A special material for CPP aluminized cast film and its preparation method

Abstract

The present invention relates to a preparation method of a special material for CPP aluminized cast film, comprising the following steps: A mixed gas of ethylene and propylene is polymerized in the presence of hydrogen, nitrogen and Z-N catalyst to obtain a CPP resin. 0.1-0.5 wt% of antioxidant, 0.1-0.2 wt% of anti-blocking agent and 0.1-0.2 wt% of slip agent are added to the CPP resin and mixed evenly, and then melt-extruded and pelletized to obtain a special material for aluminized polypropylene cast film. The base resin of this special material has a sequence structure combining random copolymerization and block copolymerization. This structure can improve the crystallization morphology and enhance the mechanical properties of the product, making the resin exhibit more excellent bending properties and processability. At the same time, by adding a composite additive with high heat resistance and low precipitation, the industry problem of additive precipitation in the special material for cast film is solved, and it is a practical functional film resin.

Description

Technical Field

[0001] The present invention relates to the field of synthetic resins, and particularly to a special material for CPP aluminized cast film and a preparation method thereof. Background Art

[0002] Polypropylene aluminized cast film (CPP) has excellent unique properties such as light-shielding property, decorative property, barrier property, printing and lamination adaptability, etc., and can meet the usage requirements of films for heat resistance, chemical resistance, abrasion resistance, high barrier, etc., and is widely used in the fields of food, medicine, chemical industry, electronics, etc. In 2018, the domestic demand for special materials for aluminized film reached more than 500,000 tons. Only the products of companies such as Zhonghai Shell and Yanshan Petrochemical were used as low-grade aluminized film resins, and all high-grade special materials for aluminized film relied on imports. Typical grades included imported grades such as Basell, Borealis, and Hanwha Total Petrochemical. Compared with general materials, the selling price was 200 - 500 yuan / ton higher, with significant economic benefits and broad market prospects. In recent years, the domestic demand for special materials for the corona layer of CPP aluminized film exceeded 100,000 tons / year, and the demand increased significantly year by year, with good market development prospects. The main performance requirements for this type of resin are: melt index of 8.0 - 10.0 g / 10min, low exudates, and good aluminizing fastness.

[0003] In China, the main equipment for producing CPP is a three-layer coextrusion casting line. The structure of the three-layer coextrusion cast film can generally be divided into a heat-sealing layer, a core layer, and a corona layer. Among them, the heat-sealing layer needs to be heat-sealed, requiring the material to have a low heat-sealing temperature and good opening property. Generally, a ternary copolymerized CPP raw material is used, accounting for 20%; the core layer material determines the mechanical properties of the film. Generally, a homopolymerized CPP raw material is used, accounting for 60%; the corona layer has an appropriate surface tension after surface treatment for printing, lamination, or metallization treatment. Generally, a binary or ternary copolymerized polypropylene is used, accounting for 20%. Correspondingly, the structure of the aluminized grade CPP film is a three-layer composite structure of copolymerized PP / homopolymerized PP / copolymerized PP.

[0004] In order to meet the requirements for the adhesion strength of vapor-deposited aluminum on the surface of aluminized CPP film products and the dimensional stability of the products after vapor deposition, higher requirements are put forward for the molecular structure and properties of the core layer special material: First, the product has high rigidity, providing excellent stiffness to prevent the surface of the film from being easily wrinkled during the high-temperature heat radiation processing; second, there are few low-molecular-weight components to prevent the precipitation of small molecules, which affects the corona and aluminizing properties; third, the additive system is heat-resistant and has good stability, and can withstand high impact during vacuum aluminizing to ensure the surface tension and aluminizing firmness of the aluminized film. The corona treatment layer requires an MFR of 6 - 12 g / 10 min. For the three-layer coextruded CPP film used as a composite substrate, in order to improve its adhesion fastness to ink and the composite strength with other materials, it must be corona-treated. The optimal MFR of the middle layer (core layer, support layer) is 6 - 10 g / 10 min. The core layer plays a supporting role for the film, increasing the stiffness of the film and reducing costs at the same time. It is required that the core layer has excellent rigidity, so mostly homopolymers are used. The weight of the core layer of the three-layer coextruded CPP film accounts for 60% - 70% of the total weight of the film. Secondly, the good optical properties (low haze, high gloss) of the three-layer coextruded CPP film also mainly depend on the core layer. The MFR of the heat-sealing layer (non-treatment layer) is 6 - 12 g / 10 min. In addition to properties such as slipperiness, anti-blocking property, low precipitation amount, and low volatile content, the heat-sealing layer should have good heat-sealing performance, that is, the material should have good hot melt properties and a wide heat-sealing temperature range. The heat-sealing layer uses binary or ternary random copolymers, and the dosage accounts for 15% - 20% of the total film amount.

[0005] The domestic high-end CPP aluminized film production technology is still in its infancy. The special materials for domestic aluminized films mainly have problems such as excessive additive precipitation and low modulus of the special materials, which seriously affect the aluminizing firmness of the aluminized film and the stiffness of the film. The performance of the special materials has not been able to meet the usage requirements of downstream users for high-grade aluminized products.

[0006] CN201610055883.5 discloses a production method of a super-low temperature CPP aluminized film, including the following steps: Step 1: Prepare composite low-temperature particles: fully mix the raw materials with mass percentages of 23-63% of low-temperature non-conductive liquid, 36.5-76.5% of metallocene polyethylene, and 0.5% of dimethyl silicone oil, and the sum of the mass percentages of the raw materials is 100%; then centrifuge in a high-speed centrifuge and carry out a polymerization reaction; then extrude and granulate the material after the polymerization reaction through a twin-screw extruder, and then cool and dry to obtain composite low-temperature particles; Step 2: Fully mix 18-35 parts by weight of the prepared composite low-temperature particles with 54-80 parts by weight of PET, and melt-extrude through a twin-screw extruder, and then cool to obtain a PET base film; Step 3: Corona on the upper surface of the PET base film prepared in Step 2: Carry out corona treatment on the upper surface of the PET base film through a corona machine to increase the dyne coefficient on the surface of the PET base film; Step 4: Carry out vacuum aluminizing on the surface of the corona-treated PET base film through a vacuum aluminizing machine to form an aluminized layer and obtain a super-low temperature CPP aluminized film. Prepare composite low-temperature particles, mix them with the base film, carry out corona on the surface, and then vacuum aluminize. However, there is a large amount of low-temperature non-conductive liquid in the formula of this technology, which increases the industrial production cost.

[0007] Wang Yunhong, "Crystallization Properties and Processing Applications of Special Resins for CPP Films" (Literature Source: Synthetic Resins and Plastics) analyzed and characterized the special materials of Dushanzi Petrochemical Company, and optimized the special resins for CPP films by testing the performance by changing the processing conditions; however, the melting temperature of the products obtained by this technology is relatively low.

[0008] Wang Yunhong, "Development and Production of Special Materials for Polypropylene Cast Films" (Literature Source: Henan Chemical Industry) controlled the relative molecular mass of the products and achieved a unimodal narrow distribution molecular structure by adjusting the hydrogen concentration and the load ratio of two loop reactors; however, the heat-sealing temperature of the products obtained by this technology is high and the haze is slightly large.

[0009] As described above, the existing special materials for aluminized films mainly have problems such as a large amount of additive precipitation and low modulus of the special materials, which seriously affect the aluminizing firmness of the aluminized film and the stiffness of the film, and the performance of the special materials fails to meet the usage requirements of downstream users for high-grade aluminized products. Summary of the Invention

[0010] Based on the above, the purpose of the present invention is to provide a special material for CPP aluminized cast films and its preparation method. The special material for CPP aluminized cast films provided by the present invention can solve the industry problem of additive precipitation in special materials for cast films and is a practical functional film resin.

[0011] To this end, the present invention provides a method for preparing a special material for CPP aluminized cast film, comprising the following steps: A mixed gas of ethylene and propylene is polymerized in the presence of hydrogen, nitrogen and a Ziegler-Natta catalyst to obtain a CPP resin. An antioxidant in an amount of 0.1 to 0.5 wt%, an anti-blocking agent in an amount of 0.1 to 0.2 wt%, and a slip agent in an amount of 0.1 to 0.2 wt% are added to the CPP resin, and the mixture is uniformly mixed, melt-extruded and pelletized to obtain a special material for aluminized polypropylene cast film.

[0012] Specifically, the comonomer is ethylene, which is used to adjust the density of polypropylene; the hydrogen is used to adjust the molecular weight of polypropylene; and the nitrogen is an inert gas used to exclude air.

[0013] Specifically, the present invention adds a composite additive composed of an antioxidant, an anti-blocking agent and a slip agent, which solves the key problems of additive precipitation and poor aluminizing firmness of the special material for cast film. By improving the crystallization morphology through the chain segment structure, the resin exhibits more excellent bending performance and processability.

[0014] In the method for preparing the special material for CPP aluminized cast film according to the present invention, preferably, the polymerization is selected from at least one of slurry polymerization, gas phase polymerization and solution polymerization.

[0015] In the method for preparing the special material for CPP aluminized cast film according to the present invention, preferably, the polymerization temperature is 65 to 85 °C, the reaction pressure is 2 to 4 MPa, and the residence time of the material in the polymerization reactor is 1 to 5 h.

[0016] In the method for preparing the special material for CPP aluminized cast film according to the present invention, preferably, the reactor is a multi-zone gas phase fluidized bed reactor.

[0017] In the method for preparing the special material for CPP aluminized cast film according to the present invention, preferably, in the polymerization process, the molar ratio of ethylene to propylene is 0.01:1 to 0.06:1; the concentration of hydrogen in the reactor is 10 to 1000 ppm; and further preferably, the molar ratio of hydrogen to ethylene is 0.001 to 0.003.

[0018] In the method for preparing the special material for CPP aluminized cast film according to the present invention, preferably, the antioxidant is selected from at least two of antioxidant 1010, antioxidant 168 and antioxidant 264.

[0019] In the method for preparing the special material for CPP aluminized cast film according to the present invention, preferably, the anti-blocking agent is selected from at least two of silicon dioxide, polyethylene oxide, calcium stearate and hydrotalcite.

[0020] The preparation method of the special material for CPP aluminized cast film, preferably, the slip agent is selected from at least two of stearamide, erucamide, hydrotalcite, and polyol fatty acid ester.

[0021] Therefore, the present invention also provides a special material for CPP aluminized cast film prepared by the above preparation method, with a melt index of 6-9 g / 10 min, a molecular weight distribution of 2-5, and an isotacticity of 90-99%.

[0022] The present invention also provides a specific preparation method of the special material for CPP aluminized cast film, and the steps are as follows: (1) Add ethylene, propylene, hydrogen, nitrogen, and Z-N catalyst into a multi-zone gas-phase fluidized bed reactor, and carry out polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.02:1, a hydrogen / ethylene molar ratio of 0.002, a polymerization temperature of 80 °C, a polymerization pressure of 2 MPa, and a residence time of 1.5 h of the material in the reactor to obtain a base resin. (2) Add 0.2 (weight percentage) of antioxidant, 0.1 (weight percentage) of anti-blocking agent, and 0.1 (weight percentage) of slip agent to the base resin and add them to a high-speed mixer, stir and mix, and then carry out extrusion granulation in a twin-screw extruder to obtain a special material for the corona layer of CPP aluminized polypropylene cast film.

[0023] The beneficial effects of the present invention are as follows:

[0024] The base resin of this special material has a sequence structure combining random copolymerization and block copolymerization. This structure can improve the crystal morphology and enhance the mechanical properties of the product, making the resin exhibit more excellent bending performance and processability. At the same time, by adding composite additives with high heat resistance and low precipitation, the industry problem of additive precipitation in the special material for cast film is solved, and it is a practical functional film resin.

[0025] Description of the drawings

[0026] Figure 1 The infrared spectrum diagram of the special material for CPP aluminized cast film prepared in Example 2;

[0027] Figure 2 The DSC diagram of the special material for CPP aluminized cast film prepared in Example 2;

[0028] Figure 3 The nuclear magnetic resonance drawing of the special material for the corona layer of aluminized polypropylene cast film prepared in Example 2. Detailed implementation mode

[0029] The following is a detailed description of the embodiments of the present invention: These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are generally carried out under conventional conditions. All percentages not specified in the following examples and comparative examples are weight percentages.

[0030] The preparation method of the special material for CPP aluminized cast film provided by the present invention includes the following steps: A mixed gas of ethylene and propylene is polymerized in the presence of hydrogen, nitrogen, and a Ziegler-Natta catalyst to obtain a CPP resin. An antioxidant in an amount of 0.1 - 0.5 wt%, an anti-blocking agent in an amount of 0.1 - 0.2 wt%, and a slip agent in an amount of 0.1 - 0.2 wt% are added to the CPP resin, and they are mixed evenly, then melt-extruded and pelletized to obtain the special material for aluminized polypropylene cast film.

[0031] Specifically, the comonomer is ethylene, which is used to adjust the density of polypropylene; the hydrogen is used to adjust the molecular weight of polypropylene; and the nitrogen is an inert gas used to exclude air.

[0032] Specifically, the present invention adds a composite additive composed of a compound of an antioxidant, an anti-blocking agent, and a slip agent, which solves the key problems of additive precipitation and poor aluminizing firmness of the special material for cast film. By improving the crystallization morphology through the chain segment structure, the resin exhibits more excellent bending properties and processability.

[0033] In some embodiments, preferably, the polymerization is selected from at least one of slurry polymerization, gas-phase polymerization, and solution polymerization.

[0034] In some embodiments, preferably, the reaction temperature of the polymerization is 65 - 85 °C, the reaction pressure is 2 - 4 MPa, and the residence time of the material in the polymerization reactor is 1 - 5 h.

[0035] In some embodiments, preferably, the reactor is a multi-zone gas-phase fluidized bed reactor.

[0036] In some embodiments, preferably, during the polymerization process, the molar ratio of ethylene to propylene is 0.01:1 - 0.06:1; the concentration of hydrogen in the reactor is 10 - 1000 ppm; and further preferably, the molar ratio of hydrogen to ethylene is 0.001 - 0.003.

[0037] In some embodiments, preferably, the antioxidant is selected from at least two of antioxidant 1010, antioxidant 168, and antioxidant 264.

[0038] In some embodiments, preferably, the anti-blocking agent is selected from at least two of silica, polyethylene oxide, calcium stearate, and hydrotalcite.

[0039] In some embodiments, preferably, the slip agent is selected from at least two of stearamide, erucamide, hydrotalcite, and polyol fatty acid ester.

[0040] The special material for CPP aluminized cast film prepared by the above preparation method provided by the present invention has a melt index of 6 - 9 g / 10 min, a molecular weight distribution of 2 - 5, and an isotacticity of 90 - 99%.

[0041] Evaluation and analysis parameters: MFR melt index (2.16 kg) g / 10 min: GB / T 3682; molecular weight distribution GB / T36214.2 - 2018; flexural modulus: GB / T 9341; notched izod impact strength: GB / T1043; yield strength: GB / T 1040. Specific embodiments:

[0043] Example 1

[0044] Ethylene, propylene, hydrogen, nitrogen, and Ziegler - Natta catalyst (catalyst model Z - N118) were added to a multi - zone gas - phase fluidized - bed reactor. According to the molar ratio of ethylene / propylene of 0.01:1 and the molar ratio of hydrogen to ethylene of 0.001, polymerization reaction was carried out under the process conditions of a polymerization temperature of 80 °C, a polymerization pressure of 2 MPa, and a residence time of 1 h for the material in the reactor to obtain a base resin (i.e., the special material for CPP aluminized cast film, the same below).

[0045] Antioxidant 1010 and antioxidant 168 in a total amount of 0.1 (weight percentage), anti - blocking agent polyethylene oxide and calcium stearate in a total amount of 0.1 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.1 (weight percentage) were added to the base resin. They were mixed evenly in a mixer and melt - extruded and pelletized in an extruder. The test results of the special material for the corona layer of aluminized polypropylene cast film are shown in Table 1. Among them, the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1, the mass ratio of polyethylene oxide to calcium stearate is 1:1, and the mass ratio of stearamide to hydrotalcite is 1:1.

[0046] Example 2

[0047] Ethylene, propylene, hydrogen, nitrogen, and Ziegler - Natta catalyst (catalyst model Z - N118) were added to a multi - zone gas - phase fluidized - bed reactor. According to the molar ratio of ethylene / propylene of 0.02:1 and the molar ratio of hydrogen to ethylene of 0.002, polymerization reaction was carried out under the process conditions of a polymerization temperature of 80 °C, a polymerization pressure of 2 MPa, and a residence time of 1.5 h for the material in the reactor to obtain a base resin.

[0048] Add 0.2% (by weight) in total of antioxidant 1010 and antioxidant 168, 0.1% (by weight) in total of anti-blocking agent polyethylene oxide and calcium stearate, and 0.1% (by weight) in total of slip agent stearamide and hydrotalcite into the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize in an extruder to prepare the special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1, the mass ratio of polyethylene oxide to calcium stearate is 1:1, and the mass ratio of stearamide to hydrotalcite is 1:1.

[0049] Example 3

[0050] Add ethylene, propylene, hydrogen, nitrogen and Ziegler-Natta catalyst (catalyst model Z-N118) into a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of ethylene / propylene molar ratio of 0.03:1, hydrogen / ethylene molar ratio of 0.003, polymerization temperature of 85 °C, polymerization pressure of 2.5 MPa, and residence time of the material in the reactor of 1.5 h to obtain the base resin.

[0051] Add 0.2% (by weight) in total of antioxidant 1010 and antioxidant 168, 0.2% (by weight) in total of anti-blocking agent polyethylene oxide and calcium stearate, and 0.1% (by weight) in total of slip agent stearamide and hydrotalcite into the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize in an extruder to prepare the special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1, the mass ratio of polyethylene oxide to calcium stearate is 1:1, and the mass ratio of stearamide to hydrotalcite is 1:1.

[0052] Example 4

[0053] Add ethylene, propylene, hydrogen, nitrogen and Ziegler-Natta catalyst (catalyst model Z-N118) into a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of ethylene / propylene molar ratio of 0.04:1, hydrogen / ethylene molar ratio of 0.004, polymerization temperature of 75 °C, polymerization pressure of 3 MPa, and residence time of the material in the reactor of 2 h to obtain the base resin.

[0054] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.2 (weight percentage), anti-blocking agent silica and calcium stearate in a total amount of 0.2 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.2 (weight percentage) to the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize them in an extruder to prepare a special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0055] Example 5

[0056] Add ethylene, propylene, hydrogen, nitrogen, and Z-N catalyst (catalyst model Z-N118) to a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.05:1, a hydrogen-to-ethylene molar ratio of 0.005, a polymerization temperature of 75 °C, a polymerization pressure of 3.5 MPa, and a residence time of 2.5 h for the materials in the reactor to obtain the base resin.

[0057] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.1 (weight percentage), anti-blocking agent silica and calcium stearate in a total amount of 0.2 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.2 (weight percentage) to the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize them in an extruder to prepare a special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0058] Example 6

[0059] Add ethylene, propylene, hydrogen, nitrogen, and Z-N catalyst (catalyst model Z-N118) to a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.06:1, a hydrogen-to-ethylene molar ratio of 0.006, a polymerization temperature of 70 °C, a polymerization pressure of 4 MPa, and a residence time of 3 h for the materials in the reactor to obtain the base resin.

[0060] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.15 (weight percentage), anti-blocking agent silica and calcium stearate in a total amount of 0.15 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.15 (weight percentage) to the base resin. Mix them evenly in a mixer and then melt extrude and pelletize them in an extruder to prepare a special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0061] Example 7

[0062] Add ethylene, propylene, hydrogen, nitrogen, and Ziegler-Natta catalyst (catalyst model Z-N118) to a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.05:1, a molar ratio of hydrogen to ethylene of 0.007, a polymerization temperature of 65 °C, a polymerization pressure of 2 MPa, and a residence time of 3.5 h for the material in the reactor to obtain the base resin.

[0063] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.2 (weight percentage), anti-blocking agent silica and calcium stearate in a total amount of 0.15 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.15 (weight percentage) to the base resin. Mix them evenly in a mixer and then melt extrude and pelletize them in an extruder to prepare a special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0064] Example 8

[0065] Add ethylene, propylene, hydrogen, nitrogen, and Ziegler-Natta catalyst (catalyst model Z-N118) to a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.04:1, a molar ratio of hydrogen to ethylene of 0.01, a polymerization temperature of 65 °C, a polymerization pressure of 2 MPa, and a residence time of 3.5 h for the material in the reactor to obtain the base resin.

[0066] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.2 (weight percentage), anti-blocking agent silica and calcium stearate in a total amount of 0.15 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.15 (weight percentage) to the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize them in an extruder to prepare a special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0067] Example 9

[0068] Add ethylene, propylene, hydrogen, nitrogen, and Z-N catalyst (catalyst model Z-N118) to a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.03:1, a molar ratio of hydrogen to ethylene of 0.01, a polymerization temperature of 85 °C, a polymerization pressure of 2 MPa, and a residence time of the material in the reactor of 4 h to obtain the base resin.

[0069] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.2 (weight percentage), anti-blocking agent silica and calcium stearate in a total amount of 0.15 (weight percentage), and slip agent stearamide and hydrotalcite in a total amount of 0.15 (weight percentage) to the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize them in an extruder to prepare a special material for the corona layer of aluminized polypropylene cast film. The test results are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0070] Comparative Example 1

[0071] Add ethylene, propylene, hydrogen, nitrogen, and Z-N catalyst (catalyst model Z-N118) to a multi-zone gas-phase fluidized bed reactor. Carry out the polymerization reaction under the process conditions of an ethylene / propylene molar ratio of 0.02:1, a molar ratio of hydrogen to ethylene of 0.01, a polymerization temperature of 80 °C, a polymerization pressure of 2 MPa, and a residence time of the material in the reactor of 5 h to obtain the base resin.

[0072] Add antioxidant 1010, antioxidant 168, and antioxidant 264 in a total amount of 0.2% (by weight), anti-blocking agent silica and calcium stearate in a total amount of 0.2% (by weight), and slip agent stearamide and hydrotalcite in a total amount of 0.2% (by weight) to the base resin. Mix them evenly in a mixer and then melt-extrude and pelletize them in an extruder. The test results of the special material for the corona layer of aluminized polypropylene cast film are shown in Table 1. Among them, the mass ratio of antioxidant 1010, antioxidant 168, and antioxidant 264 is 1:1:1, the mass ratio of silica and calcium stearate is 1:1, and the mass ratio of stearamide and hydrotalcite is 1:1.

[0073] Table 1 Physical Property Tests of Polymerization Products

[0074]

[0075] As can be seen from Examples 1-9 and Table 1, for the special material for CPP aluminized cast film involved in the present invention, the base resin has a sequence structure combining random copolymerization and block copolymerization. This structure can improve the crystal morphology and enhance the mechanical properties of the product, making the resin exhibit more excellent bending properties and processability. At the same time, by adding composite additives with high heat resistance and low precipitation, the heat resistance of the CPP special material is improved, solving the industry problem of additive precipitation in the special material for cast film, and enabling it to meet various industry standards and the usage requirements of downstream users for high-grade aluminized products. The process is simple, easy to use, convenient for realizing production automation, improving labor productivity, avoiding environmental pollution, and being conducive to clean and civilized production that is beneficial to the health of workers. It is a practical functional film resin.

[0076] Of course, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the present invention.

Claims

1. A preparation method of a special material for CPP aluminized cast film, characterized in that, Comprising the following steps: A mixed gas of ethylene and propylene is polymerized in the presence of hydrogen, nitrogen, and a Ziegler-Natta catalyst to obtain a CPP resin. 0.1 to 0.5 wt% of an antioxidant, 0.1 to 0.2 wt% of an anti-blocking agent, and 0.1 to 0.2 wt% of a slip agent are added to the CPP resin and mixed evenly, then melt-extruded and pelletized to obtain a special material for aluminized polypropylene cast film; during the polymerization process, the molar ratio of ethylene to propylene is 0.01:1 to 0.06:1; the concentration of hydrogen in the reactor is 10 to 1000 ppm; the molar ratio of hydrogen to ethylene is 0.001 to 0.

003.

2. The preparation method of the special material for CPP aluminized cast film according to claim 1, characterized in that, The polymerization is selected from at least one of slurry polymerization, gas-phase polymerization, and solution polymerization.

3. The preparation method of the special material for CPP aluminized cast film according to claim 1, characterized in that, The reaction temperature of the polymerization is 65 to 85 °C, the reaction pressure is 2 to 4 MPa, and the residence time of the material in the polymerization reactor is 1 to 5 h.

4. The preparation method of the special material for CPP aluminized cast film according to claim 3, characterized in that, The reactor is a multi-zone gas-phase fluidized bed reactor.

5. The preparation method of the special material for CPP aluminized cast film according to claim 1, characterized in that The antioxidant is selected from at least two of antioxidant 1010, antioxidant 168, and antioxidant 264.

6. The preparation method of the special material for CPP aluminized cast film according to claim 1, wherein, The anti-blocking agent is selected from at least two of silica, polyethylene oxide, and calcium stearate.

7. The preparation method of the special material for CPP aluminized cast film according to claim 1, characterized in that, The slip agent is selected from at least two of stearamide, erucamide, hydrotalcite, and polyol fatty acid ester.

8. The preparation method of the special material for CPP aluminized cast film according to claim 1, characterized in that The Ziegler-Natta catalyst comprises Mg, Ti, halogen, and an internal electron donor compound.

9. A special material for CPP aluminized cast film prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The melt index is 6 to 9 g / 10min, the molecular weight distribution is 2 to 5, and the isotacticity is 90 to 99%.

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