JPS6383126A - Production of polyester - Google Patents

Abstract

PURPOSE:To produce a polyester excellent in hue and heat stability, by polycondensing an ester of an alkylene glycol with a terephthalic acid-based dicarboxylic acid and/or a precondensate of said ester in the presence of a niobic acid. CONSTITUTION:A polycondensation catalyst is obtained by heating niobic acid, obtained by subjecting a niobate to alkali fusion, extracting the product with hot water, acidifying the obtained aqueous solution with a strong acid, separating and water-washing the formed precipitate, to 80-400 deg.C. An ester of an alkylene glycol with a dicarboxylic acid containing at least 80mol% terephthalic acid and/or a precondensate of said ester is polycondensed at 250-290 deg.C in the presence of 0.001-0.2wt%, based on the acid component of the polyester, said polycondensation catalyst.

Description

[Detailed description of the invention] (Industrial applications are surprising) The present invention relates to a method for producing polyester, and in particular, a method for producing polyester with a high degree of polymerization in a short time using a novel and highly effective reaction catalyst. be.

(Prior art) Among the polyesters produced industrially today, the most important are polyalkylene terephthalates, represented by polyethylene terephthalate, which are widely used in fabrics, fibers, films, and other molded products. . Polyalkylene terephthalate is usually obtained by a two-step reaction, the first step being heating to 160-240°C in the presence of dimethyl terephthalate and alkylene glycol tracatalyst to remove the generated methanol and carrying out the transesterification reaction. Alternatively, terephthalic acid is directly esterified with alkylene glycol, and the second stage reaction is polycondensation. In this case, the polycondensation is carried out under reduced pressure at a temperature of 260°C or higher, which is higher than the melting point of polyalkylene terephthalate, or the initial polymer is once cooled and solidified, pulverized into powder or pieces of an appropriate size, and then the polycondensation is carried out under reduced pressure. Solid phase polymerization is carried out at a temperature below the melting point of alkylene terephthalate under reduced pressure or in an inert gas flow. Catalysts are generally used to facilitate these reactions, and it is known that not only the speed but also the color tone and thermal stability of the polyester are greatly influenced by the type of catalyst used.

Therefore, it is extremely important to provide a catalyst that provides suitable performance, ie, a polyester with a fast reaction rate, good color tone, and excellent thermal stability. A number of polycondensation catalysts suitable for the production of have been proposed.

Regarding niobium and niobium compounds, a method using 12-obium metal as an m-condensation catalyst (Japanese Patent Publication No. 47-8
225), a method using a complete hydrolysis product of niobium pentahalide as a 1i condensation catalyst (Japanese Patent Publication No. 1973-
40810), transesterification of niobium compounds, m
Method of using it as a condensation catalyst (Japanese Patent Publication No. 88-15498
Publication), aromatic oxide of niobium! ! There are a method of using it as an m-condensation catalyst (Japanese Patent Publication No. 12158/1982), a method of coexisting a small amount of an alkylene glycol-soluble niobium compound with another polycondensation catalyst (Japanese Patent Application Laid-open No. 20027/1983).

(Problems to be Solved by the Invention) However, when these conventional niobium catalysts were examined in detail, they were not satisfactory in terms of reaction promotion effect and solubility of the catalyst in the reaction system. The present invention was completed as a result of repeated research in search of an even better polycondensation catalyst.

An object of the present invention is to provide a method for extremely rapidly producing a highly polymerized polyester having a good hue and good thermal stability.

(Means for Solving the Problems) The method of the present invention is used as a polymerization catalyst when polycondensing esters of dicarboxylic acids, mainly terephthalic acid, with alkylene glycol and/or their initial condensates to produce polyesters. It is characterized by using niobic acid that has been heat-treated at a temperature in the range of 80°C to 40.0°C.

As the niobium catalyst used in the present invention, for example, a known method described in New Edition Inorganic Chemistry, authored by Toshi Chiya, published by Sangyo Tosho ■, 1972. That is, it is obtained by melting niobate with an alkali, extracting it with hot water, adding a strong acid such as sulfuric acid to the aqueous solution to make it acidic, and separating the precipitate and washing it with water.

Niobic acid heated at a temperature in the range of 80° C. to 400° C. significantly accelerates the reaction rate and can be used as an effective polycondensation catalyst. The processing temperature is particularly 100°C to 8°C.
00°C is desirable. At temperatures below 80°C, the reaction promoting effect is insufficient, and at temperatures above 400°C, the catalyst becomes difficult to dissolve in the reaction system and the reaction promoting effect becomes insufficient.

When heat-treating niobic acid, it is preferable to do so under an atmosphere of inert gas or under reduced pressure. Although the cause is unknown, niobic acid may change color and denature in the air.

The reason why the heat-treated niobic acid of the present invention exhibits a significantly high reaction promoting effect is not clear, but the literature (surface vol.
2B (1985), P89-49), such niobic acid heated at low temperature is Eg.

Many acid sites with strong acidity of ≦-5,6 (corresponding to the acid strength of 70% H2804) are generated, and it is thought that these function as active sites for the polycondensation reaction.
Since the niobic acid catalyst of the present invention is uniformly dispersed in the polymer and the resulting polymer is transparent, the chemical formula *b2o5・
It can also be explained that several hydrates of niobium oxide represented by XH2O are polymerized to form isopolyic acid, which preserves its unique structure in the polymer and exhibits a reaction promoting effect due to this.

The conditions for the double bond reaction may be the usual ones, and the reaction temperature is 25°C.
0 to 290°C is preferred.

The amount of the catalyst used in the present invention varies depending on the reaction conditions, but in general, the amount of the catalyst used is o
, oot~0.2 mold part%, preferably 0.005~0.
06% by weight. Further, the catalyst of the present invention is preferably added after the transesterification reaction or esterification reaction or during the polycondensation reaction, but it may be added beforehand.

Furthermore, the method of the present invention may be used in combination with known catalysts based on antimony, germanium, or titanium, or with known stabilizers such as phosphorus compounds, or with pigments such as titanium oxide or antistatic shavings. .

The method of the present invention is effectively applied to the production of polyesters consisting of dicarboxylic acids, mainly terephthalic acid, and alkylene glycols, but typical glycols in this case are ethylene glycol and 1,4-butane. The present invention is also applied to the production of a copolyester containing a diol, the above-mentioned terephthalic acid, and at least one eighth component other than glycol. Copolymerization components include inphthalic acid, P-βoxyethoxybenzoic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, adipic acid, cepatic acid, 5-sodium sulfoisophthalic acid, 1,4-butanediol. Propylene glycol, triethylene glycol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexane dimetatool, 1,
Known compounds used for modifying polyesters include 4-bisoxyethoxybenzene, bisphenols, polyethylene glycol, and the like.

(Effects of the Invention) As described above, in the present invention, the polyester polycondensation reaction time is significantly shortened compared to conventional methods, and the obtained polyester has an extremely excellent hue.

(Examples) Next, examples of the present invention will be described, but the present invention is not limited to these examples. In the examples, "parts" are parts by weight, and intrinsic viscosity is a value measured at 20° C. using phenol:tetofchloroethane (60:40) as a solvent.

Example 1 Pfujil's C! BMM (Companhia Bra
si-1eira de Metalurgla e
Add 10 parts of niobic acid (Mineracao) to 5 parts of pure water.
After washing twice, the catalyst was heated at 100° C. for 16 hours and used as a catalyst.

Put 100 parts of terephthalic acid and 45 parts of ethylene glycol into a rectifier and a reactor equipped with a stirrer, and add 2U of nitrogen gas.
/CmG and heat to 250℃ for about 2 hours while stirring thoroughly.
The temperature was raised over a period of time, and the mixture was heated as it was, and by-product water was successively extracted from the system through a rectification column. When the distilled water amounted to 20 parts, the first stage reaction was completed.

Next, this reaction product was transferred to a reactor with an inner volume of aoomz under reduced pressure and equipped with a stirrer, and 0.08 part of the above catalyst was added thereto. The reactor was heated to 280°C and immersed in a chair, and after 10 minutes, the pressure was gradually reduced and maintained at 1 mmH, F or less to 0.7
The reaction was allowed to proceed for 5 hours. The resulting polymer was extruded through the bottom nozzle of the reactor into cold water to quench the polymer. The intrinsic viscosity of this polymer was 0.751, and the appearance was pale yellow and transparent.

Examples 2 to 4, Comparative Examples 1 to 4 The results are shown in Table 1 in the same manner as in Example 1, except that niobic acid further heat-treated in a nitrogen stream at a predetermined temperature for 2 hours was used as a catalyst. Table 1 also shows the results of comparative examples using commercially available niobium pentachloride and niobium oxide as catalysts.

Table 1 Examples 5 to 9 Table #g2 shows the results in the same manner as in Example 1 except that the addition certificate of the niobic acid catalyst was changed.

Table 2 Examples 10-12 Commercially available niobium chloride (NbOlg, purity 95%) was added to 10 parts of water.
) and 5 parts of various hydrolyzing agents (alkali),
Upon stirring, it became a white colloidal solution. To this, IN
Hydrochloric acid was gradually added dropwise to adjust the pH to 1, and the resulting precipitate was separated with a decantation cylinder and washed repeatedly with pure water. When the drained liquid became neutral, the precipitate was washed with too'c for 2 hours. Heat treated for hours. Using this as a catalyst, polycondensation was carried out in the same manner as in Example 1. The results are shown in Table 8.

Table 8 Example 18 100 parts of terephthalic acid, 92 parts of 1,4-butanediol, and 0.01 part of the niobic acid from Example 1 were charged into a reactor equipped with a rectification column, and the water produced at 220°C was After distillation, the esterification reaction was carried out for 98 hours, and the amount of water distilled out was 166 parts.

Next, this reaction product was transferred to a polybond reactor, and the pressure was reduced while increasing the temperature to 250°C, and l x nmH! The polycondensation reaction was carried out for 1 hour while stirring under reduced pressure below i.

The obtained polymer had an intrinsic viscosity of 0.85, and the Appearance Procedural Amendment Form August a, 1985, Commissioner of the Patent Office, Kuro 1) Akira Yu jIl! 2 H1. Indication of the case 1986 Patent Application No. 228819 2 Name of the invention Method for producing polyester 3 Person making the amendment Relationship to the case Representative applicant Address 171 Part 4, Sumida 5-chome, Sumida-ku, Tokyo Name (09
5) flbo Co., Ltd. 1-5-90, Tomobuchi-cho, Bejima-ku, Osaka 534, Kanebo Co., Ltd. Patent Department 6, ``Detailed Description of the Invention'' of the specification to be amended - 7, Details of the contents of the amendment The description in the book is corrected as follows.

that's all

Claims (2)

[Claims] (1) When producing polyester by polycondensing esters of dicarboxylic acids, mainly terephthalic acid, with alkylene glycols and/or their initial condensates, heating is performed at a temperature in the range of 80°C to 400°C as a polycondensation catalyst. A method for producing polyester, characterized by using treated niobic acid. (2) The method according to claim 1, wherein 80 mol % or more of the dicarboxylic acid mainly consisting of terephthalic acid is terephthalic acid.