Low-temperature heat-sealable antistatic PE film and its preparation method, packaging bags

Abstract

This application provides a low-temperature heat-sealable antistatic PE film, comprising a three-layer co-extruded layer formed by three-layer co-extrusion blown film. The three-layer co-extruded layer includes an inner layer, a middle layer, and an outer layer. The inner layer includes MVLDPE, MLLDPE, EVA, LDPE, an opening slip agent, and PPA. The middle layer includes LLDPE, LDPE, and PPA. The outer layer includes LLDPE, LDPE, PPA, and an antistatic agent. This application also provides a method for preparing the PE film and packaging bags made from the PE film. The PE film of this application has good low-temperature heat-sealing properties, heat adhesion, antistatic properties, and anti-fouling properties.

Description

Technical Field

[0001] This invention relates to the technical field of packaging films, specifically to a low-temperature heat-sealing antistatic PE film, its preparation method, and packaging bags. Background Technology

[0002] Compared to traditional packaging, jelly used to be mainly packaged in cups. The disadvantages were that the small cup packaging could easily cause choking in children and the packaging bags were too difficult to tear. In recent years, jelly packaging has taken over the market with the form of large bags repackaged into small bags. And the form of small bag repackaging is automated roll film filling.

[0003] During the jelly film packaging process, due to the high packaging speed, generally exceeding 200 packs / min, the PE used as the heat-sealing layer must be capable of low-temperature heat sealing. In addition, since the jelly film is a gel-like substance, liquid contamination occurs on the heat-sealing line, requiring the PE to have good anti-contamination and good thermal adhesion. Finally, after filling, die-cutting and stamping are usually performed. The waste shavings generated during stamping are prone to electrostatic adsorption, which can adhere to the jelly bag, resulting in serious foreign matter contamination. Therefore, the PE must have good antistatic properties. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a PE film with better low-temperature heat-sealing properties, thermal adhesion, antistatic properties and anti-fouling properties.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A low-temperature heat-sealable antistatic PE film comprises a three-layer co-extruded layer formed by three-layer co-extrusion blown film. The three-layer co-extruded layer includes an inner layer, a middle layer, and an outer layer. The inner layer includes MVLDPE, MLLDPE, EVA, LDPE, an opening slip agent, and PPA. The middle layer includes LLDPE, LDPE, and PPA. The outer layer includes LLDPE, LDPE, PPA, and an antistatic agent.

[0007] In some possible implementations, the components of the inner layer are as follows by weight percentage:

[0008]

[0009] The components of the middle layer are as follows by weight percentage:

[0010] LLDPE 75%-79%;

[0011] LDPE 20%-24%;

[0012] PPA 0.3%–1%;

[0013] The components of the outer layer are as follows by weight percentage:

[0014]

[0015] In some possible implementations, the MVLDPE is of type SP0540, the MLLDPE is of type 1018MF, the EVA is of type 3172Z, the LDPE is of type 2426K, the PPA is of type A1058, the LLDPE in the middle layer is of type 0220KJ, and the LLDPE in the outer layer is of type 1002AY.

[0016] In some possible implementations, the type of the opening slip agent is SF-002, and the type of the antistatic agent is SX-102.

[0017] In some possible implementations, the thickness ratio of the inner layer, the middle layer, and the outer layer is 1:1:1.

[0018] This application also provides a method for preparing a low-temperature heat-sealable antistatic PE film, wherein the preparation method uses the various layers of the low-temperature heat-sealable antistatic PE film, and the preparation method includes the following steps:

[0019] After the components of the inner layer are mixed evenly, they are fed into the inner layer hopper of the three-layer co-extrusion blown film machine;

[0020] After the components of the middle layer are mixed evenly, they are fed into the middle layer hopper of the three-layer co-extrusion blown film machine;

[0021] After the components of the outer layer are mixed evenly, they are fed into the outer hopper of the three-layer co-extrusion blown film machine.

[0022] The three-layer co-extrusion blown film machine melts and extrudes the components in each hopper through each extrusion screw to the die head to blow into the PE film.

[0023] In some possible implementations, the inner screw barrel temperature is 210-215°C, the middle screw barrel temperature is 195-200°C, the outer screw barrel temperature is 210-215°C, and the flow channel temperature of the die head is 210°C.

[0024] In some possible implementations, the blow-up ratio of the three-layer co-extrusion blown film machine is 3-3.5.

[0025] This application also provides a packaging bag made using the aforementioned low-temperature heat-sealing antistatic PE film.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] In this application, the inner layer uses metallocene polyethylene with a narrow molecular weight distribution and a single side chain distribution, combined with LDPE, EVA, and PPA to provide polar groups. This allows the polar group-providing components to influence the crystallization behavior of polyethylene, the curing process of the inner layer, and the surface interactions at the interface, thereby affecting the hot solubility, curing efficiency, and hot tack of the inner layer. Consequently, the inner layer exhibits both good low-temperature heat-sealing properties and good hot tack. Furthermore, the composition of the inner, middle, and outer layers facilitates the effective antistatic action of the antistatic agent, resulting in good antistatic properties for the PE film. Additionally, the composition of the inner, middle, and outer layers can alter the surface properties of the PE film, thus giving it good antifouling properties. Detailed Implementation

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

[0029] One embodiment of this application provides a low-temperature heat-sealable antistatic PE film, comprising a three-layer co-extruded layer formed by three-layer co-extrusion blown film. The three-layer co-extruded layer includes an inner layer, a middle layer, and an outer layer. The inner layer comprises metallocene very low-density polyethylene (MVLDPE), metallocene linear low-density polyethylene (MLLDPE), ethylene-vinyl acetate copolymer (EVA), low-density polyethylene (LDPE), an opening slip agent, and PPA. The middle layer comprises linear low-density polyethylene (LLDPE), LDPE, and PPA. The outer layer comprises LLDPE, LDPE, PPA, and an antistatic agent. In this embodiment, the addition of PPA has the following advantages: improved surface gloss and smoothness of the plastic film; elimination of sharkskin and watermarks caused by melt fracture; reduction of crystal points caused by equipment and raw material factors; reduction of extruder current and pressure under unchanged equipment and process conditions, thereby improving equipment production efficiency; reduction of die temperature; improved film bubble stability; improved plasticizing function of basic equipment; improved melt flowability; and improved overall product performance.

[0030] In some embodiments, the components of the inner layer are as follows by weight percentage:

[0031]

[0032]

[0033] The components of the middle layer are as follows by weight percentage:

[0034] LLDPE 75%-79%;

[0035] LDPE 20%-24%;

[0036] PPA 0.3%–1%;

[0037] The components of the outer layer are as follows by weight percentage:

[0038]

[0039] In this application, the inner layer uses metallocene polyethylene with a narrow molecular weight distribution and a single side chain distribution, combined with LDPE, EVA, and PPA to provide polar groups. This allows the polar group-providing components to influence the crystallization behavior of polyethylene, the curing process of the inner layer, and the surface interactions at the interface, thereby affecting the hot solubility, curing efficiency, and hot tack of the inner layer. Consequently, the inner layer exhibits both good low-temperature heat-sealing properties and good hot tack. Furthermore, the composition of the inner, middle, and outer layers facilitates the effective antistatic action of the antistatic agent, resulting in good antistatic properties for the PE film. Additionally, the composition of the inner, middle, and outer layers can alter the surface properties of the PE film, thus giving it good antifouling properties.

[0040] In some embodiments, the MVLDPE is of model SP0540, and the MVLDPE of model SP0540 is...

[0041] This film features good impact resistance and ultra-low temperature heat-sealing strength. The MLLDPE is designated 1018MF, which further enhances its thermal adhesion and puncture resistance. The EVA is designated 3172Z, which further enhances its thermal adhesion and low-temperature heat-sealing properties. The LDPE is designated 2426K, which stabilizes the film bubble, thus ensuring the overall quality of the PE film. The PPA is designated A1058. In the middle layer, the LLDPE is designated 0220KJ, which offers good processing performance and opening properties, also contributing to the overall quality of the PE film. In the outer layer, the LLDPE is designated 1002AY, which exhibits good tensile strength and toughness.

[0042] In some embodiments, the type of the opening slip agent is SF-002, and the type of the antistatic agent is SX-102.

[0043] In some embodiments, the thickness ratio of the inner layer, the middle layer, and the outer layer is 1:1:1. This thickness selection facilitates performance balance, allowing the film to achieve a relatively balanced performance across different aspects.

[0044] Another embodiment of this application provides a method for preparing a low-temperature heat-sealable antistatic PE film. The method uses the components of each layer of the low-temperature heat-sealable antistatic PE film described in the above embodiments, and includes the following steps:

[0045] After the components of the inner layer are mixed evenly, they are fed into the inner layer hopper of the three-layer co-extrusion blown film machine.

[0046] After the components of the middle layer are mixed evenly, they are fed into the middle layer hopper of the three-layer co-extrusion blown film machine.

[0047] After the components of the outer layer are mixed evenly, they are fed into the outer hopper of the three-layer co-extrusion blown film machine.

[0048] The feeding sequence of the above-mentioned hoppers can be changed or is not important.

[0049] The three-layer co-extrusion blown film machine melts and extrudes the components in each hopper through each extrusion screw to the die head to blow into the PE film.

[0050] In some embodiments, the inner screw barrel temperature is 210-215°C, the middle screw barrel temperature is 195-200°C, the outer screw barrel temperature is 210-215°C, and the die runner temperature is 210°C. The selection of these temperatures offers the following advantages: 1. Ensures good material plasticization: Suitable temperatures allow polyethylene to fully melt and plasticize, ensuring material flowability and uniformity, thereby achieving good extrusion quality. 2. Optimizes product performance: Different temperature settings help adjust the molecular structure and crystallinity of each layer of material, thereby improving the physical properties of the product, such as strength, toughness, and transparency. 3. Improves production efficiency: Appropriate temperatures can reduce the residence time of material in the barrel, reducing the risk of material decomposition and degradation, improving the continuity and stability of production, and thus increasing production efficiency. 4. Reduces energy consumption: Reasonable temperature control can avoid energy waste caused by overheating and reduce production costs. 5. Reduces extrusion defects: Proper temperature selection can reduce the occurrence of extrusion defects such as bubbles, melt fracture, and surface roughness, improving the appearance quality and dimensional accuracy of the product. 6. Enhance the bonding force between layers: Appropriate temperature helps the materials between different layers to fuse and bond better, improving the integrity and stability of the multi-layer structure.

[0051] In some embodiments, the blow-up ratio of the three-layer co-extrusion blown film machine is 3-3.5.

[0052] In some embodiments, the cooling temperature of the three-layer co-extrusion blown film machine is 15±5℃.

[0053] Another embodiment of this application provides a packaging bag, which is prepared using the low-temperature heat-sealing antistatic PE film obtained in the above embodiments. For example, the inner layer of the PE film can be bent to heat-seal the packaging bag in opposite directions.

[0054] Example 1:

[0055] This embodiment provides a low-temperature heat-sealable antistatic PE film, comprising a three-layer co-extruded layer formed by three-layer co-extrusion blown film, wherein the three-layer co-extruded layer includes an inner layer, a middle layer, and an outer layer. By weight percentage, the inner layer comprises 45% MVLDPE (model SP0540, manufactured by Priman Japan), 20% MLLDPE (model 1018MF, manufactured by ExxonMobil), 8% EVA (model 3172Z, manufactured by DuPont USA), 20% LDPE (model 2426K, manufactured by CNOOC Shell), 1.5% opening slip agent (model SF-002, manufactured by Hengyang Laike New Materials Co., Ltd.), and 0.5% PPA (model A1058, a processing aid, a mixture, commercial name code DS-A1058, a product of Beijing Yalen Zhilian Technology Co., Ltd.). By weight percentage, the middle layer comprises 79% LLDPE (model 0220KJ, manufactured by Shanghai SECCO), 20% LDPE (model 2426K, manufactured by Sinopec), and 0.5% PPA (model A1058). The outer layer comprises 74.5% LLDPE (model 1002AY, manufactured by ExxonMobil), 20% LDPE (model 2426K), 0.5% PPA (model A1058), and 5% antistatic agent (model SX-102, manufactured or purchased from Shenzhen Shanxiang Environmental Protection Technology Co., Ltd.). The thickness ratio of the inner, middle, and outer layers is 1:1:1 (the specific blown film thickness can be 42µm, with the inner, middle, and outer layers each being 14µm).

[0056] The method for preparing the PE film in this embodiment includes the following steps:

[0057] After the components of the inner layer are mixed evenly, they are fed into the inner layer hopper of the three-layer co-extrusion blown film machine.

[0058] After the components of the middle layer are mixed evenly, they are fed into the middle layer hopper of the three-layer co-extrusion blown film machine.

[0059] After the components of the outer layer are mixed evenly, they are fed into the outer hopper of the three-layer co-extrusion blown film machine.

[0060] The three-layer co-extrusion blown film mill melts and extrudes the components in each hopper through the extrusion screws, which are then blown into the PE film through the die. The inner screw barrel temperature is 210°C. The middle screw barrel temperature is 198°C. The outer screw barrel temperature is 210°C. The die runner temperature is 210°C. The blow-up ratio of the three-layer co-extrusion blown film mill is 3. The cooling temperature of the three-layer co-extrusion blown film mill is 20°C.

[0061] Example 2:

[0062] The PE film provided in this embodiment differs from the PE film provided in Example 1 in that, by weight percentage, the inner layer comprises 50% MVLDPE, 20% MLLDPE, 8% EVA, 20% LDPE, 1.5% opening slip agent, and 0.5% PPA. The middle layer comprises 75% LLDPE, 24% LDPE, and 1% PPA by weight percentage. The outer layer comprises 72% LLDPE, 24% LDPE, 0.5% PPA, and 3.5% antistatic agent by weight percentage.

[0063] The preparation method in this embodiment differs from that in Example 1 in that the inner screw barrel temperature is 215°C, the middle screw barrel temperature is 200°C, the outer screw barrel temperature is 215°C, and the cooling temperature of the three-layer co-extrusion blown film machine is 18°C.

[0064] This application tests the properties of the PE film using the following method:

[0065] 1. Initial sealing temperature: The test is conducted according to QBT2358 "Test method for heat seal strength of plastic film bags"; the test conditions are: pressure of 0.3 MPa, time of 1 second, and the test instrument is a heat sealer.

[0066] 2. Antistatic performance test: The test temperature is 22±5℃, the test humidity is below 45%, and the test instrument is an electrostatic tester.

[0067] 3. Heat seal strength test: The testing instrument is a hot tack tester, and the testing standard is QBT2358 "Test method for heat seal strength of plastic film bags"; ASTM F1921 standard test method for heat seal strength (hot tack) of flexible mesh sealing surfaces made of thermoplastic polymers and mixtures.

[0068] 4. Anti-fouling heat seal test: Test the heat seal strength after water contamination on the membrane surface.

[0069] The test results of the above embodiments of this application are shown in the table below.

[0070]

[0071] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A low-temperature heat-sealable antistatic PE film, comprising a three-layer co-extruded layer formed by three-layer co-extrusion blown film, wherein the three-layer co-extruded layer comprises an inner layer, a middle layer, and an outer layer, characterized in that, The inner layer comprises MVLDPE, MLLDPE, EVA, LDPE, opening slip agent and PPA, the middle layer comprises LLDPE, LDPE and PPA, and the outer layer comprises LLDPE, LDPE, PPA and antistatic agent. The components of the inner layer are as follows by weight percentage: MVLDPE 45%-50%; MLLDPE 20%-22%; EVA 5%-8%; LDPE 20%; Opening lubricant 1.0%-1.5%; PPA 0.3%-0.5%; The components of the middle layer are as follows by weight percentage: LLDPE 75%-79%; LDPE 20%-24%; PPA 0.3%-1%; The components of the outer layer are as follows by weight percentage: LLDPE 72%-75%; LDPE 20%-24%; PPA 0.3%-0.5%; Antistatic agent 3%-5%.

2. The low-temperature heat-sealable antistatic PE film as described in claim 1, characterized in that, The MVLDPE is model SP0540, the MLLDPE is model 1018MF, the EVA is model 3172Z, the LDPE is model 2426K, the PPA is model A1058, the LLDPE in the middle layer is model 0220KJ, and the LLDPE in the outer layer is model 1002AY.

3. The low-temperature heat-sealable antistatic PE film as described in claim 1, characterized in that, The type of the opening slip agent is SF-002.

4. The low-temperature heat-sealable antistatic PE film as described in claim 1, characterized in that, The thickness ratio of the inner layer, the middle layer, and the outer layer is 1:1:

1.

5. A method for preparing a low-temperature heat-sealable antistatic PE film, characterized in that, The preparation method uses the components of each layer of the low-temperature heat-sealable antistatic PE film as described in any one of claims 1 to 4, and the preparation method includes the following steps: After the components of the inner layer are mixed evenly, they are fed into the inner hopper of the three-layer co-extrusion blown film machine; After the components of the middle layer are mixed evenly, they are fed into the middle layer hopper of the three-layer co-extrusion blown film machine; After the components of the outer layer are mixed evenly, they are fed into the outer hopper of the three-layer co-extrusion blown film machine. The three-layer co-extrusion blown film machine melts and extrudes the components in each hopper through each extrusion screw to the die head to blow into the PE film.

6. The preparation method according to claim 5, characterized in that, The inner screw barrel temperature is 210-215℃, the middle screw barrel temperature is 195-200℃, the outer screw barrel temperature is 210-215℃, and the flow channel temperature of the die head is 210℃.

7. The preparation method according to claim 5, characterized in that, The blow-out ratio of the three-layer co-extrusion blown film machine is 3-3.

5.

8. A packaging bag, characterized in that, It is prepared using the low-temperature heat-sealing antistatic PE film as described in any one of claims 1 to 4.

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