Enhanced polycarbonates, methods of making and use in automotive lighting systems

Abstract

The present application relates to the technical field of polycarbonate, and discloses a reinforced polycarbonate, a preparation method and application in an automobile lighting system.The reinforced polycarbonate comprises 75-90 parts by weight of polycarbonate and 10-25 parts by weight of modified lignin.The modified lignin is obtained by Mannich reaction of alkali lignin, 2-(methylamino)ethyl benzyl carbonate hydrochloride and formaldehyde, contains the same carbonate group as the polycarbonate, and introduces more benzene ring structures, significantly improves the compatibility between the lignin and the polycarbonate, enhances the mechanical properties of the polycarbonate, and has higher impact strength.The modified lignin still retains structures such as phenol, ketone and quinone type, can effectively absorb ultraviolet rays, and improves the light aging resistance of the polycarbonate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polycarbonate, in particular to a reinforced polycarbonate, a preparation method and application in automotive lighting system. BACKGROUND

[0002] Polycarbonate is an excellent engineering plastic with high transparency, good heat resistance and excellent electrical insulation, which is widely used in headlamp covers, instrument panels and other automotive interior and exterior trim parts. The traditional polycarbonate lampshade for vehicles is easily subjected to photoaging due to long-term exposure to sunlight and vehicle light, resulting in yellowing of the lampshade and a decrease in mechanical strength, so it is necessary to add light stabilizers and other additives.

[0003] Lignin is a natural compound widely present in plants, which is inexpensive and easy to obtain, has excellent thermal stability, contains a large number of aromatic rings, phenolic hydroxyl groups, ketones, quinone structures, and has high mechanical strength and can absorb ultraviolet rays. It can be used as a reinforcing agent, light stabilizer, etc., and has important applications in high polymer materials such as polycarbonate. Patent No. CN110903626B discloses a polycarbonate composite material and a preparation method thereof. Polycarbonate, acid lignin, maleic anhydride and dicumyl peroxide are reacted, extruded and melt-extruded to obtain a polycarbonate composite material with good impact resistance. However, the patent does not solve the problem of poor light aging resistance of polycarbonate. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a reinforced polycarbonate, a preparation method and application in automotive lighting system, which improves the compatibility between lignin and polycarbonate and solves the problem of poor light aging resistance of polycarbonate.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a reinforced polycarbonate and a preparation method thereof; 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:

[0006] (1) Add a solvent, alkali lignin, 2-(methylamino)ethyl benzyl carbonate hydrochloride and a cosolvent to a reaction container, drop in a sodium hydroxide solution, stir, drop in a formaldehyde aqueous solution, stir and react, drop in a sulfuric acid solution, precipitate, filter, wash the precipitate with water and ethanol, dry, and obtain modified lignin. The reaction formula is as follows:

[0007] .

[0008] (2) Mix the polycarbonate and the modified lignin in a mixer, then melt-extrude them in a twin-screw extruder, cut the particles, and obtain the reinforced polycarbonate.

[0009] 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).

[0010] Preferably, the amount of alkali lignin in (1) is 100 parts by weight, 2- (methylamino) ethyl benzyl carbonate hydrochloride is 16-44 parts by weight, and formaldehyde is 3.8-10.8 parts by weight.

[0011] Preferably, the mass fraction of the sodium hydroxide solution in (1) is 5-15%.

[0012] Preferably, the temperature of the reaction in (1) is 70-90℃, and the reaction time is 4-6h.

[0013] Preferably, the pH is adjusted to 3-4 by adding a sulfuric acid solution, and the mass fraction of the sulfuric acid solution is 30-70%.

[0014] Preferably, the temperature of the mixing in the mixer is 70-85℃, and the time is 20-40min; the temperature of the 1-6 zones of the twin-screw extruder is 200-260℃, and the screw rotation speed is 150-300r / min.

[0015] Preferably, the enhanced polycarbonate is applied in an automobile lighting system.

[0016] The 2- (methylamino) ethyl benzyl carbonate hydrochloride, formaldehyde, and alkali lignin in the application are subjected to a Mannich reaction to obtain modified lignin, which is then blended with polycarbonate to obtain enhanced polycarbonate.

[0017] The modified lignin in the application contains the same carbonate groups as polycarbonate, and more benzene ring structures are introduced, which improves the affinity between the lignin and the aromatic rings of polycarbonate, significantly improves the compatibility between the lignin and polycarbonate, enhances the mechanical properties of polycarbonate, and has higher impact strength.

[0018] The modified lignin in the application still retains structures containing phenol, ketone, and quinone, which can effectively absorb ultraviolet rays, improve the light aging resistance of polycarbonate, effectively reduce the light aging effect of light sources such as sunlight, automobile headlights, etc. on polycarbonate, and has good practical application in lighting systems such as automobile headlight covers. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the infrared spectrum of the modified lignin of Example 1. DETAILED DESCRIPTION

[0020] For a better understanding of the above technical solutions, the following describes the exemplary embodiments of the present application in more detail. Although the exemplary embodiments of the present application are shown, it should be understood that the present application 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 application and to fully convey the scope of the present application to those skilled in the art.

[0021] The following polycarbonate is an aromatic polycarbonate, model EGN2030CK 9005, from Dongguan Kaiyuan Plastic Raw Material Co., Ltd. Alkaline lignin is model SIGMA 471003, from Zhejiang Liansuo Biological Technology Co., Ltd.

[0022] To the reaction vessel, 20 mL of ethyl acetate, 1.75 g of N-BOC-N-methyl amino ethanol (CAS No. 57561-39-4), 0.97 mL of pyridine, 0.12 g of 4-dimethylamino pyridine were added, 1.57 mL of benzyl chloroformate (CAS No. 501-53-1) was added dropwise, and the reaction was stirred at 20°C for 2 h, then 0.65 mL of pyridine, 1.28 mL of benzyl chloroformate was added, and the reaction was continued for 5 days, then 0.81 mL of pyridine, 5 mL of ethyl acetate solution containing 1.43 mL of benzyl chloroformate was added in an ice water bath, and the reaction was stirred at 20°C for 2 h, finally diluted with ethyl acetate, extracted with water and saturated sodium chloride solution in turn, the ethyl acetate organic phase was dried with anhydrous magnesium sulfate to remove water, filtered, the filtrate was distilled under reduced pressure, the product was added to 10 mL of ethyl acetate solution with a concentration of 4 mol / L, stirred at 20°C for 2 h, diluted with 10 mL of ether, and the precipitate was washed with water after filtration, dried to obtain 2-(methylamino)ethyl benzyl carbonate hydrochloride, the structural formula is .

[0023] In an ice water bath, to the reaction vessel, 20 mL of ethyl acetate, 3.5 g of N-BOC-N-methyl amino ethanol, 1.35 g of isopropyl chloroformate (CAS No. 108-23-6), 1.94 mL of pyridine were added, and the reaction was stirred for 3.5 h, then 1.84 g of isopropyl chloroformate was added, and the reaction was stirred at 20°C for 2.5 h, diluted with ethyl acetate, extracted with water and saturated sodium chloride solution in turn, the ethyl acetate organic phase was dried with anhydrous magnesium sulfate to remove water, filtered, the filtrate was distilled under reduced pressure, the product was added to 10 mL of ethyl acetate solution with a concentration of 4 mol / L, stirred at 20°C for 2 h, washed with ethyl acetate after filtration, and the precipitate was dried to obtain 2-(methylamino)ethyl isopropyl carbonate hydrochloride, the structural formula is .

[0024] Example 1

[0025] (1) Into a reaction vessel, 3L of water, 300g of alkali lignin, 68g of 2-(methylamino)ethyl benzyl carbonate hydrochloride, 300mL of 1,4-dioxane, 260mL of 8% sodium hydroxide solution were added, and after stirring, 30mL of an aqueous solution containing 11.4g of formaldehyde (concentration: 380g / L) was added dropwise. The mixture was heated to 80°C, and stirred for 4h. A 40% sulfuric acid solution was added dropwise to adjust the pH to 3, and a precipitate was separated. The precipitate was filtered, washed with water and ethanol, and dried to obtain the modified lignin. Figure 1 In the infrared spectrum of the modified lignin, 3396cm -1 is the stretching vibration of phenolic hydroxyl group, 2898cm -1 is the absorption peak of methylene-CH2-, 1410-1533cm -1 is the characteristic absorption peak of benzene ring skeleton, 1115cm-1 is the stretching vibration peak of C-N bond, 1748cm -1 is the stretching vibration peak of -C=O- in carbonate.

[0026] (2) 9kg of polycarbonate and 1kg of the modified lignin were mixed in a mixer at 85°C for 30min, and then melt-extruded in a twin-screw extruder, with the temperature of 1-6 zones being 200°C, 235°C, 250°C, 260°C, 260°C, 260°C, and the screw rotation speed being 200r / min. The extrudate was pelletized to obtain the reinforced polycarbonate.

[0027] Example 2

[0028] (1) Into a reaction vessel, 3L of water, 300g of alkali lignin, 68g of 2-(methylamino)ethyl benzyl carbonate hydrochloride, 300mL of 1,4-dioxane, 260mL of 8% sodium hydroxide solution were added, and after stirring, 30mL of an aqueous solution containing 11.4g of formaldehyde (concentration: 380g / L) was added dropwise. The mixture was heated to 80°C, and stirred for 4h. A 40% sulfuric acid solution was added dropwise to adjust the pH to 3, and a precipitate was separated. The precipitate was filtered, washed with water and ethanol, and dried to obtain the modified lignin.

[0029] (2) 8.5kg of polycarbonate and 1.5kg of the modified lignin were mixed in a mixer at 80°C for 20min, and then melt-extruded in a twin-screw extruder, with the temperature of 1-6 zones being 200°C, 235°C, 250°C, 260°C, 260°C, 260°C, and the screw rotation speed being 150r / min. The extrudate was pelletized to obtain the reinforced polycarbonate.

[0030] Example 3

[0031] (1) Into a reaction vessel, 3 L of water, 300 g of alkali lignin, 132 g of 2- (methylamino) ethyl benzyl carbonate hydrochloride, 900 mL of 1,4-dioxane, 220 mL of 15% sodium hydroxide solution were added dropwise, and after stirring, 90 mL of an aqueous solution containing 32.4 g of formaldehyde (concentration: 360 g / L) was added dropwise, heated to 80°C, and stirred for 6 h. The pH was adjusted to 3 by adding a 50% sulfuric acid solution dropwise, and the precipitate was separated by filtration, washed with water and ethanol, and dried to obtain modified lignin.

[0032] (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 a temperature of 200°C, 235°C, 250°C, 260°C, 260°C, 260°C in the 1-6 zones and a screw rotation speed of 300 r / min. The pellets were obtained by cutting to obtain a reinforced polycarbonate.

[0033] Example 4

[0034] (1) Into a reaction vessel, 3 L of water, 300 g of alkali lignin, 132 g of 2- (methylamino) ethyl benzyl carbonate hydrochloride, 900 mL of 1,4-dioxane, 220 mL of 15% sodium hydroxide solution were added dropwise, and after stirring, 90 mL of an aqueous solution containing 32.4 g of formaldehyde (concentration: 360 g / L) was added dropwise, heated to 80°C, and stirred for 6 h. The pH was adjusted to 3 by adding a 50% sulfuric acid solution dropwise, and the precipitate was separated by filtration, washed with water and ethanol, and dried to obtain modified lignin.

[0035] (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 a temperature of 200°C, 235°C, 250°C, 260°C, 260°C, 260°C in the 1-6 zones and a screw rotation speed of 300 r / min. The pellets were obtained by cutting to obtain a reinforced polycarbonate.

[0036] Comparative Example 1

[0037] (1) 9 kg of polycarbonate was melt-extruded in a twin-screw extruder with a temperature of 200°C, 235°C, 250°C, 260°C, 260°C, 260°C in the 1-6 zones and a screw rotation speed of 200 r / min. The pellets were obtained by cutting to obtain polycarbonate pellets.

[0038] Comparative Example 2

[0039] (1) 9 kg polycarbonate, 1 kg alkali lignin were mixed in a mixer at 85°C for 30 min, and then melt-extruded in a twin-screw extruder, with the temperature of 1-6 zones being 200°C, 235°C, 250°C, 260°C, 260°C, 260°C, and the screw rotation speed being 200 r / min; pelletized to obtain the reinforced polycarbonate.

[0040] Comparative Example 3

[0041] (1) 3 L water, 300 g alkali lignin, 68 g 2-(methylamino)ethyl isopropyl carbonate hydrochloride, 300 mL 1,4-dioxane were added into a reaction vessel, 260 mL 8% sodium hydroxide solution was added dropwise, after stirring, 30 mL aqueous solution containing 11.4 g formaldehyde (380 g / L) was added dropwise, heated to 80°C, stirred for 4 h, 40% sulfuric acid solution was added dropwise to adjust the pH to 3, precipitate was separated, the precipitate was washed with water and ethanol, and dried to obtain the modified lignin.

[0042] (2) 9 kg polycarbonate, 1 kg modified lignin were mixed in a mixer at 85°C for 30 min, and then melt-extruded in a twin-screw extruder, with the temperature of 1-6 zones being 200°C, 235°C, 250°C, 260°C, 260°C, 260°C, and the screw rotation speed being 200 r / min; pelletized to obtain the reinforced polycarbonate.

[0043] Comparative Example 4

[0044] (1) 3 L pyridine, 300 g alkali lignin, 900 g acetic anhydride were added into a reaction vessel, heated to 60°C under nitrogen atmosphere, stirred for 12 h, water was added, after filtration, washed with ethanol and water, and dried to obtain the acetylated lignin.

[0045] (2) 9 kg polycarbonate, 1 kg acetylated lignin were mixed in a mixer at 85°C for 30 min, and then melt-extruded in a twin-screw extruder, with the temperature of 1-6 zones being 200°C, 235°C, 250°C, 260°C, 260°C, 260°C, and the screw rotation speed being 200 r / min; pelletized to obtain the reinforced polycarbonate.

[0046] The polycarbonate was injection molded into test bars by an injection molding machine. The impact strength was tested according to GB / T 1043.1-2008 standard, each sample was tested 3 times, and the average value was taken.

[0047] The polycarbonate samples were subjected to light aging test in a UV aging test chamber (wavelength 280-315 nm, power 180 W) for 30 days, and then were placed at room temperature for 2 h before testing the impact strength. Each group of samples was tested 3 times, and the average value was taken to calculate the impact strength retention rate W. W = A / A0 x 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.

[0048] Table 1: Performance of polycarbonate

[0049]

[0050] The polycarbonate of Comparative Example 1 has poor anti-UV aging performance, and the impact strength decreases greatly after light aging, with a low retention rate.

[0051] The modified lignin added in the polycarbonates of Examples 1-4 contains the same carbonate groups as polycarbonate, and the modified lignin introduces more benzene ring structures, improving the affinity between lignin and the aromatic ring of polycarbonate, significantly improving the compatibility between lignin and polycarbonate, enhancing the mechanical properties of polycarbonate, and having higher impact strength. Moreover, the modified lignin still retains structures containing phenol, ketone, quinone, etc., which can effectively absorb ultraviolet rays, improving the anti-light aging performance of polycarbonate, and having a very high impact strength retention rate after light aging.

[0052] The polycarbonate of Comparative Example 2 contains alkali lignin. Due to poor compatibility between the two, the dispersibility of alkali lignin in polycarbonate is poor, affecting the mechanical properties of polycarbonate and leading to a decrease in the initial impact strength, which is lower than that of Comparative Example 1. The alkali lignin contains structures containing phenol, ketone, quinone, etc., which can effectively absorb ultraviolet rays, improving the anti-light aging performance of polycarbonate, and the impact strength retention rate after light aging is higher than that of Comparative Example 1.

[0053] Comparative Example 3 uses 2-(methylamino)ethyl isopropyl carbonate hydrochloride, formaldehyde, and alkali lignin to perform a Mannich reaction to obtain modified lignin containing carbonate groups, which improves the compatibility between lignin and polycarbonate, is conducive to enhancing the mechanical properties and impact strength of polycarbonate, and the impact strength retention rate after light aging is also higher than that of Comparative Examples 1 and 2. However, 2-(methylamino)ethyl isopropyl carbonate hydrochloride and the preparation of modified lignin do not introduce more benzene ring structures, which is not conducive to improving the affinity between lignin and the benzene ring of polycarbonate, leading to a lower compatibility between the two than Example 1, and the initial impact strength of polycarbonate and the impact strength retention rate after light aging are lower than those of Example 1.

[0054] Comparative Example 4 uses acetic anhydride to react with the phenolic hydroxyl groups of alkali lignin to obtain acetylated lignin, which introduces ester groups into alkali lignin. The compatibility of the ester groups with polycarbonate is lower than that of carbonate groups, resulting in lower impact strength and impact strength retention rate after light aging of the material than Comparative Example 3. Moreover, acetylated lignin does not introduce more benzene ring structures, which is not conducive to improving the affinity between the benzene rings thereof and polycarbonate, resulting in lower compatibility between acetylated lignin and polycarbonate than Example 1, and the impact strength of the material is significantly lower than that of Example 1. At the same time, the phenolic hydroxyl groups of acetylated lignin are significantly reduced, which reduces the ultraviolet absorption performance of lignin, resulting in a significantly lower impact strength retention rate of polycarbonate after light aging than Example 1.

[0055] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any change or replacement within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An enhanced polycarbonate characterized by, 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 modified lignin comprises the following steps: adding a solvent, alkali lignin, 2-(methylamino)ethyl benzyl carbonate hydrochloride, a cosolvent into a reaction container, adding dropwise a sodium hydroxide solution, stirring, adding dropwise an aqueous formaldehyde solution after stirring, adding dropwise a sulfuric acid solution after stirring reaction, precipitating a precipitate, filtering, washing the precipitate with water and ethanol, drying, and obtaining the modified lignin.

2. The reinforced polycarbonate of claim 1, wherein, The solvent is water, and the cosolvent is 1,4-dioxane, and the volume ratio of the two is 1: (0.1-0.3).

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

4. The reinforced polycarbonate of claim 1, wherein, The mass fraction of the sodium hydroxide solution is 5-15%.

5. The reinforced polycarbonate of claim 1, wherein, The reaction temperature is 70-90℃, and the reaction time is 4-6h.

6. The reinforced polycarbonate of claim 1, wherein, 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 of 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 melt-extruding in a twin-screw extruder, pelletizing, and obtaining the reinforced polycarbonate.

8. The method of making reinforced polycarbonate according to claim 7, wherein, The mixing temperature in the mixer is 70-85℃, and the mixing time is 20-40min; the temperature of the first to sixth zones of the twin-screw extruder is 200-260℃, and the screw rotation speed is 150-300r / min.

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

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