A high-weather-resistant modified polypropylene material and a preparation method thereof

Abstract

The application discloses a kind of high weather-resistant modified polypropylene material and preparation method thereof, belong to polypropylene material technical field.The raw materials include the following weight parts:71-83 polypropylene resin, 3-8 ethylene-octene copolymer, 6-12 nano titanium dioxide, 3-5 maleic anhydride grafted polypropylene, 2-6 weather-resistant additive, 0.3-0.5 lubricant and 0.05-0.09 initiator.Nano titanium dioxide can improve the weather resistance of the material;ethylene-octene copolymer can improve the impact toughness of polypropylene, without affecting other properties of the material;weather-resistant additive can jointly act from three aspects of ultraviolet resistance, oxidation resistance and heat resistance, greatly improve the weather resistance of the matrix, and has good stability;in summary, the polypropylene material prepared by the application has stable and efficient weather resistance, and has important application value in the field of battery box shell technology.

Description

Technical Field

[0001] This invention belongs to the field of polypropylene material technology, specifically, it relates to a modified polypropylene material with high weather resistance and its preparation method. Background Technology

[0002] With the booming development of the new energy vehicle industry, the requirements for material performance are becoming increasingly stringent. Polypropylene, as a common general-purpose plastic, demonstrates broad application prospects in this industry due to its outstanding mechanical properties, good processing performance, and relatively low cost. For example, in the manufacturing of battery boxes for new energy vehicles, polypropylene materials have been widely used due to their advantages. As a key component of the battery system in new energy vehicles, the performance of the battery box directly affects the safety and stability of the battery, and thus the performance and safety of the entire vehicle.

[0003] However, polypropylene materials have a significant problem: poor weather resistance. During long-term outdoor use, especially in critical components like battery box shells for new energy vehicles, ordinary polypropylene is prone to molecular chain breakage, surface powdering, and decreased mechanical properties due to prolonged exposure to complex environments such as sunlight, rain, and drastic temperature changes. This can be caused by ultraviolet radiation, thermo-oxidative aging, and other factors. Consequently, the battery box shell may become brittle, cracked, sticky, and yellowed / faded. These problems not only affect the appearance of the battery box but, more importantly, severely reduce its lifespan and protective performance, posing a potential threat to the safe operation of the battery.

[0004] Currently, to improve the weather resistance of polypropylene, the industry typically uses additives such as light stabilizers, antioxidants, and UV absorbers. These additives can delay the aging process of materials to some extent. However, traditional additives are prone to migration, lack durability, and the modification effect of a single additive is limited, making it difficult to cope with complex and changing environmental conditions. Therefore, there is an urgent need to invent a polypropylene material with high weather resistance modification to meet the higher requirements of the polypropylene material technology field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a modified polypropylene material with high weather resistance and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high weather-resistant modified polypropylene material comprises the following raw materials in parts by weight: 71-83 parts polypropylene resin, 3-8 parts ethylene-octene copolymer, 6-12 parts nano titanium dioxide, 3-5 parts maleic anhydride grafted polypropylene, 2-6 parts weather-resistant additives, 0.3-0.5 parts lubricant, and 0.05-0.09 parts initiator.

[0008] As a further technical solution, the lubricant is one of calcium stearate, stearic acid, and magnesium stearate.

[0009] As a further technical solution, the initiator is one of dicumyl peroxide and di-tert-butyl peroxide.

[0010] As a further technical solution, the weather-resistant additive is prepared through the following steps:

[0011] A1. Under dry nitrogen protection, pentaerythritol and anhydrous toluene were added to a three-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel and a reflux condenser. The apparatus was then placed in an ice-water bath at 0-5°C, and phosphorus trichloride was slowly added dropwise through the constant pressure dropping funnel. After the addition was completed, the ice bath was removed, the mixture was stirred evenly, and then heated to 75-80°C. The mixture was then refluxed at this temperature for 4-5 hours. After the reaction was completed, the initial product was obtained through post-processing.

[0012] A2. Under dry nitrogen protection, add the initial product and anhydrous toluene to a three-necked flask equipped with a mechanical stirrer and a constant pressure dropping funnel. Then place the apparatus in an ice-water bath at 0-5°C and slowly add 4-penten-1-ol dropwise through the constant pressure dropping funnel. After the addition is complete, remove the ice bath and heat to 80-85°C. Keep the reaction at this temperature for 6-8 hours under stirring. After the reaction is complete, perform post-processing to obtain the intermediate product.

[0013] A3. Under dry nitrogen protection, add the intermediate product, 4,4'-dihydroxybenzophenone, and anhydrous toluene to a three-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel, and a reflux condenser. Then, mix sodium hydroxide with distilled water and stir to dissolve the sodium hydroxide. Slowly add the solution dropwise to the flask through the dropping funnel. After the addition is complete, raise the temperature to 70-80℃ and maintain the temperature for 6-8 hours. After the reaction is complete, perform post-treatment to obtain the weather-resistant additive.

[0014] As a further technical solution, the ratio of pentaerythritol, anhydrous toluene, and phosphorus trichloride in step A1 is 13.6g:120mL:29.3-31.7g.

[0015] As a further technical solution, the ratio of the initial product, anhydrous toluene, and 4-penten-1-ol in step A2 is 26.3-28.7g:100mL:8.6g.

[0016] As a further technical solution, the ratio of the amount of intermediate product, 4,4'-dihydroxybenzophenone, anhydrous toluene, and sodium hydroxide in step A3 is 64.2-68.5g:21.4g:200mL:8.6-9.5g.

[0017] The principle of preparing weather-resistant additives according to this invention is as follows: First, in step A1, pentaerythritol and phosphorus trichloride react to generate a primary product; then, in step A2, the primary product reacts with 4-penten-1-ol to introduce an unsaturated carbon-carbon double bond, generating an intermediate product; finally, the intermediate product reacts with 4,4'-dihydroxybenzophenone under the catalysis of sodium hydroxide to obtain the weather-resistant additive. It is particularly important to note that the molar ratio of pentaerythritol to phosphorus trichloride in step A1 should be controlled at 1:2; and the molar ratio of the intermediate product to 4,4'-dihydroxybenzophenone in step A3 should be controlled at 2:1 to ensure complete reaction and reduce side reactions.

[0018] The reaction formula for preparing weather-resistant additives is as follows:

[0019]

[0020] From a performance perspective, the weather-resistant additive molecule prepared by this invention contains multiple functional groups. Among them, the ketone group can form a conjugated system with the adjacent benzene ring, which has certain UV resistance. The phosphite, as an antioxidant, can improve the antioxidant performance of the matrix to a certain extent. In addition, the two unsaturated double bonds introduced into the weather-resistant additive can crosslink with the matrix under the action of an initiator, improving the migration resistance and stability of the small molecule weather-resistant additive. Furthermore, because the weather-resistant additive contains two rigid benzene ring structures connected to polypropylene, which are both alkyl groups, it can improve the heat resistance of the matrix. Therefore, the prepared weather-resistant additive can act from three aspects: UV resistance, antioxidant, and heat resistance, significantly improving the weather resistance of the matrix.

[0021] This invention also provides a method for preparing a highly weather-resistant modified polypropylene material, comprising the following steps:

[0022] B1. Dry the polypropylene resin in an oven to remove moisture and prevent moisture from affecting the material properties during processing, thus obtaining dried polypropylene resin.

[0023] B2. Add the dried polypropylene resin, ethylene-octene copolymer, nano titanium dioxide, maleic anhydride grafted polypropylene, weather-resistant additives, lubricants and initiators to a high-speed mixer and mix them evenly to obtain a mixture.

[0024] B3. Add the mixture to a twin-screw extruder for melt blending and extrusion, then pelletize to obtain a modified polypropylene material with high weather resistance.

[0025] As a further technical solution, the drying temperature in step B1 is 80-90℃, and the time is 2-3 hours.

[0026] As a further technical solution, in step B2, the speed of the high-speed mixer is 800-1200 r / min, and the mixing time is 5-10 min.

[0027] As a further technical solution, the process parameters of the twin-screw extruder in step B3 are set as follows: zone 1 temperature 160-170℃, zone 2 temperature 170-180℃, zone 3 temperature 180-190℃, zone 4 temperature 180-190℃, die head temperature 170-180℃; screw speed 300-400r / min.

[0028] The beneficial effects of this invention are:

[0029] 1. The addition of nano-titanium dioxide to the raw materials of this invention has excellent photocatalytic activity and ultraviolet shielding effect. Furthermore, the addition of maleic anhydride-grafted polypropylene as a compatibilizer can improve the dispersibility of nano-titanium dioxide and better enhance the weather resistance of the material.

[0030] 2. The addition of ethylene-octene copolymer to the raw materials of this invention can improve the impact toughness of polypropylene, making the material less prone to brittleness and breakage during long-term use. At the same time, it has good compatibility with the polypropylene matrix and does not affect other properties of the material.

[0031] 3. The self-made weather-resistant additives added to the raw materials of this invention can work together from three aspects: UV resistance, oxidation resistance and heat resistance, which greatly improves the weather resistance of the matrix and has good stability;

[0032] In summary, the polypropylene material prepared by this invention has stable and efficient weather resistance, and has important application value in the field of battery box shell technology. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] Preparation of weather-resistant additives:

[0036] A1. Under dry nitrogen protection, add 13.6 g pentaerythritol and 120 mL anhydrous toluene to a three-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel and a reflux condenser. Then place the apparatus in an ice-water bath at 0 °C and slowly add 29.3 g phosphorus trichloride dropwise through the constant pressure dropping funnel. After the addition is complete, remove the ice bath, stir evenly, and then heat to 75 °C. Reflux the reaction at this temperature for 4 h. After the reaction is complete, cool to room temperature and remove toluene by vacuum distillation to obtain the initial product.

[0037] A2. Under dry nitrogen protection, 26.3 g of the initial product and 100 mL of anhydrous toluene were added to a three-necked flask equipped with a mechanical stirrer and a constant pressure dropping funnel. The apparatus was then placed in an ice-water bath at 0 °C, and 8.6 g of 4-penten-1-ol was slowly added dropwise through the constant pressure dropping funnel. After the addition was completed, the ice bath was removed, and the mixture was heated to 80 °C. The reaction was maintained at this temperature for 6 h under stirring. After the reaction was completed, the mixture was cooled to room temperature, washed with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain the intermediate product.

[0038] A3. Under dry nitrogen protection, 64.2 g of intermediate product, 21.4 g of 4,4'-dihydroxybenzophenone, and 200 mL of anhydrous toluene were added to a three-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel, and a reflux condenser. Then, 8.6 g of sodium hydroxide was mixed with 15 mL of distilled water and stirred until the sodium hydroxide dissolved. The solution was then slowly added dropwise to the flask through the dropping funnel. After the addition was complete, the temperature was raised to 70 °C and the reaction was maintained for 6 h. After the reaction was complete, hydrochloric acid was added to adjust the pH to neutral. The organic phase was separated and washed three times with deionized water. After drying with anhydrous sodium sulfate, the mixture was filtered and distilled under reduced pressure to remove toluene. The residue was purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 5:1) to obtain the weather-resistant additive.

[0039] A method for preparing a highly weather-resistant modified polypropylene material includes the following steps:

[0040] B1. Dry 71g of polypropylene resin in an 80℃ oven for 2 hours to remove moisture and prevent moisture from affecting the material properties during processing, thus obtaining dried polypropylene resin.

[0041] B2. Add the dried polypropylene resin, 3g of ethylene-octene copolymer, 6g of nano titanium dioxide, 3-5g of maleic anhydride grafted polypropylene, 2g of weather-resistant additive, 0.3g of calcium stearate and 0.05g of dicumyl peroxide to a high-speed mixer with a speed of 800r / min and mix for 5min to obtain the mixture.

[0042] B3. Add the mixture to a twin-screw extruder (zone 1 temperature 160℃, zone 2 temperature 170℃, zone 3 temperature 180℃, zone 4 temperature 180℃, die head temperature 170℃; screw speed 300r / min), perform melt blending extrusion, and pelletize to obtain a polypropylene material with high weather resistance.

[0043] Example 2

[0044] Preparation of weather-resistant additives:

[0045] A1. Under dry nitrogen protection, add 13.6 g pentaerythritol and 120 mL anhydrous toluene to a three-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel and a reflux condenser. Then place the apparatus in an ice-water bath at 5 °C and slowly add 31.7 g phosphorus trichloride dropwise through the constant pressure dropping funnel. After the addition is complete, remove the ice bath, stir evenly, and then heat to 80 °C. Reflux the reaction at this temperature for 5 h. After the reaction is complete, cool to room temperature and remove toluene by vacuum distillation to obtain the initial product.

[0046] A2. Under dry nitrogen protection, 28.7 g of the initial product and 100 mL of anhydrous toluene were added to a three-necked flask equipped with a mechanical stirrer and a constant pressure dropping funnel. The apparatus was then placed in an ice-water bath at 5 °C, and 8.6 g of 4-penten-1-ol was slowly added dropwise through the constant pressure dropping funnel. After the addition was completed, the ice bath was removed, and the mixture was heated to 85 °C. The reaction was maintained at this temperature for 8 h under stirring. After the reaction was completed, the mixture was cooled to room temperature, washed with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain the intermediate product.

[0047] A3. Under dry nitrogen protection, add 68.5g of intermediate product, 21.4g of 4,4'-dihydroxybenzophenone, and 200mL of anhydrous toluene to a three-necked flask equipped with a mechanical stirrer, a constant pressure dropping funnel, and a reflux condenser. Then, mix 9.5g of sodium hydroxide with 15mL of distilled water, stir to dissolve the sodium hydroxide, and slowly add it dropwise to the flask through the dropping funnel. After the addition is complete, raise the temperature to 80℃ and maintain the reaction for 8 hours. After the reaction is complete, add hydrochloric acid to adjust the pH to neutral. After separation, take the organic phase, wash it three times with deionized water, add anhydrous sodium sulfate to dry, filter, and remove toluene by vacuum distillation. The residue is purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 5:1) to obtain the weather-resistant additive.

[0048] A method for preparing a highly weather-resistant modified polypropylene material includes the following steps:

[0049] B1. Dry 77g of polypropylene resin in an oven at 85℃ for 3 hours to remove moisture and prevent moisture from affecting the material properties during processing, thus obtaining dried polypropylene resin.

[0050] B2. Add the dried polypropylene resin, 5g of ethylene-octene copolymer, 9g of nano titanium dioxide, 4g of maleic anhydride-grafted polypropylene, 4g of weather-resistant additive, 0.4g of stearic acid and 0.07g of di-tert-butyl peroxide to a high-speed mixer with a rotation speed of 1000r / min and mix for 10min to obtain the mixture.

[0051] B3. Add the mixture to a twin-screw extruder (zone 1 temperature 170℃, zone 2 temperature 180℃, zone 3 temperature 190℃, zone 4 temperature 190℃, die head temperature 180℃; screw speed 400r / min), perform melt blending extrusion, and pelletize to obtain a high weather-resistant modified polypropylene material.

[0052] Example 3

[0053] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, a method for preparing a highly weather-resistant modified polypropylene material includes the following steps:

[0054] B1. Dry 83g of polypropylene resin in a 90℃ oven for 3 hours to remove moisture and prevent moisture from affecting the material properties during processing, thus obtaining dried polypropylene resin.

[0055] B2. Add the dried polypropylene resin, 8g of ethylene-octene copolymer, 12g of nano titanium dioxide, 5g of maleic anhydride-grafted polypropylene, 6g of weather-resistant additive, 0.5g of magnesium stearate and 0.09g of di-tert-butyl peroxide to a high-speed mixer with a rotation speed of 1200r / min and mix for 10min to obtain the mixture.

[0056] B3. Add the mixture to a twin-screw extruder (zone 1 temperature 170℃, zone 2 temperature 180℃, zone 3 temperature 190℃, zone 4 temperature 190℃, die head temperature 180℃; screw speed 400r / min), perform melt blending extrusion, and pelletize to obtain a high weather-resistant modified polypropylene material.

[0057] Comparative Example 1

[0058] The only difference between this comparative example and Example 2 is that in this comparative example, 4g of antioxidant 168 was used to replace the weather-resistant additive to obtain polypropylene material.

[0059] Comparative Example 2

[0060] The only difference between this comparative example and Example 2 is that in this comparative example, 4g of UV531 was used to replace the weather-resistant additive to obtain polypropylene material.

[0061] Performance tests were conducted on Examples 1, 2, and 3, and Comparative Examples 1 and 2, according to the following criteria:

[0062] The heat distortion temperature under a load of 1.82 MPa was determined according to GB / T 1634.2-2019 standard.

[0063] The oxidation induction period was determined according to GB / T 19466.6-2009 standard;

[0064] The test samples were prepared, and the surface condition of the material was determined by using a UVB-313 lamp for 500 hours of aging according to GB / T 16422.3-2014 standard; the retention rate of the additives was analyzed by HPLC.

[0065] The measurement results are shown in the table below:

[0066]

[0067] As can be seen from the table above, the polypropylene material prepared in the embodiments of the present invention has improved heat resistance, oxidation resistance and UV resistance due to the addition of weather-resistant additives, which are superior to the single functional additives added in the comparative proportion. In addition, it has good stability. Therefore, the present invention has important application value in the field of battery box shell technology.

[0068] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A high weathering modified polypropylene material, characterized in that, The raw materials include the following parts by weight: 71-83 parts polypropylene resin, 3-8 parts ethylene-octene copolymer, 6-12 parts nano titanium dioxide, 3-5 parts maleic anhydride grafted polypropylene, 2-6 parts weather-resistant additives, 0.3-0.5 parts lubricant and 0.05-0.09 parts initiator; The weather-resistant additive is prepared through the following steps: A1. Add pentaerythritol and anhydrous toluene to a flask. Add phosphorus trichloride dropwise in an ice-water bath at 0-5°C. After the addition is complete, remove the ice bath, stir, and reflux at 75-80°C for 4-5 hours. The reaction is complete, and the initial product is obtained. A2. Add the initial product and anhydrous toluene to a flask. In an ice-water bath at 0-5°C, add 4-penten-1-ol dropwise. After the addition is complete, remove the ice bath and stir the reaction at 80-85°C for 6-8 hours. Once the reaction is complete, the intermediate product is obtained. A3. Add the intermediate product, 4,4'-dihydroxybenzophenone and anhydrous toluene to a flask, then mix sodium hydroxide with distilled water and add it dropwise to the flask. After the addition is complete, react at 70-80℃ for 6-8 hours. Once the reaction is complete, the weather-resistant additive is obtained.

2. The weatherable modified polypropylene material of claim 1, wherein, The lubricant is one of calcium stearate, stearic acid, and magnesium stearate.

3. The weatherable modified polypropylene material of claim 1, wherein, The initiator is one of dicumyl peroxide and di-tert-butyl peroxide.

4. The high weather-resistant modified polypropylene material according to claim 1, characterized in that, In step A1, the ratio of pentaerythritol, anhydrous toluene, and phosphorus trichloride is 13.6 g: 120 mL: 29.3-31.7 g.

5. The weatherable modified polypropylene material of claim 1, wherein, In step A2, the ratio of the initial product, anhydrous toluene, and 4-penten-1-ol is 26.3-28.7 g: 100 mL: 8.6 g.

6. The weatherable modified polypropylene material of claim 1, wherein, In step A3, the ratio of the intermediate product, 4,4'-dihydroxybenzophenone, anhydrous toluene, and sodium hydroxide is 64.2-68.5 g: 21.4 g: 200 mL: 8.6-9.5 g.

7. The method of producing a weather-resistant modified polypropylene material according to any one of claims 1 to 6, characterized in that, Includes the following steps: Polypropylene resin is dried in an oven to obtain dried polypropylene resin, which is then added to a high-speed mixer along with ethylene-octene copolymer, nano titanium dioxide, maleic anhydride-grafted polypropylene, weather-resistant additives, lubricants, and initiators. After being mixed evenly, a mixture is obtained. This mixture is then added to a twin-screw extruder for melt blending and extrusion, followed by pelleting to obtain a polypropylene material with high weather resistance.

8. The method for preparing a highly weather-resistant modified polypropylene material according to claim 7, characterized in that, The drying temperature is 80-90℃, and the time is 2-3 hours.

9. The method for preparing a highly weather-resistant modified polypropylene material according to claim 7, characterized in that, The high-speed mixer operates at a speed of 800-1200 r / min and a mixing time of 5-10 min.

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