A master batch for solving runner lines and a preparation method and application thereof

Abstract

The present application relates to a kind of master batch for solving flow channel line and its preparation method and application.The master batch for solving flow channel line includes the following components by mass percentage: polyethylene 85%~95%, hyperbranched polyester 3%~7%, acid absorbent 1%~5% and dispersant 1%~3%;The polyethylene includes linear low density polyethylene.The master batch for solving flow channel line can eliminate flow channel line defects in the process of blowing film, improve the surface quality of film, while meeting the increasingly stringent environmental compliance requirements under the premise of avoiding the introduction of fluorine-containing substances.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a masterbatch for solving flow channel lines, its preparation method, and its application. Background Technology

[0002] In co-extrusion blown film processing, when using linear low-density polyethylene (LLDPE), its low melting point, poor dispersibility, and mismatch with the flow channels of the blown film equipment can easily lead to concentrated discharge and poor dispersion at the flow channel outlets. This results in a thicker film at the flow channel compared to other locations. After cooling by the air ring, the slower cooling rate at the thicker flow channel allows sufficient time for the molecular chains to align into regular crystalline regions, leading to high crystallinity, large crystal size, and well-developed grains. This results in decreased transparency and noticeable white streaks on the film surface, resembling the stripes of a watermelon, known as flow lines. These obvious flow line defects not only affect the product's appearance and transparency but also reduce its mechanical properties and subsequent processing adaptability. Current technologies typically use fluoropolymer processing aids (PPA) to adjust the flowability of LLDPE in the flow channels to address this issue. However, fluorinated substances can pose health and environmental hazards and fail to meet current regulations on perfluorinated and polyfluorinated compounds (PFAS).

[0003] Therefore, there is a need to develop a fluorine-free material that can improve flow line problems. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a masterbatch for resolving flow lines, its preparation method, and its application. The masterbatch for resolving flow lines can eliminate flow line defects during the blown film process and improve the surface quality of the film, while avoiding the introduction of fluorine-containing substances, and can also meet increasingly stringent environmental compliance requirements.

[0005] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a masterbatch for resolving flow lines, the masterbatch comprising, by weight percentage, the following components: 85% to 95% polyethylene (e.g., 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, or 89%, etc.), 3% to 7% hyperbranched polyester (e.g., 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, or 6.5%, etc.), 1% to 5% acid scavenger (e.g., 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, or 4.5%, etc.), and 1% to 3% dispersant (e.g., 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, or 2.8%, etc.); wherein the polyethylene comprises linear low-density polyethylene (LLDPE).

[0006] In this invention, the masterbatch for resolving flow lines is a fluorine-free functional masterbatch obtained through component design. It eliminates flow line defects at the source during the blown film process without introducing fluorine-containing substances, thereby improving film surface quality. Furthermore, it contains only carbon, hydrogen, and oxygen, and no fluorine, silicon, chlorine, or other elements, meeting increasingly stringent environmental compliance requirements such as PFAS control requirements. During the blown film process, the masterbatch for resolving flow lines exhibits characteristics of rapid migration, surface enrichment to form a lubricating layer, and continuous replenishment. In the high-shear zone of the extruder, hyperbranched polyester, due to its extremely low melt viscosity, is squeezed onto the melt surface like oil droplets. The polar ends (-OH) of the hyperbranched polyester have an affinity for the metal die surface and are firmly adsorbed onto the die wall, forming a thin (nanometer-scale), tough, low-friction coating. This allows the melt to slide on it, accelerating the flowability of linear low-density polyethylene at the outlet, enabling rapid dispersion of the linear low-density polyethylene. The thickness at the outlet is consistent with the thickness at the non-outlet, and after cooling by the air ring, the crystallization rate is consistent, preventing the formation of white flow lines. The main function of the acid scavenger is to protect the carrier resin polyethylene in the masterbatch that resolves the flow lines from degradation, thereby ensuring the quality stability of the masterbatch itself. The main function of the dispersant is to reduce the surface energy of the filler acid scavenger in the masterbatch, prevent agglomeration, and ensure that the acid scavenger is evenly distributed in the melt, thus ensuring uniform performance of the finished product.

[0007] Preferably, the linear low-density polyethylene has a melt index of 3~20 g / 10min at 190℃ and 2.16kg load, such as 5 g / 10min, 7 g / 10min, 9 g / 10min, 11 g / 10min, 13 g / 10min, 15 g / 10min, 17 g / 10min or 19 g / 10min.

[0008] Preferably, the hyperbranched polyester comprises a hydroxyl-terminated hyperbranched polyester.

[0009] Preferably, the raw materials for preparing the hyperbranched polyester include monomer A and monomer B, wherein monomer A includes a dicarboxylic acid and / or a diester, and monomer B includes a triol.

[0010] For example, the dicarboxylic acid includes adipic acid, the diester includes dimethyl succinate, and the triol includes trimethylolpropane and / or glycerol. The hyperbranched polyester is typically obtained from monomer A and monomer B through a one-step polycondensation and / or transesterification. Multiple hydroxyl groups on monomer B can react with or undergo transesterification with the carboxyl groups of monomer A, thereby continuously branching to form a three-dimensional dendritic structure.

[0011] Preferably, the hyperbranched polyester comprises the hyperbranched resin HyPer C100.

[0012] Preferably, the acid absorbent comprises molecular sieves and / or hydrotalcite.

[0013] Preferably, the dispersant comprises stearate.

[0014] In a second aspect, the present invention provides a method for preparing a masterbatch for resolving flow lines as described in the first aspect, the method comprising the following steps: mixing polyethylene, hyperbranched polyester, acid scavenger and dispersant, granulating, to obtain the masterbatch for resolving flow lines.

[0015] Preferably, the mixing includes stirring.

[0016] Preferably, the stirring speed is 200~450 rpm, such as 250 rpm, 300 rpm, 350 rpm or 400 rpm.

[0017] In this invention, the stirring speed is relatively low, which can reduce frictional heat generation, ensure uniform distribution of each component, and ensure that there are no dead corners in the mixing.

[0018] Preferably, the granulation includes granulation using a twin-screw extruder.

[0019] Preferably, the processing temperature of the twin-screw extruder is 160~190℃ (e.g., 165℃, 168℃, 171℃, 174℃, 177℃, 180℃, 183℃, 186℃ or 189℃, etc.).

[0020] Preferably, the granulation is carried out in a twin-screw extruder under vacuum conditions, wherein the vacuum degree of the vacuum is -0.08 to -0.06 MPa (e.g., -0.078 MPa, -0.076 MPa, -0.074 MPa, -0.072 MPa, -0.070 MPa, -0.068 MPa, or -0.064 MPa, etc.).

[0021] In this invention, the granulation is carried out under vacuum and degassing conditions in a twin-screw extruder, which can extract low molecular weight substances and moisture.

[0022] Preferably, the granulation includes pelletizing using a water ring die or an air-cooled die.

[0023] Preferably, the granulation process further includes centrifugal dewatering and vibrating screen sieving steps.

[0024] Thirdly, the present invention provides a blown film comprising linear low-density polyethylene and a masterbatch for resolving flow lines as described in the first aspect.

[0025] Preferably, the mass of the masterbatch for resolving flow lines as described in the first aspect in the blown film is 0.3% to 5% (e.g., 0.6%, 1.0%, 1.4%, 1.8%, 2.2%, 2.6%, 3.0%, 3.4%, 3.8%, 4.2%, or 4.6%, etc.).

[0026] Preferably, the blown film comprises an upper layer, a middle layer, and a lower layer; the upper layer comprises, by weight percentage, the following components: 95%~99.7% linear low-density polyethylene (e.g., 95.5%, 96.0%, 96.5%, 97.0%, 97.5%, 98.0%, 98.5%, 99.0%, or 99.5%, etc.) and 0.3%~5% (e.g., 0.6%, 1.0%, 1.4%, 1.8%, 2.2%, 2.6%, 3.0%, 3.4%, 3.8%, 4.2%, or 4.6%, etc.) masterbatch for resolving flow lines; the middle layer comprises, by weight percentage, the following components: 35%~59.7% linear low-density polyethylene (e.g., 38%, 41%, 44%, 47%, 50%, 53%, 56%, or 59%, etc.) and 40%~60% metallocene linear low-density polyethylene (mLLDPE) (e.g., 42%, 44%). The lower layer comprises, by mass percentage, 55% to 79.7% (e.g., 58%, 61%, 64%, 67%, 70%, 73%, or 76%) of metallocene linear low-density polyethylene, 20% to 40% (e.g., 23%, 26%, 29%, 32%, 35%, or 38%) of linear low-density polyethylene, and 0.3% to 5% (e.g., 0.6%, 1.0%, 1.4%, 1.8%, 2.2%, 2.6%, 3.0%, 3.4%, 3.8%, 4.2%, or 4.6%) of masterbatch for resolving flow lines.

[0027] In this invention, each layer of the blown film prepared by multi-layer co-extrusion blown film contains a masterbatch for resolving flow lines. The masterbatch for resolving flow lines forms a dynamic lubricating layer between the melt and the die metal wall, effectively reducing the frictional resistance between the melt and the metal interface, making the melt flow more uniform, thereby suppressing the generation of flow lines from the root. The masterbatch for resolving flow lines contains a low amount of hyperbranched polyester, which is constantly being washed away by the melt. It needs to continuously migrate from the interior of the melt to the surface, and the hyperbranched structure of the hyperbranched polyester ensures that this migration speed can be achieved.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects: The masterbatch for resolving flow lines described in this invention eliminates flow line defects during the blown film process while avoiding the introduction of fluorine-containing substances, thus improving the surface quality of the blown film and meeting increasingly stringent environmental compliance requirements. Blown films prepared using multi-layer co-extrusion blown film, with the masterbatch for resolving flow lines added to each layer of the raw material, exhibit tensile strength ≥25 MPa, composite peel strength ≥5 N / 15 mm, and flow line elimination time ≤25 min. Preferably, the prepared blown film has a tensile strength ≥44 MPa, a composite peel strength ≥11 N / 15 mm, and a flow line elimination time ≤15 min. Attached Figure Description

[0029] Figure 1 and Figure 2 The image shows a physical picture of the blown film prepared in Example 1. Figure 3 and Figure 4 This is a photograph of the blown film prepared in Comparative Example 3. Detailed Implementation

[0030] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0031] Unless otherwise specified, the materials and equipment involved in the following detailed embodiments are all conventional materials and equipment in the art and will not affect the technical effects of the present invention.

[0032] Example 1 This embodiment provides a masterbatch for solving flow lines, its preparation method, and a blown film. The masterbatch for solving flow lines comprises the following components by mass percentage: 85% polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load), 7% hyperbranched polyester (hyperbranched resin HyPer C100), 5% acid scavenger (molecular sieve, model CZ-A00X10B, manufactured by Jiangsu Juqian New Material Technology Co., Ltd.), and 3% dispersant (magnesium stearate).

[0033] The preparation method includes the following steps: polyethylene, hyperbranched polyester, acid scavenger, and dispersant are mixed by stirring at 300 rpm for 15 min, and then added to a twin-screw extruder for granulation. The twin-screw extruder has a screw diameter of 70 mm, an aspect ratio of 38, and a rotation speed of 500 rpm. The temperatures of the first, second, third, fourth, fifth, sixth, and seventh zones of the twin-screw extruder are 170℃, 185℃, 185℃, 180℃, 175℃, and 165℃, respectively. Granulation is carried out under vacuum conditions in the twin-screw extruder, with a vacuum degree of -0.07 MPa. After extrusion by the twin-screw extruder, the pellets are cut into pellets using a water ring die, and then centrifuged for dehydration and sieved by a vibrating screen to obtain the masterbatch that solves the flow channel line problem.

[0034] The blown film comprises an upper layer, a middle layer, and a lower layer stacked sequentially, with a thickness ratio of 1:2:1. The upper layer is prepared from raw materials comprising, by mass percentage: 98% linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load) and 2% of the aforementioned masterbatch for resolving flow lines. The middle layer is prepared from raw materials comprising, by mass percentage: 49.7% linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load), 50% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), and 0.3% of the aforementioned masterbatch for resolving flow lines. The lower layer is prepared from raw materials comprising, by mass percentage: 67% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), 50% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), and 2% of the aforementioned masterbatch for resolving flow lines. The melt index at a load of 3 g / 10 min is 30%, and the masterbatch for solving the flow line problem is 3%.

[0035] The blown film is prepared by the following method: the raw materials for the upper, middle and lower layers are blown by a multi-layer co-extrusion blow molding machine. The time from the start of blow molding to the stable appearance of the film (forming a stable state without flow lines or with slight flow lines) is recorded as the flow line elimination time. Then, blow molding continues to obtain the blown film.

[0036] Example 2 This embodiment provides a masterbatch for solving flow lines, its preparation method, and a blown film. The masterbatch for solving flow lines includes the following components by mass percentage: 89% polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load), 7% hyperbranched polyester (hyperbranched resin HyPer C100), 2% acid scavenger (molecular sieve, model CZ-A00X10B, manufactured by Jiangsu Juqian New Material Technology Co., Ltd.), and 2% dispersant (magnesium stearate).

[0037] The preparation method includes the following steps: polyethylene, hyperbranched polyester, acid scavenger, and dispersant are mixed by stirring at 200 rpm for 20 min, and then added to a twin-screw extruder for granulation. The twin-screw extruder has a screw diameter of 70 mm, an aspect ratio of 38, and a rotation speed of 500 rpm. The temperatures of the first, second, third, fourth, fifth, sixth, and seventh zones of the twin-screw extruder are 170℃, 185℃, 185℃, 180℃, 175℃, and 165℃, respectively. Granulation is carried out under vacuum conditions in the twin-screw extruder, with a vacuum degree of -0.08 MPa. After extrusion by the twin-screw extruder, the pellets are cut into pellets using a water ring die, and then centrifuged for dehydration and sieved by a vibrating screen to obtain the masterbatch that solves the flow channel line problem.

[0038] The blown film comprises an upper layer, a middle layer, and a lower layer stacked sequentially, with a thickness ratio of 1:2:1. The upper layer is prepared from raw materials comprising, by mass percentage: 98% linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load) and 2% of the aforementioned masterbatch for resolving flow lines. The middle layer is prepared from raw materials comprising, by mass percentage: 49.7% linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load), 50% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), and 0.3% of the aforementioned masterbatch for resolving flow lines. The lower layer is prepared from raw materials comprising, by mass percentage: 67% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), 50% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), and 2% of the aforementioned masterbatch for resolving flow lines. The melt index at a load of 3 g / 10 min is 30%, and the masterbatch for solving the flow line problem is 3%.

[0039] The blown film is prepared by the following method: the raw materials for the upper, middle and lower layers are blown by a multi-layer co-extrusion blow molding machine. The time from the start of blow molding to the stable appearance of the film (forming a stable state without flow lines or with slight flow lines) is recorded as the flow line elimination time. Then, blow molding continues to obtain the blown film.

[0040] Example 3 This embodiment provides a masterbatch for solving flow lines, its preparation method, and a blown film. The masterbatch for solving flow lines includes the following components by mass percentage: 91% polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load), 7% hyperbranched polyester (hyperbranched resin HyPer C100), 1% acid scavenger (molecular sieve, CZ-A00X10B, manufactured by Jiangsu Juqian New Material Technology Co., Ltd.), and 1% dispersant (magnesium stearate).

[0041] The preparation method includes the following steps: polyethylene, hyperbranched polyester, acid scavenger, and dispersant are mixed by stirring at 450 rpm for 10 min, and then added to a twin-screw extruder for granulation. The twin-screw extruder has a screw diameter of 70 mm, an aspect ratio of 38, and a rotation speed of 500 rpm. The temperatures of the first, second, third, fourth, fifth, sixth, and seventh zones of the twin-screw extruder are 170℃, 185℃, 185℃, 180℃, 175℃, and 165℃, respectively. Granulation is carried out under vacuum conditions in the twin-screw extruder, with a vacuum degree of -0.06 MPa. After extrusion by the twin-screw extruder, the pellets are cut into pellets using a water ring die, and then centrifuged for dehydration and sieved by a vibrating screen to obtain the masterbatch that solves the flow channel line problem.

[0042] The blown film comprises an upper layer, a middle layer, and a lower layer stacked sequentially, with a thickness ratio of 1:2:1. The upper layer is prepared from raw materials comprising, by mass percentage: 98% linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load) and 2% of the aforementioned masterbatch for resolving flow lines. The middle layer is prepared from raw materials comprising, by mass percentage: 49.7% linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load), 50% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), and 0.3% of the aforementioned masterbatch for resolving flow lines. The lower layer is prepared from raw materials comprising, by mass percentage: 67% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), 50% metallocene linear low-density polyethylene (melt index of 2 g / 10min at 190°C and 2.16 kg load), and 2% of the aforementioned masterbatch for resolving flow lines. The melt index at a load of 3 g / 10 min is 30%, and the masterbatch for solving the flow line problem is 3%.

[0043] The blown film is prepared by the following method: the raw materials for the upper, middle and lower layers are blown by a multi-layer co-extrusion blow molding machine. The time from the start of blow molding to the stable appearance of the film (forming a stable state without flow lines or with slight flow lines) is recorded as the flow line elimination time. Then, blow molding continues to obtain the blown film.

[0044] Example 4 This embodiment provides a masterbatch for solving flow lines, its preparation method, and a blown film. The difference between this embodiment and Embodiment 1 is that the mass percentage of hyperbranched polyester in the masterbatch for solving flow lines is adjusted to 5%, and the mass percentage of polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load) is adjusted to 87%. Other conditions are the same as in Embodiment 1.

[0045] Example 5 This embodiment provides a masterbatch for solving flow lines, its preparation method, and a blown film. The difference between this embodiment and Embodiment 1 is that the mass percentage of hyperbranched polyester in the masterbatch for solving flow lines is adjusted to 3%, and the mass percentage of polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load) is adjusted to 89%. Other conditions are the same as in Embodiment 1.

[0046] Comparative Example 1 This comparative example provides a masterbatch for solving flow lines, its preparation method, and a blown film. The difference between this example and Example 1 is that the mass percentage of hyperbranched polyester in the masterbatch for solving flow lines is adjusted to 9%, and the mass percentage of polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load) is adjusted to 83%. Other conditions are the same as in Example 1.

[0047] Comparative Example 2 This comparative example provides a masterbatch for solving flow lines, its preparation method, and a blown film. The difference between this example and Example 1 is that the mass percentage of hyperbranched polyester in the masterbatch for solving flow lines is adjusted to 1%, and the mass percentage of polyethylene (linear low-density polyethylene with a melt index of 3 g / 10min at 190°C and 2.16 kg load) is adjusted to 91%. Other conditions are the same as in Example 1.

[0048] Comparative Example 3 This comparative example provides a blown film, which differs from Example 1 in that the blown film does not contain masterbatch for resolving flow lines, while other conditions are the same as in Example 1.

[0049] Comparative Example 4 This comparative example provides a masterbatch for resolving flow lines, its preparation method, and a blown film. The difference between this example and Example 1 is that the linear low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load) in the masterbatch for resolving flow lines is replaced with the same mass of low-density polyethylene (melt index of 3 g / 10min at 190°C and 2.16 kg load), while other conditions are the same as in Example 1.

[0050] Comparative Example 5 This comparative example provides a blown film, which differs from Example 1 in that the masterbatch for solving the flow lines in the blown film is replaced with the same mass of fluoropolymer (model PAA 2800S, manufactured by Shanghai Luju Chemical), while other conditions are the same as in Example 1.

[0051] The blown films provided in Examples 1-5 and Comparative Examples 1-5 were subjected to the following performance tests.

[0052] (1) Change time: Record the time for eliminating flow lines during blown film preparation. Each sample was tested three times and the average value was taken. If the average time for eliminating flow lines was ≥10 min and <15 min, the change time was recorded as 10-15 min; if the average time for eliminating flow lines was ≥15 min and <20 min, the change time was recorded as 15-20 min; if the average time for eliminating flow lines was ≥20 min and <25 min, the change time was recorded as 20-25 min; if the average time for eliminating flow lines was ≥25 min and <30 min, the change time was recorded as 25-30 min; if the average time for eliminating flow lines was ≥30 min and <50 min, the change time was recorded as 30-50 min; if the average time for eliminating flow lines was ≥50 min and <70 min, the change time was recorded as 50-70 min; if the average time for eliminating flow lines was ≥70 min and <90 min, the change time was recorded as 70-90 min.

[0053] The change time reflects the ability to eliminate flow line defects during the blown film process; the shorter the change time, the stronger the ability to eliminate flow line defects during the blown film process.

[0054] (2) Appearance: Observe whether the blown film prepared after the film appearance is stable has flow lines.

[0055] (3) Tensile strength: The test shall be conducted in accordance with the provisions of GB / T 1040.3-2006. The specimen shall be a long strip specimen with a length of 150 mm and a width of 10 mm. The distance between the clamps shall be 50 mm ± 1 mm. The tensile speed shall be 500 mm / min ± 50 mm / min.

[0056] (4) Composite peel strength: Tested according to GB / T 8808-1988. The specimen is a strip-shaped specimen with a length of 200 mm and a width of 15 mm. The distance between the clamps is 50 mm ± 1 mm, and the tensile speed is 300 mm / min ± 50 mm / min.

[0057] The test results are shown in Table 1 below.

[0058] Table 1 In Table 1, “ / ” indicates that a blown film with a stable film appearance and no or slight flow lines was not obtained within a 90-minute blow molding time.

[0059] According to the test results in Table 1, the blown films prepared in Examples 1-5 have no flow lines in appearance, change rapidly, and meet the mechanical properties requirements, namely, tensile strength ≥ 40.1 MPa (far exceeding the standard requirement of 25 MPa) and composite peel strength ≥ 7.8 N / 15 mm (higher than the standard of 5 N / 15 mm). The masterbatches prepared in Examples 1-5 that solve the flow line problem can achieve similar or even better effects than PPA fluoropolymer processing aids (Comparative Example 5), without the need to introduce fluorinated substances.

[0060] The masterbatch for eliminating flow lines provided in Examples 1-3 contains 7% hyperbranched polyester by mass, and the blown film prepared with this masterbatch eliminates flow lines in 10-15 min. The masterbatch for eliminating flow lines provided in Example 4 contains 5% hyperbranched polyester by mass, and the blown film prepared with this masterbatch eliminates flow lines in 15-20 min. The masterbatch for eliminating flow lines provided in Example 5 contains 3% hyperbranched polyester by mass, and the blown film prepared with this masterbatch eliminates flow lines in 20-25 min. When the mass percentage of hyperbranched polyester in the masterbatch for eliminating flow lines decreases, the change time increases.

[0061] The masterbatch for solving the flow channel problem provided in Example 1 has a linear low-density polyethylene (LLDPE) content of 85%, a tensile strength of 40.1 MPa, and a composite peel strength of 7.8 N / 15 mm. The masterbatch for solving the flow channel problem provided in Example 4 has a LLDPE content of 87%, a tensile strength of 42.2 MPa, and a composite peel strength of 9.6 N / 15 mm. The masterbatches for solving the flow channel problem provided in Examples 2 and 5 have a LLDPE content of 89%, tensile strengths of 44.2 MPa and 44.0 MPa, and composite peel strengths of 11.9 N / 15 mm and 12.1 N / 15 mm, respectively. The masterbatch for solving the flow channel problem provided in Example 3 has a LLDPE content of 91%, a tensile strength of 46.6 MPa, and a composite peel strength of 13.8 N / 15 mm. As the LLDPE content in the masterbatch for solving the flow channel problem increases, both the tensile strength and the composite peel strength increase.

[0062] Figure 1 and Figure 2 The image shows the actual blown film prepared in Example 1, which has no flow lines. Figure 3 and Figure 4 The image shows a physical picture of the blown film prepared in Comparative Example 3, in which obvious flow lines are visible.

[0063] Compared to Example 1, if the mass percentage of hyperbranched polyester in the masterbatch that solves the flow line problem is too high (Comparative Example 1), the blown film will have no flow lines and the change time will be very fast (5-10 min). However, the blown film will be too transparent, and the composite peel strength (from 7.8 N / 15 mm to 6.2 N / 15 mm) and tensile strength (from 40.1 MPa to 37.9 MPa) will both decrease significantly.

[0064] Compared to Example 1, if the mass percentage of hyperbranched polyester in the masterbatch used to solve the flow lines is too low (Comparative Example 2), slight flow lines appear in the blown film, and the change time is significantly prolonged (from 10-15 min to 70-90 min), resulting in more material waste.

[0065] Compared to Example 1, if the blown film does not contain the masterbatch for resolving flow lines (Comparative Example 3), then the blown film exhibits obvious flow lines and has lower tensile strength and composite peel strength.

[0066] Compared with Example 1, if the linear low-density polyethylene in the masterbatch for solving the flow lines is replaced with the same mass of low-density polyethylene (Comparative Example 4), the blown film has no flow lines and the change time is faster, but the tensile strength and composite peel strength are significantly lower and do not meet the standards of tensile strength ≥25MPa and composite peel strength ≥5 N / 15mm.

[0067] Compared with Example 1, if a fluoropolymer (Comparative Example 5) is added to the blown film, the blown film has no flow lines, the change time is longer, which is 25-30 minutes, and the tensile strength and composite peel strength both meet the standards of tensile strength ≥25MPa and composite peel strength ≥5 N / 15mm. However, the introduction of fluorine-containing substances can easily cause harm to human health and the environment.

[0068] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A masterbatch for solving flow channel lines, characterized in that, The masterbatch for resolving flow lines comprises the following components by mass percentage: 85%~95% polyethylene, 3%~7% hyperbranched polyester, 1%~5% acid scavenger, and 1%~3% dispersant; The polyethylene includes linear low-density polyethylene.

2. The masterbatch for solving flow channel lines according to claim 1, characterized in that, The hyperbranched polyester includes hydroxyl-terminated hyperbranched polyester.

3. The masterbatch for solving flow channel lines according to claim 1 or 2, characterized in that, The raw materials for preparing the hyperbranched polyester include monomer A and monomer B, wherein monomer A includes a dicarboxylic acid and / or a diester, and monomer B includes a triol.

4. The masterbatch for solving flow lines according to any one of claims 1 to 3, characterized in that, The hyperbranched polyester includes the hyperbranched resin HyPer C100.

5. The masterbatch for solving flow lines according to any one of claims 1 to 4, characterized in that, The acid absorbent includes molecular sieves and / or hydrotalcite.

6. The masterbatch for solving flow lines according to any one of claims 1 to 5, characterized in that, The dispersant includes stearate.

7. A method for preparing a masterbatch for solving flow channel lines as described in any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: mixing polyethylene, hyperbranched polyester, acid absorber and dispersant, granulating, to obtain the masterbatch that solves the flow channel line.

8. The preparation method according to claim 7, characterized in that, The mixing includes stirring and mixing; Preferably, the granulation includes granulation using a twin-screw extruder; Preferably, the processing temperature of the twin-screw extruder is 160~190℃.

9. A blown film, characterized in that, The blown film comprises linear low-density polyethylene and the masterbatch for resolving flow lines as described in any one of claims 1 to 6.

10. The blown film according to claim 9, characterized in that, The mass of the masterbatch for solving flow lines as described in any one of claims 1 to 6 in the blown film is 0.3% to 5%.

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