A kind of recycled polypropylene modified plastic and preparation method thereof

Abstract

The invention relates to a recycled polypropylene modified plastic and a preparation method thereof, belonging to the technical field of modified materials. The plastic comprises 100 parts of recycled polypropylene, 15-20 parts of a toughening modifier, 1-1.5 parts of an initiator, 3-5 parts of a compatibilizer, 1-2 parts of an antioxidant, 1-2 parts of a light stabilizer and 2-3 parts of a lubricant in parts by weight; wherein the toughening modifier has good compatibility with a recycled polypropylene resin matrix, forms a soft connection between silicon dioxide and the recycled polypropylene resin, and is beneficial to improving the toughening effect of silicon dioxide; secondly, the toughening modifier can be grafted onto a recycled polypropylene molecular chain under the action of the initiator, thereby increasing the degree of branching; finally, hydrogen bonds exist between amide structures on the branch chains; when an external force acts on the recycled polypropylene resin matrix, the hydrogen bonds are preferentially dissociated, thereby weakening the influence of the external force on the main chain, effectively alleviating the stress concentration phenomenon; meanwhile, the hydrogen bonds can be formed again at room temperature, thereby realizing self-healing ability.

Description

Technical Field

[0001] The invention belongs to the technical field of modified materials, and in particular relates to a recycled polypropylene modified plastic and a preparation method thereof. Background Art

[0002] With the vigorous development of science and technology, the application of plastics is very extensive in our lives. With its excellent performance, it has gradually replaced some traditional metal materials in many fields. Polypropylene (PP) is widely used in agricultural films, household daily necessities, industrial products and other fields because of its high heat deformation temperature, excellent rigidity, electrical insulation and low density. Due to its good comprehensive performance, PP is currently one of the most widely used and fastest growing resins in the world. The large-scale use of PP will generate a large amount of waste. The recycling of PP is beneficial to environmental protection, saving resources and meeting the strategic requirements of sustainable development.

[0003] However, during the use of PP, under the influence of factors such as light, heat, oxygen and external force, the polymer chain breaks and free radicals are generated. The free radicals react with oxygen atoms in the air to produce peroxidation reaction. The peroxides produced in this process can decompose to produce new free radicals. This reaction process continues until a relatively stable product is produced. The whole process is stopped, which leads to changes in the molecular structure, resulting in the brittleness of the recycled PP material becoming stronger and the impact resistance decreasing, further limiting its application and development in the field of modified material technology. Summary of the invention

[0004] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a recycled polypropylene modified plastic and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A recycled polypropylene modified plastic comprises the following raw materials in parts by weight:

[0007] 100 parts of recycled polypropylene, 15-20 parts of toughening modifier, 1-1.5 parts of initiator, 3-5 parts of compatibilizer, 1-2 parts of antioxidant, 1-2 parts of light stabilizer and 2-3 parts of lubricant;

[0008] Preparation of toughening modifier:

[0009] Step A1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reaction kettle, the stirring reaction rate was controlled to be 300-400 r / min, the temperature was raised to 25-30° C., the reaction was stirred for 3-5 hours, and then the amide intermediate was obtained by vacuum rotary evaporation;

[0010] Further, the usage ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF is 1 mol: 1 mol: 15-18 g: 7 g: 400 mL;

[0011] In the above reaction, dimethylolpropionic acid and 3-aminopropyltriethoxysilane undergo an amidation reaction to graft the silane coupling agent onto the dimethylolpropionic acid molecule. The specific reaction process is as follows:

[0012]

[0013] Step A2: taking an amide intermediate, propylene chloride, sodium hydroxide and ethylene dichloride, mixing and feeding them into a reaction kettle, controlling the stirring reaction rate to be 200-300 r / min, heating to 40-50° C., stirring and reacting for 3-4 hours, and then vacuum rotary evaporation to obtain an unsaturated amide intermediate;

[0014] Further, the usage ratio of the amide intermediate, propylene chloride, sodium hydroxide and ethylene dichloride is 1 mol: 2 mol: 5-8 g: 500 mL;

[0015] In the above reaction, the amide intermediate reacts with allyl chloride to graft the unsaturated double bond onto the amide intermediate. The specific reaction process is as follows:

[0016]

[0017] Step A3: taking the unsaturated amide intermediate, silicon dioxide and isopropanol solution, mixing and feeding them into a reactor, controlling the stirring reaction rate to be 500-800 r / min, heating to 60-65° C., stirring and reacting for 6 hours, then transferring to a drying oven, controlling the drying oven temperature to be 90° C., and drying for 2 hours to obtain a toughening modifier;

[0018] Furthermore, the dosage ratio of the unsaturated amide intermediate, silicon dioxide and isopropanol is 15-20 g: 5 g: 100 mL; the mass fraction of the isopropanol solution is 70%;

[0019] The silane coupling agent structure in the unsaturated amide intermediate is coupled with silicon dioxide, and the unsaturated amide intermediate is grafted onto the surface of silicon dioxide to form an inorganic-organic synergistic toughening composite.

[0020] A method for preparing recycled polypropylene modified plastic:

[0021] Step S1: mixing recycled polypropylene, toughening modifier, initiator, compatibilizer, antioxidant, light stabilizer and lubricant into a mixer, controlling the mixing temperature to be 160° C., and mixing for 1 hour to obtain a batch;

[0022] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 200-210°C, 210-220°C, 220-240°C, 240-250°C, 240-250°C, 220-230°C, applying 60-70r / min, and an extrusion mass flow rate of 30-40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0023] Beneficial effects of the present invention:

[0024] The invention discloses a recycled polypropylene modified plastic. The recycled polypropylene resin is used as a matrix material. A toughening modifier is compounded and mixed. Compared with the existing recycled polypropylene resin, the plastic has higher impact toughness and can still maintain good impact toughness after multiple fatigue damage tests. Firstly, the toughening modifier has good compatibility with the recycled polypropylene resin matrix, forms a soft connection between silicon dioxide and the recycled polypropylene resin, and uniformly disperses silicon dioxide in the recycled polypropylene resin matrix, which is beneficial to improving the toughening effect of silicon dioxide. Secondly, the unsaturated double bond structure in the toughening modifier can react with the macromolecular free radicals in the recycled polypropylene resin matrix under the action of an initiator, so that the toughening modifier is grafted onto the recycled polypropylene molecular chain to form a graft copolymer. The recycled polypropylene resin Although the increase in the degree of branching of the lipid matrix will slightly reduce its mechanical strength, its impact resistance is improved; finally, there are dynamically reversible hydrogen bonds between the amide structures in the toughening modifier. When external force acts on the recycled polypropylene resin matrix, the recycled polypropylene molecular chain with a higher degree of branching can quickly transfer and disperse the impact energy to the branch chain through chain segment movement. The relatively weak hydrogen bonds on the branch chain will dissociate preferentially and can dissipate the energy, thereby weakening the influence of external force on its main chain, effectively alleviating the stress concentration phenomenon caused by external force, and further improving its impact resistance. When the external force disappears, the hydrogen bonds can be formed again at room temperature, which helps to restore the impact resistance of the recycled polypropylene matrix, realize self-healing ability, and further enhance the impact resistance of recycled polypropylene plastics. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] The specific implementation process of preparing a wear-resistant modified plastic in this embodiment is as follows:

[0028] 1) Preparation of toughening modifier

[0029] a1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reactor, the stirring reaction rate was controlled to be 300 r / min, the temperature was raised to 25°C, and the stirring reaction was carried out for 3 hours, and then the amide intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF was 1 mol: 1 mol: 15 g: 7 g: 400 mL;

[0030] a2: Take the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride, mix them and feed them into a reactor, control the stirring reaction rate to 200r / min, heat to 40°C, stir and react for 3h, and then evaporate under reduced pressure to obtain the unsaturated amide intermediate; in the above reaction, the amount ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1mol:2mol:5g:500mL;

[0031] a3: Take the unsaturated amide intermediate, silicon dioxide and isopropanol solution with a mass fraction of 70% and mix them into a reactor, control the stirring reaction rate to 500r / min, heat to 60°C, stir and react for 6 hours, then transfer to a drying oven, control the temperature of the drying oven to 90°C, and dry for 2 hours to obtain a toughening modifier; in the above reaction, the dosage ratio of the unsaturated amide intermediate, silicon dioxide and isopropanol is 15g:5g:100mL;

[0032] 2) Preparation of recycled polypropylene modified plastics

[0033] s1: 100 parts of recycled polypropylene [both the present embodiment and the comparative example use MFR (230°C, 2.16kg=10-40g / 10min)], 15 parts of toughening modifier, 1 part of initiator (both the present embodiment and the comparative example use AI BN initiator), 3 parts of compatibilizer (both the present embodiment and the comparative example use toughening compatibilizer of Shanghai Qihe Chemical Co., Ltd., model QHE206), 1 part of antioxidant (both the present embodiment and the comparative example use antioxidant 1010), 1 part of light stabilizer (both the present embodiment and the comparative example use zinc oxide) and 2 parts of lubricant (both the present embodiment and the comparative example use zinc stearate) are mixed and added into a mixer, the mixing temperature is controlled to be 160°C, and the batch is obtained after mixing for 1 hour;

[0034] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 200°C, 210°C, 220°C, 240°C, 240°C, 220°C, applying 60r / min, and the extrusion mass flow rate is 30kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0035] Example 2

[0036] The specific implementation process of preparing a wear-resistant modified plastic in this embodiment is as follows:

[0037] 1) Preparation of toughening modifier

[0038] a1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reactor, the stirring reaction rate was controlled to be 320 r / min, the temperature was raised to 26°C, and the stirring reaction was performed for 4 hours, and then the amide intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF was 1 mol: 1 mol: 16 g: 7 g: 400 mL;

[0039] a2: Mix the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride and add them to a reactor, control the stirring reaction rate to 220r / min, heat to 42°C, stir and react for 4h, and then evaporate under reduced pressure to obtain an unsaturated amide intermediate; in the above reaction, the amount ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1mol:2mol:6g:500mL;

[0040] a3: Take the unsaturated amide intermediate, silicon dioxide and 70% isopropanol solution and mix them into a reactor, control the stirring reaction rate to 600r / min, heat to 61°C, stir and react for 6h, then transfer to a drying oven, control the temperature of the drying oven to 90°C, and dry for 2h to obtain a toughening modifier; in the above reaction, the dosage ratio of the unsaturated amide intermediate, silicon dioxide and isopropanol is 16g:5g:100mL;

[0041] 2) Preparation of recycled polypropylene modified plastics

[0042] s1: 100 parts of recycled polypropylene, 16 parts of toughening modifier, 1.1 parts of initiator, 4 parts of compatibilizer, 2 parts of antioxidant, 2 parts of light stabilizer and 3 parts of lubricant were mixed and added into a mixer, the mixing temperature was controlled to be 160°C, and the compound was obtained after mixing for 1 hour;

[0043] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 205°C, 215°C, 225°C, 245°C, 245°C, 225°C, applying 70r / min, and the extrusion mass flow rate is 40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0044] Example 3

[0045] The specific implementation process of preparing a wear-resistant modified plastic in this embodiment is as follows:

[0046] 1) Preparation of toughening modifier

[0047] a1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reactor, the stirring reaction rate was controlled to be 340r / min, the temperature was raised to 27°C, and the stirring reaction was performed for 4 hours, and then the amide intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF was 1 mol: 1 mol: 17g: 7g: 400mL;

[0048] a2: Mix the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride and add them to a reactor, control the stirring reaction rate to 240r / min, heat to 44°C, stir and react for 4 hours, and then evaporate under reduced pressure to obtain an unsaturated amide intermediate; in the above reaction, the amount ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1 mol: 2 mol: 7 g: 500 mL;

[0049] a3: unsaturated amide intermediate, silica and 70% isopropanol solution were mixed and added into a reactor, the stirring reaction rate was controlled to be 700r / min, the temperature was raised to 62°C, and the mixture was stirred for 6 hours before being transferred to a drying oven, the temperature of the drying oven was controlled to be 90°C, and the toughening modifier was obtained after being dried for 2 hours; in the above reaction, the dosage ratio of unsaturated amide intermediate, silica and isopropanol was 17g:5g:100mL;

[0050] 2) Preparation of recycled polypropylene modified plastics

[0051] s1: 100 parts of recycled polypropylene, 17 parts of toughening modifier, 1.2 parts of initiator, 5 parts of compatibilizer, 2 parts of antioxidant, 2 parts of light stabilizer and 3 parts of lubricant were mixed and added into a mixer, the mixing temperature was controlled to be 160°C, and the compound was obtained after mixing for 1 hour;

[0052] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 210°C, 220°C, 230°C, 250°C, 250°C, 230°C, applying 70r / min, and the extrusion mass flow rate is 40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0053] Example 4

[0054] The specific implementation process of preparing a wear-resistant modified plastic in this embodiment is as follows:

[0055] 1) Preparation of toughening modifier

[0056] a1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reactor, the stirring reaction rate was controlled to be 360r / min, the temperature was raised to 28°C, and the stirring reaction was performed for 4 hours, and then the amide intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF was 1 mol: 1 mol: 18 g: 7 g: 400 mL;

[0057] a2: Mix the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride and add them to a reactor, control the stirring reaction rate to 260r / min, heat to 46°C, stir and react for 4 hours, and then evaporate under reduced pressure to obtain an unsaturated amide intermediate; in the above reaction, the amount ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1 mol: 2 mol: 8 g: 500 mL;

[0058] a3: unsaturated amide intermediate, silica and 70% isopropanol solution were mixed and added into a reactor, the stirring reaction rate was controlled to be 800r / min, the temperature was raised to 64°C, and the mixture was stirred for 6 hours before being transferred to a drying oven, the temperature of the drying oven was controlled to be 90°C, and the toughening modifier was obtained after being dried for 2 hours; in the above reaction, the dosage ratio of unsaturated amide intermediate, silica and isopropanol was 18g:5g:100mL;

[0059] 2) Preparation of recycled polypropylene modified plastics

[0060] s1: 100 parts of recycled polypropylene, 18 parts of toughening modifier, 1.3 parts of initiator, 5 parts of compatibilizer, 2 parts of antioxidant, 2 parts of light stabilizer and 3 parts of lubricant were mixed and added into a mixer, the mixing temperature was controlled to be 160°C, and the compound was obtained after mixing for 1 hour;

[0061] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 210°C, 220°C, 230°C, 240°C, 240°C, 230°C, applying 70r / min, and the extrusion mass flow rate is 40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0062] Example 5

[0063] The specific implementation process of preparing a wear-resistant modified plastic in this embodiment is as follows:

[0064] 1) Preparation of toughening modifier

[0065] a1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reactor, the stirring reaction rate was controlled to be 380r / min, the temperature was raised to 29°C, and the stirring reaction was performed for 5 hours, and then the amide intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF was 1 mol: 1 mol: 18g: 7g: 400mL;

[0066] a2: Mix the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride and add them to a reactor, control the stirring reaction rate to 280r / min, heat to 48°C, stir and react for 4h, and then evaporate under reduced pressure to obtain an unsaturated amide intermediate; in the above reaction, the amount ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1mol:2mol:8g:500mL;

[0067] a3: unsaturated amide intermediate, silica and 70% isopropanol solution were mixed and added into a reactor, the stirring reaction rate was controlled to be 800r / min, the temperature was raised to 65°C, and the mixture was stirred for 6 hours before being transferred into a drying oven, the temperature of the drying oven was controlled to be 90°C, and the toughening modifier was obtained after being dried for 2 hours; in the above reaction, the dosage ratio of unsaturated amide intermediate, silica and isopropanol was 19g:5g:100mL;

[0068] 2) Preparation of recycled polypropylene modified plastics

[0069] s1: 100 parts of recycled polypropylene, 19 parts of toughening modifier, 1.4 parts of initiator, 5 parts of compatibilizer, 2 parts of antioxidant, 2 parts of light stabilizer and 3 parts of lubricant were mixed and added into a mixer, the mixing temperature was controlled to be 160°C, and the compound was obtained after mixing for 1 hour;

[0070] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 210°C, 220°C, 230°C, 240°C, 240°C, 230°C, applying 70r / min, and the extrusion mass flow rate is 40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0071] Example 6

[0072] The specific implementation process of preparing a wear-resistant modified plastic in this embodiment is as follows:

[0073] 1) Preparation of toughening modifier

[0074] a1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added into a reactor, the stirring reaction rate was controlled to be 400 r / min, the temperature was raised to 30°C, and the stirring reaction was performed for 5 hours, and then the amide intermediate was obtained by rotary evaporation under reduced pressure; in the above reaction, the amount ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF was 1 mol: 1 mol: 18 g: 7 g: 400 mL;

[0075] a2: Take the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride, mix them and feed them into a reactor, control the stirring reaction rate to 300r / min, heat to 50°C, stir and react for 4h, and then evaporate under reduced pressure to obtain the unsaturated amide intermediate; in the above reaction, the amount ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1mol:2mol:8g:500mL;

[0076] a3: unsaturated amide intermediate, silica and 70% isopropanol solution were mixed and added into a reactor, the stirring reaction rate was controlled to be 800r / min, the temperature was raised to 65°C, and the mixture was stirred for 6 hours before being transferred into a drying oven, the temperature of the drying oven was controlled to be 90°C, and the toughening modifier was obtained after being dried for 2 hours; in the above reaction, the dosage ratio of unsaturated amide intermediate, silica and isopropanol was 20g:5g:100mL;

[0077] 2) Preparation of recycled polypropylene modified plastics

[0078] s1: 100 parts of recycled polypropylene, 20 parts of toughening modifier, 1.5 parts of initiator, 5 parts of compatibilizer, 2 parts of antioxidant, 2 parts of light stabilizer and 3 parts of lubricant were mixed and added into a mixer, the mixing temperature was controlled at 160°C, and the compound was obtained after mixing for 1 hour;

[0079] Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 210°C, 220°C, 230°C, 240°C, 240°C, 230°C, applying 70r / min, and the extrusion mass flow rate is 40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

[0080] Comparative Example 1:

[0081] This comparative example uses PP recycled materials from Laizhou Yuanfang Plastic Industry Co., Ltd.

[0082] Comparative Example 2:

[0083] The specific implementation process of preparing a recycled polypropylene modified plastic in this comparative example is as follows:

[0084] s1: 100 parts of recycled polypropylene, 20 parts of acrylamide, 1.5 parts of initiator, 5 parts of silicon dioxide, 0.2 parts of silane coupling agent (KH-550 is selected in this comparative example), 5 parts of compatibilizer, 2 parts of antioxidant, 2 parts of light stabilizer and 3 parts of lubricant are mixed and added into a mixer, the mixing temperature is controlled to be 160° C., and the compound is obtained after mixing for 1 hour;

[0085] s2: Add the compound materials into the twin-screw extruder, adjust the temperature of each zone of the twin-screw to 210℃, 220℃, 230℃, 240℃, 240℃, 230℃, apply 70r / min, extrusion mass flow rate is 40kg / h, melt blending, extrusion and granulation to obtain recycled polypropylene modified plastic.

[0086] Bending strength and impact performance tests:

[0087] The recycled polypropylene modified plastics prepared in Examples 1-6 and Comparative Examples 1-2 were used to prepare specimens according to GB / T9341-2000 and GB / T1043.1-2008 and tested;

[0088] Self-healing bending strength and impact performance test:

[0089] The recycled polypropylene modified plastics prepared in Examples 1-6 and Comparative Examples 1-2 were prepared into specimens according to GB / T9341-2000 and GB / T1043.1-2008, and subjected to a DSR self-healing experiment. The experiment adopted a stress control method, the experimental temperature was 20°C, the loading frequency was 10Hz, and the fatigue stress was set to 0.5Mpa. When the initial complex shear modulus dropped to 60% of the fatigue damage, the loading was stopped for 30 minutes, and then the test was repeated 50 times, and the bending strength and impact performance tests were performed again. The specific test data are shown in Table 1:

[0090] Table 1

[0091]

[0092] From the data in Table 1, it can be seen that the flexural strength of the recycled polypropylene modified plastics prepared in Examples 1-6 is 29.82-30.05Mpa, and the impact strength is 26.57-26.66kJ / m 2 The bending strength and impact strength are higher than those of the recycled polypropylene modified plastic prepared in Comparative Examples 1-2. However, after 50 fatigue damage tests, the bending strength of the recycled polypropylene modified plastic prepared in Examples 1-6 is 25.35-25.54Mpa, and the impact strength is 22.05-22.15kJ / m 2 The strength loss rate is no more than 17%, compared with the strength loss rate of more than 45% in Comparative Examples 1-2. The recycled polypropylene modified plastic prepared in this embodiment shows good self-healing properties.

[0093] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0094] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A recycled polypropylene modified plastic, characterized in that: The composition comprises 100 parts of recycled polypropylene, 15-20 parts of toughening modifier, 1-1.5 parts of initiator, 3-5 parts of compatibilizer, 1-2 parts of antioxidant, 1-2 parts of light stabilizer and 2-3 parts of lubricant according to weight parts; Preparation of the toughening modifier: Step A1: dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF were mixed and added, the temperature was raised to 25-30° C., stirred for reaction for 3-5 hours, and then vacuum evaporated to obtain an amide intermediate; Step A2: Mix the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride, raise the temperature to 40-50° C., stir and react for 3-4 hours, and then evaporate under reduced pressure to obtain the unsaturated amide intermediate; Step A3: Take the unsaturated amide intermediate, silicon dioxide and isopropanol solution, mix them and add them, heat them to 60-65° C., stir and react for 6 hours, then transfer them to a drying oven, and dry them for 2 hours to obtain a toughening modifier.

2. A recycled polypropylene modified plastic according to claim 1, characterized in that: In step A1, the usage ratio of dimethylolpropionic acid, 3-aminopropyltriethoxysilane, DCC, DMAP and THF is 1 mol: 1 mol: 15-18 g: 7 g: 400 mL.

3. A recycled polypropylene modified plastic according to claim 2, characterized in that: In step A2, the usage ratio of the amide intermediate, allyl chloride, sodium hydroxide and ethylene dichloride is 1 mol:2 mol:5-8 g:500 mL.

4. A recycled polypropylene modified plastic according to claim 3, characterized in that: In step A3, the usage ratio of the unsaturated amide intermediate, silica and isopropanol is 15-20 g:5 g:100 mL.

5. The method for preparing a recycled polypropylene modified plastic according to claim 4, characterized in that: Prepared by the following method: Step S1: mixing recycled polypropylene, toughening modifier, initiator, compatibilizer, antioxidant, light stabilizer and lubricant, and mixing for 1 hour to obtain a batch; Step S2: adding the compound materials into a twin-screw extruder, adjusting the temperature of each zone of the twin-screw to 200-210°C, 210-220°C, 220-240°C, 240-250°C, 240-250°C, 220-230°C, applying 60-70r / min, and an extrusion mass flow rate of 30-40kg / h, melt blending, extrusion, and granulation to obtain recycled polypropylene modified plastic.

6. The method for preparing a recycled polypropylene modified plastic according to claim 5, characterized in that: AIBN initiator was selected as the initiator.

7. The method for preparing a recycled polypropylene modified plastic according to claim 6, characterized in that: The antioxidant is antioxidant 1010.

8. The method for preparing a recycled polypropylene modified plastic according to claim 7, characterized in that: The lubricant is zinc stearate.

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