JPH0693096A - Production of flame retardant polyester - Google Patents

Abstract

PURPOSE:To rapidly obtain a polymer having a high polymerization degree without any deterioration in color tone and rise in cost by carrying out the solid-phase polymerization of a polyester, consisting essentially of ethylene terephthalate unit and containing a bifunctional organophosphorus compound and a spirophosphorus compound. CONSTITUTION:A polycondensation reactor is charged with a 50wt.% solution of a bifunctional organophosphorus compound expressed by formula I, etc., in ethylene glycol, a spirophosphorus compound expressed by formula II (R<1> and R<2> are 6-25C hydrocarbon), bis(beta-hydroxyethyl)terephthalate and its low polymer obtained by the esterifying reaction of terephthalic acid with ethylene glycol and a compound such as Sb, Ge or Sn as a catalyst is then added thereto. The polycondensation is carried out at 285 deg.C under 0.4Torr to provide a prepolymer having >=500ppm content of bifunctional organophosphorus compound expressed in terms of P atoms, 0.01-5wt.% content of spirophosphorus compound copolymerized therein and 0.42-0.72 intrinsic viscosity. The prepolymer is then subjected to the solid-phase polymerization at a temperature lower than the melting point thereof by >=10 deg.C until the intrinsic viscosity attains >=0.75 to afford the objective flame retardant polyester.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for rapidly producing a flame-retardant polyester having a high degree of polymerization.

[0002]

BACKGROUND OF THE INVENTION Polyethylene terephthalate has excellent mechanical properties and chemical properties, and therefore, in addition to fibers for clothing, industrial use, etc., molded products such as films for magnetic tapes, photography, condensers, bottles, etc. Widely used for. From the viewpoint of fire prevention, the demand for flame retardancy of synthetic fibers and various plastic products is increasing.
Flame-retardant polyester fibers are used in clothing for the elderly, children's clothing, seats for vehicles, etc. to increase the effect. Although various attempts have been made to impart flame retardancy to polyesters, a method of copolymerizing an organic phosphorus compound is considered to be most effective (Japanese Patent Publication Nos. 55-41610 and 53-13479, JP-A-62-120171, JP-A2-1730, etc.). by the way,
When used as a fiber for industrial materials, the degree of polymerization of polyester needs to be higher than that for clothing in order to increase the strength of the yarn. For that purpose, a method in which melt-polymerized polyester is further solid-phase polymerized to increase the degree of polymerization is general.

On the other hand, in recent years, the need for flame-retardant safety nets and safety meshes has been increasing. However, the polyester copolymerized with the phosphorus compound as described above has a solid phase polymerization rate far higher than that of ordinary polyesters. Is slow. In addition, since the copolyester has a low melting point, the solid phase polymerization temperature must be set lower than that in the case of ordinary polyethylene terephthalate. Therefore, there has been a problem that the solid phase polymerization requires a long time and the color tone of the polyester is deteriorated. Further, there is a problem in that the manufacturing cost increases because the solid phase polymerization takes time.

[0004]

DISCLOSURE OF THE INVENTION The present invention aims at accelerating the solid phase polymerization rate of a polyester copolymerized with an organic phosphorus compound,
An object of the present invention is to provide a method capable of producing a flame-retardant polyester having a high degree of polymerization without deteriorating the color tone and increasing the cost.

[0005]

The present invention solves the above-mentioned problems and has the following constitution. Mainly composed of ethylene terephthalate units, a bifunctional organic phosphorus compound is copolymerized in an amount of phosphorus atom of 500 ppm or more,
Characterized by solid-state polymerization of a polyester having an intrinsic viscosity of 0.42 to 0.72 containing 0.01 to 5% by weight of a spiroline compound represented by the formula (1) at a temperature 10 ° C or more lower than its melting point until the intrinsic viscosity becomes 0.75 or more And a method for producing a flame-retardant polyester.

[0006]

[Chemical 2]

The present invention will be described in detail below. As the main component forming the polyester of the present invention, terephthalic acid and ethylene glycol (both include ester-forming derivatives) are used.
-Sodium sulfoisophthalic acid, diethylene glycol, propylene glycol, 1,4-butanediol, 1,
4-Cyclohexanedimethanol, pentaerythritol, 4-hydroxybenzoic acid, naphthalenedicarboxylic acid and the like may be used together as a small amount as a copolymerization component.

The bifunctional organic phosphorus compound has the following formula
Examples thereof include compounds represented by (a) to (d).

[0009]

[Chemical 3]

[In the formula, R ³ and R ⁷ are hydrocarbon groups having 1 to 18 carbon atoms, R ⁴ and R ⁵ are hydrocarbon groups or hydrogen atoms having 1 to 18 carbon atoms, and A ¹ is a divalent organic group. , A ² is a trivalent organic residue, R ⁶ ,
R ⁸ represents an ester-forming group, and R ⁹ represents a hydrocarbon group having 1 to 18 carbon atoms. The compounds (c) and (d) may be acid anhydrides.

Preferred specific examples of the compound of the formula (a) include dimethyl phenylphosphonate, diphenyl phenylphosphonate and the like.

Preferred specific examples of the compound of formula (b) include (2-carboxyethyl) methylphosphinic acid,
(2-carboxylethyl) phenylphosphinic acid,
Examples thereof include methyl (2-methoxycarboxyethyl) phenylphosphinate, methyl (4-methoxycarbonylphenyl) phenylphosphinate, and ethylene glycol ester of [2- (β-hydroxyethoxycarbonyl) ethyl] methylphosphinic acid.

Preferred specific examples of the compound of the formula (c) include the following compounds.

[0014]

[Chemical 4]

Preferred specific examples of the compound of the formula (d) include the following compounds.

[0016]

[Chemical 5]

The above-mentioned organophosphorus compound is added and copolymerized when a polyester is produced by a conventional method. That is, when a polyester is produced from terephthalic acid or dimethyl terephthalate and ethylene glycol by an esterification or transesterification reaction and a polycondensation reaction, it is added at any stage from the esterification or transesterification reaction to the beginning of the polycondensation reaction. can do. Also,
It may be added in the form of a monomer, oligomer or polymer reacted with an acid component such as terephthalic acid or isophthalic acid.

The amount of the organic phosphorus compound added is 500 ppm or more, preferably 1000 to 2000, as phosphorus atoms in the polyester.
It is necessary to set the content to 0 ppm. When the amount of the organic phosphorus compound is less than 500 ppm, the flame resistance of the polyester is insufficient, and when it is too large, physical properties of the polyester may be impaired, such as impairing the physical properties of the obtained polyester.

In the present invention, the spiroline compound represented by the above formula (1) is contained in order to accelerate the solid phase polymerization rate of the polyester copolymerized with the organic phosphorus compound.

Preferred specific examples of the spiroline compound include "Ultranox 626A" represented by the following formula (i) manufactured by GE Chemical Co., Ltd. and "Adeka Stab PEP-36 represented by the Asahi Denka Co., Ltd. represented by the following formula (ii). , "Weston 618" manufactured by BorgWarner Chemical Company represented by the following formula (iii) and the like, and the compound of the formula (i) is particularly preferable.

[0021]

[Chemical 6]

The amount of such spiroline compound added is
It is necessary to set it to 0.01 to 5% by weight with respect to the polyester. If the amount is less than 0.01% by weight, the effect of substantially increasing the solid-phase polymerization rate is not substantially obtained.

The spiroline compound can be added at any stage from the esterification or transesterification reaction to the end of the polycondensation reaction during the production of the polyester.
Polycondensation reaction when producing polyester is usually 0.01 ~
260 to 310 ℃ under reduced pressure of 10 torr, preferably 275 to 2
It is carried out at a temperature of 90 ° C. until a desired intrinsic viscosity is obtained.

Further, the polycondensation reaction is carried out in the presence of a catalyst, and as a catalyst, a metal such as antimony, germanium, tin, titanium, zinc, aluminum, magnesium, calcium, manganese, or cobalt which has been conventionally used is used. In addition to the compounds, organic sulfonic acid compounds such as sulfosalicylic acid and o-sulfobenzoic anhydride are preferably used. The catalyst is added in an amount of 1 × 10 ⁻⁵ to 1 × 10 ⁻² mol, preferably 5 × 10 ^{−5 to} 5 × 10 ⁻³ mol, and most preferably 1 ×, relative to 1 mol of the acid component constituting the polyester. 10 ^{-4 to} 3 x 10
^-3 mol.

In the present invention, a cobalt compound,
Additives such as fluorescent agents, color improving agents such as dyes, pigments such as titanium dioxide, ultraviolet absorbers for the purpose of improving light resistance, light stabilizers and the like may be contained.

For industrial materials such as safety nets, it is usually necessary to use a high degree of polymerization polyester having an intrinsic viscosity of 0.75 or more. For that purpose, it is necessary to once make a polyester (prepolymer) having an intrinsic viscosity of 0.42 to 0.72 produced by melt polymerization as described above into chips, and solid-phase polymerize this by a conventional method. If the intrinsic viscosity is less than 0.42, solid-state polymerization takes time and is not economical, and the intrinsic viscosity of melt polymerization is 0.72.
In order to exceed this, it is necessary to polymerize at high temperature for a long time, which is not a good idea.

It is necessary to carry out the solid phase polymerization under an inert gas atmosphere or under a reduced pressure of 5 Torr or less, and the solid phase polymerization temperature is 10 ° C. or more lower than the melting point of the polymer, preferably 180 to 225 ° C. is there. Solid phase polymerization at a temperature higher than this is not preferable because the polymer is fused.

The polyester obtained by the method of the present invention is
It is preferably used for the production of fibers for industrial materials such as safety nets and meshes, and those containing a large amount of organic phosphorus compounds can also be used as flame retardants for polyester.

[0029]

According to the method of the present invention, an organic phosphorus compound is copolymerized to increase the solid phase polymerization rate of polyester to the same level as that of polyethylene terephthalate. Although the reason for this is not clear, it is recognized that the spiroline compound, which originally functions as a heat stabilizer, suppresses the thermal decomposition of the polymer to accelerate the solid phase polymerization rate.

[0030]

EXAMPLES Next, the present invention will be described in detail with reference to examples. The characteristic values of polyester in the examples were measured as follows. Intrinsic viscosity [η] This is the value obtained from the solution viscosity measured at a temperature of 20.0 ° C using an equal weight mixture of phenol and ethane tetrachloride as a solvent. Phosphorus atom content (P content) The content of phosphorus atom in the polyester was quantified by a fluorescent X-ray method. Flame retardance The yarn obtained by spinning and drawing according to a conventional method is made into a tubular knitted fabric, 1 g of which is rolled into a length of 10.0 cm and inserted into a wire coil with a diameter of 10.0 mm, and held at an angle of 45 degrees, Ignite with a micro burner (caliber 0.64 mm) from the lower end, repeat the ignition again when the fire source is distant and extinguish the fire, find the number of ignitions required until all samples burn out, The average value (number of times of flame contact) was obtained and evaluated. Melting point (Tm) and glass transition point (Tg) Using a differential scanning calorimeter (DSC-2 type manufactured by Perkin Elmer Co., Ltd.), the temperature was raised at 20 ° C./min.

Example 1 12 kg of a 50 wt% ethylene glycol solution of the organophosphorus compound of the above formula (a), 121 g of the spiroline compound of the above formula (i),
Bis (β-hydroxyethyl) terephthalate obtained by the esterification reaction of terephthalic acid and ethylene glycol and 57 kg of a low polymer thereof were charged into a polycondensation reactor and used as a catalyst in an amount of 2 × 10 ^-4 per 1 mol of the acid component. Molar dimethyltin maleate was added and polycondensed at 285 ° C and 0.4 torr.
The obtained polyester (prepolymer) has [η] 0.6
7, Tm 242 ° C., Tg 68 ° C., P content was 7960 ppm. Then, this polyester is added to 5 torr according to a conventional method,
Solid phase polymerization was carried out at 220 ° C. for 24 hours to obtain a polyester of [η] 1.12. The obtained polyester is melt-spun at 298 ° C,
Then, after stretching and heat-treating at a temperature of 200 ° C by 5.3 times, 5%
After relaxing at a relaxation rate of 1,500d /
A 120 f filament yarn was obtained. This yarn is strong
It had 10.4 g / d, elongation of 20%, and the number of flame contact was 5.4 times, and had sufficient flame resistance.

Examples 2 to 10 and Comparative Examples 1 to 6 The same tests as in Example 1 were carried out by changing the kinds and addition amounts of the organic phosphorus compound and the spiroline compound. The results are shown in Table 1 together with the results of Example 1.

[0033]

[Table 1]

[0034]

According to the present invention, a flame-retardant polyester having a high degree of polymerization can be rapidly produced without impairing the excellent physical properties of the polyester.

Claims (1)

[Claims] 1. An ethylene terephthalate unit as a main component, and a bifunctional organophosphorus compound having a phosphorus content of 500 p
Polyester having an intrinsic viscosity of 0.42 to 0.72 containing 0.01 to 5% by weight of the spiroline compound represented by the formula (1) and having an intrinsic viscosity of 0.75 or more at a temperature 10 ° C or more lower than its melting point. A method for producing a flame-retardant polyester, characterized in that solid-state polymerization is performed. [Chemical 1]