Preparation method and application of magnolol-based polyurethane and ultraviolet shielding film

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a magnolol-based polyurethane and a preparation method and application of an ultraviolet shielding film; the linear polyurethane is obtained by reacting bio-based diphenol and diisocyanate as raw materials under the catalysis of a catalyst, and the bulk polyurethane is obtained by further reacting dithiol as a crosslinking agent under light irradiation through a photoinitiator; the raw material is easy to obtain, the catalysts used are various in selectivity, the reaction yield is high, the prepared film has excellent optical performance, good mechanical performance and heat resistance, and ultraviolet shielding capacity; in addition, the application can expand the function and application field of lignin-based high polymer materials, and has the advantages of simple equipment, low cost, easy operation and the like.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically a method for preparing and applying magnolol-based polyurethane and ultraviolet shielding film. Background Technology

[0002] Polyurethane, short for polyurethane, is a polymer compound whose main chain contains repeating urethane segments. It consists of hard segments with glass transition temperatures above room temperature and soft segments with glass transition temperatures below room temperature. The microphase separation caused by the thermodynamic incompatibility of the hard and soft segments endows polyurethane with many excellent properties, and controlling this microphase separation to adjust its functionality has attracted considerable attention. Polyurethane combines the properties of plastics and rubber, making it a widely used high-performance material. After nearly ninety years of technological development, it has been widely applied in construction, transportation, home appliances, furniture, and daily necessities.

[0003] Transparent polyurethane not only possesses the excellent mechanical properties of traditional polyurethane but also exhibits good optical properties. Currently, many studies report the application of high-performance transparent polyurethane in advanced manufacturing industries, such as packaging materials for photovoltaic cells, aerospace materials, and bulletproof glass. Most commercially viable transparent polyurethanes are still synthesized from petroleum-based feedstocks. Growing environmental concerns and the petroleum energy crisis have driven the rapid development of sustainable biomass-based polymers. In recent years, there have been reports on the preparation of transparent polyurethanes using bio-based feedstocks, with the hydroxyl groups derived from chemically modified plant oils. However, these biomass-based polyurethanes cannot simultaneously possess both optical and mechanical properties.

[0004] Magnolol is a lignin-derived natural small molecule compound with antioxidant properties. It is a highly functional bioactive small molecule containing biphenyl, phenolic hydroxyl, and allyl groups, which endow it with high reactivity flexibility. However, research on its use in preparing biomass-based polyurethanes is very limited. CN116120514A discloses an isosorbide-based polyurethane and its preparation method. The bio-based transparent polyurethane prepared by this invention has advantages such as high strength and high visible light transmittance. CN112794985B discloses a transparent polyurethane optical material and its preparation method. The transparent polyurethane optical material prepared by this invention has high tensile strength and hardness, as well as a high refractive index.

[0005] However, these preparation methods have high requirements for conditions and the products do not have ultraviolet shielding capabilities.

[0006] Therefore, this invention proposes a method for preparing magnolol-based polyurethane and its application as an ultraviolet shielding film. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies and solve the technical problems existing in the background art, this invention proposes a method for preparing magnolol-based polyurethane and an ultraviolet shielding film and its application.

[0008] This invention is achieved through the following technical solution: a magnolol-based polyurethane, the structure of which is shown in Formula I or Formula II: Formula I; Formula 2; R1 is introduced by diisocyanate, and R2 is introduced by dithiol.

[0009] A method for preparing an ultraviolet shielding film suitable for the above-mentioned magnolol-based polyurethane includes the following steps: S1: Honokiol or honokiol and diisocyanate are used as raw materials, dissolved in a solvent, and reacted under the action of a catalyst and a protective atmosphere to obtain the reaction product; The diisocyanate may be one of the following: Specifically, these include: toluene diisocyanate, m-phenylene diisocyanate, terephthalene diisocyanate, 1,8-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 1,6-hexanediisocyanate, isophorone diisocyanate, m-phenylene dimethyl isocyanate, trans-1,4-cyclohexyl diisocyanate, trimethylhexanediisocyanate, 3,3'-dichloro-4,4'-diisocyanate biphenyl, 4,4'-bis(phenylisocyanate) oxide, 4-chloro-6-methylm-phenylene diisocyanate, and 4,4'-methylene di(2,6-diethylphenylisocyanate). 4,4'-Diisocyanate dicyclohexylmethane, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 4,4'-(perfluoropropane-2,2-diyl)bis(isocyanate), 2,5-toluene diisocyanate, 1,5-naphthalene diisocyanate, 1,12-diisocyanate tridecane, 4,4'-methylene bis(phenyl isocyanate), 4,4'-diisocyanate-3,3'-dimethylbiphenyl, trimethyl-1,3-phenylene diisocyanate, 4,4'-diisocyanate-3,3'-dimethyldiphenylmethane, 1,3-di(isocyanate-methyl)cyclohexane.

[0010] S2: The reaction product from S1 is separated and purified by washing with tert-butyl methyl ether and then dried to obtain linear polyurethane; the reaction formula is as follows: ; ; S3: The linear polyurethane and dithiol from S2 are dissolved in a solvent and added to a glass mold. Under the action of a photoinitiator, they react to obtain a bulk polyurethane. The reaction formula is as follows: ; ; The dithiol can be one of the following: Specifically, these are: 4,4'-thiodiphenylthiol, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, 1,11-undecanedithiol, 1,16-hexadecanedithiol, butane-1,2-dithiol, butane-2,3-dithiol, propane-1,2-dithiol, 1,2-phenylenediol, 1,4-phenylenediol, biphenyl-4,4'-dithiol, naphthalene-1,5-dithiol, 1,4-phenylenedimethylthiol, p-terphenyl-4,4'-dithiol, and 1,1'-binaphthyl-2,2'-dithiol. 3,7-Dithia-1,9-nonanedithiol, 1,3-benzenedimethylthiol, 5-bromo-1,3-phenyldithiol, 4-methylbenzene-1,2-dithiol, 3,6-dichloro-1,2-benzenediol, 3,6-dioxa-1,8-octanedithiol, 2,2'-oxobis(ethane-1-thiol), (4,5-dimethyl-1,2-phenylene)dimethylthiol, 2,2'-sulfonylbis(ethane-1-thiol), 6-(dibutylamino)-1,3,5-triazine-2,4-dithiol, 6-anilino-1,3,5-triazine-2,4-dithiol, hexa(ethylene glycol)dithiol, tetra(ethylene glycol)dithiol, dithiothreitol, dithioerythritol.

[0011] S4: Remove the bulk polyurethane from the glass mold in S3 and dry it in an oven to remove the solvent, thus obtaining the final target product, magnolol polyurethane film.

[0012] Preferably, the catalyst in S1 is one of dibutyltin dilaurate, dibutyltin oxide, dibutyltin dichlorodichloro, stannous octoate, dioctyltin dithiol, and potassium isooctanoate; and the photoinitiator in S3 is one of benzoin dimethyl ether and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0013] Preferably, the amount of catalyst used is 0.1%-0.2% of the molar amount of diisocyanate, and the amount of photoinitiator used is 1%-2% of the molar amount of dithiol.

[0014] Preferably, the molar ratio of magnolol or magnolol to diisocyanate in S1 is 2.05-2.2:1; the molar ratio of linear polyurethane to dithiol in S2 is 1:1.

[0015] Preferably, in S1, the protective atmosphere is one of nitrogen, helium, argon, or neon, the reaction time is 6-12 hours, and the reaction temperature is room temperature; in S3, the reaction is carried out in a glass mold in the dark before it begins, the reaction time is 0.5-1 hour, the reaction temperature is room temperature, and ultraviolet light is used to initiate the reaction.

[0016] Preferably, after the reaction in S1 is completed, the reaction is monitored by thin-layer chromatography to ensure that the raw materials have reacted completely. The mixture is then washed 3-5 times with tert-butyl methyl ether, filtered, the precipitate is collected, and dried to remove the solvent to obtain linear polyurethane.

[0017] Preferably, the solvent in S1 and S3 is one of dichloromethane, chloroform, N,N-dimethylformamide, tetrahydrofuran, and N-methylpyrrolidone.

[0018] An application of magnolol-based polyurethane in optical materials and high-strength materials.

[0019] The beneficial effects of this invention are: The raw materials used in this invention are readily available, the catalysts used are highly selective, and the reaction yield is high. The prepared films have excellent optical properties, good mechanical properties and heat resistance, as well as ultraviolet shielding ability. In addition, it can expand the functions and application fields of lignin-based polymer materials, and has the advantages of simple equipment, low cost and easy operation. Attached Figure Description

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments; Figure 1 This is a hydrogen nuclear magnetic resonance spectrum of the product obtained in this invention; Figure 2 This is another hydrogen nuclear magnetic resonance spectrum of the product obtained in this invention; Figure 3 The molecular weight and distribution of the products obtained in this invention are shown below. Figure 4 The infrared spectrum of the product obtained in this invention; Figure 5 The X-ray diffraction pattern of the product obtained in this invention; Figure 6 This is a product of the present invention. Detailed Implementation

[0021] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The invention will now be further described with reference to the accompanying drawings and specific embodiments. The preferred embodiments and materials described herein are for illustrative purposes only.

[0023] Example 1: like Figure 1 As shown in Figures 3, 4, 5, and 6: The method for preparing an ultraviolet shielding film includes the following steps: S1: Weigh 49.5g of magnolol and 31.26g of 1,6-hexamethylene diisocyanate (HDI), dissolve them in 50mL of dichloromethane, then add 1-2 drops of dibutyltin dilaurate, and react under the action of a catalyst and a protective atmosphere. Stir the reaction at room temperature for 12h to obtain a pale yellow solution. S2: The reaction product in S1 was separated and purified by washing it with tert-butyl methyl ether, filtering it, and drying the resulting precipitate in an oven at 60°C to obtain linear magnolol polyurethane (MH) with a yield of 96.7%. S3: Weigh 23.7g of linear magnolol polyurethane and 9.94g of 3,6-dioxa-1,8-octanedithiol (DODT), dissolve them in 20ml of dichloromethane, then add 0.56g of benzoin dimethyl ether, stir thoroughly at room temperature, pour into a glass mold, and react with ultraviolet light at a wavelength of 365nm for 0.5h. S4: Remove the bulk polyurethane from the glass mold in S3 and dry it in an oven at 60°C for 12 hours to obtain magnolol polyurethane film (MHD) with a yield of 98.3%.

[0024] In this example, tert-butyl methyl ether was used to wash the sample three times to remove reaction residues.

[0025] Example 2: like Figure 2 As shown in Figures 3, 4, 5, and 6: The method for preparing an ultraviolet shielding film includes the following steps: S1: Weigh 46.8g of magnolol and 43.97g of 4,4'-methylenebis(phenyl isocyanate) (MDI), dissolve them in 50mL of dichloromethane, then add 1-2 drops of dibutyltin dilaurate, and react under the action of a catalyst and a protective atmosphere. Stir the reaction at room temperature for 12h to obtain a pale yellow suspension. S2: The reaction product in S1 was separated and purified by washing it with tert-butyl methyl ether, filtering it, and drying the resulting precipitate in an oven at 60°C to obtain linear magnolol polyurethane (MH) with a yield of 95.9%. S3: Weigh 24.6g of linear magnolol polyurethane and 8.68g of 3,6-dioxa-1,8-octanedithiol (DODT), dissolve them in 20ml of N,N-dimethylformamide, then add 0.49g of benzoin dimethyl ether, stir thoroughly at room temperature, pour into a glass mold, and react with ultraviolet light at a wavelength of 365nm for 0.5h. S4: Remove the bulk polyurethane from the glass mold in S3 and dry it in an oven at 70°C for 48 hours to obtain magnolol polyurethane film (MHD) with a yield of 97.4%.

[0026] In this example, tert-butyl methyl ether was used to wash the sample three times to remove reaction residues.

[0027] Example 3: The method for preparing an ultraviolet shielding film includes the following steps: S1: Weigh 51.4g of magnolol and 32.46g of 1,6-hexanediisocyanate, dissolve them in 50mL of dichloromethane, then add 1-2 drops of dibutyltin dilaurate, and react under the action of a catalyst and a protective atmosphere. Stir the reaction at room temperature for 12h to obtain a pale yellow solution. S2: The reaction product in S1 was separated and purified. The reaction product was washed with tert-butyl methyl ether, filtered, and the resulting precipitate was dried in an oven at 60°C to obtain linear magnolol polyurethane (MH) with a yield of 94.4%. S3: Weigh 24.5g of linear magnolol polyurethane and 10.28g of 3,6-dioxa-1,8-octanedithiol (DODT), dissolve them in 20ml of dichloromethane, then add 0.58g of benzoin dimethyl ether, stir thoroughly at room temperature, pour into a glass mold, and react with ultraviolet light at a wavelength of 365nm for 0.5h. S4: Remove the bulk polyurethane from the glass mold in S3 and dry it in an oven at 60°C for 12 hours to obtain magnolol polyurethane film (MHD) with a yield of 95.7%.

[0028] In this example, tert-butyl methyl ether was used to wash the sample three times to remove reaction residues.

[0029] Example 4: The method for preparing an ultraviolet shielding film includes the following steps: S1: Weigh 47.6g of magnolol and 44.73g of 4,4'-methylenebis(phenyl isocyanate) (MDI), dissolve them in 50mL of dichloromethane, then add 1-2 drops of dibutyltin dilaurate, and react under the action of a catalyst and a protective atmosphere. Stir the reaction at room temperature for 12h to obtain a pale yellow suspension. S2: The reaction product in S1 was separated and purified by washing it with tert-butyl methyl ether, filtering it, and drying the resulting precipitate in an oven at 60°C to obtain linear magnolol polyurethane (MH) with a yield of 95.1%. S3: Weigh 25.4g of linear magnolol polyurethane and 8.96g of 3,6-dioxa-1,8-octanedithiol (DODT), dissolve them in 20ml of N,N-dimethylformamide, then add 0.5g of benzoin dimethyl ether, stir thoroughly at room temperature, pour into a glass mold, and react with ultraviolet light at a wavelength of 365nm for 0.5h. S4: Remove the bulk polyurethane from the glass mold in S3 and dry it in an oven at 70°C for 48 hours to obtain magnolol polyurethane film (MHD) with a yield of 96.8%.

[0030] In this example, tert-butyl methyl ether was used to wash the sample three times to remove reaction residues.

[0031] The UV shielding films obtained in Examples 1 to 4 were subjected to performance tests. Tensile strength was measured according to GB / T 2568-1995; optical transparency was tested using a Shimadzu UV-3600i Plus UV-Vis spectrophotometer; thermal stability was tested using a TA Discovery SDT650 under a nitrogen atmosphere; and the glass transition temperature was measured using a TA Discovery DMA850. The results are shown in Table 1. Table 1

[0032] This application presents a high-molecular-weight polyurethane film synthesized from biomass magnolol. It has high transparency, can block ultraviolet rays, and possesses excellent optical properties, good mechanical properties, and heat resistance.

[0033] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A magnolol-based polyurethane, characterized in that, Its structure is shown in Equation I or Equation II below: Formula I; Formula 2; R1 is introduced by diisocyanate, and R2 is introduced by dithiol.

2. A method for preparing an ultraviolet shielding film using the magnolol-based polyurethane of claim 1, characterized in that, Includes the following steps: S1: Honokiol or honokiol and diisocyanate are used as raw materials, dissolved in a solvent, and reacted under the action of a catalyst and a protective atmosphere to obtain the reaction product; S2: The reaction product in S1 is separated and purified by washing it with tert-butyl methyl ether and drying it to obtain linear polyurethane. S3: The linear polyurethane and dithiol in S2 are dissolved in a solvent and put into a glass mold, and reacted under the action of a photoinitiator to obtain bulk polyurethane; S4: Remove the bulk polyurethane from the glass mold in S3 and dry it in an oven to remove the solvent, thus obtaining the final target product, magnolol polyurethane film.

3. The method for preparing the ultraviolet shielding film according to claim 2, characterized in that, The catalyst in S1 is one of dibutyltin dilaurate, dibutyltin oxide, dibutyltin dichlorodibutyltin, stannous octoate, dioctyltin dithiol, and potassium isooctanoate; the photoinitiator in S3 is one of benzoin dimethyl ether and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-acetone.

4. The method for preparing the ultraviolet shielding film according to claim 3, characterized in that, The amount of catalyst used is 0.1%-0.2% of the molar amount of diisocyanate, and the amount of photoinitiator used is 1%-2% of the molar amount of dithiol.

5. The method for preparing the ultraviolet shielding film according to claim 2, characterized in that, The molar ratio of magnolol or magnolol to diisocyanate in S1 is 2.05-2.2:1; the molar ratio of linear polyurethane to dithiol in S2 is 1:

1.

6. The method for preparing the ultraviolet shielding film according to claim 2, characterized in that, In S1, the protective atmosphere is one of nitrogen, helium, argon, or neon, the reaction time is 6-12 hours, and the reaction temperature is room temperature. In S3, the reaction is carried out in a glass mold in the dark before it begins, the reaction time is 0.5-1 hour, the reaction temperature is room temperature, and ultraviolet light is used to initiate the reaction.

7. The method for preparing the ultraviolet shielding film according to claim 2, characterized in that, After the reaction in S1 is completed, monitor the reaction by thin-layer chromatography to ensure that the raw materials have reacted completely. Then wash with tert-butyl methyl ether 3-5 times, filter, collect the precipitate, dry it to remove the solvent, and obtain linear polyurethane.

8. The method for preparing the ultraviolet shielding film according to claim 2, characterized in that, The solvents in S1 and S3 are one of dichloromethane, chloroform, N,N-dimethylformamide, tetrahydrofuran, and N-methylpyrrolidone.

9. The application of the magnolol-based polyurethane as described in claim 1, characterized in that, It is applied to optical materials and high-strength materials.

Images