A cold-resistant and drop-resistant packaging material and a preparation method thereof

Abstract

The application belongs to the technical field of packaging materials, and particularly relates to a freezing-resistant and drop-resistant packaging material and a preparation method thereof. The packaging material is prepared by dry compounding of a BOPA printing film and a milky white PE film; the BOPA printing film is prepared by printing of a BOPA film layer, and the milky white PE film is prepared by film blowing of a PE resin layer; the PE resin layer comprises a corona layer, an intermediate layer and a heat sealing layer, and the corona layer is connected with a printing layer of the BOPA printing film. Through the research on the PE resin and the optimization design of the PE formula, the packaging film still has excellent puncture resistance and drop resistance at a very low temperature of-18 DEG C, and the problem of broken packages in the transportation and handling process of goods is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a cold-resistant and drop-resistant packaging material and its preparation method. Background Technology

[0002] In recent years, my country's construction industry has developed rapidly, with infrastructure projects increasing across the country. As a result, the demand for waterproof coatings, which serve as external protection for building materials, has also been increasing. Among them, waterproof powder coatings are similar to cement powders and are usually packaged in films, with each package typically weighing around 4 kg.

[0003] Waterproof powder packaging materials on the market are typically subjected to rough handling during distribution and transportation. Dust and sand may be present on the ground during drops, thus requiring high drop resistance and puncture resistance in the packaging materials. Otherwise, bags are prone to breakage and leakage. Especially in cold winters, particularly in northern regions where temperatures can reach -18°C, the extreme cold can reduce the overall toughness, puncture resistance, and drop resistance of the packaging. This can lead to irregular damage to the bag surface and heat seal during distribution and drops, with a high breakage rate of around 10%, failing to adequately protect the contents.

[0004] Therefore, there is an urgent need for a packaging material that is resistant to freezing and drops, and its preparation method, to solve the above problems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a freeze-resistant and drop-resistant packaging material and its preparation method. This freeze-resistant and drop-resistant packaging material and its preparation method enable the packaging film to maintain excellent puncture and drop resistance even at extremely low temperatures of -18°C.

[0006] To achieve one of the objectives of this invention, this invention provides a packaging material that is resistant to freezing and drops. This packaging material is made by dry lamination of BOPA printed film and milky white PE film. The BOPA printed film is made by printing BOPA film layers, and the milky white PE film is made by blowing PE resin layers. The PE resin layers include a corona layer, an intermediate layer, and a heat-sealing layer, and the corona layer is connected to the printed layer of the BOPA printed film.

[0007] Preferably, the corona layer comprises 45-50 parts by weight of a first metallocene polyethylene, 49.7-54.7 parts by weight of a metallocene linear low-density polyethylene, and 0.3 parts by weight of a processing aid; the intermediate layer comprises 45-50 parts by weight of a first metallocene polyethylene, 36.7-41.7 parts by weight of a metallocene linear low-density polyethylene, 0.3 parts by weight of a processing aid, and 13 parts by weight of a white masterbatch; the heat-sealing layer comprises 31.7-36.7 parts by weight of a second metallocene polyethylene, 60-65 parts by weight of a metallocene linear polyethylene, 1 part by weight of a processing aid, 2 parts by weight of an opening agent, and 0.3 parts by weight of a slip agent.

[0008] Preferably, the corona layer comprises 50 parts by weight of a first metallocene polyethylene, 49.7 parts by weight of a metallocene linear low-density polyethylene, and 0.3 parts by weight of a processing aid; the intermediate layer comprises 50 parts by weight of a first metallocene polyethylene, 36.7 parts by weight of a metallocene linear low-density polyethylene, 0.3 parts by weight of a processing aid, and 13 parts by weight of a white masterbatch; and the heat-sealing layer comprises 36.7 parts by weight of a second metallocene polyethylene, 60 parts by weight of a metallocene linear polyethylene, 0.3 parts by weight of a processing aid, 2 parts by weight of an opening agent, and 1 part by weight of a slip agent.

[0009] Preferably, the first metallocene polyethylene is TH60 manufactured by Dow Chemical Company; the metallocene linear low-density polyethylene is XP6056ML manufactured by ExxonMobil; the processing aid is 10991-K manufactured by Anpeise Company; the white masterbatch is W6080J manufactured by Juxing Company; the second metallocene polyethylene is PL1881G manufactured by Dow Chemical Company; the metallocene linear polyethylene is EXCEED 1018FA manufactured by ExxonMobil; the opening agent is AB-20LD manufactured by Beijing Yalun Company; and the slip agent is 10090-K manufactured by Anpeise Company.

[0010] Preferably, the thickness ratio of the corona layer, the intermediate layer, and the heat-sealing layer is 30:45:30.

[0011] Preferably, the total thickness of the packaging material is 120 μm, the thickness of the milky white PE film is 105 μm, and the thickness of the BOPA printing film is 15 μm.

[0012] To achieve the second objective of this invention, this invention provides a method for preparing a freeze-resistant and drop-resistant packaging material, the method comprising the following steps: S1. Weigh out the corresponding weight parts of the heat-sealing layer, intermediate layer and corona layer ingredients according to the formula; S2. The corona layer, intermediate layer and heat seal layer are processed sequentially through high temperature plasticization → extrusion → blow-blowing → air cooling and shaping → thickness measurement → clamping bubble de-bubbling → traction → corona treatment → slitting and winding to obtain the required milky white PE film. S3. The obtained milky white PE film is dry-laminated with BOPA printed film to obtain the required freeze-resistant and drop-resistant packaging material.

[0013] Preferably, in step S3, the amount of adhesive applied is 2.5-3.2 g / m²; the first unwinding tension is 60 N; and the second unwinding tension is 70 N.

[0014] Preferably, in step S2, the high-temperature plasticizing temperature is 187-195℃.

[0015] The advantages of this invention compared to the prior art are as follows: 1) This invention improves the formulation of packaging materials for waterproof powder packaging by adding metallocene ethylene-octene copolymer PE (grade TH60) and metallocene ethylene-hexene copolymer PE (grade XP6056ML), which have excellent performance after freezing. This satisfies the requirements of the packaging material for freezing resistance and drop resistance. That is, even at a low temperature of around -18℃, the frozen packaging material can still maintain stable performance. The drop resistance, puncture resistance, heat seal strength and other indicators can meet the stringent requirements of passage and drop resistance. This greatly improves the problem of package breakage during passage and handling (package breakage includes rupture of the film surface and heat seal). The breakage rate is greatly reduced and can be controlled at around 2‰, so that the contents are fully protected at extremely low temperatures.

[0016] 2) This invention, through the design of a three-layer PE formulation and the selection of freeze-resistant resins (TH60 and XP6056ML), enables the film to maintain good performance at -18℃, thereby ensuring the film's drop resistance under freezing conditions. Specifically, Corona layer: Exxon's metallocene PE (grade XP6056ML), an ethylene-hexene copolymer, is used. It possesses extremely high tensile and impact resistance, and its lamination with BOPA printed film enhances composite strength. Dow's metallocene PE (grade TH60), an ethylene-octene copolymer, exhibits excellent toughness and sealing properties, particularly outstanding low-temperature toughness and flexural crack resistance at low temperatures. It also possesses strong processability, meeting the demands of demanding freezing applications. An color-matching processing aid (grade 10991-K) further improves processability.

[0017] Intermediate Layer: Similar to the corona layer, Exxon's metallocene PE (grade XP6056ML) and Dow's TH60 are added, giving the film excellent low-temperature toughness and ultra-high tensile and puncture resistance. Through continuous screening, Juxing's white masterbatch W6080J was added. Unlike typical white masterbatches that use high-density HDPE as a carrier, this one uses low-density LDPE as a carrier, resulting in superior resistance to flexural cracking at low temperatures compared to typical white masterbatches. Grade 10991-K is a color-matching processing aid that improves processing performance.

[0018] Heat-sealing layer: The heat-sealing layer uses Dow Chemical's metallocene PE (grade PL1881G), which is an ethylene-octene copolymer with excellent low-temperature heat-sealing performance and drop resistance. Exxon's metallocene linear polyethylene (grade EXCEED 1018FA) has outstanding tensile strength, impact strength and puncture resistance, as well as a lower heat-sealing temperature. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] A method for developing a cold-resistant and drop-resistant packaging material, wherein the packaging material is made by dry lamination of BOPA printed film and milky white PE film; the BOPA printed film is made by printing BOPA film layers, and the milky white PE film is made by blowing PE resin layers; the PE resin layers include a corona layer, an intermediate layer and a heat-sealing layer, and the corona layer is connected to the printed layer of the BOPA printed film.

[0022] The corona layer comprises 45-50 parts by weight of first metallocene polyethylene, 49.7-54.7 parts by weight of metallocene linear low-density polyethylene, and 0.3 parts by weight of processing aid; the intermediate layer comprises 45-50 parts by weight of first metallocene polyethylene, 36.7-41.7 parts by weight of metallocene linear low-density polyethylene, 0.3 parts by weight of processing aid, and 13 parts by weight of white masterbatch; the heat-sealing layer comprises 31.7-36.7 parts by weight of second metallocene polyethylene, 60-65 parts by weight of metallocene linear polyethylene, 1 part by weight of processing aid, 2 parts by weight of opening agent, and 0.3 parts by weight of slip agent.

[0023] The first metallocene polyethylene is TH60 manufactured by Dow Chemical Company; the metallocene linear low-density polyethylene is XP6056ML manufactured by ExxonMobil; the processing aid is 10991-K manufactured by Anpeise Company; the white masterbatch is W6080J manufactured by Juxing Company; the second metallocene polyethylene is PL1881G manufactured by Dow Chemical Company; the metallocene linear polyethylene is EXCEED 1018FA manufactured by ExxonMobil; the opening agent is AB-20LD manufactured by Beijing Yalun Company; and the slip agent is 10090-K manufactured by Anpeise Company.

[0024] A method for preparing a freeze-resistant and drop-resistant packaging material, the specific steps of which are as follows: S1. Weigh out the corresponding weight parts of the heat-sealing layer, intermediate layer and corona layer ingredients according to the formula; S2. The corona layer, intermediate layer and heat seal layer are processed sequentially through high temperature plasticization → extrusion → blow-blowing → air cooling and shaping → thickness measurement → clamping bubble de-bubbling → traction → corona treatment → slitting and winding to obtain the required milky white PE film. S3. The obtained milky white PE film is dry-laminated with BOPA printed film to obtain the required freeze-resistant and drop-resistant packaging material.

[0025] The process parameters for preparing milky white PE film are shown in Table 1 below: Table 1

[0026] Example 1

[0027] S1. Weigh the corresponding weight parts of the heat-sealing layer, intermediate layer and corona layer according to the formula; The corona layer comprises 45 parts by mass of first metallocene polyethylene, 54.7 parts by mass of metallocene linear low-density polyethylene, and 0.3 parts by mass of processing aid; the intermediate layer comprises 45 parts by mass of first metallocene polyethylene, 41.7 parts by mass of metallocene linear low-density polyethylene, 0.3 parts by mass of processing aid, and 13 parts by mass of white masterbatch; the heat-sealing layer comprises 31.7 parts by mass of second metallocene polyethylene, 65 parts by mass of metallocene linear polyethylene, 1 part by mass of processing aid, 2 parts by mass of opening agent, and 0.3 parts by mass of slip agent.

[0028] S2. The corona layer, intermediate layer and heat seal layer are processed sequentially through high temperature plasticization → extrusion → blow-blowing → air cooling and shaping → thickness measurement → clamping bubble de-bubbling → traction → corona treatment → slitting and winding to obtain the required milky white PE film. S3. The obtained milky white PE film is dry-laminated with BOPA printed film to obtain the required freeze-resistant and drop-resistant packaging material 1.

[0029] Example 2

[0030] S1. Weigh the corresponding weight parts of the heat-sealing layer, intermediate layer and corona layer according to the formula; The corona layer comprises 50 parts by mass of first metallocene polyethylene, 49.7 parts by mass of metallocene linear low-density polyethylene, and 0.3 parts by mass of processing aid; the intermediate layer comprises 50 parts by mass of first metallocene polyethylene, 36.7 parts by mass of metallocene linear low-density polyethylene, 0.3 parts by mass of processing aid, and 13 parts by mass of white masterbatch; the heat-sealing layer comprises 36.7 parts by mass of second metallocene polyethylene, 60 parts by mass of metallocene linear polyethylene, 0.3 parts by mass of processing aid, 2 parts by mass of opening agent, and 1 part by mass of slip agent.

[0031] S2. The corona layer, intermediate layer and heat seal layer are processed sequentially through high temperature plasticization → extrusion → blow-blowing → air cooling and shaping → thickness measurement → clamping bubble de-bubbling → traction → corona treatment → slitting and winding to obtain the required milky white PE film. S3. The obtained milky white PE film is dry-laminated with BOPA printed film to obtain the required freeze-resistant and drop-resistant packaging material 2.

[0032] Example 3

[0033] S1. Weigh the corresponding weight parts of the heat-sealing layer, intermediate layer and corona layer according to the formula; The corona layer comprises 47 parts by mass of first metallocene polyethylene, 52.7 parts by mass of metallocene linear low-density polyethylene, and 0.3 parts by mass of processing aid; the intermediate layer comprises 47 parts by mass of first metallocene polyethylene, 39.7 parts by mass of metallocene linear low-density polyethylene, 0.3 parts by mass of processing aid, and 13 parts by mass of white masterbatch; the heat-sealing layer comprises 33.7 parts by mass of second metallocene polyethylene, 63 parts by mass of metallocene linear polyethylene, 1 part by mass of processing aid, 2 parts by mass of opening agent, and 0.3 parts by mass of slip agent.

[0034] S2. The corona layer, intermediate layer and heat seal layer are processed sequentially through high temperature plasticization → extrusion → blow-blowing → air cooling and shaping → thickness measurement → clamping bubble de-bubbling → traction → corona treatment → slitting and winding to obtain the required milky white PE film. S3. The obtained milky white PE film is dry-laminated with BOPA printed film to obtain the required freeze-resistant and drop-resistant packaging material 3.

[0035] Comparative Example 1

[0036] Packaging material for traditional waterproof powder packaging is referred to as packaging material 4.

[0037] Packaging materials 1-4 were placed in a freezer set to -18°C for half an hour. Afterward, the packaging materials were removed and their performance was tested. The results are shown in Table 2 below: Table 2

[0038] The specific method of the drop test is as follows: 50 bags are randomly sampled, each containing 4 kg of powder, and dropped from a height of 2 meters six times (front, back, up, down, left, and right) to observe the bag breakage.

[0039] As shown in Table 2 above, the packaging materials prepared in Examples 1-3 of this invention did not experience any breakage after drop test, while Comparative Example 1 (i.e., the packaging material of existing waterproof materials) showed breakage at different locations after drop test. Therefore, the packaging materials prepared in this invention have superior drop resistance compared to existing packaging materials. The puncture strength of the packaging materials prepared in Examples 1-3 of this invention is 9.5-10.3 N, while the puncture strength of the packaging material of Comparative Example 1 is 7.2 N. Therefore, the puncture resistance of the packaging materials prepared in this invention is far superior to that of existing packaging materials.

Claims

1. A packaging material that is resistant to freezing and drops, characterized in that, The packaging material is made by dry lamination of BOPA printed film and milky white PE film; the BOPA printed film is made by printing BOPA film layers, and the milky white PE film is made by blowing PE resin layers; the PE resin layers include a corona layer, an intermediate layer and a heat-sealing layer, and the corona layer is connected to the printed layer of the BOPA printed film. The corona layer comprises 45-50 parts by weight of a first metallocene polyethylene, 49.7-54.7 parts by weight of a metallocene linear low-density polyethylene, and 0.3 parts by weight of a processing aid; the intermediate layer comprises 45-50 parts by weight of a first metallocene polyethylene, 36.7-41.7 parts by weight of a metallocene linear low-density polyethylene, 0.3 parts by weight of a processing aid, and 13 parts by weight of a white masterbatch; the heat-sealing layer comprises 31.7-36.7 parts by weight of a second metallocene polyethylene, 60-65 parts by weight of a metallocene linear polyethylene, 1 part by weight of a processing aid, 2 parts by weight of an opening agent, and 0.3 parts by weight of a slip agent; The first metallocene polyethylene is TH60 manufactured by Dow Chemical Company; the metallocene linear low-density polyethylene is XP6056ML manufactured by ExxonMobil; the processing aid is 10991-K manufactured by Anpeise Chemical Company; the white masterbatch is W6080J manufactured by Juxing Chemical Company; the second metallocene polyethylene is PL1881G manufactured by Dow Chemical Company; the metallocene linear polyethylene is EXCEED 1018FA manufactured by ExxonMobil; the opening agent is AB-20LD manufactured by Beijing Yalen Chemical Company; and the slip agent is 10090-K manufactured by Anpeise Chemical Company.

2. The packaging material resistant to freezing and drops according to claim 1, characterized in that, The corona layer comprises 50 parts by weight of a first metallocene polyethylene, 49.7 parts by weight of a metallocene linear low-density polyethylene, and 0.3 parts by weight of a processing aid; the intermediate layer comprises 50 parts by weight of a first metallocene polyethylene, 36.7 parts by weight of a metallocene linear low-density polyethylene, 0.3 parts by weight of a processing aid, and 13 parts by weight of a white masterbatch; the heat-sealing layer comprises 36.7 parts by weight of a second metallocene polyethylene, 60 parts by weight of a metallocene linear polyethylene, 0.3 parts by weight of a processing aid, 2 parts by weight of an opening agent, and 1 part by weight of a slip agent.

3. The packaging material resistant to freezing and drops according to claim 1, characterized in that, The thickness ratio of the corona layer, intermediate layer and heat seal layer is 30:45:

30.

4. The packaging material resistant to freezing and drops according to claim 1, characterized in that, The total thickness of the packaging material is 120 μm, the thickness of the milky white PE film is 105 μm, and the thickness of the BOPA printing film is 15 μm.

5. A method for preparing a freeze-resistant and drop-resistant packaging material as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: S1. Weigh out the corresponding weight parts of the heat-sealing layer, intermediate layer and corona layer ingredients according to the formula; S2. The corona layer, intermediate layer and heat-sealing layer are sequentially processed through high-temperature plasticization → extrusion → blow-blowing → air-cooling and shaping → thickness measurement → clamping bubble de-bubbling → traction → corona treatment → slitting and winding to obtain the desired milky white PE film. S3. The obtained milky white PE film is dry-laminated with BOPA printed film to obtain the required freeze-resistant and drop-resistant packaging material.

6. The method for preparing a freeze-resistant and drop-resistant packaging material according to claim 5, characterized in that, In step S3, the amount of adhesive applied is 2.5-3.2 g / m²; the first unwinding tension is 60 N; and the second unwinding tension is 70 N.

7. The method for preparing a freeze-resistant and drop-resistant packaging material according to claim 5, characterized in that, In step S2, the high-temperature plasticizing temperature is 187-195℃.

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