阅读说明：本技术 一种基于高香草酸的生物质聚酯p、制备及其应用 (High vanillic acid-based biomass polyester P, and preparation and application thereof ) 是由 程正载 贾如艳 孙欣 王欢 蔡拴普 王林枫 杨迎澳 马里奥·高迪尔 于 2021-07-16 设计创作，主要内容包括：本发明公开了一种基于高香草酸的生物质聚酯、制备方法及用途,所述方法包括：采用碳酸亚乙酯把4-(5-(羟甲基)-5-甲基-1,3-二恶烷-2-基)-2-甲氧基苯酚进行羟乙基化,得到生物质二元醇单体M1；将高香草酸与二(2-溴乙基)醚偶联得到生物质二元酸单体M2。将所述生物质二元醇M1与生物质二元酸M2通过酯化和缩聚反应,得到聚合物粗品,精制后得到一种基于高香草酸的生物质聚酯,可用于制备显示器保护膜的主要原料。本发明反应过程绿色环保,产品具有优异的热学性能,力学性能和降解性能好等特点。(The invention discloses a homovanillic acid-based biomass polyester, a preparation method and application thereof, wherein the method comprises the following steps: hydroxyethylating 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane-2-yl) -2-methoxyphenol with ethylene carbonate to obtain a biomass diol monomer M1; homovanillic acid and di (2-bromoethyl) ether are coupled to obtain a biomass diacid monomer M2. The biomass diol M1 and the biomass diacid M2 are subjected to esterification and polycondensation reaction to obtain a polymer crude product, and the polymer crude product is refined to obtain the high vanillic acid-based biomass polyester which can be used as a main raw material for preparing a display protective film. The reaction process is green and environment-friendly, and the product has the characteristics of excellent thermal property, good mechanical property, good degradation property and the like.)

1. A biomass polyester P based on homovanillic acid is characterized by having a structure as shown in formula I:

formula I

In the structural formula, x is 20-130.

2. The preparation of a homovanillic acid based biomass polyester P according to claim 1, characterized in that the preparation comprises the following steps:

(1) synthesis of monomers

Synthesis of a diol monomer M1: at room temperature, N₂Under protection, 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol with CAS number 1089332-89-7 isAdding ethylene carbonate into a reaction container according to a certain proportion, adding N, N-dimethylformamide, stirring to dissolve the N, N-dimethylformamide, adding potassium carbonate which is 0.10-0.20 times of the amount of the ethylene carbonate, heating the reaction mixture to 150-170 ℃, continuously stirring for reaction for 2-4 hours, cooling to room temperature, and adding 0.10mol/L sodium hydroxide solution into the reaction mixture while stirring until the mixture is precipitatedAnd (3) precipitating, filtering, washing filter residues with distilled water for 2-3 times, and drying in a 50 ℃ oven for 1-2 hours to obtain a diol monomer M1 with the structure as shown in formula II:

formula II

Synthesis of a diacid monomer M2: placing homovanillic acid and 2,2' -dibromo diethyl ether in a certain proportion into a reactor, adding acetonitrile under the stirring condition until reactants are dissolved, stirring and heating the reaction mixture to 75-82 ℃, reacting for 2-5 h, stopping heating, adding cold water into the reaction mixture until insoluble substances are not increased any more, filtering, washing filter residues for 3 times by using cold distilled water, filtering again, drying the filter residues in an oven at 60 ℃ for 2-3 h to obtain a dibasic acid monomer M2 with the structure as shown in formula III:

formula III

(2) Preparation of homovanillic acid-based biomass polyester P

Replacing air in a reactor with nitrogen, putting the diol monomer M1, the diacid monomer M2 and the polycondensation catalyst prepared in the step (1) into a reaction container according to a certain proportion under the protection of nitrogen, stirring and reacting for 5-6 hours at 145-165 ℃, controlling the vacuum degree of a reaction system to be 50-100 Pa, heating the reaction mixture to 200-230 ℃ within 1 hour, continuing to stir and react for 3-4 hours, cooling the reaction mixture to room temperature under the atmosphere of nitrogen, adding chloroform into the reaction mixture until the reaction mixture is dissolved, filtering, adding sufficient methanol into the filtrate until precipitation is not increased, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, and drying in an oven at 70-80 ℃ for 2-3 hours to obtain the biomass polyester P based on the high vanillic acid.

3. The preparation of a homovanillic acid based biomass polyester P according to claim 2, characterized in that: the mass ratio of 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol to ethylene carbonate in step (1) was 1: (1.0-2.0); the mass ratio between homovanillic acid and 2,2' -dibromodiethyl ether was 1: (0.5 to 1.0).

4. The preparation of a homovanillic acid based biomass polyester P according to claim 2, characterized in that: the polycondensation catalyst in the step (2) is a composite catalyst consisting of one or two or three of germanium dioxide, cerium dioxide and aluminum triethoxide, and the dosage of the polycondensation catalyst is 0.10-0.52% of the mass of the dibasic acid monomer M2.

5. The preparation of a homovanillic acid based biomass polyester P according to claim 2, characterized in that: in the step (2), the mass ratio of the dihydric alcohol monomer M1 to the dibasic acid monomer M2 is 1 (1.0-1.2).

6. The use of the polyester P obtained by the preparation method of the high vanillic acid based biomass polyester P according to the claims 2 to 5 is characterized in that the polyester P is used as a high transparent protective film on the surface of a display panel, and the preparation method of the protective film is as follows: mixing a biomass polyester P based on homovanillic acid with 50-80 nm SiO₂Fully mixing and banburying according to the mass ratio of 100 (3-12), and then carrying out a blowing film forming or rolling film forming process to obtain a film of 10-30 mu m, wherein the film is used for preparing a high-transparency protective film of a display panel.

Technical Field

The invention belongs to the field of polymer synthesis. In particular to a structure and a preparation of a homovanillic acid-based biomass polyester P, and the prepared biomass polyester can be used as a base material of a display panel protective film.

Background

With the rapid development of economy and science and technology, people pay more attention to the balance of ecological environment and the sustainable development of resources while paying more attention to the improvement of living standard. In order to deal with the early effect of 'plastic limit' issued and implemented by 'white pollution', the use amount of plastic shopping bags in supermarkets and shopping malls is generally reduced by more than two thirds, and the plastic shopping bags are reduced by about 140 ten thousand tons cumulatively, which is equivalent to the purposes of saving 840 ten thousand tons of petroleum, saving 1200 ten thousand tons of standard coal and reducing 3000 ten thousand tons of carbon dioxide emission. The rise of polyester materials brings convenience to our lives, and polyester film (PET) is a film material which is prepared by taking polyethylene glycol terephthalate as a raw material, preparing a thick sheet by adopting an extrusion method and stretching the thick sheet, and has the characteristics of high tensile strength, good optical performance, high elastic modulus, good toughness, good thermal stability and the like, and also has excellent acid resistance, alkali resistance and air tightness. At present, most of polyester films are applied to the packaging industry, such as food packaging bags, medicines, cigarettes, wines, article packaging bags and the like, and are also partially applied to the field of special films, such as liquid crystal displays, automobile glass films, building decoration films and display protection films. With the progress of science and technology and economy, the usage amount of the polyester film is continuously increased, the polyester film industry has huge development space in China, meanwhile, the environmental awareness of people is increasingly strengthened, and the used materials are developed in the directions of reducing energy consumption, recycling and degrading. Although the polyester lens has relatively good optical performance, the polyester film produced by processing domestic polyester resin generally has the problems of fogging, poor transparency and deep color, and cannot meet the requirements of protective films of high-end glass, displays and the like.

The method reasonably utilizes biomass resources, obtains bio-based monomers and bio-based polymers which can be used for polyester synthesis through a biochemical means is the popular direction of the research of the current novel materials, synthesizes the novel materials based on biomass platform compounds, is an important breakthrough for combining advanced manufacturing industry and emerging industry, is a technology with strategic value for solving the problem of 'neck' and has important significance for promoting the upgrading of the industry. Among the bio-based monomers that are currently common are Ethylene Glycol (EG), lactic acid, 2, 5 furandicarboxylic acid (FDCA). Sachin s. Kuhire^[1]Etc ([ 1)] Kuhire S S ,Ichake A B ,Grau E , et al. Synthesis and Characterization of Partially Bio-Based Polyimides Based on Biphenylene-Containing Diisocyanate Derived from Vanillic Acid[J]European Polymer Journal, 2018, 109:257-264.) 5,5 '-diisocyanato-2, 2', 3,3 '-tetramethoxy-1, 1' -Biphenyl (BDI) is synthesized by taking vanillic acid as a raw material and is subjected to polycondensation reaction with 5 commercially available aromatic dianhydrides to obtain a series of partial bio-based polyimides, wherein the corresponding biomass polyesters have the same physicochemical properties as petroleum-based polymers, but the main components of the bio-based polyimides still come from petroleum resources. The PTA biomass polyester is formed by Polycondensation of Terephthalic Acid (PTA) serving as a diacid monomer and bio-based dihydric alcohol serving as another monomer, but the PTA which can be directly used for polycondensation is prepared by no biochemical means at present, and the main source of the PTA biomass polyester is still petroleum; in addition, the bio-based monomer obtained by the existing biochemical means is used for the synthesis of polyester, and has the problem of poor mechanical property. The existence of these problems causes the mechanical properties of the polyester products obtained by the existing bio-based monomers to be inferior to those of petroleum-based monomers, and the properties of the polyester products are to be improved. For example, PEE, which is not currently commercially available, has great potential to replace PET, but the thermal stability of its monomeric FDCA inhibits its processing and synthesis ^[2]（[2]Research progress of Lilibo, Sukunmi, Lishuang Ring-Furanyl polymers [ J]Petrochemical industry2017,46(08): 1080-.

Disclosure of Invention

In order to solve the problems in the prior art, the invention adopts bio-based renewable chemicals such as homovanillic acid derived from lignin, 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol and the like as raw materials, adopts a Williamson synthesis method and hydroxyethylation of phenolic hydroxyl groups to prepare a novel diol monomer M1 and a diacid monomer M2, and then utilizes a melt polymerization method to synthesize a novel polyester material with good rigid structure and flexible chain structure. The polyester material prepared by the invention has good color and luster, and good light transmission, extensibility and mechanical property, so that the polyester material has good development prospect in the field of high-grade films, such as optical display fields like display protective films and the like.

The invention adopts the following technical scheme:

a homovanillic acid-based biomass polyester P, the structure of which is shown as the following formula:

formula I

In the structural formula, x is 20-130.

The biomass polyester P based on homovanillic acid is characterized in that: the preparation of the biomass polyester P comprises the following steps:

(1) synthesis of monomers

Synthesis of a diol monomer M1: at room temperature, N₂Under protection, 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol with CAS number 1089332-89-7 isAnd ethylene carbonate are put into a reaction container according to a certain proportion, N-dimethylformamide is added and stirred to be dissolved, then potassium carbonate in an amount which is 0.10-0.20 time of that of the ethylene carbonate is added, then the reaction mixture is heated to 150-170 ℃, continuously stirred and reacted for 2-4 hours, and then cooled to room temperature. Then adding 0.10mol/L sodium hydroxide solution into the mixture under stirring until the precipitate is not separated out, filtering, washing the filter residue with distilled water for 2-3 times, and drying in a 50 ℃ oven for 1-2 hours to obtain a diol monomer M1 with the structure as shown in formula II:

formula II

Synthesis of a diacid monomer M2: placing homovanillic acid and 2,2' -dibromo diethyl ether in a certain proportion into a reactor, adding acetonitrile under the stirring condition, stirring until the mixture is dissolved, stirring and heating the reaction mixture to 75-82 ℃, reacting for 2-5 h, stopping heating, adding cold water into the reaction mixture until insoluble substances are not increased any more, filtering, washing filter residues for 3 times by using cold distilled water, filtering again, drying the filter residues in an oven at 60 ℃ for 2-3 h, and obtaining a dibasic acid monomer M2 with the structure as shown in formula III:

formula III

(2) Preparation of homovanillic acid-based biomass polyester P

Replacing air in a reaction system with nitrogen, putting the diol monomer M1, the diacid monomer M2 and the polycondensation catalyst prepared in the step (1) into a reaction container according to a certain proportion under the protection of nitrogen, stirring and reacting for 5-6 hours at 145-165 ℃, controlling the vacuum degree of the reaction system to be 50-100 Pa, heating the reaction mixture to 200-230 ℃ within 1 hour, continuing to stir and react for 3-4 hours, cooling the reaction mixture to room temperature under the atmosphere of nitrogen, adding chloroform into the reaction mixture until the reaction mixture is dissolved, filtering, adding sufficient methanol into the filtrate until precipitation is not increased, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, and drying in an oven at 70-80 ℃ for 2-3 hours to obtain the biomass polyester P based on high vanillic acid.

More preferably, the mass ratio of 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol to ethylene carbonate in the step (1) is 1 (1.0 to 2.0); the mass ratio of homovanillic acid to 2,2' -dibromodiethyl ether is 1 (0.5-1.0).

Preferably, the polycondensation catalyst in the step (2) is one or more composite catalysts composed of germanium dioxide, cerium dioxide and aluminum triethoxide, and the amount of the polycondensation catalyst is 0.10-0.52% of the mass of the dibasic acid monomer M2.

More preferably, in the step (2), the mass ratio of the diol monomer M1 to the diacid monomer M2 is 1 (1.0-1.2).

The invention discloses a use of a high vanillic acid-based biomass polyester P, which is characterized in that the high vanillic acid-based biomass polyester P is used as a high-transparency protective film on the surface of a display panel, and the preparation method of the film is as follows: mixing a biomass polyester P based on homovanillic acid with 50-80 nm SiO₂Fully mixing according to the mass ratio of 100 (3-12), banburying, and performing a blowing film forming or rolling film forming process to obtain a 10-30 mu m film, wherein the film is used for preparing a high-transparency protective film of a display panel.

Advantageous effects

1. The polyester is prepared by adopting 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol, homovanillic acid and other bio-based renewable green chemicals instead of petroleum-based monomers as basic raw materials, so that the problem of shortage of petroleum resources in the future can be partially relieved, and the implementation of national carbon emission reduction, carbon neutralization and national policy is facilitated.

2. The polyester film for the panel protective film belongs to a consumable material, and is extremely easy to throw away as garbage after a user uses the polyester film for a certain time, and is not recycled habitually, but the biomass polyester film product prepared by the method can participate in a natural circulation process after being thrown away, and is easily degraded into water, carbon dioxide and other small molecules by water, sunlight, soil, air and microorganisms in a natural environment.

3. The invention also provides a novel polyester monomer, provides a new idea for the preparation of polyester, and the prepared polyester is rich in a rigid aromatic ring structure and a spiro structure, so that the polyester has better mechanical property and stronger mechanical property, effectively overcomes the defects in the aspects of mechanical property and mechanical property of materials such as polyethylene terephthalate (PET), polylactic acid (PLA), Polycaprolactone (PCL), polybutylene succinate (PBS), Polyhydroxyalkanoate (PHA), polypropylene carbonate, polyvinyl alcohol (PVA), polyethylene carbonate (PEC) and the like, and meets the requirements of the existing market on polyester film products.

4. The high-transparency polyester film prepared by the invention uses high-efficiency catalyst and high-efficiency polycondensation reaction to prepare high-molecular-weight polyester resin, the film forming performance is greatly improved, the problem of fogging of a common film is solved by the processed film, and the prepared high-transparency polyester film can be widely applied to protective films, reflective films, diffusion films, brightness enhancement films and the like of high-grade display screens and glass panels, and has good development prospect.

Detailed Description

The present invention will be further illustrated by the following examples, but the present invention is not limited to these examples. The raw materials in the invention are all conventional and commercially available. In order to clearly understand the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following embodiments. The specific examples described herein refer to specific data only to illustrate the invention and are not meant to limit the invention.

The structure of the monomers and polyesters prepared in the examples was determined: the determination is carried out by adopting a Bruker Avance DMX600 nuclear magnetic resonance instrument of Germany Bruker spectral instruments and a VERTEX70 Fourier transform infrared spectrometer of Germany Bruker spectral instruments;

testing of mechanical properties of the polyesters in the examples: the tensile property test adopts a Z005 type universal material testing machine of Zwick company in Germany and tests according to GB/T1040.2-2006; the bending performance test is carried out according to GB/T9341-2008 standard by adopting a Z005 type universal material testing machine of Zwick company in Germany; the impact performance test adopts a HIT50J model simply supported beam impact tester of Zwick company in Germany to test according to GB/T1043.1-2008;

transparency test of polyester film in examples: cutting the polyester film into samples of 50mm multiplied by 50mm, making 3 samples in each group, and measuring the light transmittance and the haze of the adhesive film by using a photoelectric haze meter (WGW, Shanghai precision science instrument, Inc.) according to GB/T2410-1980;

determination of molecular weight and distribution thereof: dissolving the polymer product in Tetrahydrofuran (THF), and measuring by using a Waters 2412 type gel permeation chromatograph;

results were averaged over three test specimens.

Yield =100% x actual amount of target product/theoretical amount of target product produced.

Example 1

Synthesis of diol monomer M1, N at room temperature₂9.00g (0.04 mol) of 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol having CAS number 1089332-89-7 and 6.90g (0.08 mol) of ethylene carbonate were charged into a reaction vessel, 100ml of N, N-Dimethylformamide (DMF) was added and dissolved with stirring, 1.83g (0.01 mol) of potassium carbonate was added as a catalyst, and the reaction was stirred at 160 ℃ for 3 hours, and after completion of the reaction, the reaction was cooled to room temperature. Then adding 50.0mL (0.10 mol/L) of sodium hydroxide solution under stirring, separating out white insoluble substances, filtering, washing the filter residue with 200mL of distilled water twice, and drying the filter residue in an oven at 50 ℃ for 1-2 h to obtain a diol monomer M1The yield thereof was found to be 86.00%.

Example 2

Synthesis of a diacid monomer M2: 1.82g (0.01 mol) of homovanillic acid and 50ml of acetonitrile are placed in a reactor, 2.31g (0.01 mol) of 2,2' -dibromodiethyl ether are slowly added with stirringStirring and reacting for 5h at 110 ℃ in a reaction vessel, stopping heating, then adding 500ml of cold distilled water into the reaction mixture, precipitating out insoluble substances, filtering, washing the filter residue with distilled water for 3 times, filtering again, drying the filter residue in an oven at 60 ℃ for 2-3 h to obtain a dibasic acid monomer M2, namelyThe yield thereof was found to be 85.00%.

Example 3

Replacing air in a reaction system with nitrogen, sequentially putting 3.14g (0.01 mol) of diol monomer M1 and 4.34g (0.01 mol) of diacid monomer M2 into a reaction vessel under the protection of nitrogen, adding 0.006g of germanium dioxide, stirring and reacting for 5 hours at 160 ℃, controlling the vacuum degree of the reaction system to be 80Pa, heating the reaction mixture to 210 ℃ within 1 hour, continuing to stir and react for 3.0 hours, cooling the reaction mixture under the nitrogen atmosphere, adding chloroform into the reaction mixture until the chloroform is dissolved, filtering, adding enough methanol into the filtrate until precipitation does not increase, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, and then placing the filter residue into an oven at 75 ℃ for drying for 3 hours to obtain polyester P1, wherein the number-average molecular weight is 54000g/mol, and the yield is 85.53%.

Preparation of a highly transparent protective film for a display panel: 100g of polyester P1 was mixed with 5g of SiO having an average particle diameter of 50nm₂And after fully mixing and banburying, obtaining a 10 mu m thin film through a calendering film forming process, wherein the thin film is used for preparing a high-transparency protective film of a display panel.

Example 4

Replacing air in a reaction system with nitrogen, sequentially putting 3.14g (0.01 mol) of diol monomer M1 and 4.78g (0.011 mol) of diacid monomer M2 into a reaction container under the protection of nitrogen, adding 0.010g of cerium dioxide, stirring and reacting for 6 hours at 165 ℃, controlling the vacuum degree of the reaction system to be 90Pa, heating the reaction mixture to 200 ℃ within 1 hour, continuing to stir and react for 3.0 hours, cooling the reaction mixture under the nitrogen atmosphere, adding chloroform into the reaction mixture until the chloroform is dissolved, filtering, adding enough methanol into the filtrate until precipitates are not increased, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, and then placing the filter residue into an oven at 70 ℃ for drying for 2.0 hours to obtain polyester P2, wherein the number-average molecular weight is 52600g/mol, and the yield is 86.49%.

Preparation of a highly transparent protective film for a display panel: 100g of polyester P2 was mixed with 5g of SiO having an average particle diameter of 55nm₂And after fully mixing and banburying, obtaining a film of 15 mu m by a blow molding film forming process, wherein the film is used for preparing a high-transparency protective film of the display panel.

Example 5

Replacing air in a reaction system with nitrogen, sequentially putting 3.14g (0.01 mol) of diol monomer M1 and 5.20g (0.012 mol) of diacid monomer M2 into a reaction vessel under the protection of nitrogen, adding 0.013g of aluminum triethoxide, stirring and reacting at 155 ℃ for 5.5 hours, controlling the vacuum degree of the reaction system to be 95Pa and within 1 hour, heating the reaction mixture to 225 ℃, continuing to stir and react for 3.5 hours, cooling the reaction mixture under the atmosphere of nitrogen, adding chloroform into the reaction mixture until the chloroform is dissolved, filtering, adding enough methanol into the filtrate until precipitation is not increased, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, and drying in an oven at 78 ℃ for 3.0 hours to obtain polyester P3, wherein the number-average molecular weight is 49600g/mol, and the yield is 87.26%.

Preparation of a highly transparent protective film for a display panel: 100g of polyester P3 was mixed with 7g of SiO having an average particle diameter of 60nm₂And after fully mixing and banburying, obtaining a film of 20 mu m by a blow molding film forming process, wherein the film can be used for preparing a high-transparency protective film of a display panel.

Example 6

The air in the reaction system was replaced with nitrogen, 3.14g (0.01 mol) of a diol monomer M1 and 4.34g (0.01 mol) of a diacid monomer M2 were charged into a reaction vessel in this order under the protection of nitrogen, 0.015g of binary catalyst (0.006 g of germanium dioxide and 0.009g of cerium dioxide) is added, the mixture is stirred and reacted for 5.0 hours at the temperature of 145 ℃, then controlling the vacuum degree of the reaction system to be 95Pa, heating the reaction mixture to 220 ℃ within 1h, continuously stirring and reacting for 4 hours, the reaction mixture was cooled under nitrogen atmosphere, then chloroform was added to the reaction mixture until dissolved, filtered, adding sufficient methanol into the filtrate until precipitate does not increase, filtering, washing the obtained residue with cold methanol for 3 times, filtering again, drying in 80 deg.C oven for 2 hr, polyester P4 was obtained with a number average molecular weight of 55500g/mol, yield 86.39%.

Preparation of a highly transparent protective film for a display panel: 100g of polyester P4 was mixed with 9g of SiO having an average particle diameter of 64nm₂And after fully mixing and banburying, obtaining a film of 25 mu m by a calendering film forming process, wherein the film is used for preparing a high-transparency protective film of a display panel.

Example 7

Replacing air in a reaction system with nitrogen, sequentially putting 3.14g (0.01 mol) of diol monomer M1 and 4.77g (0.011 mol) of diacid monomer M2 into a reaction vessel under the protection of nitrogen, adding 0.019g of binary catalyst (0.012 g of germanium dioxide 0.007g of aluminum triethoxide), stirring and reacting at 145 ℃ for 5.5 hours, controlling the vacuum degree of the reaction system to be 90Pa within 1 hour, heating the reaction mixture to 210 ℃, continuing to stir and react for 3.5 hours, cooling the reaction mixture under the atmosphere of nitrogen, adding chloroform into the reaction mixture until the chloroform is dissolved, filtering, adding sufficient methanol into the filtrate until precipitation is not increased, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, and drying in an oven at 70 ℃ for 3 hours to obtain the polyester P5, wherein the number-average molecular weight is 57700g/mol, and the yield is 89.46%.

Preparation of a highly transparent protective film for a display panel: 100g of polyester P5 was mixed with 10g of SiO having an average particle diameter of 70nm₂And after fully mixing and banburying, obtaining a 27 mu m film through a blow molding film forming process, wherein the film is used for preparing a high-transparency protective film of the display panel.

Example 8

Replacing air in a reaction system with nitrogen, sequentially putting 3.14g (0.01 mol) of diol monomer M1 and 5.20g (0.012 mol) of diacid monomer M2 into a reaction vessel under the protection of nitrogen, adding 0.021g of ternary catalyst (0.005 g of germanium dioxide, 0.008g of cerium dioxide and 0.008g of aluminum triethoxide), stirring and reacting at 155 ℃ for 5.0 h, then controlling the vacuum degree of the reaction system within 100Pa and 1h, heating the reaction mixture to 230 ℃, continuing to stir and react for 3.0 h, cooling the reaction mixture under nitrogen atmosphere, then adding chloroform into the reaction mixture to dissolve, filtering, adding enough methanol into the filtrate until precipitation does not increase, filtering, washing the obtained filter residue with cold methanol for 3 times, filtering again, then placing in an oven at 70 ℃ for drying for 2.0 h to obtain polyester P6 with the number average molecular weight of 48900g/mol, the yield thereof was found to be 85.12%.

Preparation of a highly transparent protective film for a display panel: 100g of polyester P6 was mixed with 10g of SiO having an average particle diameter of 75nm₂And after fully mixing and banburying, obtaining a film of 30 mu m by a calendering film forming process, wherein the film is used for preparing a high-transparency protective film of a display panel.

TABLE 1 polyester P synthesized according to the examples₁~P₆Mechanical properties of

Note: m_nAnd M_n ¹The number average molecular weight before degradation and the number average molecular weight after one year in PBS buffer solution

[3] Lvtong Jian, Easturg, Zhouyou, Wushuang, segmented Wei, Zhanglin, preparation and performance research of PET/GF composite material [ J ] engineering plastics application, 2005, 2005(9):6-9.

TABLE 2 light transmittance of polyester films obtained by processing the polyesters P1-P6 synthesized in the examples

[4] Zhanghong, Yuan 29667, Lufengjie, Yangyang, Shuqiang, preparation and research of Si-containing optical anti-reflection polyester film [ J ]. New chemical material, 2013,41(08):33-35.

[5] Dingbei, Zhangxiahong, neck Shanlin, Wangting masturbation, Wang Yinye leaf, preparation of polyurethane adhesive for high transparent composite film [ J ] packaging engineering, 2009,30(2):36-38.

From the above examples and the related data, it can be seen that the 4- (5- (hydroxymethyl) -5-methyl-1, 3-dioxane) -2-methoxyphenol and homovanillic acid are used as main raw materials, the mechanical properties (tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength) of the polyester are greatly improved compared with that of ethylene terephthalate (PET), the adopted multi-component composite catalyst has high catalytic efficiency and small dosage, and the prepared polyester has high transparency and light color, wherein when GeO is used as the catalyst₂When the weight ratio of the prepared polyester P3 to the aluminum triethoxide is 1:1, the prepared polyester P3 has the highest transparency, the light transmittance can reach 97.5 percent, the haze is reduced to 6.2 percent, and the nano SiO 2₂The addition of the polyester can further improve the mechanical property and the glossiness of the polyester material, and can weaken the fogging phenomenon of the material, so that the polyester material meets the requirements of the existing market on the polyester. Because the main raw materials are all derived from biomass-lignin, the degradation performance of the polyester material is greatly improved.

In conclusion, the main part of the synthesis of the existing bio-based polyester material still uses petroleum-based raw materials, more catalysts are needed, the catalytic efficiency is low, the obtained polyester has dark color, and the mechanical property, the thermal property and the processing property of the polyester are poor, so that the requirements on various material properties in practical application are difficult to meet. Aiming at the problems in the prior art, the invention provides a homovanillic acid-based biomass polyester, a preparation method and application thereof. On one hand, the raw material for preparing the biomass polyester is derived from biomass resources, so the prepared polyester can participate in a natural circulation process after being discarded; on the other hand, the prepared biomass polyester is rich in a large amount of rigid aromatic ring structures and spiro structures, so that the polyester material has better mechanical properties, the polyester prepared by adopting the multi-element composite catalyst consisting of germanium dioxide, cerium dioxide and aluminum triethoxide or the combination of the germanium dioxide, the cerium dioxide and the aluminum triethoxide has high transparency and low yellowness, and can be used as a thin film after being stretched, so that the biomass polyester can be widely applied to a protective film of a high-grade display screen. As mentioned above, the high vanillic acid-based polyester prepared by the invention has good market prospect.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention. It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.