KR940003878B1 - Forming method of polyester - Google Patents

Abstract

Polyester is prepd. by reaction of dicarbon acid contg. terephthalic acid as main component and glycol contg. ethylene glycol as main component. In the process, the ethylene glycol ester and its lower polymeric polymer to be obtained in the step of esterification of the dicarbon acid with glycol, are satisfied in the condition of the formula (I) and (II); Φ = HV/(AV+HV) >= 0.85 (I), δ = (SV-AV)/SV >= 0.97 (II), where AV is the amt. of carboxyl terminal gp. in dry olygomer, HV is the amt. of hydroxyl terminal gp. in dry oligomer (eq/kg) and SV is gum value of dry oligomer. The polyester contains lower than 0.5% of the lower polymer of polymerization degree lower than 10.

Description

Production method of polyester

The present invention relates to a method for producing polyester, in particular, a method for producing polyester having improved operability.

Polyester, especially polyethylene terephthalate, has excellent mechanical, physical, and chemical performances, and thus is widely used as a molding material for fibers, films, and the like. Among polyesters, terephthalic acid is the main component, and ethylene glycol, tetramethylene glycol, It is particularly important to have hexamethylene glycol or dichlorohexane-1 and 4-dimethylol as main components.

Polyethylene terephthalate is directly esterified terephthalic acid and ethylene glycol at 150 to 270 ℃, pressurized or lower alkyl ester and terephthalic acid glycol ester of terephthalic acid and its low polymer (130) After producing BHT), it is prepared by removing the glycol generated by heating at a temperature above the melting point under reduced pressure, and then polycondensing it to an appropriate degree of polymerization. The polyester thus obtained is extruded in the form of fibers or films into the microporous spinneret or the slits in the molten state, and then stretched and commercialized.

However, melt spinning the polyester in a conventional manner causes bending of the polymer flow on the surface of the spinneret within a short time after the start of spinning (hereinafter referred to as curvature), which causes lapping during spinning and stretching. It will drastically reduce the spinning operation. If the curvature worsens, the wiping of the surface of the detention surface with a release agent such as silicon is radiated again, but the curvature soon appears again. If the occurrence of the curvature is severe, frequent exchange of spinnerets is required, and not only the impairment of the operation but also the non-uniformity of the yarn.

As a method for solving such a disadvantage in the related art, a method of increasing the amount of phosphorus compound used as a stabilizer (Japanese Patent Laid-Open No. 49-7400), or a method of adding monocarboxylic acid or its ester-forming derivative (Japanese Patent Laid-Open No. 50-97691) ), A method of adding terephthalic acid (Japanese Patent Laid-Open No. 50-82197), a method of adding an acid phosphate or an acid phosphate of an alkali metal or an alkaline earth metal (Japanese Patent Laid-Open No. 50-87147), an aromatic polyvalent carboxylic acid or an anhydride thereof The method of adding (Japanese Unexamined-Japanese-Patent No. 60-34569) etc. are proposed. However, such a method does not sufficiently solve the above-mentioned drawbacks, and because it uses additives other than a catalyst, it is not a good process or economically. The polyester thus obtained deteriorates its physical properties. It is not suitable to solve the disadvantage.

The present inventors have closely examined the curvature phenomena generated during the melt spinning of the polyester in order to solve the above-mentioned disadvantages, and as a result, there is a close relationship between the foreign matter (hereinafter referred to as the spherical foreign material) attached to the spinneret and the curvature phenomenon. It was found that curbing phenomenon can be prevented by suppressing the adhesion trace of the foreign material of the surface. On the other hand, as a result of analyzing the foreign material of the surface, the low polymer (n≤10) of polyester, the antimony as a catalyst, and the phosphorus compound as a heat stabilizer form a complex with each other, and are adhered to the surface by the insoluble insoluble adhesive material. I knew that it caused.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly focused on reducing the oligomer of polyester which becomes a source of a complex, and came to this invention as a result of earnestly examining. That is, the present invention is to prepare a polyester by reacting dicarboxylic acid having a terephthalic acid as a main component and glycol having a ethylene glycol as a main component, and ethylene glycol ester obtained in the step of directly esterifying the dicarboxylic acid and ethylene glycol. It is a method for producing a polyester, characterized in that the oligomer to satisfy the conditions of the following formula (I), (II).

ψ = HV / (AV + HV) ≥0.85 (I)

δ = (SV-AV) /SV≥0.97 (II)

However, AV: carboxyl terminal content in dry oligomers (eq / kg), HV: hydroxyl terminal content in dry oligomers (eq / kg), SV: dry oligoma saponifier (eq / kg)

The present invention also relates to a method for producing a polyester, wherein the content of the oligomer having a degree of polymerization of 10 or less when the above-mentioned ethylene glycol ester and its oligomer is polycondensed is 0.5% or less with respect to the final polyester. .

As bifunctional aromatic carboxylic acid used by the method of this invention, terephthalic acid is a main component and ethylene glycol is a main component as glycol. As a method for producing a glycol ester and its oligomer from such an acid component and a glycol component, for example, ethylene glycol ester of terephthalic acid, which is a member of polyethylene terephthalate, and the oligomer thereof are esters of terephthalic acid and ethylene glycol directly. Although a general method of reacting or transesterifying lower alkyl esterified ethylene glycol of terephthalic acid may be employed, the present invention mainly deals with direct esterification. The adoption of the direct esterification method is rapidly increasing than the transesterification reaction with the industrial production of TPA (terephthalic acid), and the ethylene glycol ester and its oligomer after the direct esterification reaction have a degree of polymerization of 2 to 10. Known.

Specifically, in the present invention, the value of δ (esterification rate) in the properties of the ethylene glycol ester and its oligomer after the direct esterification reaction should be 0.97 or more, and Roxy terminal content rate) is 0.85 or more to fully exhibit the effects of the present invention. When the δ value is 0.97 or less, the content of unreacted TPA in the ethylene glycol ester and its oligomer is increased to increase the content of the oligomer having a polymerization degree of 10 or less in the final polymer. It causes trouble. In addition, when the value is 0.85 or less, the compound having a melting point of ethylene glycol ester and the polymer higher than the reaction temperature (above 300 ° C) is contained, and thus the substance is degraded to remain in the final polymer, and sublimable. This makes it difficult to control the polymerization operation and conditions. In addition, the content of the carboxyl terminal group is increased to increase the complexing ability of the catalyst and the heat stabilizer, antimony (Sb), phosphorus (P), as well as to form a complex with Sb / P, so that a large amount of foreign matter is generated in the surface of the debris. In case of polycondensation under high temperature and high vacuum, a large amount of sublimation material is generated and the vacuum line and EG recovery pipe in the polycondensation reactor are clogged, which may interfere with the operation. .

In addition, when polycondensation is carried out using oligomers other than these conditions, the content of oligomers having a degree of polymerization of 10 or less in the final polyester is 0.5% or more, and a large amount of insoluble insoluble adhesive materials are generated during melt spinning. In addition to this, the wiping cycle is shortened, which greatly affects the operability. In other words, the ethylene glycol ester as the esterification product and the oligomer thereof have a δ value of 0.97 or more and a ψ value of 0.85 or more, so that the content of the oligomer having a polymerization degree of 10 or less in the final polyester can be controlled to 05% or less. It can reduce the insoluble insoluble foreign matter of the surface of the mold and prevent the curvature phenomenon during melt spinning, it is possible to produce a uniform high purity polyester.

When melt spinning the polyester obtained by the method of the present invention, the amount of foreign matter adhering to the spinneret adheres and the amount of lamination is extremely small, and the time for the occurrence of curvature is remarkably prolonged. The enemy effect is remarkable. In addition, the spinning conditions and the post-spinning process conditions were remarkably improved, and the polymerization conditions were remarkably stable.

In carrying out the present invention, it is preferable to appropriately control the pressure and temperature of the direct esterification reaction, the pressure and temperature of the polycondensation reaction within the range not departing from the object of the present invention, and if necessary, add an additive for a specific purpose. You may also do it.

Hereinafter, the present invention will be described in more detail with reference to the following examples.

The part in an Example is a weight part, (eta) is an intrinsic viscosity calculated | required by the value measured at 30 degreeC in the orthochlorophenol solution. The HV value is 0.5 g dry oligoma sample heated with acetylating reagent (pyridine solution of acetic anhydride) at 95 ° C. for 90 minutes and then hydrolyzed with excess acetic anhydride to remove acetic acid produced by the reaction. It is appropriate value with 0.2N NaOH aqueous solution. AV value is 0.5g dry oligomer is dissolved in warm pyridine, the solution is cooled to room temperature and then titrated with 0.2N NaOH aqueous solution. SV value is 0.5g dry oligoma is dissolved by heating in 20ml EG, 25ml 0.5N NaOH aqueous solution is added, heated for 90 minutes, and titrated with 0.5N HCl aqueous solution. The radioactive properties of the foreign matters and curvature phenomena around the spinnerets were obtained when melt spinning was carried out using a spinneret having 30 spinnerets having a diameter of 0.25 mm for 7 days at a discharge rate of 80 g / min and a discharge temperature of 285 ° C for a winding speed of 1,200 m / min. The stretchability was expressed as a generated state, and the stretchability was expressed as an operation rate generated when winding the 150 f / 30d and 25 kg by stretching the undrawn yarn obtained at the above conditions at a draw temperature of 85 ° C., a draw ratio of 3.5 times and a drawing speed of 1100 m / min. The degree of polymerization is calculated by dividing the value obtained by dividing with GPC divided by the total sample. Continuous spinning time is the maximum time that spinning is possible without cutting.

Example 1

100 parts of terephthalic acid, 45 parts of ethylene glycol, and 0.3 parts of tetraethyl hydroxyammonium (TEH) were added to a 150 ° C reaction tube containing a molten BHT (ethylene glycol ester and its oligomer), which had been prepared, and then 260 ° C 1.7kg / ㎠ After the reaction was conducted under pressure, the reaction was carried out to 90% of the flow rate of water, and slowly discharged for about 2 hours to obtain BHT having δ = 0.98 and ψ = 0.95, followed by 0.03 part of antimony trioxide as a polymerization catalyst and phosphoric acid as a heat stabilizer. After adding 0.015 parts and 0.4 parts of titanium dioxide as an anti-inflammatory agent, the ethylene glycol slurry was added, and the temperature was raised to 290 ° C and polycondensation reaction was carried out under reduced pressure of 1 mmHg or less for 4 hours to obtain polyethylene terephthalate having? In the polyester, low polymerization degree PET having n <10 was 0.18%. The physical properties when the polymer was spun are shown in Table 1. No curvature was found during the 7 days spinning period, the radioactivity was extremely good, and the continuous spinning time was 104 hours. After 7 days, the height of the surface of the foreign material was about 7 µm, and the average lap ratio at the time of stretching was 0.2%, and the stretchability was extremely good.

Example 2

Prepared in the same manner as in Example 1 except that δ = 0.97, ψ = 0.95, η = 0.653, melting point 260.3 ℃ and low-polymerization PET is produced 0.23% polyester, the physical properties of the spinning is shown in Table 1 .

Example 3

Prepared in the same manner as in Example 1 except that δ = 0.99, ψ = 0.95, η = 0.665, melting point 260.1 ℃, and low-polymerization PET is produced 0.23% polyester, the physical properties of the spinning is shown in Table 1 .

Example 4

Prepared in the same manner as in Example 1 except that δ = 0.99, ψ = 0.87, η = 0.651, melting point 260.0 ℃ and low-polymerization PET is produced 0.27% polyester, the physical properties of the spinning is shown in Table 1 .

Example 5

Prepared in the same manner as in Example 1 except that δ = 0.99, ψ = 0.97, η = 0.65, melting point 260.1 ℃ and a low-polymerization PET is produced 0.15% polyester, the physical properties of the spinning is shown in Table 1 .

Example 6

Prepared in the same manner as in Example 1 except that δ = 0.97, ψ = 0.97, η = 0.649, melting point 260.2 ℃, low-polymerization PET is produced 0.15% polyester, and the physical properties when spinning it is shown in Table 1 .

Example 7

Prepared in the same manner as in Example 1 except that δ = 0.95, ψ = 0.11, η = 0.653, melting point 260.1 ℃ and a low-polymerization PET of 0.18% to prepare a polyester, the physical properties of the spinning is shown in Table 1 .

Comparative Example 1

Prepared in the same manner as in Example 1 except that δ = 0.95, ψ = 0.71 with η = 0.651, melting point 259.8 ° C., and low-polymerization PET having 2.5% of polyester. .

Comparative Example 2

Prepared in the same manner as in Example 1 except that δ = 0.69, ψ = 0.55, η = 0.65, melting point 260.0 ℃ and low-polymerization PET is produced 5.7% of polyester, and the physical properties when spinning it is shown in Table 1 .

Comparative Example 3

Prepared in the same manner as in Example 1, except that δ = 0.97, ψ = 0.82, η = 0.88, melting point 259.9 ℃, low-polymerization PET was produced 2.0% polyester, and the physical properties when spinning it is shown in Table 1 .

[Comparative Example 4]

Prepared in the same manner as in Example 1 except that δ = 0.85, ψ = 0.32 with η = 0.645, melting point 259.7 ° C. and low-polymerization PET of 7.0%, and the physical properties of the spinning were shown in Table 1. .

TABLE 1

* Xn≤10 (%): fraction of oligomer with a degree of polymerization of 10 or less, curvature point: the point of occurrence of the first wave (days) (×: not found for 7 days)

Claims (2)

In preparing polyesters by reacting thicarboxylic acid having terephthalic acid as a main component and glycol having ethylene glycol as its main component, the ethylene glycol esterified oligomer obtained in the step of directly esterifying dicarboxylic acid and glycol Method for producing a polyester, characterized in that to satisfy the conditions of the following formula (I), (II). ψ = HV / (AV + HV) ≥0.85 (I) δ = (SV-AV) /SV≥0.97 (II) However, AV: carboxyl end content in dry oligoma (eq / kg), HV: hydroxyl end content in dry oligoma (eq / kg), SV: dry oligoma saponifier (eq / kg) The method for producing a polyester according to claim 1, wherein the content of the oligomer having a degree of polymerization of 10 or less is 0.5% or less with respect to the final polyester when the ethylene glycol esterified oligomer is subsequently subjected to polycondensation.