A film and a process for its production

Abstract

The application relates to the technical field of plastic film, and discloses a PE film and a production process thereof, the PE film comprises, from outside to inside, an outer layer A, an intermediate layer B and an outer layer C; the outer layer A comprises the following raw materials in parts by weight: 80-100 parts of flexible polypropylene, 1-3 parts of polyolefin elastomer and 3-6 parts of anti-ultraviolet anti-aging agent; the intermediate layer B comprises the following raw materials in parts by weight: 80-100 parts of high-strength polyethylene, 1-5 parts of polyolefin elastomer and 10-15 parts of a colorant; and the outer layer C comprises the following raw materials in parts by weight: 80-100 parts of flexible polypropylene, 1-5 parts of polyolefin elastomer and 3-6 parts of anti-ultraviolet anti-aging agent. Through the technical scheme, the problem that the co-extrusion film in the multilayer PE film in the prior art cannot be completely separated and has low strength is solved.

Description

Technical Field

[0001] This invention relates to the field of plastic film technology, specifically to a film and its manufacturing process. Background Technology

[0002] Plastic films are made from PVC, PE, PP, and other resins. Among them, PE film is the most common and widely used plastic packaging material. It is generally made by co-extrusion of three layers: an outer layer, a middle layer, and an inner layer. PE film has advantages such as good chemical stability, resistance to acid and alkali corrosion at room temperature, softness, transparency, good heat-sealing properties, impact resistance, tear resistance, durability, and high shrinkage rate. It is widely used in film products, daily necessities, and food packaging bags. PE film also has good moisture resistance and low moisture permeability. However, ordinary PE film has defects such as linear molecular chains, low density, easy permeability of oil molecules, and low strength. Therefore, in order to solve the defect of low strength of multilayer co-extruded PE films in existing technologies, it is extremely important to prepare a high-strength PE film and develop its production process. Summary of the Invention

[0003] This invention proposes a thin film and its manufacturing process, which solves the problem of low strength of multilayer thin films in related technologies.

[0004] The technical solution of the present invention is as follows:

[0005] This invention proposes a thin film comprising, from the outside to the inside, an outer layer A, an intermediate layer B, and an outer layer C, wherein the outer layer A comprises the following raw materials in parts by weight:

[0006] 80-100 parts flexible polypropylene, 1-3 parts polyolefin elastomer, 3-6 parts UV-resistant anti-aging agent;

[0007] The intermediate layer B comprises the following raw materials in parts by weight:

[0008] 80-100 parts high-strength polyethylene, 1-5 parts polyolefin elastomer, 10-15 parts colorant;

[0009] The outer layer C comprises the following raw materials in parts by weight:

[0010] 80-100 parts flexible polypropylene, 1-5 parts polyolefin elastomer, 3-6 parts UV resistant anti-aging agent.

[0011] As a further technical solution, the raw material mass ratio of the outer layer A, the middle layer B, and the outer layer C is 3:8:3.

[0012] The flexible polypropylene grades in outer layer A and outer layer C are each independently 208CF Borouge, and the polyolefin elastomer grades in outer layer A and outer layer C are each independently 6102FL Exxon.

[0013] As a further technical solution, the high-strength polyethylene in the intermediate layer B is of grade ST50 Dow, and the polyolefin elastomer in the intermediate layer B is of grade 7266 Dow.

[0014] As a further technical solution, the anti-ultraviolet anti-aging agent is one or more of p-nitroaniline, N-phenyl-α-naphthylamine, and N-phenyl-N-cyclohexyl-p-phenylenediamine.

[0015] As a further technical solution, the colorant is one or both of black masterbatch and titanium dioxide.

[0016] The present invention also proposes a manufacturing process for the aforementioned thin film, comprising the following steps:

[0017] S1. Mix the raw materials in outer layer A, melt and extrude to obtain outer layer A extrusion material;

[0018] S2. Mix the raw materials in the intermediate layer B, melt and extrude to obtain the intermediate layer B extrusion material;

[0019] S3. Mix the raw materials in the outer layer C, melt and extrude to obtain the outer layer C extrusion material;

[0020] S4. The outer layer A extrusion material, the middle layer B extrusion material, and the outer layer C extrusion material are filtered through a filter screen, connected, and distributed into three layers A, B, and C by a distributor. The mixture is then formed through a die head, cooled, and dried to obtain a film.

[0021] As a further technical solution, a desiccant is added in steps S2 and S3. The amount of desiccant added in step S2 accounts for 0.5% to 1% of the total mass of the intermediate layer B raw material, and the amount of desiccant added in step S3 accounts for 0.5% to 1% of the total mass of the outer layer C raw material. The desiccant is alumina or silica gel.

[0022] As a further technical solution, in step S1, when the outer layer A is melt-extruded, the barrel temperature is 165~235℃; in step S2, when the middle layer B is melt-extruded, the barrel temperature is 170~205℃; and in step S3, when the outer layer C is melt-extruded, the barrel temperature is 170~245℃.

[0023] As a further technical solution, during the melt extrusion of the outer layer A in step S1, the barrel temperature is divided into zones 1 to 6, with temperatures as follows: Zone 1: 165℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 235℃, Zone 6: 235℃; during the melt extrusion of the middle layer B in step S2, the barrel temperature is divided into zones 1 to 7, with temperatures as follows: Zone 1: 175℃, Zone 2: 185℃, Zone 3: 195℃, Zone 4: 205℃. In step S3, during the melt extrusion of the outer layer C, the barrel temperature is divided into zones 1 to 7, with temperatures as follows: Zone 1: 175℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 245℃, Zone 6: 245℃, Zone 7: 245℃. In step S4, the die distributor temperature is divided into zones 1 to 13, and the temperature of each of zones 1 to 13 is 285℃.

[0024] The working principle and beneficial effects of this invention are as follows:

[0025] 1. In this invention, the film is configured from the outside to the inside as an outer layer A, an intermediate layer B, and an outer layer C. The outer layers A and C are made of flexible polypropylene as the main material, with added polyolefin elastomer and UV-resistant antioxidant. The intermediate layer is made of high-strength polyethylene as the main material, with added polyolefin elastomer and colorant. The raw materials of the outer layers A and C are different from those of the intermediate layer B, which allows the three-layer co-extruded film to be completely separated, significantly improving the strength of the film.

[0026] 2. In this invention, the raw material mass ratio of outer layer A, middle layer B, and outer layer C is set to 3:8:3, which further improves the strength of the film.

[0027] 3. In the present invention, in the film production process, the outer layer A, the middle layer B, and the outer layer C are melt-extruded separately, and the crystallization point of the process is controlled by controlling the temperature of the outer layer A, the middle layer B, and the outer layer C, which further improves the strength of the film. At the same time, it can also completely separate the three co-extruded films. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A thin film includes, from the outside in, an outer layer A, an intermediate layer B, and an outer layer C, wherein the outer layer A is made of the following material:

[0031] 80 parts flexible polypropylene, 1 part polyolefin elastomer, 3 parts p-nitroaniline;

[0032] The raw materials for the intermediate layer B are: 80 parts high-strength polyethylene, 1 part polyolefin elastomer, and 10 parts black masterbatch.

[0033] The raw materials for outer layer C are: 80 parts flexible polypropylene, 1 part polyolefin elastomer, and 3 parts p-nitroaniline;

[0034] The raw material mass ratio of outer layer A, middle layer B, and outer layer C is 3:8:3;

[0035] The thin film production process is as follows:

[0036] S1. Mix the raw materials in outer layer A and melt-extrude them using screw extruder A. The barrel temperature is divided into 6 zones, with the following temperatures in sequence: Zone 1: 165℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 235℃, Zone 6: 235℃; to obtain the outer layer A extruded material.

[0037] S2. Mix the raw materials in the intermediate layer B, add 0.5 parts of alumina, and melt extrude using screw extruder B. The barrel temperature is divided into 1 to 7 zones, with the following temperatures in sequence: Zone 1: 175℃, Zone 2: 185℃, Zone 3: 195℃, Zone 4: 205℃, Zone 5: 205℃, Zone 6: 205℃, Zone 7: 205℃, to obtain the intermediate layer B extrusion material.

[0038] S3. Mix the raw materials in the outer layer C, add 0.4 parts of alumina, and melt extrude using a screw extruder C. The barrel temperature is divided into 1 to 7 zones, with the following temperatures in sequence: Zone 1: 175℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 245℃, Zone 6: 245℃, Zone 7: 245℃, to obtain the outer layer C extruded material.

[0039] S4. Filter the outer layer A extrusion material, the middle layer B extrusion material, and the outer layer C extrusion material through a filter screen, connect them, divide the die head distributor temperature into 1~13 zones, and distribute them into three layers A, B, and C at 285℃. Form through the die head, cool, and dry to obtain a film.

[0040] Example 2

[0041] A thin film includes, from the outside in, an outer layer A, an intermediate layer B, and an outer layer C, wherein the outer layer A is made of the following material:

[0042] 90 parts flexible polypropylene, 2 parts polyolefin elastomer, 4 parts p-nitroaniline;

[0043] The raw materials for the intermediate layer B are: 100 parts high-strength polyethylene, 5 parts polyolefin elastomer, and 13 parts black masterbatch.

[0044] The raw materials for outer layer C are: 90 parts flexible polypropylene, 5 parts polyolefin elastomer, and 5 parts p-nitroaniline;

[0045] The raw material mass ratio of outer layer A, middle layer B, and outer layer C is 3:8:3;

[0046] The thin film production process is as follows:

[0047] S1. Mix the raw materials in outer layer A and melt-extrude them using screw extruder A. The barrel temperature is divided into 6 zones, with the following temperatures in sequence: Zone 1: 165℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 235℃, Zone 6: 235℃; to obtain the outer layer A extruded material.

[0048] S2. Mix the raw materials in the intermediate layer B, add 1.1 parts of silicone, and melt extrude using screw extruder B. The barrel temperature is divided into 1 to 7 zones, with the following temperatures in sequence: Zone 1: 175℃, Zone 2: 185℃, Zone 3: 195℃, Zone 4: 205℃, Zone 5: 205℃, Zone 6: 205℃, Zone 7: 205℃, to obtain the intermediate layer B extrusion material.

[0049] S3. Mix the raw materials in the outer layer C, add 0.97 parts of silicone, and melt extrude using a screw extruder C. The barrel temperature is divided into 1 to 7 zones, with the following temperatures in sequence: Zone 1: 175℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 245℃, Zone 6: 245℃, Zone 7: 245℃, to obtain the outer layer C extrusion material.

[0050] S4. The outer layer A extruded material, the middle layer B extruded material, and the outer layer C extruded material are filtered through a filter screen. The temperature of the die head distributor is divided into 1~13 zones. The material is distributed into three layers A, B, and C by the distributor at 285℃. The material is formed by the die head, cooled, and dried to obtain a film.

[0051] Example 3

[0052] A thin film includes, from the outside in, an outer layer A, an intermediate layer B, and an outer layer C, wherein the outer layer A is made of the following material:

[0053] 100 parts flexible polypropylene, 3 parts polyolefin elastomer, 6 parts p-nitroaniline;

[0054] The raw materials for the intermediate layer B are: 95 parts high-strength polyethylene, 4 parts polyolefin elastomer, and 15 parts black masterbatch.

[0055] The raw materials for outer layer C are: 100 parts flexible polypropylene, 3 parts polyolefin elastomer, and 6 parts p-nitroaniline;

[0056] The raw material mass ratio of outer layer A, middle layer B, and outer layer C is 3:8:3;

[0057] The thin film production process is as follows:

[0058] S1. Mix the raw materials in outer layer A and melt-extrude them using screw extruder A. The barrel temperature is divided into 6 zones, with the following temperatures in sequence: Zone 1: 165℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 235℃, Zone 6: 235℃; to obtain the outer layer A extruded material.

[0059] S2. Mix the raw materials in the intermediate layer B, add 1.2 parts of alumina, and melt extrude using screw extruder B. The barrel temperature is divided into 1 to 7 zones, with the following temperatures in sequence: Zone 1: 175℃, Zone 2: 185℃, Zone 3: 195℃, Zone 4: 205℃, Zone 5: 205℃, Zone 6: 205℃, Zone 7: 205℃, to obtain the intermediate layer B extrusion material.

[0060] S3. Mix the raw materials in the outer layer C, add 1.1 parts of alumina, and melt extrude using a screw extruder C. The barrel temperature is divided into 1 to 7 zones, with the following temperatures in sequence: Zone 1: 175℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 245℃, Zone 6: 245℃, Zone 7: 245℃, to obtain the outer layer C extrusion material.

[0061] S4. The outer layer A extruded material, the middle layer B extruded material, and the outer layer C extruded material are filtered through a filter screen. The temperature of the die head distributor is divided into 1~13 zones. The material is distributed into three layers A, B, and C by the distributor at 285℃. The material is formed by the die head, cooled, and dried to obtain a film.

[0062] Example 4

[0063] The difference between this embodiment and Embodiment 1 lies only in the film production process. The barrel temperature of the outer layer A is divided into zones 1 to 6, with temperatures of 150°C, 180°C, 200°C, 210°C, 210°C, and 210°C respectively, resulting in the outer layer A extruded material. The barrel temperature of the middle layer B is divided into zones 1 to 7, with temperatures of 150°C, 160°C, 170°C, 180°C, 180°C, 180°C, 180°C, and 180°C respectively, resulting in the middle layer B extruded material. The barrel temperature of the outer layer C is divided into zones 1 to 7, with temperatures of 150°C, 180°C, 200°C, 210°C, 220°C, 220°C, and 220°C respectively, resulting in the outer layer C extruded material.

[0064] Example 5

[0065] The difference between this embodiment and Embodiment 1 lies only in the film production process. The barrel temperature of the outer layer A is divided into zones 1 to 6, with temperatures of 190°C, 220°C, 240°C, 250°C, 250°C, and 250°C respectively, resulting in the outer layer A extruded material. The barrel temperature of the middle layer B is divided into zones 1 to 7, with temperatures of 190°C, 200°C, 210°C, 220°C, 220°C, 220°C, and 220°C respectively, resulting in the middle layer B extruded material. The barrel temperature of the outer layer C is divided into zones 1 to 7, with temperatures of 190°C, 220°C, 240°C, 250°C, 260°C, 260°C, and 260°C respectively, resulting in the outer layer C extruded material.

[0066] Example 6

[0067] The only difference between this embodiment and Embodiment 1 is that the raw material mass ratio of outer layer A, middle layer B, and outer layer C is 1:5:1.

[0068] Comparative Example 1

[0069] The difference between this comparative example and Example 1 is that the raw materials for the intermediate layer B are: 80 parts flexible polypropylene, 1 part polyolefin elastomer, and 3 parts p-nitroaniline.

[0070] Comparative Example 2

[0071] The only difference between this comparative example and Example 1 is that the raw materials for the outer layer C are: 80 parts high-strength polyethylene, 1 part polyolefin elastomer, and 10 parts black masterbatch.

[0072] Comparative Example 3

[0073] The only difference between this comparative example and Example 1 is that the raw materials for layers A, B, and C in the film are:

[0074] Layer A: 80 parts flexible polypropylene, 10 parts high-strength polyethylene, 5 parts polyolefin elastomer, 3 parts p-nitroaniline;

[0075] Layer B: 90 parts high-strength polyethylene, 1 part polyolefin elastomer, 10 parts black masterbatch;

[0076] Layer C: 80 parts flexible polypropylene, 10 parts high-strength polyethylene, 5 parts polyolefin elastomer, and 3 parts p-nitroaniline.

[0077] The sources of raw materials for Examples 1-6 and Comparative Examples 1-3 are shown in Table 1:

[0078] Table 1. Sources of raw materials in Examples 1-6 and Comparative Examples 1-3

[0079]

[0080] The films prepared in Examples 1-6 and Comparative Examples 1-3 were tested for longitudinal tensile strength, transverse tensile strength, and longitudinal tensile properties according to GB / T 1040.3-2006. The test results are shown in Table 2.

[0081] Table 2. Thin Film Performance Test Results

[0082]

[0083] Based on the data from Example 1 and Comparative Examples 1-2, it can be seen that the raw materials of the outer layers A and C of the film prepared by the present invention are different from those of the intermediate layer B, which improves the tensile strength and elongation at break of the film, thereby significantly improving the strength of the film.

[0084] According to the data from Examples 1 and 6, it can be seen that when the raw material mass ratio of the outer layer A, the middle layer B, and the outer layer C of the film is set to 3:8:3, the strength of the film is further improved.

[0085] Based on the data from Examples 1 and 4-5, it can be seen that the present invention further improves the strength of the film by controlling the process temperature of the outer layer A, the middle layer B, and the outer layer C.

[0086] Films were prepared using the production methods of Examples 1-6 and Comparative Examples 1-3. The A layers of two films prepared by each production method were heat-sealed together, and then the heat-sealed joint was pulled apart using a tensile testing machine. It was found that the A layers of the films produced by the Examples were firmly heat-sealed together and separated from the B layer, while the three layers of the films produced by the Comparative Examples did not separate. This shows that by using different raw materials for the outer layer A, the middle layer B, and the outer layer C, this scheme can make the three-layer co-extruded film completely separable.

[0087] By heat-sealing the A layer of the products in Examples 1-6 and Comparative Examples 1-3 together, and then pulling the heat-sealed area apart with a tensile testing machine, it was found that the A layers were firmly heat-sealed together and separated from the B layer. However, the three layers of the film in Comparative Examples 1-3 could not be separated. This shows that by using different materials for the outer layer A, the middle layer B, and the outer layer C, this method can make the three-layer co-extruded film completely separable.

[0088] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thin film comprising, from the outside to the inside, an outer layer A, a middle layer B, and an outer layer C, characterized in that, The outer layer A comprises the following raw materials in parts by weight: 80-100 parts flexible polypropylene, 1-3 parts polyolefin elastomer, 3-6 parts UV-resistant anti-aging agent; The intermediate layer B comprises the following raw materials in parts by weight: 80-100 parts high-strength polyethylene, 1-5 parts polyolefin elastomer, 10-15 parts colorant; The outer layer C comprises the following raw materials in parts by weight: 80-100 parts flexible polypropylene, 1-5 parts polyolefin elastomer, 3-6 parts UV-resistant antioxidant; The raw material mass ratio of the outer layer A, the middle layer B, and the outer layer C is 3:8:3; The flexible polypropylene grades in outer layer A and outer layer C are each independently 208CF Borouge, and the polyolefin elastomer grades in outer layer A and outer layer C are each independently 6102FL Exxon. The high-strength polyethylene in the intermediate layer B is of grade ST50 Dow, and the polyolefin elastomer in the intermediate layer B is of grade 7266 Dow. The UV-resistant anti-aging agent is one or more of p-nitroaniline, N-phenyl-α-naphthylamine, and N-phenyl-N-cyclohexyl-p-phenylenediamine.

2. The thin film according to claim 1, characterized in that, The colorant is one or both of black masterbatch and titanium dioxide.

3. A thin film manufacturing process according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Mix the raw materials in outer layer A, melt and extrude to obtain outer layer A extrusion material; S2. Mix the raw materials in the intermediate layer B, melt and extrude to obtain the intermediate layer B extrusion material; S3. Mix the raw materials in the outer layer C, melt and extrude to obtain the outer layer C extrusion material; S4. The outer layer A extrusion material, the middle layer B extrusion material, and the outer layer C extrusion material are filtered through a filter screen, connected, and distributed into three layers A, B, and C by a distributor. The mixture is then formed through a die head, cooled, and dried to obtain a film.

4. The thin film production process according to claim 3, characterized in that, In steps S2 and S3, a desiccant is added. In step S2, the amount of desiccant added accounts for 0.5% to 1% of the total mass of the intermediate layer B raw material, and in step S3, the amount of desiccant added accounts for 0.5% to 1% of the total mass of the outer layer C raw material. The desiccant is alumina or silica gel.

5. The thin film production process according to claim 3, characterized in that, In step S1, when the outer layer A is melt-extruded, the barrel temperature is 165~235℃; in step S2, when the middle layer B is melt-extruded, the barrel temperature is 170~205℃; and in step S3, when the outer layer C is melt-extruded, the barrel temperature is 170~245℃.

6. The thin film production process according to claim 3, characterized in that, In step S1, during the melt extrusion of the outer layer A, the barrel temperature is divided into zones 1 to 6, with temperatures as follows: Zone 1: 165℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 235℃, Zone 6: 235℃. In step S2, during the melt extrusion of the middle layer B, the barrel temperature is divided into zones 1 to 7, with temperatures as follows: Zone 1: 175℃, Zone 2: 185℃, Zone 3: 195℃, Zone 4: 205℃, Zone 5: 205℃, Zone 6: 205℃. Zones 5, 6: 205℃, and 7: 205℃; During the melt extrusion of the outer layer C in step S3, the barrel temperature is divided into zones 1 to 7, with the temperatures as follows: Zone 1: 175℃, Zone 2: 205℃, Zone 3: 225℃, Zone 4: 235℃, Zone 5: 245℃, Zone 6: 245℃, and Zone 7: 245℃; In step S4, the die distributor temperature is divided into zones 1 to 13, and the temperature of each of zones 1 to 13 is 285℃.

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