A kind of polyarylate based on recycling of bisphenol, its high heat resistance high light transmission film and preparation method thereof

Abstract

The application belongs to the field of polymer synthesis, and particularly relates to a kind of polyarylate based on recycled bisphenol, its high heat resistance and high light transmission film and a preparation method thereof. The application adopts a segmented temperature control interfacial polymerization method, and makes recycled bisphenol monomers containing impurities and aromatic diformyl chloride perform interfacial polymerization reaction in an organic solvent and water system to obtain high-performance polyarylate. The application does not need to refine recycled bisphenol monomers with high energy consumption, and turns disadvantages into advantages, simplifies the process and reduces the cost. The obtained polyarylate and the film prepared therefrom have high heat resistance, excellent mechanical strength and processability, and are suitable for high-end fields such as high-frequency information and light transmission.

Description

Technical Field

[0001] This invention belongs to the field of polymer synthesis, specifically relating to a polyarylate based on recycled bisphenols, its high heat resistance and high light transmittance film, and its preparation method. Background Technology

[0002] With global warming and the growing demand for green and low-carbon development, the call and requirements for the recycling of traditional bulk waste polymers are increasing. Polyester, as an engineering plastic, possesses good thermal, mechanical, and processing properties. Traditional polyesters mainly include PET (glass transition temperature 69℃, melting point 255-260℃), PBT (glass transition temperature 36-49℃, melting point 220-225℃), and polycarbonate (PC, glass transition temperature approximately 145-150℃), which are widely used in industrial production and daily life, accounting for a significant proportion of waste plastics. Therefore, their resource recycling is particularly important. Traditional polyester recycling often employs mechanical and physical methods, but after multiple physical recycling processes, varying degrees of thermal and mechanical degradation occur, limiting the number of recycling cycles. Another method for polyester recycling involves chemical degradation to recover monomers, which are then repolymerized to achieve the ultimate goal of green and sustainable recycling. Current depolymerization processes and technologies suffer from problems such as low depolymerization efficiency and residual impurities (antioxidants, end-capping agents, colorants, etc.), resulting in low purity of the degradation products. This makes it difficult to effectively recycle plastic materials, often requiring multiple purification processes (significantly increasing energy consumption and costs) to obtain monomers with higher purity to meet subsequent production needs.

[0003] Polyarylates (PAR) with a long-term operating temperature ≥150℃ are mainly formed by the condensation polymerization of diacid (or diacid chloride) and bisphenol. They can be used to make high-performance engineering plastic parts, fibers and films. Their heat resistance and mechanical properties are significantly improved compared to traditional polyesters such as PET and PC. They are widely used in high-frequency electronic information and optical transmission fields. The monomers used, especially bisphenol monomers, often have special structures and high prices, and are high-value monomers. From a commercial operation perspective, it is necessary to recycle and even upgrade their use. Summary of the Invention

[0004] To address the aforementioned deficiencies, this invention provides a method for preparing polyarylates based on recycled bisphenols, and a high-heat-resistant and high-transmittance polyarylate film prepared from the polyarylate. The resulting high-heat-resistant and high-transmittance polyarylate film exhibits excellent heat resistance, good mechanical strength, excellent melt processing flowability, and light transmittance. It can be used for precision injection molding to prepare high-performance and functional parts, and has broad application prospects.

[0005] Specifically, in a first aspect, the present invention provides a method for preparing polyarylates using recycled bisphenol, comprising the following steps: in a mixture of organic solvent and water, in the presence of a catalyst and a base, causing an impurity-containing recycled bisphenol monomer to undergo an interfacial polymerization reaction with an aromatic dicarboxylic acid chloride.

[0006] The interfacial polymerization reaction is carried out using a segmented temperature control method:

[0007] First, the first stage reaction is carried out at the first temperature to generate polyarylate prepolymer;

[0008] Then, the reaction system is heated to a second temperature to carry out the second stage reaction, so that the impurities in the recovered bisphenol monomer participate in the end-capping reaction to obtain polyarylate;

[0009] The first temperature is -15°C to 5°C, and the second temperature is 5°C to 30°C.

[0010] In a specific implementation, the first temperature can be -15℃, -10℃, -5℃, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, or a temperature range between any two of the above values.

[0011] In a specific implementation, the second temperature can be 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 25°C, 30°C, or a temperature range between any two of the above values, preferably 17°C to 30°C, more preferably 18°C ​​to 30°C, more preferably 19°C to 30°C, more preferably 20°C to 30°C, and most preferably 25°C to 30°C.

[0012] In a specific implementation plan, the recycled bisphenol monomer is derived from the chemical degradation of waste polyester materials, and the impurities include the end-capping agents and / or antioxidants originally present in the waste polyester materials.

[0013] In a specific implementation plan, the method for preparing the recovered bisphenol monomer includes the following steps: in the presence of a degradation catalyst and an alcohol solvent, waste polyester is subjected to a degradation reaction in an inert gas at 50-210°C. After the reaction is completed, the temperature is lowered to precipitate crude bisphenol. After solid-liquid separation, washing, and drying, recovered bisphenol monomer containing impurities is obtained.

[0014] In a specific implementation plan, the purity of the recovered bisphenol monomer in step (1) is above 98%, and the recovered bisphenol monomer does not need to undergo a purification step to remove the impurities.

[0015] In a specific implementation, the method further includes a purification step after the interfacial polymerization reaction is completed: the reaction mixture is allowed to stand and separate into layers, the aqueous phase is separated, the organic phase is washed with deionized water, and the washing is repeated 2 to 6 times to obtain a purified polyarylate resin solution.

[0016] In a specific implementation, the method further includes a curing and granulation step: adding a diluent and an antioxidant to the purified polyarylate resin solution, mixing them evenly, and then feeding them into an atomizing granulation tower for curing and granulation, controlling the temperature of the atomizing granulation tower to be 20°C to 180°C and the vacuum degree to be -0.05MPa to -0.095MPa.

[0017] In a specific implementation plan, the structural formula of the recovered bisphenol monomer is:

[0018] .

[0019] In a specific implementation scheme, the structural formula of the aromatic dicarboxylic acid chloride is:

[0020] .

[0021] In a specific implementation scheme, the organic solvent is any one of 1,2-dichloroethane, 1,1-dichloroethane, 1,1,2,2-tetrachloroethane, chloromethane, dichloromethane, chloroform, carbon tetrachloride, cyclohexane, cyclohexanone, chlorobenzene, m-dichlorobenzene, 1,2,4-trichlorobenzene, or chloronaphthalene.

[0022] In a specific implementation scheme, the catalyst is at least one selected from tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, tetraethylammonium bromide, hexadecyltrimethylammonium chloride, dioctadecyldimethylammonium chloride, sodium gluconate, sodium dioctylsuccinate, sodium aziridine triacetate, sodium sorbate, sodium ethylenediaminetetraacetate, sodium ethylenediaminetetramethylidene phosphate, sodium glycocholate, sodium benzenesulfonate, sodium p-methylbenzenesulfonate, sodium alginate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, dodecyl dimethyl betaine, PEG-200, PEG-400, PEG-600, PEG-800, 12-crown-4, 15-crown-5, benzo15-crown-5, 18-crown-6, 21-crown-7, Tween 80, and Span 60.

[0023] In a specific implementation scheme, the alkali is any one of lithium hydroxide, sodium hydroxide, calcium hydroxide, potassium hydroxide, barium hydroxide, aluminum hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, barium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, barium bicarbonate, ammonia, trimethylamine, triethylamine, tri-tert-butylamine, pyridine, or piperazine.

[0024] In a specific implementation, the waste polyester is polycarbonate or polyarylate.

[0025] In specific implementation schemes, the degradation catalyst is TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene), TBD / HCl, TBD / HBr, TBD / HCOOH, TBD / CH3COOH, TBD / CH3CH2COOH, TBD / CH3OCH2COOH, MTBD (7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene), MTBD / HCl, MTBD / HBr, MTBD / HCOOH, MTBD / CH3COOH, MTBD / CH3CH2COOH, MTBD / CH3OCH2COOH, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), DBU / HCl, DBU / HBr, DBU / HCOOH, DBU / CH3COOH, DBU / CH3CH2COOH, DBU / CH3OCH2COOH, MDBU (1-methyl-1,8-diazaspiro[5.5]undecane), MDBU / HCl, MDBU / HBr, MDBU / HCOOH, MDBU / CH3COOH, MDBU / CH3CH2COOH, MDBU / CH3OCH2COOH, 1-butyl-3-methylimidazolium hydrochloride / anhydrous cobalt chloride ([BMIM]2[CoCl4]), zinc acetate, sodium acetate, magnesium acetate, zinc carbonate, potassium carbonate, potassium tert-butoxide, sodium ethoxide, tetrabutylammonium acetate, tetrabutylammonium hydroxide, potassium hydroxide, aluminum isopropoxide.

[0026] In a specific implementation plan, the amount of the degradation catalyst used is 0.1-10% of the weight of the waste polyester material.

[0027] In a specific implementation scheme, the alcohol solvent is any one of methanol, ethanol, propanol, tert-butanol, isopropanol, ethylene glycol, and propylene glycol.

[0028] In a specific implementation plan, the amount of alcohol solvent used is 2-12 times the weight of the waste polyester material.

[0029] In a specific implementation, the diluent is selected from chloroform or dichloromethane.

[0030] In a specific implementation scheme, the materials used in the method are in the following weight proportions: 200-310 parts by weight of recovered bisphenol monomer, 203-455 parts by weight of aromatic dicarboxylic acid chloride, 0.02-10 parts by weight of catalyst, 80-200 parts by weight of alkali, 500-2500 parts by weight of water, and 300-4000 parts by weight of organic solvent.

[0031] In a specific implementation, the method includes: adding the recovered bisphenol monomer, catalyst and alkali to water, stirring and dissolving at -10 to 20°C to obtain an aqueous solution, dissolving aromatic dicarboxylic acid chloride in an organic solvent, and adding the obtained aromatic dicarboxylic acid chloride solution dropwise to the aqueous solution to carry out an interfacial polymerization reaction.

[0032] In a specific implementation plan, the reaction time of the first stage reaction is 1 to 12 hours; the reaction time of the second stage reaction is 0.5 to 5 hours.

[0033] In a second aspect, the present invention provides a polyarylate prepared by the method described herein.

[0034] In a third aspect, the present invention provides a high heat-resistant and high light-transmitting polyarylate film, which is obtained by melt processing and stretching of the polyarylate as described herein.

[0035] In a specific implementation, the polyaryl ester film is prepared by mixing the polyaryl ester with a light stabilizer and granulating it by twin-screw extrusion; drying the granules and then casting and extruding them into a film; and then preheating the film at 120°C to 280°C and then biaxially stretching it into a thin film.

[0036] In a specific implementation, the temperature of the cast extrusion is 290-350℃, the feeding speed is 0.05-5kg / min, and the screw speed is 20-250r / min.

[0037] In a specific implementation, the biaxial stretching includes first stretching laterally by 2 to 20 times at a stretching rate of 10 to 300 mm / min, and then stretching longitudinally by 2 to 20 times.

[0038] In a specific implementation, the film has a transmittance of more than 85% at a wavelength of 450 nm, a tensile strength of more than 55 MPa, and a glass transition temperature of more than 190 °C for the polyarylate.

[0039] In a preferred embodiment, the starting material of the high heat-resistant and high light-transmitting polyarylate consists of the following components: 200-310 parts by weight of recycled bisphenol monomer, 203-455 parts by weight of aromatic dicarboxylic acid chloride, 0.02-10 parts by weight of catalyst, 80-200 parts by weight of alkali, 500-2500 parts by weight of water, 300-4000 parts by weight of organic solvent, 0-0.5 parts by weight of antioxidant, and 0.05-1 parts by weight of light stabilizer.

[0040] In a preferred embodiment, the method for preparing the high heat-resistant and high light-transmitting polyarylate film includes the following steps:

[0041] (1) Preparation of crude polyarylates based on the recycling of bisphenol

[0042] 200-310 parts of recovered bisphenol monomer, 0.02-20 parts of catalyst, and 80-200 parts of alkali are sequentially added to a reactor containing 500-2500 parts of water and stirred at -10-20℃ to dissolve. Then, 203-455 parts of aromatic dicarboxylic acid chloride are dissolved in a dissolving vessel containing 300-4000 parts of organic solvent. The acyl chloride solution in the dissolving vessel is then added dropwise to the above reactor. Utilizing the solubility of the recovered bisphenol and its contained end-capping agents and antioxidants at different temperatures, the polymerization is carried out in two stages. First, the reaction is stirred at -15-5℃ for 1-12 hours to obtain a high molecular weight polyarylate resin with active end groups. Then, the reactor temperature is raised to 5-30℃ and the reaction is continued with stirring for 0.5-5 hours. The higher temperature allows the end-capping agent in the recovered bisphenol to dissolve and participate in the end-capping reaction, thus obtaining crude polyarylate based on recycled bisphenol.

[0043] (2) Purification of polyarylates based on recycling bisphenols

[0044] After the crude polyarylate mixture is allowed to stand and separate into layers, the aqueous layer is removed. Then, 150-2000 parts of deionized water are added to the reaction vessel for stirring, washing, and standing to separate into layers. The aqueous layer is removed. This process is repeated at least 2-6 times to obtain a purified low-salt polyarylate resin solution.

[0045] (3) Curing and granulation of polyarylates based on recycled bisphenol

[0046] Add 0-1000 parts of organic solvent to the purified low-salt polyarylate resin solution for dilution, and add 0-0.5 parts of antioxidant and stir evenly. The homogenized solution is sent to the atomization and granulation tower for solidification and granulation through a metering pump. The temperature of the atomization and granulation tower is controlled at 20-180℃ and the vacuum degree is -0.05~-0.095MPa. Further, the solid material obtained after solidification and granulation in step (3) is transported to the finished product workshop for use through pipeline. The solvent vapor is collected in the solvent recovery tank after condensation and recycled.

[0047] (4) Preparation of high heat-resistant and high light-transmitting polyarylate films based on recycled bisphenol

[0048] 1000 parts by weight of recycled bisphenol high heat-resistant and high light-transmitting polyarylate and 0.05-1 parts by weight of light stabilizer were granulated by twin-screw extrusion to obtain resin granules. The dried granules were then extruded and cast in a casting machine to prepare films with a thickness of 0.02-2 mm. The processing temperature of the casting machine was 290-350℃, the feeding speed was 0.05-5 kg / min, and the screw speed was 20-250 r / min. The films were then clamped in a biaxial stretching machine and preheated with hot air at 120-280℃ for 1-10 min. After preheating, the films were first stretched laterally by 2-20 times at a stretching rate of 10-300 mm / min, and then stretched longitudinally by 2-20 times to prepare a film with uniform thickness.

[0049] The beneficial effects of this invention are:

[0050] 1. The alcoholysis catalytic method used in this invention has high degradation efficiency, and the monomer can be obtained with high purity by solid-liquid separation and simple washing. The purification process is simple.

[0051] 2. The polyarylate resin polymerization method used in this invention adopts a medium-low temperature interfacial polymerization method, which has a simple process, mild conditions, and is easy to control. In the entire reaction process, no other harmful substances are generated except for the by-product salt, making it green and environmentally friendly.

[0052] 3. The polymerization process adopts a segmented temperature control method, which makes full use of the solubility difference of impurities in the recovered bisphenol monomer at different temperatures. There is no need to refine and separate the small amount of impurities in the recovered bisphenol monomer, which can be used to produce high molecular weight polyarylate resin. At the same time, the small amount of end-capping agent and antioxidant remaining in the recovered bisphenol monomer can be fully utilized, which improves the overall stability of the resin and significantly reduces the cost of bisphenol recovery and polyarylate production.

[0053] 4. The static chromatography water washing method used in this invention has high desalination and impurity removal efficiency, which can be completed in one device, reducing multiple material transfers and solid-liquid separation of moving equipment in the traditional salt washing process, and greatly reducing energy consumption in the product washing process.

[0054] 5. The integrated atomization, curing and granulation process used in this invention can completely separate the solvent and polymer resin in one step, resulting in high resin purity, high solvent recovery rate and efficiency, short process, reduced production costs, and improved product market competitiveness.

[0055] 6. This type of polymer can be used in special engineering plastics and high-performance polymer composite materials, as well as in the preparation of heat-resistant and high-transmittance components and products. It is especially suitable for high-frequency electronic information and optical transmission fields and has broad application prospects. Attached Figure Description

[0056] Figure 1 The image shows the infrared spectrum of the resin obtained in Example 1. U-100 is a commercially available polyarylate control.

[0057] Figure 2 The NMR spectrum is shown for the resin obtained in Example 1.

[0058] Figure 3 The transmittance of the thin film obtained in Example 1 at different wavelengths is given.

[0059] Figure 4 The image shows the infrared spectrum of the resin obtained in Example 2. PAR310-100: a polyarylate prepared from fresh cyclohexylbisphenol monomer; r-PAR310-100: a polyarylate prepared from recycled cyclohexylbisphenol monomer.

[0060] Figure 5 The NMR spectrum is shown for the resin obtained in Example 2.

[0061] Figure 6 The transmittance of the thin film obtained in Example 2 at different wavelengths is given.

[0062] Figure 7 This is a photograph of the thin film obtained in Comparative Example 2.

[0063] Figure 8 The image shows the DSC curve of the resin obtained in Comparative Example 3. Detailed Implementation

[0064] To achieve efficient degradation and high-quality recycling of waste polyarylates, this invention employs catalytic alcoholysis, significantly improving the degradation conversion rate and bisphenol monomer yield. Simultaneously, a programmed segmented temperature control method is used. This not only avoids the impact of minor impurities on the molecular weight of the secondary polymerization resin during conventional polyester degradation and bisphenol recovery processes, but also fully utilizes minor impurities such as end-capping agents and antioxidants, incorporating them into polymerization and end-capping during the second-stage heating process. This enhances product stability and reduces the need for additives in subsequent polyarylate processing, thus lowering costs. The result is a high-heat-resistant, high-transmittance polyarylate and its film.

[0065] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0066] Example 1

[0067] (1) Recovery of bisphenol monomer

[0068] The recycled polycarbonate optical discs were sorted, cleaned, crushed, and dried. Then, 1 kg of the collected discs was added to a degradation reactor along with 5 g of TBD / HCl catalyst and 5 L of methanol. After nitrogen purging, the reactor was sealed, and the mixture was stirred and heated to 120°C for 3 hours for degradation. After the reaction, the mixture was cooled to precipitate crude bisphenol A (BPA). The crude BPA was filtered, washed with water, decolorized with activated carbon, and vacuum dried to obtain the recovered bisphenol A (BPA) monomer (containing a small amount of end-capping agents from the original waste plastics, requiring no high-energy deep refining; its purity reached 98.8%, as shown in the NMR spectrum). Figure 1 (as shown)

[0069] (2) Preparation of high heat-resistant crude polyarylate based on recycling bisphenol

[0070] 228.8g of recovered BPA monomer, 1g of tetrabutylammonium bromide, and 80g of lithium hydroxide were sequentially added to a reactor containing 1000g of water and stirred at 0°C to dissolve. Then, 101.5g of terephthaloyl chloride and 101.5g of isophthaloyl chloride were dissolved in a dissolving vessel containing 1800g of chloroform. The acyl chloride solution in the dissolving vessel was then added dropwise to the above reactor. Utilizing the solubility of the recovered bisphenol and its impurities such as end-capping agents and antioxidants at different temperatures, the polymerization was carried out in two stages. First, the reaction was stirred at 5°C for 5 hours to obtain a high molecular weight polyarylate resin with active end groups. Then, the reactor temperature was raised to 25°C and the reaction was continued with stirring for 0.5 hours. The higher temperature allowed the end-capping agents in the recovered bisphenol to dissolve and participate in the end-capping reaction, thus obtaining a high-heat-resistant crude polyarylate based on recycled bisphenol.

[0071] (3) Purification of high heat-resistant polyarylates based on recycling bisphenol

[0072] After allowing the crude polyarylate mixture to stand and separate into layers, the aqueous layer was removed. Then, 500g of demineralized water was added to the reactor for stirring, washing, and allowing to stand and separate into layers. The aqueous layer was then removed. This washing cycle was repeated three times to obtain a purified low-salt polyarylate resin solution. Infrared and NMR spectra are shown below. Figure 1 , Figure 2 As shown, its intrinsic viscosity is 0.53 and its glass transition temperature is 194.6℃.

[0073] (4) Curing and granulation of high heat-resistant polyarylates based on recycled bisphenol

[0074] 1000g of chloroform was added to the purified low-salt polyarylate resin solution for dilution, and 0.02g of antioxidant S-9228 was added and stirred evenly. The homogenized solution was then sent to the atomization and granulation tower for solidification and granulation through a metering pump. The temperature of the atomization and granulation tower was controlled at 60℃ and the vacuum degree was -0.095MPa.

[0075] (5) Preparation of high heat-resistant and high light-transmitting polyarylate films based on recycled bisphenol

[0076] 1000g of high-heat-resistant polyarylate based on recycled bisphenol and 0.05g of light stabilizer 2-(2'-hydroxy-5'-methylphenyl)benzotriazole were granulated by twin-screw extrusion to obtain resin granules. The dried granules were then extruded and cast in a casting machine to prepare a film with a thickness of 0.02mm. The casting machine temperature was 310℃, the feed rate was 0.1kg / min, and the screw speed was 30r / min. The film was then clamped in a biaxial stretching machine, preheated with hot air at 280℃ for 1 min, and then stretched horizontally by 2 times and then longitudinally by 2 times at a stretching rate of 300mm / min to prepare a film of uniform thickness. The transmittance at 450nm was measured to be 87.7% (see...). Figure 3 The tensile strength is 67.2 MPa.

[0077] Example 2

[0078] (1) Recovery of bisphenol monomer

[0079] The recycled Unitika T-200 high heat-resistant polyarylate plastic from Japan was sorted, cleaned, crushed, and dried. Then, 1 kg of this recycled material was added to a degradation reactor along with 1 g of MDBU / CH3COOH catalyst and 8 L of ethanol. After nitrogen purging, the reactor was sealed, and stirring was initiated to raise the temperature to 180°C. o C degradation reaction for 12 hours; after the reaction, cooling was performed to precipitate crude cyclohexylbisphenol. The crude bisphenol was filtered and separated, then washed with water, decolorized with activated carbon, and vacuum dried to obtain the recovered cyclohexylbisphenol monomer (containing a small amount of end-capping agents from the original waste plastics, no need for high-energy deep purification, and its purity reached 99.1%).

[0080] (2) Preparation of high heat-resistant crude polyarylate based on recycling bisphenol

[0081] 312.8g of recovered cyclohexylbisphenol monomer, 0.1g of 15-crown-5, and 82g of sodium hydroxide were sequentially added to a reactor containing 2000g of water and stirred at 5°C to dissolve. Then, 60.9g of terephthaloyl chloride and 142.1g of isophthaloyl chloride were dissolved in a dissolving vessel containing 2200g of dichloromethane. The acyl chloride solution from the dissolving vessel was then added dropwise to the above reactor. Utilizing the solubility of the recovered bisphenol and its impurities such as end-capping agents and antioxidants at different temperatures, the polymerization was carried out in two stages. First, the reaction was stirred at 3°C ​​for 6 hours to obtain a high molecular weight polyarylate resin containing active end groups. Then, the reactor temperature was raised to 30°C and the reaction was continued for 1 hour. The higher temperature allowed the end-capping agents in the recovered bisphenol to dissolve and participate in the end-capping reaction, thus obtaining a high-heat-resistant crude polyarylate based on recycled bisphenol.

[0082] (3) Purification of high heat-resistant polyarylates based on recycling bisphenol

[0083] After allowing the crude polyarylate mixture to stand and separate into layers, the aqueous layer was removed. Then, 1100g of demineralized water was added to the reactor for stirring, washing, and allowing to stand and separate into layers. The aqueous layer was then removed. This washing cycle was repeated twice to obtain a purified low-salt polyarylate resin solution. Infrared and NMR spectra are shown below. Figure 4 , Figure 5 As shown, its intrinsic viscosity was 0.56 and its glass transition temperature was 269.6℃.

[0084] (4) Curing and granulation of high heat-resistant polyarylates based on recycled bisphenol

[0085] 600g of dichloromethane was added to the purified low-salt polyarylate resin solution for dilution, and 0.1g of antioxidant 1076 was added and stirred evenly. The homogenized solution was then sent to the atomization and granulation tower for solidification and granulation through a metering pump. The temperature of the atomization and granulation tower was controlled at 30℃ and the vacuum degree was -0.09MPa.

[0086] (5) Preparation of high heat-resistant and high light-transmitting polyarylate films based on recycled bisphenol

[0087] 1000g of high-heat-resistant polyarylate based on recycled bisphenol and 0.1g of light stabilizer 2,4,6-tris(2'-n-butoxyphenyl)-1,3,5-triazine were granulated by twin-screw extrusion to obtain resin granules. The dried granules were then extruded and cast in a casting machine to prepare a film with a thickness of 0.08mm. The casting machine temperature was 330℃, the feed rate was 0.2kg / min, and the screw speed was 60r / min. The film was then clamped in a biaxial stretching machine, preheated with hot air at 290℃ for 2min, and then stretched laterally by 4 times and then longitudinally by 5 times at a stretching rate of 120mm / min to prepare a film of uniform thickness. The transmittance at 450nm was measured to be 88.14% (see...). Figure 6 As shown in the figure, the tensile strength is 59.7 MPa.

[0088] Comparative Example 1

[0089] This comparative example is used to demonstrate the necessity of segmented temperature control process.

[0090] The steps (1), (3), (4), and (5) of the method for preparing a high heat-resistant and high light-transmitting polyarylate film based on recycled bisphenol in this comparative example are the same as those in Example 1, except that in step (2), the programmed segmented heating is changed to keep the polymerization temperature constant at 25°C.

[0091] The results showed that the obtained polyarylate resin had a viscosity of 0.42, a low molecular weight, and a glass transition temperature of 187°C (far lower than the glass transition temperature of the resin obtained in Example 1). Furthermore, the obtained resin had low strength and could not be successfully cast into a film or made into a strong sheet through step (5).

[0092] Comparative Example 2

[0093] 228.8 g of the recovered BPA monomer from step (1) of Example 1, 1 g of tetrabutylammonium bromide, and 80 g of lithium hydroxide were sequentially added to a reaction vessel containing 1000 g of water and stirred at 0 °C to dissolve. Then, 101.5 g of terephthaloyl chloride and 101.5 g of isophthaloyl chloride were dissolved in a dissolving vessel containing 1800 g of chloroform, and the acyl chloride solution in the dissolving vessel was added dropwise to the above reaction vessel.

[0094] This comparative example also uses segmented temperature control: first, the reaction is stirred at 5℃ for 5 hours; then the temperature of the reactor is raised to 16℃ and the reaction is continued to be stirred for 0.5 hours.

[0095] The remaining steps (purification, solidification and granulation, film preparation) are exactly the same as in Example 1.

[0096] The results showed that the resin obtained in Comparative Example 2 could be cast into a film, but the film surface had defects such as microcrystalline points and fisheyes (e.g. Figure 7As shown in the figure, the tensile strength is only 43 MPa.

[0097] Comparative Example 3

[0098] 312.8 g of the recovered cyclohexylbisphenol monomer, 0.1 g of 15-crown-5, and 82 g of sodium hydroxide from step (1) of Example 2 were sequentially added to a reaction vessel containing 2000 g of water and stirred at 5 °C to dissolve. Then, 60.9 g of terephthaloyl chloride and 142.1 g of isophthaloyl chloride were dissolved in a dissolving vessel containing 2200 g of dichloromethane, and the acyl chloride solution was added dropwise to the reaction vessel.

[0099] The reaction was carried out using a two-stage interfacial polymerization process: first, the reaction was stirred at 5°C for 4 hours; then the reaction temperature was raised to 15°C and the reaction was stirred for another 2.5 hours.

[0100] After the reaction was completed, subsequent processing was carried out according to the same purification, solidification granulation and film preparation process as in Example 2.

[0101] Experimental results:

[0102] The resulting polyarylate resin had an intrinsic viscosity of 0.47 dL / g (0.56 dL / g in Example 2), a significantly low molecular weight, and a glass transition temperature (Tg) of only 258.3℃ (e.g., ...). Figure 8 As shown, the temperature decreased by 11.3°C compared to 269.6°C in Example 2.

[0103] In the subsequent casting process, the resin melt has too fast a flow rate, low strength, and severe flow, making it impossible to prepare a cast film.

[0104] It should be noted that while the preferred embodiments of the present invention are given in the specification and accompanying drawings, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing polyarylates using recycled bisphenols, characterized in that, The process includes the following steps: in the presence of a catalyst and a base, in a mixed system of organic solvent and water, an interfacial polymerization reaction is carried out between a recovered bisphenol monomer containing impurities and an aromatic dicarboxylic acid chloride. The interfacial polymerization reaction is carried out using a segmented temperature control method: First, the first stage reaction is carried out at the first temperature to generate polyarylate prepolymer; Then, the reaction system is heated to a second temperature to carry out the second stage reaction, so that the impurities in the recovered bisphenol monomer participate in the end-capping reaction to obtain polyarylate; The first temperature is -15°C to 5°C, and the second temperature is 5°C to 30°C.

2. The method according to claim 1, characterized in that, The recovered bisphenol monomer is derived from the chemical degradation of waste polyester materials, and the impurities include the end-capping agents and / or antioxidants originally present in the waste polyester materials.

3. The method according to claim 2, characterized in that, The method for preparing the recovered bisphenol monomer includes the following steps: in the presence of a degradation catalyst and an alcohol solvent, waste polyester is subjected to a degradation reaction in an inert gas at 50-210°C. After the reaction is completed, the temperature is lowered to precipitate crude bisphenol. After solid-liquid separation, washing, and drying, recovered bisphenol monomer containing impurities is obtained. Furthermore, the purity of the recovered bisphenol monomer in step (1) is above 98%, and the recovered bisphenol monomer does not require a purification step to remove the impurities.

4. The method according to claim 1, characterized in that, The method further includes a purification step after the interfacial polymerization reaction is completed: the reaction mixture is allowed to stand and separate into layers, the aqueous phase is separated, the organic phase is washed with deionized water, and the washing is repeated 2 to 6 times to obtain a purified polyarylate resin solution. Furthermore, the method also includes a curing and granulation step: adding a diluent and an antioxidant to the purified polyarylate resin solution, mixing them evenly, and then feeding them into an atomizing granulation tower for curing and granulation, controlling the temperature of the atomizing granulation tower to be 20°C to 180°C, and the vacuum degree to be -0.05MPa to -0.095MPa.

5. The method according to any one of claims 1-4, characterized in that, The structural formula of the recovered bisphenol monomer is: ； Furthermore, the structural formula of the aromatic dicarboxylic acid chloride is: ； Further, the organic solvent is any one of 1,2-dichloroethane, 1,1-dichloroethane, 1,1,2,2-tetrachloroethane, chloromethane, dichloromethane, chloroform, carbon tetrachloride, cyclohexane, cyclohexanone, chlorobenzene, m-dichlorobenzene, 1,2,4-trichlorobenzene, or chloronaphthalene. Further, the catalyst is at least one selected from tetrabutylammonium bromide, tetrabutylammonium chloride, tetramethylammonium chloride, tetraethylammonium bromide, hexadecyltrimethylammonium chloride, dioctadecyldimethylammonium chloride, sodium gluconate, sodium dioctylsuccinate, sodium aziridine triacetate, sodium sorbate, sodium ethylenediaminetetraacetate, sodium ethylenediaminetetramethylidene phosphate, sodium glycocholate, sodium benzenesulfonate, sodium p-toluenesulfonate, sodium alginate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, dodecyl dimethyl betaine, PEG-200, PEG-400, PEG-600, PEG-800, 12-crown-4, 15-crown-5, benzo15-crown-5, 18-crown-6, 21-crown-7, Tween 80, and Span 60; Further, the alkali is any one of lithium hydroxide, sodium hydroxide, calcium hydroxide, potassium hydroxide, barium hydroxide, aluminum hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, barium carbonate, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, barium bicarbonate, ammonia, trimethylamine, triethylamine, tri-tert-butylamine, pyridine, or piperazine. Furthermore, the waste polyester is polycarbonate or polyarylate; Further, the degradation catalyst is TBD (1,5,7-triazabicyclo[4.4.0]dec-5-ene), TBD / HCl, TBD / HBr, TBD / HCOOH, TBD / CH3COOH, TBD / CH3CH2COOH, TBD / CH3OCH2COOH, MTBD (7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene), MTBD / HCl, MTBD / HBr, MTBD / HCOOH, MTBD / CH3COOH, MTBD / CH3CH2COOH, MTBD / CH3OCH2COOH, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), DBU / HCl, DBU / HBr, DBU / HCOOH, DBU / CH3COOH, DBU / CH3CH2COOH, DBU / CH3OCH2COOH, MDBU (1-methyl-1,8-diazaspiro[5.5]undecane), MDBU / HCl, MDBU / HBr, MDBU / HCOOH, MDBU / CH3COOH, MDBU / CH3CH2COOH, MDBU / CH3OCH2COOH, 1-butyl-3-methylimidazolium hydrochloride / anhydrous cobalt chloride ([BMIM]2[CoCl4]), zinc acetate, sodium acetate, magnesium acetate, zinc carbonate, potassium carbonate, potassium tert-butoxide, sodium ethoxide, tetrabutylammonium acetate, tetrabutylammonium hydroxide, potassium hydroxide, aluminum isopropoxide; Furthermore, the amount of the degradation catalyst used is 0.1-10% of the weight of the waste polyester material; Further, the alcohol solvent is any one of methanol, ethanol, propanol, tert-butanol, isopropanol, ethylene glycol, and propylene glycol; Furthermore, the amount of alcohol solvent used is 2-12 times the weight of the waste polyester material; Furthermore, the diluent is selected from chloroform or dichloromethane.

6. The method according to claim 1, characterized in that, The weight parts of the materials used in the method are as follows: 200-310 parts by weight of recovered bisphenol monomer, 203-455 parts by weight of aromatic dicarboxylic acid chloride, 0.02-10 parts by weight of catalyst, 80-200 parts by weight of alkali, 500-2500 parts by weight of water, and 300-4000 parts by weight of organic solvent. Further, the method includes: adding the recovered bisphenol monomer, catalyst and base to water, stirring and dissolving at -10 to 20°C to obtain an aqueous solution, dissolving aromatic dicarboxylic acid chloride in an organic solvent, and adding the obtained aromatic dicarboxylic acid chloride solution dropwise to the aqueous solution to carry out an interfacial polymerization reaction; Furthermore, the reaction time of the first stage reaction is 1 to 12 hours; the reaction time of the second stage reaction is 0.5 to 5 hours.

7. A polyarylate prepared by the method according to any one of claims 1 to 6.

8. A high heat-resistant and high light-transmitting polyarylate film, characterized in that, It is prepared by melt processing and stretching of the polyarylate according to claim 7.

9. The polyarylate film according to claim 8, characterized in that, The preparation method is as follows: the polyarylate is mixed with a light stabilizer and granulated by twin-screw extrusion to form granules; the granules are dried and then cast and extruded into films; the films are then preheated at 120°C to 280°C and then biaxially stretched to form thin films.

10. The polyarylate film according to claim 9, characterized in that, The casting extrusion temperature is 290-350℃, the feeding speed is 0.05-5kg / min, and the screw speed is 20-250r / min; Furthermore, the biaxial stretching includes first stretching laterally by 2 to 20 times at a stretching rate of 10 to 300 mm / min, and then stretching longitudinally by 2 to 20 times. Furthermore, the film has a transmittance of more than 85% at a wavelength of 450 nm, a tensile strength of more than 55 MPa, and a glass transition temperature of more than 190 °C for the polyarylate.

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