JPH06228814A - Production of flame-retardant polyester fiber - Google Patents

Abstract

PURPOSE:To obtain a fiber of excellent whiteness and high light and washing fastness by effecting the polymerization of fiber-forming polyester as a phosphorus flame retarder containing a specific phosphorus-containing bis-hydroxy compound is added, then spinning the polymer. CONSTITUTION:Compound A containing more than 3wt.%, preferably 4 to 10wt.% (based on phosphorus atom) of a phosphorus-containing bishydroxy compound of the formula [R is 1-9 C alkyl or allyl; R1 is 2-4 C alkylene; A is a divalent aromatic residue (including no halogen); m is 1 to 2; n is an integer of 1 to 3] is added on polymerization of a fiber-forming polyester and the polymer is melt-spun into fiber. The content of phosphorus atom in the polyester fiber is set to at least 2,000ppm, preferably 5,000 to 15,000ppm.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a novel flame-retardant polyester fiber containing a phosphorus-based flame retardant.

Aromatic polyesters typified by polyethylene terephthalate have excellent mechanical properties and are extremely useful materials widely used as fibers, films and other plastic molded products. In parallel,
It has a drawback that it is easy to burn, and in recent years, with increasing awareness of fire, there is a strong demand for flame retardancy.
Further, the generation of toxic gas (cyan, halogen) at the time of combustion is more than the problem of flame retardancy, and development of a flame-retardant product that does not generate these toxic gas is desired.

[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.

Further, in the conventional kneading method, the flame retardant is sublimated or colored during molding, or the mechanical properties of the molded product are remarkably deteriorated. Furthermore, when a molded product such as a textile product is dry-cleaned, the flame retardant may come off or bleed out, resulting in a number of drawbacks such as deterioration in performance and hygiene due to contamination.

A so-called copolymerization method in which a phosphorus atom, which is one of the flame-retarding atoms in the main chain of the polyester molecule, is introduced 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 a method of adding phosphonic acid or phosphonic acid esters. However, since these phosphonates generally have a low boiling point, they have the drawbacks that they are distilled out of the system during polymerization, or three-dimensional side reactions occur during the production of polyester, making molding difficult or impossible. Japanese Patent Publication 36-20
No. 771 discloses a method in which a phosphonic acid bisglycol ester having a relatively high boiling point is added and copolymerized.
However, even though the boiling point is high, there are many cases where a cyclic low-boiling point substance is generated by self-condensation during the polymerization and volatilizes out of the system, and there is a drawback that the introduction rate into the polymer is low.

Japanese Patent Publication No. 53-13479 and Japanese Unexamined Patent Publication No. 50
-53354 discloses copolymerizing carboxyphosphinic acid. Such a phosphine compound has no volatility and has excellent flame resistance. However, the ester-forming functional group is a carboxyl group and a phosphate-bonded P group.
Due to the --OH group, the reaction rate is slightly different and the uniformity is somewhat poor. Further, in terms of heat resistance, the P-O-C bond has some disadvantages inferior to the P-C bond. In addition, 55
-41610, derived from oxaphosphane oxide and itaconic acid. A method of copolymerizing a phosphorus-containing dicarboxylic acid compound is disclosed. This method also has excellent flame resistance. However, since it is a complex polycyclic compound, it has a drawback that crystallinity, melting point, physical properties, etc. are deteriorated due to steric hindrance, or molecular scission is easily caused by slight light or heat.

German Patent Application Publication No. 1232348 discloses a polyester copolymerized with bis- (p-carboxyphenyl) -phosphinic acid, which is intended for polyester modification such as dyeing improvement. It has a low content and hardly imparts flame retardancy. On the other hand, US Patent Application Publication No. 4127566 discloses a polyester copolymerized with bis- (carboxyethyl) methylphosphine oxide. Although this compound exhibits good flame retardancy, it has the drawbacks that the melting point of the copolymer polymer is largely lowered and the heat resistance thereof is rather low.

[0008]

The object of the present invention is to remedy the drawbacks of the prior art and to find an effective and pollution-free flame-retardant copolymerization component in a small amount.

The object of the present invention is to provide a flame-retardant polyester fiber having excellent fiber moldability and excellent whiteness, light resistance and washing resistance without deteriorating the mechanical properties and thermal properties inherent in polyester. It is to provide an industrially inexpensive manufacturing method.

[0010]

[Means for Solving the Problems]

That is, the present invention has the general formula

[Chemical 2] (In the formula, R is an alkyl group having 1 to 9 carbon atoms, an allyl group, an aralkyl group, a cycloalkyl group, R ₁ is an alkylene group having 2 to 4 carbon atoms, and A is a divalent aromatic organic residue ( A halogen-free compound), m is 1 to 2, and n is an integer of 1 to 3), and a compound A containing at least one phosphorus-containing bishydroxy compound represented by the formula: A method for producing a flame-retardant polyester fiber, which comprises blending at the time of polymerizing a fiber-forming polyester so that the phosphorus atom content is at least 2000 ppm, polymerizing, and then spinning.

The phosphorus-containing bishydroxy compound represented by the general formula (I) of the present invention is usually represented by the general formula

[Chemical 3] A phosphorus compound represented by

[Chemical 4] It can be obtained by reacting with a dihydroxy compound having an ester bond represented by (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 (not containing halogen), R ₁ is an alkylene group having 2 to 4 carbon atoms, and m is 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), (i) glycol is reacted with dicarboxylic acid and ester derivative having a divalent aromatic ring A as a skeleton, 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.

As the glycol in the case of (a), for example, ethylene glycol, n-propylene glycol, i-
Propylene glycol, 1.4-butanediol, diethylene glycol and the like can be mentioned. 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 can be easily extracted from the step because it is a transesterification reaction which is one of the usual polyester production steps. 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 phosphorus-containing bishydroxy compound produced, 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, if it is less than 1, it is not preferable because it hinders the polymerization or reduces the reactivity with the phosphorus compound.

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

[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 ). Of course, 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, and 4.
4-diphenyl dicarboxylic acid, bis- (4-carboxyphenyl) ether, bis- (4-carboxyphenyl) sulfone, 5-sodium sulfoisophthalic acid, and the like can be mentioned and used by mixing one or more kinds thereof. You can also If the number of carbon atoms is too large, the phosphorus content in the general formula (I) is lowered, and the flame retardant effect is reduced, so that the number of carbon atoms is preferably 20 or less, more preferably 15 or less. . Among them, terephthalic acid, naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid and the like and their derivatives 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 easiness of adjustment and easiness of purification. During 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 relatively low polarity are preferable, and examples thereof include tetrahydrofuran, trichlene, dichloroethane, benzene, toluene, xylene, chloroform, carbon tetrachloride,
Parklen etc. are mentioned.

Usually, it is well known that side reactions are likely to occur in reactions at high temperatures, but the above-mentioned phosphorus compounds of the general formula (I) are extremely reactive, and the general formula ( Since the bishydroxy compound I) 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.

Accordingly, the amount of the charge at the time of the reaction is 2 to 4/3 mol, preferably 2 to 5 / mol of the bishydroxy compound of the general formula (I) per mol of the phosphorus compound of the general formula (I).
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 (I) exceeds 2 moles, unreacted bishydroxy compound may be mixed, 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 have highly active ester-forming glycolic hydroxyl groups. 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 the general formula (IV), and n = 1.
Even if the phosphorus-containing bishydroxy compound having a similar structure having the structure of the general formula (V) consisting of 0 is a stable large molecule containing an ester bond in a completely completed form, it may be due to polycondensation. There is no distillate, and the residual rate of phosphorus in the obtained polyester is very high.

The compound A containing the compound represented by the above general formula may be a compound having any shape and structure. For example, a compound that is ester-bonded with another compound, a compound that is reacted with an amide bond, a compound that is reacted with a urethane bond, a compound that is reacted with an ether bond, and the like can be adopted.

As an ester-bonded product, two O
This can be achieved by reaction with a compound having an H group. Preferably, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and the like having the same skeleton structure as polyester fibers, and derivatives and ester derivatives thereof, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,
Aromatic dicarboxylic acids such as 1,5-naphthalenedicarboxylic acid and 4,4-diphenyldicarboxylic acid, and their derivatives, their alkyl esters, allyl esters, and ethylene glycol ester derivatives.

The reaction product by an amide bond can be achieved by a reaction with a compound having two amino groups.

The composition is set so that the phosphorus atom content in the compound A is at least 3% by weight, preferably 3.5% by weight, and more preferably 4 to 10% by weight. If the content of phosphorus atoms is less than 3% by weight, the amount of compound A compounded in the polyester fiber in order to exhibit flame retardancy increases, causing thermal deterioration of the fiber, deterioration of mechanical properties, and increase in coloring. Leads to.

If the degree of polymerization of the compound A is too low, the heat resistance will be poor, and the deterioration will be remarkable when mixed with the polyester.
Further, if the degree of polymerization is too high, there are drawbacks that a large amount of power and equipment are required at the time of mixing, the mixing cannot be sufficiently achieved, and the homogeneity of the fibers is deteriorated. The degree of polymerization is preferably 5 or more, more preferably 10
~ 100. The degree of polymerization is appropriately selected depending on the compounding method of the present compound A. For example, when polymerizing polyester,
The degree of polymerization is preferably 50 or less when it is added at an early stage such as the end of transesterification, and the degree of polymerization is preferably 20 to 70 when blended after the middle stage of polyester polymerization.

As the fiber-forming polyester of the present invention, commonly used polyester can be used. That is, a polyester obtained by copolymerizing the following dicarboxylic acid or its derivative with glycol can be used.
For example, as dicarboxylic acid components, 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-sodium sulfoisophthalic 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 one or more of these aromatic dicarboxylic acids and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decamethylenedicarboxylic acid and other ester-forming derivatives It can be used by mixing a small amount up to 10 mol%.

On the other hand, as glycol components, 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. Among them, ethylene glycol, 1.4-butanediol, which is useful, may be used as a main component, and one or more other glycol components and ester moldable derivatives may be mixed and used in a small amount up to 10 mol% of the diol component. it can.

If desired, an oxycarboxylic acid component having a carboxylic acid group and an alcohol group in one molecule, such as 4-oxybenzoic acid, 4-hydroxyethoxybenzoic acid, oxypivalic acid, etc., can also be used.

If necessary, a small amount of a monofunctional compound, such as benzoic acid, benzoylbenzoic acid, acetic acid, methoxypolyethylene glycol, or a trifunctional or higher functional compound,
For example, glycerin, pentaerythritol, phosphoric acid compounds and their ester-forming derivatives can be added.

The degree of polymerization of polyester may be such that it can be used for ordinary fibers, but the intrinsic viscosity [η] is preferably 0.5 or more, more preferably 0.6 to.
1.5, particularly preferably 0.65 to 1.0.

The compound A is added to the polyester at the time when the polymerization of the fiber-forming polyester is started. Preferably,
It is carried out after completion of transesterification in which the terminal of dicarboxylic acid such as terephthalic acid is substituted with ethylene glycol. More preferably, it is added at the time when the polymerization of polyester is not completed, for example, before the intrinsic viscosity [η] is 0.4.
More preferably, [η] is 0.1 to 0.3. 0.
When it is less than 1, there are many alcohol components such as ethylene glycol in the polyester polymerization system, and depolymerization-scattering of the compound A occurs. When [η] is more than 0.4, the polyester of the compound A is evenly distributed. Hard to be introduced.

The compounding ratio of the compound A is not particularly limited as long as it does not deteriorate the mechanical properties, thermal properties, flame retardancy and the like of the flame-retardant fiber, but preferably 25% by weight or less relative to the polyester, It is more preferably 15% by weight or less.

In the spinning, pigments, matting agents, optical brighteners, heat stabilizers, UV absorbers, antioxidants, antistatic agents, organic amines, organic carboxylic acid amides, etc. Various ether bond inhibitors, etc. may be used if necessary.

The amount of the phosphorus-containing dicarboxylic acid component represented by the general formula (I) is at least 2,000 ppm, preferably 3,000 to 20,000 ppm, more preferably the phosphorus atom content in the obtained polyester fiber. It is added so as to be 5,000 to 15,000 ppm. If it is less than 2,000 ppm, flame retardance is poor,
When it is more than 000 ppm, the flame retardant effect is saturated and various properties inherent to polyester are significantly deteriorated, which is not preferable.

Spinning can be carried out by a usual spinning method, but any of spin draw, high speed spinning and composite spinning can be adopted. The thickness of the fiber is usually 1 denier or more, but thinner fibers can be spun depending on the application. Regarding the fiber cross section, not only a round cross section but also a modified cross section fiber such as a triangular cross section, a flat cross section, a square cross section, a polygonal cross section, a hollow cross section, or the like is possible.

[0037]

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 other treatments, and it does not deteriorate in flame retardant performance and is durable. Further, it has excellent light resistance and whiteness without impairing the original mechanical and thermal characteristics of 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, which is extremely 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 can be post-treated by ordinary methods, and ordinary weaving machines and knitting machines can be used for weaving and knitting 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, films, foils, or molded products such as bottles can be easily obtained as flame-retardant products by extrusion, compression or injection molding in a usual manner. Examples of such fiber products and molded products include thick fabrics, clothing, carpets, curtains, duck, bottles, films, structural parts, mechanically conductive parts and the like.

[0039]

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 according to the method and shown.

Example 1

Bishydroxyethyl terephthalate (BHE
T) 70 parts and general formula

[Chemical 10] 30 parts by weight of phosphorus-containing compound, 0.06 antimony trioxide
After being charged into a polymerization vessel and melted, the internal pressure was reduced while gradually raising the temperature, and finally polymerization was carried out at 235 ° C. and 0.3 mmHg for 3 hours. The polymer is then extruded into a cord and cut to 2.5
Compound A was obtained by making pellets having a size of mmφ × 3 mm.

Then, a usual polyester polymer is polymerized using bishydroxyethyl terephthalate (BHET) as a starting material and antimony trioxide as a polymerization catalyst.
After heating and melting at 0 ° C., the internal pressure was reduced while gradually raising the temperature, and finally polymerization was allowed to proceed at 267 ° C. and 0.3 mmHg. The progress of the polymerization was monitored by the rotation torque of the stirrer. When the intrinsic viscosity [η] reached 0.2 on the way, the compound A was added to the final polymer in an amount shown in Table 1 to continue the polymerization.
When the intrinsic viscosity [η] of the content reached 0.6, the content was extruded into a cord and cut into pellets having a size of 2.5 mmφ × 3 mm.

Each of the pellets was dried to a water content of 0.005%, melt-spun in an extruder at a spinning temperature of 285 ° C. and a winding speed of 950 m / min, and subsequently a ratio of 3.87.
Double, draw at a draw speed of 750 m / min with a roller heater at 80 ° C., set with a plate heater at 150 ° C., 75 d
A drawn yarn of / 24f was obtained.

Two drawn yarns were combined, knitted by a knitting machine and refined, and then tested for flame retardancy and light resistance. That is, as for the flame retardancy, the number of times of flame contact by the 45 ° coil method was obtained by winding a cylindrical knitted fabric in a cut rod shape so that the weight was 1 g and the length was 100 mm.

[0045]

[Table 1]

Example 2 Each of the phosphorus-containing compounds shown in Table 2 was 4% by the method of Example 1.
A copolymer containing the same was obtained, and the P content in the final polymer was 670 during the polymerization of polyester in the same manner as in the method of Example 1.
It was blended so as to be 0 ppm to complete the polymerization. The polymer was recovered and spun in the same manner as in Example 1 to obtain 75d / 24f fibers. Various performances are shown in Table 2.

[0047]

[Table 2]

[Chemical 9]

[Chemical 11]

[Chemical 12]

Claims (4)

[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, a cycloalkyl group, R ₁ is an alkylene group having 2 to 4 carbon atoms, and A is a divalent aromatic organic residue ( A halogen-free compound), m is 1 to 2, and n is an integer of 1 to 3), and a compound A containing at least one phosphorus-containing bishydroxy compound represented by the formula: A method for producing a flame-retardant polyester fiber, which comprises blending at the time of polymerizing a fiber-forming polyester so that the phosphorus atom content is at least 2000 ppm, polymerizing, and then spinning. 2. The method for producing a flame-retardant polyester fiber according to claim 1, wherein the compound A is a copolymer having an ester bond. 3. The method for producing a flame-retardant polyester fiber according to claim 1, wherein the compound A is blended after the transesterification of the fiber-forming polyester is completed. 4. The method for producing a flame-retardant polyester fiber according to claim 1, wherein the compound A is compounded at the time when the intrinsic viscosity [η] during the condensation polymerization of the fiber-forming polyester does not exceed 0.4.