KR930005143B1 - Process for the preparation of polyester - Google Patents

Abstract

The fire-retardant polyester is produced by (a) reacting a dimethyl terephthalate, an ethylene glycol, a cpd. of formula (I) as a fire retarding agent, an antimony trioxide, calcium acetate and cobalt acetate in the ester-exchange reactor, (b) reacting the reactant with cpds. of (II) and (III), (c) liquid-polymerizing the reactant with a phosphorous acid to obtain a polymer pellet having 0.4-0.45 intrinsic viscosity, (d) drying, heating the polymer pellet, and (e) solid-polymerizing it. In the formulas, Y=C1-10 hydrocarbon or sulfonyl; X=halogen; k=l=m=n=1-4; R1=R2=C1-5 alkene; R3=R4=C1-4 hydrocarbon; q=1-5; R5=C or C1-5 alkene; R6=R7=C1-6 alkyl. The polyester has a good thermal stability.

Description

Manufacturing method of flame retardant polyester with excellent thermal stability

The present invention relates to a method for producing a flame retardant polyester having excellent thermal stability. In general, polyester is excellent in mechanical properties, thermal properties, moldability, chemical resistance and is widely used as a fiber, film or plastic products. However, since polyester is composed of only three elements of carbon, hydrogen, and oxygen, it is easy to burn, and especially when used as a fiber, there is a high risk of fire. Recently, in order to prevent large fire accidents due to the large-scale building and compaction of buildings, flame-retardant polyesters are urgently required, and accordingly, fire-fighting regulations on synthetic fiber products are being tightened.

In the case of polyethylene terephthalate fiber, which is a main synthetic fiber, as a technique for imparting flame retardancy, a surface treatment method such as coating or impregnating a flame retardant on the surface of the fiber is used in the post-spinning process. Although the method of adding and mixing spinning and the like has been used, the post-polymerization post-treatment method as described above has economic advantages, but it is difficult to use due to problems such as deterioration in durability when repeated use. The direction that has been studied since then has been studied a technique of imparting flame retardancy to the yarn itself by copolymerizing or blending flame retardant materials during the polymerization process during polymerization.

As described above, the method of developing flame retardant polyester as a modification of the polymerization process itself is excellent in durability and flame retardant performance, and the physical property deterioration is less than that of the post-treatment method. Therefore, the development direction of the flame retardant polyester is mainly dependent on the pretreatment method. Among these methods, polyester has been reported to have the best method of copolymerizing flame retardant comonomer in the polymer chain.

As a specific example of the flame retardant method of the polyester fiber,

There is a method of adding flame retardant to the polymer by adding a halogen-containing flame retardant such as to the polymerization or spinning process, but since it is easy to thermally decompose the halogen compound at a high temperature, it has a great effect on the fiber properties and is effective because the halogen compound is used alone. In order to obtain flame retardancy, a large amount of flame retardant must be added, thereby easily causing fiber deterioration.

In addition, to improve this problem, a method of imparting flame retardancy to a polymer by using a phosphorus compound alone or by mixing a halogen compound and an antimony compound has been studied.

Flame retardants such as these are added to the polymerization process and randomly copolymerized in the polyester main chain or added to the spinning process to disperse them in polyester fibers. This results in excellent flame retardancy, but lacks compatibility with polyester fibers. In addition, there are various problems such as a decrease in viscosity, coloring, and workability of the polymer due to high treatment temperature, and the method of impregnation after spinning has a problem of deterioration in durability.

Therefore, the inventors of the present invention have repeatedly studied to solve or improve the problems of the conventional methods described above, thereby forming a copolymer by combining a flame retardant compound with a polyester chain, thereby improving the flame retardancy, thermal stability, and physical properties. The manufacturing method of the ester fiber was completed.

Hereinafter, the present invention will be described in detail.

The present invention is a compound selected from formulas (I) and (II) and compounds selected from formulas (III) and (IV) below in the preparation of general polyesters produced from ester-forming fluids of diols with dicarboxylic acids and dicarboxylic acids. Was added during the transesterification or polymerization reaction in the normal polyester manufacturing process, and polycondensed at a temperature of 280 ° C or lower, followed by liquid phase polymerization until reaching a degree of polymerization, followed by solid phase polymerization to prepare a flame retardant polyester fiber. It is characterized by.

(Wherein Y is a divalent hydrocarbon or sulfonyl group having 1-10 carbon atoms, X is a halogen element, k, l, m, n are each an integer of 1-4, R ₁ and R ₂ are each 1-5 carbon atoms) straight or branched alkene group)

(Wherein R ₃ and R ₄ are divalent hydrocarbon groups of 1-4 carbon atoms, q is an integer of 1-5, R ₅ is C or an Alkene group having 1-5 carbon atoms)

(Wherein R ₆ , R ₇ is an alkyl group having 1-6 carbon atoms)

(Wherein R ₈ and R ₉ are each an alkyl group having 1-6 carbon atoms)

The general formula (I) is the main component of the flame retardant of the present invention, and the general formulas (II), (III) and (IV) are auxiliary components, and the compound of the general formula (II) delays the aging of the polymer. It serves to prevent discoloration (especially sulfur change) of the polymer and when used in combination with a compound selected from general formula (III) or (IV), the thermal stability of the copolyester due to the flame retardant material is lowered and Coloring can be prevented. In order to minimize thermal decomposition of polymers and flame retardants during the polycondensation process, liquid phase polymerization is carried out up to a certain degree of polymerization, and then solid phase polymerization is performed at a temperature below the decomposition start temperature of the flame retardant to a desired degree of polymerization, thereby improving thermal stability, radioactivity and flame retardancy. It is possible to prevent the trimming phenomenon due to the flame retardant decomposition products in the copolymer generated when the solid phase polymerization does not occur, and at the same time easy to adjust the viscosity without accompanying thermal decomposition of the copolymer.

1-20% by weight, 0.05-1% by weight, more preferably 7-13% by weight, 0.1-0.3% by weight of the compounds of (I) and (II), respectively, were added to the polymer during the transesterification reaction. Copoly by the synergistic effect when the compound selected from III) or (IV) is added after the transesterification reaction at a ratio of 1: 0.2-1: 0.5, which is more preferably 1: 0.1-1: 1 In order to improve the thermal stability of the ester, and to increase the copolymerization ratio of the general formula (I), it is preferable to add a minimum amount at the beginning of the transesterification reaction. The reaction time of the compound of) with dicarboxylic acid and its ester-forming derivative can be best provided. When the compound is added, the initial stage of the transesterification reaction in the general formula (I) and the general formula (II) are added when the methanol outflow reaches 15-20% of the total flow rate. (III) and (IV) are preferably added immediately after the polycondensation reaction immediately after the ethylene glycol recovery step.

Liquid polymerization at the initial reaction temperature 140-235 ℃, late reaction temperature 240-280 ℃, vacuum 0.1-0.2mmHg in the same manner as described above when the 60-80% of the final final intrinsic viscosity of the desired liquid polymer When the viscosity reaches 0.4-0.5, it is made of pellets and dried, precrystallized at 180-220 ° C for 0.5-1.5 hours, and first heated at 170-190 ° C to make the moisture content less than 0.02% by weight. After heating at 235 ° C. for 2 hours to reach a solid phase polymerization temperature, the solid phase polymerization was performed at 200-230 ° C., followed by cooling with nitrogen gas at room temperature.

The intrinsic viscosity of the prepared flame retardant polyester polymer was measured in an ortho chloro phenol solution at 30 ° C., and the melting point and glass transition temperature were determined using a model 990 differential scanning thermal analyzer of DuPont, USA. The coloration degree of the copolymer was measured by using an automatic colorimetric colorimeter (ND-101 D type) and the L value (brightness) and b value (yellowness), and the polymer prepared for evaluating thermal stability was subjected to a rotary electric dryer (240). Heat treatment was performed to determine the heat resistance. The polyester polymer was stretched after spinning and evaluated for flame retardancy after being manufactured into a knitted fabric. The limit oxygen index (LOI) value was measured by a ductility gauge based on an oxygen coefficient based on ASTM D-2863-70, and the number of contact salts was JIS L-1092. Based on the D method, it evaluated by the 45 degree coil method by the micro burner, respectively. Radioactivity also indicated the number of rounds in the rounds per hour.

Hereinafter, the present invention will be described in detail with reference to Examples.

Example 1

6068 parts of dimethyl telephthalate, 1547 parts of ethylene glycol, 690 parts of flame retardant (I), 3.5 parts of antimony trioxide, 4 parts of calcium acetate, 0.3 parts of cobalt acetate were added to a transesterification reactor, and the mixture was heated and stirred. When (reactor internal temperature: about 190-200 ° C.), 7 parts of compound (II) and 2405 parts of ethylene glycol were added, and methanol was completely removed while gradually heating the reactor temperature to 230-235 ° C., and then compound (III) was removed. Compound (II) was slurried in an appropriate amount of ethylene glycol at a weight ratio of 1: 0.25 and charged into the reactor to complete the reaction. The product was transferred to a polymerization vessel, 3.4 parts of phosphorous acid was added thereto, and the liquid phase polymerization was completed under a reduced pressure of 0.1-0.2 mmHg so as not to exceed 280 ° C. to obtain a polymer having an intrinsic viscosity of 0.4-0.45. After drying the polymer pellets, they were pre-crystallized under nitrogen atmosphere at about 180 ° C, and heated under secondary heating when the moisture content was less than 0.02%. The polymer was formed by solid-phase polymerization at a temperature of 200-230 ° C. After the final polymer was prepared by cooling with nitrogen gas at room temperature, various tests were performed by spinning and stretching. The detailed results are shown in Table 1.

Example 2

The above various tests were carried out in the same manner as in Example 1 except that the ratio of Compound (III) to Compound (II) was 1: 0.5. The results are shown in Table 1.

Example 3

The above various tests were carried out in the same manner as in Example 1 except that Compound (IV) was replaced with Compound (II) in a weight ratio of 1: 0.2 in place of Compound (III). The results are shown in Table 1.

Example 4

The above various tests were carried out in the same manner as in Example 1 except that Compound (IV) was replaced with Compound (II) in a weight ratio of 1: 0.5 in place of Compound (III). The results are shown in Table 1.

Comparative Example 1

The above various tests were carried out in the same manner as in Example 1 except that Compounds (III) and (IV) were not added at all. The results are shown in Table 1.

Comparative Example 2

The above various tests were carried out in the same manner as in Example 1 except that 2 parts of Compound (III) was not added without any compound (III). The results are shown in Table 1.

Comparative Example 3

The above various tests were carried out in the same manner as in Example 1 except that 2 parts of Compound (IV) were not added without any compound (II). The results are shown in Table 1.

Comparative Example 4

The above various tests were carried out in the same manner as in Example 1 except that Compounds (II), (III), and (IV) were not added at all. The results are shown in Table 1.

Comparative Example 5

The various tests were carried out in the same manner as in Example 1 except that the reaction was completed by liquid phase polymerization without performing solid phase polymerization. The results are shown in Table 1.

Comparative Example 6

3740 parts of ethylene glycol was added at the beginning of the transesterification reaction, except that the compounds (I), (II), (III), (IV) and cobalt acetate were not added at all, and were subjected to a regular PET production method without solid phase polymerization. After the same, the above various tests were performed. The results are shown in Table 1.

As can be seen from Table 1, in the case of Examples, the defects such as intrinsic viscosity decrease are the least, and the radioactivity, color thermal stability, and flame retardancy are most excellent in comparison with Comparative Example 6, which is a normal PET manufacturing method.

TABLE 1

Claims (3)

When preparing a polyester produced by the reaction of diol with dicarboxylic acid or ester thereof, when preparing a flame retardant polyester by copolymerizing a compound of the following general formula (I), the following general formulas (II), (III) and (IV) A method for producing a flame-retardant polyester having excellent thermal stability, characterized in that the solid-phase polymerization of the compound represented by the formula and 60-80% of the final intrinsic viscosity as the initial intrinsic viscosity.

(Wherein Y is a divalent hydrocarbon or sulfonyl group having 1-10 carbon atoms, X is a halogen element, k, l, m, n are each an integer of 1-4, R ₁ and R ₂ are each 1-5 carbon atoms) straight or branched alkene group).

(Wherein R ₃ and R ₄ are divalent hydrocarbon groups of 1-4 carbon atoms, q is an integer of 1-5, R ₅ is C or an Alkene group having 1-5 carbon atoms)

(Wherein R ₆ , R ₇ is an alkyl group having 1-6 carbon atoms)

(Wherein R ₈ and R ₉ are each an alkyl group having 1-6 carbon atoms) The flame-retardant poly with excellent thermal stability according to claim 1, wherein the compounds of general formulas (I) and (II) are added in an amount of 1-20% by weight and 0.05-1% by weight with respect to the final polymer during the transesterification reaction. Process for preparing esters. 2. The heat according to claim 1, wherein the compound of formula (III) or (VI) is added immediately after the ethylene glycol recovery process with a weight ratio of 1: 0.1-1: 1. Method for producing a flame retardant polyester with excellent stability.