Thermally reversible super-tough modified polypropylene and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to thermally reversible super-tough modified polypropylene and a preparation method thereof.The preparation method of the thermally reversible super-tough modified polypropylene comprises the following steps that pre-irradiated polypropylene, syndiotactic 1, 2 polybutadiene resin and an antioxidant are mixed to react, and polybutadiene modified polypropylene is obtained; epoxidizing a carbon-carbon double bond part in the polybutadiene modified polypropylene to prepare epoxidized polybutadiene modified polypropylene; preparing polybutadiene modified polypropylene from the epoxidized polybutadiene modified polypropylene; and blending and extruding the polybutadiene modified polypropylene and bismaleimide to obtain the thermally reversible super-tough modified polypropylene. The preparation method has the beneficial effects that the polypropylene containing the thermally reversible dynamic covalent bond is prepared, high-temperature fracture of the thermally reversible dynamic covalent bond is utilized to ensure good processability, and low-temperature crosslinking is performed, so that the system has good toughness while the strength is ensured, and the super-tough polypropylene is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a thermally reversible super-tough modified polypropylene and a preparation method thereof. Background Art

[0002] Polypropylene is one of the most widely used plastics. Although it has many excellent properties, it also has many disadvantages, such as poor toughness and impact resistance, which limits its use. There are many toughening methods, but the increase in toughness is accompanied by a decrease in strength, which in turn affects the decrease in wear resistance.

[0003] A Chinese invention patent with publication number CN 111484676 A discloses a polypropylene with improved toughness and a preparation method thereof, belonging to the field of polymer technology. The technical key points include the following components in parts by weight: 55-65 parts of polypropylene; 5-15 parts of modified nano carbon spheres; 0.2-0.5 parts of antioxidants; and 1-1.5 parts of composite lubricants. The modified nano carbon spheres are prepared by the following steps: S1, irradiating 2-5 parts of polyethylene with gamma rays having an irradiation dose of 20-30 kGy to obtain gamma-polyethylene; S2, adding the gamma-polyethylene and 10-80 parts of polyethylene into a stirrer, premixing them evenly, and then adding them into a twin-screw extruder for reaction extrusion, and then cooling them in a water bath and drying them with hot air, cutting and collecting the materials to obtain long-chain branched polyethylene; S3, adding the prepared long-chain branched polyethylene and 40-60 parts of nano carbon spheres into a torque rheometer, heating them to 140-170°C, maintaining a constant temperature and stirring them at a rotation speed of 6-80 r / min for 10-20 minutes, cooling them, and obtaining modified nano carbon spheres. The above technical solution is costly and the toughness of the modified polypropylene obtained is still not strong enough. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method of heat-reversible super-tough modified polypropylene having good toughness while ensuring strength and the heat-reversible super-tough modified polypropylene.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: to provide a method for preparing a thermally reversible super-tough modified polypropylene, comprising the following steps: (1) Preparation of pre-irradiated polypropylene; (2) mixing the pre-irradiated polypropylene with 1,2-polybutadiene syndiotactic resin and an antioxidant to obtain polybutadiene-modified polypropylene; (3) epoxidizing part of the carbon-carbon double bonds in the polybutadiene-modified polypropylene to prepare epoxidized polybutadiene-modified polypropylene; (4) The epoxidized polybutadiene modified polypropylene is reacted with furfurylamine and extruded to obtain polybutadiene modified polypropylene with furan groups; and the polybutadiene modified polypropylene is blended with bismaleimide and extruded to obtain thermally reversible super-tough modified polypropylene.

[0006] Furthermore, in the above-mentioned method for preparing the thermally reversible super-tough modified polypropylene, the step (1) is specifically: irradiating the polypropylene powder for 0.1h to 1h at an irradiation dose of 0.5kGy to 5kGy to obtain pre-irradiated polypropylene.

[0007] Furthermore, in the above-mentioned method for preparing the thermally reversible super-tough modified polypropylene, the step (2) is specifically: adding the pre-irradiated polypropylene, the syndiotactic 1,2-polybutadiene resin and the antioxidant into a high-speed mixer, mixing them fully at high speed, and reacting and extruding them through an extruder to prepare the polybutadiene-modified polypropylene.

[0008] Furthermore, in the method for preparing the above-mentioned thermally reversible super-tough modified polypropylene, the weight ratio of the pre-irradiated polypropylene, the syndiotactic 1,2-polybutadiene resin and the antioxidant in the step (2) is: 50-90:5-40:0.5-5.

[0009] Furthermore, in the above-mentioned method for preparing the thermally reversible super-tough modified polypropylene, the step (3) is specifically as follows: The polybutadiene-modified polypropylene is dissolved in toluene, and then heated to 60-70° C., and then formic acid and hydrogen peroxide solution are added successively to perform epoxidation reaction to obtain epoxide. After the reaction is completed, the epoxide is precipitated using anhydrous ethanol, and the precipitate is dried to remove the solvent to obtain epoxidized polybutadiene-modified polypropylene.

[0010] Furthermore, in the above-mentioned method for preparing the thermally reversible super-tough modified polypropylene, the step (4) is specifically as follows: The epoxidized polybutadiene-modified polypropylene and toluene are added into a three-necked flask respectively, the temperature of the oil bath heating furnace is set to 40-50° C., and furfurylamine is added for reaction to obtain furfurylamine-grafted polybutadiene-modified polypropylene; Adding the furfurylamine grafted polybutadiene modified polypropylene to a tetrahydrofuran solution and heating to remove unreacted furfurylamine, and then placing the solution in an oven for baking to remove the solvent; Then, bismaleimide having the same molar number as the furfurylamine is added into an internal mixer and blended, and then placed in an oven for baking to remove the solvent, thereby obtaining a thermally reversible super-tough modified polypropylene.

[0011] Another technical solution of the present invention is to provide a thermally reversible super-tough modified polypropylene prepared by the preparation method of the thermally reversible super-tough modified polypropylene.

[0012] The beneficial effects of the present invention are as follows: the present invention prepares polypropylene containing thermally reversible dynamic covalent bonds, utilizes the high temperature fracture of the thermally reversible dynamic bonds to ensure good processing performance, and crosslinks at low temperature, so that the system has good toughness while ensuring strength, thereby obtaining super-tough polypropylene. Specifically: the method adopts irradiation and melt reaction extrusion technology to melt graft polypropylene with polybutadiene to prepare polybutadiene-modified polypropylene. The carbon-carbon (C=C) double bonds in the polybutadiene-modified polypropylene are partially epoxidized to prepare epoxidized polybutadiene-modified polypropylene. The epoxidized polybutadiene-modified polypropylene is then reacted and extruded with furfurylamine to prepare polybutadiene-modified polypropylene with furan groups. Finally, the polybutadiene-modified polypropylene with furan groups is blended and extruded with bismaleimide to prepare modified polypropylene with thermally reversible dynamic covalent bonds to obtain super-tough polypropylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The infrared images of PP-g-PB and epoxidized EPP-g-PB of Example 3 of the specific embodiment of the present invention; Figure 2 The infrared images of the epoxidized EPP-g-PB and the furfurylamine-grafted FA-PP-g-PB of Example 3 of the specific embodiment of the present invention; Figure 3 It is the DSC test peak value of Example 3 of the specific embodiment of the present invention; DETAILED DESCRIPTION

[0014] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0015] Example 1

[0016] A method for preparing thermally reversible super-tough modified polypropylene comprises the following steps: (1) Preparing pre-irradiated polypropylene: irradiating polypropylene powder (brand: T30S; manufacturer: Sinopec Maoming) at an irradiation dose of 0.5 kGy for 0.3 h to obtain pre-irradiated polypropylene.

[0017] (2) The pre-irradiated polypropylene, syndiotactic 1,2-polybutadiene resin (brand name: JSR:830; manufacturer: Japan Co., Ltd.) and antioxidant (brand name: Irganox 168; manufacturer: BASF) are added to a high-speed mixer, fully mixed at high speed, and reacted and extruded through an extruder to prepare polybutadiene-modified polypropylene. The weight ratio of the pre-irradiated polypropylene, syndiotactic 1,2-polybutadiene resin and antioxidant in step (2) is 50:5:0.5.

[0018] The mixture was fully mixed at high speed (100 r / min, 30 mins) and subjected to reaction extrusion through an extruder. The reaction extrusion granulation process parameters were: extrusion temperature 175-185°C, melt temperature 185°C, extrusion speed 15 r / min, cooling water temperature 15°C, and polybutadiene modified polypropylene (PP-g-PB) was prepared.

[0019] (3) Preparation of epoxidized polybutadiene modified polypropylene; In a 250 mL three-necked flask, 10 g of PP-g-PB and 100 mL of toluene were added respectively, and the PP-g-PB was dissolved in toluene by stirring at room temperature; then the three-necked flask was placed in an oil bath and heated to 70 °C, and then 5 mL of formic acid and 6 mL of 30 vol% hydrogen peroxide solution were added to the three-necked flask in sequence, and the reaction was carried out for 2 h.

[0020] After the epoxidation reaction is completed, the epoxidized polybutadiene modified polypropylene (EPP-g-PB) is precipitated with anhydrous ethanol, and the precipitate is placed in a drying oven at 80°C for 12 hours, and the solvent is removed to obtain the epoxidized polybutadiene modified polypropylene (EPP-g-PB).

[0021] (4) 5 g of epoxidized polybutadiene modified polypropylene (EPP-g-PB) and 50 mL of toluene were added into a 250 mL three-necked flask, respectively. The temperature of the oil bath heating furnace was set to 40 °C. A certain amount of furfurylamine (FA) (the molar ratio of furfurylamine group to epoxy group was 2:1) was added. The reaction was carried out for a certain time (3 hours. The reaction was terminated when the number of epoxy groups was detected by infrared testing) to obtain furfurylamine grafted polybutadiene modified polypropylene (FA-PP-g-PB).

[0022] The reacted furfurylamine grafted polybutadiene modified polypropylene (FA-PP-PB) was added with tetrahydrofuran solution and heated to remove unreacted furfurylamine, and then placed in an oven and baked at 85°C for 10 hours to remove the solvent.

[0023] Then, bismaleimide (BMI) with the same molar number as furfurylamine (FA) was added into an internal mixer and blended. At the same time, the system temperature was raised to 150°C, reacted for a certain time (5 minutes), and heat-treated at 120°C in an oven for 24 hours to remove the solvent, thereby obtaining reversible super-tough modified polypropylene (DPP-g-PB).

[0024] The thermally reversible super-tough modified polypropylene (DPP-g-PB) obtained in Example 1 has an Izod notched impact strength (23°C, GB / T1843-2008) of 83 J / m and an elongation at break (GB / T1040.2-2006) of 607%.

[0025] Example 2

[0026] A method for preparing thermally reversible super-tough modified polypropylene comprises the following steps: (1) Preparing pre-irradiated polypropylene: irradiating polypropylene powder (brand: T30S; manufacturer: Sinopec Maoming) at an irradiation dose of 5 kGy for 0.1 h to obtain pre-irradiated polypropylene.

[0027] (2) The pre-irradiated polypropylene, syndiotactic 1,2-polybutadiene resin (brand name: JSR:830; manufacturer: Japan Co., Ltd.) and antioxidant (brand name: Irganox 168; manufacturer: BASF) are added to a high-speed mixer, fully mixed at high speed, and reacted and extruded through an extruder to prepare polybutadiene-modified polypropylene. The weight ratio of the pre-irradiated polypropylene, syndiotactic 1,2-polybutadiene resin and antioxidant in step (2) is 90:40:5.

[0028] The mixture was fully mixed at high speed (100 r / min, 30 mins) and subjected to reaction extrusion through an extruder. The reaction extrusion granulation process parameters were: extrusion temperature 175-185°C, melt temperature 185°C, extrusion speed 15 r / min, cooling water temperature 15°C, and polybutadiene modified polypropylene (PP-g-PB) was prepared.

[0029] (3) Preparation of epoxidized polybutadiene modified polypropylene; In a 250 mL three-necked flask, 10 g of PP-g-PB and 100 mL of toluene were added respectively, and the PP-g-PB was dissolved in toluene by stirring at room temperature; then the three-necked flask was placed in an oil bath and heated to 70 °C, and then 5 mL of formic acid and 6 mL of 30 vol% hydrogen peroxide solution were added to the three-necked flask in sequence, and the reaction was carried out for 2 h.

[0030] After the epoxidation reaction is completed, the epoxidized polybutadiene modified polypropylene (EPP-g-PB) is precipitated with anhydrous ethanol, and the precipitate is placed in a drying oven at 80°C for 12 hours, and the solvent is removed to obtain the epoxidized polybutadiene modified polypropylene (EPP-g-PB).

[0031] (4) 5 g of epoxidized polybutadiene modified polypropylene (EPP-g-PB) and 50 mL of toluene were added into a 250 mL three-necked flask, respectively. The temperature of the oil bath heating furnace was set to 40 °C. A certain amount of furfurylamine (FA) (the molar ratio of furfurylamine group to epoxy group was 2:1) was added. The reaction was carried out for a certain time (3 hours. The reaction was terminated when the number of epoxy groups was detected by infrared testing) to obtain furfurylamine grafted polybutadiene modified polypropylene (FA-PP-g-PB).

[0032] The reacted furfurylamine grafted polybutadiene modified polypropylene (FA-PP-PB) was added with tetrahydrofuran solution and heated to remove unreacted furfurylamine, and then placed in an oven and baked at 85°C for 10 hours to remove the solvent.

[0033] Then, bismaleimide (BMI) with the same molar number as furfurylamine (FA) was added into an internal mixer and blended. At the same time, the system temperature was raised to 150°C, reacted for a certain time (5 minutes), and heat-treated at 120°C in an oven for 24 hours to remove the solvent, thereby obtaining reversible super-tough modified polypropylene (DPP-g-PB).

[0034] The thermally reversible super-tough modified polypropylene (DPP-g-PB) obtained in Example 2 has an Izod notched impact strength (23°C, GB / T1843-2008) of 87 J / m and an elongation at break (GB / T1040.2-2006) of 630%.

[0035] Example 3

[0036] A method for preparing thermally reversible super-tough modified polypropylene comprises the following steps: (1) Preparation of pre-irradiated polypropylene; Polypropylene powder (brand: T30S; manufacturer: Sinopec Maoming) was pre-irradiated, and the dose was controlled at 2 kGy. The pre-irradiated polypropylene powder was subjected to aerobic conditions to generate alkyl peroxide or alkyl hydroperoxide.

[0037] (2) Pre-irradiated polypropylene, syndiotactic 1,2-polybutadiene resin (brand name: JSR:830; manufacturer: Japan Co., Ltd.) and antioxidant (brand name: Irganox 1010; manufacturer: BASF) are added into a high-speed mixer, wherein the weight ratio of the pre-irradiated polypropylene, syndiotactic 1,2-polybutadiene resin and antioxidant is 60:25:3.

[0038] The mixture was fully mixed at high speed (100 r / min, 30 mins) and subjected to reaction extrusion through an extruder. The reaction extrusion granulation process parameters were: extrusion temperature 175-185°C, melt temperature 185°C, extrusion speed 15 r / min, cooling water temperature 15°C, and polybutadiene modified polypropylene (PP-g-PB) was prepared.

[0039] (3) Preparation of epoxidized polybutadiene modified polypropylene; In a 250 mL three-necked flask, 10 g of PP-g-PB and 100 mL of toluene were added respectively, and the PP-g-PB was dissolved in toluene by stirring at room temperature; then the three-necked flask was placed in an oil bath and heated to 70 °C, and then 5 mL of formic acid and 6 mL of 30 vol% hydrogen peroxide solution were added to the three-necked flask in sequence, and the reaction was carried out for 2 h.

[0040] After the epoxidation reaction is completed, the epoxidized polybutadiene modified polypropylene (EPP-g-PB) is precipitated with anhydrous ethanol, and the precipitate is placed in a drying oven at 80°C for 12 hours, and the solvent is removed to obtain the epoxidized polybutadiene modified polypropylene (EPP-g-PB).

[0041] (4) Preparation of thermally reversible super-tough modified polypropylene 10 g of epoxidized polybutadiene modified polypropylene (EPP-g-PB) and 100 mL of toluene were added into a 250 mL three-necked flask respectively, the temperature of the oil bath heating furnace was set to 45 °C, a certain amount of furfurylamine (FA) (the molar ratio of furfurylamine group to epoxy group was 2:1) was added, and the reaction was carried out for a certain time (3-5 hours, and the reaction was terminated when the epoxy group was detected by infrared testing) to obtain furfurylamine grafted polybutadiene modified polypropylene (FA-PP-g-PB).

[0042] The furfurylamine grafted polybutadiene modified polypropylene (FA-PP-PB) after the reaction was completed was added with tetrahydrofuran solution and heated to remove the unreacted furfurylamine, and then placed in an oven and baked at 80°C for 12 hours to remove the solvent.

[0043] Then, bismaleimide (BMI) with the same molar number as furfurylamine (FA) was added into an internal mixer and blended. At the same time, the system temperature was raised to 150°C, reacted for a certain time (7 minutes), and heat-treated at 130°C in an oven for 24 hours to remove the solvent, thereby obtaining reversible super-tough modified polypropylene (DPP-g-PB).

[0044] See also Figure 1-Figure 3 ; Figure 1 The infrared images of PP-g-PB and epoxidized EPP-g-PB in Example 3; Figure 2 The infrared images of the epoxidized EPP-g-PB and the furfurylamine-grafted FA-PP-g-PB of Example 3; Figure 3 It is the DSC test peak value of Example 3.

[0045] from Figure 1 It can be seen that the carbon-carbon double bond C=C is converted into the epoxy matrix COC. Figure 2 It can be seen that furfurylamine was successfully grafted onto the molecular chain and the epoxy matrix disappeared. Figure 3 It can be seen that the DA bond breaks at 147°C and the system forms a DA bond.

[0046] From the above description, infrared analysis shows that the pre-irradiation and grafting reaction occurred in the pre-irradiated blend prepared by reactive extrusion blending, forming a graft copolymer, and a thermally reversible covalent bond was formed in the system. The dynamic bond on the surface of the mechanical properties test can effectively improve the strength and toughness of the system.

[0047] The thermally reversible super-tough modified polypropylene (DPP-g-PB) obtained in Example 3 has an Izod notched impact strength (23°C, GB / T1843-2008) of 88 J / m, which is much higher than 34 J / m of pure PP. The elongation at break (GB / T1040.2-2006) is 612%, which is much higher than pure PP (T30s).

[0048] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a thermally reversible super-tough modified polypropylene, characterized in that: The steps include: (1) Preparation of pre-irradiated polypropylene; (2) mixing the pre-irradiated polypropylene with 1,2-polybutadiene syndiotactic resin and an antioxidant to obtain polybutadiene-modified polypropylene; (3) epoxidizing part of the carbon-carbon double bonds in the polybutadiene-modified polypropylene to prepare epoxidized polybutadiene-modified polypropylene; (4) The epoxidized polybutadiene modified polypropylene is reacted with furfurylamine and extruded to obtain polybutadiene modified polypropylene with furan groups; and the polybutadiene modified polypropylene is blended with bismaleimide and extruded to obtain thermally reversible super-tough modified polypropylene.

2. The method for preparing the thermally reversible super-tough modified polypropylene according to claim 1, characterized in that: The step (1) specifically comprises: irradiating the polypropylene powder for 0.1 h to 1 h at an irradiation dose of 0.5 kGy to 5 kGy to obtain pre-irradiated polypropylene.

3. The method for preparing the thermally reversible super-tough modified polypropylene according to claim 1, characterized in that: The step (2) specifically comprises: adding the pre-irradiated polypropylene, 1,2-polybutadiene syndiotactic resin and antioxidant into a high-speed mixer, mixing them fully at high speed, and performing reaction extrusion through an extruder to prepare polybutadiene-modified polypropylene.

4. The method for preparing the thermally reversible super-tough modified polypropylene according to claim 3, characterized in that: In the step (2), the weight ratio of the pre-irradiated polypropylene, the syndiotactic 1,2-polybutadiene resin and the antioxidant is 50-90:5-40:0.5-5.

5. The method for preparing the thermally reversible super-tough modified polypropylene according to claim 1, characterized in that: The step (3) is specifically as follows: The polybutadiene-modified polypropylene is dissolved in toluene, and then heated to 60-70° C., and then formic acid and hydrogen peroxide solution are added successively to perform epoxidation reaction to obtain epoxide. After the reaction is completed, the epoxide is precipitated using anhydrous ethanol, and the precipitate is dried to remove the solvent to obtain epoxidized polybutadiene-modified polypropylene.

6. The method for preparing the thermally reversible super-tough modified polypropylene according to claim 1, characterized in that: The step (4) is specifically as follows: The epoxidized polybutadiene-modified polypropylene and toluene are added into a three-necked flask respectively, the temperature of the oil bath heating furnace is set to 40-50° C., and furfurylamine is added for reaction to obtain furfurylamine-grafted polybutadiene-modified polypropylene; Adding the furfurylamine grafted polybutadiene modified polypropylene to a tetrahydrofuran solution and heating to remove unreacted furfurylamine, and then placing the solution in an oven for baking to remove the solvent; Then, bismaleimide having the same molar number as the furfurylamine is added into an internal mixer and blended, and then placed in an oven for baking to remove the solvent, thereby obtaining a thermally reversible super-tough modified polypropylene.

7. Thermoreversible super-tough modified polypropylene prepared according to the method for preparing thermoreversible super-tough modified polypropylene according to any one of claims 1 to 6.

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