Reinforced polycarbonate, preparation method and application of reinforced polycarbonate in automobile lighting system

Abstract

The invention relates to the technical field of polycarbonate, and discloses enhanced polycarbonate, a preparation method and application of the enhanced polycarbonate in an automobile lighting system.The enhanced polycarbonate is prepared from, by weight, 75-90 parts of polycarbonate and 10-25 parts of modified lignin; alkali lignin, 2-(methylamino) ethyl benzyl carbonate hydrochloride and formaldehyde are subjected to Mannich reaction to obtain modified lignin, the modified lignin contains carbonate groups the same as those of polycarbonate, and more benzene ring structures are introduced into the modified lignin, so that the compatibility between the lignin and the polycarbonate is remarkably improved, the mechanical property of the polycarbonate is enhanced, and the service life of the polycarbonate is prolonged. The impact strength is higher. The modified lignin still retains the structures of phenol, ketone, quinoneform and the like, and can effectively absorb ultraviolet rays, so that the light aging resistance of polycarbonate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polycarbonate, in particular to a reinforced polycarbonate, a preparation method and an application in an automobile lighting system. Background Art

[0002] Polycarbonate is a high-performance engineering plastic with high transparency, excellent heat resistance, and superior electrical insulation. It is widely used in automotive interior and exterior trims such as headlight covers and instrument panels. Traditional automotive polycarbonate lampshades are susceptible to photoaging due to long-term exposure to sunlight and headlights, causing yellowing and a decrease in mechanical strength. Therefore, additives such as light stabilizers are required.

[0003] Lignin is a natural compound widely found in plants. It is inexpensive, readily available, and has excellent thermal stability. It contains numerous aromatic rings, phenolic hydroxyl groups, ketones, and quinone structures, resulting in high mechanical strength and the ability to absorb ultraviolet light. It can be used as a reinforcing agent and light stabilizer, finding important applications in polymer materials such as polycarbonate. Patent Publication No. CN110903626B discloses a polycarbonate composite material and its preparation method. The polycarbonate, acid lignin, maleic anhydride, and dicumyl peroxide are subjected to reaction extrusion and melt extrusion to produce a polycarbonate composite material with excellent impact resistance. However, the patent does not address the poor light aging resistance of polycarbonate. Summary of the Invention

[0004] In response to the deficiencies of the prior art, the present invention provides an enhanced polycarbonate, a preparation method, and an application in automotive lighting systems, which improves the compatibility between lignin and polycarbonate and solves the problem of poor light aging resistance of polycarbonate.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a reinforced polycarbonate and a preparation method; the reinforced polycarbonate comprises 75-90 parts by weight of polycarbonate and 10-25 parts by weight of modified lignin; the preparation method of the reinforced polycarbonate comprises the following steps: (1) Add solvent, alkali lignin, 2-(methylamino)ethyl benzyl carbonate hydrochloride, and cosolvent to a reaction vessel, add sodium hydroxide solution dropwise, stir, and then add formaldehyde-containing aqueous solution dropwise. After stirring and reacting, add sulfuric acid solution dropwise to precipitate, filter, wash the precipitate with water and ethanol, and dry to obtain modified lignin. The reaction formula is: .

[0006] (2) Polycarbonate and modified lignin are mixed in a mixer, then melt-extruded in a twin-screw extruder and pelletized to obtain reinforced polycarbonate.

[0007] Preferably, the solvent in (1) is water and the cosolvent is 1,4-dioxane, and the volume ratio of the two is 1:(0.1-0.3).

[0008] Preferably, the amount of alkali lignin in (1) is 100 parts by weight, the amount of 2-(methylamino)ethyl benzyl carbonate hydrochloride is 16-44 parts by weight, and the amount of formaldehyde is 3.8-10.8 parts by weight.

[0009] Preferably, the mass fraction of the sodium hydroxide solution in (1) is 5-15%.

[0010] Preferably, the reaction temperature in (1) is 70-90°C, and the reaction time is 4-6 hours.

[0011] Preferably, sulfuric acid solution is added dropwise to adjust the pH to 3-4, and the mass fraction of the sulfuric acid solution is 30-70%.

[0012] Preferably, the mixing temperature in the mixer is 70-85° C., and the mixing time is 20-40 min; the temperature of zones 1-6 of the twin-screw extruder is 200-260° C., and the screw speed is 150-300 r / min.

[0013] Preferably, the reinforced polycarbonate is used in automotive lighting systems.

[0014] The beneficial technical effect of the present invention is as follows: 2-(methylamino)ethyl benzyl carbonate hydrochloride, formaldehyde and alkali lignin undergo a Mannich reaction to obtain modified lignin, which is then blended with polycarbonate to obtain enhanced polycarbonate.

[0015] The modified lignin of the present invention contains the same carbonate groups as polycarbonate and introduces more benzene ring structures, thereby improving the affinity between the aromatic rings of lignin and polycarbonate, significantly improving the compatibility between lignin and polycarbonate, enhancing the mechanical properties of polycarbonate, and having higher impact strength.

[0016] The modified lignin of the present invention still retains structures containing phenol, ketone, quinone and the like, can effectively absorb ultraviolet rays, improve the light aging resistance of polycarbonate, and effectively reduce the light aging effects of light sources such as sunlight and automobile headlights on polycarbonate, and has good practical applications in lighting systems such as automobile headlight shades. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the infrared spectrum of the modified lignin of Example 1. DETAILED DESCRIPTION

[0018] In order to better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0019] The polycarbonate described below is an aromatic polycarbonate, model EGN2030CK 9005, sourced from Dongguan Kaiyuan Plastic Materials Co., Ltd. The alkali lignin model SIGMA 471003 was sourced from Zhejiang Lianshuo Biotechnology Co., Ltd.

[0020] Add 20 mL of ethyl acetate, 1.75 g of N-BOC-N-methylaminoethanol (CAS No. 57561-39-4), 0.97 mL of pyridine, 0.12 g of 4-dimethylaminopyridine, 1.57mL benzyl chloroformate (CAS No. 501-53-1) was added dropwise, stirred at 20℃ for 2h, then 0.65mL pyridine and 1.28mL benzyl chloroformate were added, and the reaction was continued for 5 days. Then, 0.81mL pyridine and 5mL ethyl acetate solution containing 1.43mL benzyl chloroformate were added in an ice-water bath, and stirred at 20℃ for 2h. Finally, ethyl acetate was added for dilution, and the mixture was extracted with water and saturated sodium chloride solution in sequence. The ethyl acetate organic phase was dried over anhydrous magnesium sulfate to remove water, filtered, and the filtrate was distilled under reduced pressure. The product was added to 10mL 4mol / L ethyl acetate solution, stirred at 20℃ for 2h, diluted with 10mL ether, filtered, washed with water, and dried to obtain 2-(methylamino)ethyl carbonate benzyl ester hydrochloride, with the structural formula .

[0021] In an ice-water bath, 20 mL of ethyl acetate, 3.5 g of N-BOC-N-methylaminoethanol, 1.35 g of isopropyl chloroformate (CAS No. 108-23-6), and 1.94 mL of pyridine were added to the reaction vessel and stirred for 3.5 h. 1.84 g of isopropyl chloroformate was added and stirred for 2.5 h at 20 ° C. Ethyl acetate was added for dilution and the mixture was extracted with water and saturated sodium chloride solution in sequence. The ethyl acetate organic phase was dried over anhydrous magnesium sulfate to remove water, filtered, and the filtrate was distilled under reduced pressure. The product was added to 10 mL of 4 mol / L ethyl acetate solution and stirred for 2 h at 20 ° C. After filtering, the precipitate was washed with ethyl acetate and dried to obtain 2-(methylamino)ethyl carbonate isopropyl hydrochloride with the structural formula .

[0022] Example 1 (1) 3 L of water, 300 g of alkali lignin, 68 g of 2-(methylamino)ethyl benzyl carbonate hydrochloride, and 300 mL of 1,4-dioxane were added dropwise to a reaction vessel. 260 mL of 8% sodium hydroxide solution was added dropwise, and after stirring, 30 mL of an aqueous solution containing 11.4 g of formaldehyde (concentration of 380 g / L) was added dropwise. The mixture was heated to 80 °C and stirred for 4 h. 40% sulfuric acid solution was added dropwise to adjust the pH to 3. The precipitate was precipitated and filtered, washed with water and ethanol, and dried to obtain modified lignin. Figure 1 In the infrared spectrum, 3396 cm -1 is the stretching vibration of phenolic hydroxyl group, 2898cm -1 It is the absorption peak of methylene -CH2-, 1410-1533cm -1 It is the characteristic absorption peak of the benzene ring skeleton, 1115cm-1 is the stretching vibration peak of the CN bond, 1748cm -1 It is the stretching vibration peak of -C=O- in carbonate.

[0023] (2) 9 kg of polycarbonate and 1 kg of modified lignin were mixed in a mixer at 85°C for 30 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200°C, 235°C, 250°C, 260°C, 260°C, and 260°C, and the screw speed being 200 r / min; pelletized to obtain reinforced polycarbonate.

[0024] Example 2 (1) 3 L of water, 300 g of alkali lignin, 110 g of 2-(methylamino)ethyl benzyl carbonate hydrochloride, and 800 mL of 1,4-dioxane were added dropwise to a reaction vessel. 180 mL of a 15% sodium hydroxide solution was added dropwise, and after stirring, 64 mL of an aqueous solution containing 25 g of formaldehyde (concentration: 390.6 g / L) was added dropwise. The mixture was heated to 90 °C and stirred for 4 h. 30% sulfuric acid solution was added dropwise to adjust the pH to 3. The precipitate was precipitated and filtered, washed with water and ethanol, and dried to obtain modified lignin.

[0025] (2) 8.5 kg of polycarbonate and 1.5 kg of modified lignin were mixed in a mixer at 80 °C for 20 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200 °C, 235 °C, 250 °C, 260 °C, 260 °C, and 260 °C, and the screw speed being 150 r / min; pelletized to obtain reinforced polycarbonate.

[0026] Example 3 (1) 3 L of water, 300 g of alkali lignin, 132 g of 2-(methylamino)ethyl benzyl carbonate hydrochloride, and 900 mL of 1,4-dioxane were added to a reaction vessel. 220 mL of a 15% sodium hydroxide solution was added dropwise. After stirring, 90 mL of an aqueous solution containing 32.4 g of formaldehyde (concentration: 360 g / L) was added dropwise. The mixture was heated to 80 °C and stirred for 6 h. A 50% sulfuric acid solution was added dropwise to adjust the pH to 3. The precipitate was separated and filtered. The precipitate was washed with water and ethanol and dried to obtain modified lignin.

[0027] (2) 8 kg of polycarbonate and 2 kg of modified lignin were mixed in a mixer at 70 °C for 40 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200 °C, 235 °C, 250 °C, 260 °C, 260 °C, and 260 °C, and the screw speed being 300 r / min; pelletized to obtain reinforced polycarbonate.

[0028] Example 4 (1) 3 L of water, 300 g of alkali lignin, 90 g of 2-(methylamino)ethyl benzyl carbonate hydrochloride, and 600 mL of 1,4-dioxane were added to a reaction vessel. 320 mL of 5% sodium hydroxide solution was added dropwise. After stirring, 50 mL of an aqueous solution containing 18.2 g of formaldehyde (concentration: 364 g / L) was added dropwise. The mixture was heated to 70 °C and stirred for 6 h. 70% sulfuric acid solution was added dropwise to adjust the pH to 4. The precipitate was precipitated and filtered. The precipitate was washed with water and ethanol and dried to obtain modified lignin.

[0029] (2) 7.5 kg of polycarbonate and 2.5 kg of modified lignin were mixed in a mixer at 80 °C for 30 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200 °C, 235 °C, 250 °C, 260 °C, 260 °C, and 260 °C, and the screw speed being 200 r / min; pelletized to obtain reinforced polycarbonate.

[0030] Comparative Example 1 (1) 9 kg of polycarbonate was melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200°C, 235°C, 250°C, 260°C, 260°C, and 260°C, and the screw speed being 200 r / min; and pelletized to obtain polycarbonate pellets.

[0031] Comparative Example 2 (1) 9 kg of polycarbonate and 1 kg of alkali lignin were mixed in a mixer at 85 °C for 30 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200 °C, 235 °C, 250 °C, 260 °C, 260 °C, and 260 °C, and the screw speed being 200 r / min; pelletized to obtain reinforced polycarbonate.

[0032] Comparative Example 3 (1) 3 L of water, 300 g of alkali lignin, 68 g of 2-(methylamino)ethyl isopropyl carbonate hydrochloride, and 300 mL of 1,4-dioxane were added dropwise to a reaction vessel. 260 mL of 8% sodium hydroxide solution was added dropwise, and after stirring, 30 mL of an aqueous solution (380 g / L) containing 11.4 g of formaldehyde was added dropwise. The mixture was heated to 80 °C and stirred for 4 h. 40% sulfuric acid solution was added dropwise to adjust the pH to 3. The precipitate was precipitated and filtered, washed with water and ethanol, and dried to obtain modified lignin.

[0033] (2) 9 kg of polycarbonate and 1 kg of modified lignin were mixed in a mixer at 85°C for 30 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200°C, 235°C, 250°C, 260°C, 260°C, and 260°C, and the screw speed being 200 r / min; pelletized to obtain reinforced polycarbonate.

[0034] Comparative Example 4 (1) Add 3 L of pyridine, 300 g of alkali lignin, and 900 g of acetic anhydride to a reaction vessel, heat to 60 °C in a nitrogen atmosphere, stir and react for 12 h, add water, filter, wash with ethanol and water, and dry to obtain acetylated lignin.

[0035] (2) 9 kg of polycarbonate and 1 kg of acetylated lignin were mixed in a mixer at 85°C for 30 min, and then melt-extruded in a twin-screw extruder with the temperatures in zones 1-6 being 200°C, 235°C, 250°C, 260°C, 260°C, and 260°C, and the screw speed being 200 r / min; pelletized to obtain reinforced polycarbonate.

[0036] Polycarbonate was injection molded into test specimens using an injection molding machine. Impact strength was tested according to GB / T 1043.1-2008. Each specimen was tested three times and the average value was taken.

[0037] Polycarbonate specimens were subjected to a light aging test in a UV aging chamber (wavelength 280-315nm, power 180W) for 30 days. After aging at room temperature for 2 hours, the impact strength was retested. Each sample group was tested three times, and the average value was taken to calculate the impact strength retention rate (W). W = A / A0 × 100%. A0 is the initial impact strength, and A is the impact strength after light aging. The performance test results are shown in Table 1.

[0038] Table 1: Properties of polycarbonate

[0039] The polycarbonate of Comparative Example 1 has poor anti-ultraviolet aging performance, and its impact strength decreases significantly after light aging, with a low retention rate.

[0040] The modified lignin added to the polycarbonates of Examples 1-4 contains the same carbonate groups as the polycarbonate, and the modified lignin introduces more benzene ring structures, which increases the affinity between the lignin and the aromatic rings of the polycarbonate, significantly improving the compatibility between the lignin and the polycarbonate, enhancing the mechanical properties of the polycarbonate, and providing higher impact strength. Furthermore, the modified lignin still retains structures containing phenol, ketone, and quinone, which can effectively absorb ultraviolet light and improve the polycarbonate's resistance to light aging. The impact strength retention rate after light aging is very high.

[0041] Alkali lignin was added to the polycarbonate in Comparative Example 2. Due to the poor compatibility between the two, the dispersion of alkali lignin in polycarbonate was poor, which affected the mechanical properties of the polycarbonate and caused the initial impact strength to decrease, which was lower than that of Comparative Example 1. Alkali lignin contains structures such as phenol, ketone, and quinone, which can effectively absorb ultraviolet rays and improve the light aging resistance of polycarbonate. The impact strength retention rate after light aging is higher than that of Comparative Example 1.

[0042] Comparative Example 3 utilizes 2-(methylamino)ethyl isopropyl carbonate hydrochloride, formaldehyde, and alkali lignin to undergo a Mannich reaction. The resulting modified lignin contains carbonate groups, which improves the compatibility between lignin and polycarbonate, contributing to enhanced mechanical properties and impact strength of the polycarbonate. The impact strength retention after light aging is also higher than that of Comparative Examples 1 and 2. However, 2-(methylamino)ethyl isopropyl carbonate hydrochloride and the modified lignin used to prepare it do not introduce more benzene ring structures, which is not conducive to improving the affinity between lignin and the benzene rings of the polycarbonate. This results in lower compatibility between the two, and the initial impact strength and impact strength retention after light aging of the polycarbonate are lower than those of Example 1.

[0043] Comparative Example 4 utilizes acetic anhydride to react with the phenolic hydroxyl groups of alkali lignin to obtain acetylated lignin. This introduces ester groups into the alkali lignin, which have lower compatibility with polycarbonate than carbonate groups, resulting in lower impact strength and impact strength retention after light aging than those in Comparative Example 3. Furthermore, the acetylated lignin does not introduce more benzene ring structures, which is not conducive to improving its affinity with the benzene rings of polycarbonate. As a result, the compatibility between the acetylated lignin and polycarbonate is lower than that in Example 1, and the impact strength of the material is significantly lower than that in Example 1. Furthermore, the phenolic hydroxyl groups in the acetylated lignin are significantly reduced, which reduces the ultraviolet absorption properties of the lignin, resulting in a significantly lower impact strength retention after light aging of the polycarbonate than in Example 1.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention shall be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A reinforced polycarbonate, characterized in that: The enhanced polycarbonate comprises 75-90 parts by weight of polycarbonate and 10-25 parts by weight of modified lignin; The preparation method of the modified lignin comprises the following steps: adding a solvent, alkali lignin, 2-(methylamino)ethyl benzyl carbonate hydrochloride, and a cosolvent into a reaction container, dropwise adding a sodium hydroxide solution, stirring and then dropwise adding an aqueous solution containing formaldehyde, stirring and reacting, dropwise adding a sulfuric acid solution, precipitating a precipitate, filtering, washing the precipitate with water and ethanol, and drying to obtain the modified lignin.

2. The reinforced polycarbonate according to claim 1, characterized in that The solvent is water and the co-solvent is 1,4-dioxane, and the volume ratio of the two is 1:(0.1-0.3).

3. The reinforced polycarbonate according to claim 1, characterized in that The amount of the alkali lignin used is 100 parts by weight, the amount of 2-(methylamino)ethyl benzyl carbonate hydrochloride is 16-44 parts by weight, and the amount of formaldehyde is 3.8-10.8 parts by weight.

4. The reinforced polycarbonate according to claim 1, characterized in that The mass fraction of the sodium hydroxide solution is 5-15%.

5. The reinforced polycarbonate according to claim 1, characterized in that The reaction temperature is 70-90° C., and the reaction time is 4-6 hours.

6. The reinforced polycarbonate according to claim 1, characterized in that The sulfuric acid solution is added dropwise to adjust the pH to 3-4, and the mass fraction of the sulfuric acid solution is 30-70%.

7. A method for preparing the reinforced polycarbonate according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: mixing polycarbonate and modified lignin in a mixer, then melting and extruding the mixture in a twin-screw extruder, and pelletizing the mixture to obtain enhanced polycarbonate.

8. The method for preparing the enhanced polycarbonate according to claim 7, wherein: The mixing temperature in the mixer is 70-85° C., and the mixing time is 20-40 min. The temperature of zones 1-6 of the twin-screw extruder is 200-260° C., and the screw speed is 150-300 r / min.

9. Use of the reinforced polycarbonate obtained by the preparation method according to claim 8 in an automobile lighting system.

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