Polyester polycondensation catalyst and preparation method and application thereof

[0024] Example 1. Preparation of polyester polycondensation catalyst

[0025] Take 5 mL of concentrated hydrochloric acid, 10 mL of ethanol, mix with 19.6 g of ethyl orthosilicate (TEOS) at room temperature, and stir for 1 hour to obtain the product A SiO 2 Sol.

[0026] Mix 2.5 g of tetrabutyl titanate and 10 mL of concentrated hydrochloric acid at room temperature, and stir at room temperature for 1 hour to obtain the product BTiO 2 Sol.

[0027] The product A SiO 2 Sol and product B TiO 2 The sol was mixed and stirred at 50°C for 12 hours to obtain the product CTiO 2 /SiO 2 Sol.

[0028] At 80℃, the product C TiO 2 /SiO 2 The sol was dried under vacuum to obtain catalyst D.

[0029] The product C TiO 2 /SiO 2 The sol was freeze-dried to obtain catalyst E.

[0030] The product C TiO 2 /SiO 2 The sol is placed in a semi-permeable membrane and placed in deionized water to remove Cl - , Get catalyst F.

[0031] The product C TiO 2 /SiO 2 React with 0.3 g of caprolactam to obtain catalyst G.

[0032] The product C TiO 2 /SiO 2 React with 0.05g of silane coupling agent KH550 to obtain catalyst H.

[0033] The product C TiO 2 /SiO 2 React with 0.25g 1-hexadecyl-3-methylimidazole bromide to obtain catalyst I.

[0034] Example 2: Preparation of polyester polycondensation catalyst

[0035] Take 5 mL of concentrated hydrochloric acid, 10 mL of ethanol, mix with 19.6 g of ethyl orthosilicate (TEOS) at room temperature, and stir for 1 hour to obtain the product A SiO 2 Sol.

[0036] Take 2.5g TiCl 4 Add 20ml EG dropwise at 0℃, and pass in dry NH 3 The gas is prepared according to the Nelles method provided in the following literature, but the product is not hydrolyzed, and then it is supported on SiO 2 Above the sol: Li Dacheng, Zhou Dali, Chen Chaozhen, etc. Synthesis of Titanium Ethoxide and Preparation of TiO by Hydrolysis 2 Research on Micropowder[J]. Functional Materials, 1995, 26(3):278-282.

[0037] In the above preparation steps, quickly add the resulting product to A to obtain TiO 2 /SiO 2 Sol J.

[0038] J was freeze-dried under vacuum to obtain catalyst K.

[0039] Treat J with a low-temperature hydrothermal method, with a hydrothermal temperature of 50-200°C and a hydrothermal time of 1-144 hours, to obtain a polyester polycondensation catalyst numbered L.

[0040] 1.69 g of triphenyl phosphate was added to sol J and freeze-dried to obtain catalyst M.

[0041] Taking catalyst D and catalyst K as examples, the electron binding energy of Ti was measured by X-ray photoelectron spectroscopy. X-ray photoelectron energy spectrum such as figure 1 with figure 2 As shown, it was found that when no organic matter was added (catalyst D), Ti 2p The electron binding energy of is 459.8eV. After adding KH550 (catalyst H), Ti 2p The electron binding energy is reduced to 457.8eV. TiO mentioned earlier 2 The particles are supported on SiO 2 On the surface of the particles, it means that nitrogen or phosphorus-containing organic matter is covered with TiO 2 /SiO 2 The surface of the sol particles and Ti form a coordination effect.

[0042] The particle size of the catalyst prepared in Example 1 was measured, and the results are shown in Table 1. The data shows that the introduction of organic components combined with appropriate drying and purification methods can control the particle size of the catalyst and help improve its activity.

[0043] Table 1. Particle size of the catalyst prepared in Example 1

[0044]

[0045] Electron probe microscope (EPMA) was used to determine the composition of catalyst D and catalyst I. The results showed that the molar ratio of Si to Ti in catalyst D was 12, which was in good agreement with the theoretical value (12.8); while in catalyst I, Si The molar ratio to Ti is 12.3, and the organic content is 3.5 wt%, which is also very close to the theoretical value, indicating that the synthesis method adopted by the present invention can well control the ratio of each component of the catalyst.

[0046] Example 3. Application of polyester polycondensation catalyst as a catalyst in the preparation of polyester materials

[0047] The steps for preparing PET polyester material using the polyester polycondensation catalyst provided in Example 1 of the present invention are as follows:

[0048] Take 86.4 g of terephthalic acid and 32.3 g of ethylene glycol, and carry out esterification under the conditions of a pressure of 0.3 MPa and a temperature of 220-250° C. until the theoretical value of water is evaporated. 1 mg of one of the catalysts prepared in Example 1 (catalyst D-I) was added to obtain PET material N-S, respectively. The polycondensation time and product properties are shown in Table 2.

[0049] It can be seen from the data in Table 2 that the electron binding energy of titanium and the particle size of the catalyst greatly affect the activity of the catalyst: for catalysts D, E, and F, the particle size decreases in order, the activity increases, and the product performance is also improved; After the introduction of nitrogen-containing compounds and Ti for coordination, the activity is further improved, and the product performance (specific performance) far exceeds that of the product prepared by the antimony catalyst. The sample obtained with a larger particle size catalyst not only has a lower molecular weight, but also has a higher content of by-products such as terminal carboxyl groups and diethylene glycol, which may be caused by the excessively long polymerization time. The PET material prepared with a catalyst with a smaller particle size has a high molecular weight and relatively few product impurities. After the organic matter is introduced, the organic matter can not only coordinate with Ti, inhibit side reactions, but also further control the catalyst particle size. The obtained product not only has low impurity content (the content of terminal carboxyl groups and diethylene glycol is much lower than the product prepared by antimony catalyst), and the product has a good PET chain regularity so that the melting point of the product is as high as 260°C. Nano-sized TiO 2 /SiO 2 The particles also greatly promote the crystallization of PET, which is beneficial to the preparation of PET engineering plastics.

[0050] Table 2. Basic properties of PET products prepared with different catalysts

[0051]