A covering film and its preparation process

Abstract

The present application relates to the technical field of packaging materials, particularly to a lidding film and its preparation process. A lidding film comprises a surface layer and an inner layer, the surface layer and inner layer being bonded together with a solvent-free adhesive; the surface layer is a PET film layer; the inner layer is prepared from the following components in parts by weight: 20-30 parts low-density polyethylene, 40-60 parts olefin copolymer, 10-20 parts metallocene polyethylene, 1-5 parts antibacterial agent, and 1-5 parts composite antimicrobial agent; wherein the olefin copolymer is an ethylene-1-octene copolymer and an ethylene-propylene block copolymer in a mass ratio of (1-1.3):(3-3.5). The present application has the effect of improving the heat-sealing and antimicrobial properties of the lidding film.

Description

Technical Field

[0001] The present application relates to the technical field of packaging materials, and in particular to a covering film and a preparation process thereof. Background Art

[0002] Lidding film is a composite packaging material widely used for sealing various containers. For example, it is used for lidding barrels and boxes made of PE and PP materials. Currently, the commonly used inner layer materials of lidding films are PP and PE films. PP film has good heat-sealing strength, but its heat-sealing temperature is relatively high, resulting in high electrical and heat losses in the sealing equipment. PE film has a lower heat-sealing temperature, and while it can meet the requirements of most packaging materials, its stiffness, tensile strength, and heat-sealing strength are inferior to PP film, and its heat-sealing effect on PP containers is not as good.

[0003] Related technologies propose combining PE film with PP film, which boasts high transparency, high melting point, high barrier properties, and high stiffness. This allows for sealing at low temperatures, with high sealing speeds and improved heat-sealing film strength. To improve the compatibility of PE and PP, the proposed solution also incorporates POE as a coupling layer to bond with the PP film. However, this can lead to delamination of the heat-sealing film during the heat-sealing process, reducing heat-sealing strength and resulting in suboptimal heat-sealing performance for the overall lidding film. Summary of the Invention

[0004] In order to solve the above technical problems, the present application provides a covering film and a preparation process thereof.

[0005] In a first aspect, the present application provides a covering film, which is realized by the following technical solutions:

[0006] A lidding film, comprising a surface layer and an inner layer, wherein the surface layer and the inner layer are bonded together by a solvent-free adhesive; the surface layer is a PET film layer; and the inner layer is prepared from the following components in parts by weight:

[0007] 20-30 parts low-density polyethylene

[0008] 40-60 parts of olefin copolymer

[0009] 10-20 parts of metallocene polyethylene

[0010] 1-5 parts of opening agent

[0011] 1-5 parts of compound antibacterial agent;

[0012] The olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of (1-1.3): (3-3.5).

[0013] By adopting the above technical solution, the inner layer of the lidding film produced by this application utilizes a blend of low-density polyethylene and metallocene polyethylene to enhance low-temperature heat-sealing performance. The addition of polypropylene via ethylene-propylene block copolymer enhances the heat-sealing strength of the film layer and improves the processing performance of the metallocene polyethylene. The ethylene-1-octene copolymer effectively improves the compatibility between the various materials, resulting in excellent miscibility between the various materials in the film layer and superior heat-sealing performance of the inner film. The addition of a composite antimicrobial agent enhances the antimicrobial properties of the inner film during sealing.

[0014] Preferably, the weight ratio of the ethylene-1-octene copolymer to the ethylene-propylene block copolymer in the olefin copolymer is 1.25:(3-3.2).

[0015] By adopting the above technical solution, within this ratio range, the two olefin copolymers can better play their respective roles, thereby improving the heat sealing performance of the film layer.

[0016] Preferably, the ethylene-1-octene copolymer is prepared by mixing ethylene-1-octene random copolymer and ethylene-1-octene block copolymer in a mass ratio of 1:(0.2-0.3); and the ethylene content in the ethylene-propylene block copolymer is 10-15%.

[0017] By adopting the above technical solution, the ethylene-1-octene random copolymer has a narrow molecular weight distribution and comonomer distribution, a uniform distribution of short chain branches, and exhibits high elasticity, high strength, high elongation, and good low-temperature performance. The ethylene-1-octene block copolymer has superior performance compared to the ethylene-1-octene random copolymer and has excellent compatibility with resins. Mixing the two copolymer forms can significantly improve the heat-sealing performance of the inner layer. By limiting the ethylene content in the ethylene-propylene block copolymer, the polypropylene component of the inner layer film material can be better matched with other polyethylene materials, further enhancing the heat-sealing performance of the film.

[0018] Preferably, the weight ratio of the low-density polyethylene to the olefin copolymer and the metallocene polyethylene is (1.2-1.4): (2.3-2.5): (0.6-0.8).

[0019] By adopting the above technical solution, within the above-mentioned weight ratio range, the metallocene polyethylene can effectively exert its low-temperature heat-sealing performance. The ethylene-propylene block copolymer in the olefin copolymer can not only significantly improve the processing performance of low-density polyethylene and metallocene polyethylene, but also increase the propylene content in the PE film layer, enhance the heat-sealing strength of the inner film, and can excellently heat-seal containers made of PP and PE. The ethylene-1-octene copolymer can effectively improve the compatibility between the various materials and has excellent low-temperature performance, thereby improving the low-temperature heat-sealing performance of the modified inner layer.

[0020] Preferably, the composite antibacterial agent is a combination of P210Z composite antibacterial agent and P210T composite antibacterial agent in a weight ratio of (0.2-0.5): (0.5-0.8).

[0021] By adopting the above technical solution, the P210Z composite antibacterial agent uses composite zirconium phosphate to load two antibacterial active ingredients, silver ions and zinc ions, and the P210T composite antibacterial agent uses composite zirconium phosphate to load two antibacterial active ingredients, silver ions and titanium oxide. The two composite antibacterial agents are mixed in an appropriate weight ratio, which has a synergistic effect and has good inhibitory and bactericidal effects on Escherichia coli, Staphylococcus aureus, Candida albicans, etc.

[0022] Preferably, the opening agent is a silicon dioxide anti-adhesive agent, the silicon dioxide content in the silicon dioxide anti-adhesive agent is 98-99.8%, and the average particle size is 4-10 μm.

[0023] By adopting the above technical solution, the silica in the silica anti-blocking agent exists in a spherical form, has good fluidity, high slipperiness, low haze, and high transparency. By limiting the particle size distribution range of silica, it has good compatibility with the resin and good dispersibility.

[0024] In a second aspect, the present application provides a process for preparing a capping film, which is achieved through the following technical solution: A process for preparing a capping film, comprising the following steps:

[0025] S1. Inner layer preparation

[0026] a) Melt-blend accurately measured amounts of low-density polyethylene, metallocene polyethylene, and olefin copolymer in a high-speed mixer for 30-45 minutes to obtain blend A;

[0027] b: Melt and blend the accurately measured antibacterial agent, composite antibacterial agent and blend A in a high-speed mixer for 10-15 minutes to obtain blend B, and then extrude blend B to obtain a blend masterbatch, which is then extruded and cast into a film to obtain the inner layer;

[0028] S2. The inner layer obtained in S1 is subjected to single-sided corona treatment, and the corona-treated side of the inner layer is laminated with the surface layer through a solvent-free adhesive, and then subjected to a 24-48h aging treatment to finally obtain a lidding film product.

[0029] By adopting the above technical solution, metallocene polyethylene, low-density polyethylene and olefin copolymer are first blended and modified. Metallocene polyethylene has the effect of improving heat sealing performance. The ethylene-propylene block copolymer not only increases the polypropylene content in the PE film layer, further improving the heat sealing performance, but also effectively improves the processing difficulty of metallocene polyethylene when used as a modified material. Ethylene-1-octene copolymer has a good effect of improving resin compatibility and toughening the material. Then, by adding an anti-blocking agent and a composite antibacterial agent, the anti-adhesion and antibacterial properties of the inner layer film are improved.

[0030] Single-sided corona treatment of the inner layer prepared by S1 has a good effect on improving the bonding strength between the inner layer and the surface layer, and has little effect on the heat sealing performance of the inner layer, thereby preparing a sealing film with excellent heat sealing performance.

[0031] Preferably, in said S1, the specific operation of extruding the blended masterbatch in step b is as follows: the screw speed is 450-500r / min, and it is melted into a fluid at 190-220°C, the first temperature zone is 190-195°C, the second temperature zone is 200-205°C, the third temperature zone is 210-215°C, the fourth temperature zone is 215-220°C, and the die temperature is 210-220°C; and then the blended masterbatch is extruded and cast into a film, the temperature of the feeding section and the homogenizing section is controlled between 195-230°C, the die temperature is controlled at 210-230°C, and the surface temperature of the cooling roller is controlled at 20-50°C.

[0032] By adopting the above technical solution and performing the above operations, under the conditions of limiting the screw speed and the temperature in each stage, the processing effect of the blend B is better, thereby obtaining an inner layer film with excellent heat sealing performance.

[0033] In summary, this application has the following advantages:

[0034] 1. This application utilizes a blend of low-density polyethylene and metallocene polyethylene to enhance the low-temperature heat-sealing performance of the inner layer. The addition of polypropylene via ethylene-propylene block copolymer improves the heat-sealing strength of the film. Ethylene-1-octene copolymer effectively improves the compatibility between the various materials, resulting in an inner film with excellent heat-sealing properties. A composite antimicrobial agent enhances the antimicrobial properties of the inner film during sealing. Finally, the inner layer is composited with a PET film layer to produce a lidding film with excellent performance.

[0035] 2. The preparation method of the present application is relatively simple, has low operational difficulty, and is easy to implement industrial production and manufacturing. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to comparative examples and embodiments.

[0037] Example

[0038] Example 1

[0039] The present application discloses a lidding film comprising a surface layer and an inner layer, wherein the surface layer and the inner layer are bonded together by a solvent-free adhesive. The solvent-free adhesive is a two-component solvent-free polyester adhesive 9106.

[0040] The outer layer of the lidding film is a commercially available PET film. The inner layer is primarily made from the following ingredients, calculated by weight: 24 parts low-density polyethylene, 48 parts olefin copolymer, 15 parts metallocene polyethylene, 2 parts SN-Q55 silica anti-blocking agent, and 4 parts composite antimicrobial agent.

[0041] The olefin copolymer is composed of an ethylene-1-octene copolymer and an ethylene-propylene block copolymer in a mass ratio of 1:3. The ethylene-1-octene copolymer is a mixture of an ethylene-1-octene random copolymer (POE Vistamaxx VM3980) and an ethylene-1-octene block copolymer (OBC Dow INFUSE 9107) in a mass ratio of 1:0.2. The ethylene content of the ethylene-propylene block copolymer is 12%.

[0042] Low-density polyethylene uses 1905UMS raw material, CAS number is 9002-88-4, melt mass flow rate MFR, 2.16kg is 5g / 10min, density is 0.919g / cm 3 Metallocene polyethylene uses 2012MAMVLDPE plastic raw material.

[0043] The SN-Q55 silica anti-adhesive agent contains more than 99.6% silica and has an average particle size of 4-7 μm. The composite antibacterial agent is a mixture of P210Z composite antibacterial agent and P210T composite antibacterial agent in a weight ratio of 0.2:0.8.

[0044] A process for preparing a covering film comprises the following steps:

[0045] S1. Inner layer preparation

[0046] a) Melt-blending accurately measured amounts of low-density polyethylene, metallocene polyethylene, and olefin copolymer in a high-speed mixer for 30 minutes to obtain blend A;

[0047] b: Melt and blend the accurately measured antibacterial agent, composite antibacterial agent and blend A in a high-speed mixer for 15 minutes to obtain blend B, and then extrude blend B at a screw speed of 450r / min, melt into a fluid at 190-220°C, the first temperature zone is 190°C, the second temperature zone is 200°C, the third temperature zone is 210°C, the fourth temperature zone is 215°C, and the die head temperature is 220°C to obtain a blended masterbatch;

[0048] The blended masterbatch is then extruded and cast into a film. The temperature of the feeding section and the homogenizing section is controlled between 195-230°C. The extrusion temperature is divided into 8 zones, namely: 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, and 230°C. The die head temperature is controlled at 230°C, and the surface temperature of the cooling roller is controlled at 40°C. The blended masterbatch is extruded and cast into a film to obtain the inner layer.

[0049] S2: The inner layer obtained in S1 is subjected to single-sided corona treatment, and the corona-treated side of the inner layer is laminated with the surface layer using a solvent-free adhesive, and then aged at 25°C for 48 hours to obtain a lidding film product. The surface layer has a gram weight of 28g / m 3 , the inner layer is 35g / m 3 , the glue amount is 15g / m 3 .

[0050] Example 2

[0051] The difference between Example 2 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1:3.5.

[0052] Example 3

[0053] The difference between Example 3 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1.3:3.

[0054] Example 4

[0055] The difference between Example 4 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1.3:3.5.

[0056] Example 5

[0057] The difference between Example 5 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1.25:3.

[0058] Example 6

[0059] The difference between Example 6 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1.25:3.5.

[0060] Example 7

[0061] The difference between Example 7 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1.25:3.2.

[0062] Example 8

[0063] The difference between Example 8 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1.25:3.1.

[0064] Example 9

[0065] The difference between Example 9 and Example 8 is that the raw materials for preparing the inner layer include 24 parts of low-density polyethylene, 46 parts of olefin copolymer, and 12 parts of metallocene polyethylene.

[0066] Example 10

[0067] The difference between Example 10 and Example 8 is that the raw materials for preparing the inner layer include 28 parts of low-density polyethylene, 50 parts of olefin copolymer, and 16 parts of metallocene polyethylene.

[0068] Example 11

[0069] The difference between Example 11 and Example 8 is that the raw materials for preparing the inner layer include 24 parts of low-density polyethylene, 48 parts of olefin copolymer, and 12 parts of metallocene polyethylene.

[0070] Example 12

[0071] The difference between Example 12 and Example 8 is that the raw materials for preparing the inner layer include 26 parts of low-density polyethylene, 40 parts of olefin copolymer, and 14 parts of metallocene polyethylene.

[0072] Example 13

[0073] The difference between Example 13 and Example 8 is that the raw materials for preparing the inner layer include 20 parts of low-density polyethylene, 48 parts of olefin copolymer, and 20 parts of metallocene polyethylene.

[0074] Example 14

[0075] The difference between Example 14 and Example 8 is that the raw materials for preparing the inner layer include 20 parts of low-density polyethylene, 40 parts of olefin copolymer, and 20 parts of metallocene polyethylene.

[0076] Example 15

[0077] The difference between Example 15 and Example 1 is that in the raw materials for preparing the inner layer, the composite antibacterial agent is a combination of P210Z composite antibacterial agent and P210T composite antibacterial agent in a weight ratio of 0.5:0.5.

[0078] Example 16

[0079] The difference between Example 16 and Example 1 is that in the raw materials for preparing the inner layer, the composite antibacterial agent is a combination of P210Z composite antibacterial agent and P210T composite antibacterial agent in a weight ratio of 0.4:0.6.

[0080] Comparative Example

[0081] The difference between Comparative Example 1 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 1:2.

[0082] The difference between Comparative Example 2 and Example 1 is that in the raw materials for preparing the inner layer, the olefin copolymer is composed of ethylene-1-octene copolymer and ethylene-propylene block copolymer in a mass ratio of 2:2.

[0083] The difference between Comparative Example 3 and Example 1 is that in the raw materials for preparing the inner layer, the composite antibacterial agent is a combination of P210Z composite antibacterial agent and P210T composite antibacterial agent in a weight ratio of 0.1:0.9.

[0084] The difference between Comparative Example 4 and Example 1 is that in the raw materials for preparing the inner layer, the composite antibacterial agent is a combination of P210Z composite antibacterial agent and P210T composite antibacterial agent in a weight ratio of 0.6:0.4.

[0085] Performance testing

[0086] Detection method

[0087] Experiment 1: Heat Seal Strength Test: The heat sealability of the inner layer material of the lidding films of Examples 1-14 and Comparative Examples 1-2 to CPP was tested. Heat sealing was performed at gradually increasing heat sealing temperatures (increasing the heat sealing temperature by approximately 3°C). The heat seal strength at different temperatures was measured using a tensile testing machine. Testing and characterization were performed in accordance with the QB / T2358-1998 standard using a GBB-A1 electronic heat seal tester with a single-blade heating blade and a heating width of 5 mm or greater.

[0088] Experiment 2: Puncture Strength Test: The puncture strength of the lidding films of Examples 1-14 and Comparative Examples 1-2 was measured according to GB / T 21302-2007 using an LC-202G film puncture strength tester.

[0089] Experiment 3: Antibacterial Performance Testing: The antibacterial properties of the lidding films prepared in Examples 1, 15, and 16 and Comparative Examples 3 and 4 were tested in accordance with QB / T 2591-2003, "Antibacterial Plastics - Antibacterial Performance Test Method and Antibacterial Effect." The antibacterial test target was the inner layer of the lidding film. The antibacterial rate was calculated using the formula: R (%) = (BC) / B x 100; where: R = antibacterial rate (%); B = average recovered bacterial count (cfu / sheet) of the blank control sample; and C = average recovered bacterial count (cfu / sheet) of the antibacterial plastic sample.

[0090] Test results

[0091] The performance test results of Examples 1-16 and Comparative Examples 1-4 are shown in Table 1-2.

[0092] Table 1 Test data of puncture resistance and heat sealing performance of Examples 1-14 and Comparative Examples 1-2

[0093]

[0094]

[0095] From Examples 1-8 and Comparative Examples 1 and 2, and from Table 1, it can be seen that in the material of the inner layer of the lidding film, the mass ratio of the ethylene-1-octene copolymer to the ethylene-propylene block copolymer in the olefin copolymer within the range of 1.25:(3-3.2) can achieve excellent heat-sealing performance at various gradient temperatures. Furthermore, when the mass ratio of the ethylene-1-octene copolymer to the ethylene-propylene block copolymer is 1.25:3.1, the heat-sealing performance of the inner layer of the lidding film is optimal. When the mass ratio exceeds the range of (1-1.3):(3-3.5) defined in this application, the two components in the olefin copolymer cannot effectively improve the compatibility and processability of the components in the film layer, and the heat-sealing performance of the film layer is affected.

[0096] Based on the premise that the mass ratio of ethylene-1-octene copolymer and ethylene-propylene block copolymer in olefin copolymer is 1.25:3.1, comparing Example 8 with Examples 9-11, by adjusting the weight ratio of low-density polyethylene, olefin copolymer and metallocene polyethylene, and considering the heat sealing performance and puncture strength of the comprehensive film layer, the weight ratio of low-density polyethylene, olefin copolymer and metallocene polyethylene is 1.2:2.4:0.6, which is most suitable, and can make the sealing film have good low-temperature heat sealing performance and good puncture resistance. Comparing Example 8 with Examples 12-14, when the weight ratio of the three exceeds the range defined in this application, the heat sealing performance and puncture strength of the film layer will be reduced. Since the addition amount of olefin copolymer and metallocene polyethylene is not within the appropriate range, the processing performance of metallocene polyethylene is not well improved, and the miscibility effect is also poor, which affects the heat sealing performance of the film layer.

[0097] Table 2 Antibacterial performance test data of Examples 1, 12, 13 and Comparative Examples 6, 7

[0098]

[0099] From Examples 1, 15, 16 and Comparative Examples 3 and 4 and Table 2, it can be seen that the P210Z composite antibacterial agent and the P210T composite antibacterial agent in the composite antibacterial agent have excellent antibacterial effects within the weight ratio range of (0.2-0.5): (0.5-0.8). When the weight ratio of the two exceeds the range, the antibacterial effect will be weakened. On the whole, when the weight ratio of the P210Z composite antibacterial agent and the P210T composite antibacterial agent is 0.4:0.6, the antibacterial effect reaches the best.

[0100] In summary, the puncture strength and low-temperature heat sealing performance of the sealing film of the present application are significantly improved, and the antibacterial property of the product is also significantly improved. The synergistic combination of ethylene-1-octene copolymer and ethylene-propylene block copolymer in olefin copolymers solves the problem of difficult processing during modification of metallocene polyethylene, and also improves the low-temperature heat sealing property of the sealing film. The antibacterial effect is enhanced by adding a composite antibacterial agent, further enhancing its application performance.

[0101] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A covering film, characterized in that: The lidding film is composed of a surface layer and an inner layer, and the surface layer and the inner layer are bonded by a solvent-free adhesive; the surface layer is a PET film layer; and the inner layer is prepared from the following components in parts by weight: 20-30 parts low-density polyethylene 40-60 parts of olefin copolymer 10-20 parts of metallocene polyethylene 1-5 parts of opening agent 1-5 parts of compound antibacterial agent; The olefin copolymer is composed of an ethylene-1-octene copolymer and an ethylene-propylene block copolymer in a mass ratio of (1-1.3): (3-3.5); the ethylene-1-octene copolymer is formed by mixing an ethylene-1-octene random copolymer and an ethylene-1-octene block copolymer in a mass ratio of 1: (0.2-0.3); and the ethylene content in the ethylene-propylene block copolymer is 10-15%.

2. The covering film according to claim 1, wherein: The weight ratio of the ethylene-1-octene copolymer to the ethylene-propylene block copolymer in the olefin copolymer is 1.25:(3-3.2).

3. The covering film according to claim 1, wherein: The weight ratio of the low-density polyethylene to the olefin copolymer and the metallocene polyethylene is (1.2-1.4): (2.3-2.5): (0.6-0.8).

4. The covering film according to claim 1, wherein: The composite antibacterial agent is prepared by mixing the P210Z composite antibacterial agent and the P210T composite antibacterial agent in a weight ratio of (0.2-0.5): (0.5-0.8).

5. The covering film according to claim 1, wherein: The opening agent is a silicon dioxide anti-adhesive agent, the silicon dioxide content in the silicon dioxide anti-adhesive agent is 98-99.8%, and the average particle size is 4-10 μm.

6. A process for preparing a lidding film according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Inner layer preparation a) Melt-blend accurately measured amounts of low-density polyethylene, metallocene polyethylene, and olefin copolymer in a high-speed mixer for 30-45 minutes to obtain blend A; b: Melt and blend the accurately measured antibacterial agent, composite antibacterial agent and blend A in a high-speed mixer for 10-15 minutes to obtain blend B, and then extrude blend B to obtain a blend masterbatch, which is then extruded and cast into a film to obtain the inner layer; S2. The inner layer obtained in S1 is subjected to single-sided corona treatment, and the corona-treated side of the inner layer is laminated with the surface layer through a solvent-free adhesive, and then subjected to a 24-48h aging treatment to finally obtain a lidding film product.

7. The process for preparing a lidding film according to claim 6, wherein: In the S1, the specific operation of extruding the blended masterbatch in step b is as follows: the screw speed is 450-500 r / min, the masterbatch is melted into a fluid at 190-220°C, the first temperature zone is 190-195°C, the second temperature zone is 200-205°C, the third temperature zone is 210-215°C, the fourth temperature zone is 215-220°C, and the die temperature is 210-220°C; then the masterbatch is extruded and cast into a film, the temperatures of the feeding section and the homogenizing section are controlled between 195-230°C, the die temperature is controlled at 210-230°C, and the surface temperature of the cooling roller is controlled at 20-50°C.

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