Acrylate modified polypropylene and its preparation method and application

Abstract

The present invention relates to a method for preparing acrylate-modified polypropylene, comprising the following steps: 1) contacting a first olefin monomer with a catalyst to conduct a first polymerization to obtain a slurry containing the first polymer; the first olefin monomer is a mixture of propylene and ethylene, or one of propylene, wherein the molar percentage of propylene in the mixture is ≥96%; 2) contacting a second olefin monomer with a catalyst to conduct a second polymerization to obtain a slurry containing the second polymer; the second olefin monomer is selected from an alkyl acrylate with a carbon chain length of C1 to C18; 3) mixing the slurry containing the first polymer and the slurry containing the second polymer to conduct a third polymerization; and 4) adding a chain terminator to terminate the reaction to obtain acrylate-modified polypropylene. The preparation method provided by the present invention utilizes a specific catalyst system to separately control the self-polymerization process of the two monomers, and then copolymerizes the self-polymerization products to obtain acrylate-modified polypropylene with excellent comprehensive properties.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer preparation, and in particular relates to acrylate-modified polypropylene and a preparation method and application thereof. Background Art

[0002] Polypropylene is one of the most widely used polymers, boasting excellent mechanical and processing properties and being recognized as an environmentally friendly material. However, polypropylene also has significant drawbacks, such as poor cold resistance and low low-temperature impact strength. Furthermore, due to its non-polar molecular structure, its compatibility and adhesion with polar materials are poor, significantly limiting its application.

[0003] For years, many researchers have sought to address these technical challenges. Some have attempted to improve these properties by introducing polar groups into polypropylene molecules through chemical modification. However, because polypropylene is non-polar, it is difficult to incorporate large amounts of polar group-containing monomers into polypropylene molecules through chemical modification methods such as grafting.

[0004] Some researchers also hope to improve their performance by physically modifying them and blending them with other polymers or additives. Prior art blending methods involve separately polymerizing polymers to obtain copolymers with different properties, and then blending these two or more copolymers with different properties to form an olefin copolymer composition. This method modifies the properties of olefin polymers through blending, but compatibility between polymers of different polarities is difficult. Furthermore, because polymer molecules themselves are inherently fluid, even if polymers appear temporarily compatible and their performance appears to meet requirements, over time, the different polymer molecules migrate between each other. In severe cases, the molecules that make up the blend may migrate into two phases, seriously affecting product performance.

[0005] Patents have also reported that reactor blending can be used, that is, preparing different polymers in different reactors, and then flowing the melts or solutions of various polymers together to blend them. Compared with general melt blending, this method has more uniform performance; however, this type of reactor blend still makes it difficult to fundamentally obtain high-value-added olefin polymers with excellent comprehensive performance at the molecular structure level. Summary of the Invention

[0006] Based on the above, the object of the present invention is to provide a method for preparing acrylate-modified polypropylene, which can produce acrylate-modified polypropylene with excellent performance.

[0007] To this end, the present invention provides a method for preparing acrylate-modified polypropylene, which comprises the following steps:

[0008] 1) contacting a first olefin monomer with a catalyst to perform a first polymerization to obtain a slurry containing a first polymer; the first olefin monomer is propylene, or a mixture of propylene and ethylene, wherein the molar percentage of propylene in the mixture is ≥96%;

[0009] 2) contacting a second olefin monomer with a catalyst to perform a second polymerization to obtain a slurry containing a second polymer; the second olefin monomer is selected from an alkyl acrylate, wherein the carbon chain length of the alkyl acrylate is C1 to C18;

[0010] Preferably, the catalyst includes a main catalyst and a co-catalyst; the chemical structure of the main catalyst is preferably as shown below:

[0011]

[0012] In the above formula, R1 and R2 are independently selected from one of a C1-C20 alkyl group, a C3-C20 cycloalkyl group, and a C6-C20 aryl group; R3 and R4 are the same or different and are independently selected from one of a hydrogen atom, a C1-C20 alkyl group, a C3-C20 cycloalkyl group, and a C6-C20 aryl group; X is selected from Cl, Br, methyl, or ethyl; M is selected from titanium, zirconium, hafnium, vanadium, rhodium, iron, nickel, cobalt, neodymium, palladium, or yttrium;

[0013] The co-catalyst includes an organometallic aluminum compound;

[0014] The ratio of the co-catalyst to the main catalyst is 400 to 1000:1 by mass;

[0015] 3) mixing the slurry containing the first polymer and the slurry containing the second polymer to perform a third polymerization;

[0016] 4) Adding a chain terminator to terminate the reaction to obtain acrylate-modified polypropylene.

[0017] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0018] Preferably, in the aforementioned method, the co-catalyst is selected from at least one of trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum or methylaluminoxane.

[0019] Preferably, in the aforementioned method, in the first polymerization, the amount of the main catalyst is 0.002 to 0.008% by mass of the first olefin monomer; and the ratio of the co-catalyst to the main catalyst is 400 to 800:1.

[0020] Preferably, in the aforementioned method, the reaction temperature of the first polymerization is 40-70° C., and the reaction pressure is 0.5-3.0 MPa.

[0021] Preferably, in the aforementioned method, the weight average molecular weight of the first polymer is ≤100,000.

[0022] Preferably, in the aforementioned method, the alkyl acrylate is selected from at least one of methyl methacrylate, methyl acrylate or butyl acrylate.

[0023] Preferably, in the aforementioned method, in the second polymerization, the amount of the main catalyst is 0.001 to 0.002% by mass of the second olefin monomer; and the ratio of the co-catalyst to the main catalyst is 700 to 1000:1.

[0024] Preferably, in the aforementioned method, the reaction temperature of the second polymerization is 60-80° C., and the reaction pressure is 1.0-2.0 MPa.

[0025] Preferably, in the aforementioned method, the weight average molecular weight of the second polymer is 5,000 to 10,000.

[0026] Preferably, in the aforementioned method, the mass ratio of the first polymer to the second polymer is 4 to 9:1.

[0027] Preferably, in the aforementioned method, the polymerization reactors for the first polymerization, the second polymerization and the third polymerization are loop reactors and / or tank reactors.

[0028] Preferably, in the aforementioned method, in steps (1) and (2), the catalyst feed further comprises the following steps:

[0029] 11) uniformly mixing the catalyst and the solvent to obtain a catalyst premix solution;

[0030] 12) The catalyst premix liquid is sequentially metered, conveyed, and buffered before being introduced into a polymerization reactor to respectively perform a first polymerization on the first olefin monomer and a second polymerization on the second olefin monomer; wherein the metering, conveying, and buffering of the premix liquid components are controlled to be uniform, and the pressure of the buffer tank is controlled to be the same as the pressure in the polymerization reactor.

[0031] Preferably, in the aforementioned method, the solvent is selected from at least one of n-hexane, n-heptane or toluene.

[0032] Preferably, in the aforementioned method, an anti-scaling agent is added during the first polymerization, the second polymerization and / or the third polymerization.

[0033] Preferably, in the aforementioned method, the reaction temperature of the third polymerization is 40-80° C., and the reaction pressure is 0.5-3.0 MPa.

[0034] Preferably, in the aforementioned method, the first polymerization, the second polymerization and the third polymerization are all carried out under an inert gas atmosphere.

[0035] Preferably, in the aforementioned method, the chain terminator is an ethanol solution of hydrochloric acid.

[0036] The purpose of the present invention and the technical problems solved therein are also achieved by adopting the following technical solutions: According to the present invention, an acrylate-modified polypropylene prepared according to the above method is provided.

[0037] The purpose of the present invention and the technical problems solved therein are also achieved by the following technical solutions: A compatibilizer proposed in the present invention comprises the aforementioned acrylate-modified polypropylene and is applied to a blend of polyacrylate and polypropylene to improve their compatibility.

[0038] The purpose of the present invention and the technical problems solved therein are also achieved by the following technical solutions: An adhesive proposed by the present invention comprises the aforementioned acrylate-modified polypropylene and is used to bond polypropylene materials to polar substrates to improve their bonding strength.

[0039] By means of the above technical solution, the acrylate-modified polypropylene and its preparation method and application proposed in the present invention have at least the following advantages:

[0040] (1) The preparation method of acrylate-modified polypropylene provided by the present invention controls the polymerization process of propylene or a mixture of propylene and ethylene, and controls the polymerization process of alkyl acrylate monomers, and then copolymerizes the first polymerized polypropylene molecules and the second polymerized polyacrylate molecules to obtain polypropylene containing long polypropylene blocks and short polyacrylate blocks in the molecular chain. The polypropylene has excellent comprehensive performance. At the same time, by controlling the catalyst feeding method, the influence of the catalyst feeding process on the polymerization reaction can be minimized, so that the process conditions of the polymerization reaction are controlled, and high-performance polypropylene with a designable molecular structure is obtained, thereby improving the uniformity of the product molecular structure and the comprehensive performance. At the same time, it can also avoid the blockage of the feed pipeline, improve production efficiency, and thus be more suitable for practical use.

[0041] (2) The method for preparing acrylate-modified polypropylene proposed in the present invention can effectively catalyze the self-polymerization of propylene or its mixture with ethylene in the first polymerization and the self-polymerization of acrylate monomer in the second polymerization by rationally selecting and applying a fully heterocyclic non-metallocene compound as a catalyst. The method can also copolymerize the polypropylene with a controlled molecular weight obtained in the first polymerization and the polyacrylate with a controlled molecular weight obtained in the second polymerization. The catalyst has high catalytic activity for the homopolymerization and copolymerization of polypropylene and polyacrylate, and has excellent copolymerization performance. The catalyst can be used in the structural design of high-value-added products such as polypropylene and in the polymer manufacturing process to obtain acrylate-modified polypropylene with excellent comprehensive performance. The two blocks are chemically bonded at the molecular structure level, and the excellent performance of the acrylate-modified polypropylene can be maintained durably.

[0042] (3) The acrylate-modified polypropylene proposed in the present invention introduces long-chain alkyl groups into the side chains of the molecular structure of polypropylene. The long-chain alkyl groups are soft segments that are largely filled between the polypropylene molecular chains, which can effectively improve the brittleness and low-temperature impact resistance of the polypropylene itself. At the same time, the large number of ester groups connected to the main chain of the molecule have strong polarity, which makes the polypropylene exhibit good compatibility and adhesion when blended with other polar polymers. Moreover, the long-chain alkyl groups and the ester groups are chemically bonded at the molecular structure level, which can durably maintain the excellent performance of the polypropylene. DETAILED DESCRIPTION

[0043] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and processes. However, the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments where specific conditions are not specified are generally based on conventional conditions.

[0044] The preparation method of acrylate-modified polypropylene proposed in the present invention comprises the following steps:

[0045] 1) contacting a first olefin monomer with a catalyst to perform a first polymerization to obtain a slurry containing a first polymer; the first olefin monomer is propylene, or a mixture of propylene and ethylene, wherein the molar percentage of propylene in the mixture is ≥96%;

[0046] 2) contacting a second olefin monomer with a catalyst to perform a second polymerization to obtain a slurry containing a second polymer; the second olefin monomer is selected from an alkyl acrylate, wherein the carbon chain length of the alkyl acrylate is C1 to C18;

[0047] 3) mixing the slurry containing the first polymer and the slurry containing the second polymer to perform a third polymerization;

[0048] 4) adding a chain terminator to terminate the reaction, filtering, and washing to obtain acrylate-modified polypropylene.

[0049] The first polymerization and the second polymerization described in the present invention are independent polymerization reactions and there is no difference in the polymerization order.

[0050] The catalyst includes a main catalyst and a co-catalyst; the chemical structure of the main catalyst is shown below:

[0051]

[0052] In the above formula, R1 and R2 are independently selected from one of a C1-C20 alkyl group, a C3-C20 cycloalkyl group and a C6-C20 aryl group; R3 and R4 are the same or different and are independently selected from one of a hydrogen atom, a C1-C20 alkyl group, a C3-C20 cycloalkyl group and a C6-C20 aryl group; X is selected from Cl, Br, methyl or ethyl; M is selected from titanium, zirconium, hafnium, vanadium, rhodium, iron, nickel, cobalt, neodymium, palladium or yttrium.

[0053] The chemical structure of the main catalyst is a fully heterocyclic ring with multiple alkyl substituents connected to it; the main ring structure of the fully heterocyclic ring is composed of three heteroatoms, Si, N and N, and a transition metal atom M selected from titanium, zirconium, hafnium, vanadium, rhodium, iron, nickel, cobalt, neodymium, palladium or yttrium. The catalyst with this structure can effectively catalyze the self-polymerization of ethylene, the self-polymerization of propylene, the copolymerization reaction of ethylene and polar olefin monomers, and the copolymerization reaction of propylene and polar olefin monomers. The catalyst has high catalyst activity and excellent copolymerization performance, and the prepared polymer has good performance.

[0054] The main catalyst of this structure can be directly combined with the co-catalyst to catalyze olefin polymerization, or the main catalyst can be pre-loaded and then used in combination with the co-catalyst. The loading method of the main catalyst is not specifically limited, and any loading method in the prior art can be used. Whether to load and how to load can be determined according to actual needs.

[0055] Substituents are attached to the three heteroatoms of the main ring structure; the substituents are independently selected and are not mutually restrictive. Generally, R1 and R2 are independently selected from one of a C1-C20 alkyl group, a C3-C20 cycloalkyl group, and a C6-C20 aryl group; and R3 and R4 are independently selected from one of a hydrogen atom, a C1-C20 alkyl group, a C3-C20 cycloalkyl group, and a C6-C20 aryl group.

[0056] The technical solution of the present invention adopts the above-mentioned non-metallocene catalyst as its main catalyst. Its main structure is a complex containing more heteroatoms. Compared with complexes containing only single heteroatoms (such as only oxygen, nitrogen, etc.), its structure has more variability and greater room for adjustment in regulating the structure and performance of the polymer. Moreover, the coordinating atoms of the main catalyst are nitrogen, nitrogen, and silicon, and the oxygen affinity of the central metal atom M is relatively weak. This structure is easier to achieve copolymerization of olefins and polar monomers, thereby synthesizing functional polyolefin materials with excellent performance. At the same time, in addition to having high polymerization activity, the main catalyst also has the advantages of good particle morphology and narrow particle size distribution. This type of main catalyst is very suitable for gas phase polymerization and bulk polymerization processes of propylene.

[0057] The preparation method of the catalyst is described in CN201611257991.7:

[0058] a. preparing a ligand compound;

[0059] b. reacting the ligand compound and the transition metal compound in an organic solvent at a certain molar ratio, and crystallizing to obtain the fully heterocyclic non-metallocene compound;

[0060] Wherein, the structural formula of the ligand compound is as follows:

[0061]

[0062] In the above formula, R1 and R2 are independently selected from one of a C1-C20 alkyl group, a C3-C20 cycloalkyl group and a C6-C20 aryl group; R3 and R4 are independently selected from one of a hydrogen atom, a C1-C20 alkyl group, a C3-C20 cycloalkyl group and a C6-C20 aryl group.

[0063] Preferably, R1 is selected from isopropyl, phenyl, 2,6-dimethylphenyl, benzyl, cyclohexyl or cyclopentyl; R2 is selected from methyl, isopropyl, phenyl or 2,6-dimethylphenyl; R3 is selected from ethyl, phenyl, benzyl, n-hexyl, cyclohexyl, cyclopentyl, isooctyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 4-fluorophenyl, 2,6-difluorophenyl or 2,4,6-trifluorophenyl; R4 is selected from methyl, ethyl, phenyl, benzyl, n-hexyl, cyclohexyl, cyclopentyl, isooctyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 4-fluorophenyl, 2,6-difluorophenyl or 2,4,6-trifluorophenyl.

[0064] Preferably, R1, R2, R3 and R4 in the ligand compound have the following combinations: R1, R2, R3 and R4 are all phenyl groups; R1, R3 and R4 are benzyl groups, and R2 is methyl; R1, R3 and R4 are cyclohexyl groups, and R2 is methyl; R1, R2 and R3 are phenyl groups, and R4 is cyclopentyl; R1 is cyclopentyl, R2 is methyl, and R3 and R4 are all phenyl groups; R1 and R2 are all phenyl groups, and R3 and R4 are all ethyl groups; R1 and R2 are all isopropyl groups, R3 is phenyl groups, and R4 is methyl; R1 and R2 are all 2,6-dimethylphenyl groups, and R3 and R4 are all phenyl groups; R1, R3 and R4 are all 2,6-dimethylphenyl groups, and R2 is methyl; R1 is 2,6-dimethylphenyl groups, R2 is methyl, and R3 and R4 are all 2,4,6-trimethylphenyl groups; R R1 is 2,6-dimethylphenyl, R2 is methyl, R3 and R4 are both phenyl; R1 is 2,6-dimethylphenyl, R2 is methyl, R3 and R4 are both cyclopentyl; R1 is 2,6-dimethylphenyl, R2 is methyl, R3 and R4 are both isooctyl; R1 is 2,6-dimethylphenyl, R2 is methyl, R3 and R4 are both n-hexyl; R1 is phenyl, R2 is methyl, R3 and R4 are both 2,4,6-trifluorophenyl; R1 is phenyl, R2 is methyl, R3 and R4 are both 2,6-difluorophenyl; R1 is phenyl, R2 is methyl, R3 and R4 are both 2,4,6-trifluorophenyl; R1 is phenyl, R2 is methyl, R3 and R4 are both 4-fluorophenyl; R1 is phenyl, R2 is methyl, R3 and R4 are both 2,4,6-trifluorophenyl.

[0065] The preparation method of the ligand compound is as follows:

[0066] 1) reacting a primary amine compound having the general formula R2NH2 or R3NH2 with an equimolar amount of a Grignard reagent at 0-70°C for 1-10 hours, preferably at 10-50°C for 2-4 hours;

[0067] 2) adding an organosilicon compound in an amount of one-half of the primary amine compound, wherein the organosilicon compound conforms to the general formula R1R2SiX2, and reacting at 0-70°C for 1-5 hours, more preferably at 10-50°C for 2-4 hours, to obtain the ligand compound.

[0068] The reaction conditions of the ligand compound and the transition metal compound are as follows:

[0069] (1) The molar ratio of the ligand compound to the transition metal compound is 1:1 to 2, preferably 1:1 to 1.5;

[0070] (2) the organic solvent is preferably toluene;

[0071] (3) The reaction temperature is -50°C to 100°C, preferably 0°C to 90°C, more preferably 30°C to 70°C;

[0072] (4) The reaction time is 1 to 10 hours, preferably 2 to 10 hours, more preferably 3 to 5 hours.

[0073] The chemical structure of the transition metal compound can be expressed as MXn, wherein X is selected from Cl, Br, methyl or ethyl; M is selected from titanium, zirconium, hafnium, vanadium, rhodium, iron, nickel, cobalt, neodymium, palladium or yttrium; and n is a positive integer.

[0074] In the catalyst used in the present invention, the co-catalyst can be an organic metal aluminum compound; further, the organic metal aluminum compound can be an alkyl aluminum or an alkyl aluminum hydrolyzate alkyl aluminoxane; further, the co-catalyst is selected from at least one of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-hexylaluminum or methyl aluminoxane.

[0075] When the main catalyst and the cocatalyst are used for catalytic polymerization, they can effectively catalyze propylene homopolymerization, propylene and ethylene copolymerization, acrylate homopolymerization and propylene and acrylate copolymerization to obtain polypropylene with excellent comprehensive performance and high added value.

[0076] In terms of mass ratio, the ratio of the co-catalyst to the main catalyst is 400 to 1000:1.

[0077] The acrylate-modified polypropylene obtained by the technical solution of the present invention comprises a long block of propylene units and a short block of acrylate units on its molecular main chain, and the two blocks are connected in the form of chemical bonds. The molecular formula of acrylic acid is CH2=CHCOOH, wherein the H bond in the carbonyl group can be replaced by an alkyl group of C1 to C18, collectively referred to as acrylate. The acrylate molecular structure contains a semi-conjugated carbon-carbon double bond and an active ester functional group. In the functional group -COO, both Os are connected to C, one of the carbon-oxygen bonds is a double bond, and the other is a single bond. It can be seen from the chemical structure of the acrylate molecule that the carbon-carbon double bond therein can self-polymerize or copolymerize with other monomers; in the acrylate-modified polypropylene, the acrylate unit is connected to the main molecular chain of the polymer in the form of an open carbon-carbon double bond. Therefore, in the acrylate-modified polypropylene, the acrylate units may also be located at the ends of the molecular chains. However, generally speaking, the number of acrylate units connected to the main chain of the molecular chain is greater than the number of acrylate units connected to the ends of the molecular chain. The length of the connection and the length of the short block can be designed and controlled by process parameters. The connection position can be achieved by controlling the conditions of the third polymerization process and the reactivity ratio of the propylene unit and the acrylate unit in the reaction system.

[0078] The ester group is affected by the carbonyl structure in the carbon-oxygen double bond within the functional group. -COOR is an electron-withdrawing group. Therefore, this polymer unit can impart polarity to polypropylene, which can greatly improve the performance of polypropylene that is difficult to be compatible with other materials and difficult to bond with other materials. At the same time, after the acrylate unit is inserted into the polymer molecular chain, the alkyl group connected to the ester group is a soft monomer, which can fill between the polypropylene molecular chains, giving the polypropylene flexibility and low-temperature impact resistance.

[0079] Preferably, the short block of the acrylate unit may be located in the middle of the molecular chain or at the end of the molecular chain; wherein the content of the acrylate unit located in the middle of the molecular chain is greater than the content of the acrylate unit located at the end of the molecular chain.

[0080] The insertion position and the number of the acrylic acid ester units are determined by 13 C nuclear magnetic resonance method was used for measurement.

[0081] The number of acrylate units incorporated into the polypropylene backbone should be sufficient to achieve the desired modification effect. However, this number should not be too high, both for cost reasons and to avoid degrading the inherent properties of polypropylene. Generally, the mole percentage of acrylate units in the polymer is preferably controlled to approximately 5.0% to 10.0% by mole, based on polymerization process conditions.

[0082] The molecular weight distribution of the polypropylene was evaluated by gel permeation chromatography (GPC).

[0083] The polymerization process and molecular weight level of the polypropylene can be adjusted according to the target application. When the polymer is intended for use in aqueous dispersion products such as adhesives and coatings, solution polymerization can be used to polymerize it into a polymer with a lower molecular weight for easier subsequent use. When the polymer is intended for use in products such as resins and plastics, bulk polymerization can be used to polymerize it into a copolymer with a higher molecular weight to meet the typical uses of polypropylene, resulting in a polypropylene product with improved compatibility, adhesion, flexibility, and low-temperature impact resistance, while still maintaining the excellent properties of polypropylene itself.

[0084] In the technical solution of the present invention, short blocks of acrylate units and long blocks of propylene units are incorporated into the main chain of the polymer molecular chain, rather than directly mixing acrylate monomers and propylene monomers and randomly incorporating them into the molecular chain. This allows the two monomers to form a stable and controlled molecular structure from a microscopic perspective, and to fuse into a uniformly distributed organic whole in terms of phase state. This keeps the molecular structure and comprehensive properties of the polypropylene under control and substantially consistent with the performance designed by technicians.

[0085] Preferably, the preparation method further comprises the following steps: 1) uniformly mixing the catalyst and the solvent to obtain a catalyst premix; 2) sequentially metering, conveying and buffering the catalyst premix into a polymerization reactor to respectively perform a first polymerization on the first olefin monomer and a second polymerization on the second olefin monomer; wherein the metering, conveying and buffering of the premix components are controlled to be uniform, and the pressure of the buffer is controlled to be the same as the pressure in the polymerization reactor.

[0086] During the first, second, and third polymerizations, additives may be added as needed to control the reaction conditions of the polymerization process or adjust the final product properties. The additives can be designed and adjusted based on the needs of the target polymer and are not specifically limited herein. Preferably, antiscaling agents may be added during the first, second, and / or third polymerizations to prevent problems such as clogging of material transfer pipelines.

[0087] In existing technologies, the main methods for polymerizing polymers include suspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization. Currently, suspension and emulsion polymerization processes have been developed to a considerable degree, achieving large-scale production. However, their cost has reached a critical mass, and their versatility is limited. From a technical perspective, their further development is unlikely, and they will only be used as production processes for specialized polymers. While bulk and solution polymerization still have technical challenges to overcome, they offer significant versatility. Therefore, with the advancement of science and technology, polymer manufacturing processes will gradually shift towards these two methods.

[0088] The polymerization process of the present invention can be selected according to the different forms of the target product, preferably using bulk polymerization or solution polymerization. When the application requirement of the product is in solution form, for example, when used as an adhesive, the first polymerization, the second polymerization and the third polymerization are all solution polymerization. In solution polymerization, due to the use of a solvent, the viscosity of the reaction system is reduced, which is very beneficial for the mixing and heat transfer of materials. Therefore, although it has defects such as increased solvent recovery and treatment processes and solvent pollution to the environment due to the use of a solvent, due to the versatility of solution polymerization, it is easy to achieve large-scale and continuous production. From the perspective of development, solution polymerization still has good development prospects.

[0089] The technical solution of the present invention is to prepare polypropylene by using a fully heterocyclic non-metallocene compound. The method is applicable to solution polymerization and can effectively catalyze propylene homopolymerization, propylene and ethylene copolymerization, and propylene and acrylate monomer copolymerization. The catalyst has high catalytic activity and excellent copolymerization performance. The technical solution of the present invention can be used to polymerize the compound according to the designed molecular structure to obtain a polypropylene product with high added value.

[0090] When the product is required to be in the form of polypropylene powder, for example, as a resin, both the first polymerization and the second polymerization are bulk polymerizations. In bulk polymerization, to easily control the intensity of the reaction, the catalyst suspension can be prepolymerized with propylene monomer to control the intensity of the reaction in bulk polymerization and maintain stable reaction conditions.

[0091] The polymerization reactors for the first polymerization and the second polymerization are connected in parallel; when the first polymer and the second polymer are mixed, the mixing ratio can be adjusted according to the amount of long-chain alkyl groups and polar ester groups introduced into the target product; preferably, the mass ratio of the first polymer to the second polymer is 4 to 9:1; preferably, the molar percentage of the acrylate unit is about 5% to 10%.

[0092] The polymerization process is divided into three steps: a first polymerization, a second polymerization, and a third polymerization. First, according to a designed formulation, a first auxiliary agent, a first olefin monomer, and a catalyst are introduced into a polymerization reactor under polymerization conditions for the first polymerization. The first olefin monomer may be dissolved or dispersed in a solvent before introduction into the polymerization reactor. If the first olefin monomer is a gaseous monomer, the first olefin monomer is introduced directly into the polymerization reactor to dissolve it in the reaction mixture. Prior to mixing, the solvent and the first olefin monomer are typically purified to remove potential catalyst poisons. Simultaneously, according to a designed formulation, a second auxiliary agent, a second olefin monomer, and a catalyst are introduced into the polymerization reactor under polymerization conditions for the second polymerization. The second olefin monomer may be dissolved or dispersed in a solvent before introduction into the polymerization reactor. If the second olefin monomer is a gaseous monomer, the second olefin monomer is introduced directly into the polymerization reactor to dissolve it in the reaction mixture. Prior to mixing, the solvent and the second olefin monomer are typically purified to remove potential catalyst poisons. The resulting first and second polymers are then mixed and copolymerized under polymerization conditions.

[0093] It is recommended that a stirring system be provided in the polymerization reactors for the first polymerization, the second polymerization, and the third polymerization, which may include one or more stirrers. Generally, the stirrer should ensure that the reactants can be operated under the condition of thorough mixing.

[0094] The polymerization reactor is preferably equipped with a control center capable of receiving process control parameters input by engineering and technical personnel and monitoring the polymerization process in real time. During the polymerization process, the control center monitors the polymerization parameters in real time and maintains them within the set conditions. When the polymerization reaction is nearing completion, a chain terminator is added according to the recipe to terminate the reaction.

[0095] The terminator of the present invention is preferably an ethanol solution of hydrochloric acid, wherein the volume concentration of the ethanol solution of hydrochloric acid is preferably 5% to 15%.

[0096] The present invention uses the above-mentioned process design to firstly polymerize and then polymerize the olefin monomers, and then copolymerize the two polymers with different molecular weights. That is, the long blocks of propylene units and the short blocks of acrylate units are alternately incorporated into the main chain of the molecule, thereby rationally controlling the molecular structure of the manufactured polymer and obtaining a high-value-added polypropylene product with designable performance.

[0097] Preferably, the polymerization reactors for the first polymerization, the second polymerization and the third polymerization are loop reactors and / or tank reactors.

[0098] The present invention does not particularly limit the type of solvent, and any common solvent in the technical field can be used. Preferably, the solvent is preferably selected from at least one of n-hexane, n-heptane or toluene, or a mixture of several thereof.

[0099] The technical solution of the present invention aims to produce high-value-added polypropylene with excellent comprehensive performance. The monomers used are defined as follows: the first olefin monomer is selected from propylene; or a mixture of propylene and ethylene, wherein the molar percentage of propylene in the mixture is ≥ 96%. The feed ratio of ethylene to propylene is limited to this ratio because, when liquid-phase bulk polymerization is used, ethylene is a non-condensable gas. High ethylene content in the polymerization reactor may make it difficult to blend with propylene into a uniform phase, and also poses a significant safety risk. The second olefin monomer is selected from at least one of methyl methacrylate, methyl acrylate, or butyl acrylate.

[0100] In the first polymerization, the first olefin monomer is propylene, or a mixture of ethylene and propylene. In this case, ethylene and propylene are copolymerized or propylene is self-polymerized to obtain a slurry containing the first polymer.

[0101] In the second polymerization, the second olefin monomer is preferably at least one of methyl methacrylate, methyl acrylate or butyl acrylate. At this time, the acrylate monomer is homopolymerized under polymerization conditions to obtain a syrup containing the second polymer.

[0102] In the third polymerization, the slurry containing the first polymer and the slurry containing the second polymer are mixed and copolymerized under polymerization conditions. The long blocks of propylene and the short blocks of acrylate are polymerized according to the reactivity ratio of the two polymers under the polymerization conditions to obtain polymer molecules with designable molecular structures. The control center monitors the polymerization process in real time. When the polymerization reaction is nearing completion, the control center instructs the addition of a chain terminator according to the formula quantity and process parameters to terminate the reaction. The chain terminator can be added to the third polymerization reactor through the auxiliary agent inlet to stop the copolymerization reaction. The chain terminator is preferably a coordinated polar compound. In the technical solution of the present invention, an ethanol solution of hydrochloric acid is preferably used to terminate the reaction.

[0103] The catalyst system has high catalytic activity when used for copolymerization of ethylene, propylene and acrylic ester, and can obtain polypropylene with excellent comprehensive performance and high added value.

[0104] Preferably, the reaction temperatures and reaction pressures of the first polymerization, the second polymerization and the third polymerization are the same or different.

[0105] Preferably, the reaction conditions of the first polymerization are: the reaction temperature is 40-70°C, and the reaction pressure is 0.5-3.0 MPa; further, the reaction temperature is preferably 40-45°C, 45-50°C, 50-55°C, 55-60°C, 60-65°C, 65-70°C; the reaction pressure is preferably 0.5-1.0 MPa, 1.0-1.5 MPa, 1.5-2.0 MPa, 2.0-2.5 MPa, 2.5-3.0 MPa.

[0106] Preferably, in the first polymerization, the amount of the main catalyst is 0.002-0.008% of the mass of the first olefin monomer; and the mass ratio of the co-catalyst to the main catalyst is 400-800:1.

[0107] Preferably, the reaction conditions of the second polymerization are: reaction temperature of 60-80°C, and reaction pressure of 1.0-2.0 MPa. Furthermore, the reaction temperature is preferably 60-65°C, 65-70°C, 70-75°C, or 75-80°C; and the reaction pressure is preferably 1.0-1.5 MPa or 1.5-2.0 MPa.

[0108] Preferably, in the second polymerization, the amount of the main catalyst is 0.001 to 0.002% of the mass of the second olefin monomer; and the mass ratio of the co-catalyst to the main catalyst is 700 to 1000:1.

[0109] Preferably, the reaction temperature of the third polymerization is 40-80°C, and the reaction pressure is 0.5-3.0 MPa. Further, the reaction temperature is preferably 40-45°C, 45-50°C, 50-55°C, 55-60°C, 60-65°C, 65-70°C, 70-75°C, 75-80°C; and the reaction pressure is preferably 0.5-1.0 MPa, 1.0-1.5 MPa, 1.5-2.0 MPa, 2.0-2.5 MPa, 2.5-3.0 MPa.

[0110] The specific reaction times of the first polymerization, the second polymerization, and the third polymerization can be designed based on the requirements of the target product and the properties of the olefin monomer and are not specifically limited herein. Preferably, the weight-average molecular weight of the first polymer is ≤100,000; preferably, the weight-average molecular weight of the second polymer is 5,000 to 10,000.

[0111] The polymerization reaction is required to be carried out in an oxygen-free or low-oxygen environment. Preferably, the first polymerization, the second polymerization, and the third polymerization are all carried out in an inert gas atmosphere. The inert gas atmosphere can be nitrogen, or can also be adjusted according to actual conditions.

[0112] The present invention also provides a polypropylene prepared by the above method.

[0113] The molecular structure of the polypropylene can be designed according to process requirements, and the acrylate copolymer component is connected to the main chain of the molecule to modify the performance of the ethylene-propylene copolymer or the propylene polymer. On the one hand, this ensures the effective control of the molecular structure, that is, the molecular structure can be designed. On the other hand, this chemical modification method also avoids the technical deficiencies of the blending modification or reactor blending modification in the prior art, allowing technicians to design polymer products according to target expectations and adjust the structure of the polymer molecules by controlling the process conditions, thereby obtaining high-value-added polypropylene with excellent comprehensive performance.

[0114] The present invention also provides a compatibilizer comprising the polypropylene prepared by the above method, which is applied to a blend of polyacrylate and polypropylene to improve the compatibility thereof.

[0115] The compatibility test is carried out by preparing polypropylene and polyacrylate into a blend in proportion and then observing the phase distribution thereof through an electron microscope.

[0116] The present invention also provides an adhesive comprising the polypropylene prepared by the above method, which is used for bonding polypropylene materials and polar substrates to improve their bonding strength.

[0117] The adhesive strength test is performed by coating the adhesive on the surface of the metal substrate and measuring the peel strength after drying.

[0118] The following examples provide further details. The properties of the propylene copolymers prepared in each example were tested using conventional methods in the art. For the preparation of the procatalyst, see CN201611257991.7. In the following examples, the structure of the procatalyst is defined directly by R1, R2, R3, R4, M, and X.

[0119] Example 1

[0120] The main catalyst adopts the aforementioned chemical structural formula (I), wherein R1=phenyl, R2=phenyl, R3=phenyl, R4=phenyl, M is titanium, and X is Cl; the cocatalyst adopts methylaluminoxane. The first olefin monomer is propylene; the main catalyst is used in an amount of 2 mg, and the cocatalyst is used in an amount of 1.5 g, which are dissolved in 50 ml of the organic solvent toluene; the first polymerization conditions are: nitrogen environment, polymerization temperature of 40°C, polymerization pressure of 3 MPa, and polymerization time of 50 min; the second olefin monomer is butyl acrylate; the main catalyst is used in an amount of 0.2 mg, and the cocatalyst is used in an amount of 0.15 g, which are dissolved in 20 ml of the organic solvent toluene; the second polymerization conditions are: nitrogen environment, polymerization temperature of 70°C, polymerization pressure of 1 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 70°C, polymerization pressure of 1 MPa, and polymerization time of 30 min; the specific operation steps are as follows:

[0121] A. introducing a first olefin monomer into a polymerization reactor at a flow rate of 2 g / min, and adding a catalyst suspension dropwise into the polymerization reactor under continuous stirring, so that the first olefin monomer and the catalyst are contacted in the polymerization reactor under stirring to carry out a first polymerization, thereby obtaining a slurry containing the first polymer;

[0122] B. 15 g of the second olefin monomer and the continuously stirred catalyst suspension are respectively added dropwise into a polymerization reactor, so that the second olefin monomer and the catalyst are contacted in the polymerization reactor under stirring to carry out a second polymerization to obtain a slurry comprising the second polymer;

[0123] C. mixing the slurry comprising the first polymer and the slurry comprising the second polymer to perform a third polymerization;

[0124] D. Terminate the reaction with an ethanol solution containing 10% hydrochloric acid, filter, wash the resulting polymer with ethanol three times, and then vacuum dry at 50° C. for 24 hours before performing a performance test.

[0125] The polypropylene product prepared in the embodiment was tested for performance, wherein the acrylate unit insertion content was determined by 13The results of the measurement by C nuclear magnetic resonance method showed that the molar percentage of the polymerization sequence of the acrylate unit in the copolymer was 5.02%; the weight-average molecular weight of the copolymer was measured by gel chromatography and was 310,000; commercially available polypropylene, commercially available polyacrylate and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend, and the phase distribution thereof was observed by electron microscopy, and it was found that the phase distribution of the blend was uniform and the compatibility was very good; the polypropylene was dissolved and coated on a metal substrate, and the peel strength was measured after drying, and the result was 28.1N / 10mm, showing excellent bonding performance; the copolymer had good toughness, and its impact strength was tested according to ASTM D256 standard, and the room temperature impact strength was 60J / m 2 , low temperature impact strength is 62KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0126] Example 2

[0127] The polymerization method is the same as in Example 1. The main catalyst is of the aforementioned chemical formula (I), wherein R1 = benzyl, R2 = methyl, R3 = benzyl, R4 = benzyl, M is zirconium, and X is Cl; the co-catalyst is trimethylaluminum. The first olefin monomer is propylene; the main catalyst is used in an amount of 4 mg, and the co-catalyst is used in an amount of 2 g, dissolved in 50 ml of the organic solvent toluene; the first polymerization conditions are: nitrogen environment, polymerization temperature of 60°C, polymerization pressure of 2 MPa, and polymerization time of 35 min; the second olefin monomer is methyl acrylate; the main catalyst is used in an amount of 0.3 mg, and the co-catalyst is used in an amount of 0.22 g, dissolved in 20 ml of the organic solvent toluene; the second polymerization conditions are: nitrogen environment, polymerization temperature of 60°C, polymerization pressure of 2 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 60°C, polymerization pressure of 2 MPa, and polymerization time of 30 min.

[0128] The polypropylene product prepared in the embodiment was tested for performance, and the molar percentage of the acrylate unit in the copolymer was 9.52%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 810,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 26.9 N / 10 mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256, and the room temperature impact strength was 60.8 J / m 2, low temperature impact strength is 62.4KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0129] Example 3

[0130] The polymerization method is the same as in Example 1. The main catalyst is of the aforementioned chemical formula (I), wherein R1 = cyclohexyl, R2 = methyl, R3 = cyclohexyl, R4 = cyclohexyl, M is yttrium, and X is Cl; the cocatalyst is triethylaluminum. The first olefin monomer is propylene; the main catalyst is used in an amount of 3 mg, and the cocatalyst is used in an amount of 1.2 g, dissolved in 50 ml of the organic solvent n-hexane; the first polymerization conditions are: nitrogen environment, polymerization temperature of 50°C, polymerization pressure of 2.5 MPa, and polymerization time of 35 min; the second olefin monomer is methyl methacrylate; the main catalyst is used in an amount of 0.3 mg, and the cocatalyst is used in an amount of 0.3 g, dissolved in 20 ml of the organic solvent n-hexane; the second polymerization conditions are: nitrogen environment, polymerization temperature of 80°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 80°C, polymerization pressure of 0.5 MPa, and polymerization time of 30 min.

[0131] The performance of the polypropylene product prepared in the embodiment was tested, and the molar percentage of the acrylate unit in the copolymer was 8.29%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 240,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 28.5N / 10mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256 standard, and the room temperature impact strength was 59.7J / m 2 , low temperature impact strength is 62.3KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0132] Example 4

[0133] The polymerization method is the same as in Example 1. The main catalyst is of the aforementioned chemical formula (I), wherein R1 = phenyl, R2 = phenyl, R3 = phenyl, R4 = cyclopentyl, M is neodymium, and X is Cl; the cocatalyst is tri-n-hexyl aluminum. The first olefin monomer is 96 vol% propylene and 4 vol% ethylene; the main catalyst is used in an amount of 3 mg and the cocatalyst is used in an amount of 2 g, dissolved in 50 ml of the organic solvent heptane; the first polymerization conditions are: nitrogen environment, polymerization temperature of 70°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the second olefin monomer is butyl acrylate; the main catalyst is used in an amount of 0.2 mg and the cocatalyst is used in an amount of 0.18 g, dissolved in 20 ml of the organic solvent heptane; the second polymerization conditions are: nitrogen environment, polymerization temperature of 75°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 50°C, polymerization pressure of 2.5 MPa, and polymerization time of 30 min.

[0134] The polypropylene product prepared in the embodiment was tested for performance, and the molar percentage of the acrylate unit in the copolymer was 7.53%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 420,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 227.4 N / 10 mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256, and the room temperature impact strength was 60.3 J / m 2 , low temperature impact strength is 62.1KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0135] Example 5

[0136] The polymerization method is the same as in Example 1. The main catalyst is the aforementioned chemical formula (I), wherein R1 = cyclopentyl, R2 = methyl, R3 = phenyl, R4 = phenyl, M is rhodium, and X is Cl; the cocatalyst is triisobutylaluminum. The first olefin monomer is propylene; the main catalyst is used in an amount of 3.5 mg, and the cocatalyst is used in an amount of 2 g, dissolved in 50 ml of the organic solvent toluene; the first polymerization conditions are: nitrogen environment, polymerization temperature of 65°C, polymerization pressure of 0.5 MPa, and polymerization time of 40 min; the second olefin monomer is butyl acrylate; the main catalyst is used in an amount of 0.2 mg, and the cocatalyst is used in an amount of 0.18 g, dissolved in 20 ml of the organic solvent toluene; the second polymerization conditions are: nitrogen environment, polymerization temperature of 70°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 40°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min.

[0137] The performance of the polypropylene product prepared in the embodiment was tested, and the molar percentage of the acrylate unit in the copolymer was 5.91%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 640,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 27.6 N / 10 mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256 standard, and the room temperature impact strength was 60.6 J / m 2 , low temperature impact strength is 62.4KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0138] Example 6

[0139] The polymerization method is the same as in Example 1. The main catalyst is of the aforementioned chemical formula (I), wherein R1 = ethyl, R2 = ethyl, R3 = phenyl, R4 = phenyl, M is vanadium, and X is Br; the cocatalyst is triisobutylaluminum. The first olefin monomer is propylene; the main catalyst is used in an amount of 4.5 mg, and the cocatalyst is used in an amount of 3 g, dissolved in 50 ml of the organic solvent toluene; the first polymerization conditions are: nitrogen environment, polymerization temperature of 65°C, polymerization pressure of 1 MPa, and polymerization time of 45 min; the second olefin monomer is butyl acrylate; the main catalyst is used in an amount of 0.2 mg, and the cocatalyst is used in an amount of 0.18 g, dissolved in 20 ml of the organic solvent toluene; the second polymerization conditions are: nitrogen environment, polymerization temperature of 75°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 45°C, polymerization pressure of 3 MPa, and polymerization time of 30 min.

[0140] The performance of the polypropylene product prepared in the embodiment was tested, and the molar percentage of the acrylate unit in the copolymer was 5.30%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 700,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 28.3N / 10mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256 standard, and the room temperature impact strength was 60.9J / m 2 , low temperature impact strength is 62.5KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0141] Example 7

[0142] The polymerization method is the same as that in Example 1. The main catalyst is the aforementioned chemical formula (I), wherein R1 = isopropyl, R2 = isopropyl, R3 = phenyl, R4 = methyl, M is nickel, and X is Cl; the cocatalyst is methylaluminoxane. The first olefin monomer is propylene; the main catalyst is used in an amount of 2.5 mg, and the cocatalyst is used in an amount of 2 g, dissolved in 50 ml of the organic solvent toluene; the first polymerization conditions are: nitrogen environment, polymerization temperature of 45°C, polymerization pressure of 2.5 MPa, and polymerization time of 30 min; the second olefin monomer is butyl acrylate; the main catalyst is used in an amount of 0.2 mg, and the cocatalyst is used in an amount of 0.18 g, dissolved in 20 ml of the organic solvent toluene; the second polymerization conditions are: nitrogen environment, polymerization temperature of 65°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the third polymerization conditions are: nitrogen environment, polymerization temperature of 55°C, polymerization pressure of 2 MPa, and polymerization time of 30 min.

[0143] The polypropylene product prepared in the embodiment was tested for performance, and the molar percentage of the acrylate unit in the copolymer was 7.71%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 250,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 28.7 N / 10 mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256 standard, and the room temperature impact strength was 59.9 J / m 2 , low temperature impact strength is 61.8KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0144] Example 8

[0145] The polymerization method was the same as in Example 1. The main catalyst employed the aforementioned chemical formula (I), wherein R1 = 2,6-dimethylphenyl, R2 = 2,6-dimethylphenyl, R3 = 2,6-dimethylphenyl, R4 = methyl, M is cobalt, and X is Cl; the cocatalyst employed was methylaluminoxane. The first olefin monomer was propylene; 4.8 mg of the main catalyst and 3.8 g of the cocatalyst were dissolved in 50 ml of the organic solvent, toluene; the first polymerization conditions were: nitrogen atmosphere, polymerization temperature of 60°C, polymerization pressure of 2 MPa, and polymerization time of 35 min; the second olefin monomer was butyl acrylate; 0.2 mg of the main catalyst and 0.18 g of the cocatalyst were dissolved in 20 ml of the organic solvent, toluene; the second polymerization conditions were: nitrogen atmosphere, polymerization temperature of 70°C, polymerization pressure of 1.5 MPa, and polymerization time of 30 min; the third polymerization conditions were: nitrogen atmosphere, polymerization temperature of 65°C, polymerization pressure of 2 MPa, and polymerization time of 30 min.

[0146] The performance of the polypropylene product prepared in the embodiment was tested, and the molar percentage of the acrylate unit in the copolymer was 6.72%. The weight-average molecular weight of the copolymer was measured by gel chromatography and was 390,000. Commercially available polypropylene, commercially available polyacrylate, and the copolymer of this embodiment were melt-mixed in a ratio of 45%:45%:10% to prepare a blend. The phase distribution was observed by electron microscopy, and it was found that the blend had a uniform phase distribution and good compatibility. The polypropylene was dissolved and coated on a metal substrate, and its peel strength was measured after drying, and the result was 28.9 N / 10 mm, showing excellent bonding performance. The copolymer had good toughness, and its impact strength was tested according to ASTM D256 standard, and the room temperature impact strength was 60.8 J / m 2 , low temperature impact strength is 62.7KJ / m 2 , and the molecular structure is connected to the main chain of the molecule in the form of a chemical structure, and the migration of groups will not occur over time to affect the adhesion of the polymer.

[0147] Comparative Example 1

[0148] The main catalyst adopts the aforementioned chemical structure (I), wherein R1 = isopropyl, R2 = isopropyl, R3 = phenyl, R4 = methyl, M is nickel, and X is Cl; the co-catalyst is methylaluminoxane. The first olefin monomer is propylene; the second olefin monomer is butyl acrylate. The specific steps are as follows:

[0149] 2.7 mg of the main catalyst and 2.18 g of the co-catalyst were dissolved in 70 ml of the organic solvent toluene; the first olefin monomer was continuously introduced into the polymerization reactor at a flow rate of 2 g / min, and 15 g of the second olefin monomer and the continuously stirred catalyst suspension were respectively added dropwise into the polymerization reactor, and polymerization was carried out for 30 minutes under a nitrogen environment, a temperature of 45°C, and a pressure of 2.5 MPa; then the polymerization temperature was adjusted to 55°C and the polymerization pressure was adjusted to 2 MPa, and polymerization was carried out for 30 minutes.

[0150] The performance of the polypropylene product prepared in the embodiment was tested, and the molar percentage of the acrylic acid ester unit in the copolymer was 0.36%.

[0151] Comparative Example 2

[0152] The main catalyst adopts the aforementioned chemical structure, wherein R1 = isopropyl, R2 = isopropyl, R3 = phenyl, R4 = methyl, M is nickel, and X is Cl; the co-catalyst is methylaluminoxane. The first olefin monomer is propylene; the second olefin monomer is butyl acrylate. The specific steps are as follows:

[0153] 2.7 mg of the main catalyst and 2.18 g of the co-catalyst were dissolved in 70 ml of the organic solvent toluene; the first olefin monomer was continuously introduced into the polymerization reactor at a flow rate of 2 g / min, and 15 g of the second olefin monomer and the continuously stirred catalyst suspension were respectively added dropwise into the polymerization reactor, and polymerization was carried out in a nitrogen environment, a temperature of 65°C, and a pressure of 1.5 MPa for 30 minutes; then the polymerization temperature was adjusted to 55°C and the polymerization pressure was adjusted to 2 MPa, and polymerization was carried out for 30 minutes.

[0154] The performance of the polypropylene product prepared in the embodiment was tested. The performance of the copolymer product was uncontrolled. Some samples contained long blocks of acrylate, while some samples did not contain acrylate units.

[0155] Comparative Example 3

[0156] The main catalyst adopts the aforementioned chemical structure, wherein R1 = isopropyl, R2 = isopropyl, R3 = phenyl, R4 = methyl, M is nickel, and X is Cl; the co-catalyst is methylaluminoxane. The first olefin monomer is propylene; the second olefin monomer is butyl acrylate. The specific steps are as follows:

[0157] 2.7 mg of the main catalyst and 2.18 g of the co-catalyst were dissolved in 70 ml of the organic solvent toluene; the first olefin monomer was continuously introduced into the polymerization reactor at a flow rate of 2 g / min, and 15 g of the second olefin monomer and the continuously stirred catalyst suspension were respectively added dropwise into the polymerization reactor, and polymerization was carried out for 60 minutes under a nitrogen environment, a temperature of 55°C, and a pressure of 2 MPa.

[0158] The above-described embodiments 1 to 8 are merely specific examples of implementing the technical solutions of the present invention. Through the above-described embodiments, the present invention utilizes propylene or propylene containing a small amount of ethylene as the first olefin monomer and an acrylate monomer as the comonomer for copolymerization under the polymerization process conditions proposed by the present invention. By controlling the process conditions of each polymerization reaction stage so that propylene and acrylate are polymerized into polymers of a certain air volume, and then the two polymers are copolymerized, the entire polymerization process is carried out according to the process design, thereby controlling the molecular structure of the polymer. The content of the copolymer component in the polypropylene prepared by the technical solution of the present invention is controlled and can be adjusted according to the needs of the target product. Furthermore, the copolymer component is connected to the molecular chain of the ethylene or propylene polymer in the form of a molecular chain structure, resulting in a stable structure. The composition of the molecular chain does not undergo phase migration over time, thereby obtaining a high-value-added polypropylene with excellent comprehensive performance. The properties of the polypropylene can be maintained for a long time, thus having excellent effects and application value. At the same time, the technical solution of the present invention controls the catalyst feeding method so that the catalyst components introduced into the polymerization reactor are uniform and the temperature and pressure are consistent with those of the polymerization reactor, thereby minimizing the influence of the catalyst feeding process on the polymerization reaction, controlling the process conditions of the polymerization reaction, and producing high-performance polypropylene with a designable molecular structure, thereby improving the uniformity and comprehensive performance of the product molecular structure, and avoiding blockage of the feed pipeline, thereby improving production efficiency.

[0159] Comparative Examples 1, 2, and 3 above use the same feed amounts and reaction times as Example 7, only combining the first and second polymerization processes, and using the process conditions of the first and second polymerizations, respectively. After polymerization for the set process time, the reaction conditions are switched to the third polymerization process for copolymerization; alternatively, the third polymerization process is used throughout for copolymerization. The results of the polypropylene obtained show that when propylene and acrylate are fed and copolymerized under the same conditions, the first polymerization condition is more suitable for propylene polymerization, and the resulting polymer has a low content of acrylate blocks; while the second polymerization condition is more suitable for acrylate polymerization, some of the resulting polymer molecules contain long acrylate blocks, while some do not contain acrylate units, resulting in an unstable molecular structure and difficulty in obtaining a product with stable and controlled performance; while the third polymerization condition is more suitable for the copolymerization of the two units, and some segments of the resulting polymer molecular chain show random copolymerization, while some segments show long propylene blocks, resulting in an uneven distribution of the molecular structure of the polymer and difficulty in achieving stable and controlled performance. It can be seen that the technical solution of the present invention is to self-polymerize the first olefin monomer and the second olefin monomer into a polymer of a certain molecular weight under respective suitable polymerization conditions, and then copolymerize the two polymers under suitable copolymerization conditions, so that the long blocks of propylene and the short blocks of acrylate are evenly distributed in the obtained polypropylene molecular chain, thereby controlling the molecular chain structure of the polymer and stabilizing the performance of the product.

[0160] Furthermore, the chain and sequence structure of the copolymer directly influences its various properties when used as a polymer material, such as mechanical, dielectric, and thermal properties, and also directly impacts the selection of molding and processing conditions. The present invention obtains molecular structural information by measuring the chain end length and structure of the polymer using gel chromatography and identifying the characteristic "fingerprint" produced by changes in the energy levels of the atomic nuclear magnetic moments within the molecule using nuclear magnetic resonance. The obtained information is then used to comprehensively analyze and infer the sequence structure of the polymer chain. By comparative analysis of the molecular chains of Example 7 and Comparative Examples 1, 2 and 3, it can be determined that the molecular chain structure of the polymer prepared by the technical solution of the present invention has a stable and controlled order in which the molecular chain is connected. When the letter A represents the first olefin unit and the letter B represents the second olefin unit, its molecular chain structure basically exhibits a block structure, which belongs to a special gradient sequence structure, schematically represented by AAAAAAAABBBAAAAAAABBBB...; while in the comparative example, the technical solution of the present invention is not adopted to alternately feed the comonomers. After several monomers enter the reaction system together, a structurally unstable polymer is randomly generated mainly by the difference in the competitive polymerization rates of several olefin monomers. Its molecular structure is not controlled and the performance of the polymer is also unstable.

[0161] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing acrylate-modified polypropylene, characterized in that: The following steps are involved: 1) contacting a first olefin monomer with a catalyst to perform a first polymerization to obtain a slurry containing a first polymer; the first olefin monomer is a mixture of propylene and ethylene, or one of propylene, wherein the molar percentage of propylene in the mixture is ≥96%; 2) contacting a second olefin monomer with a catalyst to perform a second polymerization to obtain a slurry containing a second polymer; wherein the second olefin monomer is selected from an alkyl acrylate having a carbon chain length of C1 to C18; Wherein, the catalyst includes a main catalyst and a co-catalyst, and the main catalyst is shown in the following formula: In Formula I, R1 and R2 are independently selected from one of a C1-C20 alkyl group, a C3-C20 cycloalkyl group, and a C6-C20 aryl group; R3 and R4 are the same or different and are independently selected from one of a hydrogen atom, a C1-C20 alkyl group, a C3-C20 cycloalkyl group, and a C6-C20 aryl group; X is selected from Cl, Br, methyl, or ethyl; M is selected from titanium, zirconium, hafnium, vanadium, rhodium, iron, nickel, cobalt, neodymium, palladium, or yttrium; The co-catalyst includes an organometallic aluminum compound; The ratio of the co-catalyst to the main catalyst is 400 to 1000:1 by mass; 3) mixing the slurry containing the first polymer and the slurry containing the second polymer to perform a third polymerization; 4) Add a chain terminator to terminate the reaction to obtain acrylate-modified polypropylene.

2. The preparation method according to claim 1, characterized in that The co-catalyst is selected from at least one of trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum and methylaluminoxane.

3. The preparation method according to claim 1, characterized in that In the first polymerization, the amount of the main catalyst used is 0.002 to 0.008% of the mass of the first olefin monomer; the ratio of the co-catalyst to the main catalyst is 400 to 800:

1.

4. The preparation method according to claim 1, characterized in that The reaction temperature of the first polymerization is 40-70° C., and the reaction pressure is 0.5-3.0 MPa.

5. The preparation method according to claim 1, characterized in that The weight average molecular weight of the first polymer is ≤100,000.

6. The preparation method according to claim 1, characterized in that The second olefin monomer is selected from at least one of methyl methacrylate, methyl acrylate and butyl acrylate.

7. The preparation method according to claim 1, characterized in that In the second polymerization, the amount of the main catalyst used is 0.001 to 0.002% by mass of the second olefin monomer; and the ratio of the co-catalyst to the main catalyst is 700 to 1000:

1.

8. The preparation method according to claim 1, characterized in that The reaction temperature of the second polymerization is 60-80° C., and the reaction pressure is 1.0-2.0 MPa.

9. The preparation method according to claim 1, characterized in that The weight average molecular weight of the second polymer is 5,000 to 10,000.

10. The preparation method according to claim 1, characterized in that The mass ratio of the first polymer to the second polymer is 4 to 9:

1.

11. The preparation method according to claim 1, characterized in that The polymerization reactors for the first polymerization, the second polymerization and the third polymerization are loop reactors and / or tank reactors.

12. The preparation method according to claim 1, characterized in that In step 1) and step 2), the catalyst feeding comprises the following steps: 11) uniformly mixing the catalyst and the solvent to obtain a catalyst premix solution; 12) The catalyst premix is ​​sequentially metered, conveyed, and buffered before being introduced into a polymerization reactor; wherein the components of the premix are controlled to be uniform during the metering, conveying, and buffering processes, and the pressure in the buffer tank used in the buffering process is controlled to be the same as the pressure in the polymerization reactor.

13. The preparation method according to claim 12, characterized in that The solvent is selected from at least one of n-hexane, n-heptane and toluene.

14. The preparation method according to claim 1, characterized in that An anti-scaling agent is added during the first polymerization, the second polymerization and / or the third polymerization.

15. The preparation method according to claim 1, characterized in that The reaction temperature of the third polymerization is 40-80° C., and the reaction pressure is 0.5-3.0 MPa.

16. The preparation method according to claim 1, characterized in that The first polymerization, the second polymerization and the third polymerization are all carried out under an inert gas atmosphere.

17. The preparation method according to claim 1, characterized in that The chain terminator is an ethanol solution of hydrochloric acid.

18. Acrylate-modified polypropylene prepared by the method according to any one of claims 1 to 17.

19. A compatibilizer, characterized in that: The acrylate-modified polypropylene according to claim 18 is used in a blend of polyacrylate and polypropylene to improve the compatibility thereof.

20. An adhesive, characterized in that: The acrylate-modified polypropylene according to claim 18 is used for bonding polypropylene materials to polar substrates to improve their bonding strength.

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