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CN-121991333-A - Preparation method of low-color-value polyethylene furandicarboxylate

CN121991333ACN 121991333 ACN121991333 ACN 121991333ACN-121991333-A

Abstract

The invention provides a preparation method of low-color-value polyethylene furandicarboxylate. The germanium-titanium composite catalyst is used as the catalyst for preparing the polyethylene furan dicarboxylate, so that the problems of slow reaction and deep color of the polyethylene 2, 5-furan dicarboxylate are solved. According to the preparation method of the polyethylene glycol furandicarboxylate, all raw materials are added only before the reaction, no auxiliary agent or other catalyst is required to be added in the middle process, the process is very simple, the process is environment-friendly, and industrialization is facilitated.

Inventors

  • CAI WEILONG
  • YANG SHILONG
  • ZHENG ZHENG
  • LIU LONGMIN
  • ZHANG YU
  • LIN YI
  • WU MEIHUA
  • CHEN HUAIYIN

Assignees

  • 福州大学
  • 清源创新实验室

Dates

Publication Date
20260508
Application Date
20260331

Claims (10)

  1. 1. The preparation method of the low-color-value polyethylene furandicarboxylate is characterized by comprising the following steps of: (1) The esterification reaction stage comprises the steps of adding quantitative glycol into a pulping kettle by adopting a one-step esterification method, starting stirring, then adding a furandicarboxylic acid, a germanium-titanium composite catalyst and a stabilizer, and carrying out esterification reaction under the protection of inert gas, wherein the mol ratio of the furandicarboxylic acid to the glycol is 1:1.1-2.0, the pressure is maintained at 0.3-0.5MPa in the esterification reaction process, the temperature is 180-200 ℃ and the time is 2.0-3.0 hours; (2) The polycondensation reaction stage comprises a pre-polycondensation stage and a high vacuum stage, wherein in the pre-polycondensation stage, the pressure is smoothly pumped from normal pressure to below 1kPa of absolute pressure, the temperature is controlled to be 230-250 ℃ for 0.5 hour, the high vacuum stage is carried out after the pre-polycondensation is finished, the vacuum is continuously pumped to below 50Pa of absolute pressure, the reaction temperature is controlled to be 230-250 ℃, and the reaction time is controlled to be 2.5-3.5 hours; (3) And (3) discharging, namely charging nitrogen to positive pressure after the reaction is finished, then opening a discharging valve, extruding the melt from a casting belt head, performing underwater granulating, and drying to obtain the low-color-value polyethylene furandicarboxylic acid glycol ester.
  2. 2. The method of claim 1, wherein the stabilizer is trimethyl phosphate.
  3. 3. The method according to claim 1, wherein the stabilizer is added in an amount of 0.012-0.035wt% of furandicarboxylic acid.
  4. 4. The method according to claim 1, wherein the germanium-titanium complex catalyst is added in an amount of 0.03 to 0.06wt% of furandicarboxylic acid.
  5. 5. The method according to claim 1, wherein the method for preparing the germanium-titanium composite catalyst comprises the steps of: 1) Under the protection of N 2 atmosphere, dissolving P123 serving as a template agent in absolute ethyl alcohol, stirring to a transparent state, adding tetraethoxysilane TEOS and deionized water, magnetically stirring, heating and refluxing, keeping the heating temperature at 60 ℃, and pre-hydrolyzing for 2 hours to prepare silica sol; 2) Simultaneously preparing germanium-titanium mixed liquid, dissolving tetrabutyl titanate TBOT and germanium tetrachloride in absolute ethyl alcohol, dropwise adding 1-2 drops of absolute acetic acid, adding citric acid CA, stirring for 30min, slowly adding the germanium-titanium mixed liquid into silica sol, and continuously stirring until wet gel is formed; 3) Placing the wet gel which is just formed into a sealed container, soaking the wet gel into absolute ethyl alcohol for ageing for 24 hours, replacing the wet gel with absolute ethyl alcohol for 3 times, placing the wet gel into an autoclave for supercritical drying, drying the wet gel for 12 hours under the conditions of 80 ℃ and 15MPa, grinding the obtained solid, placing the ground solid into a roasting furnace for roasting, wherein the roasting process is that the temperature is increased to 300 ℃ at 1 ℃ per minute, preserving the heat for 2 hours, roasting the wet gel for 4 hours at 2 ℃ to 500 ℃, and naturally cooling the wet gel to room temperature to obtain the germanium-titanium composite catalyst.
  6. 6. The method according to claim 5, wherein the addition amount of P123 in the preparation process of the germanium-titanium composite catalyst is 2.5% -3.5% of the total mass of the silica sol.
  7. 7. The method according to claim 5, wherein the molar ratio n (TEOS): n (C 2 H 5 OH)：n(H 2 O) =1:8:4 during the preparation of the germanium-titanium composite catalyst.
  8. 8. The method according to claim 5, wherein the molar ratio n (TBOT): n (CA) =1:0.6-1.0 during the preparation of the germanium-titanium composite catalyst.
  9. 9. The method according to claim 5, wherein the molar ratio n (ti+ge): n (Si) =4:1 during the preparation of the germanium-titanium composite catalyst.
  10. 10. The method according to claim 5, wherein the molar ratio n (Ge): n (Ti) =1-2.5:1 during the preparation of the germanium-titanium composite catalyst.

Description

Preparation method of low-color-value polyethylene furandicarboxylate Technical Field The invention relates to the technical field of high polymer material synthesis, in particular to a preparation method of low-color-value polyethylene furandicarboxylate. Background Polyethylene terephthalate (PET) is the most widely used polyester material at present, but the raw materials are mainly derived from non-renewable petroleum resources and are difficult to degrade in natural environment, so that serious 'white pollution' problem is caused, and searching for bio-based plastics to replace traditional petroleum-based polyesters is the most effective solution at present, ethylene glycol is already of bio-based origin, so that bio-based 2, 5-furandicarboxylic acid (FDCA) is considered as one of ideal substitutes for polyethylene furandicarboxylic acid (PEF) synthesized by taking PTA (terephthalic acid) as a monomer, and the lower melting temperature of PEF is more beneficial to processing, has higher tensile modulus and glass transition temperature, and is most important to have excellent gas barrier property. However, there are some inherent drawbacks to PEF synthesis: 1. Because of the influence of side reactions such as decarboxylation, the melt-prepared PEF polyester is dark yellow or black, and the chromaticity is not attractive, so that the market applicability of the PEF is poor. 2. The polycondensation reaction rate is slow, the reaction time is long, the polycondensation reaction time is generally 4-8h, and the intrinsic viscosity of the obtained polyester chip is low, which is only about 0.5 dL/g. The most effective solution to these drawbacks is to modify catalysts, conventional catalysts such as antimony, titanium and germanium based. Although the antimony catalyst has high catalytic efficiency, heavy metals have potential toxicity, and the polymer is likely to have yellow color and luster, so that the appearance of the product is affected. The titanium catalyst has no toxicity, high activity and short reaction time, but has high catalytic activity on side reaction, and the polymer turns yellow to influence the appearance. The germanium catalyst has low toxicity, good color of the obtained product, low catalytic activity, large addition amount, long reaction time and high price, and causes high production cost. Gruter, et al, synthesized PEF with various catalysts, and screened the catalysts, and considered that tin-based catalysts and antimony-based catalysts were good catalysts for synthesizing PEF, and the viscosity of the synthesized PEF was only about 0.4 dL/g. WUJ et al, using an organic nonmetallic catalyst to catalyze PEF synthesis, the synthesized PEF has a medium molecular weight and a viscosity of 0.54 dL/g. CN 111269405A discloses a preparation method of color-changing-inhibiting bio-based polyester, in the esterification stage of the method, esterification reaction and transesterification reaction are required to be carried out, and the esterification products of the esterification reaction and the transesterification reaction are mixed and then polymerized, so that the reaction flow is more complex, the production cost is high, the b value of the prepared bio-based polyester is more than 15, and the color is still darker. CN 106243331B discloses a method for preparing polyethylene furandicarboxylate by using nitrogen-containing catalyst, the intrinsic viscosity of the prepared polyester is 0.6 dL/g, the absorbance is 0.1, but the esterification time is 4 hours, the polycondensation time is 5 hours, the reaction time is too long and the process is complicated. The selection and use of the catalyst are important reasons for darkening the color of the PEF, and there is no catalyst in the prior art which can efficiently prepare PEF with moderate molecular weight and good color. Disclosure of Invention In order to overcome the defects of the prior art, the invention provides a preparation method of polyethylene 2, 5-furandicarboxylic acid glycol ester, which solves the problems of slow reaction and dark color of the polyethylene 2, 5-furandicarboxylic acid glycol ester. In order to achieve the above purpose, the invention adopts the following technical scheme: the preparation method of the PEF polyester pellets comprises the following steps: a. The esterification reaction stage comprises the steps of adding quantitative glycol into a pulping kettle by adopting a one-step esterification method, starting stirring, then adding a furandicarboxylic acid, a germanium-titanium composite catalyst and a stabilizer, and carrying out esterification reaction under the protection of inert gas, wherein the molar ratio of the furandicarboxylic acid to the glycol is 1:1.1-2.0, the pressure is maintained at 0.3-0.5MPa in the esterification reaction process, the temperature is 180-200 ℃ and the time is 2.0-3.0 hours, the reaction end point is judged to reach 96% of theoretical water yield by the distilled amount