Process for the functionalization of polyolefins with maleic anhydride and solid phase grafting modifications thereof

Abstract

The application belongs to the technical field of polymer material preparation, and particularly relates to a maleic anhydride functionalized polyolefin and a solid-phase grafting modification method thereof. The maleic anhydride functionalized polyolefin provided by the application has a grafting monomer with a chemical structure as shown in formula I, and the grafting rate is 6-12%. The grafting monomer cannot occur free radical self-polymerization, and can effectively avoid the decrease of the effective grafting rate of the obtained maleic anhydride functionalized polyolefin caused by the side reaction initiated by the self-polymerization of the grafting monomer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer material preparation, and particularly relates to a maleic anhydride functionalized polyolefin and a method for solid phase graft modification thereof. BACKGROUND

[0002] Polyolefin is a general term of a kind of thermoplastic resin composed of polyethylene (PE), polypropylene (PP), polybutene-1 (PB-1) and other poly-alpha-olefins and copolymers thereof, and is one of the most widely used general-purpose materials at present. Polyolefin has the advantages of light weight, low price, good mechanical processing performance and electrical insulation, and is widely used in films, pipes, plates, fibers, electronic devices and wire and cable, etc. However, the non-polarity and low surface activation energy of polyolefin material greatly reduce its antistatic property, hydrophilicity, colorability and compatibility with polar polymer materials, etc., thereby limiting the application field of polyolefin material. Functional modification of polyolefin to make its molecular chain have polar groups can improve its own shortcomings, which is a relatively simple and effective method to expand its use and open up new application fields. Maleic anhydride (MAH) has become a "star monomer" for modification of polyolefin base material due to its low cost, poor homopolymerization property and high reactivity.

[0003] Solid-phase grafting modification has advantages such as no need for solvent recovery, simple post-processing, and high efficiency and energy saving, making it a current research hotspot with promising industrial applications. Conventional solid-phase grafting methods use maleic anhydride as a monomer, BPO or DCP as an initiator, and polyolefin powder as a matrix to prepare maleic anhydride-functionalized polyolefins through solid-phase grafting reactions. Currently, obtaining functionalized polyolefins with high grafting rates has been a primary research focus. In recent years, some scholars have proposed using supercritical fluid dynamics, ultraviolet light, force, ultrasound, and microwaves to assist ordinary solid-phase grafting methods, improving reaction conditions and reducing side reactions to increase the grafting rate. For example, Zhang Zhiqian et al. grafted MAH onto the surface of PP powder using ultraviolet light solid-phase grafting in a high-pressure reactor, studying the effects of various process conditions on the grafting results, and finding the reaction conditions with the highest grafting rate: MAH mass fraction 2.5%, reaction temperature 30℃, and light irradiation time 3 min. Lin Yanxin et al. conducted a systematic study on the preparation of PP-g-MAH using an ultrasonic-assisted solid-state reaction process, achieving a grafting rate of 5.3% at 75℃ for 40 minutes. While these methods reduce the grafting reaction temperature and shorten the reaction time to some extent, thus increasing the grafting rate, the entire process is complex and introduces special media and equipment, undoubtedly increasing production costs and the difficulty of industrialization. The inventors' team previously developed a graft polymerization method using low-particle-size polyolefin particles with conventional solid-state grafting to obtain a high grafting rate, showing promising application prospects. However, currently, there is a lack of efficient methods for preparing low-particle-size polyolefin particles in industry, preventing the industrialization of this strategy in the short term. Therefore, how to simply and efficiently obtain maleic anhydride functionalized polyolefins with high grafting rates remains a technical challenge to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a maleic anhydride-functionalized polyolefin, the grafted monomer of which has the chemical structure shown in Formula I:

[0005]

[0006] Among them, X 1 and X 2 At least one of them is selected from fluorine, chlorine, bromine, and iodine, when X 1 and X 2 When not all are halogens, one of them is selected from H or C. 1-10 Alkyl, C 3-10 cycloalkyl, C 6-10 Aryl or -C 1-10 Alkyl-C 6-10 Aryl, the C 6-10 Aryl optional C 1-10 Alkyl, C 3-10 Cycloalkyl substitution;

[0007] The grafting rate of the grafting monomer is 6-12%.

[0008] According to an embodiment of the present application, X 1 and X 2 at least one is selected from chlorine or bromine, when X 1 and X 2 are not both chlorine or bromine, one of which is selected from H or C 1-3 alkyl.

[0009] According to an embodiment of the present application, the grafting monomer of formula I is selected from the following compounds:

[0010]

[0011] According to an embodiment of the present application, the grafting rate of the grafting monomer is 6-10%.

[0012] According to an embodiment of the present application, the polyolefin of the maleic anhydride functionalized polyolefin is selected from one, two or more of an ethylene homo- or copolymer, a propylene homo- or copolymer, a butene-1 homo- or copolymer. The comonomer of the copolymer is selected from one, two or more of an alpha-olefin, for example one, two or more of ethylene, 1-propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene.

[0013] As an example, the polyolefin is selected from polyethylene, polypropylene or polybutene-1.

[0014] According to an embodiment of the present application, the maleic anhydride functionalized polyolefin is a propylene functionalized with a grafting monomer of formula I-1, I-2 or I-3.

[0015] The present application also provides a method for preparing the maleic anhydride functionalized polyolefin as described above, using a solid phase grafting method, comprising the following steps:

[0016] The polyolefin, the grafting monomer of formula I, the interfacial agent and the initiator are added into a reaction vessel, and the raw materials are stirred uniformly, and then the solid phase grafting reaction is carried out under the protection of inert gas by heating.

[0017] According to an embodiment of the present application, the polyolefin is subjected to a drying treatment before use, and the drying treatment method is to place the polyolefin into a vacuum oven and heat to 30-80°C, for example 60°C, and vacuum treatment for 1-24 hours, for example 12 hours.

[0018] According to an embodiment of the present application, the amount of the grafting monomer added is 6-18% of the mass of the polyolefin, preferably 8-16%, for example 8%, 10%, 12% or 14%.

[0019] According to the embodiments of the present application, the interfacial agent is selected from halogenated benzene or halogenated C 1-10 alkane, preferably at least one of chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene and carbon tetrachloride.

[0020] According to the embodiments of the present application, the interfacial agent is added in an amount of 3-25%, preferably 5-20%, and more preferably 8-15%, for example 5%, 10%, 20%, by weight of the polyolefin.

[0021] According to the embodiments of the present application, the initiator is selected from free radical initiators, preferably peroxides, and more preferably at least one of dibenzoyl peroxide (BPO), dicumyl peroxide (DCP), t-butyl peroxybenzoate.

[0022] According to the embodiments of the present application, the initiator is added in an amount of 0.8-10%, preferably 1-8%, for example 1%, 1.6%, 2%, by weight of the polyolefin.

[0023] According to the embodiments of the present application, the inert gas is selected from nitrogen, argon.

[0024] According to the embodiments of the present application, the temperature of the solid phase grafting reaction is 80-130°C, and the reaction time is 0.5-24 hours, preferably the temperature is 100-120°C, and the time is 1-4 hours.

[0025] According to the embodiments of the present application, the method further comprises a step of washing and drying the product, and the washing and drying method is washing 3-10 times with ethyl acetate at 60°C, and then vacuum treatment in a vacuum drying oven at 60°C for 1-4 hours.

[0026] The present application also provides the use of the maleic anhydride functionalized polyolefin as described above, including for the preparation of films, pipes, sheets, fibers, electronic devices and wire and cable.

[0027] Advantages:

[0028] (1) The grafting monomer provided by the present application does not undergo free radical self-polymerization, which can effectively avoid the decrease of the effective grafting rate of the obtained maleic anhydride functionalized polyolefin caused by the side reaction initiated by the self-polymerization of the grafting monomer.

[0029] (2) The grafting monomer provided by the present application has excellent physical state stability compared to maleic anhydride, and can be uniformly distributed in the polyolefin system at the grafting reaction temperature, so that the obtained grafting polymer presents uniform light yellow color Figure 2The grafting monomer is not uniformly distributed in the reaction system due to sublimation and condensation of the ordinary maleic anhydride, and thus the color difference of the obtained grafting polymer is large (the product subjected to the grafting reaction is yellow, the product subjected to excessive reaction and degradation is dark yellow, and the polymer not involved in the reaction is white, i.e. the product modified by the ordinary maleic anhydride is a mixture of three states, see Figure 2 in the right graph of FIG. 2.

[0030] (3) The solid-phase grafting modification method provided by the present application can realize controllable grafting rate to some extent by controlling the addition amount of the grafting monomer, and the product obtained under the same formulation has good grafting rate stability, good reproducibility of the method, and stable operation.

[0031] (4) The maleic anhydride functionalized polyolefin provided by the present application has good particle morphology and no odor, and the effective content of the maleic anhydride, i.e. the effective grafting rate, can generally reach 6%, and can reach 9.8% at most. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The infrared spectra of the grafting monomer I-1 (Fig. a), the raw material polypropylene (Orient Macro 4960) (Fig. b), and the maleic anhydride functionalized polypropylene prepared in Example 1 (Fig. c) used in Example 1.

[0033] Figure 2 The photos of the polypropylene sample (Orient Macro 4960) (left), the maleic anhydride functionalized polypropylene prepared in Example 3 (middle), and the maleic anhydride functionalized polypropylene prepared in Comparative Example 1 (right) are shown in FIG. 3.

[0034] TERMS DEFINITION AND EXPLANATION

[0035] Unless otherwise specified, the definitions of the groups and terms in the specification and claims of the present application, including the definitions of the examples, the exemplary definitions, the preferred definitions, the definitions in the tables, the definitions of the specific compounds in the examples, etc. can be combined and integrated with each other. The group definitions and compound structures after such combination and integration shall belong to the scope of the specification of the present application.

[0036] The term "C 1-10"alkyl" is to be understood as meaning a straight-chain or branched saturated monovalent hydrocarbon group having from 1 to 10 carbon atoms, preferably a straight-chain or branched saturated monovalent hydrocarbon group having 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms. Said alkyl group is, for example, a methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1 -methylbutyl, 1 -ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1 -dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1 -methylpentyl, 2-ethylbutyl, 1 -ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1 -dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl group, and the like, or an isomer thereof. In particular, said group has 1, 2, 3, 4, 5, 6 carbon atoms ("C 1-6 "alkyl"), for example a methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl group, more particularly said group has 1, 2 or 3 carbon atoms ("C 1-3 "alkyl"), for example a methyl, ethyl, n-propyl or isopropyl group.

[0037] The term "C 3-10 "cycloalkyl" is to be understood as meaning a saturated monovalent monocyclic or bicyclic hydrocarbon ring having from 3 to 10 carbon atoms. Said C 3-10 cycloalkyl group can be a monocyclic hydrocarbon group, such as a cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl group, or a bicyclic hydrocarbon group, such as a decahydronaphthalenyl group.

[0038] The term "C 6-10 "aryl" is to be understood as meaning a monovalent aromatic or partially aromatic monocyclic, bicyclic or tricyclic hydrocarbon ring having from 5 to 10 carbon atoms, preferably a ring having 6 carbon atoms ("C6aryl"), for example a phenyl group; or a biphenyl group, or a ring having 9 carbon atoms ("C9aryl"), for example an indanyl or indenyl group, or a ring having 10 carbon atoms ("C 10 aryl"), for example a tetrahydronaphthyl, dihydronaphthyl or naphthyl group.

[0039] Said -C 1-10 alkyl-C 6-10 aryl group denotes a radical which consists of an C 1-10 alkyl group and a C 6-10 aryl group which are linked to one another, and the point of attachment of the substituent is the C 1-10 alkyl group. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be further described in detail below in connection with specific examples. It should be understood that the following examples are only illustrative and explanatory of the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope of protection intended by the present application.

[0041] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0042] In the following examples, G MAH Determination method: accurately weigh 1 g of dried maleic anhydride functionalized polyolefin sample, place it in a 250 mL flask, add 80 mL of xylene, heat to reflux until dissolved. After cooling, add excess 0.1 mol / L KOH-ethanol solution, heat to reflux for 2 h, then cool and titrate with 0.1 mol / L HCl-isopropanol solution using phenolphthalein as indicator. Record the amount of base added and the amount of acid consumed for neutralization, and calculate the G MAH .

[0043] G MAH = (c1V1-c2V2) / 2m*9.806% Formula (1)

[0044] In formula (1), c1 is the concentration of KOH-ethanol solution, mol / L; V1 is the volume of excess KOH-ethanol solution added, mL; c2 is the concentration of HCl-isopropanol solution, mol / L; V2 is the volume of HCl-isopropanol solution consumed for titration and neutralization of base, mL; m is the mass of the maleic anhydride functionalized polyolefin sample, g.

[0045] Example 1

[0046] The grafted monomer I-1 has the following structural formula:

[0047]

[0048] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0049] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 8 g of grafting monomer I-1, 1.6 g of dibenzoyl peroxide and 10 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. During the whole process, keep nitrogen continuously flowing in and out, and use dilute alkali solution to absorb the generated hydrogen chloride gas. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 3 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours, to obtain the maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1. The infrared spectra of the grafting monomer I-1, the raw material polypropylene and the product maleic anhydride functionalized polypropylene are as follows: Figure 1 a, b and c are shown in the following table.

[0050] Example 2

[0051] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours for use.

[0052] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 8 g of grafting monomer I-1, 1.6 g of dibenzoyl peroxide and 10 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. During the whole process, keep nitrogen continuously flowing in and out, and use dilute alkali solution to absorb the generated hydrogen chloride gas. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 3 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours, to obtain the maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1. The infrared spectra of the grafting monomer I-1, the raw material polypropylene and the product maleic anhydride functionalized polypropylene are as follows:

[0053] Example 3

[0054] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours for use.

[0055] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 12 g of grafting monomer I-1, 1.6 g of dibenzoyl peroxide and 10 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. Maintain nitrogen continuously throughout the process, and use dilute lye to absorb the generated hydrogen chloride gas. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 8 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours to obtain a maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1. The obtained grafted polymer is shown in the photo Figure 2 As shown in the center graph, the product is uniform light yellow. And through the olfactory test, the product has basically no odor.

[0056] Example 4

[0057] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0058] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 12 g of grafting monomer I-1, 1.6 g of dibenzoyl peroxide and 10 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. Maintain nitrogen continuously throughout the process, and use dilute lye to absorb the generated hydrogen chloride gas. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 8 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours to obtain a maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1. The obtained grafted polymer is shown in the photo

[0059] Example 5

[0060] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0061] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 12 g of grafting monomer I-1, 2.0 g of dibenzoyl peroxide and 10 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. Maintain nitrogen continuous input and output throughout the process, and absorb the generated hydrogen chloride gas with dilute alkali solution. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 8 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours, to obtain a maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1.

[0062] Example 6

[0063] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0064] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 12 g of grafting monomer I-1, 2.0 g of dibenzoyl peroxide and 10 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. Maintain nitrogen continuous input and output throughout the process, and absorb the generated hydrogen chloride gas with dilute alkali solution. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 8 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours, to obtain a maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1.

[0065] Example 7

[0066] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0067] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 12 g of grafting monomer I-1, 1.6 g of dibenzoyl peroxide and 5 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. Maintain nitrogen continuously throughout the process, and use dilute lye to absorb the generated hydrogen chloride gas. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 8 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours to obtain a maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1.

[0068] Example 8

[0069] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0070] Take 100 g of the above polypropylene powder into a 500 mL reactor, vacuum and replace with nitrogen for 5 times; take 100 mL flask, add 12 g of grafting monomer I-1, 1.6 g of dibenzoyl peroxide and 5 g of chlorobenzene to stir into a uniform solution; use a syringe to slowly inject the above solution into the reactor, and start stirring; then heat to 110°C, react for 2 hours. Maintain nitrogen continuously throughout the process, and use dilute lye to absorb the generated hydrogen chloride gas. Post-processing: after the reaction system is cooled to room temperature, open the reactor and take out the product; add 200 mL of ethyl acetate to the product, heat to 60°C, stir for 10 minutes, and filter; repeat the above washing process 8 times; finally, place the filter cake in a vacuum drying oven at 60°C for 2 hours to obtain a maleic anhydride functionalized polyolefin sample. The test results of the grafting rate are shown in Table 1.

[0071] Example 9

[0072] Grafting monomer I-2 has the following structural formula:

[0073]

[0074] Take about 1 kg of polypropylene powder (Dongfang Hongye 225) and place it in a vacuum oven, heat to 60°C, and vacuum treat for 12 hours.

[0075] 100g of the above polypropylene powder was weighed and added to a 500mL reactor. The reactor was evacuated and purged with nitrogen five times. 12g of graft monomer I-2, 1.6g of dicumyl peroxide, and 10g of o-dichlorobenzene were added to a 100mL flask and stirred to form a homogeneous solution. The solution was slowly injected into the reactor using a syringe, and stirring was started. The temperature was then raised to 120℃, and the reaction was carried out for 1 hour. Nitrogen gas was continuously introduced and removed throughout the process, and the hydrogen bromide gas generated was absorbed with dilute alkaline solution. Post-treatment: After the reaction system cooled to room temperature, the reactor was opened, and the product was removed. 200mL of ethyl acetate was added to the product, the temperature was raised to 60℃, and the mixture was stirred for 10 minutes and filtered. The washing process was repeated eight times. Finally, the filter cake was placed in a vacuum drying oven at 60℃ for 2 hours to obtain the maleic anhydride functionalized polyolefin sample. The grafting rate test results are shown in Table 1.

[0076] Example 10

[0077] The graft monomer I-3 has the following structural formula:

[0078]

[0079] Take about 1 kg of polypropylene powder (Sinopec 150) and place it in a vacuum oven. Heat it to 60°C and vacuum treat it for 12 hours before use.

[0080] 100g of the above polypropylene powder was weighed and added to a 500mL reactor, and the reactor was evacuated and purged with nitrogen five times. 12g of graft monomer I-2, 1.6g of tert-butyl peroxide, and 10g of 1,2,4-trichlorobenzene were added to a 100mL flask and stirred to form a homogeneous solution. The solution was slowly injected into the reactor using a syringe, and stirring was started. The temperature was then raised to 100℃, and the reaction was carried out for 3 hours. Nitrogen gas was continuously introduced and removed throughout the process, and the hydrogen bromide gas generated in the reaction was absorbed with dilute alkaline solution. Post-treatment: After the reaction system cooled to room temperature, the reactor was opened, and the product was removed. 200mL of ethyl acetate was added to the product, the temperature was raised to 60℃, and the mixture was stirred for 10 minutes and filtered. The washing process was repeated eight times. Finally, the filter cake was placed in a vacuum drying oven at 60℃ for 2 hours to obtain the maleic anhydride functionalized polyolefin sample. The grafting rate test results are shown in Table 1.

[0081] Comparative Example 1

[0082] Take about 1 kg of polypropylene powder (Dongfang Hongye 4960) and place it in a vacuum oven. Heat it to 60℃ and vacuum treat it for 12 hours before use.

[0083] Weigh 100g of the above polypropylene powder and add it to a 500mL reactor. Vacuum the reactor five times to purge with nitrogen. Add 12g of maleic anhydride, 1.6g of benzoyl peroxide, and 10g of chlorobenzene to a 100mL flask and stir until a homogeneous solution is formed. Slowly inject the solution into the reactor using a syringe and start stirring. Then heat to 110℃ and react for 2 hours. Throughout the process, continuously purge and vent nitrogen, and absorb the generated hydrogen chloride gas with dilute alkali solution. Post-treatment: After the reaction system cools to room temperature, open the reactor and remove the product. Add 200mL of ethyl acetate to the product, heat to 60℃, stir for 10 minutes, and filter. Repeat the washing process eight times. Finally, place the filter cake in a vacuum drying oven at 60℃ for 2 hours to obtain the maleic anhydride-functionalized polyolefin sample. The grafting rate test results are shown in Table 1. A photograph of the maleic anhydride-functionalized polypropylene product is shown below. Figure 2 As shown in the middle right figure. (By...) Figure 2 As shown in the middle right figure, the grafted polymer has a large color difference (the product that has undergone the grafting reaction is yellow, the product that has degraded due to excessive reaction is burnt yellow, and the polymer that has not participated in the reaction is white), that is, the product of ordinary maleic anhydride modification is a mixture of the three states.

[0084] Table 1. Grafting rate characterization results of maleic anhydride functionalized polyolefin samples

[0085]

[0086] In the table above, "second" and "third" with experimental data indicate that the second and third experiments were repeated, while "-" indicates that the above repeated experiments were not performed.

[0087] Analysis of Examples 1-4 shows that as the amount of grafting monomer provided by the present invention increases, the grafting rate gradually increases, that is, the maleic anhydride content of the obtained maleic anhydride functionalized polyolefin gradually increases; when the amount of grafting monomer added reaches 12% (mass ratio), the grafting reaction is basically saturated, and further increasing the amount of grafting monomer added (Example 4) no longer significantly increases the grafting rate of the obtained polymer.

[0088] Analysis of Examples 3, 5, and 6 shows that the amount of initiator added has a significant impact on the grafting rate. For this reaction system, 1.6% (mass ratio) of benzoyl peroxide is a better ratio; increasing or decreasing this ratio will reduce the grafting rate of the product.

[0089] Analysis of Examples 3, 7, and 8 shows that the amount of interfacial agent added has a significant impact on the grafting rate. For this reaction system, 10% (by mass) of chlorobenzene is an optimal ratio; increasing or decreasing this ratio will reduce the grafting rate of the product.

[0090] Analysis of Examples 3, 9, and 10 shows that using graft monomers with other structures improved by this invention helps to obtain maleic anhydride-functionalized polyolefins with high grafting rates. Other types of free radical initiators, such as dicumyl peroxide and tert-butyl peroxide, can be used in this system to prepare maleic anhydride-functionalized polyolefins with high grafting rates, indicating that this system has good applicability as a free radical initiator. Other types of interface agents, such as o-dichlorobenzene and 1,2,4-trichlorobenzene, can also be used in this system to prepare maleic anhydride-functionalized polyolefins with high grafting rates. Within a certain range, to cope with different production conditions, the reaction time can be shortened by increasing the reaction temperature or extended by decreasing the reaction temperature. Both methods can achieve the preparation of maleic anhydride-functionalized polyolefins with high grafting rates.

[0091] Analysis of Examples 3, 9, 10 and Comparative Example 1 shows that, compared with ordinary maleic anhydride, the grafting monomer provided by the present invention is more conducive to obtaining maleic anhydride functionalized polyolefins with high grafting rates when applied to solid-phase grafting reactions; moreover, when using the grafting monomer provided by the present invention for solid-phase grafting reactions, the obtained maleic anhydride functionalized polyolefins have stable maleic anhydride content, and the experiment has excellent repeatability.

[0092] In summary, the grafting monomers provided by this invention are more suitable for solid-phase grafting reactions to prepare maleic anhydride-functionalized polyolefins with high grafting rates compared to ordinary maleic anhydride. Furthermore, the preparation of maleic anhydride-functionalized polyolefins using the grafting monomers and solid-phase grafting method provided by this invention exhibits excellent repeatability, ensuring the stability of product performance. Therefore, the technical solution provided by this invention employs simple equipment and processes, and can obtain grafted polymers with high maleic anhydride content without the addition of external media, making it promising for industrial application in the near future.

[0093] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A maleic anhydride-functionalized polyolefin, characterized in that, Its grafted monomers have the chemical structure shown in Formula I: Among them, X 1 and X 2 At least one is selected from chlorine or bromine, when X 1 and X 2 When not all are halogens, one of them is selected from C. 1-6 alkyl; The grafting rate of the grafted monomers is 6-12%; The maleic anhydride-functionalized polyolefin is selected from polyethylene, polypropylene, or polybutene-1.

2. The maleic anhydride-functionalized polyolefin according to claim 1, characterized in that, In formula I, X 1 and X 2 At least one is selected from chlorine or bromine, when X 1 and X 2 When not all are chlorine or bromine, one of them is selected from C. 1-3 alkyl.

3. The maleic anhydride-functionalized polyolefin according to claim 1 or 2, characterized in that, The graft monomers shown in Formula I are selected from the following compounds:

4. The maleic anhydride-functionalized polyolefin according to claim 1 or 2, characterized in that, The grafting rate of the grafted monomers is 6-10%.

5. The method for preparing maleic anhydride functionalized polyolefins according to any one of claims 1-4, characterized in that, The solid-phase grafting method includes the following steps: Polyolefin, grafting monomer shown in Formula I, interfacial agent and initiator are added to the reaction vessel. After the raw materials are stirred evenly, the solid-phase grafting reaction is carried out under the protection of inert gas. The interface agent is selected from halogenated benzene or halogenated C. 1-10 Alkanes; The initiator is selected from free radical initiators.

6. The preparation method according to claim 5, characterized in that, The polyolefin is dried before the reaction. The drying method is to put the polyolefin into a vacuum oven and heat it to 30-80°C, and vacuum treat it for 1-24 hours.

7. The preparation method according to claim 5, characterized in that, The amount of grafted monomer added is 6 to 18% of the mass of the polyolefin.

8. The preparation method according to claim 5, characterized in that, The interface agent is selected from at least one of chlorobenzene, o-dichlorobenzene, 1,2,4-trichlorobenzene and carbon tetrachloride.

9. The preparation method according to claim 5, characterized in that, The amount of the interface agent added is 3 to 25% of the mass of the polyolefin.

10. The preparation method according to claim 5, characterized in that, The initiator is selected from at least one of benzoyl peroxide (BPO), dicumyl peroxide (DCP), and tert-butyl peroxide.

11. The preparation method according to claim 5, characterized in that, The amount of initiator added is 0.8 to 10% of the mass of the polyolefin.

12. The preparation method according to claim 5, characterized in that, The temperature for the solid-phase grafting reaction is 80–130℃, and the reaction time is 0.5–24 hours.

13. Use of the maleic anhydride functionalized polyolefin according to any one of claims 1-4 in the preparation of films, pipes, sheets, fibers, electronic devices and wires and cables.

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