A broad distribution easy processable polyethylene and its use

Abstract

The application discloses a kind of wide distribution easy processing polyethylene and its application.The weight average molecular weight of the wide distribution easy processing polyethylene is 10×10 4 -45×10 4 G / mol, molecular weight distribution is 35-50, the component content of molecular weight ≥100×10 4 G / mol is 1-10wt%, the component content of molecular weight ≤1000g / mol is 0.5-2.5wt%, density is 0.940-0.960g / cm 3 , melt index is 8-15g / 10min, branched chain content ≤0.2C / 1000C, breaking tensile strength ≥50MPa.The matt material consisting of wide distribution easy processing polyethylene and polypropylene is applied to multilayer co-extrusion casting film, with the characteristics of high haze, small haze deviation, high water vapor barrier performance.

Description

Technical Field

[0001] This invention relates to a polyolefin material, and more specifically, to a wide-distribution, easily processable polyethylene and its applications. Background Technology

[0002] BOPP matte film is a special type of biaxially oriented polypropylene (BOPP) film with high haze and low gloss optical properties. This film is manufactured using a special process, resulting in a diffuse, matte finish similar to paper, with soft reflected light and a delicate appearance. Due to its unique optical and surface properties, BOPP matte film is widely used in various packaging materials, such as packaging for food, tobacco, cosmetics, and pharmaceuticals, as well as for book and magazine covers and promotional posters.

[0003] The production process of BOPP matte film includes steps such as batching, extrusion, casting, biaxial stretching, traction, winding, aging, and slitting. During production, a certain amount of matting agent is added to the surface of the film to improve its haze. This matting agent is typically made by blending polypropylene and polyethylene in a specific ratio, with the addition of small amounts of plasticizers and antioxidants, and then granulating the mixture. Compared to polypropylene, polyethylene crystallizes much faster, forming larger crystal particles during biaxial stretching. This roughens the film surface, causing light scattering and thus creating the matte effect.

[0004] However, the current BOPP production line has differences in the stretch ratio on both sides and in the middle, resulting in significant differences in light transmittance and haze between the top and bottom sides and the middle portion of the matte film. The top and bottom sides of the matte film have significantly higher light transmittance and lower haze. To eliminate this optical defect, the matte layer on the surface of the matte film is often thickened, leading to higher overall costs and limited profit margins. Furthermore, the difference in stretch ratio between the two sides and the middle portion of the film is also partly attributed to the low flowability of the blended matte material of polyethylene and polypropylene. Invention patent CN111117077A discloses a matte material for BOPP, its preparation method, and a BOPP matte film. The BOPP matte material comprises the following raw materials by weight percentage: 40%-60% copolymer polypropylene, 35%-55% high-density polyethylene, 5%-15% masterbatch A, and 0.5%-5% antioxidant masterbatch; wherein masterbatch A includes a masterbatch matrix, hydrogenated petroleum resin, or rosin resin, and the masterbatch matrix is ​​polypropylene. By adding masterbatch A containing hydrogenated petroleum resin or rosin resin to the formulation system, the melt flow rate of masterbatch A in the molten state is significantly higher than that of copolymer polypropylene and high-density polyethylene, which greatly improves the overall flowability and dispersibility of the matting material. Therefore, it improves the overall matting uniformity of the BOPP matting film. Without thickening the matting layer, it improves the problem of uneven matting dispersion on both sides of the existing matting film, improves the overall matting effect of the BOPP matting film and increases production efficiency.

[0005] Therefore, developing a polyethylene resin suitable for blending with polypropylene, which takes into account high fluidity, high haze and low haze deviation, and its blending matting agent with polypropylene, is crucial for reducing the matting layer of matting film, increasing processing speed, and enhancing market competitiveness. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a wide-distribution easily processable polyethylene and its application. The wide-distribution easily processable polyethylene has the characteristics of excellent processing performance, good flowability, wide molecular weight distribution and fast crystallization rate.

[0007] According to one objective of the present invention, a broad-distribution, easily processable polyethylene is provided, wherein the weight-average molecular weight of the broad-distribution, easily processable polyethylene is 10 × 10⁻⁶. 4 -45×10 4 g / mol, molecular weight distribution in the range of 35-50, molecular weight ≥100×10 4 The component content is 1-10 wt% (g / mol), the component content is 0.5-2.5 wt% (molecular weight ≤ 1000 g / mol), and the density is 0.940-0.960 g / cm³. 3 Melt index is 8-15 g / 10 min, branched content is <0.2 C / 1000 C, and tensile strength at break is ≥50 MPa.

[0008] The present invention also provides a method for preparing the aforementioned wide-distribution, easily processable polyethylene, comprising:

[0009] In the first reactor, polymer A is dissolved in solvent B, and co-catalyst C and catalyst D are added sequentially. α-olefin E and ethylene are then introduced to initiate the polymerization reaction. The polymerization temperature is T1, the polymerization time is t, and the polymerization pressure is P1. After the polymerization reaction is completed, the slurry in the first reactor is introduced into the product collection tank at a flow rate X1 (flow rate is based on the weight of the solid product). The concentration of polymer A in the first reactor is 0.1-10.0 wt%, and the weight-average molecular weight of polymer A is ≤1000 g / mol.

[0010] Meanwhile, in the second reactor, solvent B is used as the polymerization medium, the polymerization temperature is T2, the polymerization pressure is P2, and the co-catalyst F, catalyst G, α-olefin H and ethylene are continuously introduced for continuous production. The slurry in the second reactor is introduced into the product collection tank at a flow rate of X2 (the flow rate is based on the weight of the solid product).

[0011] The first and second reactors are connected in parallel for production;

[0012] The mixed slurry in the product collection tank is introduced into a solid-liquid separator at a temperature of T3. The solid phase product separated by the solid-liquid separator is dried, devolatilized, and extruded and granulated to obtain the wide-distribution, easily processed polyethylene product. The separated liquid phase product can be further refined to obtain solvent B for use in the first and second reaction vessels.

[0013] According to a preferred embodiment of the present invention, polymer A is selected from one or more of polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, polybutene, paraffin wax, and Fischer-Tropsch wax.

[0014] According to a preferred embodiment of the present invention, the concentration of polymer A in the first reaction vessel is 0.1-10.0 wt%, solvent B is selected from one or more of n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, methylcyclohexane, 2-methylpentane, 3-methylpentane, n-heptane, 2-methylhexane, 3-methylhexane, n-octane, 2-methylheptane, 3-methylheptane, n-nonane, and n-decane; co-catalyst C and co-catalyst F are selected from methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, butylaluminoxane, trimethylaluminum, triethylaluminum, and triisocyanate. The catalysts are selected from one or more of butylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, diethylaluminum chloride, triphenylborane, tris(4-fluorophenyl)borane, tris(pentafluorophenyl)borane, tris(3,5-difluorophenyl)borane, and tris(2,4,6-trifluorophenyl)borane, and the co-catalysts C and F may be the same or different; catalysts D and G are selected from one or more of metallocene catalysts, post-transition metal catalysts, Ziegler-Natta catalysts, non-metallocene catalysts, and FI catalysts, and catalysts D and G may be the same or different.

[0015] α-olefin E and α-olefin H are selected from one or more of propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, or 1-decene, and α-olefin E and α-olefin H may be the same or different. The amount of α-olefin E and α-olefin H added usually needs to be selected in conjunction with the catalytic activity of the catalyst to ensure that the branched content in the final product is <0.2C / 1000C.

[0016] The polymerization temperature T1 is 50-90℃, the polymerization time t is 0.5-10h, and the polymerization pressure P1 is 0.5-2.0MPa.

[0017] According to a preferred embodiment of the present invention, the solid product in the slurry in the first reactor contains polymer A at a content of 0.5-8.0 wt%, polymer A has a weight-average molecular weight <1000 g / mol, and the weight-average molecular weight of the solid product in the slurry in the first reactor is 80-140 × 10⁻⁶. 4 The molecular weight distribution is 50-500 g / mol, the branching content is <0.2C / 1000C, and the initial elastic modulus of the solid product excluding polymer A is 0.2-0.5MPa.

[0018] According to a preferred embodiment of the present invention, polymer A is widely distributed on the surface and inside the particles of the solid product in the slurry in the first reactor, and the surface of the solid product is scaly, with polymer A distributed between the scaly crystals, and the thickness of the scaly crystals is 10-300 nm.

[0019] According to a preferred embodiment of the present invention, the polymerization temperature T2 is 60-100℃, the polymerization pressure P2 is 0.5-2.0MPa, and the solid-liquid separator temperature T3 is 40-55℃.

[0020] According to a preferred embodiment of the present invention, the ratio of the slurry flow rate X1 in the first reactor to the slurry flow rate X2 in the second reactor is 1:(1.5-9.9), and the polymer A content in the widely distributed, easily processed polyethylene product is 0.3-2.5 wt%. The weight-average molecular weight of the solid product in the slurry in the second reactor is 10 × 10⁻⁶. 4 -20×10 4 g / mol, with a molecular weight distribution in the range of 10-30.

[0021] According to a preferred embodiment of the present invention, the high-temperature gel permeation chromatography spectrum of the widely distributed, easily processed polyethylene product exhibits a distinct bimodal distribution.

[0022] According to a second objective of the present invention, the present invention provides the application of the wide-distribution, easily processable polyethylene in the preparation of matte films.

[0023] According to a preferred embodiment of the present invention, widely distributed easily processed polyethylene is mixed with copolymer polypropylene, a slip agent, and an antioxidant in a weight ratio of 1:(0.8-1.2):(0.02-0.03):(0.001-0.003), and then melt-co-extruded and biaxially stretched to form a surface matte layer for use as a matte film. The matte film has a three-, four-, five-, six-, or seven-layer structure. The surface matte layer can be a single layer or can exist simultaneously as both the outer and inner surface layers of the matte film (double layer). A single-layer matte film has a haze ≥80% and a haze deviation ≤0.3% on the upper and lower sides and the middle portion. A double-layer matte film has a haze ≥90% and a haze deviation ≤0.5% on the upper and lower sides and the middle portion. Furthermore, this matte film also has the advantage of high water vapor barrier properties, with a water vapor transmission rate ≤3.5 g / (m²). 2 •24h).

[0024] Among them, slip agents are used to improve the slip properties of plastic surfaces, reduce the coefficient of friction of plastic surfaces, and improve the processing performance of plastics and the performance of products. They can be commonly used slip agents in this field, such as oleamide, erucamide, calcium stearate, silicone, and low molecular weight polypropylene. Antioxidants are used to slow down the auto-oxidation rate of polymer materials. They can be commonly used antioxidants in this field, such as 1010 antioxidant and XX.

[0025] The present invention has the following outstanding gain effects:

[0026] (1) The wide-distribution, easily processable polyethylene of this invention has a wide molecular weight distribution. The low molecular weight polymer A component can melt rapidly and has extremely strong molecular chain mobility, which can promote the movement of high molecular weight polyethylene molecular chains around the polymer A molecular chains. Therefore, the processing temperature required during melt processing is lower, resulting in better processability and processing economy. When this wide-distribution, easily processable polyethylene is blended with copolymer polypropylene as a matting material, it has better fluidity during melt co-extrusion and biaxial stretching, which significantly reduces the haze error on the upper and lower sides and the middle part of single-layer and double-layer matting films.

[0027] (2) The widely distributed, easily processable polyethylene of this invention is produced by a dual-reactor parallel process. The molecular weight distribution of the solid product in the first reactor is 50-500, and the initial elastic modulus of the solid product excluding polymer A is 0.2-0.5 MPa. This indicates that the solid product in the first reactor has the characteristics of low entanglement and wide distribution. Low-entanglement polyethylene has stronger molecular chain mobility and a faster crystallization rate during melt processing and biaxial stretching, resulting in higher tensile strength of polyethylene. In addition, the weight-average molecular weight of the solid product in the slurry in the first reactor is 80-140 × 10⁻⁶. 4 This low-entanglement polyethylene, with a molecular weight of g / mol, also has the characteristics of high molecular weight. According to the knowledge in the field of polymer physics, the higher the molecular weight, the faster the molecular chain crystallizes. This further widens the difference in crystallization rate between polyethylene and polypropylene in the matting material, thus further improving the haze of the matting layer and matting film.

[0028] (3) The branched content of the wide-distribution, easily processed polyethylene of the present invention is <0.2C / 1000C, and the branched content of the solid product in the slurry in the first reaction vessel is <0.2C / 1000C. The lower the branched content, the faster the crystallization rate of the polyethylene molecular chain. This also further widens the difference in crystallization rate between polyethylene and polypropylene in the matte material, and the haze of the matte layer and matte film can be further improved. Attached Figure Description

[0029] Figure 1 It is the elastic modulus G'-time t curve of the solid product in the first reaction vessel after removing polymer A at 160℃.

[0030] Figure 2 This is the GPC curve of the solid products in the first reactor. Detailed Implementation

[0031] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0032] The following methods are used to test the structure or properties of the polyolefins produced in the embodiments described:

[0033] High-temperature gel permeation chromatography (GPC) is used to test the weight-average molecular weight and molecular weight distribution of polyethylene.

[0034] Gradient density meters are used to test the density of polyethylene.

[0035] A melt flow indexer is used to test the melt flow index of polyethylene.

[0036] Analytical temperature wash fractionation (TREF) is used to test the short-chain branch content of polyethylene.

[0037] The universal testing machine is used to test the tensile strength of polyethylene.

[0038] The content of polymer A in the polyethylene product was separated by xylene heating and rinsing, and the mass content was calculated by weighing.

[0039] A rotational rheometer is used to test the initial elastic modulus of polyethylene.

[0040] A haze meter is used to test the haze of a thin film.

[0041] Thickness gauges are used to test the thickness of thin films.

[0042] A water vapor transmission rate tester is used to test the water vapor transmission rate of a thin film.

[0043] Example 1

[0044] 120 kg of Fischer-Tropsch wax (weight-average molecular weight 650 g / mol) was dissolved at a concentration of 2.4 wt% in the first reaction vessel (the medium was hexane, volume 10 m³). 3 ), 1.3 L of triethylaluminum, 12 g of Ziegler-Natta catalyst, and 40 L of 1-hexene were added sequentially, and ethylene was introduced to start polymerization. The polymerization temperature was 57 °C, the polymerization time (residence time) was 3.3 h, and the polymerization pressure was 1.0 MPa; the second reactor (volume 40 m³) 3The polymerization process used hexane as the polymerization medium, with a polymerization temperature of 88℃ and a polymerization pressure of 1.3MPa. Triethylaluminum, Ziegler-Natta catalyst, 1-hexene, and ethylene were continuously introduced for continuous production. The first and second reactors were operated in parallel. The slurry from the first reactor was introduced into the product collection tank at a rate of 1 t / h, and the slurry from the second reactor was introduced into the product collection tank at a rate of 6.5 t / h. The mixed slurry in the product collection tank was introduced into a solid-liquid separator at a temperature of 45℃. The solid product separated by the solid-liquid separator was dried, devolatilized, and extruded into granules to obtain a broad-distribution, easily processable polyethylene product a. The analytical and characterization results of product a are shown in Table 1.

[0045] Example 2

[0046] 125 kg of microcrystalline wax (weight average molecular weight 800 g / mol) was dissolved at a concentration of 2.5 wt% in the first reaction vessel (medium: cyclohexane, volume 10 m³). 3 ), 1.2 L of triisobutylaluminum, 18 g of Ziegler-Natta catalyst, and 60 L of 1-hexene were added sequentially, and ethylene was introduced to start polymerization. The polymerization temperature was 63℃, the polymerization time (residence time) was 3 h, and the polymerization pressure was 0.9 MPa; the second reactor (volume 40 m³) 3 Cyclohexane was used as the polymerization medium, the polymerization temperature was 84℃, and the polymerization pressure was 1.8MPa. Triisobutylaluminum, Ziegler-Natta catalyst, 1-hexene, and ethylene were continuously introduced for continuous production. The first and second reactors were operated in parallel. The slurry from the first reactor was introduced into the product collection tank at a rate of 1.1 t / h, and the slurry from the second reactor was introduced into the product collection tank at a rate of 5.9 t / h. The mixed slurry in the product collection tank was introduced into a solid-liquid separator at a temperature of 51℃. The solid product separated by the solid-liquid separator was dried, devolatilized, and extruded and granulated to obtain a wide-distribution, easily processable polyethylene product b. The analytical and characterization results of product b are shown in Table 1.

[0047] Example 3

[0048] 100 kg of paraffin (weight average molecular weight 500 g / mol) was dissolved at a concentration of 2.0 wt% in the first reaction vessel (medium: cyclohexane, volume 10 m³). 3 ), 1.2 L of modified methylaluminoxane, 15 g of supported metallocene catalyst, 20 L1-hexene, and 40 L1-octene were added sequentially, and ethylene was introduced to start polymerization. The polymerization temperature was 73℃, the polymerization time (residence time) was 2.1 h, and the polymerization pressure was 1.5 MPa; the second reactor (volume 40 m³) 3Cyclohexane was used as the polymerization medium, the polymerization temperature was 82℃, and the polymerization pressure was 1.3MPa. Modified methylaluminoxane, a supported metallocene catalyst, 1-hexene, and ethylene were continuously introduced for continuous production. The first and second reactors were connected in parallel. The slurry from the first reactor was introduced into the product collection tank at a rate of 0.9 t / h, and the slurry from the second reactor was introduced into the product collection tank at a rate of 3.9 t / h. The mixed slurry in the product collection tank was introduced into a solid-liquid separator at a temperature of 54℃. The solid product separated by the solid-liquid separator was dried, devolatilized, and extruded and granulated to obtain a wide-distribution, easily processable polyethylene product c. The analytical characterization results of product c are shown in Table 1.

[0049] Example 4

[0050] 200 kg of polyethylene wax (weight average molecular weight 800 g / mol) was dissolved at a concentration of 4.0 wt% in the first reaction vessel (the medium was n-hexane, volume 10 m³). 3 ), 0.8 L of triethylaluminum, 14 g of Ziegler-Natta catalyst, and 80 L of 1-hexene were added sequentially, and ethylene was introduced to start polymerization. The polymerization temperature was 74 °C, the polymerization time (residence time) was 4.2 h, and the polymerization pressure was 0.9 MPa; the second reactor (volume 40 m³) 3 The polymerization medium was n-hexane, the polymerization temperature was 84℃, and the polymerization pressure was 1.4MPa. Triethylaluminum, a supported metallocene catalyst, 1-hexene, and ethylene were continuously introduced for continuous production. The first and second reactors were operated in parallel. The slurry from the first reactor was introduced into the product collection tank at a rate of 1.4 t / h, and the slurry from the second reactor was introduced into the product collection tank at a rate of 5.6 t / h. The mixed slurry in the product collection tank was introduced into a solid-liquid separator at a temperature of 42℃. The solid product separated by the solid-liquid separator was dried, devolatilized, and extruded and granulated to obtain a wide-distribution, easily processable polyethylene product d. The analytical and characterization results of product d are shown in Table 1.

[0051] Comparative Example 1

[0052] First reactor (volume 10m³) 3 In a reactor using n-hexane as the polymerization medium, 1.0 L of triethylaluminum, 13 g of Ziegler-Natta catalyst, and 40 L of 1-hexene were added sequentially. Ethylene was then introduced to initiate polymerization. The polymerization temperature was 67 °C, the polymerization time (residence time) was 4.3 h, and the polymerization pressure was 0.7 MPa. The second reactor (volume 40 m³)... 3The polymerization process used n-hexane as the polymerization medium, with a polymerization temperature of 87℃ and a polymerization pressure of 1.2MPa. Triethylaluminum, Ziegler-Natta catalyst, 1-hexene, and ethylene were continuously introduced for continuous production. The first and second reactors were operated in parallel. The slurry from the first reactor was introduced into the product collection tank at a rate of 1.3 t / h, and the slurry from the second reactor was introduced into the product collection tank at a rate of 5.6 t / h. The mixed slurry in the product collection tank was introduced into a solid-liquid separator at a temperature of 43℃. The solid product separated by the solid-liquid separator was dried, devolatilized, and extruded into granules to obtain polyethylene product e. The analytical characterization results of product e are shown in Table 1.

[0053] Table 1 Characterization results of polyethylene (e)

[0054]

[0055]

[0056] As shown in Table 1 above, the polyethylene products ad from Examples 1-4, compared to polyethylene product e in Comparative Example 1, exhibit a higher melt index, a wider molecular weight distribution, and a higher tensile strength at break. This indicates that polyethylene product ad possesses better processability and mechanical properties. Furthermore, polyethylene product ad contains a higher content of polymer A, and the initial elastic modulus of the solid phase product in the first reaction vessel after removing polymer A is lower (0.27-0.38 MPa, see Appendix). Figure 1 The molecular weight distribution of the solid products in the first reactor is very broad (see appendix). Figure 2 Furthermore, the surface of the solid product in the first reactor, excluding polymer A, exhibits a scaly texture. In contrast, polyethylene product e, which does not contain polymer A, has an initial elastic modulus as high as 0.83 MPa, and its surface lacks a distinct scaly, lamellar structure. These results indicate that the molecular chains of polyethylene product e exhibit high entanglement. Due to the influence of entanglement points, the molecular chains are difficult to open rapidly, resulting in weak chain mobility and difficulty in rapid crystallization during melt processing and biaxial stretching. This leads to a lower melt index, greater processing difficulty, and reduced economic efficiency in the processing of polyethylene product e.

[0057] Example 5

[0058] 100 parts of polyethylene product a, 100 parts of polypropylene (melt 10.5 g / 10 min), 2 parts of slip agent and 0.2 parts of commercial 1010 antioxidant from Example 1 were mixed in a high-speed mixer for 3 min, then melt-extruded and granulated in a twin-screw extruder and dried at a granulation temperature of 235°C to obtain matte material A.

[0059] A three-layer co-extrusion casting machine was used to cast a film with 100 parts of matte material A, 500 parts of intermediate layer material, and 200 parts of inner surface layer material. The extruder temperature was 240℃, the die temperature was 235℃, the longitudinal stretching temperature was 125℃, the setting temperature was 130℃, the transverse stretching temperature was 155℃, and the setting temperature was 166℃. The longitudinal stretching was 4.8 times and the transverse stretching was 8 times, resulting in matte film A. The characterization results of matte film A are shown in Table 2.

[0060] Example 6

[0061] 100 parts of polyethylene product b from Example 2, 90 parts of polypropylene (melt 10.5 g / 10 min), 2 parts of slip agent and 0.1 parts of commercially available 1010 antioxidant were mixed in a high-speed mixer for 3 min, then melt-extruded and granulated in a twin-screw extruder and dried at a granulation temperature of 240°C to obtain matte material B.

[0062] A mixture of 100 parts matte material B, 550 parts intermediate layer material, and 200 parts inner surface layer material was cast into a film using a three-layer co-extrusion casting machine. The extruder temperature was 240℃, the die temperature was 236℃, the longitudinal stretching temperature was 126℃, the setting temperature was 131℃, the transverse stretching temperature was 155℃, and the setting temperature was 167℃. The longitudinal stretching was 4.8 times, and the transverse stretching was 8 times, resulting in matte film B. The characterization results of matte film B are shown in Table 2.

[0063] Example 7

[0064] 100 parts of polyethylene product C from Example 3, 110 parts of polypropylene (melt 11.5 g / 10 min), 3 parts of slip agent and 0.3 parts of commercially available 1010 antioxidant were mixed in a high-speed mixer for 3 min, then melt-extruded and granulated in a twin-screw extruder and dried at a granulation temperature of 240°C to obtain matte material C.

[0065] A three-layer co-extrusion casting machine was used to cast a film with 110 parts of matte material C, 600 parts of intermediate layer material, and 220 parts of inner surface layer material. The extruder temperature was 240℃, the die temperature was 235℃, the longitudinal stretching temperature was 125℃, the setting temperature was 130℃, the transverse stretching temperature was 155℃, and the setting temperature was 166℃. The longitudinal stretching was 4.8 times and the transverse stretching was 8 times, resulting in matte film C. The characterization results of matte film C are shown in Table 2.

[0066] Example 8

[0067] 100 parts of polyethylene product d from Example 4, 1150 parts of polypropylene (melt 10.3 g / 10 min), 3 parts of slip agent and 0.3 parts of commercially available 1010 antioxidant were mixed in a high-speed mixer for 3 min, then melt-extruded and granulated in a twin-screw extruder and dried at a granulation temperature of 238°C to obtain matte material D.

[0068] A mixture of 100 parts matte material D, 650 parts intermediate layer material, and 200 parts inner surface layer material was cast into a film using a three-layer co-extrusion casting machine. The extruder temperature was 240℃, the die temperature was 235℃, the longitudinal stretching temperature was 125℃, the setting temperature was 130℃, the transverse stretching temperature was 155℃, and the setting temperature was 166℃. The longitudinal stretching was 4.8 times, and the transverse stretching was 8 times, resulting in matte film D. The characterization results of matte film D are shown in Table 2.

[0069] Comparative Example 2

[0070] 100 parts of polyethylene product e, 100 parts of polypropylene (melt 10.5 g / 10 min), 2 parts of slip agent and 0.3 parts of commercial 1010 antioxidant from Comparative Example 1 were mixed in a high-speed mixer for 3 min, then melt-extruded and granulated in a twin-screw extruder and dried at a granulation temperature of 238℃ to obtain matte material E.

[0071] A mixture of 100 parts matte material E, 520 parts intermediate layer material, and 200 parts inner surface layer material was cast into a film using a three-layer co-extrusion casting machine. The extruder temperature was 240℃, the die temperature was 235℃, the longitudinal stretching temperature was 125℃, the setting temperature was 130℃, the transverse stretching temperature was 155℃, and the setting temperature was 166℃. The longitudinal stretching was 4.8 times, and the transverse stretching was 8 times, resulting in matte film E. The characterization results of matte film E are shown in Table 2.

[0072] Table 2. AE characterization results of matte film

[0073]

[0074] As shown in Table 2 above, the matte film AD in Examples 5-8 exhibits higher haze compared to the matte film E in Comparative Example 2, and the haze deviation (highest value minus lowest value) is no higher than 0.2%. This is mainly due to the stronger molecular chain mobility of polyethylene in matte material AD and the enhanced crystallization ability of polyethylene molecular chains, which widens the difference in crystallization rate between polyethylene and polypropylene molecular chains, increases the unevenness of the matte film surface, and thus enhances the diffuse reflection behavior of light, resulting in increased haze. Furthermore, the better flowability of polyethylene AD in matte material AD significantly reduces the haze error on the upper and lower sides and in the middle of the matte film. In addition, the matte film AD exhibits excellent water vapor barrier properties, with its water vapor transmittance consistently below 3.3 g / (m²). 2 (24h), significantly lower than the 6.82 g / (m²) of the matte film E. 2 •24h).

[0075] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A broad distribution easily processable polyethylene characterized in that, The broad distribution easy processable polyethylene has a weight average molecular weight of 10 x 10 4 - 45 x 10 4 - 4 g / mol, a molecular weight distribution of 35-50, a component content of 1-10 wt% of a molecular weight of > 100 x 10 4 - 4 g / mol, a component content of 0.5-2.5 wt% of a molecular weight of < 1000 g / mol, a density of 0.940-0.960 g / cm 3 - 3, a melt index of 8-15 g / 10 min, a branching content of < 0.2 C / 1000 C, a tensile strength at break of > 50 MPa; The wide distribution easy processing polyethylene is prepared by the following steps: In the first reactor, polymer A is dissolved in solvent B, and then co-catalyst C and catalyst D are added, and α-olefin E and ethylene are introduced to start the polymerization reaction, the polymerization temperature is T1, the polymerization time is t, and the polymerization pressure is P1; after the polymerization reaction is completed, the slurry in the first reactor is introduced into the product collection tank at a flow rate of X1; the concentration of polymer A in the first reactor is 0.1-10.0 wt%, and the weight average molecular weight of polymer A is ≤1000 g / mol; At the same time, in the second reactor, solvent B is used as the polymerization medium, the polymerization temperature is T2, the polymerization pressure is P2, and co-catalyst F, catalyst G, α-olefin H and ethylene are continuously introduced for continuous production, and the slurry in the second reactor is introduced into the product collection tank at a flow rate of X2; The first reactor and the second reactor are connected in parallel for production; The mixed slurry in the product collection tank is introduced into a solid-liquid separator, the temperature of the solid-liquid separator is T3, and the solid phase product separated by the solid-liquid separator is dried, devolatilized and extruded to obtain the wide distribution easy processing polyethylene product; Polymer A is selected from one or more of polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, polybutene, paraffin wax and Fischer-Tropsch wax; Solvent B is selected from one or more of n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, methylcyclohexane, 2-methylpentane, 3-methylpentane, n-heptane, 2-methylhexane, 3-methylhexane, n-octane, 2-methylheptane, 3-methylheptane, n-nonane and n-decane; Co-catalyst C and co-catalyst F are selected from one or more of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, butylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, monochlorodiethylaluminum, dichloroethylaluminum, triphenylborane, tris(4-fluorophenyl)borane, tris(pentafluorophenyl)borane, tris(3,5-difluorophenyl)borane and tris(2,4,6-trifluorophenyl)borane, and co-catalyst C and co-catalyst F can be the same or different; Catalyst D and catalyst G are selected from one or more of metallocene catalyst, late transition metal catalyst, Ziegler-Natta catalyst, non-metallocene catalyst and FI catalyst, and catalyst D and catalyst G can be the same or different; α-olefin E and α-olefin H are selected from one or more of propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene, and α-olefin E and α-olefin H can be the same or different; The polymerization temperature T1 is 50-90 ℃, the polymerization time t is 0.5-10 h, and the polymerization pressure P1 is 0.5-2.0 MPa; The polymerization temperature T2 is 60-100 ℃, the polymerization pressure P2 is 0.5-2.0 MPa, and the temperature T3 of the solid-liquid separator is 40-55 ℃. The ratio of the slurry flow X1 in the first reactor to the slurry flow X2 in the second reactor is 1:(1.5-9.9) based on the weight of the solid product, and the content of polymer A in the wide-distribution easy-to-process polyethylene product is 0.3-2.5 wt%.

2. The broad distribution, easily processable polyethylene of claim 1, wherein, The content of the polymer A contained in the solid phase product in the slurry in the first reactor is in the range of 0.5-8.0 wt%, the weight average molecular weight of the solid phase product in the slurry in the first reactor is in the range of 80-140 x 10 4 g / mol, the molecular weight distribution is in the range of 50-500, the content of the branch is ≤0.2 C / 1000 C, and the initial elastic modulus of the solid phase product excluding the polymer A is in the range of 0.2-0.5 MPa.

3. The broad distribution, easily processable polyethylene of claim 2, wherein, The polymer A is distributed on the surface and inside the particles of the solid product in the slurry in the first reactor, and the surface of the solid product presents a scale shape, and the polymer A is distributed between the scale-shaped lamellae, and the thickness of the scale-shaped lamellae is 10-300 nm.

4. The broad distribution, easily processable polyethylene of claim 1, wherein, The weight average molecular weight of the solid phase product in the slurry in the second reactor is 10 x 10 4 - 20 x 10 4 g / mol, and the molecular weight distribution is 10-30.

5. Use of the wide-distribution easy-to-process polyethylene according to any one of claims 1-4 in the preparation of a matte film.

6. Use according to claim 5, characterized in that, The wide-distribution easy-to-process polyethylene is mixed with polypropylene, a slip agent, and an antioxidant in a weight ratio of 1:(0.8-1.2):(0.02-0.03):(0.001-0.003), and then subjected to melt co-extrusion and two-way stretching to be used as a surface matte layer of a matte film, and the matte film has a three-layer, four-layer, five-layer, six-layer, or seven-layer structure; the surface matte layer can be a single layer or can exist as both an outer surface layer and an inner surface layer of the matte film, the matte film with a single matte layer has a haze of ≥80%, and the haze deviation of the matte film with a single matte layer on the upper and lower sides and the middle part is ≤0.3%, the matte film with a double matte layer has a haze of ≥90%, and the haze deviation of the matte film with a double matte layer on the upper and lower sides and the middle part is ≤0.5%; and the water vapor barrier rate of the matte film is ≤3.5 g / (m²·24h).

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