JP3150211B2 - Method for producing flame-retardant polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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]

2. Description of the Related Art Polyethylene terephthalate has excellent mechanical properties and chemical properties, and therefore, in addition to fibers for clothing and industrial use, molded products such as films or bottles for magnetic tapes, photographs, and capacitors. Widely used for applications. From the viewpoint of fire prevention, there is an increasing demand for flame retardancy of synthetic fibers and various plastic products.
Flame-retardant polyester fibers are used in clothing for the aged, children's clothing, vehicle seats, etc., and have been effective. In the past, various attempts have been made to impart flame retardancy to polyesters, but the method of copolymerizing an organic phosphorus compound is considered to be the most effective (Japanese Patent Publication No. 55-41610, Japanese Patent Publication No. 53-13479, JP-A-62-172017, JP-A-2-1730, etc.). by the way,
When used as a fiber for industrial materials, it is necessary to increase the degree of polymerization of polyester higher than that for clothing to increase the strength of the yarn. For this purpose, a method in which the melt-polymerized polyester is further solid-phase polymerized to increase the degree of polymerization is generally used.

[0003] On the other hand, in recent years, the necessity of flame retardation of safety nets and safety meshes has been increasing. However, polyesters obtained by copolymerizing the above-mentioned phosphorus compounds have much higher solid-state polymerization rates than ordinary polyesters. Is slow. In addition, since the copolyester also has a low melting point, the solid-state polymerization temperature must be set lower than that of ordinary polyethylene terephthalate. Therefore, there is a problem that a long time is required for the solid phase polymerization, and the color tone of the polyester is deteriorated. In addition, there is a problem that the production cost increases because the solid-phase polymerization takes time.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to increase the solid phase polymerization rate of a polyester obtained by copolymerizing 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 or increasing the cost.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and its structure is as follows. Based on ethylene terephthalate units, bifunctional organic phosphorus compounds are copolymerized in an amount of 500 ppm or more as phosphorus atoms,
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), is subjected to solid-state polymerization at a temperature lower than its melting point by 10 ° C or more until the intrinsic viscosity becomes 0.75 or more. Method for producing flame-retardant polyester.

[0006]

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Hereinafter, the present invention will be described in detail. As the main components 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,
A small amount of 4-cyclohexanedimethanol, pentaerythritol, 4-hydroxybenzoic acid, naphthalenedicarboxylic acid, or the like may be used in combination as a copolymerization component.

The bifunctional organophosphorus compound is represented by the following formula:
Compounds represented by (a) to (d) are mentioned.

[0009]

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Wherein R ³ and R ⁷ are a hydrocarbon group having 1 to 18 carbon atoms, R ⁴ and R ⁵ are a hydrocarbon group or a hydrogen atom 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 in the form of an acid anhydride.

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 the formula (b) include (2 - carboxyethyl) methylphosphinic acid,
(2 - carboxyethyl) phenylphosphinic acid, (2
- methoxycarbonylethyl) phenyl phosphine, methyl (4-methoxycarbonylphenyl) phenyl phosphinic acid methyl, ethylene glycol esters of [2-(beta-hydroxyethoxy-carbonyl) ethyl] methyl phosphinate.

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

[0014]

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

[0016]

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The organic phosphorus compound as described above is added and copolymerized when a polyester is produced by a conventional method. That is, when producing a polyester from terephthalic acid or dimethyl terephthalate and ethylene glycol by esterification or transesterification and polycondensation, it is added at any stage from the esterification or transesterification to the initial stage of the polycondensation. 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 at least 500 ppm as a phosphorus atom in the polyester, preferably from 1,000 to 2,000.
It is necessary that the content be 0 ppm. If the amount of the organic phosphorus compound is less than 500 ppm, the flame resistance of the polyester is insufficient, and if the amount is too large, physical properties of the obtained polyester may be impaired, and problems may occur in the physical properties of the polyester.

In the present invention, a spiro phosphorus compound represented by the above formula (1) is contained in order to increase the solid phase polymerization rate of a polyester obtained by copolymerizing an organic phosphorus compound.

Preferred specific examples of the spiroline compound include “Ultra Knox 626A” manufactured by GE Chemical Co. represented by the following formula (i), and “ADK STAB PEP-36” manufactured by Asahi Denka Kogyo Co., Ltd. represented by the following formula (ii). And “Weston 618” represented by the following formula (iii) manufactured by BorgWarner Chemical Co., Ltd., and the compound of the formula (i) is particularly preferable.

[0021]

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The amount of such a spiroline compound is as follows:
It is necessary to be 0.01 to 5% by weight based on the polyester. If the amount is less than 0.01% by weight, there is substantially no effect of increasing the solid-state polymerization rate, and if it exceeds 5% by weight, not only the effect is saturated, but also the color tone of the polyester deteriorates, which is not preferable.

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

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

In the present invention, a cobalt compound,
Additives such as a colorant such as a fluorescent agent and a dye, a pigment such as titanium dioxide, an ultraviolet absorber for improving light resistance, and a light stabilizer may be added.

For use in industrial materials such as safety nets, it is usually necessary to use a high polymerization degree polyester having an intrinsic viscosity of 0.75 or more. For that purpose, it is necessary to once chip the polyester (prepolymer) having an intrinsic viscosity of 0.42 to 0.72 produced by melt polymerization as described above, and subject it to solid-phase polymerization by an ordinary method. If the intrinsic viscosity is less than 0.42, solid-state polymerization takes a long time and is not economical, and the intrinsic viscosity becomes 0.72 in melt polymerization.
In order to exceed the above, polymerization must be carried out at a high temperature for a long time, which is not advantageous.

The solid-phase polymerization is carried out in an inert gas atmosphere or under a reduced pressure of 5 torr or less, and the solid-state polymerization temperature needs to be 10 ° C. or more lower than the melting point of the polymer, preferably 180 to 225 ° C. is there. If the solid phase polymerization is carried out at a temperature higher than this, the polymer is fused, which is not preferable.

The polyester obtained by the method of the present invention is
Safety net, suitably used in the production of fibers for industrial materials such as a mesh, those containing a large amount of organic phosphorus compounds as possible out also be used as a flame retardant for polyesters.

[0029]

According to the method of the present invention, the solid phase polymerization rate of polyester is increased to the same level as that of polyethylene terephthalate by copolymerizing an organic phosphorus compound. Although the reason for this is not clear, it is recognized that the spirophosphorus compound which originally functions as a heat stabilizer suppresses the thermal decomposition of the polymer, thereby accelerating the solid-state polymerization rate.

[0030]

Next, the present invention will be described specifically with reference to examples. In the examples, the characteristic values of the polyester 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 phosphorus atom content in the polyester was determined by a fluorescent X-ray method. Flame retardancy The yarn obtained by spinning and drawing according to a conventional method is made into a tubular knitted fabric, 1 g of the yarn is rolled to a length of 10.0 cm, inserted into a wire coil having a diameter of 10.0 mm, and held at an angle of 45 degrees. When ignited with a micro burner (caliber 0.64 mm) from the lower end, if the fire was extinguished by moving away from the fire source, re-ignition was repeated, and the number of ignitions required until all the samples were completely burned was determined. The average value (the number of times of flame contact) was determined and evaluated. Melting point (Tm) and glass transition point (Tg) Measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (Model DSC-2, manufactured by PerkinElmer).

Example 1 12 kg of a 50% by weight solution of the organophosphorus compound of the above formula (a) in ethylene glycol, 121 g of the spirophosphorus 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 2 × 10 ⁻⁴ was used as a catalyst per 1 mol of the acid component. Mole of dimethyl tin 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: 7960 ppm. Then, the polyester was subjected to 5 torr according to a conventional method,
Solid phase polymerization was performed at 220 ° C. for 24 hours to obtain a polyester having [η] 1.12. The obtained polyester is melt spun at 298 ° C,
After a stretch heat treatment of 5.3 times at a temperature of 200 ° C, 5%
After relaxing at the relaxation rate of
A filament yarn of 120f was obtained. This yarn has strength
At 10.4 g / d and elongation of 20%, the number of times of flame contact was 5.4, indicating that it 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 types and amounts of the organic phosphorus compounds and spiro phosphorus compounds. Table 1 shows the results together with the results of Example 1.

[0033]

[Table 1]

[0034]

According to the present invention, it is possible to rapidly produce a flame-retardant polyester having a high degree of polymerization without impairing the excellent physical properties of the polyester.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (1)

(57) [Claims] 1. A bifunctional organic phosphorus compound containing ethylene terephthalate units as a main component and having a phosphorus atom content of 500 p
pm or more, 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) has 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, which comprises solid-phase polymerization up to the point. Embedded image