High-gloss polypropylene and preparation method thereof

Abstract

The invention provides high-gloss polypropylene and a preparation method thereof, and the preparation method comprises the following steps: (1) adding a main catalyst, a cocatalyst, an external electron donor and an anti-reflection agent into a reactor, then introducing ethylene and propylene, and carrying out a polymerization reaction to obtain a reaction product; and (2) carrying out post-treatment on the reaction product obtained in the step (1), then adding an auxiliary agent, and carrying out extrusion granulation to obtain the high-gloss polypropylene, the anti-reflection agent has an aromatic triamide structure or a cyclohexane triamide structure. According to the preparation method provided by the invention, the selected anti-reflection agent can be directly blended with a catalytic system, is an inert substance relative to the catalytic system and does not interfere with polymerization of propylene into polypropylene, and meanwhile, molecular-level dispersion of the anti-reflection agent can be realized by utilizing a polymerization process, so that only 0.01-0.05% of the anti-reflection agent is needed, and the anti-reflection effect is good. The effect of effectively improving the transparency and the surface glossiness of the polypropylene can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical processes and relates to high-gloss polypropylene and a preparation method thereof. Background Art

[0002] Polypropylene is a typical partially crystalline thermoplastic resin. Its favorable performance-price ratio dictates its wide range of applications. Transparent, high-gloss polypropylene is a key product, widely used in daily chemical products, medical devices, stationery, and food packaging, and currently enjoys significant domestic demand. There are two common methods for increasing the transparency and surface gloss of polypropylene products: one is to adjust the polymerization process by copolymerizing polyethylene and / or butene-1 to reduce the crystallinity of polypropylene, thereby achieving visible light transmission and parallel reflection; the other is to blend a clarifier (i.e., a transmittance enhancer) outside the reactor to achieve crystal refinement through heterogeneous nucleation.

[0003] Based on existing implementation methods, transparent, high-gloss polypropylene is currently produced through homopolymerization or random polypropylene special materials through gas phase, bulk, or gas phase and bulk combined processes. A single agent or premix containing a transparency enhancer is blended into the polymerized powder or pellets to achieve this. Some petrochemical plants use this premix directly in the pelletizing process to produce transparent special materials, while modification plants use high-speed mixers and screw extruders for secondary modification. Modification production usually also adds other functional additives such as color. All of these methods require a relatively large amount of the transparent agent component, ranging from 1‰ to 5‰ (by weight).

[0004] CN102127263A discloses a method for modifying in-vehicle alloyed polypropylene materials for automotive applications. The method involves mixing surface-activated in-vehicle alloyed polypropylene, a coupling agent, an anti-light aging agent, an antioxidant, and polyethylene wax in a high-speed mixer. The mixture is then melt-extruded through an extruder, extruded through a screw mixer, pelletized, and dried to obtain the finished product. This method utilizes polymerized polypropylene, which is then reactivated and then modified by blending functional additives outside the in-vehicle mixer.

[0005] CN102040769A discloses a clay-reinforced polypropylene in-reactor alloy and its preparation method. The in-reactor alloy comprises clay, homopolymer polypropylene resin, and ethylene-α-olefin random copolymer. The preparation method utilizes the catalyst-polymer particle morphology replication effect to in-situ catalyze the copolymerization reaction of propylene monomer and comonomer on a clay-supported transition metal catalyst whose particles have a spherical apparent morphology. The nanoclay-reinforced polypropylene and copolymer resin prepared by this method have spherical particles, which not only achieve the goals of the polymer being non-stick to the reactor, easy to flow, and easy to transport, but also the clay flakes are evenly dispersed in the resin matrix in an exfoliated form. The invention uses clay as a carrier for one of the catalyst components to prepare a clay-containing catalyst, which is then applied to propylene polymerization. Due to the effect of the catalyst activity, the weight proportion of the clay component in the final polypropylene is only 1 / 100,000 to 1 / 50,000, and the clay morphology must be adapted to the active center. Therefore, its ability to reinforce polypropylene in the in-reactor is limited and cannot achieve an anti-transmittance effect.

[0006] CN1330088A discloses a method for preparing highly crystalline polypropylene in an autoclave. The method is characterized by comprising a composite nucleating agent containing at least one organic nucleating agent, which is a heterocyclic organic metal salt compound with a melting point above 300°C. The composite nucleating agent may contain one or more inorganic nucleating agents, each of which is a solid ultrafine powder, such as bentonite, talc, calcium carbonate, or silica. This method primarily utilizes inorganic particles, with some organic particles blended in the autoclave, but the type and proportion of these organic particles are not specified.

[0007] CN102838701A discloses a propylene multiphase copolymerization system, polymerization method, and product. This propylene multiphase copolymerization system effectively inhibits the mutual fusion and aggregation of the ethylene-propylene random copolymer dispersed phase in a polypropylene / ethylene-propylene random copolymer reactor alloy. The propylene multiphase copolymerization system provided in this invention, in addition to conventional components such as a propylene catalyst, co-catalyst, and external electron donor, includes a key component, an aliphatic or aromatic symmetrical diene monomer, which stabilizes the ethylene-propylene copolymer dispersed phase. This component inhibits the agglomeration of the ethylene-propylene rubber phase components formed in situ within the reactor, but does not contribute to heterogeneous nucleation, which can enhance rigidity and transparency.

[0008] CN103724464A proposes a method for modifying and preparing a nucleating agent for high-performance polypropylene. Without changing the polymerization process conditions, the nucleating agent is modified or a special feeding method is used to shield components that cause catalyst poisoning and inactivation, allowing the effective nucleating agent components to be released as completely as possible during the reaction nucleation polymerization process. The functional groups of the modified nucleating agent do not adversely affect the activity of the main catalyst, do not react with the co-catalyst and electron donor, and the catalytic activity is substantially unchanged. Furthermore, the modified polypropylene exhibits excellent performance, with significant in-reactor nucleation, and can produce polypropylene with high overall performance. However, the invention does not clarify the nucleating agent modification method, nor does it describe the structure of the modified nucleating agent, nor does it elaborate on the improved product performance after blending the modified nucleating agent.

[0009] Therefore, it is desired in the art to develop a method for preparing polypropylene with a simple process, and to enable the prepared polypropylene to have high gloss while using a small amount of a transmittance enhancer. Summary of the Invention

[0010] In response to the shortcomings of the prior art, the present invention aims to provide high-gloss polypropylene and a method for preparing the same. Using the transmittance enhancer defined in the present invention and its application method, high-gloss polypropylene can be generated in situ. The transmittance enhancer defined in the present invention is directly blended with the catalytic system in the same anhydrous and oxygen-free environment as the catalytic system and then injected into the catalyst treatment unit of the polymerization process, thereby directly initiating ethylene-propylene copolymerization and directly preparing a polymer product containing the molecularly dispersed transmittance enhancer in situ. While maintaining stable operation of the device, high-gloss copolymerized polypropylene is directly obtained in a one-step process.

[0011] Conventional transmittance enhancers contain groups such as hydroxyl groups that are harmful to catalysts. Direct application in the kettle will poison the catalyst activity and prevent the formation of polypropylene. However, due to the limitations of equipment precision and processing efficiency, it is impossible to achieve molecular-level blending when blending outside the kettle. The agglomerated transmittance enhancer cannot maximize the heterogeneous nucleation effect. At the same time, the group structure of conventional transmittance enhancers shows that the organic component will be affected by static electricity when blended outside the kettle. Therefore, conventional transmittance enhancers can only rely on increasing the dosage to achieve the transmittance and brightening effect. The dosage is generally 1‰-5‰ (additive / polypropylene, weight ratio), while the dosage of conventional antioxidant systems is only 0.5‰-2‰ (additive / polypropylene, weight ratio).

[0012] The present invention utilizes a conventional ZN catalyst system. The permeability enhancer is directly blended with the catalyst system and then injected into the catalyst treatment unit of the polymerization process. Ethylene or 1-butene and propylene copolymerize according to the process flow, resulting in the direct in-situ production of high-gloss, transparent copolymerized polypropylene. The permeability enhancer is directly applied to the reactor, concurrently with polypropylene production. The formation of polypropylene particles is accompanied by the dispersion of the permeability enhancer, significantly improving its dispersion efficiency, achieving molecular-level dispersion while significantly reducing the amount of permeability enhancer used.

[0013] To achieve this object, the present invention adopts the following technical solutions:

[0014] In a first aspect, the present invention provides a method for preparing high-gloss polypropylene, the preparation method comprising:

[0015] (1) directly mixing the main catalyst, co-catalyst, external electron donor and permeability enhancer into a reactor, and then introducing ethylene and propylene gases in a certain proportion to carry out polymerization reaction to obtain a reaction product;

[0016] (2) the reaction product obtained in step (1) is post-treated, and then an auxiliary agent is added and extruded into granules to obtain the high-gloss polypropylene;

[0017] The transmittance enhancer has an aromatic triamide structure or a cyclohexane triamide structure.

[0018] In the preparation method provided by the present invention, the selected transmittance enhancer can be directly blended with the catalytic system. The transmittance enhancer is an inert substance relative to the catalytic system and will not interfere with the polymerization of propylene into polypropylene. At the same time, the polymerization process can be used to achieve molecular-level dispersion of the transmittance enhancer, thereby achieving the effect of effectively improving the transparency and surface gloss of polypropylene with only 0.1‰-0.5‰ (adjuvant / polypropylene, weight ratio).

[0019] Preferably, the permeability enhancer has a structure as shown in the following formula I:

[0020]

[0021] wherein R1, R2, and R3 each independently represent a C1-C18 alkyl group, a C3-C18 alkenyl group, a C5-C10 cycloalkyl group, a C5-C10 cycloalkenyl group, a C5-C10 cycloalkyl group substituted with up to three C1-C6 alkyl groups, or a C5-C10 cycloalkenyl group substituted with up to three C1-C6 alkyl groups.

[0022] Moreover, the benzene ring at the center of the skeleton of the above formula I is hydrogenated to become a saturated cyclohexane, and the corresponding structure still has the same effect, that is, the above-mentioned permeability enhancer has a cyclohexane triamide structure.

[0023] In the present invention, C1-C18 alkyl can be, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, n-heptyl, isoheptyl, 1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1,1,3-trimethylhexyl, 1,1,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. Preferred examples are ethyl, isopropyl, butyl, tert-butyl, etc.

[0024] Examples of the C3-C18 alkenyl group include allyl, 2-methallyl, butenyl, pentenyl, hexenyl and norbornenyl, etc. Preferred examples are allyl and norbornenyl.

[0025] Examples of the C5-C10 cycloalkyl group include cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl, and preferably cyclohexyl, cycloheptyl and cyclooctyl.

[0026] The C5-C10 cycloalkenyl group may be, for example, a cyclohexenyl group.

[0027] Examples of the C5-C10 cycloalkyl group substituted with up to 3 (e.g., 1, 2, 3) C1-C6 (e.g., C1, C2, C3, C4, C5, C6) alkyl groups include 3-methylcyclohexyl and 2,3-dimethylcyclohexyl.

[0028] The C5-C10 cycloalkenyl group substituted by up to 3 (e.g., 1, 2, 3) C1-C6 (e.g., C1, C2, C3, C4, C5, C6) alkyl groups may be, for example, a methylcyclohexenyl group.

[0029] Preferably, the purity of the permeability enhancer represented by formula I is ≥99%.

[0030] Preferably, based on 100% of the mass of the final product high gloss polypropylene, the amount of the transmittance enhancer is 0.1‰-0.5‰, for example, 0.1‰, 0.2‰, 0.3‰, 0.4‰, 0.5‰, etc.

[0031] Preferably, the main catalyst comprises a ZN catalyst.

[0032] In the present invention, the permeability enhancer is suitable for a ZN catalyst system comprising a conventional ZN catalyst, an organoaluminum compound and an organosilane compound. Suitable polymerization processes include propylene bulk polymerization process and gas phase polymerization process, as well as a combination thereof.

[0033] Preferably, the ZN catalyst includes but is not limited to any one of the TK series, CS series, N series, DQ series, SAL series, and BCZ series.

[0034] Preferably, the co-catalyst comprises an organoaluminum compound.

[0035] Preferably, the co-catalyst includes but is not limited to any one or a combination of at least two of trimethylaluminum, triethylaluminum, triisobutylaluminum, and diethylaluminum monochloride, preferably triethylaluminum.

[0036] Preferably, the external electron donor comprises an organosilane compound.

[0037] Preferably, the external electron donor includes but is not limited to any one of isobutyltriethoxysilane, diisobutyldimethoxysilane, dicyclopentyldimethoxysilane, diphenyldimethoxysilane, methylcyclohexyldimethoxysilane, diisopropyldimethoxysilane, tetraethoxysilane, isopropylisobutyldimethoxysilane, and norbornenetrimethoxysilane, or a combination of at least two thereof.

[0038] Preferably, in the system consisting of the main catalyst, co-catalyst and external electron donor, the molar ratio of Al, Si and Ti is 50-150:2-10:1, 50-150 can be, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, etc., and 2-10 can be, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0039] Preferably, in step (1), the mass ratio of the amount of propylene introduced to the main catalyst is 5000 to 50000:1, for example, 5000:1, 8000:1, 10000:1, 15000:1, 20000:1, 25000:1, 30000:1, 35000:1, 40000:1, 45000:1, 50000:1, etc.

[0040] Preferably, based on 100% mass of the final product high gloss polypropylene, the amount of ethylene is 0.1%-5.0%, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, etc.

[0041] Preferably, the polymerization reaction process in step (1) includes any one of a single-pot process, a process of at least two pots (such as two pots, three pots or four pots) in series or in parallel.

[0042] Preferably, the process of the polymerization reaction in step (1) includes any one of the Hypol process, ST process, Unipol process, and Spheripol process; the reactor used can be a single liquid phase or gas phase reactor, or a combination of multiple reactors.

[0043] Preferably, the reactor comprises a polymerization kettle.

[0044] Preferably, the polymerization reaction time in step (1) is 40-200 min, for example, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, etc.

[0045] Preferably, the post-processing includes degassing and screening.

[0046] Preferably, the auxiliary agent includes an antioxidant.

[0047] Preferably, the antioxidant includes a primary antioxidant and / or a secondary antioxidant.

[0048] Preferably, the primary antioxidant includes but is not limited to any one of antioxidant 264 (BHT), antioxidant 1010, antioxidant 3114, antioxidant 1076, and antioxidant 330, or a combination of at least two thereof.

[0049] Preferably, the auxiliary antioxidant includes but is not limited to phosphite antioxidants, such as antioxidant 168, any one of alkyl phosphites (624, 626, etc.) or a combination of at least two thereof.

[0050] Preferably, based on 100% of the mass of the final product high gloss polypropylene, the added amount of the antioxidant is 0.5‰-2‰, for example, 0.5‰, 0.8‰, 1‰, 1.2‰, 1.4‰, 1.6‰, 1.8‰, 2‰, etc.

[0051] Preferably, the auxiliary agent further comprises a halogen absorber and / or an antistatic agent.

[0052] The process applicable to the present invention is the process used for conventional transparent polypropylene. The permeability enhancer, which is conventionally added during the extrusion granulation stage, is moved to the catalyst system configuration unit. At the same time, the amount of permeability enhancer used can be significantly reduced, with the amount used being only 0.1-0.5‰ (by weight) relative to the polymer product. The same amount of the additive is used in the extrusion granulation unit to achieve the production of special transparent polypropylene materials.

[0053] The preparation method provided by the present invention is applicable to existing polypropylene production processes, including single or multi-reactor series or parallel processes. The polymerization units include, but are not limited to, vertical reactors, fluidized beds, loop polymerization units, and plug flow reactors. Conventional antioxidant system additives can be directly added to the polymerized product to produce specialized materials, eliminating the need for additional specialized additives such as permeability enhancers.

[0054] In a second aspect, the present invention provides a high-gloss polypropylene, which is prepared using the preparation method described in the first aspect.

[0055] Preferably, the high gloss polypropylene has a 60° gloss of 104%-117%.

[0056] Compared with the prior art, the present invention has at least the following beneficial effects:

[0057] Compared with the existing production polypropylene transparent special material, the permeability enhancer consumption described in the present invention is significantly reduced compared with the existing second generation or third generation sorbitol type permeability enhancer consumption, and it is an inert substance relative to the ZN catalyst system, can be in the case of normally initiating ethylene propylene copolymerization without affecting the catalyst system, after the configuration unit is pre-treated, it is injected into the reactor together with the catalyst, and it is accompanied by the generation of polypropylene particles, while utilizing the mechanical or chemical energy of the polymerization kettle to achieve uniform dispersion, and its dispersed uniformity is more uniform than granulation unit. The using method of the permeability enhancer in the present invention does not increase extra energy consumption, and as the inert substance of the catalyst system, additional processing is not yet needed in the catalyst configuration unit, and its dispersion effect relies on subsequent polymerization process. The production of high-gloss polypropylene special material can be more efficiently realized with the permeability enhancer provided by the present invention, and the obtained polypropylene also has higher transparency. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0059] The following examples or comparative examples are described as follows:

[0060] 1. Melt flow rate (MFR): test method (standard) GB / T3862, unit is g / 10min.

[0061] 2. Ethylene content: Infrared spectroscopy, test method (standard) GB / T 6040.

[0062] 3. Haze and 60° gloss, test method, GB / T 2410.

[0063] 4. For ease of comparison, in the following examples and comparative examples, the main ZN catalysts used were ND2, SAL-DL, and BCZ-208; the cocatalysts used were triethylaluminum; and the external electron donors (donors) used were methylcyclohexyldimethoxysilane (Donor-C) and diisopropyldimethoxysilane (DIP). However, it should be noted that the present invention is not limited to the above polymerization systems.

[0064] 5. In the following examples, Example 1 selects the Hypol polymerization process, which is the longest process among the existing large-scale polypropylene production processes; Example 2 selects the ST process, which is the mainstream process for producing random copolymer products; Example 3 is the Unipol process, which is a gas phase process.

[0065] 6. In the following examples, the permeability enhancer of the present invention was applied in a kettle in each example. The permeability enhancer used in the comparative example was a conventional sorbitol-based additive and a new organic compound NX8000 launched by Milliken & Company, which were blended outside the kettle in an amount of 3‰ (permeability enhancer / final product polypropylene, weight ratio).

[0066] 7. In the following examples, the selected transmittance enhancers are s-triisopropylamide benzene (referred to as transmittance enhancer A), s-tri-tert-butylamide benzene (referred to as transmittance enhancer B), s-trinorbornenylamide benzene (referred to as transmittance enhancer C), and s-tricyclohexenylamide benzene (referred to as transmittance enhancer D). However, it should be noted that the present invention is not limited to the above experimental examples, and the specific scope should be subject to the claims.

[0067] 8. In the following examples and comparative examples, in the system consisting of the main catalyst, co-catalyst and external electron donor, the molar ratio of Al, Si and Ti was 100:5:1; the mass ratio of the amount of propylene fed to the main catalyst was 20000:1; the antioxidants were a combination of antioxidant 1010 and antioxidant 168 (their mass ratio was 1:1), and the amount of antioxidant added was 1‰.

[0068] Example 1

[0069] The Hypol process employs a series-connected structure of two liquid-phase reactors and two fluidized beds. A primary catalyst, a co-catalyst, and an external electron donor (donor) are mixed with a predetermined amount of the permeability enhancer described herein and added to a catalyst configuration unit. Propylene and ethylene gases are introduced for random copolymerization (polymerization temperature: 70°C; polymerization time: 90 minutes). The polymerization product is degassed, sieved, and then extruded and granulated with an antioxidant to yield the desired product.

[0070] The dosage of the permeation enhancer in the kettle in this embodiment is 0.1‰, 0.3‰ and 0.5‰ respectively (permeation enhancer / final product polypropylene, weight ratio). The target products are low MFR blister molding materials and high MFR injection molding materials.

[0071] It should be noted that Example 1 of the present invention specifically includes Example 1-1-1 to Example 1-1-3, Example 1-2-1 to Example 1-2-3, and Example 1-3-1 to Example 1-3-3.

[0072] The corresponding comparative example 1 includes comparative example 1-1 to comparative example 1-6.

[0073] Some of the raw materials and amounts used in Example 1 and Comparative Example 1, as well as the test results, are shown in Table 1.

[0074] Example 2

[0075] The ST process employs a series-connected structure consisting of two liquid-phase loops and two fluidized beds. A primary catalyst, a co-catalyst, and an external electron donor (donor) are mixed with a predetermined amount of the present invention's permeability enhancer and added to a dedicated catalyst-equipped loop. The mixture is then injected into a loop polymerization reactor, where propylene and ethylene gases are introduced for random copolymerization (at a temperature of 70°C and a polymerization time of 90 minutes). The polymerization product is then degassed, screened, and subjected to extrusion granulation after addition of an antioxidant system to yield the desired product.

[0076] The dosage of the permeation enhancer in the kettle in this embodiment is 0.1‰, 0.3‰ and 0.5‰ respectively (permeation enhancer / final product polypropylene, weight ratio). The target products are low MFR blister molding materials and high MFR injection molding materials.

[0077] Similar to Example 1, Example 2 and the corresponding Comparative Example 2 are also a series of examples, as shown in Table 2.

[0078] Example 3

[0079] The Unipol process employs two fluidized beds in series. A primary catalyst, a co-catalyst, and an external electron donor (donor) are mixed with a predetermined amount of the permeability enhancer described herein and added to a dedicated catalyst preparation kettle. The mixture is then injected into a fluidized bed reactor, where propylene and ethylene gases are introduced for random copolymerization (polymerization temperature: 70°C, polymerization time: 90 minutes). The polymerization product is then degassed, sieved, and subjected to an antioxidant treatment before extrusion and granulation to yield the desired product.

[0080] The dosage of the permeation enhancer in the kettle in this embodiment is 0.1‰, 0.3‰ and 0.5‰ respectively (permeation enhancer / final product polypropylene, weight ratio). The target products are low MFR blister molding materials and high MFR injection molding materials.

[0081] Similar to Example 1, Example 3 and the corresponding Comparative Example 3 are also a series of examples, as shown in Table 3.

[0082] Comparative Examples 1-3

[0083] In the three polymerization processes described above, the catalytic system is configured according to conventional requirements and then injected into the polymerization reaction unit for ethylene-propylene random copolymerization (polymerization temperature is 70°C, polymerization time is 90 minutes). After the polymer powder is degassed and dried, a composite auxiliary agent containing a sorbitol-type permeability enhancer or NX8000 permeability enhancer and an antioxidant system are added in the extrusion granulation unit to prepare the target product.

[0084] Table 1 Summary of relevant information of Example 1 and Comparative Example 1

[0085]

[0086]

[0087] Table 2 Summary of relevant information of Example 2 and Comparative Example 2

[0088]

[0089] Table 3 Summary of relevant information of Example 3 and Comparative Example 3

[0090]

[0091]

[0092] It can be seen from Tables 1 to 3 that, compared with the comparative example, in the preparation method provided by the embodiment of the present invention, when the amount of transmittance enhancer used is small (the amount used is only 1 / 30 to 1 / 6 of the amount used of the conventional transmittance enhancer), the transparency and surface gloss of polypropylene can be effectively improved.

[0093] The applicant declares that while the above-described embodiments illustrate the high-gloss polypropylene and its preparation method, the present invention is not limited to these embodiments. This does not necessarily mean that the present invention must rely on these embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing high gloss polypropylene, characterized in that: The preparation method comprises: (1) adding a main catalyst, a co-catalyst, an external electron donor and a permeability enhancer into a reactor, and then introducing ethylene and propylene to carry out a polymerization reaction to obtain a reaction product; (2) the reaction product obtained in step (1) is post-treated, and then an auxiliary agent is added and extruded into granules to obtain the high-gloss polypropylene; The transmittance enhancer has an aromatic triamide structure or a cyclohexane triamide structure.

2. The preparation method according to claim 1, characterized in that The permeability enhancer has a structure as shown in the following formula I: wherein R1, R2, and R3 each independently represent a C1-C18 alkyl group, a C3-C18 alkenyl group, a C5-C10 cycloalkyl group, a C5-C10 cycloalkenyl group, a C5-C10 cycloalkyl group substituted with up to three C1-C6 alkyl groups, or a C5-C10 cycloalkenyl group substituted with up to three C1-C6 alkyl groups.

3. The preparation method according to claim 1 or 2, characterized in that Based on the mass of the final product high gloss polypropylene being 100%, the dosage of the transmittance enhancer is 0.1‰-0.5‰.

4. The preparation method according to any one of claims 1 to 3, characterized in that The main catalyst includes a ZN catalyst; Preferably, the ZN catalyst includes any one of TK series, CS series, N series, DQ series, SAL series, and BCZ series.

5. The preparation method according to any one of claims 1 to 4, characterized in that The co-catalyst includes an organoaluminum compound; Preferably, the co-catalyst includes any one of trimethylaluminum, triethylaluminum, triisobutylaluminum, and diethylaluminum chloride, or a combination of at least two thereof, preferably triethylaluminum.

6. The preparation method according to any one of claims 1 to 5, characterized in that The external electron donor includes an organosilane compound; Preferably, the external electron donor includes any one of isobutyltriethoxysilane, diisobutyldimethoxysilane, dicyclopentyldimethoxysilane, diphenyldimethoxysilane, methylcyclohexyldimethoxysilane, diisopropyldimethoxysilane, tetraethoxysilane, isopropylisobutyldimethoxysilane, and norbornenetrimethoxysilane, or a combination of at least two thereof.

7. The preparation method according to any one of claims 1 to 6, characterized in that In the system consisting of the main catalyst, the co-catalyst and the external electron donor, the molar ratio of Al, Si and Ti is 50-150:2-10:1; Preferably, in step (1), the mass ratio of the amount of propylene introduced to the main catalyst is 5000 to 50000:1; Preferably, based on 100% by mass of the final product high gloss polypropylene, the amount of ethylene used is 0.1%-5.0%.

8. The preparation method according to any one of claims 1 to 7, characterized in that The polymerization process of step (1) includes any one of a single-reactor process and a process of at least two reactors in series or in parallel; Preferably, the polymerization reaction process in step (1) includes any one of the Hypol process, ST process, Unipol process, and Spheripol process; Preferably, the reactor comprises a polymerization kettle; Preferably, the polymerization reaction time in step (1) is 40-200 min; Preferably, the post-processing includes degassing and screening.

9. The preparation method according to any one of claims 1 to 8, characterized in that The auxiliary agent includes an antioxidant; Preferably, the antioxidant includes a primary antioxidant and / or a secondary antioxidant; Preferably, based on the mass of the final product high gloss polypropylene as 100%, the amount of the antioxidant added is 0.5‰-2‰; Preferably, the auxiliary agent further comprises a halogen absorber and / or an antistatic agent.

10. A high gloss polypropylene, characterized in that: The high-gloss polypropylene is prepared by the preparation method according to any one of claims 1 to 9.

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