A blown wear-resistant packaging film for a liquid bag and a method for preparing the same and a liquid bag

Abstract

The application discloses a kind of packing film for packing liquid bag and its preparation method and packing liquid bag, belong to the technical field of preparation of packing film, it includes the film body sequentially from outside to inside by outer layer, middle layer and inner layer, characterized by: outer layer is made of 8-10 mass parts blow molding grade TPU and 0.5-1.5 mass parts slip agent, middle layer is made of 8.5-10.5 mass parts first metallocene linear low density polyethylene and 0.3-0.7 mass parts PPA, inner layer is made of 5-7 mass parts second metallocene linear low density polyethylene, 1-2 mass parts first low density polyethylene, 0.3-0.7 mass parts PPA, 0.5-1.5 mass parts opening agent and 0.5-1.5 mass parts slip agent, first metallocene linear low density polyethylene brand is XP8784ML, second metallocene linear low density polyethylene has lateral first long branch, and first low density polyethylene has lateral second long branch.This film can be blown into film and greatly improve its wear resistance under the premise of meeting the high mechanical property requirement of liquid bag.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of packaging film preparation, and particularly relates to a blown wear-resistant packaging film for liquid container bags and a preparation method thereof and a liquid container bag. BACKGROUND

[0002] With the development of logistics transportation, liquid is gradually transported by vehicles instead of pipelines, which has a high construction cost and is limited in route. Due to the particularity of liquid, the requirements for transportation equipment and conditions are relatively high. At present, liquid is mainly transported by tank trucks and liquid container bags in containers. The tank truck transportation is completed by using customized iron or aluminum tank trucks, which has a high transportation cost and cannot control the temperature during transportation, which is easy to cause liquid to spoil. The liquid container bag transportation is to fill the liquid to be transported in the liquid bag in the container. The liquid bag can avoid liquid leakage, pollution and other safety problems, effectively avoid cross contamination of goods, has the advantages of lower cost, no cleaning and the like compared with the tank truck, and is convenient for changing the transportation tool in the middle, thereby improving the versatility and interchangeability in sea, land and air transportation. Therefore, the liquid container bag is widely used in the field of non-dangerous liquid goods storage and transportation such as oil, syrup and red wine.

[0003] During transportation, it is found that the liquid bag is easy to be worn and torn, which causes liquid leakage, increases the loss of the transported liquid, pollutes the container or other goods, and increases the additional cleaning cost. The patent with the publication number CN119036987A discloses a bidirectional PE stretch film and a preparation method and application thereof. The film is composed of an outer layer, a middle layer and an inner layer. The outer layer is a TPU film, which includes TPU particles, ultraviolet absorbers and antioxidants. The middle layer is a matte PE film, which includes low-density polyethylene, linear low-density polyethylene, metallocene polyethylene, composite additives, polyphthalic amide, dispersants and antioxidants. The inner layer is a milky white PE film, which includes low-density polyethylene, high-density polyethylene and titanium white. Although the stretch film improves the processing performance, wear resistance and puncture resistance of the PE film while maintaining the good mechanical properties of the PE film through the synergistic effect of modified talc and polytetrafluoroethylene micro powder, the film can only be prepared by a stretching process. The mechanical properties such as strength of the stretch film cannot meet the requirements of the liquid bag, and the adjacent layers need to be glued, which complicates the preparation process and greatly reduces the production efficiency. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a blown wear-resistant packaging film for liquid container bags and a preparation method thereof and a liquid container bag, which can be blown into a film and greatly improve the wear resistance under the premise of meeting the high mechanical property requirements of the liquid bag.

[0005] To solve the above technical problems, the technical solution of the present application is to design a blown wear-resistant packaging film for liquid container bags, which comprises a film body composed of an outer layer, a middle layer and an inner layer from outside to inside.

[0006] The outer layer is made of the following raw materials by mass fraction:

[0007] Blow molding grade TPU 8-10 parts

[0008] Slip agent 0.5-1.5 parts

[0009] The intermediate layer is made of the following raw materials by mass fraction:

[0010] First metallocene linear low density polyethylene 8.5-10.5 parts

[0011] PPA 0.3-0.7 parts

[0012] The inner layer is made of the following raw materials by mass fraction:

[0013] Second metallocene linear low density polyethylene 5-7 parts

[0014] First low density polyethylene 1-2 parts

[0015] PPA 0.3-0.7 parts

[0016] Opening agent 0.5-1.5 parts

[0017] Slip agent 0.5-1.5 parts

[0018] The melt temperature of the blow molding grade TPU is 170-240℃, the first metallocene linear low density polyethylene is XP8784ML, and the second metallocene linear low density polyethylene has a first long side chain, and the first low density polyethylene has a second long side chain.

[0019] Preferably, the carrier of the opening agent is a second low density polyethylene, and the effective component is an artificially synthesized spherical silica, and the carrier of the slip agent is a linear low density polyethylene with a melt index of 2, and the effective component is a mustard amide.

[0020] Preferably, the first long side chain and the second long side chain are both side chains with more than 3 carbons.

[0021] Preferably, the thickness of the film body is 110-120μm.

[0022] Preferably, the thickness ratio of the outer layer, the intermediate layer and the inner layer is 1:2:1.

[0023] The application also provides a preparation method of the blow wear-resistant packaging film for the liquid bag, characterized by comprising the following steps:

[0024] (1) preparing the first special material: mixing 8-10 parts of blowing grade TPU with 0.5-1.5 parts of slip agent to obtain the first mixture; the melting temperature of the blowing grade TPU is 170-240℃;

[0025] (2) preparing the second special material: mixing 8.5-10.5 parts of the first metallocene linear low density polyethylene with 0.3-0.7 parts of PPA to obtain the second mixture; the first metallocene linear low density polyethylene is XP8784ML;

[0026] (3) preparing the third special material: mixing 5-7 parts of the second metallocene linear low density polyethylene, 1-2 parts of the first low density polyethylene, 0.3-0.7 parts of PPA, 0.5-1.5 parts of opening agent and 0.5-1.5 parts of slip agent to obtain the third mixture; the second metallocene linear low density polyethylene has lateral first long chain branches and the first low density polyethylene has lateral second long chain branches;

[0027] (4) film preparation: co-extrusion of the first mixture prepared in step (1), the second mixture prepared in step (2) and the third mixture prepared in step (3) to form the packaging film with the outer layer, the middle layer and the inner layer arranged from outside to inside.

[0028] Preferably, the carrier of the opening agent is the second low density polyethylene and the effective component is artificial synthetic spherical silica; the carrier of the slip agent is linear low density polyethylene with a melt index of 2 and the effective component is erucic acid amide.

[0029] Preferably, the first mixture of step (1), the second mixture of step (2) and the third mixture of step (3) are all granulated before entering step (4).

[0030] Preferably, in step (4), the extrusion temperature of the outer layer is 185-195℃, the extrusion temperature of the middle layer is 180-185℃ and the extrusion temperature of the inner layer is 180-190℃.

[0031] Preferably, the particle size of the spherical silica is 5-8μm.

[0032] Preferably, the grade of the first low density polyethylene is the same as that of the second low density polyethylene.

[0033] Preferably, the grade of the blowing grade TPU is 1195A.

[0034] Preferably, the grade of the second metallocene linear low density polyethylene is 2005.

[0035] Preferably, the grade of the first low density polyethylene is 105BR.

[0036] The present application also provides a liquid container bag, comprising a bag body which is heat sealed by a polyethylene film, characterized in that the polyethylene film is a packaging film prepared by the packaging film for the liquid container bag by blow molding or the method for preparing the packaging film for the liquid container bag by blow molding.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1. The present application enhances the wear resistance and rubbing resistance of the packaging film, increases the plasticity in the film preparation process, enhances the compatibility between the layers, improves the overall performance of the film, meets the higher mechanical performance requirements of the liquid bag on the packaging film, thereby preparing the wear-resistant packaging film for the liquid container bag by blow molding, and improving the heat sealing strength of the packaging film, which is beneficial to preparing the liquid container bag with high overall strength.

[0039] 2. The present application can enhance the mixing uniformity of the raw materials by granulation, thereby laying a foundation for preparing the packaging film with balanced performance.

[0040] 3. The present application can not only improve the smoothness of the film surface, but also reduce the precipitation by using specific opening agents and slip agents, which can not only maintain the long-term performance, but also reduce the pollution of the precipitates to the packaging material.

[0041] 4. The present application has a unique concept, which improves the plasticity of the raw materials by improving the raw material formula, can blow the packaging film with excellent mechanical properties and wear resistance and rubbing resistance, improves the reliability of liquid transportation in the container, and is convenient for popularization and application in the industry. DETAILED DESCRIPTION

[0042] The present application will be further described in detail in combination with specific embodiments.

[0043] Referring to the present application in use, the side close to the packaged material is defined as the inner side, and the other side away from the packaged material is correspondingly defined as the outer side. Example 1

[0044] The wear-resistant packaging film for the liquid container bag is prepared by the following steps:

[0045] (1) Preparing the first special material: mixing 8 parts by mass of the blow molding grade TPU with 0.5 parts by mass of the slip agent to obtain the first mixture, and granulating the first mixture to obtain the first special material; the blow molding grade TPU used can be TPU with the brand 1195A of BASF Company in Germany, and other brands of TPU with a melting temperature of 170-240℃ can also be used. TPU is a thermoplastic elastomer, which is a plastic material that can repeatedly soften at a certain temperature.

[0046] (2) Preparation of the second special material: 8.5 parts by mass of the first metallocene linear low density polyethylene is mixed with 0.3 parts by mass of PPA to obtain a second mixture, and the second mixture is granulated to obtain the second special material. The first metallocene linear low density polyethylene is MLLDPE with the brand XP8784ML from Exxon Mobil Corporation.

[0047] (3) Preparation of the third special material: 5 parts by mass of the second metallocene linear low density polyethylene, 1 part by mass of the first low density polyethylene, 0.3 parts by mass of PPA, 0.5 parts by mass of the opening agent and 0.5 parts by mass of the slip agent are mixed to obtain a third mixture, and the third mixture is granulated to obtain the third special material. The second metallocene linear low density polyethylene has lateral first long branches, and the first low density polyethylene has lateral second long branches. The first long branches and the second long branches are branches containing more than 3 carbons, such as isobutylene. The combination of the second metallocene linear low density polyethylene and the first low density polyethylene can not only enhance the mechanical properties of the film, but also improve the heat sealing strength of the film, thereby enhancing the overall strength of the bag obtained by heat sealing. Specifically, the second metallocene linear low density polyethylene can be MLLDPE with the brand 2005 from Exxon Mobil Corporation, and the first low density polyethylene can be LDPE with the brand 105BR from Exxon Mobil Corporation. The carrier of the opening agent used is second low density polyethylene, and the effective component is artificial spherical silica. The particle size of the spherical silica is 5 μm. The brand of the second low density polyethylene can be the same as or different from that of the first low density polyethylene, and there is no obvious difference in application effect. The carrier of the slip agent used is linear low density polyethylene with a melt index of 2, and the effective component is erucamide.

[0048] (4) Film preparation: the first special material prepared in step (1), the second special material prepared in step (2) and the third special material prepared in step (3) are co-extrusion blown to form a packaging film with an outer layer, a middle layer and an inner layer arranged in turn from the outside to the inside. The extrusion temperature of the outer layer is 185°C, the extrusion temperature of the middle layer is 180°C, and the extrusion temperature of the inner layer is 180°C. In this way, a wear-resistant packaging film with a thickness of 110-120 μm is obtained, and the thickness ratio of the outer layer, the middle layer and the inner layer is 1:2:1.

[0049] The PPA described above is a processing aid that can enhance the plasticizing property of the raw material, make it suitable for the blowing process, eliminate sharkskin and water marks caused by melt fracture, reduce crystal points caused by equipment and raw material factors, and improve the brightness and flatness of the film surface. The processing aid with the brand PEA-3S from Huayi-Weibao Packaging Additive Co., Ltd. can be selected. Example Two

[0050] The difference between this example and Example One is that:

[0051] In step (1), the first mixture was obtained by mixing 9 parts by mass of the blow molding grade TPU with 1 part by mass of the slip agent.

[0052] In step (2), the second mixture was obtained by mixing 9.5 parts by mass of the first metallocene linear low density polyethylene with 0.5 parts by mass of the PPA.

[0053] In step (3), the third mixture was obtained by mixing 6 parts by mass of the second metallocene linear low density polyethylene, 1.5 parts by mass of the first low density polyethylene, 0.5 parts by mass of the PPA, 1 part by mass of the opening agent, and 1 part by mass of the slip agent. The particle size of the spherical silica was 6.5 μm.

[0054] In step (4), the extrusion temperature of the outer layer was 190°C, the extrusion temperature of the intermediate layer was 183°C, and the extrusion temperature of the inner layer was 185°C. A wear-resistant packaging film having a thickness of 115 μm was prepared.

[0055] The rest was the same as in Example One. Example Three

[0056] The difference between this example and Example One is that:

[0057] In step (1), the first mixture was obtained by mixing 10 parts by mass of the blow molding grade TPU with 1.5 parts by mass of the slip agent.

[0058] In step (2), the second mixture was obtained by mixing 10.5 parts by mass of the first metallocene linear low density polyethylene with 0.7 parts by mass of the PPA.

[0059] In step (3), the third mixture was obtained by mixing 7 parts by mass of the second metallocene linear low density polyethylene, 2 parts by mass of the first low density polyethylene, 0.7 parts by mass of the PPA, 1.5 parts by mass of the opening agent, and 1.5 parts by mass of the slip agent. The particle size of the spherical silica was 8 μm.

[0060] In step (4), the extrusion temperature of the outer layer was 195°C, the extrusion temperature of the intermediate layer was 185°C, and the extrusion temperature of the inner layer was 190°C. A wear-resistant packaging film having a thickness of 120 μm was prepared.

[0061] The rest was the same as in Example One. Example Four

[0062] The difference between this example and Example One is that:

[0063] In step (1), the first mixture was obtained by mixing 8 parts by mass of the blow molding grade TPU with 1.5 parts by mass of the slip agent.

[0064] In step (2), the second mixture was obtained by mixing 8.5 parts by mass of the first metallocene linear low density polyethylene with 0.7 parts by mass of the PPA.

[0065] In step (3), the third mixture was obtained by mixing 5 parts by mass of the second metallocene linear low density polyethylene, 2 parts by mass of the first low density polyethylene, 0.7 parts by mass of the PPA, 0.5 parts by mass of the opening agent and 0.5 parts by mass of the slip agent. The particle size of the spherical silica was 6 μm.

[0066] In step (4), the extrusion temperature of the outer layer was 187°C, the extrusion temperature of the middle layer was 184°C, and the extrusion temperature of the inner layer was 182°C. A wear-resistant packaging film with a thickness of 112 μm was prepared.

[0067] The rest was the same as in Example One. Example Five

[0068] The difference between this example and Example One is that:

[0069] In step (1), the first mixture was obtained by mixing 10 parts by mass of the blow molding grade TPU and 0.5 parts by mass of the slip agent.

[0070] In step (2), the second mixture was obtained by mixing 10.5 parts by mass of the first metallocene linear low density polyethylene and 0.3 parts by mass of the PPA.

[0071] In step (3), the third mixture was obtained by mixing 7 parts by mass of the second metallocene linear low density polyethylene, 1 part by mass of the first low density polyethylene, 0.3 parts by mass of the PPA, 1.5 parts by mass of the opening agent and 1.5 parts by mass of the slip agent. The particle size of the spherical silica was 7 μm.

[0072] In step (4), the extrusion temperature of the outer layer was 192°C, the extrusion temperature of the middle layer was 182°C, and the extrusion temperature of the inner layer was 188°C. A wear-resistant packaging film with a thickness of 118 μm was prepared.

[0073] The rest was the same as in Example One.

[0074] Comparative Example

[0075] A packaging film was prepared via the following steps:

[0076] (1) Preparation of special material: 5 parts by mass of metallocene linear low density polyethylene, 1 part by mass of low density polyethylene and 0.5 parts by mass of slip agent were mixed to prepare the special material. The metallocene linear low density polyethylene used was MLLDPE with the trade name 1018MA from Exxon Mobil Company, and the low density polyethylene was LDPE with the trade name 2426H from Daqing Petrochemical Company.

[0077] (2) Film preparation: the special material prepared in step (1) is divided into three parts and placed in three hoppers of a multi-layer co-extrusion machine, and a packaging film with an outer layer, a middle layer and an inner layer arranged from outside to inside is prepared by co-extrusion blowing, and the extrusion temperature of the outer layer, the middle layer and the inner layer is 180 DEG C. Thus, a wear-resistant packaging film with a thickness of 120 microns is prepared, and the thickness ratio of the outer layer, the middle layer and the inner layer is 1:2:1.

[0078] The packaging film prepared in the above examples is tested in terms of tensile strength, tear strength, elongation, puncture resistance, falling weight, heat sealing strength, rubbing resistance and abrasion amount, and compared with the packaging film prepared in the comparative example. Among them, the tensile strength test is carried out in accordance with the ASTM standard "D 882-02 Test Method for Tensile Properties of Thin Plastic Sheet", the tear strength test is carried out in accordance with the ASTM standard "D 1004-13 American Standard for Testing Materials", the puncture resistance test is carried out in accordance with the national standard "GB / T 37841-2019 Test Method for Puncture Resistance of Plastic Film and Sheet", the flat falling weight impact test is carried out in accordance with the national standard "GB / T 9639.1-2008 Test Method for Impact Resistance of Plastic Film and Sheet by Free Falling Weight Method Part 1: Staircase Method", the heat sealing strength is carried out in accordance with the line standard "QB / T 2358-1998 Test Method for Heat Sealing Strength of Plastic Film Packaging Bag", the rubbing resistance is carried out in accordance with the line standard "QB / T 5787-2022 Test Method for Rubbing Resistance of Plastic Film", and the abrasion amount is carried out in accordance with the national standard "GBT 40797-2021 Determination of Abrasion Resistance of Vulcanized Rubber or Thermoplastic Rubber by Vertical Drive Abrasion Paddle Method". The test results are as follows:

[0079]

[0080] It can be seen that the packaging film prepared in the present application has improved tensile strength, tear strength, puncture resistance, elongation, falling weight and heat sealing strength compared with the comparative example under the premise of the same thickness, number of layers and thickness of each layer, which can meet the mechanical property requirements of the liquid bag, especially the rubbing resistance and abrasion amount, which can better serve the actual transportation of liquid.

[0081] The prepared packaging film can also be heat sealed into a liquid bag for packaging use.

[0082] The raw material composition expressed in the present application is the main raw material, that is, the raw material with a percentage of more than 99.5% in the total mass of the raw material, and other trace auxiliary materials can also be included. That is, if the percentage of the added auxiliary material in the total mass of the raw material does not exceed 0.5% based on the raw material composition expressed in the present application, it still belongs to the protection scope of the present application.

[0083] The above merely describes preferred embodiments of the present application, but is not intended to limit the present application to other forms, and any person skilled in the art can make changes or modifications to the above disclosed technical contents into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution content of the present application and according to the technical essence of the present application still belongs to the protection scope of the technical solution of the present application.

Claims

1. A kind of packing film of blow wear-resistant packaging film for liquid bag, comprising film body, the film body is successively made of outer layer, middle layer and inner layer from outside to inside; It is characterized by: The outer layer is made of the following mass parts of raw materials: Blow molding grade TPU 8 ~ 10 parts Slip agent 0.5 ~ 1.5 parts The carrier of slip agent is linear low density polyethylene with melt index of 2 g / 10min, and the effective component is erucic acid amide; The middle layer is made of the following mass parts of raw materials: First metallocene linear low density polyethylene 8.5 ~ 10.5 parts PPA processing aid 0.3 ~ 0.7 parts The inner layer is made of the following mass parts of raw materials: Second metallocene linear low density polyethylene 5 ~ 7 parts First low density polyethylene 1 ~ 2 parts PPA processing aid 0.3 ~ 0.7 parts Opening agent 0.5 ~ 1.5 parts Slip agent 0.5 ~ 1.5 parts The melting temperature of the blow molding grade TPU is 170 ~ 240 ℃, the first metallocene linear low density polyethylene is XP8784ML, the second metallocene linear low density polyethylene has a first long side chain, the first low density polyethylene has a second long side chain, the PPA processing aid is PEA-3S, the second metallocene linear low density polyethylene is 2005, and the first low density polyethylene is 105BR.

2. The blown abrasion-resistant packaging film for liquid-tote bags according to claim 1, characterized in that: The carrier of the opening agent is second low density polyethylene, and the effective component is artificially synthesized spherical silicon dioxide.

3. The blown abrasion-resistant packaging film for liquid-tote bags according to claim 2, characterized in that: Both the first long side chain and the second long side chain are branched chains with more than 3 carbons.

4. The blown abrasion-resistant packaging film for liquid-tote bags according to any one of claims 1 to 3, characterized in that: The thickness of the film body is 110 ~ 120 μm.

5. The blown abrasion-resistant packaging film for liquid-tote bags according to claim 4, characterized in that: The thickness ratio of the outer layer, the middle layer and the inner layer is 1:2:

1.

6. A process for the production of a blown wear resistant packaging film for liquid bag-in-box, characterized by: It comprises the following steps: (1) preparing the first special material: mixing 8 ~ 10 mass parts of blow molding grade TPU with 0.5 ~ 1.5 mass parts of slip agent to obtain a first mixture; the melting temperature of the blow molding grade TPU is 170 ~ 240 ℃, and the carrier of the slip agent is linear low density polyethylene with melt index of 2 g / 10min, and the effective component is erucic acid amide; (2) preparing the second special material: mixing 8.5 ~ 10.5 mass parts of first metallocene linear low density polyethylene with 0.3 ~ 0.7 mass parts of PPA processing aid to obtain a second mixture; the first metallocene linear low density polyethylene is XP8784ML; (3) preparing the third special material: mixing 5 ~ 7 mass parts of second metallocene linear low density polyethylene, 1 ~ 2 mass parts of first low density polyethylene, 0.3 ~ 0.7 mass parts of PPA processing aid, 0.5 ~ 1.5 mass parts of opening agent and 0.5 ~ 1.5 mass parts of slip agent to obtain a third mixture; the second metallocene linear low density polyethylene has a first long side chain, the first low density polyethylene has a second long side chain, the second metallocene linear low density polyethylene is 2005, and the first low density polyethylene is 105BR; (4) film preparation: co-extrusion blowing the first mixture prepared in step (1), the second mixture prepared in step (2) and the third mixture prepared in step (3) to form the outer layer, the middle layer and the inner layer arranged successively from outside to inside of the packaging film. The PPA processing agent used is PEA-3S.

7. The method of producing a blown wear-resistant packaging film for liquid bags according to claim 6, characterized in that: The carrier of the opening agent is second low-density polyethylene, and the effective component is artificial synthetic spherical silicon dioxide.

8. A process for the production of a blown wear resistant packaging film for liquid bags according to claim 6 or 7, characterized in that: The first mixture of step (1), the second mixture of step (2) and the third mixture of step (3) are all granulated and then enter step (4).

9. The method of producing a blown wear-resistant packaging film for liquid bags according to claim 8, characterized in that: In step (4), the extrusion temperature of the outer layer is 185-195℃, the extrusion temperature of the middle layer is 180-185℃, and the extrusion temperature of the inner layer is 180-190℃.

10. A liquid container bag comprising a bag body which is heat-sealed from a polyethylene film, characterized by: The polyethylene film is a packaging film prepared by the method of any one of claims 1 to 5 or any one of claims 6 to 9.

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