Preparation method of high-strength PE film based on novel catalyst

Abstract

The invention provides a preparation method of a high-strength PE film based on a novel catalyst, and relates to the field of PE films, the high-strength PE film comprises a silver ion coating, an inner layer is arranged on the outer surface of the silver ion coating, a middle layer is arranged on the outer surface of the inner layer, and an outer layer is arranged on the outer surface of the middle layer; the inner layer comprises the following raw materials: linear low-density polyethylene, low-density polyethylene and metallocene polyethylene. According to the high-strength PE film, the multi-layer co-extrusion technology is adopted, the inner layer, the middle layer and the outer layer are combined, each layer is made of polyethylene materials with different densities so as to optimize the performance, the tensile strength indexes of the PE film are that the longitudinal tensile strength is larger than 40 mpa, and the transverse tensile strength is larger than 35 mpa, the PE film has the advantages of being high in tensile strength and good in tear resistance, the requirement of packaging bags such as eight-edge sealing bags for strength can be completely met, and the high-strength PE film can be widely applied to the field of packaging bags. Due to the arrangement of the silver ion coating, when the food packaging bag is used as the food packaging bag, the side with the silver ion coating is located in the packaging bag, and the antibacterial effect can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of PE films, in particular to a method for preparing high-strength PE films based on a novel catalyst. Background Art

[0002] Currently, polyethylene film (PE film) is widely used for product packaging due to its moisture resistance, low moisture permeability, low cost, and excellent packaging performance. However, to further protect the product within and achieve better packaging results, PE film is generally required to have a certain strength. However, the tensile strength of reinforced PE film currently available on the market is generally around 25MPa. While this meets the packaging requirements of most products, it cannot meet the packaging requirements of certain specific products.

[0003] Eight-side sealed bags made of PE film have been widely used in the field of lightweight solid packaging such as candy and biscuits due to their good upright display effect. Many high-end and internet-famous ramen noodles are also packaged in eight-side sealed bags. However, if eight-side sealed bags are used as ramen bags, due to the large size of the noodles and the variety of seasonings, many food packaging factories usually have to use manual packaging. When packaging ramen, workers need to pull the opening of the eight-side sealed bag to the limit because the noodles are large. At the same time, in pursuit of efficiency, the eight-side sealed bag is easily torn, causing large losses. PE film does not have an antibacterial effect and is not strong enough, which has great limitations for its use in product packaging. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a high-strength PE film based on a novel catalyst, so as to solve the problems raised in the background technology mentioned above and overcome the technical defects thereof.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a high-strength PE film based on a new catalyst, including a silver ion coating, the outer surface of the silver ion coating is provided with an inner layer, the outer surface of the inner layer is provided with a middle layer, the outer surface of the middle layer is provided with an outer layer, the inner layer comprises the following raw materials: linear low-density polyethylene, low-density polyethylene and metallocene polyethylene, the middle layer comprises the following raw materials: high-density polyethylene and metallocene polyethylene, the outer layer comprises the following raw materials: medium-density polyethylene and metallocene polyethylene, the raw materials of at least one of the inner layer, middle layer and outer layer also include a processing aid, and the processing aid is selected from at least one of polyphthalamide, an anti-blocking agent and a masterbatch.

[0006] Preferably, the inner layer comprises the following raw materials in parts by weight: 4245 parts of linear low-density polyethylene, 2023 parts of low-density polyethylene, and 3538 parts of metallocene polyethylene.

[0007] Preferably, the middle layer comprises the following raw materials in parts by weight: 1921 parts of metallocene polyethylene and 5055 parts of high-density polyethylene.

[0008] Preferably, the outer layer comprises the following raw materials in parts by weight: 2931 parts of metallocene polyethylene and 5055 parts of medium-density polyethylene.

[0009] Preferably, the thickness of the PE film is 30-100 μm, and the thickness ratio of the inner layer, middle layer and outer layer in the PE film is 1:1.2:1.

[0010] Preferably, the density of the linear low-density polyethylene is 0.9160.920 g / cm3, and the melt index is 1.82.2 g / 10min, the density of the low-density polyethylene is 0.9220.926 g / cm3, and the melt index is 3.94.1 g / 10min, the density of the medium-density polyethylene is 0.9220.924 g / cm3, and the melt index is 0.180.22 g / 10min, and the density of the high-density polyethylene is 0.9540.958 g / cm3, and the melt index is 0.040.06 g / 10min.

[0011] Preferably, the density of the inner layer of metallocene polyethylene is 0.916-0.920 g / cm³, and the melt index is 0.9-1.1 g / 10min; the density of the middle and outer layers of metallocene polyethylene is 0.925-0.929 g / cm³, and the melt index is 1.2-1.4 g / 10min.

[0012] A method for preparing a high-strength PE film based on a novel catalyst comprises the following steps: S1. Extrusion: The material components of the inner layer, middle layer, and outer layer are mixed according to the ratio and sent to the inner layer hopper, middle layer hopper, and outer layer hopper of the extruder respectively, and the three-layer co-extrusion film blowing unit is heated in different zones.

[0013] S2. Film blowing: The three layers of fluid raw materials are fused and extruded in the extruder to form a film bubble, which is cooled and formed under cooling air at 10 to 20°C for 7580 seconds.

[0014] S3. The film bubble is flattened by a herringbone plate and evenly sprayed with a silver ion coating on its lower surface. After drying, it is sent to a traction device for traction and stretching to form a high-strength PE film.

[0015] S4. Roll up.

[0016] Preferably, the set temperatures for zone heating of the extruder are: inner layer main machine (corresponding to inner layer hopper) 210-215°C; middle layer main machine (corresponding to middle layer hopper) 195-200°C; outer layer main machine (corresponding to outer layer hopper) 210-215°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. High-strength PE film adopts multi-layer co-extrusion technology, a combination of inner layer, middle layer and outer layer. Each layer uses polyethylene materials of different densities to optimize performance. The tensile strength index of PE film is: longitudinal: >40 MPa, transverse: >35 MPa, reflecting the advantages of high tensile strength and good tear resistance, which can fully meet the strength requirements of packaging bags such as 8-side sealing bags.

[0018] 2. The setting of silver ion coating. When used as a food packaging bag, the side with silver ion coating is located inside the packaging bag, which can have an antibacterial effect.

[0019] 3. A three-layer co-extrusion film blowing machine is used for film blowing. Air is introduced from the extrusion die head for inflation and cooling. After flattening, spraying, drying, pulling and winding, a high-strength PE film is formed. The PE film proposed in the present invention has good tensile strength and tear resistance, and is suitable for preparing various packaging bag products. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 Schematically shows a process diagram for preparing a high-strength PE film according to one embodiment of the present invention; Figure 2 Schematically shows a schematic diagram of the structure of a high-strength PE film proposed according to one embodiment of the present invention; Numbers in the figure: 1, silver ion coating; 2, inner layer; 3, middle layer; 4, outer layer. DETAILED DESCRIPTION

[0021] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0022] According to one embodiment of the present invention, Figure 1-2 Shown.

[0023] Example 1: This embodiment provides a high-strength PE film based on a new catalyst, including a silver ion coating 1, an inner layer 2 is provided on the outer surface of the silver ion coating 1, a middle layer 3 is provided on the outer surface of the inner layer 2, an outer layer 4 is provided on the outer surface of the middle layer 3, the inner layer 2 includes the following raw materials: linear low-density polyethylene, low-density polyethylene and metallocene polyethylene, the middle layer 3 includes the following raw materials: high-density polyethylene and metallocene polyethylene, the outer layer 4 includes the following raw materials: medium-density polyethylene and metallocene polyethylene, the raw materials of at least one of the inner layer 2, the middle layer 3 and the outer layer 4 also include a processing aid, and the processing aid is selected from an opening agent. The high-strength PE film adopts multi-layer co-extrusion technology, a combination of the inner layer 2, the middle layer 3 and the outer layer 4, and each layer uses polyethylene materials of different densities to optimize performance. The tensile strength index of the PE film is: longitudinal: >40 MPa, transverse: >35 MPa, reflecting the advantages of high tensile strength and good tear resistance, and can fully meet the strength requirements of packaging bags such as octagonal sealed bags.

[0024] Preferably, the inner layer 2 comprises the following raw materials in parts by weight: 42 parts of linear low-density polyethylene, 20 parts of low-density polyethylene, and 35 parts of metallocene polyethylene, which are mixed to improve flexibility and heat sealing properties.

[0025] Preferably, the middle layer 3 comprises the following raw materials in parts by weight: 19 parts of metallocene polyethylene and 50 parts of high-density polyethylene to enhance mechanical strength.

[0026] Preferably, the outer layer 4 comprises the following raw materials in parts by weight: 29 parts of metallocene polyethylene and 50 parts of medium-density polyethylene to improve puncture resistance and tear resistance.

[0027] Preferably, the thickness of the PE film is 30 μm, and the thickness ratio of the inner layer 2 , the middle layer 3 and the outer layer 4 in the PE film is 1:1.2:1.

[0028] Preferably, the density of linear low density polyethylene is 0.916 g / cm3, the melt index is 1.8 g / 10 min, the density of low density polyethylene is 0.922 g / cm3, the melt index is 3.9 g / 10 min, the density of medium density polyethylene is 0.922 g / cm3, the melt index is 0.18 g / 10 min, and the density of high density polyethylene is 0.954 g / cm3, the melt index is 0.04 g / 10 min.

[0029] Preferably, the density of the metallocene polyethylene of the inner layer 2 is 0.916 g / cm³ and the melt index is 0.9 g / 10 min, and the density of the metallocene polyethylene of the middle layer 3 and the outer layer 4 is 0.925 g / cm³ and the melt index is 1.2 g / 10 min.

[0030] A method for preparing a high-strength PE film based on a novel catalyst comprises the following steps: S1. Extrusion: The material components of inner layer 2, inner layer 3, and outer layer 4 are mixed according to the ratio and respectively sent to the inner layer hopper, middle layer hopper, and outer layer hopper of the extruder, and the three-layer co-extrusion film blowing unit is heated in different zones.

[0031] S2. Film blowing: The three layers of fluid raw materials are fused and extruded in an extruder to form a film bubble. The film bubble is cooled and formed under cooling air at 10°C for 75 seconds.

[0032] S3. The film bubble is flattened by a herringbone plate and then evenly sprayed with a silver ion coating 1 on its lower surface. After drying, it is sent to a traction device for traction and stretching to form a high-strength PE film.

[0033] S4. Roll up.

[0034] The set temperatures for heating the extruder zones are: inner mainframe (corresponding to inner hopper) 210°C; middle mainframe (corresponding to middle hopper) 195°C; outer mainframe (corresponding to outer hopper) 210°C.

[0035] Example 2 This embodiment provides a high-strength PE film based on a new catalyst, characterized in that it includes a silver ion coating 1, the outer surface of the silver ion coating 1 is provided with an inner layer 2, the outer surface of the inner layer 2 is provided with a middle layer 3, the outer surface of the middle layer 3 is provided with an outer layer 4, the inner layer 2 includes the following raw materials: linear low-density polyethylene, low-density polyethylene and metallocene polyethylene, the middle layer 3 includes the following raw materials: high-density polyethylene and metallocene polyethylene, the outer layer 4 includes the following raw materials: medium-density polyethylene and metallocene polyethylene, the raw materials of at least one layer of the inner layer 2, the middle layer 3 and the outer layer 4 also include a processing aid, and the processing aid is selected from polyphthalamide. The high-strength PE film adopts multi-layer co-extrusion technology, a combination of the inner layer 2, the middle layer 3 and the outer layer 4, and each layer uses polyethylene materials of different densities to optimize performance. The tensile strength index of the PE film is: longitudinal: >40 MPa, transverse: >35 MPa, reflecting the advantages of high tensile strength and good tear resistance, and can fully meet the strength requirements of packaging bags such as octagonal sealed bags.

[0036] Preferably, the inner layer 2 comprises the following raw materials in parts by weight: 45 parts of linear low-density polyethylene, 23 parts of low-density polyethylene, and 38 parts of metallocene polyethylene, which are mixed to improve flexibility and heat sealing properties.

[0037] Preferably, the middle layer 3 comprises the following raw materials in parts by weight: 21 parts of metallocene polyethylene and 55 parts of high-density polyethylene to enhance mechanical strength.

[0038] Preferably, the outer layer 4 comprises the following raw materials in parts by weight: 31 parts of metallocene polyethylene and 55 parts of medium-density polyethylene to improve puncture resistance and tear resistance.

[0039] Preferably, the thickness of the PE film is 100 μm, and the thickness ratio of the inner layer 2 , the middle layer 3 and the outer layer 4 in the PE film is 1:1.2:1.

[0040] Preferably, the density of linear low density polyethylene is 0.920 g / cm3, the melt index is 2.2 g / 10 min, the density of low density polyethylene is 0.926 g / cm3, the melt index is 4.1 g / 10 min, the density of medium density polyethylene is 0.924 g / cm3, the melt index is 0.22 g / 10 min, and the density of high density polyethylene is 0.958 g / cm3, the melt index is 0.06 g / 10 min.

[0041] Preferably, the metallocene polyethylene of the inner layer 2 has a density of 0.920 g / cm³ and a melt index of 1.1 g / 10min, and the metallocene polyethylene of the middle layer 3 and the outer layer 4 has a density of 0.929 g / cm³ and a melt index of 1.4 g / 10min.

[0042] A method for preparing a high-strength PE film based on a novel catalyst comprises the following steps: S1. Extrusion: The material components of inner layer 2, inner layer 3, and outer layer 4 are mixed according to the ratio and respectively sent to the inner layer hopper, middle layer hopper, and outer layer hopper of the extruder, and the three-layer co-extrusion film blowing unit is heated in different zones.

[0043] S2. Film blowing: The three layers of fluid raw materials are fused and extruded in an extruder to form a film bubble. The film bubble is cooled and formed under cooling air at 20°C for 80 seconds.

[0044] S3. The film bubble is flattened by a herringbone plate and then evenly sprayed with a silver ion coating 1 on its lower surface. After drying, it is sent to a traction device for traction and stretching to form a high-strength PE film.

[0045] S4. Roll up.

[0046] The set temperatures for heating the extruder zones are: inner mainframe (corresponding to inner hopper) 215°C; middle mainframe (corresponding to middle hopper) 200°C; outer mainframe (corresponding to outer hopper) 215°C.

[0047] Example 3 This embodiment provides a high-strength PE film based on a new catalyst, including a silver ion coating 1, an inner layer 2 is provided on the outer surface of the silver ion coating 1, a middle layer 3 is provided on the outer surface of the inner layer 2, an outer layer 4 is provided on the outer surface of the middle layer 3, the inner layer 2 comprises the following raw materials: linear low-density polyethylene, low-density polyethylene and metallocene polyethylene, the middle layer 3 comprises the following raw materials: high-density polyethylene and metallocene polyethylene, the outer layer 4 comprises the following raw materials: medium-density polyethylene and metallocene polyethylene, the raw materials of at least one of the inner layer 2, the middle layer 3 and the outer layer 4 also include a processing aid, and the processing aid is selected from a masterbatch. The inner layer 2, the middle layer 3 and the outer layer 4 are combined, and each layer uses polyethylene materials of different densities to optimize performance. The tensile strength index of the PE film is: longitudinal: >40 MPa, transverse: >35 MPa, which reflects the advantages of high tensile strength and good tear resistance, and can fully meet the strength requirements of packaging bags such as octagonal sealed bags.

[0048] Preferably, the inner layer 2 comprises the following raw materials in parts by weight: 43 parts of linear low-density polyethylene, 21 parts of low-density polyethylene, and 36 parts of metallocene polyethylene, which are mixed to improve flexibility and heat sealing properties.

[0049] Preferably, the middle layer 3 comprises the following raw materials in parts by weight: 20 parts of metallocene polyethylene and 53 parts of high-density polyethylene to enhance mechanical strength.

[0050] Preferably, the outer layer 4 comprises the following raw materials in parts by weight: 30 parts of metallocene polyethylene and 53 parts of medium-density polyethylene to improve puncture resistance and tear resistance.

[0051] Preferably, the thickness of the PE film is 60 μm, and the thickness ratio of the inner layer 2 , the middle layer 3 and the outer layer 4 in the PE film is 1:1.2:1.

[0052] Preferably, the density of linear low density polyethylene is 0.918 g / cm3, the melt index is 2.0 g / 10 min, the density of low density polyethylene is 0.924 g / cm3, the melt index is 4.0 g / 10 min, the density of medium density polyethylene is 0.923 g / cm3, the melt index is 0.20 g / 10 min, and the density of high density polyethylene is 0.956 g / cm3, the melt index is 0.05 g / 10 min.

[0053] Preferably, the density of the metallocene polyethylene of the inner layer 2 is 0.918 g / cm³ and the melt index is 1.0 g / 10min, and the density of the metallocene polyethylene of the middle layer 3 and the outer layer 4 is 0.927 g / cm³ and the melt index is 1.3 g / 10min.

[0054] A method for preparing a high-strength PE film based on a novel catalyst comprises the following steps: S1. Extrusion: The material components of inner layer 2, inner layer 3, and outer layer 4 are mixed according to the ratio and respectively sent to the inner layer hopper, middle layer hopper, and outer layer hopper of the extruder, and the three-layer co-extrusion film blowing unit is heated in different zones.

[0055] S2. Film blowing: The three layers of fluid raw materials are fused and extruded in an extruder to form a film bubble. The film bubble is cooled and formed under cooling air at 20°C for 78 seconds.

[0056] S3. The film bubble is flattened by a herringbone plate and then evenly sprayed with a silver ion coating 1 on its lower surface. After drying, it is sent to a traction device for traction and stretching to form a high-strength PE film.

[0057] S4. Roll up.

[0058] The set temperatures for heating the extruder zones are: inner main unit (corresponding to inner hopper) 213°C; middle main unit (corresponding to middle hopper) 198°C; outer main unit (corresponding to outer hopper) 213°C.

[0059] Working principle: The material components of inner layer 2, inner layer 3 and outer layer 4 are mixed according to the ratio and sent to the inner layer hopper, middle layer hopper and outer layer hopper of the extruder respectively. The three-layer co-extrusion film blowing unit is heated in different zones. The fluid raw materials of the three layers are fused and extruded in the extruder, and co-extruded to form film bubbles. The film bubbles are cooled and formed under cooling air at 20°C. The film bubbles are pressed into a flat shape by a herringbone plate and the silver ion coating 1 is evenly sprayed on the lower surface. After drying, they are sent to the traction device for traction and stretching, and the formed high-strength PE film is wound.

[0060] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A high-strength PE film based on a new catalyst, characterized in that: The invention comprises a silver ion coating (1), wherein the outer surface of the silver ion coating (1) is provided with an inner layer (2), the outer surface of the inner layer (2) is provided with a middle layer (3), the outer surface of the middle layer (3) is provided with an outer layer (4), the inner layer (2) comprises the following raw materials: linear low-density polyethylene, low-density polyethylene and metallocene polyethylene, the middle layer (3) comprises the following raw materials: high-density polyethylene and metallocene polyethylene, the outer layer (4) comprises the following raw materials: medium-density polyethylene and metallocene polyethylene, and the raw materials of at least one of the inner layer (2), the middle layer (3) and the outer layer (4) further comprise a processing aid, wherein the processing aid is selected from at least one of polyphthalamide, an anti-blocking agent and a masterbatch.

2. The high-strength PE film based on the novel catalyst according to claim 1, characterized in that: The inner layer (2) comprises the following raw materials in parts by weight: 4245 parts of linear low-density polyethylene, 2023 parts of low-density polyethylene, and 3538 parts of metallocene polyethylene.

3. The high-strength PE film based on the novel catalyst according to claim 1, characterized in that: The middle layer (3) comprises the following raw materials in parts by weight: 1921 parts of metallocene polyethylene and 5055 parts of high-density polyethylene.

4. The high-strength PE film based on the novel catalyst according to claim 1, characterized in that: The outer layer (4) comprises the following raw materials in parts by weight: 2931 parts of metallocene polyethylene and 5055 parts of medium-density polyethylene.

5. The high-strength PE based on the novel catalyst according to claim 1, characterized in that: The thickness of the PE film is 30100 μm, and the thickness ratio of the inner layer (2), the middle layer (3) and the outer layer (4) in the PE film is 1:1.2:

1.

6. The high-strength PE film based on the novel catalyst according to claim 1, characterized in that: The density of the linear low-density polyethylene is 0.9160.920 g / cm 3 , the melt index is 1.82.2g / 10min, and the density of the low-density polyethylene is 0.9220.926g / cm 3 , the melt index is 3.94.1g / 10min, and the density of the medium density polyethylene is 0.9220.924g / cm 3 , the melt index is 0.180.22g / 10min, and the density of the high-density polyethylene is 0.9540.958g / cm 3 , the melt index is 0.040.06g / 10min.

7. The high-strength PE film based on the novel catalyst according to claim 1, characterized in that: The metallocene polyethylene of the inner layer (2) has a density of 0.916–0.920 g / cm³ and a melt index of 0.9–1.1 g / 10min, and the metallocene polyethylene of the middle layer (3) and the outer layer (4) has a density of 0.925–0.929 g / cm³ and a melt index of 1.2–1.4 g / 10min.

8. A method for preparing a high-strength PE film based on a novel catalyst, comprising the following steps: S1. Extrusion: The material components of the inner layer (2), inner layer (3) and outer layer (4) are mixed according to the ratio and respectively sent to the inner layer hopper, middle layer hopper and outer layer hopper of the extruder, and the three-layer co-extrusion film blowing unit is heated in different zones. S2. Film blowing: The three layers of fluid raw materials are fused and extruded in the extruder to form a film bubble, which is cooled and formed under cooling air at 10 to 20°C for 7580 seconds. S3. The film bubble is pressed into a flat shape by a herringbone plate and a silver ion coating (1) is evenly sprayed on the lower surface. After drying, it is sent to a traction device for traction and stretching to form a high-strength PE film. S4. Roll up.

9. The method for preparing a high-strength PE film based on a novel catalyst according to claim 8, characterized in that: The set temperatures for zone heating of the extruder are: inner layer main engine (corresponding to inner layer hopper) 210-215°C; middle layer main engine (corresponding to middle layer hopper) 195-200°C; outer layer main engine (corresponding to outer layer hopper) 210-215°C.

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