a copolymer. A third object of the present invention is to provide a flame-retardant polyester copolymer which does not generate a harmful gas to the human body during flame contact, is extremely excellent in self-extinguishing property, and can be easily and inexpensively produced industrially. is there.

[0009]

Means for Solving the Problems As a result of various investigations and intensive studies on the flame-retardant copolymerization component, the present inventors have found that aromatic dicarboxylic acid is reacted in advance with, for example, an epoxy compound or glycol. To find that the phosphonic acid compound derived from the alcoholic hydroxyl group blocked with an ester bond is extremely excellent in thermal stability, has no formation of a low boiling point substance, and can easily obtain a copolyester, and complete the present invention. I arrived. In particular, despite having a structure similar to phosphonic acid bis-ethylene glycol ester that is easily cyclized in terms of chemical structure, the hydroxyl group at one end is previously reacted with a carboxylic acid group to block it with an ester bond. It is surprising that it is stabilized by increasing the molecular weight, is stable even under severe conditions during the polycondensation reaction of polyester, and does not distill out of the system at all.

That is, the present invention has the general formula (I)

[Chemical 2] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, an allyl group, an aralkyl group, and a cycloalkyl group, R ₁ is an alkylene group having 2 to 4 carbon atoms, and A is a divalent aromatic organic residue ( (Not containing halogen), m is 1 to 2, and n is an integer of 1 to 3), and the phosphorus atom content in the polyester is 2,000 to 30, It is achieved by a flame-retardant polyester copolymer characterized by being copolymerized to 000 ppm.

The dicarboxylic acid component used in the polyester copolymer of the present invention includes terephthalic acid, isophthalic acid, 2.6-naphthalenedicarboxylic acid, 1.5-naphthalenedicarboxylic acid, 4.4-diphenyldicarboxylic acid,
Bis- (4-carboxyphenyl) ether, bis-
(4-carboxyphenyl) sulfone, 1.2-bis (4-carboxyphenoxy) ethane, 5-naphthosulfosulfoisophthalic acid, 5-sulfopropoxyisophthalic acid, diphenyl p. p'-dicarboxylic acid, p-phenylenediacetic acid, diphenyl oxide-p. P'-dicarboxylic acid, trans-hetisahydroterephthalic acid, and ester-forming derivatives thereof such as alkyl ester, aryl ester, and ethylene glycol ester are included. Especially useful are terephthalic acid,
2.6-Naphthalenedicarboxylic acid as a main component and, if necessary, other aromatic dicarboxylic acids and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decamethylenedicarboxylic acid, and ester-forming derivatives thereof It is possible to mix and use a small amount of at least 10 mol% of the above species.

On the other hand, as the glycol component, ethylene glycol, 1.2-propylene glycol, 1.4-butanediol, trimethylene glycol, 1.6-hexanediol, 1.4-cyclohexanediol, neopentyl glycol, 1. 4-cyclohexanedimethanol, bisphenol A, bisphenol S, diethylene glycol, polyethylene glycol, polypropylene glycol and the like can be mentioned. Among them, ethylene glycol and 1.4-butanediol, which are useful, may be used as a main component, and one or more other glycol components and ester-forming derivatives may be mixed in a small amount up to 10 mol% of the diol component. it can.

Further, as the oxycarboxylic acid component, 4-
Examples thereof include oxybenzoic acid, 4-hydroxyethoxybenzoic acid and oxypivalic acid, and these can be added in small amounts if necessary.

If the polyester copolymer of the present invention is a substantially linear polymer, optionally a small amount of a monofunctional compound such as benzoic acid, benzoylbenzoic acid, acetic acid, methoxypolyethylene glycol, or the like, or It is also possible to add trifunctional or higher functional compounds such as glycerin, pentaerythritol, trimellitic acid, pyromellitic acid, phosphoric acid compounds and ester-forming derivatives thereof.

The polyester copolymer of the present invention comprises, for example, an aromatic dicarboxylic acid component containing terephthalic acid or 2.6-naphthalenedicarboxylic acid as a main component and a glycol component containing ethylene glycol or 1.4-butanediol as a main component. In addition, when producing an aromatic polyester containing 4-oxybenzoic acid as a main component, the phosphorus-containing bishydroxy compound represented by the general formula (I) is added and copolymerized.

As a method for producing such a copolymer, a conventionally known method can be applied. In that case, the time of addition can be selected and added as necessary, such as in the transesterification reaction step, before polycondensation, during polycondensation, or shortly before completion of polycondensation. However, although the present invention is not restricted by such addition timing, since the phosphorus-containing bishydroxy compound already has a glycol ester structure, it is preferable to add it in the step after completion of the transesterification reaction. As a matter of course, a known catalyst can be used for the transesterification reaction and the polycondensation reaction.

Pigments, matting agents, optical brighteners, heat stabilizers,
Various kinds of ultraviolet absorbers, antioxidants, antistatic agents, and ether bond inhibitors such as organic amines and organic carboxylic acid amides may be used if necessary.

The amount of the phosphorus-containing bishydroxy compound represented by the general formula (I) is such that the phosphorus atom content in the obtained polyester is 2,000 to 30,000 ppm, preferably 3,000 to 20,000 ppm, and more preferably. Is added so as to be 5,000 to 15,000 ppm. Of course, it depends on the composition of the dicarboxylic acid and glycol component used, but it is generally 2 to 20 of the total glycol component.
It is within the range of mol%. If it is less than 2,000 ppm, the flame retardance is poor, and if it is more than 30,000 ppm, the flame retardant effect is saturated and various properties inherent to the polyester are significantly deteriorated, which is not preferable. Of course, it is also possible to once produce a high content polyester copolymer, mix it with an ordinary polyester so as to obtain a desired phosphorus content, and perform molding.

The phosphorus-containing bishydroxy compound represented by the general formula (I) of the present invention is usually a phosphorus compound represented by the following general formula (II) and a dihydroxy compound having an ester bond represented by the general formula (III). Is obtained by reacting at low temperature.

[Chemical 3]

[Chemical 4] (In the formulas (II) and (III), R is an alkyl group having 1 to 9 carbon atoms, an allyl group, an aralkyl group, a cycloalkyl group, A
Is a divalent aromatic organic residue (without halogen), R ₁
Represents an alkylene group having 2 to 4 carbon atoms, and m represents an integer of 1 to 2. )

Examples of the phosphorus compound represented by the general formula (II) include methylphosphonic acid dichloride, ethylphosphonic acid dichloride, butylphosphonic acid dichloride, i-propylphosphonic acid dichloride, hexamethylphosphonic acid dichloride, octylphosphonic acid dichloride, 2- Ethylhexylphosphonic acid dichloride,
Phenylphosphonic acid dichloride, m-tolylphosphonic acid dichloride, p-toluylphosphonic acid dichloride,
Examples include 3.5-xylylphosphonic acid dichloride, cyclohexylphosphonic acid dichloride, and the like. Among these, phenylphosphonic acid dichloride is particularly preferable in terms of heat resistance and light resistance.

As the aromatic dihydroxy compound having an ester bond represented by the general formula (III), a dicarboxylic acid having a divalent aromatic ring A as a skeleton and an ester derivative may be reacted with (a) glycol or (b). It can be easily obtained by subjecting an epoxy compound to an addition reaction or by reacting (ha) a carboxylic acid halide and a glycol. In the case of (a), examples of glycol include ethylene glycol and n
-Propylene glycol, i-propylene glycol,
Examples include 1.4-butanediol and diethylene glycol. Examples of the epoxy compound (b) include ethylene oxide and propylene oxide.

Any of these methods may be used, but (a)
This method is often used because it is a transesterification reaction which is one of the usual polyester production processes and can be easily extracted from that process. Further, it can be obtained by depolymerizing polyester. Such glycol or epoxy compound can be selected depending on the purpose and application,
When it is necessary to increase the phosphorus content of the resulting phosphorus-containing bishydroxy compound, ethylene glycol and ethylene oxide having a small number of carbon atoms are preferable. The reaction is adjusted so that the average value of m in the general formula (III) is 1 to 2, preferably 1.5 or less. When it exceeds 2, the physical properties of the polyester may be deteriorated or a side reaction may occur, which is not preferable. Needless to say, the amount less than 1 is not preferable because it inhibits the polymerization or reduces the reactivity with the phosphorus compound.

A constituting the skeleton of the dihydroxy compound of the general formula (III) is a divalent aromatic organic residue containing no halogen atom and the like, for example,

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8] (However, Y represents an alkylene group having 1 to 3 carbon atoms, an alkylidene group, O, S, SO ₂ ). Needless to say, an alkyl group having 1 to 3 carbon atoms, a sulfonic acid group, a phosphoric acid group, a metal salt thereof, or the like may be bonded to this skeleton. Examples of the dicarboxylic acid having such a skeleton include terephthalic acid, isophthalic acid, 2.6-naphthalenedicarboxylic acid, 1.5-naphthalenedicarboxylic acid, 4.
4-diphenyldicarboxylic acid, bis- (4-carboxyphenyl) ether, bis- (4-carboxyphenyl) sulfone, 5-sodium sulfoisophthalic acid, and the like are used, and one or more of these are mixed and used. You can also When the number of carbon atoms is too large, the phosphorus content of the general formula (I) is lowered and the flame retarding effect is reduced, so that the number of carbon atoms is 20 or less, preferably 15 or less. .. Among them, terephthalic acid, naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid and the like are preferable because they are excellent in thermal stability and flame retardant effect.

The phosphorus-containing bishydroxy compound of the general formula (I) can be easily obtained by reacting the phosphorus compound of the general formula (II) with the dihydroxy compound having an alcoholic hydroxyl group of the general formula (III). it can. For such a reaction, conventionally known techniques such as a solution method, a melting method or an interfacial reaction method can be applied. Among them, the solution method is preferable in terms of easy adjustment and easy purification. In the reaction, additives such as a heat stabilizer, an anti-coloring agent, a pigment, a reaction accelerator and a fluorescent agent may be used if necessary. Further, as the solvent for the solution method, those having a relatively low polarity are preferable, and examples thereof include tetrahydrofuran, trichlene, dichloroethane, benzene, toluene, xylene, chloroform, carbon tetrachloride,
Parkren etc. are mentioned.

Usually, it is well known that side reactions are likely to be generated in the reaction at high temperature, but the above-mentioned phosphorus compound of the general formula (II) is extremely reactive, and
Since the bishydroxy compound (III) is highly reactive with an alcoholic hydroxyl group, the reaction easily proceeds at low temperatures and the formation of by-products can be suppressed. Therefore,
The charge ratio can be adjusted arbitrarily, that is, n in the general formula (I) can be adjusted. If n is too large, the reactivity during polyester polymerization becomes poor, which is not preferable. In order to uniformly introduce the polyester into the main chain of the polyester, the average n is preferably adjusted to the range of 1 to 3, preferably 1 to 1.5.

Therefore, the charged amount during the reaction is 2 to 4/3 mol, preferably 2 to 5 / mol of the bishydroxy compound of the general formula (III) per 1 mol of the phosphorus compound of the general formula (II).
The range is 3 mol. As the number of moles approaches an equimolar ratio, the degree of polymerization n becomes a polymer of 4 or more. On the other hand, if the number of moles of the general formula (III) exceeds 2 moles, unreacted bishydroxy compound may be mixed in, which may cause deterioration of the physical properties of the polyester, which is not preferable.

The copolymer of the present invention is a low molecular weight compound having a degree of polymerization n of 3 or less, and both terminal groups each have a highly active ester-forming glycolic hydroxyl group. And is easily copolymerized to form a uniform linear polymer. In particular, as mentioned above, phosphonic acid glycol esters such as phenylphosphonic acid-
Bis-hydroxyethyl ester and the like are distilled out of the system at the time of polymerization and the residual rate of phosphorus in the copolymerized polyester is 40.
% Or less, in the general formula (I) of the present invention, R is a phenyl group, R ₁ is hydrogen, A is a chemical formula 5, and n = 1.0.

[Chemical 9] Even if the phosphorus-containing bis-hydroxy compound having a similar structure to the above structure, it was obtained without distillate during polycondensation, probably because it is a stable large molecule containing an ester bond in the already completed condensation form. It is surprising that the residual phosphorus ratio in polyester is 98% or more of the theoretical value.

[0028]

As described above, the flame-retardant polyester copolymer of the present invention has a phosphorus atom imparting flame-retardant property introduced into the main chain of polyester. It is useful because it does not elute or fall off during use of the molded product or during washing and the like, and the flame retardancy does not deteriorate. Further, it has excellent light resistance and whiteness without impairing the mechanical and thermal characteristics inherent in polyester and the texture of textiles, and has good dyeability. Further, since the atom imparting flame retardancy is only the phosphorus atom, even if the molded product comes into contact with the flame, no harmful gas is generated in the human body, and thus it is very safe and useful.

The flame-retardant polyester copolymer of the present invention is
Fibers and yarns can be spun, drawn or spun by ordinary methods and post-treated by ordinary methods, and weaving and knitting can be performed using ordinary looms and knitting machines without special consideration. In addition, high-class techniques such as mixed spinning or composite spinning with ordinary polyester or cationic dyeable polyester, or composite weaving with the above-mentioned ordinary fibers or other fibers such as cotton, polyester, acrylic, or the like having a multilayer structure It is possible to obtain high quality flame-retardant polyester products. Further, a molded product such as a film, foil or bottle can be easily obtained as a flame-retardant product by extrusion, compression or injection molding by a usual method. Illustrative examples of such fiber products and molded articles include thick fabrics, garments, carpets, curtains, bags, bottles, films, structural parts, and mechanically conductive parts.

[0030]

The present invention will be described in more detail with reference to the following examples. All "parts" in the examples mean "parts by weight". The intrinsic viscosity [η] was determined by a conventional method at 20 ° C in a mixed solvent of phenol / tetrachloroethane = 6/4.
The melting point was determined from the endothermic peak of DSC. In addition, flame retardancy was evaluated by the number of times of flame contact (JIS L-1
091 D) or the limiting oxygen index (JIS K-720
1) Measured and shown according to the method. As for light resistance, after irradiating with a carbon arc method fedometer for 40 hours, the original yarn is gray scale, the dyed one is a grade 5 which has no discoloration compared with the blue scale, and the one which is significantly discolored 1
It is shown by classifying into 5 grades. The whiteness was indicated by a color b value obtained by closely winding a thread on a black paper and measuring the color with a colorimetric color difference meter, as in the case of the lightfast sample.

Example 1 100 parts of dimethyl terephthalate, 75 parts of ethylene glycol and 0.04 part of zinc acetate were placed in a reaction vessel,
A transesterification reaction was carried out for 2 hours while continuously heating the methanol generated by heating from 150 ° C to 220 ° C to the outside of the system. Then, gradually reduce the pressure in the system to 200 mmH
The reaction was completed while the excess ethylene glycol was distilled off over 1 hour to obtain g, and thin-film distillation was carried out to obtain white crystals of bis-ω-hydroxyethyl terephthalate (purity 99.
5%) was obtained.

2.6 parts of this bis-ω-hydroxyethyl terephthalate and 2 parts of xylene were mixed with a stirrer, a dropping funnel, and N.
₂ Place in a reaction vessel equipped with an inlet tube and a distillation tube, and add N ₂
It heated and melt | dissolved in 110 degreeC, flowing a gas. Next, 1.0 part of phenylphosphonic acid dichloride was gradually added dropwise over 20 minutes while maintaining the internal temperature at 110 to 120 ° C. with stirring from a dropping funnel. The dihydroxy component is in a 2.0 mol ratio with respect to 1 mol of phenylphosphonic acid dichloride.
After reacting at the same temperature for 15 minutes, the temperature was raised to 130 ° C and the pressure in the system was gradually reduced to distill off xylene.
The phosphorus-containing bis-hydroxy compound (flame retardant A) was taken out for further 30 minutes at the same temperature and analyzed by NMR and liquid chromatography. As a result, it had the following structural formula.

[Chemical 10]

Next, 100 parts of dimethyl terephthalate, 72 parts of ethylene glycol and 0.04 part of zinc acetate are added to 150 parts.
The mixture was heated from 0 ° C to 220 ° C, and the produced methanol was continuously distilled out of the system to carry out a transesterification reaction for 3 hours. 16.0 parts of bishydroxy compound was added, the internal pressure was reduced while gradually raising the temperature, and finally 280 ° C,
Polycondensation was carried out at 0.3 mmHg for 3 hours, and then this polymer was extruded into a cord shape and cut into pellets having a size of 2.5 mmφ × 3 mm. No phosphorus compound, which is a flame retardant, was detected in the top lid of the polymerization kettle or in the distilled ethylene glycol, and no distillation outside the system was observed.

After drying the pellets to a moisture content of 0.005%, they were melt-spun in an extruder at a spinning temperature of 288 ° C. and a winding speed of 800 m / min, and subsequently a draw ratio of 3.9.
4 times, draw at a drawing speed of 1000 m / min with a roller heater at 85 ° C, set with a plate heater at 150 ° C and set at 75
A drawn yarn of d / 24f (P content = 7,500 ppm) was obtained.

Further, as the flame retardant, flame retardants B to F were synthesized by reacting the dihydroxy compound with phenylphosphonic acid dichloride in various molar ratios, and the same phosphorus content as the flame retardant A was added to the polyester. Copolymerization was performed in the same amount as A. These are melt spun and stretched to 75d
/ 24 f drawn yarn. Table 1 shows the results of measuring the intrinsic viscosity [η], melting point, number of times of flame contact and light resistance of the copolymerized polyester thus obtained.

The number of times of contact flame is determined by setting the filament bundle length to 22.
Cut into cm and collect 1g, fix one end, sandwich the other end with a hand drill, twist 20 times, fold it in half to make a twisted rod of about 10 cm in length, and then twist this rod Using J
It was measured according to the IS method.

[0037]

[Table 1] As shown in Table 1, those using the phosphorus-containing bishydroxy compound within the scope of the present invention had excellent whiteness, light resistance and flame retardancy with almost no inhibition of the polycondensation reaction. .. On the other hand, those outside the scope of the present invention (flame retardant No.
E and F) had problems such as inhibition of polymerization rate, coloring, and deterioration of light resistance.

Example 2 Various dihydroxy compounds were reacted with various phosphonic dichlorides in the same manner as in Example 1 at a molar ratio of 2: 1 to synthesize various flame retardants. Then, a copolyester was produced in the same manner as in Example 1 so that the phosphorus content was the same, and was spun and stretched in the same manner to obtain a filament of 75d / 36f. The results of performance evaluation of this product as in Example 1 are shown in Tables 2 and 3.

[0039]

[Table 2]

[Table 3] As shown in Tables 2 and 3, the copolyesters of the present invention are excellent in light resistance and flame retardancy. Among them, an allyl group having a P-substituent, for example, a phenyl group, has less decrease in viscosity and melting point and is excellent in heat resistance as compared with an alkyl group derivative.

Example 3 Using the flame retardant (A) of Example 1, various polyester copolymers were obtained in the same manner as in Example 1 except that the copolymerization amount was variously changed. 75 obtained by spinning and drawing in the same manner as in Example 1.
Table 4 shows the results of measuring the whiteness, light resistance, and number of times of flame contact of the d / 24f drawn yarn.

[0041]

[Table 4] As is clear from Table 4, the phosphorus content is 2,000 ppm
The following (No. 1) lacks in flame retardant performance, and even if the amount is more than necessary, the flame retardancy is saturated and, conversely, the physical properties of polyester are deteriorated. It can be seen that those within the scope of the invention have excellent performance.

Comparative Example 1 In Example 1, bis- (2-hydroxyethyl) phenylphosphonic acid oxide was synthesized by reacting with ethylene glycol instead of the aromatic dihydroxy compound.
This was subjected to polycondensation in the same manner as in Example 1. The phosphorus compound was distilled out during the polycondensation, and the phosphorus content in the obtained polyester was measured. As a result, the phosphorus residual rate was 29%. This polyester copolymer was spun and stretched according to Example 1 and the performance was measured. As a result, the number of flame contact was 2.1 times, which was inferior.

Comparative Example 2 According to Example 1 described in JP-A-53-68756, dimethyl terephthalic acid and ethylene glycol were subjected to transesterification reaction in the presence of zinc acetate dihydrate, and then phenylphosphonic acid was added. Then, antimony trioxide was added, and esterification and polymerization were performed under the described conditions to obtain a polyester copolymer. Significant phosphorus was detected in the reaction distillate. This polyester copolymer was spun and stretched, and the performance was measured. As a result, the number of times of flame contact was 3.2 and the color b value was 3.
5, the light resistance was inferior to grades 3 to 4.

Example 4 Two copolyester stretched yarns modified with the flame retardant A obtained in Example 1 and the flame retardant (No. H, I) of Example 2 were combined into a tubular knit. A tubular knitted fabric was obtained with a machine. These cylindrical knitted samples were used as Miketon Polyester Blue.
Table 5 shows the results of evaluation of the number of flame contacts after 20 times of high-pressure dyeing with FBL 2% owf and washing with a domestic washing machine and dry cleaning were repeated.

[0045]

[Table 5] As shown in Table 5, the flame-retardant copolyester of the present invention has excellent heat resistance and wash resistance.

Claims (3)

[Claims] 1. A general formula: (In the formula, R is an alkyl group having 1 to 9 carbon atoms, an allyl group, an aralkyl group, and a cycloalkyl group, R ₁ is an alkylene group having 2 to 4 carbon atoms, and A is a divalent aromatic organic residue ( (Not containing halogen), m is 1 to 2, and n is an integer of 1 to 3), and the phosphorus atom content in the polyester is 2,000 to 30, A flame-retardant polyester copolymer characterized by being copolymerized to a concentration of 000 ppm. 2. The polyester according to claim 1, comprising a bifunctional carboxylic acid component containing terephthalic acid or an ester-forming derivative thereof as a main component and a glycol component containing ethylene glycol or an ester-forming derivative thereof as a main component. Flame-retardant polyester copolymer. 3. A fiber, a film or a resin molded body made of the flame-retardant polyester copolymer according to claim 1.