Catalyst solution and preparation method thereof, polyester composition and preparation method and application thereof

Abstract

The invention discloses a catalyst solution and a preparation method thereof, a polyester composition and a preparation method and application thereof. The catalyst solution contains a germanium-based catalyst and an alkali metal compound and / or an alkaline earth metal compound, and the molar ratio of the germanium element to the sum of the alkali metal element and the alkaline earth metal element is 0.02-4.00. The polyester composition prepared from the catalyst solution contains germanium and alkali metal elements and / or alkaline earth metal elements, and the molar ratio of the germanium to the sum of the alkali metal elements and the alkaline earth metal elements is 4.00 or below. The polyester composition is low in linear oligomer content, excellent in hue and heat resistance and applicable to fibers, films, engineering plastics and the like.

Description

Technical Field

[0001] The present invention relates to a catalyst solution and a polyester composition prepared under the catalytic action of the catalyst solution, and specifically, to a catalyst solution containing a germanium-based catalyst and an alkali metal compound and / or an alkaline earth metal compound. The polyester composition prepared by the catalyst solution has a low content of oligomers, good heat resistance, less gel and less foreign matter. Background Art

[0002] At present, the synthesis catalyst of polyester is mainly antimony catalysts such as ethylene glycol antimony, antimony trioxide, and antimony acetate. Antimony catalysts have high activity, but are easily reduced to metallic antimony, resulting in a decrease in product color. Some catalysts precipitate and agglomerate, contaminating spinning filters, components and spinnerets, or easily generating foreign matter in the film manufacturing process, which also has a bad effect on the performance of polyester fibers and films.

[0003] Titanium catalysts have high catalytic activity and low dosage. They have been widely used at home and abroad and are considered to be the most likely products to replace antimony catalysts. However, titanium catalysts have high catalytic activity for polycondensation side reactions, so the prepared polyester has poor heat resistance, is easy to generate gel, and has severe yellowing, which seriously restricts the application of titanium catalysts.

[0004] Germanium catalysts do not contain heavy metals, are basically pollution-free to spinning components, and have catalytic activity second only to antimony, titanium and other catalysts. The resulting polyester composition has good color tone and heat resistance, and is recognized as being able to replace antimony and titanium catalysts. Japanese Patent Laid-Open No. 2015-86317 discloses a method for preparing a polyester composition, wherein terephthalic acid or terephthalate and diol are subjected to an esterification reaction or an ester exchange reaction, followed by a polycondensation reaction, and alkali metal phosphate, phosphoric acid and catalyst germanium dioxide and co-catalyst manganese acetate are added to the reaction to obtain a polyester composition with a low oligomer content. However, in this patent, the catalyst germanium dioxide is added directly, and this addition method will result in poor dispersibility of germanium dioxide in the polyester reaction system, reduced catalytic activity, prolonged polymerization reaction time, and increased foreign matter content in the polyester. In addition, the steps of the technical solution of this patent also include solid phase polymerization engineering and hot water treatment deactivation engineering, and the reaction cost will be relatively high. In addition, the resources of germanium compounds are very scarce and expensive. If a large amount of germanium compounds are added to improve catalytic activity, the cost of polyester will also increase. Summary of the invention

[0005] The object of the present invention is to provide a germanium-based catalyst solution and a polyester composition having excellent color tone and heat resistance obtained by using the solution as a catalyst. The polyester composition can be used for fibers, films, engineering plastics, etc.

[0006] The technical solution of the present invention:

[0007] A catalyst solution containing a germanium-based catalyst, an alkali metal compound, and / or an alkaline earth metal compound, wherein the molar ratio of germanium element to the sum of alkali metal elements and alkaline earth metal elements is 0.02 to 4.00.

[0008] The catalyst solution is prepared by the following method: first, the alkali metal compound and / or the alkaline earth metal compound are pre-dispersed in ultrapure water to obtain a pre-dispersed solution, then the germanium-based catalyst is added to the pre-dispersed solution, and stirred until it is completely transparent and clear, and finally a diol is added to obtain the catalyst solution; when adding, the molar ratio of germanium element in the germanium-based catalyst to the sum of alkali metal elements in the alkali metal compound and alkaline earth metal elements in the alkaline earth metal compound is 0.02 to 4.00.

[0009] The present invention also discloses a polyester composition prepared using the above solution as a catalyst. The polyester composition is mainly obtained by reacting an aromatic dicarboxylic acid or its esterification derivative and an aliphatic diol in the presence of the catalyst solution. The polyester composition contains germanium element, an alkali metal element, and / or an alkaline earth metal element, and the molar ratio of the germanium element to the sum of the alkali metal element and the alkaline earth metal element is below 4.00.

[0010] The content of linear oligomers in the polyester composition is preferably below 100 ppm.

[0011] The alkali metal element is preferably selected from one or more of lithium, sodium, potassium, and cesium, and the alkaline earth metal element is preferably selected from one or more of magnesium, calcium, and barium.

[0012] The content of germanium element in the polyester composition is preferably equivalent to 1.0 to 200.0 ppm of the total amount of the polyester composition.

[0013] The content of phosphorus element in the polyester composition is preferably equivalent to 1.0 to 230.0 ppm of the total amount of the polyester composition.

[0014] The total amount of alkali metal element and alkaline earth metal element in the polyester composition is preferably equivalent to 300 ppm or less of the polyester composition.

[0015] The heat resistance index %BB of the polyester composition after heat treatment at 290 °C for 6 hours under nitrogen is preferably 0.55 or less; the gel rate of the polyester composition after heat treatment at 300 °C for 6 hours in a mixed gas of nitrogen and oxygen with an oxygen concentration of 1 vol% is preferably 10.0 wt% or less; the haze value of the polyester composition is preferably 5.00% or less.

[0016] The present invention also discloses a method for preparing the above polyester composition, which mainly involves obtaining an oligomer by esterification or transesterification of an aromatic dicarboxylic acid or its esterification derivative with an aliphatic diol, and then obtaining the polyester composition by polycondensing the oligomer. The catalyst solution is added during the polyester reaction.

[0017] The addition amount of the catalyst solution, calculated based on the germanium element therein, is preferably equivalent to 2.0 - 400.0 ppm of the polyester composition.

[0018] During the polyester reaction, a phosphorus compound equivalent to 1.0 - 300.0 ppm of the total amount of the polyester composition in terms of phosphorus element is preferably added.

[0019] In the present invention, a germanium-based catalyst is first configured into a transparent solution with good dispersibility to improve the dispersion and catalytic efficiency of the germanium-based catalyst in the polyester reaction, and a polyester composition with a low content of linear oligomers, good hue and heat resistance, low gel formation amount and few foreign substances, and suitable for fields such as fibers, films, and engineering plastics is obtained. Detailed implementation mode

[0020] Currently, common antimony catalysts have problems such as reducing the color of the polyester composition, contaminating the spinning pack, and generating foreign substances during the film-making process, and their application as polyester catalysts is increasingly restricted. Titanium-based catalysts, as environmentally friendly catalysts with high catalytic activity, are widely used. However, titanate catalysts have a relatively high catalytic activity for polycondensation side reactions, so the polyester prepared has a relatively serious yellowing phenomenon, and the heat resistance and hydrolysis resistance of the polyester are also poor.

[0021] Germanium catalysts have good catalytic activity, are basically non-polluting to the spinning pack, and the obtained polyester composition has good hue and heat resistance, so they can be used to replace titanium-based catalysts.

[0022] When adding germanium-based catalysts to a polyester reaction, generally, a slurry is prepared by mixing the germanium-based catalyst and a diol solution, and then added to the polyester reaction system. However, since germanium-based catalysts are insoluble in diols, the dispersibility of germanium-based catalysts in the slurry is not good. The germanium-based catalysts added in this way also have poor dispersibility in the polyester reaction system, are prone to agglomeration, and have relatively low catalytic efficiency. A large amount of germanium-based catalysts need to be added to obtain a polyester composition with a target range of viscosity (IV) within a specified time, increasing the cost. Moreover, since germanium-based catalysts do not react with polyester end groups and exist in a free state in the polyester reaction system, they are easily extracted together with diols during the extraction of diols from the polyester reaction system, increasing the impurities in the recovered diols and affecting the reuse of the recovered diols. At the same time, because germanium-based catalysts exist in a free state in the polyester, they are also regarded as foreign substances relative to the polyester composition. Therefore, if a large amount is added to obtain good catalytic activity, it will also lead to an increase in the content of foreign substances in the polyester, a higher gel rate of the obtained polyester composition, and a higher haze of the film made from the polyester composition.

[0023] In the present invention, a mixed solution of a germanium-based catalyst and an alkali metal compound and / or an alkaline earth metal compound is first prepared in a diol, so that the germanium-based catalyst forms a germanate with the alkali metal compound and the alkaline earth metal compound, thereby improving the solubility and dispersibility of the germanium-based catalyst in the diol. Adding the prepared catalyst solution to the polyester reaction system also improves the dispersibility of the germanium-based catalyst in the polyester reaction system, making the catalytic activity of the germanium-based catalyst higher than that added by the conventional method, with a fast polymerization reaction rate, a relatively low content of linear oligomers in the obtained polyester composition, good heat resistance of the polyester composition, and a low gel rate. At the same time, by preparing and adding the catalyst solution of the present invention, since the catalytic activity of the germanium-based catalyst is improved, compared with the conventional addition method, the amount of the germanium-based catalyst can be appropriately reduced to achieve the same catalytic effect, thus achieving the purpose of cost reduction and reducing the content of foreign substance free germanium-based catalysts in the polyester composition. At the same time, improving the dispersion of the germanium-based catalyst in the polyester reaction can also reduce its agglomeration, thereby further achieving the purpose of reducing foreign substances.

[0024] The linear oligomers described in the present invention mainly refer to bis(2-hydroxyethyl) terephthalate condensates with a molecular weight between small molecules and high polymers, such as bis(2-hydroxyethyl) terephthalate dimers, trimers, tetramers, etc.

[0025] Since germanium-based catalysts are insoluble in water and diols, when preparing the catalyst solution, in the present invention, an alkali metal compound and / or an alkaline earth metal compound are first pre-dispersed in ultrapure water to obtain a pre-dispersed solution, and then the germanium-based catalyst is added to the pre-dispersed solution and stirred until it is completely transparent and clear (the transparent and clear means that the light transmittance of the solution is above 90%), and finally diol is added to obtain the catalyst solution. This is because the germanium-based catalyst forms germanate with the alkali metal compound and the alkaline earth metal compound, which can be dissolved in diol, so as to obtain a catalyst solution with uniform dispersion.

[0026] Examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, sodium acetate, lithium hydroxide, lithium acetate, potassium acetate, cesium hydroxide, cesium acetate, etc. Examples of the alkaline earth metal compound include magnesium acetate, calcium acetate, barium acetate, etc. The alkali metal compound and the alkaline earth metal compound can be used alone or in combination.

[0027] The germanium-based catalyst refers to a substance having a catalytic effect in the polyester reaction process, such as germanium dioxide, germanium monoxide, germanium disulfide, germanium monosulfide, germanium monoselenide, germanium chloride, germanium fluoride, tetraethylgermanium, n-butylgermanium, isobutylgermanium, etc. Considering the stability and cost of product use, etc., the present invention preferably uses germanium dioxide as the germanium-based catalyst.

[0028] In order to improve the dispersion of the germanium-based catalyst in the catalyst solution and even in the polyester reaction system, in the preparation of the catalyst solution, the molar ratio of the germanium element in the germanium-based catalyst to the sum of the alkali metal element in the alkali metal compound and the alkaline earth metal element in the alkaline earth metal compound needs to be within the range of 0.02 to 4.00. Because if the molar ratio is lower than 0.02, that is, the sum of the alkali metal element and the alkaline earth metal element is too much relative to the germanium element, there will be too much free alkali metal element and alkaline earth metal element in the obtained polyester composition, which will cause the heat resistance of the polyester composition to deteriorate and the gel to become larger; if the molar ratio is higher than 4.00, that is, the sum of the alkali metal element and the alkaline earth metal element is too little relative to the germanium element, then the amount of the alkali metal compound and the alkaline earth metal compound is not enough to effectively dissolve the germanium-based catalyst, and it cannot effectively improve the dispersion of the germanium-based catalyst in the catalyst solution and the polyester reaction system. Under the same addition amount of the germanium-based catalyst, the polyester reaction time is prolonged, the foreign matters such as the aggregation of the germanium-based catalyst increase, and the terminal carboxyl group content of the polyester composition increases. Considering the dispersion effect of the germanium-based catalyst and the foreign matter content in the polyester composition, etc., the molar ratio of the germanium element in the germanium-based catalyst to the sum of the alkali metal element in the alkali metal compound and the alkaline earth metal element in the alkaline earth metal compound is preferably 0.04 to 1.60.

[0029] By the above method, a catalyst solution containing a germanium-based catalyst, an alkali metal compound and / or an alkaline earth metal compound can be prepared, and the molar ratio of germanium element to the sum of alkali metal elements and alkaline earth metal elements is in the range of 0.02 to 4.00. The catalyst solution can be used as a polymer, especially a polyester reaction catalyst.

[0030] The present invention also provides a polyester composition mainly prepared from an aromatic dicarboxylic acid or its esterification derivative and an aliphatic diol as main raw materials by reacting in the presence of the catalyst solution. As mentioned above, since the germanium-based catalyst exists in the polyester reaction system in a free state, it is easily extracted together with the diol during the extraction of the diol in the polyester reaction system, and the extraction ratio is about 50% of the total amount. Therefore, the molar ratio of the remaining germanium element to the sum of alkali metal elements and alkaline earth metal elements in the polyester composition is below 4.00, preferably below 0.80.

[0031] After using the catalyst solution of the present invention, the germanium-based catalyst has good dispersibility in the polyester reaction system and its catalytic activity is also improved. Therefore, the polyester reaction rate is fast and the content of linear oligomers in the obtained polyester composition is relatively small. The content of the linear oligomers relative to the polyester composition is below 100 ppm.

[0032] The amount of the catalyst solution added during the reaction of the polyester composition is considered from aspects such as whether it meets the catalytic activity of the polyester reaction, whether foreign substances are generated, and cost control. If the addition amount of the catalyst solution is too large, it will affect the dispersion of the germanium-based catalyst in the polyester reaction system, generate foreign substances, and the cost will also increase; if the addition amount of the catalyst solution is too small, the polyester reaction will be too slow, the reaction will be difficult to proceed, and the content of linear oligomers in the obtained polyester composition will be relatively large. Therefore, the addition amount of the catalyst solution during the reaction of the polyester composition of the present invention is preferably 2.0 to 400.0 ppm, more preferably 4.0 to 300.0 ppm in terms of the germanium element therein. After removing the part extracted together with the diol, the germanium element content in the polyester composition is preferably 1.0 to 200.0 ppm, more preferably 2.0 to 150.0 ppm relative to the total amount of the polyester composition.

[0033] The total amount of alkali metal elements and alkaline earth metal elements in the polyester composition is related to the molar ratio of the germanium-based catalyst to the sum of the alkali metal compound and the alkaline earth metal compound in the catalyst solution, as well as the addition amount of the catalyst solution during the polyester reaction. However, under the condition of satisfying the addition amount of the catalyst solution, it is also necessary to select a catalyst solution with a certain molar ratio of the germanium-based catalyst to the sum of the alkali metal compound and the alkaline earth metal compound, so that the total amount of alkali metal elements and alkaline earth metal elements in the final polyester composition will not be too much. Otherwise, the heat resistance and color tone of the obtained polyester composition will deteriorate. In order to obtain a polyester composition with good heat resistance and color tone, the present invention preferably has the total content of alkali metal elements and alkaline earth metal elements in the polyester composition below 300 ppm, more preferably below 150 ppm.

[0034] According to the types of the alkali metal compound and the alkaline earth metal compound in the catalyst solution, the alkali metal elements in the polyester composition are selected from one or more of lithium, sodium, potassium, and cesium, and the alkaline earth metal elements are selected from one or more of magnesium, calcium, and barium.

[0035] In order to inhibit side reactions during the polyester reaction, the present invention preferably adds a phosphorus compound in the polyester reaction. The phosphorus compound can coordinate with the germanium-based catalyst to reduce the generation of side reactions. The higher the addition amount of the phosphorus compound, the slower the rate of side reactions during the polyester reaction. However, if the addition amount of the phosphorus compound is too high, the rate of the polyester reaction will also become slower, the polymerization time will be prolonged, or a polymer with the target viscosity cannot be obtained; if the addition amount of the phosphorus compound is too low, side reactions cannot be effectively inhibited, and the heat resistance of the polyester composition cannot be significantly improved, and the gel cannot be reduced. The addition amount of the phosphorus compound in the present invention, calculated as phosphorus element, is equivalent to 1.0 - 230.0 ppm of the polyester composition, more preferably 8.0 - 225.0 ppm. Within the preferred range, the catalytic activity of the germanium-based catalyst can be better maintained, side reactions can be reduced, and the heat resistance and color tone of the polyester composition can be maintained. According to the preferred addition range, the phosphorus element content in the polyester composition is preferably 1.0 - 230.0 ppm, more preferably 8.0 - 225.0 ppm.

[0036] The stabilizer phosphorus compound in the present invention can be commonly used stabilizers such as phosphoric acid, trimethyl phosphate, and triphenyl phosphate.

[0037] The preparation method of the polyester composition in the present invention is specifically as follows: an aromatic dicarboxylic acid or its esterification derivative and an aliphatic diol are subjected to esterification or transesterification to obtain an oligomer, and then the oligomer is subjected to polycondensation reaction to obtain a polyester composition, and a catalyst solution mainly containing a germanium-based catalyst and an alkali metal compound and / or an alkaline earth metal compound is added during the polyester reaction.

[0038] If the addition amount of the catalyst solution is too large, it will affect the dispersion of the germanium-based catalyst in the polyester reaction system, resulting in foreign matters and increased costs. If the addition amount of the catalyst solution is too small, the polyester reaction will be too slow, the reaction will be difficult to proceed, and the content of linear oligomers in the obtained polyester composition will be relatively high. Therefore, in the reaction process of the polyester composition of the present invention, the addition amount of the catalyst solution, calculated as germanium element therein, is preferably equivalent to 2.0 - 400.0 ppm of the polyester composition, more preferably 4.0 - 300.0 ppm. Within this range, the heat resistance of the polyester composition can be ensured to be relatively good, the foreign matters are relatively few, and the hue is relatively good.

[0039] The higher the addition amount of the phosphorus compound, the slower the rate of side reactions during the polyester reaction. However, if the addition amount of the phosphorus compound is too high, the rate of the polyester reaction will also slow down, the polymerization time will be prolonged, or a polymer with the target viscosity cannot be obtained. If the addition amount of the phosphorus compound is too low, the side reactions cannot be effectively inhibited, and the heat resistance of the polyester composition cannot be significantly improved, and the gel formation cannot be reduced. The present invention preferably uses the addition amount of the phosphorus compound, calculated as phosphorus element, equivalent to 1.0 - 300.0 ppm of the total amount of the polyester composition, more preferably 8.0 - 225.0 ppm. The polyester composition obtained within this range has few linear oligomers, good heat resistance, few gels, and a relatively good hue.

[0040] The catalyst solution and the phosphorus compound can be added at any stage of the polyester reaction. Specifically, they can be added at the esterification or transesterification reaction stage, at the end of the esterification or transesterification reaction stage, before the polycondensation reaction, or at any stage from the start to the end of the polycondensation reaction. It is preferably added before the polycondensation reaction.

[0041] When selecting a specific polyester preparation process, the present invention has no particular limitation. It can be an intermittent polymerization method or a continuous polymerization method. According to the existing conventional polyester preparation methods, appropriate reaction temperatures and pressures can be selected in the esterification reaction stage and the polycondensation reaction stage. According to the required functions, co-catalysts such as manganese acetate, magnesium acetate, calcium acetate and other compounds, delustering agents such as titanium dioxide, colorants such as blue dyes, flame retardants such as phosphorus-based flame retardants, and antioxidants such as IR1010 can also be added to the polyester.

[0042] The polyester composition of the present invention has good hue and heat resistance, few gel formations and foreign matters. The heat resistance index %BB after heat treatment at 290 °C for 6 hours under nitrogen conditions is 0.55 or less; the gel rate after heat treatment at 300 °C for 6 hours in a mixed gas of nitrogen and oxygen with an oxygen concentration of 1 vol% is 10.0 wt% or less; the haze value is 5.00% or less; the content of cyclic trimers is 1.0 wt% or more. It can be used for the preparation of fibers, films, engineering plastics, etc.

[0043] The measurement methods and evaluation methods for the various indexes of the present invention are as follows:

[0044] (1) Intrinsic viscosity (IV)

[0045] Dissolve 0.8 g of the polyester composition chips in 10 ml of o-chlorophenol solution. Under the condition that the water bath temperature is 25 ± 0.2 °C, use an Ubbelohde viscometer to measure its intrinsic viscosity (take the average value after three tests).

[0046] (2) Carboxyl content (COOH)

[0047] Determined by optical titration. Dissolve the polyester chips in a mixed solution of o-cresol and chloroform (weight ratio 70:30), add bromothymol blue indicator, and then titrate with an ethanol solution of 0.05 mol / L potassium hydroxide (take the average value after two tests).

[0048] (3) DEG content

[0049] Take 0.5 g of the sample, add 1.25 ml of solvent (internal standard 1,6-hexanediol / solvent B = 5 mg / 1.25 ml), heat to dissolve, add 10 ml of methanol, cool in an ultrasonic bath until ammonium salt precipitates; then add 8 g of terephthalic acid for neutralization, filter with filter paper to obtain a clear solution. Take 2 μl of the filtrate and inject it into a GC for analysis and determination (take the average value after two tests).

[0050] (4) Heat resistance (%BB)

[0051] Put 8 g of polyester composition chips into two small test tubes respectively, heat-treat them under a nitrogen atmosphere at 290 °C for 6 hours respectively. Compare the limiting viscosity "η0" after 0 minutes of treatment and the limiting viscosity "ηt" after 6 hours of treatment. After conversion according to the change in number-average molecular weight, calculate the ratio of ester bonds broken due to thermal decomposition (take the average value after two tests).

[0052] %BB = 0.27 × (1 / 「ηt」 4 / 3 — 1 / [η0」 4 / 3 ).

[0053] (5) Determination of the contents of germanium element, alkali metal elements and alkaline earth metal elements in the polyester composition

[0054] Take a certain amount of the polyester composition, use fluorescent X-ray for spectral analysis, qualitatively identify elements such as titanium and phosphorus, and quantitatively determine the element contents according to the intensity of the spectrum (take the average value after two tests).

[0055] (6) Determination of the contents of various linear oligomers in the polyester composition

[0056] Using the internal standard method of liquid chromatography, accurately weigh 0.1000 g of the polyester composition, add o-chlorophenol, dissolve the polyester composition completely at 150 °C, then cool it, add the internal standard solution of p-terphenyl / dichloromethane, and then add the methanol solution to precipitate the polyester. After centrifugal separation, take the solution for the determination of various linear oligomers.

[0057] (7) Hue b value

[0058] Determine according to GB / T 14190-1993 (take the average value after three tests).

[0059] (8) Haze value of the polyester composition

[0060] Dissolve 2 g of the polymer in 20 ml of a mixed solvent of phenol / tetrachloroethane (volume ratio 3 / 2), and test it with a HZ-V3 type HAZE tester manufactured by Suga Test Instruments Co., Ltd. (take the average value after two tests).

[0061] (9) Gel fraction

[0062] Crush the polyester composition into powder with a particle size of 300 μm or less, take 0.5000 - 0.5999 g of this powder as a sample, and dry it under vacuum conditions at 50 °C for more than 2 hours. After drying, pass a nitrogen-oxygen mixed gas with an oxygen concentration of 1 vol% through the sample and conduct heat treatment at a temperature of 300 °C. After 6 hours, take it out and cool it to room temperature. The heat-treated sample is dissolved in 20 ml of hexafluoroisopropanol (HFIP) at room temperature for 1 hour, then filtered through a 400 - 800 mesh metal filter, washed with dichloromethane, and finally the HFIP-insoluble matter is dried and weighed. The calculation formula for the gel fraction is as follows (take the average value after two tests):

[0063] Gel fraction (wt%) = (weight of HFIP-insoluble matter / weight of sample) × 100%.

[0064] Example 01:

[0065] (1) Preparation of the catalyst solution

[0066] First, weigh 110.2 g of sodium hydroxide and add it to pure water for pre-dispersion to prepare a uniformly dispersed and transparent pre-dispersion solution. Then add 28.8 g of germanium dioxide to the pre-dispersion solution, stir until it is completely transparent and clear, and then add ethylene glycol to prepare the catalyst solution, where the molar ratio of germanium element to sodium element is 0.10.

[0067] (2) Preparation of the polyester composition

[0068] At a temperature of 250°C, 166 parts by weight of terephthalic acid (TPA) and 71.3 parts by weight of ethylene glycol (EG) were added to an esterification reactor, and the esterification reaction was carried out under atmospheric pressure. When the esterification reaction was completed, the temperature in the esterification reactor was 250°C, and water was fractionated out to obtain a low-molecular polymer.

[0069] The obtained low-molecular polymer was added with a catalyst mixture equivalent to 20.0 ppm of the total amount of the polyester composition in terms of germanium element at 250°C, and then stirred for 5 minutes. After that, phosphoric acid equivalent to 30.0 ppm of the total amount of the polyester composition in terms of phosphorus element was added, and the polycondensation reaction was started under reduced pressure and increased temperature. The temperature was raised from 250°C to 290°C, and the pressure was reduced to 25 Pa. The final temperature and final pressure were reached in 90 minutes, and after a period of reaction, the polymer reached the target IV and was discharged. When discharged, the polymer was in a uniform strip shape, cooled in a water bath, and pelletized to obtain polyester composition chips. The specific formulation and physical properties are shown in Table 1.

[0070] Examples 02 - 22:

[0071] The preparation process was the same as that of Example 1, and the specific formulation and physical properties are shown in Tables 1 and 2.

[0072] Comparative Example 01:

[0073] At a temperature of 250°C, 166 parts by weight of TPA and 71.3 parts by weight of EG were added to an esterification reactor, and the esterification reaction was carried out under atmospheric pressure. When the esterification reaction was completed, the temperature in the esterification reactor was 250°C, and water was fractionated out to obtain a low-molecular polymer.

[0074] The obtained low-molecular polymer was added with germanium dioxide equivalent to 50.00 ppm of the total amount of the polyester composition in terms of germanium element (previously prepared as a slurry with ethylene glycol) at 250°C, and then stirred for 5 minutes. After that, phosphorus compound A equivalent to 100.0 ppm of the total amount of the polyester composition in terms of phosphorus element was added, and the polycondensation reaction was started under reduced pressure and increased temperature. The temperature was raised from 250°C to 290°C, and the pressure was reduced to 25 Pa. The final temperature and final pressure were reached in 90 minutes, and after a period of reaction, the polymer reached the target IV and was discharged. When discharged, the polymer was in a uniform strip shape, cooled in a water bath, and pelletized to obtain polyester composition chips. The specific formulation and physical properties are shown in Table 3.

[0075] Since the germanium-based catalyst was not prepared as a solution but directly added when adding the germanium-based catalyst, the catalytic activity of germanium dioxide was not high, and germanium dioxide was not evenly dispersed in the polyester composition, resulting in many foreign substances and high haze in the polyester composition.

[0076] Comparative Example 02:

[0077] (1) Preparation of the catalyst solution

[0078] First, weigh 624 g of sodium hydroxide and add it to pure water for pre-dispersion to prepare a uniformly dispersed and transparent pre-dispersion solution. Then, add 28.8 g of germanium dioxide to the pre-dispersion solution, stir until it is completely transparent and clear, and then add ethylene glycol to obtain a catalyst solution, where the molar ratio of germanium element to sodium element is 0.017.

[0079] (2) Preparation of polyester composition

[0080] At a temperature of 250 °C, add 166 parts by weight of TPA and 71.3 parts by weight of EG to the esterification reactor, and carry out the esterification reaction under atmospheric pressure. When the esterification reaction is completed, the temperature in the esterification reactor is 250 °C, and small molecule polymers are obtained by distilling off water.

[0081] Add germanium dioxide equivalent to 8.00 ppm of the total amount of the polyester composition in terms of germanium element to the obtained small molecule polymers at 250 °C, stir for another 5 minutes, and then add phosphoric acid equivalent to 30.0 ppm of the total amount of the polyester composition in terms of phosphorus element. Start the polycondensation reaction under reduced pressure and increasing temperature. The temperature rises from 250 °C to 290 °C and the pressure drops to 25 Pa. The final temperature and final pressure are reached in 90 minutes, and after a period of reaction, the polymer reaches the target IV and is discharged. When discharging, the polymer is in a uniform strip shape, cooled in a water bath, and pelletized to obtain polyester composition chips. The specific formulation and physical properties are shown in Table 3.

[0082] The amount of alkali metal compound in the catalyst solution is relatively large, the molar ratio of germanium element to alkali metal element is less than 0.02, and the color difference and heat resistance of the obtained polyester composition are poor.

[0083] Comparative Example 03:

[0084] (1) Preparation of catalyst solution

[0085] First, weigh 15.6 g of sodium hydroxide and add it to pure water for pre-dispersion to prepare a uniformly dispersed and transparent pre-dispersion solution. Then, add 173.3 g of germanium dioxide to the pre-dispersion solution, stir until it is completely transparent and clear, and then add ethylene glycol to obtain a catalyst solution, where the molar ratio of germanium element to sodium element is 4.22.

[0086] (2) Preparation of polyester composition

[0087] At a temperature of 250 °C, add 166 parts by weight of TPA and 71.3 parts by weight of EG to the esterification reactor, and carry out the esterification reaction under atmospheric pressure. When the esterification reaction is completed, the temperature in the esterification reactor is 250 °C, and small molecule polymers are obtained by distilling off water.

[0088] The obtained small molecule polymer was added with a mixed solution equivalent to 1.00 ppm of the total amount of the polyester composition in terms of germanium element at 250 °C, and then stirred for 5 minutes. Then phosphoric acid equivalent to 20.0 ppm of the total amount of the polyester composition in terms of phosphorus element was added, and the polycondensation reaction was started under reduced pressure and increasing temperature. The temperature was raised from 250 °C to 290 °C and the pressure was reduced to 25 Pa. The final temperature and final pressure were reached in 90 minutes, and after a period of reaction, the polymer reached the target IV and was discharged. When discharging, the polymer was in a uniform strip shape, cooled in a water tank and pelletized to obtain polyester composition slices. The specific formulation and physical properties are shown in Table 3.

[0089] Since the amount of sodium hydroxide was too small, the dispersion of the germanium-based catalyst in both the catalyst solution and the polyester reaction system was poor, resulting in a relatively high haze value and a relatively high foreign matter content of the obtained polyester composition.

[0090]

[0091]

[0092] Table 3

[0093]

Claims

1. Catalyst solution, Its characteristics are: The catalyst solution contains a germanium catalyst and an alkali metal compound and / or an alkaline earth metal compound, and the molar ratio of germanium to the sum of the alkali metal element and the alkaline earth metal element is 0.02-4.

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2. A method for preparing the catalyst solution according to claim 1, Its characteristics are: First, the alkali metal compound and / or alkaline earth metal compound is pre-dispersed in ultrapure water to obtain a pre-dispersion liquid, and then a germanium catalyst is added to the pre-dispersion liquid, stirred until completely transparent and clear, and finally a diol is added to obtain a catalyst solution; when adding, the molar ratio of the germanium element in the germanium catalyst to the sum of the alkali metal element in the alkali metal compound and the alkaline earth metal element in the alkaline earth metal compound is 0.02-4.

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3. A polyester composition, mainly obtained by reacting an aromatic dicarboxylic acid or an esterified derivative thereof with an aliphatic diol in the presence of the catalyst solution of claim 1, Its characteristics are: The polyester composition contains germanium and alkali metal elements and / or alkaline earth metal elements, and the molar ratio of the germanium element to the sum of the alkali metal elements and the alkaline earth metal elements is less than 4.

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4. The polyester composition according to claim 3, Its characteristics are: The linear oligomer content in the polyester composition is below 100 ppm.

5. The polyester composition according to claim 3, Its characteristics are: The alkali metal element is selected from one or more of lithium, sodium, potassium and cesium, and the alkaline earth metal element is selected from one or more of magnesium, calcium and barium.

6. The polyester composition according to claim 3, Its characteristics are: The content of germanium in the polyester composition is equivalent to 1.0 to 200.0 ppm of the total amount of the polyester composition.

7. The polyester composition according to claim 3, Its characteristics are: The polyester composition contains phosphorus in an amount equivalent to 1.0 to 230.0 ppm of the total amount of the polyester composition.

8. The polyester composition according to claim 3, Its characteristics are: The total amount of alkali metal elements and alkaline earth metal elements in the polyester composition is less than 300 ppm corresponding to the polyester composition.

9. The polyester composition according to claim 3, Its characteristics are: The heat resistance index %BB of the polyester composition after heat treatment at 290°C×6hr under nitrogen conditions is below 0.55, the gel fraction of the polyester composition after heat treatment at 300°C×6hr in a mixed gas of nitrogen and oxygen with an oxygen concentration of 1 vol% is below 10.0 wt%, and the haze value of the polyester composition is below 5.00%.

10. The method for preparing the polyester composition according to claim 3, comprising: esterifying or transesterifying aromatic dicarboxylic acid or its esterified derivative with aliphatic diol to obtain oligomers, and then subjecting the oligomers to polycondensation to obtain the polyester composition. Its characteristics are: The catalyst solution according to claim 1 is added during the polyester reaction process.

11. The method for preparing the polyester composition according to claim 10, Its characteristics are: The amount of the catalyst solution added is equivalent to 2.0 to 400.0 ppm of the polyester composition in terms of germanium element.

12. The method for preparing the polyester composition according to claim 10, Its characteristics are: During the polyester reaction, a phosphorus compound is added in an amount equivalent to 1.0 to 300.0 ppm of the total amount of the polyester composition in terms of phosphorus element.

13. Use of the polyester composition according to claim 3 in films.

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