Thermoplastic material as well as preparation method and application thereof in automotive trim

Abstract

The invention discloses a thermoplastic material as well as a preparation method and application thereof in automotive trim, and relates to the technical field of high polymer materials. When the thermoplastic material is prepared, cellulose is sequentially reacted with 4-isocyanate-2, 2, 6, 6-tetramethyl-1-piperidyloxy and vinyl phosphonic acid bis (2-chloroethyl ester), and modified cellulose is prepared; the preparation method comprises the following steps: reacting 4-hydroxy-1, 8-naphthalic anhydride with 1-amino-5-hexene to obtain a naphthalimide monomer; the preparation method comprises the following steps: reacting polypropylene, a siloxane imidazole monomer and a naphthalimide monomer to prepare pre-modified polypropylene; reacting the pre-modified polypropylene with paraformaldehyde to obtain modified polypropylene; uniformly mixing the modified polypropylene and the modified cellulose, extruding and granulating to obtain the thermoplastic material. The thermoplastic material prepared by the invention has excellent flame retardance, aging resistance, antibacterial property, mechanical property and thermal reversible self-repairing property.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a thermoplastic material, a preparation method thereof, and an application thereof in automotive interiors. Background Art

[0002] Polypropylene and its modified materials are widely used in automotive interiors, mainly covering seats, floors, instrument panels and central control areas, door interiors, functional structural parts, etc. Polypropylene can be used as the filling material of seats, or as the skeleton and surface layer materials of seats, with high comfort and durability; polypropylene can be used as the carpet material of automobiles, with the functions of sound absorption, heat insulation, and easy cleaning; polypropylene can also be used to produce components such as the main body of the automotive instrument panel, the central passage structural part, the roof interior, and the storage box.

[0003] Automotive interior materials are directly related to the comfort, safety, and service life of passengers. As a polymer material, polypropylene has the advantages of low cost, light weight, and easy processing that are difficult to replace by metal materials. At the same time, it generally has the defects of flammability, easy aging, and low strength. Therefore, it is necessary to improve the existing technology, overcome the defects of polypropylene such as flammability, easy aging, and low strength, give full play to the excellent performance of polypropylene, improve the comfort and safety of automobiles, and extend the service life of automobiles. Summary of the Invention

[0004] The purpose of the present invention is to provide a thermoplastic material, a preparation method thereof, and an application thereof in automotive interiors to solve the problems existing in the prior art.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A thermoplastic material is prepared by reacting pre-modified cellulose with bis(2-chloroethyl) vinylphosphonate to obtain modified cellulose; reacting polypropylene, a siloxane imidazole monomer, and a naphthalimide monomer to obtain pre-modified polypropylene; reacting the pre-modified polypropylene with paraformaldehyde to obtain modified polypropylene; and mixing the modified polypropylene and the modified cellulose evenly and then extruding and pelletizing.

[0007] The pre-modified cellulose is obtained by reacting cellulose with 4-isocyanato-2,2,6,6-tetramethyl-1-piperidinyloxy.

[0008] The siloxane imidazole monomer is obtained by reacting imidazole with 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane.

[0009] The naphthalimide monomer is obtained by reacting 4-hydroxy-1,8-naphthalic anhydride with 1-amino-5-hexene.

[0010] A preparation method of a thermoplastic material, the preparation method of the thermoplastic material comprising the following preparation steps:

[0011] (1) Mix uniformly pre-modified fibers, bis(2-chloroethyl) vinylphosphonate, benzoyl peroxide, and toluene at a mass ratio of 1:(2 - 3):(0.03 - 0.05):(20 - 24). Under a nitrogen atmosphere, stir and react at 75 - 85°C and 200 - 300 r / min for 3 - 4 h. Under vacuum conditions, dry at 50 - 60°C for 7 - 8 h to obtain modified cellulose;

[0012] (2) Place polypropylene in a mixer. Plasticize at 178 - 180°C and 50 - 60 r / min for 6 - 8 min. Add a siloxane imidazole monomer in an amount 0.03 - 0.04 times the mass of polypropylene, add a naphthalimide monomer in an amount 0.02 - 0.03 times the mass of polypropylene, continue plasticizing for 4 - 6 min, add diisopropylbenzene peroxide in an amount 0.0003 - 0.0005 times the mass of polypropylene, continue plasticizing for 10 - 12 min, and cool to room temperature to obtain pre-modified polypropylene. Mix uniformly pre-modified polypropylene, magnesium chloride, and xylene at a mass ratio of 1:(0.002 - 0.003):(9 - 11). Stir at 128 - 132°C and 50 - 60 r / min for 10 - 12 min, cool down to 90 - 92°C, add trimethylamine in an amount 0.001 - 0.002 times the mass of pre-modified polypropylene, continue stirring for 8 - 10 min, add paraformaldehyde in an amount 0.03 - 0.04 times the mass of pre-modified polypropylene, continue stirring and reacting for 2 - 3 h, adjust the pH to 5.5 - 6.5 with a 5% hydrochloric acid aqueous solution, and dry at 70 - 80°C under vacuum conditions for 9 - 11 h to obtain modified polypropylene;

[0013] (3) Mix uniformly modified polypropylene, modified cellulose, and xylene at a mass ratio of 1:(0.06 - 0.08):(8 - 10). Stir at 128 - 132°C and 50 - 60 r / min for 10 - 12 min, cool down to 70 - 80°C, continue stirring for 16 - 18 min, dry at 70 - 80°C under vacuum conditions for 12 - 14 h, and extrude and pelletize in a screw extruder to obtain the thermoplastic material.

[0014] As an optimization, the preparation method of the pre-modified cellulose in step (1) is as follows: Mix cellulose, anhydrous lithium chloride, and N,N-dimethylformamide evenly according to a mass ratio of 1:(0.2 - 0.3):(26 - 28), stir at 70 - 80°C and 200 - 300 r / min for 20 - 30 min, cool down to 40 - 50°C, add 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy which is 1.2 - 1.4 times the mass of the fiber, and dibutyltin dilaurate which is 0.03 - 0.05 times the mass of the cellulose, continue to stir and react for 1 - 2 h, and dry at 40 - 50°C under vacuum conditions for 6 - 7 h to obtain the pre-modified cellulose.

[0015] As an optimization, the molecular weight of the cellulose is 20,000.

[0016] As an optimization, the CAS number of 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy in step (1) is 88418-69-3, and its structural formula is:

[0017] As an optimization, the preparation method of the siloxane imidazole monomer in step (2) is as follows: Mix imidazole, sodium hydroxide, and acetonitrile evenly according to a mass ratio of 1:(0.1 - 0.12):(14 - 16), stir at 10 - 30°C and 200 - 300 r / min for 10 - 20 min under argon protection, add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane with an equimolar amount of imidazole, raise the temperature to 55 - 65°C, continue to stir and react for 5 - 6 h, and dry at 60 - 70°C under vacuum conditions for 8 - 10 h to obtain the siloxane imidazole monomer; the reaction process is as follows:

[0018]

[0019] As an optimization, the preparation method of the naphthalimide monomer in step (2) is as follows: Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol evenly according to a mass ratio of 1:(10 - 12), stir at 48 - 52°C and 200 - 300 r / min for 10 - 20 min under nitrogen protection, add 1-amino-5-hexene with an equimolar amount of 4-hydroxy-1,8-naphthalic anhydride, raise the temperature to 74 - 76°C, continue to stir and react for 10 - 12 h, cool to room temperature, add deionized water which is 2 - 2.2 times the volume of absolute ethanol, let it stand for 1 - 2 h, filter, and dry at 50 - 60°C under vacuum conditions for 8 - 10 h to obtain the naphthalimide monomer; the reaction process is as follows:

[0020]

[0021] As an optimization, the model of the polypropylene in step (2) is K8303.

[0022] As an optimization, the degree of polymerization of paraformaldehyde described in step (2) is 8 - 12.

[0023] As an optimization, the process parameters of the extrusion granulation described in step (3) are: the temperature of the screw extruder is set at 180 - 190 °C, and the screw speed is 80 - 100 r / min.

[0024] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0025] When preparing the thermoplastic material of the present invention, cellulose and 4 - isocyanate - 2,2,6,6 - tetramethyl - 1 - piperidinyloxy are reacted to obtain pre - modified cellulose; the pre - modified cellulose and bis(2 - chloroethyl) vinylphosphonate are reacted to obtain modified cellulose; imidazole and 1 - vinyl - 3 - chloromethyl - 1,1,3,3 - tetramethyldisiloxane are reacted to obtain a siloxane imidazole monomer; 4 - hydroxy - 1,8 - naphthalic anhydride and 1 - amino - 5 - hexene are reacted to obtain a naphthalimide monomer; polypropylene, the siloxane imidazole monomer, and the naphthalimide monomer are reacted to obtain pre - modified polypropylene; the pre - modified polypropylene and paraformaldehyde are reacted to obtain modified polypropylene; the modified polypropylene and the modified cellulose are uniformly mixed and extruded and granulated to obtain the thermoplastic material.

[0026] First, cellulose and 4 - isocyanate - 2,2,6,6 - tetramethyl - 1 - piperidinyloxy are reacted to obtain pre - modified cellulose, and a piperidine - based nitroxide radical is introduced onto the pre - modified cellulose; the double bond on bis(2 - chloroethyl) vinylphosphonate reacts with the piperidine - based nitroxide radical introduced onto the pre - modified cellulose to obtain modified cellulose; an alkoxyamine bond is formed on the modified cellulose, and at the same time, phosphorus element and chlorine atoms are introduced; the introduction of the phosphorus element can improve the flame - retardant performance of the thermoplastic material, and the chlorine atoms can react with the alkyl imidazole introduced on the side chain of the modified polypropylene molecule to form an imidazole salt, forming a cross - linked network structure, which inhibits the relative slippage between the polypropylene molecular chains, improves the mechanical properties of the thermoplastic material, and at the same time, the generated imidazole salt has antibacterial properties, which can improve the antibacterial performance of the thermoplastic material; during the cross - linking process, an alkoxyamine bond is also introduced between the modified cellulose and the modified polypropylene. The alkoxyamine bond is a thermoreversible chemical bond, which breaks at high temperature to generate nitroxide radicals and carbon radicals, and re - bonds at low temperature to form a new alkoxyamine bond, thereby endowing the thermoplastic material with thermoreversible self - healing performance. The mechanism is as follows:

[0027]

[0028] Secondly, the siloxane imidazole monomer is prepared by reacting imidazole with 1 - vinyl - 3 - chloromethyl - 1,1,3,3 - tetramethyldisiloxane; the naphthalimide monomer is prepared by reacting 4 - hydroxy - 1,8 - naphthalic anhydride with 1 - amino - 5 - hexene; the carbon - carbon double bonds on the siloxane imidazole monomer and the naphthalimide monomer are grafted onto the side chain of the polypropylene molecule by melt grafting method to obtain pre - modified polypropylene; Si - O - Si bonds, alkyl imidazole and 4 - hydroxy - 1,8 - naphthalimide structures are introduced onto the side chain of the pre - modified polypropylene molecule; the introduction of Si - O - Si bonds can improve the flame - retardant performance of thermoplastic materials, and the alkyl imidazole can react with the chlorine atoms introduced on the modified cellulose to generate imidazolium salts, forming a cross - linked network structure, inhibiting the relative slippage between the polypropylene molecular chains, improving the mechanical properties of thermoplastic materials, and at the same time, the generated imidazolium salts also have antibacterial properties, improving the antibacterial performance of thermoplastic materials; 4 - hydroxy - 1,8 - naphthalimide on the pre - modified polypropylene reacts with paraformaldehyde to obtain modified polypropylene, and an o - hydroxy naphthalimide formaldehyde structure is formed on the modified polypropylene. The o - hydroxy naphthalimide formaldehyde structure can undergo a ring - opening and closing reaction under the alternating action of ultraviolet light and visible light, thereby absorbing ultraviolet light and releasing it in a harmless form, improving the anti - aging performance of thermoplastic materials. The mechanism of action is as follows:

[0029] Specific embodiments

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Example 1:

[0032] A preparation method of a thermoplastic material, the preparation method of the thermoplastic material includes the following preparation steps:

[0033] (1) Mix cellulose, lithium chloride anhydrous, and N,N-dimethylformamide evenly at a mass ratio of 1:0.2:26. Stir at 70 °C and 200 r / min for 30 min, then cool down to 40 °C. Add 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy which is 1.2 times the mass of the fiber, and dibutyltin dilaurate which is 0.03 times the mass of the cellulose. Continue stirring and reacting for 2 h, and then dry at 40 °C under vacuum for 7 h to obtain pre-modified cellulose. Mix the pre-modified fiber, bis(2-chloroethyl) vinylphosphonate, benzoyl peroxide, and toluene evenly at a mass ratio of 1:2:0.03:20. Stir and react at 75 °C and 200 r / min for 4 h under a nitrogen atmosphere, and then dry at 50 °C under vacuum for 8 h to obtain modified cellulose;

[0034] (2) Mix imidazole, sodium hydroxide, and acetonitrile evenly at a mass ratio of 1:0.1:14. Stir at 10 °C and 200 r / min for 20 min under argon protection, then add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane which is equimolar to imidazole, and raise the temperature to 55 °C. Continue stirring and reacting for 6 h, and then dry at 60 °C under vacuum for 10 h to obtain a siloxane imidazole monomer. Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol evenly at a mass ratio of 1:10. Stir at 48 °C and 200 r / min for 20 min under nitrogen protection, then add 1-amino-5-hexene which is equimolar to 4-hydroxy-1,8-naphthalic anhydride, and raise the temperature to 74 °C. Continue stirring and reacting for 12 h, cool to room temperature, add deionized water which is 2 times the volume of absolute ethanol, let it stand for 1 h, filter, and dry at 50 °C under vacuum for 10 h to obtain a naphthalimide monomer. Place polypropylene in a mixer and plasticate at 178 °C and 50 r / min for 8 min, add the siloxane imidazole monomer which is 0.03 times the mass of polypropylene, add the naphthalimide monomer which is 0.02 times the mass of polypropylene, continue plasticating for 6 min, add dicumyl peroxide which is 0.0003 times the mass of polypropylene, continue plasticating for 12 min, and then cool to room temperature to obtain pre-modified polypropylene. Mix the pre-modified polypropylene, magnesium chloride, and xylene evenly at a mass ratio of 1:0.002:9. Stir at 128 °C and 50 r / min for 12 min, then cool down to 90 °C, add trimethylamine which is 0.001 times the mass of the pre-modified polypropylene, continue stirring for 10 min, add paraformaldehyde with a polymerization degree of 8 which is 0.03 times the mass of the pre-modified polypropylene, continue stirring and reacting for 3 h, adjust the pH to 5.5 with a 5% hydrochloric acid aqueous solution, and dry at 70 °C under vacuum for 11 h to obtain modified polypropylene;

[0035] (3) Mix the modified polypropylene, modified cellulose, and xylene evenly at a mass ratio of 1:0.06:8, stir at 128 °C and 50 r / min for 12 min, cool down to 70 °C, continue stirring for 18 min, dry at 70 °C for 14 h under vacuum conditions, and then extrude and pelletize in a screw extruder. Set the temperature of the screw extruder to 180 °C and the screw speed to 80 r / min to obtain the thermoplastic material.

[0036] Example 2:

[0037] A preparation method of a thermoplastic material, the preparation method of the thermoplastic material comprising the following preparation steps:

[0038] (1) Mix cellulose, anhydrous lithium chloride, and N,N-dimethylformamide evenly at a mass ratio of 1:0.25:27, stir at 75 °C and 250 r / min for 25 min, cool down to 45 °C, add 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy which is 1.3 times the mass of the fiber, and dibutyltin dilaurate which is 0.04 times the mass of the cellulose, and continue stirring and reacting for 1.5 h. Dry at 45 °C for 6.5 h under vacuum conditions to obtain pre-modified cellulose; Mix the pre-modified fiber, bis(2-chloroethyl) vinylphosphonate, benzoyl peroxide, and toluene evenly at a mass ratio of 1:2.5:0.04:22, stir and react at 80 °C and 250 r / min for 3.5 h in a nitrogen atmosphere, and dry at 55 °C for 7.5 h under vacuum conditions to obtain modified cellulose;

[0039] (2) Mix imidazole, sodium hydroxide, and acetonitrile evenly at a mass ratio of 1:0.11:15. Under argon protection, stir at 20 °C and 250 r / min for 15 min. Add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane in an equimolar amount of imidazole, heat up to 60 °C, and continue stirring and reacting for 5.5 h. Under vacuum conditions, dry at 65 °C for 9 h to obtain a siloxane imidazole monomer; Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol evenly at a mass ratio of 1:11. Under nitrogen protection, stir at 50 °C and 250 r / min for 15 min. Add 1-amino-5-hexene in an equimolar amount of 4-hydroxy-1,8-naphthalic anhydride, heat up to 75 °C, and continue stirring and reacting for 11 h. Cool to room temperature, add deionized water in an amount 2.1 times the volume of absolute ethanol, let stand for 1.5 h, filter, and dry at 55 °C for 9 h under vacuum conditions to obtain a naphthalimide monomer; Place polypropylene in a mixer and knead at 179 °C and 55 r / min for 7 min. Add a siloxane imidazole monomer in an amount 0.035 times the mass of polypropylene, add a naphthalimide monomer in an amount 0.025 times the mass of polypropylene, continue kneading for 5 min, add diisopropylbenzene peroxide in an amount 0.0004 times the mass of polypropylene, continue kneading for 11 min, and cool to room temperature to obtain pre-modified polypropylene; Mix pre-modified polypropylene, magnesium chloride, and xylene evenly at a mass ratio of 1:0.0025:10. Stir at 130 °C and 55 r / min for 11 min, cool down to 91 °C, add trimethylamine in an amount 0.0015 times the mass of pre-modified polypropylene, continue stirring for 9 min, add paraformaldehyde with a polymerization degree of 10 in an amount 0.035 times the mass of pre-modified polypropylene, continue stirring and reacting for 2.5 h, adjust the pH to 6 with a 5% hydrochloric acid aqueous solution, and dry at 75 °C for 10 h under vacuum conditions to obtain modified polypropylene;

[0040] (3) Mix modified polypropylene, modified cellulose, and xylene evenly at a mass ratio of 1:0.07:9. Stir at 130 °C and 55 r / min for 11 min, cool down to 75 °C, and continue stirring for 17 min. Under vacuum conditions, dry at 75 °C for 13 h, and then extrude and pelletize in a screw extruder. Set the temperature of the screw extruder to 185 °C and the screw speed to 90 r / min to obtain a thermoplastic material.

[0041] Example 3:

[0042] A preparation method of a thermoplastic material, the preparation method of the thermoplastic material comprising the following preparation steps:

[0043] (1) Mix cellulose, lithium chloride anhydrous, and N,N-dimethylformamide evenly at a mass ratio of 1:0.3:28. Stir at 80 °C and 300 r / min for 20 min, then cool down to 50 °C. Add 4-isocyanato-2,2,6,6-tetramethyl-1-piperidinyloxy which is 1.4 times the mass of the fiber, and dibutyltin dilaurate which is 0.05 times the mass of the cellulose. Continue to stir and react for 1 h. Under vacuum conditions, dry at 50 °C for 6 h to obtain pre-modified cellulose. Mix the pre-modified fiber, bis(2-chloroethyl) vinylphosphonate, benzoyl peroxide, and toluene evenly at a mass ratio of 1:3:0.05:24. Under a nitrogen atmosphere, stir and react at 85 °C and 300 r / min for 3 h. Under vacuum conditions, dry at 60 °C for 7 h to obtain modified cellulose;

[0044] (2) Mix imidazole, sodium hydroxide, and acetonitrile evenly at a mass ratio of 1:0.12:16. Stir at 30 °C and 300 r / min for 10 min under argon protection. Add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane which is equimolar to imidazole, then raise the temperature to 65 °C and continue to stir and react for 5 h. Under vacuum conditions, dry at 70 °C for 8 h to obtain a siloxane imidazole monomer. Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol evenly at a mass ratio of 1:12. Stir at 52 °C and 300 r / min for 10 min under nitrogen protection. Add 1-amino-5-hexene which is equimolar to 4-hydroxy-1,8-naphthalic anhydride, then raise the temperature to 76 °C and continue to stir and react for 10 h. Cool to room temperature, add deionized water which is 2.2 times the volume of absolute ethanol, let it stand for 2 h, filter, and under vacuum conditions, dry at 60 °C for 8 h to obtain a naphthalimide monomer. Place polypropylene in a mixer and plasticize at 180 °C and 60 r / min for 6 min. Add a siloxane imidazole monomer which is 0.04 times the mass of the polypropylene, add a naphthalimide monomer which is 0.03 times the mass of the polypropylene, continue to plasticize for 4 min, add dicumyl peroxide which is 0.0005 times the mass of the polypropylene, continue to plasticize for 10 min, and cool to room temperature to obtain pre-modified polypropylene. Mix the pre-modified polypropylene, magnesium chloride, and xylene evenly at a mass ratio of 1:0.003:11. Stir at 132 °C and 60 r / min for 10 min, then cool down to 92 °C. Add trimethylamine which is 0.002 times the mass of the pre-modified polypropylene, continue to stir for 8 min, add paraformaldehyde with a polymerization degree of 12 which is 0.04 times the mass of the pre-modified polypropylene, continue to stir and react for 2 h. Adjust the pH to 6.5 with a 5% hydrochloric acid aqueous solution. Under vacuum conditions, dry at 80 °C for 9 h to obtain modified polypropylene;

[0045] (3) Mix the modified polypropylene, modified cellulose, and xylene evenly at a mass ratio of 1:0.08:10, stir at 132 °C and 60 r / min for 10 min, cool down to 80 °C, continue stirring for 16 min, dry at 80 °C for 12 h under vacuum conditions, and then place it in a screw extruder to extrude and pelletize. Set the temperature of the screw extruder to 190 °C and the screw speed to 100 r / min to obtain the thermoplastic material.

[0046] Comparative Example 1:

[0047] The preparation method of the thermoplastic material in Comparative Example 1 is different from that in Example 2 in that step (1) is not carried out, and step (3) is modified as follows: Mix the modified polypropylene, cellulose, and xylene evenly at a mass ratio of 1:0.07:9, stir at 130 °C and 55 r / min for 11 min, cool down to 75 °C, continue stirring for 17 min, dry at 75 °C for 13 h under vacuum conditions, and then place it in a screw extruder to extrude and pelletize. Set the temperature of the screw extruder to 185 °C and the screw speed to 90 r / min to obtain the thermoplastic material. The remaining steps are the same as those in Example 2.

[0048] Comparative Example 2:

[0049] The preparation method of the thermoplastic material in Comparative Example 2 is different from that in Example 2 in step (2). Modify step (2) as follows: Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol evenly at a mass ratio of 1:11, stir at 50 °C and 250 r / min for 15 min under nitrogen protection, add 1-amino-5-hexene in an equimolar amount of 4-hydroxy-1,8-naphthalic anhydride, raise the temperature to 75 °C, continue stirring and reacting for 11 h, cool to room temperature, add deionized water 2.1 times the volume of absolute ethanol, let it stand for 1.5 h, filter, dry at 55 °C for 9 h under vacuum conditions to obtain the naphthalimide monomer; place the polypropylene in a kneader, plasticize at 179 °C and 55 r / min for 7 min, add the naphthalimide monomer 0.025 times the mass of the polypropylene, continue plasticizing for 5 min, add dicumyl peroxide 0.0004 times the mass of the polypropylene, continue plasticizing for 11 min, cool to room temperature to obtain the pre-modified polypropylene; mix the pre-modified polypropylene, magnesium chloride, and xylene evenly at a mass ratio of 1:0.0025:10, stir at 130 °C and 55 r / min for 11 min, cool down to 91 °C, add trimethylamine 0.0015 times the mass of the pre-modified polypropylene, continue stirring for 9 min, add paraformaldehyde with a polymerization degree of 10 0.035 times the mass of the pre-modified polypropylene, continue stirring and reacting for 2.5 h, adjust the pH to 6 with a 5% hydrochloric acid aqueous solution, and dry at 75 °C for 10 h under vacuum conditions to obtain the modified polypropylene. The remaining steps are the same as those in Example 2.

[0050] Comparative Example 3:

[0051] The preparation method of the thermoplastic material of Comparative Example 3 is only different from that of Example 2 in step (2). Step (2) is modified as follows: Imidazole, sodium hydroxide, and acetonitrile are mixed evenly at a mass ratio of 1:0.11:15. Under argon protection, stir at 20 °C and 250 r / min for 15 min. Add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane in an equimolar amount of imidazole, heat up to 60 °C, and continue stirring and reacting for 5.5 h. Under vacuum conditions, dry at 65 °C for 9 h to obtain a siloxane imidazole monomer; Place polypropylene in an internal mixer, plastify at 179 °C and 55 r / min for 7 min, add a siloxane imidazole monomer that is 0.035 times the mass of polypropylene, continue plastifying for 5 min, add diisopropylbenzene peroxide that is 0.0004 times the mass of polypropylene, continue plastifying for 11 min, and cool to room temperature to obtain pre-modified polypropylene; Mix the pre-modified polypropylene, magnesium chloride, and xylene evenly at a mass ratio of 1:0.0025:10, stir at 130 °C and 55 r / min for 11 min, cool down to 91 °C, add trimethylamine that is 0.0015 times the mass of the pre-modified polypropylene, continue stirring for 9 min, add paraformaldehyde with a polymerization degree of 10 that is 0.035 times the mass of the pre-modified polypropylene, continue stirring and reacting for 2.5 h, adjust the pH to 6 with a 5% hydrochloric acid aqueous solution, and dry at 75 °C for 10 h under vacuum conditions to obtain modified polypropylene. The remaining steps are the same as those in Example 2.

[0052] Comparative Example 4:

[0053] The preparation method of the thermoplastic material in Comparative Example 4 is only different from that in Example 2 in step (2). Modify step (2) as follows: Mix imidazole, sodium hydroxide, and acetonitrile evenly at a mass ratio of 1:0.11:15. Under argon protection, stir at 20 °C and 250 r / min for 15 min. Add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane in an equimolar amount of imidazole, heat up to 60 °C, and continue stirring and reacting for 5.5 h. Under vacuum conditions, dry at 65 °C for 9 h to obtain a siloxane imidazole monomer; Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol evenly at a mass ratio of 1:11. Under nitrogen protection, stir at 50 °C and 250 r / min for 15 min. Add 1-amino-5-hexene in an equimolar amount of 4-hydroxy-1,8-naphthalic anhydride, heat up to 75 °C, and continue stirring and reacting for 11 h. Cool to room temperature, add deionized water 2.1 times the volume of absolute ethanol, let stand for 1.5 h, filter, and dry at 55 °C for 9 h under vacuum conditions to obtain a naphthalimide monomer; Place polypropylene in a mixer and knead at 179 °C and 55 r / min for 7 min. Add a siloxane imidazole monomer 0.035 times the mass of polypropylene, add a naphthalimide monomer 0.025 times the mass of polypropylene, continue kneading for 5 min, add diisopropylbenzene peroxide 0.0004 times the mass of polypropylene, continue kneading for 11 min, and cool to room temperature to obtain modified polypropylene. The remaining steps are the same as in Example 2.

[0054] Test Example 1

[0055] Test of Flame Retardancy Performance

[0056] Test method: Prepare standard specimens from the examples and comparative examples according to GB / T2406.2, and test the limiting oxygen index of the standard specimens. The results are shown in Table 1.

[0057] Table 1

[0058] Limiting Oxygen Index (%) Limiting Oxygen Index (%) Example 1 30.76 Comparative Example 1 25.31 Example 2 31.04 Comparative Example 2 26.48 Example 3 30.85 Comparative Example 3 30.37 Comparative Example 4 30.49

[0059] From the comparison of the experimental data of Examples 1-3 and Comparative Examples 1-4 in Table 1, it can be found that the thermoplastic material prepared by the present invention has good flame retardancy performance.

[0060] By comparison, the limiting oxygen index of Examples 1-3 is greater than that of Comparative Example 1, indicating that pre-modified cellulose is prepared by reacting cellulose with 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy, and piperidine-based nitroxide radicals are introduced onto the pre-modified cellulose; the double bond on vinylphosphonic acid bis(2-chloroethyl ester) reacts with the piperidine-based nitroxide radicals introduced onto the pre-modified cellulose to obtain modified cellulose; phosphorus elements are introduced onto the modified cellulose; the introduction of phosphorus elements can improve the flame retardancy performance of the thermoplastic material.

[0061] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 2, indicating that the siloxane imidazole monomer is grafted onto the side chains of polypropylene by the melt grafting method to obtain pre-modified polypropylene; an Si-O-Si bond is introduced into the side chains of the pre-modified polypropylene molecules, and the introduction of the Si-O-Si bond can improve the flame retardancy of thermoplastic materials.

[0062] Test Example 2

[0063] Testing of mechanical properties, anti-aging properties and thermoreversible self-healing properties

[0064] Test method: According to GB / T1040-92, the examples and comparative examples are prepared into standard specimens, and their tensile strength M is tested; the standard specimens are irradiated with a xenon arc lamp for 14 days, and their tensile strength N is tested; a crack with a depth of 2 mm and a length of 20 mm is made in the middle of the standard specimen, kept at 140 °C for 2 h, and left standing at room temperature for 10 h to obtain the repaired specimen, and its tensile strength Q is tested; the change rate of tensile strength of the examples and comparative examples before and after ultraviolet aging treatment is calculated, and the change rate of tensile strength = (M - N) / M × 100%; the self-healing rate of the examples and comparative examples before and after repair is calculated, and the self-healing rate = (Q / M) × 100%. The results are shown in Table 2.

[0065] Table 2

[0066]

[0067]

[0068] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the thermoplastic material prepared by the present invention has good mechanical properties, anti-aging properties and thermoreversible self-healing properties.

[0069] By comparison, the tensile strength of Examples 1 to 3 is greater than that of Comparative Example 1, indicating that pre-modified cellulose is prepared by reacting cellulose with 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy, and piperidine nitroxide radicals are introduced onto the pre-modified cellulose; the double bond on vinylphosphonic acid bis(2-chloroethyl ester) reacts with the piperidine nitroxide radicals introduced onto the pre-modified cellulose to obtain modified cellulose; chlorine atoms are introduced onto the modified cellulose, and the chlorine atoms can react with the alkyl imidazoles introduced onto the side chains of the modified polypropylene molecules to form imidazolium salts, forming a crosslinked network structure, inhibiting the relative slippage between the polypropylene molecular chains, and improving the mechanical properties of the thermoplastic material.

[0070] By comparison, the tensile strengths of Examples 1 to 3 are greater than that of Comparative Example 2, indicating that a siloxane imidazole monomer is prepared by reacting imidazole with 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane; the carbon-carbon double bond on the siloxane imidazole monomer is grafted onto the side chain of polypropylene by melt grafting to obtain pre-modified polypropylene; an alkyl imidazole is introduced onto the side chain of the pre-modified polypropylene molecule, and the alkyl imidazole can react with the chlorine atoms introduced onto the modified cellulose to generate an imidazolium salt, forming a crosslinked network structure, inhibiting the relative slippage between the polypropylene molecular chains, and improving the mechanical properties of the thermoplastic material.

[0071] By comparison, the change rates of the tensile strengths of Examples 1 to 3 are less than those of Comparative Examples 3 to 4, indicating that a naphthalimide monomer is prepared by reacting 4-hydroxy-1,8-naphthalic anhydride with 1-amino-5-hexene; the carbon-carbon double bond on the naphthalimide monomer is grafted onto the side chain of polypropylene by melt grafting to obtain pre-modified polypropylene; a 4-hydroxy-1,8-naphthalimide structure is introduced onto the side chain of the pre-modified polypropylene molecule; the 4-hydroxy-1,8-naphthalimide on the pre-modified polypropylene is reacted with paraformaldehyde to obtain modified polypropylene, and an o-hydroxy naphthalimide formaldehyde structure is formed on the modified polypropylene. The o-hydroxy naphthalimide formaldehyde structure can undergo a ring-opening and ring-closing reaction under the alternating action of ultraviolet light and visible light, thereby absorbing ultraviolet light and releasing the ultraviolet light in a harmless form, improving the anti-aging performance of the thermoplastic material.

[0072] By comparison, the self-healing rate of Examples 1 to 3 is greater than that of Comparative Example 1, indicating that pre-modified cellulose is prepared by reacting cellulose with 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy, and a piperidine nitroxide radical is introduced onto the pre-modified cellulose; the piperidine nitroxide radical introduced onto the pre-modified cellulose reacts with the double bond on bis(2-chloroethyl) vinylphosphonate to obtain modified cellulose; an alkoxyamine bond is formed on the modified cellulose, and at the same time, chlorine atoms are introduced; the chlorine atoms can react with the alkyl imidazole introduced onto the side chain of the modified polypropylene molecule to generate an imidazolium salt, forming a crosslinked network structure. During the crosslinking process, an alkoxyamine bond is also introduced between the modified cellulose and the modified polypropylene. The alkoxyamine bond is a thermally reversible chemical bond that breaks at high temperature to generate nitroxide radicals and carbon radicals, and re-bonds at low temperature to form a new alkoxyamine bond, thereby endowing the thermoplastic material with thermally reversible self-healing performance.

[0073] By comparison, the self-healing rates of Examples 1 to 3 are greater than that of Comparative Example 2, indicating that even if the thermoplastic material contains alkoxyamine bonds, if the alkoxyamine bonds do not form a crosslinked structure between the polypropylene molecular chains, the thermoreversible self-healing effect cannot be achieved; in Comparative Example 2, no alkylimidazole was introduced on the side chain of the modified polypropylene, so a crosslinked structure could not be formed with the chlorine atoms on the modified cellulose; as a result, the alkoxyamine bonds connecting the cellulose and the chlorine atoms did not form a crosslinked structure in the thermoplastic material either; therefore, the thermoreversible self-healing performance cannot be exerted.

[0074] Test Example 3

[0075] Testing of antibacterial properties

[0076] Testing method: Cut the samples of the examples and comparative examples into specimens of 10 mm×10 mm, and sterilize them by ultraviolet irradiation for 3 h; activate the Escherichia coli strain and prepare a bacterial suspension with a concentration of 3×10 4 cfu / ml; put the specimens into the bacterial suspension, shake at 250 r / min for 10 min at room temperature, take 1 ml of the bacterial suspension and dilute it 100 times, take 1 ml of the diluted bacterial suspension and inoculate it into the agar medium, culture it at 37°C for 15 h, perform colony counting according to the method in GB / T 15979, and calculate the antibacterial rate. The results are shown in Table 3.

[0077] Table 3

[0078]

[0079]

[0080] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 3, it can be found that the thermoplastic material prepared by the present invention has good antibacterial properties.

[0081] By comparison, the antibacterial rates of Examples 1 to 3 are greater than that of Comparative Example 1, indicating that pre-modified cellulose was prepared by reacting cellulose with 4-isocyanato-2,2,6,6-tetramethyl-1-piperidinyloxy; piperidine nitroxyl radicals were introduced onto the pre-modified cellulose; the double bonds on vinylphosphonic acid bis(2-chloroethyl ester) reacted with the piperidine nitroxyl radicals introduced onto the pre-modified cellulose to prepare modified cellulose; chlorine atoms were introduced onto the modified cellulose; the chlorine atoms can react with the alkylimidazoles introduced on the side chain of the modified polypropylene to form imidazolium salts, and the imidazolium salts have antibacterial properties, which can improve the antibacterial properties of the thermoplastic material.

[0082] By comparison, the antibacterial rates of Examples 1 to 3 are greater than that of Comparative Example 2, indicating that the siloxane imidazole monomer is prepared by reacting imidazole with 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane; the carbon-carbon double bond on the siloxane imidazole monomer is grafted onto the side chain of polypropylene by melt grafting method to obtain pre-modified polypropylene; alkyl imidazole is introduced onto the side chain of the pre-modified polypropylene molecule; the alkyl imidazole can react with the chlorine atoms introduced on the modified cellulose to generate imidazolium salt, and the imidazolium salt has antibacterial properties, which can improve the antibacterial performance of thermoplastic materials.

[0083] The specific embodiments described above further elaborate on the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thermoplastic material, characterized in that, The thermoplastic material is prepared by reacting pre-modified cellulose with bis(2-chloroethyl) vinylphosphonate to obtain modified cellulose; reacting polypropylene with a siloxane imidazole monomer and a naphthalimide monomer to obtain pre-modified polypropylene; reacting the pre-modified polypropylene with paraformaldehyde to obtain modified polypropylene; and mixing the modified polypropylene and the modified cellulose evenly and then extruding and pelletizing them. The pre-modified cellulose is prepared by reacting cellulose with 4-isocyanato-2,2,6,6-tetramethyl-1-piperidinyloxy. The siloxane imidazole monomer is prepared by reacting imidazole with 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane. The naphthalimide monomer is prepared by reacting 4-hydroxy-1,8-naphthalic anhydride with 1-amino-5-hexene.

2. A method for preparing a thermoplastic material, characterized in that, The preparation method of the thermoplastic material comprises the following preparation steps: (1) Mix pre-modified fiber, bis(2-chloroethyl) vinylphosphonate, benzoyl peroxide, and toluene evenly according to a mass ratio of 1:(2 - 3):(0.03 - 0.05):(20 - 24). Under a nitrogen atmosphere, stir and react at 75 - 85 °C and 200 - 300 r / min for 3 - 4 h, and then dry at 50 - 60 °C under vacuum conditions for 7 - 8 h to obtain modified cellulose. (2) Place polypropylene in a mixer and plastify it at 178 - 180 °C and 50 - 60 r / min for 6 - 8 min. Add a siloxane imidazole monomer with a mass 0.03 - 0.04 times that of the polypropylene, add a naphthalimide monomer with a mass 0.02 - 0.03 times that of the polypropylene, and continue to plastify for 4 - 6 min. Then add dicumyl peroxide with a mass 0.0003 - 0.0005 times that of the polypropylene and continue to plastify for 10 - 12 min. Cool to room temperature to obtain pre-modified polypropylene. Mix the pre-modified polypropylene, magnesium chloride, and xylene evenly according to a mass ratio of 1:(0.002 - 0.003):(9 - 11), stir at 128 - 132 °C and 50 - 60 r / min for 10 - 12 min, cool down to 90 - 92 °C, add trimethylamine with a mass 0.001 - 0.002 times that of the pre-modified polypropylene, continue to stir for 8 - 10 min, add paraformaldehyde with a mass 0.03 - 0.04 times that of the pre-modified polypropylene, continue to stir and react for 2 - 3 h, adjust the pH to 5.5 - 6.5 with a 5% hydrochloric acid aqueous solution, and dry at 70 - 80 °C under vacuum conditions for 9 - 11 h to obtain modified polypropylene. (3) Mix the modified polypropylene, the modified cellulose, and xylene evenly according to a mass ratio of 1:(0.06 - 0.08):(8 - 10), stir at 128 - 132 °C and 50 - 60 r / min for 10 - 12 min, cool down to 70 - 80 °C, continue to stir for 16 - 18 min, dry at 70 - 80 °C under vacuum conditions for 12 - 14 h, and then place it in a screw extruder to extrude and pelletize to obtain the thermoplastic material.

3. The preparation method of a thermoplastic material according to claim 2, characterized in that, The preparation method of the pre-modified cellulose in step (1) is as follows: Mix cellulose, anhydrous lithium chloride, and N,N-dimethylformamide in a mass ratio of 1:(0.2 - 0.3):(26 - 28) evenly, stir at 70 - 80 °C and 200 - 300 r / min for 20 - 30 min, cool down to 40 - 50 °C, add 4-isocyanate-2,2,6,6-tetramethyl-1-piperidyloxy which is 1.2 - 1.4 times the mass of the fiber, and dibutyltin dilaurate which is 0.03 - 0.05 times the mass of the cellulose, continue to stir and react for 1 - 2 h, and dry at 40 - 50 °C under vacuum conditions for 6 - 7 h to obtain the pre-modified cellulose.

4. The preparation method of a thermoplastic material according to claim 3, characterized in that, The molecular weight of the cellulose is 20,000.

5. The preparation method of a thermoplastic material according to claim 2, wherein, The preparation method of the siloxane imidazole monomer in step (2) is as follows: Mix imidazole, sodium hydroxide, and acetonitrile in a mass ratio of 1:(0.1 - 0.12):(14 - 16) evenly, stir at 10 - 30 °C and 200 - 300 r / min for 10 - 20 min under argon protection, add 1-vinyl-3-chloromethyl-1,1,3,3-tetramethyldisiloxane with an equimolar amount of imidazole, raise the temperature to 55 - 65 °C, continue to stir and react for 5 - 6 h, and dry at 60 - 70 °C under vacuum conditions for 8 - 10 h to obtain the siloxane imidazole monomer.

6. The preparation method of a thermoplastic material according to claim 2, characterized in that, The preparation method of the naphthalimide monomer in step (2) is as follows: Mix 4-hydroxy-1,8-naphthalic anhydride and absolute ethanol in a mass ratio of 1:(10 - 12) evenly, stir at 48 - 52 °C and 200 - 300 r / min for 10 - 20 min under nitrogen protection, add 1-amino-5-hexene with an equimolar amount of 4-hydroxy-1,8-naphthalic anhydride, raise the temperature to 74 - 76 °C, continue to stir and react for 10 - 12 h, cool to room temperature, add deionized water which is 2 - 2.2 times the volume of absolute ethanol, let it stand for 1 - 2 h, filter, and dry at 50 - 60 °C under vacuum conditions for 8 - 10 h to obtain the naphthalimide monomer.

7. The preparation method of a thermoplastic material according to claim 2, characterized in that, The model of the polypropylene in step (2) is K8303.

8. The preparation method of a thermoplastic material according to claim 2, characterized in that, The degree of polymerization of the paraformaldehyde in step (2) is 8 - 12.

9. The preparation method of a thermoplastic material according to claim 2, characterized in that, The process parameters of the extrusion granulation in step (3) are: Set the temperature of the screw extruder to 180 - 190 °C and the screw speed to 80 - 100 r / min.

10. Application of a thermoplastic material prepared by the preparation method of the thermoplastic material according to any one of claims 2 - 9 in automotive interiors.

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