Graft modification method of polypropylene and graft modified polypropylene

Abstract

The invention discloses a graft modification method of polypropylene and graft modified polypropylene, and belongs to the technical field of high-molecular compounds, and the graft modification method comprises the following steps: mixing a powdery polypropylene monomer and an organic solvent according to a mass ratio of 0.1-2: 10 to obtain a reaction system, removing oxygen in the reaction system, heating to 20-80 DEG C, introducing inert gas, and reacting for 1-2 hours at the temperature of 20-80 DEG C; the preparation method comprises the following steps: sequentially adding a hydrogen atom transfer initiator accounting for 0.1-15% of the mass of a polypropylene monomer and a functional monomer accounting for 0.1-25% of the mass of the polypropylene monomer into a reaction system, uniformly mixing, gradually introducing oxygen accounting for 1-2 times of the molar mass of the initiator within 1-3 hours, carrying out a solvent grafting reaction for 6-24 hours, and carrying out washing, centrifugal separation and drying on a product after the reaction is finished, so as to obtain the high-strength polypropylene material. The modified grafted polypropylene is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer compounds, and particularly relates to a graft modification method of polypropylene and graft modified polypropylene. Background Art

[0002] Polypropylene (PP), one of the world's most produced general-purpose plastics, boasts key advantages such as high specific strength, excellent chemical resistance, good processing fluidity, and significant cost-effectiveness. These attributes make it a preferred material for packaging films, automotive parts (bumpers, interior trims), appliance housings, medical devices (disposable syringes, infusion bags), and electronic insulation.

[0003] However, its non-polarity and low reactivity limit its application in functional composites. Traditional grafting modification methods, such as melt grafting or solid-phase grafting, typically require high temperatures, high pressures, or strong oxidizing conditions, which can easily lead to degradation of the PP backbone, uneven grafting, or increased by-products. In addition, many methods rely on interfacial agents to improve compatibility, which not only increases process complexity but may also affect the performance stability of the final product.

[0004] Therefore, developing a modification technology with mild reaction conditions, controllable grafting process and no need for additional interface agents is of great significance to expanding the high-end applications of PP. Summary of the Invention

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for grafting modification of polypropylene.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0008] A powdered polypropylene monomer and an organic solvent are mixed in a mass ratio of 0.1 to 2:10 to obtain a reaction system. After removing oxygen from the reaction system, the temperature is raised to 20 to 80° C. and an inert gas is introduced. A hydrogen atom transfer initiator in an amount of 0.1% to 15% by mass relative to the polypropylene monomer and a functional monomer in an amount of 0.1% to 25% by mass relative to the polypropylene monomer are sequentially added to the reaction system. After uniform mixing, oxygen in an amount of 1 to 2 times the molar mass of the initiator is gradually introduced within 1 to 3 hours to carry out a solvent grafting reaction for 6 to 24 hours. After the reaction is completed, the product is washed, centrifuged, and dried to obtain a modified grafted polypropylene.

[0009] The functional monomers include one or more of styrene monomers, maleic anhydride monomers, and 4-propyleneoxy-2-hydroxybenzophenone monomers.

[0010] Preferably, the powdered polypropylene monomer and the organic solvent are mixed in a mass ratio of 0.5 to 1.6:10 to obtain the reaction system; more preferably, the mass ratio is 0.8 to 1:10;

[0011] Preferably, after removing oxygen from the reaction system, the temperature is raised to 20-60° C. and an inert gas is introduced;

[0012] Preferably, 1% to 10% of the mass of the hydrogen atom transfer initiator is added compared to the mass of the polypropylene monomer; more preferably, 1% to 5% of the mass of the hydrogen atom transfer initiator is added compared to the mass of the polypropylene monomer;

[0013] Preferably, oxygen in an amount 1 to 1.5 times the molar mass of the initiator is gradually introduced within 2 to 3 hours, and the solvent grafting reaction is carried out for 9 to 12 hours.

[0014] As a preferred embodiment of the grafting modification method of polypropylene according to the present invention, the organic solvent includes one or more of aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, and special solvents, wherein the aromatic hydrocarbon solvent includes one or more of xylene, toluene, benzene, ethylbenzene, isopropylbenzene, hexane, 1,2,4-trimethylbenzene, chlorobenzene, and 1,2,4-trichlorobenzene; the aliphatic hydrocarbon solvent includes one or more of n-hexane, n-heptane, cyclohexane, decalin, and tetralin; and the special solvent includes one or more of hexafluoroisopropanol and perfluorooctane.

[0015] As a preferred embodiment of the graft modification method of polypropylene according to the present invention, the hydrogen atom transfer initiator includes one or more of tributyl boron initiators, tri-sec-butyl borane initiators, triethyl boron initiators, triphenyl boron initiators, triisobutyl boron initiators, triisobutyl aluminum initiators, azobisisobutyronitrile initiators, azobisisoheptanenitrile initiators, dimethyl azobisisobutyrate initiators, azobiscyclohexylcarbonitrile initiators, potassium persulfate, and sodium bisulfite.

[0016] Wherein, the tributyl boron initiator has the general structural formula shown in formula (A); Formula (A);

[0017] In formula (A), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 12 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0018] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0019] The tri-sec-butylborane initiator has the general structural formula shown in formula (B); Formula (B);

[0020] In formula (B), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 12 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0021] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0022] The triethyl boron initiator has the general structural formula shown in formula (C); Formula (C);

[0023] In formula (C), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R6 are each independently selected from a substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0024] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0025] The triphenylboron initiator has the general structural formula shown in formula (D); Formula (D);

[0026] In formula (D), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 15 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0027] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0028] The triisobutylaluminum initiator has the general structural formula shown in formula (E); Formula (E);

[0029] In formula (E), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R7 are each independently selected from a substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0030] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0031] The azobisisobutyronitrile initiator has the general structural formula shown in formula (F); Formula (F);

[0032] In formula (F), R1 and R2 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R3-R4 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0033] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0034] The azobisisoheptanenitrile initiator has the general structural formula shown in formula (G); Formula (G);

[0035] In formula (G), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 12 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0036] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0037] The dimethyl azobisisobutyrate initiator has the general structural formula shown in formula (H); Formula (H);

[0038] In formula (H), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R8 are each independently selected from a substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0039] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino;

[0040] The azobiscyclohexylcarbonitrile initiator has the general structural formula shown in formula (J); Formula (J);

[0041] In formula (J), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 10 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0042] Preferably, R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C3 alkyl, and R4-R8 are each independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, H, halogen, hydroxyl, and amino.

[0043] As a preferred embodiment of the graft modification method of polypropylene of the present invention, the styrene monomer is a styrene compound polymerized by free radicals, and is selected from one of the structural formulas shown in any one of formulas (I) to (III); Formula (I); Formula (II); Formula (III);

[0044] In formula (I), R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R4-R8 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 One of amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0045] In formula (II), R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R4-R 10 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups;

[0046] In formula (III), R1', R2', and R3' are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R4'-R 10 ' are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

[0047] As a preferred embodiment of the graft modification method of polypropylene of the present invention, the maleic anhydride monomer is a maleic anhydride compound polymerized by free radicals, and the structural formula is shown in formula (IV); Formula (IV);

[0048] In formula (IV), R1-R2 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

[0049] As a preferred embodiment of the graft modification method of polypropylene of the present invention, the 4-propyleneoxy-2-hydroxybenzophenone monomer is a 4-propyleneoxy-2-hydroxybenzophenone compound polymerized by free radicals, and the structural formula is shown in formula (V); Formula (V);

[0050] In formula (V), n is in the range of 1 to 12, R1 and R2 are independently selected from H, substituted or unsubstituted C1-C6 alkyl, R4-R 11 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

[0051] Beneficial effects of the present invention: a. This invention achieves efficient and controllable grafting under mild conditions (normal pressure) by optimizing the reaction system. Furthermore, by adjusting the monomer concentration and reaction kinetics, the length and distribution of the grafted chains can be controlled, and uniformly modified PP materials can be obtained without the introduction of an interfacial agent. b. The hydrogen atom transfer initiator (HAT) of this invention can react with trace amounts of oxygen or monomers at room temperature or even low temperatures (0-50°C) to produce controllable concentrations of free radicals, avoiding the high temperatures (usually >100°C) or strong oxidizing environments required by peroxide initiators, thereby reducing the risk of PP backbone degradation. c. The hydrogen atom transfer initiator of the present invention can form a homogeneous system with PP in organic solvents (such as toluene, benzene, and xylene), resulting in low monomer diffusion resistance, more uniform distribution of grafting points, and no reliance on interfacial agents. Solution grafting directly acts on the PP molecular chain, eliminating the need for additional additives and resulting in a purer product. d. The grafting modification method of the present invention is selective grafting. The free radicals triggered by the hydrogen atom transfer initiator preferentially attack the tertiary hydrocarbons of PP. The generation rate and activity of the free radicals are precisely controlled in the solution, avoiding the chain breakage or cross-linking problems caused by the violent reaction in traditional methods. The grafting sites are more controllable and the by-products are reduced.

[0052] Another object of the present invention is to provide a graft-modified polypropylene obtained by a graft-modified polypropylene method.

[0053] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0054] The graft-modified polypropylene has a structural formula shown in either Formula VI or Formula VII; Formula (VI); Formula (VII); In formula (VI), R' is any one of a structural unit derived from copolymerized polypropylene, a structural unit derived from a styrene monomer, a structural unit derived from a maleic anhydride monomer, and a structural unit derived from a 4-propyleneoxy-2-hydroxybenzophenone monomer; In formula (VII), R1', R2', and R1' are independently any one of a structural unit derived from copolymerized polypropylene, a structural unit derived from a styrene monomer, a structural unit derived from a maleic anhydride monomer, and a structural unit derived from a 4-propyleneoxy-2-hydroxybenzophenone monomer.

[0055] As a preferred embodiment of the graft modified polypropylene of the present invention, the copolymerized polypropylene is a propylene copolymer containing ethylene or a higher α-olefin or a mixture thereof;

[0056] The comonomer of the copolymerized polypropylene is selected from at least one of C2-C8 α-olefins other than propylene; the C2-C8 α-olefins other than propylene include at least one of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene.

[0057] It should be noted that the "structural unit" described in the present invention means that it is a part of the grafted modified polypropylene, and its form is not limited. Specifically, the "structural unit derived from copolymerized polypropylene" refers to the product formed by copolymerized polypropylene, which includes both the "group" form and the "polymer" form. The "structural unit derived from styrene monomers" refers to the product formed by styrene monomers, which includes both the "group" form, the "monomer" form, and the "polymer" form. The "structural unit derived from maleic anhydride monomers" refers to the product formed by maleic anhydride monomers, which includes both the "group" form, the "monomer" form, and the "polymer" form. The "structural unit derived from 4-propyleneoxy-2-hydroxybenzophenone monomers" refers to the product formed by maleic anhydride monomers, which includes both the "group" form, the "monomer" form, and the "polymer" form. The "structural unit" can be a repeating unit or a non-repeating independent unit.

[0058] In the present invention, the meaning of "comonomer" in copolymerized polypropylene is well known to those skilled in the art, and refers to a monomer copolymerized with propylene.

[0059] The grafting reaction of the present invention is a free radical polymerization reaction. Therefore, the "grafted state" refers to the state in which a reactant forms a connection with another reactant after free radical polymerization. The connection includes both direct connection and indirect connection.

[0060] As a preferred embodiment of the graft-modified polypropylene of the present invention, the content of the structural units derived from styrene monomers and in a grafted state in the graft-modified polypropylene is 0.1% to 20%, preferably 1% to 10%, and more preferably 5% to 10%, calculated as a percentage by mass of the graft-modified polypropylene;

[0061] The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene is 0.1% to 15%, preferably 1% to 10%, and more preferably 5% to 10%;

[0062] The content of the structural units derived from 4-propyleneoxy-2-hydroxybenzophenone monomers and in a grafted state in the grafted modified polypropylene is 0.1% to 25%, preferably 1% to 10%, and more preferably 5% to 10%.

[0063] The term "graft-modified polypropylene" of the present invention includes both the product (crude product) directly obtained by grafting copolymerized polypropylene and one or more of styrene monomers, maleic anhydride monomers and 4-propyleneoxy-2-hydroxybenzophenone monomers, and also includes the pure graft-modified polypropylene obtained by further purification of the product.

[0064] The copolymerized polypropylene of the present invention may be a heterophasic propylene copolymer. The heterophasic propylene copolymer may contain a propylene homopolymer or a propylene random copolymer matrix component (1), and another propylene copolymer component (2) dispersed therein. In a propylene random copolymer, the comonomer is randomly distributed on the main chain of the propylene polymer. Preferably, the copolymerized polypropylene of the present invention is a heterophasic propylene copolymer prepared in situ in a reactor by an existing process.

[0065] According to a preferred embodiment, the heterophasic propylene copolymer comprises a propylene homopolymer matrix or a random copolymer matrix (1) and a propylene copolymer component (2) containing one or more ethylene or higher α-olefin comonomers dispersed therein. The heterophasic propylene copolymer may have an island-in-the-sea structure or a bicontinuous structure.

[0066] Two types of heterophasic propylene copolymers are known in the art: heterophasic propylene copolymers containing a propylene random copolymer as a matrix phase or heterophasic propylene copolymers containing a propylene homopolymer as a matrix phase. The random copolymer matrix (1) is a copolymer in which the comonomers are partially randomly distributed along the polymer chain, in other words, consisting of an alternating sequence of two monomer units of random length (including single molecules). Preferably, the comonomer in the matrix (1) is selected from hexene or butene. Particularly preferably, the comonomer in the matrix (1) is ethylene.

[0067] Preferably, the propylene copolymer (2) dispersed in the homopolymer or copolymer matrix (1) of the heterophasic propylene copolymer is substantially amorphous. The term "substantially amorphous" herein means that the propylene copolymer (2) has a lower crystallinity than the homopolymer or copolymer matrix (1).

[0068] As a preferred embodiment of the graft-modified polypropylene of the present invention, the graft-modified polypropylene has at least one of the following characteristics: (a) Oxidation induction time ≥ 45 min at 220°C; (b) flexural modulus > 1000 MPa; (c) Melting temperature T m >165℃; (d) Ultraviolet radiation transmittance <4%; (e) Tensile strain at break at 23°C (50 mm / min) ≥ 500%; (f) Peel strength >260 N / cm at 23°C, peel strength >110 N / cm at 80°C, peel strength >65 N / cm at 110°C, peel strength >35 N / cm at 140°C; (g) Low temperature impact strength>40KJ / M².

[0069] Furthermore, the graft-modified polypropylene of the present invention also has at least one of the following characteristics: (h) a comonomer content of 0.5 to 40 mol%, preferably 0.5 to 30 mol%, preferably 4 to 25 wt%, more preferably 4 to 22 wt%; (i) a xylene soluble content of 2 to 80 wt%, preferably 18 to 75 wt%, more preferably 30 to 70 wt%, and even more preferably 30 to 67 wt%; (j) the comonomer content in the soluble matter is 10 to 70 wt%, preferably 10 to 50 wt%, more preferably 20 to 35 wt%; (k) The intrinsic viscosity ratio of soluble matter to polypropylene is 0.3 to 5; (l) tensile strength> 5MPa; (m) Dielectric constant measured at 50 Hz and 20°C: 3.0; (n) The dielectric loss factor measured at 50 Hz and 20°C is 3.010-4; (o) Impact resistance index 2~50kJ / m 2 ; (p) melt strength 10~50cN; (q) weight average molecular weight is 20×10 4 ~60×10 4 g / mo1; (r) Elongation at break > 200%.

[0070] It should be noted that, with high T m The basic polypropylene has satisfactory impact strength and flexibility at both low and high temperatures. In addition, when using m When the base polypropylene is used, the aromatic olefin grafted modified polypropylene of the present invention has the advantage of being able to withstand higher working temperatures.

[0071] Beneficial effects of the present invention: (1) The graft-modified polypropylene prepared by the present invention is grafted with multifunctional monomers at multiple sites simultaneously, thereby achieving high performance of polypropylene, such as low dielectric loss, high adhesion, impact resistance, aging resistance, functional coating, high melt strength, etc.; (2) When maleic anhydride monomers are selected to graft-modify polypropylene in the present invention, the polarity of PP can be significantly improved by introducing carboxylic anhydride groups (-CO-O-CO-), thereby improving its compatibility. Secondly, the anhydride groups can react chemically with materials containing amino groups or hydroxyl groups (such as reacting with the amino groups of nylon) to form strong interfacial chemical bonds, thereby greatly improving the mechanical properties of the composite material (such as tensile strength and impact strength). In addition, the grafting of maleic anhydride onto polypropylene can delay the thermal degradation of polypropylene and increase its heat deformation temperature. (3) When the present invention selects styrene monomers to graft-modify polypropylene, the styrene chain segments can reduce the melt viscosity of the modified polypropylene, increase fluidity, and improve processing performance; secondly, the styrene monomer modified polypropylene can improve impact resistance by forming a microphase separation structure, and the rigid benzene ring of styrene can compensate for the flexibility of the modified polypropylene, thereby improving the modulus and dimensional stability; finally, after the introduction of styrene, new functions can be imparted to the modified polypropylene through subsequent reactions (such as sulfonation and bromination), thereby improving the flame retardancy and ion exchange capacity of the modified polypropylene; (4) When the present invention selects 4-propyleneoxy-2-hydroxybenzophenone monomers to graft-modify polypropylene, the 2-hydroxybenzophenone group of AHBP is a classic ultraviolet absorber (UVA) that can effectively absorb ultraviolet rays from 290 to 400 nm, so the grafted modified polypropylene has excellent ultraviolet absorption and light stability; secondly, AHBP is chemically bonded to the polymer chain, avoiding migration, volatilization or precipitation problems, and achieving permanent anti-ultraviolet performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0073] Figure 1 This is a gel permeation chromatography (GPC) chart of the grafted modified polypropylene obtained in Example 1 of the present invention.

[0074] Figure 2 This is the infrared spectrum of the grafted modified polypropylene obtained in Example 1 of the present invention.

[0075] Figure 3 This is the gel permeation chromatography (GPC) chart of the grafted modified polypropylene obtained in Example 2 of the present invention.

[0076] Figure 4 This is the infrared spectrum of the grafted modified polypropylene obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0077] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0078] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0079] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0080] Unless otherwise specified, the raw materials used in the present invention are commonly available in the market.

[0081] The particle size of the raw polypropylene powder of the present invention is 0.1-1 mm, and the powder can be prepared by using a Ziegler-Natta catalyst through reactor particle technology without any treatment such as melt granulation and addition of antioxidants.

[0082] Example 1

[0083] This embodiment provides a polypropylene modification method, specifically:

[0084] 1) Mixing polypropylene powder and toluene to obtain a reaction system, wherein the mass ratio of polypropylene powder to organic solvent is 0.1:1, evacuating the system with a vacuum pump and replacing the system with nitrogen four times to remove oxygen from the reaction system;

[0085] 2) The reaction system was heated to 40°C, and the initiator tributylboron (the general structure is shown in formula (A), where R1 is CH3, R2-R 12 is CH2CH3) and maleic anhydride monomer (the general structural formula is shown in formula (IV), R1 is CH3, R2 is CH2COOH) are added to the reaction system and mixed evenly with polypropylene A, oxygen is gradually introduced within 3 hours, and the reaction is carried out for a total of 12 hours to carry out a solution grafting reaction, wherein the amount of initiator is 5% of polypropylene A, the amount of maleic anhydride monomer is 10% of polypropylene A, and the amount of oxygen introduced is 1 times the molar amount of the initiator;

[0086] 3) After the solution grafting reaction is completed, the product is washed with acetone three times, centrifuged at 10,000 rpm / min, and dried at 60° C. for 2 hours to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 3% structural units derived from maleic anhydride monomers and in a grafted state.

[0087] The grafting rate of the graft-modified polypropylene of this embodiment was determined to be 1.2%, the grafting efficiency was 12%, the flexural modulus was 1200 MPa, the melting temperature was 165°C, and the gel permeation chromatography (GPC) diagram thereof was shown in FIG. Figure 1 As shown, the horizontal axis of the GPC graph represents the logarithmic molecular weight (LogM), and the vertical axis represents the differential of the mass fraction to the logarithmic molecular weight, which represents the mass fraction within the unit logarithmic molecular weight range at the point M corresponding to a certain molecular weight logM. In the same graph, for peaks with similar molecular weight distribution widths, the peak height can qualitatively reflect the local mass concentration of the polymer near the molecular weight. The higher the peak, the greater the mass distribution density of the polymer in the molecular weight range. Figure 2As shown in the figure, PP represents unmodified polypropylene, and PP-MAH represents modified polypropylene grafted with maleic anhydride. It can be seen from the figure that the GPC of grafted modified polypropylene has not been significantly reduced, indicating that the polypropylene molecular chain has not been depolymerized; in the infrared spectrum, at 1780 cm -1 A new peak appears at , indicating that polypropylene has been successfully modified.

[0088] Example 2 1) Mixing polypropylene powder and toluene to obtain a reaction system, wherein the mass ratio of polypropylene powder to organic solvent is 0.15:1, evacuating the system with a vacuum pump and replacing the system with nitrogen four times to remove oxygen from the reaction system; 2) The reaction system was heated to 25°C, and the initiator tributylboron (the general structure is shown in formula (A), where R1 is CH2NH2, R2-R 12 is CH2CH3) and maleic anhydride monomer (the general structural formula is shown in formula (IV), R1 is CH2CH3, R2 is CH2CH2COOH) are added to the reaction system and mixed evenly with polypropylene A, oxygen is gradually introduced within 2.5 hours, and the reaction is carried out for a total of 12 hours to carry out a solution grafting reaction, wherein the amount of initiator is 5% of the polypropylene A, the amount of maleic anhydride monomer is 15% of the polypropylene A, and the amount of oxygen introduced is 1.5 times the molar amount of the initiator; 3) After the solution grafting reaction is completed, the product is centrifuged three times at 10,000 rpm / min, washed three times with acetone, and dried at 60°C for 2 hours to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 0.9% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0089] The grafting rate of the graft-modified polypropylene of this embodiment was determined to be 0.9%, the grafting efficiency was 6%, the flexural modulus was 1005 MPa, the melting temperature was 166°C, and the gel permeation chromatography (GPC) diagram thereof was shown in FIG. Figure 3 As shown, the horizontal axis of the GPC graph represents the logarithmic molecular weight (LogM), and the vertical axis represents the differential of the mass fraction to the logarithmic molecular weight, which represents the mass fraction within the unit logarithmic molecular weight range at the point M corresponding to a certain molecular weight logM. In the same graph, for peaks with similar molecular weight distribution widths, the peak height can qualitatively reflect the local mass concentration of the polymer near the molecular weight. The higher the peak, the greater the mass distribution density of the polymer in the molecular weight range. Figure 4 As shown in the figure, PP represents unmodified polypropylene, and PP-MAH represents modified polypropylene grafted with maleic anhydride. It can be seen from the figure that the GPC of grafted modified polypropylene has not been significantly reduced, indicating that the polypropylene molecular chain has not been depolymerized; in the infrared spectrum, at 1780 cm -1A new peak appears at , indicating that polypropylene has been successfully modified.

[0090] Example 3 1) Mixing polypropylene powder and toluene to obtain a reaction system, wherein the mass ratio of polypropylene powder to organic solvent is 0.1:1, evacuating the system with a vacuum pump and replacing the system with nitrogen four times to remove oxygen from the reaction system; 2) The reaction system was heated to 80°C, and the initiator tributylboron (the general structure is shown in formula (A), where R1 is CH3, R2-R 12 is CH2CH3) and maleic anhydride monomer (the general structural formula is shown in formula (IV), R1 is H, R2 is CH2CH2COOH) are added to the reaction system and mixed evenly with polypropylene A, oxygen is gradually introduced within 2.5 hours, and the reaction is carried out for a total of 12 hours to carry out a solution grafting reaction, wherein the amount of initiator is 10% of polypropylene A, the amount of maleic anhydride monomer is 10% of polypropylene A, and the amount of oxygen introduced is 1.5 times the molar amount of the initiator; 3) After the solution grafting reaction is completed, the product is centrifuged three times at 6000 rpm / min, washed three times with acetone, and then dried at 60°C for 2 hours to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this embodiment is 0.8%.

[0091] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.8%, the grafting efficiency is 8%, the flexural modulus is 1120 MPa, and the melting temperature is 165°C.

[0092] Example 4 1) Mixing polypropylene powder and toluene to obtain a reaction system, wherein the mass ratio of polypropylene powder to organic solvent is 0.1:1, evacuating the system with a vacuum pump and replacing the system with nitrogen four times to remove oxygen from the reaction system; 2) The reaction system was heated to 50°C, and the initiator tributylboron (the general structure is shown in formula (A), where R1 is CH2COOH, R2-R 12 =CH2CH3) and maleic anhydride monomer (with the general structural formula shown in formula (IV), R1 is CH3, R2 is CH3) are added to the reaction system and uniformly mixed with polypropylene A, and oxygen is gradually introduced within 2.7 hours, and the reaction is carried out for a total of 10 hours to carry out a solution grafting reaction, wherein the amount of initiator is 10% of polypropylene A, the amount of maleic anhydride monomer is 12% of polypropylene A, and the amount of oxygen introduced is twice the molar amount of the initiator; 3) After the solution grafting reaction is completed, the product is centrifuged three times at 6000 rpm / min, washed three times with acetone, and then dried at 60°C for 2 hours to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this embodiment is 0.9%.

[0093] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.9%, the grafting efficiency is 7.5%, the flexural modulus is 1109 MPa, and the melting temperature is 165°C.

[0094] Comparing the grafting effects of the graft-modified polypropylene under the schemes of Examples 1 to 4, the results are shown in Table 1: Table 1 Comparison of properties of graft modified polypropylene products obtained in Examples 1 to 4

[0095] Example 5

[0096] This embodiment differs from Embodiment 1 in that the initiator is changed to triethylboron (with the general structural formula shown in Formula (C), R1 is CH3, and R2-R6 are CH2CH3). The remaining steps and processes are the same as those in Embodiment 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 1.3% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0097] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 1.3%, the grafting efficiency was 13%, the flexural modulus was 1234 MPa, and the melting temperature was 165°C.

[0098] Example 6

[0099] This embodiment differs from Embodiment 1 in that the initiator is changed to triethylboron (with the general structural formula shown in Formula (C), R1 is CH3, and R2-R6 are CH2CH3), and the amount of initiator used is 15% of the polypropylene A. The remaining steps and processes are the same as those in Embodiment 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 3.5% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0100] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 3.5%, the grafting efficiency is 35%, the flexural modulus is 1432 MPa, and the melting temperature is 167°C.

[0101] Example 7

[0102] The difference between this embodiment and embodiment 1 is that the initiator is adjusted to triethylboron (the general structural formula is shown in formula (C), R1 is CH2NH2, R2-R12 The amount of initiator used was 0.1% of the polypropylene A. The remaining steps and processes were the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this embodiment was 0.3%.

[0103] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.3%, the grafting efficiency is 3%, the flexural modulus is 1120 MPa, and the melting temperature is 164°C.

[0104] Example 8

[0105] The difference between this embodiment and embodiment 1 is that the initiator is adjusted to triphenylboron (the general structural formula is shown in formula (D), R1 is CH2NH2, R2-R 15 The remaining steps and processes are the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this embodiment is 1.5%.

[0106] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 1.5%, the grafting efficiency was 15%, the flexural modulus was 1132 MPa, and the melting temperature was 165°C.

[0107] Example 9

[0108] The difference between this embodiment and embodiment 1 is that the initiator is adjusted to triphenylboron (the general structural formula is shown in formula (D), R1 is CH2NH2, R2-R 15 The amount of initiator used was 0.1% of the polypropylene A. The remaining steps and processes were the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this embodiment was 0.6%.

[0109] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.6%, the grafting efficiency is 6%, the flexural modulus is 1098 MPa, and the melting temperature is 166°C.

[0110] Example 10

[0111] The difference between this embodiment and embodiment 1 is that the initiator is adjusted to triphenylboron (the general structural formula is shown in formula (D), R1 is CH2NH2, R2-R 15The amount of initiator used was 15% of that of polypropylene A. The remaining steps and processes were the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this embodiment was 3.1%.

[0112] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 3.1%, the grafting efficiency is 31%, the flexural modulus is 1398 MPa, and the melting temperature is 167°C.

[0113] Example 11

[0114] This embodiment differs from Embodiment 1 in that the initiator is changed to triisobutylboron (with the general structural formula shown in Formula (E), R1 is CH2NH2, and R2-R7 are CH2CH3), and the amount of initiator used is 15% of the polypropylene A. The remaining steps and processes are the same as those in Embodiment 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 3.1% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0115] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 3.1%, the grafting efficiency was 31%, the flexural modulus was 1389 MPa, and the melting temperature was 167°C.

[0116] Example 12

[0117] This embodiment differs from Embodiment 1 in that the initiator is changed to triisobutylboron (with the general structural formula shown in Formula (E), R1 is CH2NH2, and R2-R7 are CH2CH3), and the amount of the initiator used is 0.1% of the polypropylene A. The remaining steps and processes are the same as those in Embodiment 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 0.4% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0118] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.4%, the grafting efficiency is 4%, the flexural modulus is 1089 MPa, and the melting temperature is 165°C.

[0119] Example 13

[0120] This embodiment differs from Embodiment 1 in that the initiator is changed to triisobutylboron (with the general structural formula shown in Formula (E), R1 is CH2NH2, and R2-R7 are CH2CH3), and the amount of initiator used is 6% of the polypropylene A. The remaining steps and processes are the same as those in Embodiment 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 1.4% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0121] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 1.4%, the grafting efficiency was 14%, the flexural modulus was 1135 MPa, and the melting temperature was 165°C.

[0122] Example 14

[0123] This embodiment differs from Embodiment 1 in that the initiator is azobisisobutyronitrile (with a general structural formula as shown in Formula (F), where R1 is CH2NH2 and R2-R4 are CH2CH3), and the amount of the initiator used is 0.1% of the polypropylene A. The remaining steps and processes are the same as those of Embodiment 1 to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment has a structural unit derived from maleic anhydride monomers and a grafted structural unit content of 0.6%.

[0124] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 0.6%, the grafting efficiency was 6%, the flexural modulus was 1125 MPa, and the melting temperature was 164°C.

[0125] Example 15

[0126] This embodiment differs from Example 1 in that the initiator is azobisisobutyronitrile (with the general structural formula shown in Formula (F), where R1 is CH2NH2 and R2-R4 are CH2CH3), and the amount of initiator used is 15% of the polypropylene A. The remaining steps and processes are the same as those in Example 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 2.9% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0127] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 2.9%, the grafting efficiency was 29%, the flexural modulus was 1389 MPa, and the melting temperature was 166°C.

[0128] Example 16

[0129] This embodiment differs from Example 1 in that the initiator is changed to dimethyl azobisisobutyrate (with the general structural formula shown in Formula (H), R1 is CH2NH2, and R2-R4 are CH2CH3), and the amount of the initiator used is 0.1% of the polypropylene A. The remaining steps and processes are the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment has a structural unit derived from maleic anhydride monomers and a grafted structural unit content of 0.5%.

[0130] According to the measurement, the grafting rate of the graft-modified polypropylene of this embodiment is 0.5%, the grafting efficiency is 5%, the flexural modulus is 1097 MPa, and the melting temperature is 165°C.

[0131] Example 17

[0132] This embodiment differs from Example 1 in that the initiator is changed to dimethyl azobisisobutyrate (with the general structural formula shown in Formula (H), R1 is CH2NH2, and R2-R8 are CH2CH3), the amount of initiator used is 15% of the polypropylene A, and the remaining steps and processes are the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment has a structural unit derived from maleic anhydride monomers and a grafted structural unit content of 3.2%.

[0133] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 3.2%, the grafting efficiency is 32%, the flexural modulus is 1396 MPa, and the melting temperature is 167°C.

[0134] Example 18

[0135] This embodiment differs from Example 1 in that the initiator is changed to dimethyl azobisisobutyrate (with the general structural formula shown in Formula (H), R1 is CH2NH2, and R2-R8 are CH2CH3), the amount of initiator used is 15% of the polypropylene A, and the remaining steps and processes are the same as those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment has a structural unit derived from maleic anhydride monomers and a grafted structural unit content of 3.2%.

[0136] According to the measurement, the grafting rate of the graft-modified polypropylene of this embodiment is 3.2%, the grafting efficiency is 32%, the flexural modulus is 1411 MPa, and the melting temperature is 167°C.

[0137] Example 19

[0138] The difference between this embodiment and embodiment 1 is that the initiator is adjusted to tributylboron (the general structural formula is shown in formula (A), R1 is CH2NH2, R2-R 12 A mixed initiator was prepared by mixing triisobutylaluminum (with the general structural formula shown in Formula (E), wherein R1 is CH2CH3) in a mass ratio of 1:1. The remaining steps and processes were the same as those in Example 1 to obtain the graft-modified polypropylene of this example. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the graft-modified polypropylene of this example was 1.5%.

[0139] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 1.5%, the grafting efficiency is 15%, the flexural modulus is 1200 MPa, and the melting temperature is 165°C.

[0140] Example 20

[0141] This embodiment differs from Example 1 in that the amount of the initiator tributyl boron is adjusted to 10% of the polypropylene powder. The remaining steps and processes are the same as those in Example 1, thereby obtaining the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 0.5% structural units derived from maleic anhydride monomers and in a grafted state.

[0142] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.5%, the grafting efficiency is 5%, the flexural modulus is 1079 MPa, and the melting temperature is 165°C.

[0143] Comparative Example 1

[0144] The difference between this comparative example and Example 1 is that the initiator is adjusted to benzoyl peroxide, and the remaining steps and processes are referred to Example 1 to obtain the grafted modified polypropylene of this comparative example. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this comparative example is 0.08%.

[0145] The results show that the grafting rate of the graft-modified polypropylene in this comparative example is 0.08%, the grafting efficiency is 0.8%, the flexural modulus is 1008 MPa, and the melting temperature is 164°C.

[0146] Comparing Example 1 with Examples 5 to 20 and the grafting effect of graft-modified polypropylene under different initiator schemes of Comparative Example 1, the results are shown in Table 2:

[0147] Table 2 Grafting effect of grafted modified polypropylene under different initiator conditions

[0148] As can be seen from Table 2, the grafting effect of the hydrogen atom transfer initiator (HAT) of the present invention has significant advantages over other initiators. This is because HAT can react with trace amounts of oxygen or monomers at room temperature or even low temperatures (0-50°C) to produce free radicals of controllable concentrations, avoiding the high temperatures (usually >100°C) or strong oxidizing environments required by peroxide initiators, thereby reducing the risk of PP main chain degradation.

[0149] Example 21

[0150] This embodiment differs from Embodiment 1 in that the maleic anhydride monomer is replaced with a styrene monomer, wherein R1 is CH3 and R2-R8 are CH2CH3. The remaining steps and processes are similar to those of Embodiment 1, to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from the styrene monomer and in the grafted state in the grafted modified polypropylene of this embodiment is 1.1%.

[0151] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 1.1%, the grafting efficiency was 11%, the flexural modulus was 1189 MPa, and the melting temperature was 165°C.

[0152] Example 22

[0153] The difference between this embodiment and embodiment 1 is that the maleic anhydride monomer is replaced with a 4-propyleneoxy-2-hydroxybenzophenone monomer (the general structural formula is shown in formula (V), R1 is CH3, R2-R 11 The remaining steps and processes were similar to those in Example 1 to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contained 0.7% of the structural units derived from 4-propyleneoxy-2-hydroxybenzophenone monomers and the structural units in the grafted state.

[0154] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.7%, the grafting efficiency is 9%, the flexural modulus is 1078 MPa, and the melting temperature is 164°C.

[0155] Example 23

[0156] The difference between this embodiment and embodiment 1 is that the maleic anhydride monomer is adjusted to a styrene monomer (the general structural formula is shown in formula (I), R1 is CH3, R2-R8 are CH2CH3), a maleic anhydride monomer (the general structural formula is shown in formula (IV), R1 is CH2CH2CH3, R2 is CH2CH3) and a 4-propyleneoxy-2-hydroxybenzophenone monomer (the general structural formula is shown in formula (V), R1 is CH2COOH, R2-R 11 The grafted modified polypropylene of this embodiment was prepared by mixing monomers (CH2CH3) in a mass ratio of 5:3:5, and the remaining steps and processes were the same as those of Example 1 to obtain the grafted modified polypropylene of this embodiment. The content of structural units derived from styrene monomers and in a grafted state in the grafted modified polypropylene of this embodiment was 0.51%; the content of structural units derived from 4-propyleneoxy-2-hydroxybenzophenone monomers and in a grafted state in the grafted modified polypropylene was 0.31%; and the content of structural units derived from maleic anhydride monomers and in a grafted state in the grafted modified polypropylene was 0.51%.

[0157] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment was 1.4%, the grafting efficiency was 13%, the flexural modulus was 1134 MPa, and the melting temperature was 165°C.

[0158] Example 24

[0159] The difference between this embodiment and embodiment 1 is that the maleic anhydride monomer is adjusted to maleic anhydride monomer (the general structural formula is shown in formula (IV), R1 is CH2CH3, R2 is CH2CH3) and 4-propyleneoxy-2-hydroxybenzophenone monomer (the general structural formula is shown in formula (V), R1 is CH2COOH, R2-R 11 The grafted modified polypropylene of this embodiment was prepared by mixing a mixed monomer of CH2CH3 in a mass ratio of 2:8, and the remaining steps and processes were the same as those of Example 1 to obtain the grafted modified polypropylene of this embodiment. The content of the structural units derived from 4-propyleneoxy-2-hydroxybenzophenone monomers and in a grafted state in the grafted modified polypropylene of this embodiment was 0.48%; the content of the structural units derived from maleic anhydride monomers and in a grafted state in the grafted modified polypropylene was 0.12%.

[0160] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.6%, the grafting efficiency is 9%, the flexural modulus is 1098 MPa, and the melting temperature is 165°C.

[0161] Comparing the grafting effects of the graft-modified polypropylene under the schemes of Example 1 and Examples 21 to 24, the results are shown in Table 3: Table 3 Grafting effect of graft modified polypropylene under the schemes of Example 1 and Example 21 to Example 24

[0162] As can be seen from Tables 1 and 3, the graft-modified polypropylene of the present invention can be simultaneously grafted with multifunctional monomers at multiple sites, thereby achieving high performance of the polypropylene. Specifically, when maleic anhydride monomers are selected for graft-modification of polypropylene, the polarity of the PP can be significantly increased by introducing carboxylic anhydride groups (-CO-O-CO-), thereby improving its compatibility. Secondly, the anhydride groups can chemically react with materials containing amino or hydroxyl groups (such as the amino groups of nylon) to form strong interfacial chemical bonds, thereby significantly improving the mechanical properties of the composite material (such as tensile strength and impact strength). In addition, the grafting of maleic anhydride onto polypropylene can retard the thermal degradation of the polypropylene and increase its heat deformation temperature.

[0163] When styrene monomers are selected to graft-modify polypropylene, the styrene chain segments can reduce the melt viscosity of the modified polypropylene, increase fluidity, and improve processing performance; secondly, styrene monomer-modified polypropylene can enhance impact resistance by forming a microphase separation structure, and the rigid benzene ring of styrene can compensate for the flexibility of the modified polypropylene, thereby increasing modulus and dimensional stability; finally, the introduction of styrene can impart new functions to the modified polypropylene through subsequent reactions (such as sulfonation and bromination), thereby improving the flame retardancy and ion exchange capacity of the modified polypropylene.

[0164] When grafting polypropylene with 4-propyleneoxy-2-hydroxybenzophenone monomers, the 2-hydroxybenzophenone group in AHBP is a classic ultraviolet absorber (UVA), effectively absorbing ultraviolet rays from 290 to 400 nm. This gives the grafted polypropylene excellent UV absorption and light stability. Secondly, AHBP is chemically bonded to the polymer chain, eliminating migration, volatilization, or precipitation issues, achieving permanent UV resistance. Finally, the β-form (hexagonal) of PP offers greater toughness and impact strength than the more common α-form (monoclinic). Many methods for toughening PP include the addition of β-nucleating agents. The introduction of 4-propyleneoxy-2-hydroxybenzophenone monomers effectively promotes the formation of β-crystals, significantly improving the low-temperature impact strength of PP.

[0165] Example 25

[0166] This embodiment differs from Example 1 in that the organic solvent, toluene, is replaced with chlorobenzene. The remaining steps and processes are similar to those of Example 1, to obtain the grafted modified polypropylene of this embodiment. The grafted modified polypropylene of this embodiment contains 0.9% of the structural units derived from maleic anhydride monomers and in a grafted state.

[0167] According to measurements, the grafting rate of the graft-modified polypropylene of this embodiment is 0.9%, the grafting efficiency is 6%, the flexural modulus is 1167 MPa, and the melting temperature is 165°C.

[0168] Comparative Example 2

[0169] The difference between this comparative example and Example 1 is that the organic solvent toluene is changed to water, and the remaining steps and processes are referred to Example 1 to obtain the grafted modified polypropylene of this comparative example. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this comparative example is 0.03%.

[0170] The grafting rate of the graft-modified polypropylene in this comparative example was measured to be 0.03%, the grafting efficiency was 0.3%, the flexural modulus was 1002 MPa, and the melting temperature was 164°C.

[0171] Comparing the grafting effects of the graft-modified polypropylene under different solvent schemes in Example 1, Example 25 and Comparative Example 2, the results are shown in Table 4: Table 4 Grafting effect of grafted modified polypropylene under different solvent schemes

[0172] As can be seen from Table 4, the choice of solvent has a significant impact on the grafting effect of the present invention. This is because the hydrogen atom transfer initiator of the present application can form a homogeneous system with PP in an organic solvent, the monomer diffusion resistance is small, the grafting point distribution is more uniform, and there is no reliance on interface agents. The solution grafting directly acts on the PP molecular chain without the need for additional additives, and the product is purer.

[0173] Comparative Example 3

[0174] This comparative example differs from Example 1 in that the reaction system temperature in step 2) is adjusted to 190° C. The remaining steps are similar to those in Example 1, thereby obtaining the grafted modified polypropylene of this comparative example. The grafted modified polypropylene of this comparative example contains 0.1% structural units derived from maleic anhydride monomers and in a grafted state.

[0175] The results show that the grafting rate of the graft-modified polypropylene in this comparative example is 0.1%, the grafting efficiency is 1%, the flexural modulus is 1009 MPa, and the melting temperature is 164°C.

[0176] Comparative Example 4

[0177] This comparative example differs from Example 1 in that the oxygen introduction time in step 2) is adjusted to within 0.5 h, and the oxygen introduction amount is twice the molar amount of the initiator. The remaining steps and processes are the same as those in Example 1, to obtain the grafted modified polypropylene of this comparative example. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene of this comparative example is 0.05%.

[0178] The results show that the grafting rate of the graft-modified polypropylene in this comparative example is 0.05%, the grafting efficiency is 0.5%, the flexural modulus is 1001 MPa, and the melting temperature is 164°C.

[0179] Comparing the grafting effects of graft-modified polypropylene under different reaction conditions in Example 1, Comparative Examples 3 and 4, the results are shown in Table 5: Table 5 Grafting effect of grafted modified polypropylene under different reaction conditions

[0180] As can be seen from Table 5, the present invention can achieve efficient and controllable grafting under mild conditions (normal pressure) by optimizing the reaction system.

[0181] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for grafting modification of polypropylene, characterized in that: include, A powdered polypropylene monomer and an organic solvent are mixed in a mass ratio of 0.1 to 2:10 to obtain a reaction system. After removing oxygen from the reaction system, the temperature is raised to 20 to 80° C. and an inert gas is introduced. A hydrogen atom transfer initiator in an amount of 0.1% to 15% by mass relative to the polypropylene monomer and a functional monomer in an amount of 0.1% to 25% by mass relative to the polypropylene monomer are sequentially added to the reaction system. After uniform mixing, oxygen in an amount of 1 to 2 times the molar mass of the initiator is gradually introduced within 1 to 3 hours to carry out a solvent grafting reaction for 6 to 24 hours. After the reaction is completed, the product is washed, centrifuged, and dried to obtain a modified grafted polypropylene. The functional monomers include one or more of styrene monomers, maleic anhydride monomers, and 4-propyleneoxy-2-hydroxybenzophenone monomers.

2. The graft modification method of polypropylene according to claim 1, wherein: The organic solvent includes one or more of aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, and special solvents, wherein the aromatic hydrocarbon solvent includes one or more of xylene, toluene, benzene, ethylbenzene, isopropylbenzene, hexane, 1,2,4-trimethylbenzene, chlorobenzene, and 1,2,4-trichlorobenzene; the aliphatic hydrocarbon solvent includes one or more of n-hexane, n-heptane, cyclohexane, decalin, and tetralin; and the special solvent includes one or more of hexafluoroisopropanol and perfluorooctane.

3. The graft modification method of polypropylene according to claim 1, wherein: The hydrogen atom transfer initiator includes one or more of tributylboron initiator, tri-sec-butylborane initiator, triethylboron initiator, triphenylboron initiator, triisobutylboron initiator, triisobutylaluminum initiator, azobisisobutyronitrile initiator, azobisisoheptanenitrile initiator, dimethyl azobisisobutyrate initiator, azobiscyclohexylcarbonitrile initiator, potassium persulfate, and sodium bisulfite; Wherein, the tributyl boron initiator has the general structural formula shown in formula (A); Formula (A); In formula (A), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 12 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The tri-sec-butylborane initiator has the general structural formula shown in formula (B); Formula (B); In formula (B), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 12 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The triethyl boron initiator has the general structural formula shown in formula (C); Formula (C); In formula (C), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R6 are each independently selected from a substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The triphenylboron initiator has the general structural formula shown in formula (D); Formula (D); In formula (D), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 15 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The triisobutylaluminum initiator has the general structural formula shown in formula (E); Formula (E); In formula (E), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R7 are each independently selected from a substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The azobisisobutyronitrile initiator has the general structural formula shown in formula (F); Formula (F); In formula (F), R1 and R2 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R3-R4 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The azobisisoheptanenitrile initiator has the general structural formula shown in formula (G); Formula (G); In formula (G), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 12 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The dimethyl azobisisobutyrate initiator has the general structural formula shown in formula (H); Formula (H); In formula (H), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R8 are each independently selected from a substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; The azobiscyclohexylcarbonitrile initiator has the general structural formula shown in formula (J); Formula (J); In formula (J), R1, R2, and R3 are each independently selected from H, a substituted or unsubstituted C1-C6 alkyl group; R4-R 10 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

4. The graft modification method of polypropylene according to claim 1, wherein: The styrene monomer is a monomeric styrene compound polymerized by free radicals, and is selected from one of the structural formulas shown in any one of formulas (I) to (III); Formula (I); Formula (II); Formula (III); In formula (I), R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R4-R8 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 One of amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; In formula (II), R1, R2, and R3 are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R4-R 10 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups; In formula (III), R1', R2', and R3' are each independently selected from H, substituted or unsubstituted C1-C6 alkyl; R4'-R 10 ' are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

5. The graft modification method of polypropylene according to claim 1, wherein: The maleic anhydride monomer is a monomeric maleic anhydride compound polymerized by free radicals, and its structural formula is shown in formula (IV); Formula (IV); In formula (IV), R1-R2 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 amine, H, halogen, hydroxyl, amino, phosphate, sulfonic acid, carboxyl, wherein the substituted group is selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

6. The method for grafting and modifying polypropylene according to claim 1, wherein: The 4-propyleneoxy-2-hydroxybenzophenone monomer is a 4-propyleneoxy-2-hydroxybenzophenone compound that is polymerized by free radicals, and its structural formula is shown in Formula (V); Formula (V); In formula (V), n is in the range of 1 to 12, R1 and R2 are independently selected from H, substituted or unsubstituted C1-C6 alkyl, R4-R 11 are each independently selected from substituted or unsubstituted C1-C 12 Alkyl, substituted or unsubstituted C3-C 12 Cycloalkyl, substituted or unsubstituted C1-C 12 Alkoxy, substituted or unsubstituted C1-C 12 Ester group, substituted or unsubstituted C1-C 12 The amine, H, halogen, hydroxyl, amino, phosphoric acid, sulfonic acid, carboxyl, substituted groups are selected from C1-C 12 Alkyl, C3-C 12 Cycloalkyl, C1-C 12 Alkoxy, C1-C 12 Ester group, C1-C 12 Amine, halogen, hydroxyl, amino, phosphate, sulfonic acid, and carboxyl groups.

7. The graft-modified polypropylene obtained by the graft-modification method according to any one of claims 1 to 6, characterized in that: The graft-modified polypropylene has a structural formula shown in either formula (VI) or formula (VII); Formula (VI); Formula (VII); In formula (VI), R' is any one of a structural unit derived from copolymerized polypropylene, a structural unit derived from a styrene monomer, a structural unit derived from a maleic anhydride monomer, and a structural unit derived from a 4-propyleneoxy-2-hydroxybenzophenone monomer; In formula (VII), R1', R2', and R1' are independently any one of a structural unit derived from copolymerized polypropylene, a structural unit derived from a styrene monomer, a structural unit derived from a maleic anhydride monomer, and a structural unit derived from a 4-propyleneoxy-2-hydroxybenzophenone monomer.

8. The graft-modified polypropylene according to claim 7, wherein: The copolymerized polypropylene is a propylene copolymer containing ethylene or a higher α-olefin or a mixture thereof; The comonomer of the copolymerized polypropylene is selected from at least one of C2-C8 α-olefins other than propylene; the C2-C8 α-olefins other than propylene include at least one of ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene and 1-octene.

9. The graft-modified polypropylene according to claim 7, wherein: The content of the structural units derived from styrene monomers and in a grafted state in the grafted modified polypropylene is 0.1% to 20% by mass. The content of the structural units derived from maleic anhydride monomers and in the grafted state in the grafted modified polypropylene is 0.1% to 15%; The content of the structural units derived from 4-propyleneoxy-2-hydroxybenzophenone monomers and in a grafted state in the grafted modified polypropylene is 0.1% to 25%.

10. The graft-modified polypropylene according to claim 7, wherein: The graft-modified polypropylene has at least one of the following characteristics: (a) Oxidation induction time ≥ 45 min at 220°C; (b) flexural modulus > 1000 MPa; (c) Melting temperature T m ≥165℃ (d) Ultraviolet radiation transmittance <4% (e) Tensile strain at break at 23°C (50 mm / min) ≥ 500%; (f) Peel strength >260 N / cm at 23°C, peel strength >110 N / cm at 80°C, peel strength >65 N / cm at 110°C, and peel strength >35 N / cm at 140°C; (g) Low temperature impact strength>40KJ / M².

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