Heat-shrinkable cushion packaging air cushion film and manufacturing method thereof

Abstract

The present invention relates to the technical field of packaging materials, and in particular to a heat-shrinkable cushioning packaging air cushion film and a method for manufacturing the same. The film is co-extruded from at least five layers, and the five-layer structure includes an outer layer, a sub-outer layer, a core layer, a sub-inner layer and an inner layer from the outside to the inside; the components of the outer layer include polyethylene terephthalate-1,4-cyclohexanedimethanol; the sub-outer layer is made of modified pellets, and the components of the modified pellets include polyethylene terephthalate-1,4-cyclohexanedimethanol, GMA modified adhesive and linear low-density polyethylene; the components of the core layer include low-density polyethylene. The film provided by the present invention, after being made into a cushioning air cushion bag, not only has good barrier properties but also has a heat shrinkage effect. After the air cushion bag is inflated and heat-sealed, the packaged object is placed in the bag, and then heated for a short time, the film can wrap and protect the packaged object in all directions without dead angles, and has a particularly good wrapping effect on special-shaped products.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging materials, in particular to a heat-shrinkable cushion packaging air cushion film and a manufacturing method thereof. Background Art

[0002] In the logistics and transportation industries, product packaging and protection are crucial. Traditional packaging materials, such as foam and pulp molding, while effective at cushioning, have limitations in terms of environmental friendliness, cost, and efficiency. With the advancement of plastic packaging technology, air cushion film, as a lightweight, efficient, and recyclable packaging material, is gaining widespread market adoption.

[0003] Currently, cushioning films for packaging are primarily made from PE (polyethylene) or PE / PA (polyethylene / nylon) co-extruded blown films. These materials possess excellent mechanical and barrier properties, effectively protecting products from impact and moisture. However, because these materials lack heat shrinkage, gaps often form between the film and the product during packaging. This not only affects the compactness and aesthetics of the packaging, but can also cause product movement during transportation, reducing the packaging's protective effectiveness.

[0004] Therefore, there is still significant room for improvement in existing heat-shrinkable air cushion films, including manufacturing processes, material selection, and performance enhancements. For example, ensuring uniformity during the heat shrinking process to avoid film damage caused by uneven stress after shrinkage; maintaining or improving the film's barrier properties while ensuring heat shrinkage performance; and optimizing material formulations to reduce costs and improve environmental performance are all issues that the industry needs to further research and address.

[0005] Based on an in-depth analysis of existing technologies and an understanding of market demand, the present invention aims to provide a heat-shrinkable cushioning packaging air cushion film with superior performance to better meet the needs of modern logistics and transportation industries for efficient, environmentally friendly, economical and safe packaging solutions. Summary of the Invention

[0006] In order to solve the above-mentioned shortcomings in the heat shrinkage performance of the cushioning packaging air cushion film in the prior art, the present invention provides a heat-shrinkable cushioning packaging air cushion film and a manufacturing method thereof.

[0007] Specifically, one of the technical solutions provided by the present invention is as follows:

[0008] A heat-shrinkable cushioning packaging air cushion film, the film being co-extruded by at least five layers, the five layers comprising, from the outside to the inside, an outer layer, a sub-outer layer, a core layer, a sub-inner layer, and an inner layer;

[0009] The components of the outer layer include polyethylene terephthalate-1,4-cyclohexanedimethanol ester;

[0010] The components of the secondary outer layer include polyethylene terephthalate-1,4-cyclohexanedimethanol ester, GMA modified adhesive and linear low-density polyethylene;

[0011] The core layer comprises low density polyethylene.

[0012] In one embodiment, the polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer has a heat distortion temperature (HDT) of 65° C. or higher and 75° C. or lower as measured according to ASTM D648 (0.45 MPa); and / or

[0013] The specific gravity of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer is 1.25-1.28 g / cm 3 and / or

[0014] The haze of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer is less than 2%.

[0015] In one embodiment, the modified pelletized material comprises, by weight, 35-50 parts of polyethylene terephthalate-1,4-cyclohexanedimethanol, 10-20 parts of a GMA modified binder, and 35-55 parts of a linear low-density polyethylene; and / or

[0016] The specific gravity of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer is 1.25-1.28 g / cm 3 and / or

[0017] The haze of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer is less than 2%; and / or

[0018] The heat distortion temperature (HDT) of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer is less than 75° C. as measured according to ASTM D648 (0.45 MPa); and / or

[0019] The linear low-density polyethylene used in the secondary outer layer has a melt index of 1.0-2.0 g / min at 190°C.

[0020] In one embodiment, the low-density polyethylene used in the core layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or

[0021] The haze of the low-density polyethylene used in the core layer is less than 8%.

[0022] In one embodiment, the components of the secondary inner layer include polypropylene, low-density polyethylene, and vinyl polymer grafted polyether polyol.

[0023] In one embodiment, the components of the secondary inner layer include, by weight, 35-50 parts of polypropylene, 35-50 parts of low-density polyethylene, and 10-20 parts of vinyl polymer grafted polyether polyol; and / or

[0024] The polypropylene used in the secondary inner layer has a melt index of 1.0-2.0 g / min at 190°C; and / or

[0025] The haze of the polypropylene used in the secondary inner layer is less than 10%; and / or

[0026] The low-density polyethylene used in the secondary inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or

[0027] The haze of the low-density polyethylene used in the secondary inner layer is less than 8%; and / or

[0028] The vinyl polymer grafted polyether polyol used in the secondary inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or

[0029] The haze of the vinyl polymer grafted polyether polyol used in the secondary inner layer is less than 5%.

[0030] In one embodiment, the components of the inner layer include metallocene polyethylene, low-density polyethylene, talc masterbatch and erucamide.

[0031] In one embodiment, the components of the inner layer include, by weight, 50-60 parts of metallocene polyethylene, 30-50 parts of low-density polyethylene, 1-5 parts of talc masterbatch, and 0.5-1 part of erucamide;

[0032] The metallocene polyethylene used in the inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or

[0033] The haze of the metallocene polyethylene used in the inner layer is less than 20%; and / or

[0034] The low-density polyethylene used in the inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or

[0035] The haze of the low-density polyethylene used in the inner layer is less than 8%; and / or

[0036] The mesh size of the talc powder in the talc powder masterbatch used in the inner layer is 800-1200 mesh; and / or

[0037] The content of talc powder in the talc powder masterbatch used in the inner layer is 60%-70%.

[0038] In one embodiment, the thickness of the outer layer accounts for 30% to 35% of the total thickness; and / or

[0039] The thickness of the secondary outer layer accounts for 10% to 15% of the total thickness; and / or

[0040] The thickness of the core layer accounts for 10% to 15% of the total thickness; and / or

[0041] The thickness of the sub-inner layer accounts for 10% to 15% of the total thickness; and / or

[0042] The thickness of the inner layer accounts for 30% to 35% of the total thickness.

[0043] The second technical solution provided by the present invention is as follows:

[0044] The method for manufacturing the heat-shrinkable cushioning packaging air cushion film as described above comprises the following steps:

[0045] Providing outer layer components, modified pellets for preparing a sub-outer layer, core layer components, sub-inner layer components, and inner layer components;

[0046] The outer layer component includes polyethylene terephthalate-1,4-cyclohexanedimethanol; the modified pelletized component includes polyethylene terephthalate-1,4-cyclohexanedimethanol, GMA modified adhesive and linear low-density polyethylene; the core layer component includes low-density polyethylene;

[0047] The outer layer component, modified pellets for preparing the sub-outer layer, core layer component, sub-inner layer component and inner layer component are used as raw materials to carry out multi-layer co-extrusion blown film to form a heat-shrinkable cushioning packaging air cushion film.

[0048] Based on the above, compared with the prior art, the heat-shrinkable cushioning packaging air cushion film provided by the present invention has at least one of the following beneficial technical effects:

[0049] The heat-shrinkable cushioning packaging air cushion film provided by the present invention, when made into a cushioning air cushion bag, not only has excellent barrier properties but also has an excellent heat shrinkage effect. After the air cushion bag is inflated and heat-sealed, the packaged item is placed in the bag. After a short period of heating, the film can fully wrap and protect the packaged item without blind spots, especially for special-shaped products. Furthermore, due to the shrinkage effect, the volume of the air chamber in the film also shrinks, increasing the air cushion gas saturation and providing better cushioning and protective effects.

[0050] Other features and beneficial effects of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work. The positional relationships described in the drawings in the following description are based on the directions of the components drawn in the diagrams, unless otherwise specified.

[0052] Figure 1 A schematic structural diagram of a heat-shrinkable cushioning packaging air cushion film provided by one embodiment of the present invention;

[0053] Figure 2 Photos of the air cushion film products provided by the present invention in multiple styles and sizes;

[0054] Figure 3 This is a schematic diagram of the flattened cloth structure provided by the present invention.

[0055] Reference numerals:

[0056] 10, outer layer; 20, second outer layer; 30, core layer; 40, second inner layer; 50, inner layer. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0058] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those generally understood by ordinary technicians in the field to which the present invention belongs, and should not be understood as limiting the present invention; it should be further understood that the terms used in the present invention should be understood to have meanings consistent with the meanings of these terms in the context of this specification and in the relevant fields, and should not be understood in an idealized or overly formal sense, unless explicitly defined as such in the present invention.

[0059] One embodiment of the present invention provides a heat-shrinkable cushioning packaging air cushion film, please refer to Figure 1 The film is co-extruded by at least five layers, and the five layers include, from the outside to the inside, an outer layer 10, a sub-outer layer 20, a core layer 30, a sub-inner layer 40 and an inner layer 50;

[0060] The components of the outer layer include polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG); preferably, the polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer has a heat deformation temperature (HDT) measured according to ASTM D648 (0.45 MPa) of more than 65°C and less than 75°C; preferably, the polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer has a specific gravity of 1.25-1.28 g / cm 3 The specific gravity can be 1.25, 1.26, 1.27, 1.28 g / cm 3 , or a point value between any two of the above; preferably, the haze of polyethylene terephthalate-1,4-cyclohexanedimethanol ester used in the outer layer is less than 2%; preferably, the thickness of the outer layer accounts for 30% to 35% of the total thickness.

[0061] The outer layer uses a single polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG) material, which has the following main functions: First, polyethylene terephthalate-1,4-cyclohexanedimethanol has good barrier and gas retention properties, which can improve the gas retention performance of the product and the cushioning protection function of the material; second, polyethylene terephthalate-1,4-cyclohexanedimethanol has a high melting point. Placing it in the outer layer can effectively increase the temperature range of film bag making and inflation heat sealing. At higher bag making and inflation heat sealing temperatures, it can ensure that the inner layer of the film is heat-sealed while the outer layer is not burned; third, the outer layer has a certain rigidity, which can effectively improve the tensile strength of the film.

[0062] The secondary outer layer is made of modified pellets, and the components of the modified pellets include polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), GMA modified adhesive and linear low-density polyethylene (LLDPE); preferably, in parts by weight, the components of the modified pellets include: 35-50 parts of polyethylene terephthalate-1,4-cyclohexanedimethanol, 10-20 parts of GMA modified adhesive and 35-55 parts of linear low-density polyethylene; preferably, the specific gravity of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer is 1.25-1.28 g / cm 3 The specific gravity can be 1.25, 1.26, 1.27, 1.28 g / cm 3 , or any value between the above two; preferably, the haze of the polyethylene terephthalate-1,4-cyclohexanedimethanol ester used in the secondary outer layer is less than 2%; preferably, the heat distortion temperature (HDT) of the polyethylene terephthalate-1,4-cyclohexanedimethanol ester used in the secondary outer layer is less than 75°C as measured according to ASTM D648 (0.45 MPa); preferably, the thickness of the secondary outer layer accounts for 10% to 15% of the total thickness. Preferably, the melt index of the linear low-density polyethylene used in the secondary outer layer at 190°C is 1.0-2.0 g / min, and the melt index can specifically be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or any value between the above two; preferably, the haze of the linear low-density polyethylene used in the secondary outer layer can specifically be 3.3%.

[0063] The main function of this sub-outer layer is to bond the outer layer and the core layer together. This requires mixing and granulating three materials: polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), a GMA-modified adhesive, and linear low-density polyethylene (LLDPE). Because PETG and PE have poor compatibility and differ significantly in processing temperature, for example, during the processing of the sub-outer layer, the mixture of the three materials needs to be added to a twin-screw extruder for mixing and modification. Therefore, the processing temperature of this step must not exceed 220°C and must not be less than 180°C, otherwise it will easily cause the PETG to discolor and turn yellow.

[0064] In this regard, the present invention creatively chooses to modify the above components first and then use the obtained modified pellets as the secondary outer layer material instead of directly adding them to the blown film. On the one hand, direct addition without modification will lead to poor plasticization of the material, resulting in white spots, crystal points and blown film holes. More importantly, in order to achieve better plasticization and compatibility, it is necessary to modify it. The GMA modified adhesive mainly acts as a compatibilizer for PE and PETG. Under the action of the twin-screw modifier, PE and PETG can be well compatible together. Since the modified material contains both PE and PETG, it has good compatibility and bonding properties with both PE and PETG.

[0065] The components of the core layer include low-density polyethylene (LDPE); preferably, the low-density polyethylene used in the core layer has a melt index of 1.0-2.0 g / min at 190°C, and the melt index can specifically be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or a point value between any two of the above; preferably, the haze of the low-density polyethylene used in the core layer is less than 8%; more preferably, the haze of the low-density polyethylene used in the core layer is 6.5%; preferably, the thickness of the core layer accounts for 10% to 15% of the total thickness.

[0066] The main material of the core layer is low-density polyethylene (LDPE), which has the following two main functions: on the one hand, it is used to connect the sub-outer layer and the sub-inner layer; on the other hand, because LDPE has higher transparency and better heat shrinkage performance and better blown film processing performance than LLDPE, choosing LDPE as the middle layer material can effectively improve the overall performance of the heat-shrinkable cushioning packaging air cushion film.

[0067] The components of the sub-inner layer include polypropylene (PP), low-density polyethylene (LDPE) and vinyl polymer grafted polyether polyol (POP). Preferably, in parts by weight, the components of the sub-inner layer include 35-50 parts of polypropylene, 35-50 parts of low-density polyethylene and 10-20 parts of vinyl polymer grafted polyether polyol; preferably, the melt index of the polypropylene used in the sub-inner layer at 190°C is 1.0-2.0 g / min, and the melt index can specifically be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or any point value between the above two; preferably, the haze of the polypropylene used in the sub-inner layer is less than 10%; preferably, the melt index of the low-density polyethylene used in the sub-inner layer at 190°C is 1.0-2.0 g / min, and the melt index can specifically be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or any point value between two of the above; preferably, the haze of the low-density polyethylene used in the secondary inner layer is less than 8%; preferably, the melt index of the vinyl polymer grafted polyether polyol used in the secondary inner layer at 190°C is 1.0-2.0 g / min, and the melt index can specifically be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or any point value between two of the above; preferably, the haze of the vinyl polymer grafted polyether polyol used in the secondary inner layer is less than 5%; preferably, the thickness of the secondary inner layer accounts for 10% to 15% of the total thickness.

[0068] The components of the sub-inner layer contain polypropylene (PP), which is mainly used to improve the mechanical properties of the material and reduce deformation and stability during film blowing and bag making. This ensures that the material will not suffer from severe curling of the film due to the asymmetric structure of PTEG in the outer layer, or unstable film bubbles due to the large temperature difference between the outer layer and other layers during film blowing. At the same time, the roll film will not be significantly deformed and unable to be rolled up during bag making and heat sealing. Low-density polyethylene (LDPE) is added mainly to make the sub-inner layer compatible and connected with the inner layer to avoid delamination. The present invention specifically adds vinyl polymer grafted polyether polyol (POP) to this layer, which, on the one hand, improves the compatibility and plasticizing ability between PE and PP, and on the other hand, greatly improves the overall trouser-type tearing performance of the film.

[0069] The components of the inner layer include metallocene polyethylene (MLLDPE), low-density polyethylene (LDPE), talc masterbatch and erucamide; preferably, in parts by weight, the components of the inner layer include 50-60 parts of metallocene polyethylene, 30-50 parts of low-density polyethylene, 1-5 parts of talc masterbatch and 0.5-1 part of erucamide; preferably, the melt index of the metallocene polyethylene used in the inner layer at 190°C is 1.0-2.0 g / min, and the melt index can specifically be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or a point value between any two of the above; preferably, the haze of the metallocene polyethylene used in the inner layer is less than 20%; preferably, the melt index of the low-density polyethylene used in the inner layer at 190°C is 1.0-2.0 g / min, and the melt index can specifically be 1 .1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 g / min, or any point value between any two of the above; preferably, the haze of the low-density polyethylene used in the inner layer is less than 8%; preferably, the mesh number of the talc powder in the talc masterbatch used in the inner layer is 800-1200 mesh, and the mesh number can specifically be 800, 850, 900, 950, 1000, 1050, 1100 , 1150, 1200 mesh, or any point value between the above two; preferably, the talc content in the talc masterbatch used in the inner layer is 60%-70%, and the talc content can specifically be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, or any point value between the above two; preferably, the thickness of the inner layer accounts for 30% to 35% of the total thickness.

[0070] The inner layer is added with metallocene polyethylene (MLLDPE), which not only improves the overall toughness and heat-sealing strength of the film, but also because the MLLDPE material will become sticky under the shear force of the screw and its plasticizing performance is poorer than that of LDPE. Therefore, after the MLLDPE is mixed with LDPE for film blowing, uneven and uniform fine lines will appear on the surface of the film, which can effectively improve the opening performance of the material and prevent the material from sticking to the film. A small amount of talc powder can not only improve the opening performance of the film, but the low-mesh talc masterbatch selected in the present invention can also effectively increase the roughness of the film surface, prevent the material from sticking to the film, and avoid affecting the heat seal and transparency.

[0071] It is worth noting that the study found that when materials with higher haze are added to the interlayer and inner layer, that is, the sub-outer layer, core layer, sub-inner layer and inner layer, the overall transparency of the film is less, while adding them to the outer layer has a great impact on the transparency of the film. Therefore, in a preferred embodiment of the present invention, the haze of the outer layer component is less than 2% (PETG), the haze of the sub-outer layer component is less than 2% (PETG) and less than 4% (LLDPE), the haze of the core layer component is less than 8% (LDPE), the haze of the sub-inner layer component is less than 10% (PP), less than 8% (LDPE), and less than 5% (POP), and the haze of the inner layer component is less than 20% (MLLDPE) and less than 8% (LDPE).

[0072] The present invention provides a method for manufacturing the heat-shrinkable cushioning packaging air cushion film as described above, comprising the following steps:

[0073] S10, providing an outer layer component, preparing modified pellets of a sub-outer layer, a core layer component, a sub-inner layer component, and an inner layer component;

[0074] In the preparation method provided by the present invention, in step S10, the outer layer component includes polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), and the specific component ratio and parameter indicators are consistent with the outer layer components described above, which will not be repeated here;

[0075] In the preparation method provided by the present invention, in step S10, the secondary outer layer is prepared by modified pellets, and the components of the modified pellets include polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), GMA-modified binder and linear low-density polyethylene (LLDPE). The specific component ratios and parameter indicators are consistent with the secondary outer layer components described above and are not repeated here. The modified pellets are preferably prepared according to the following steps:

[0076] Ethylene terephthalate-1,4-cyclohexanedimethanol (PETG), GMA modified binder and linear low-density polyethylene (LLDPE) are mixed according to a ratio to obtain a modified pelletized mixture, and the mixture is preferably poured into a high-speed mixer according to the ratio and mixed for 3 minutes at a speed of 20 Hz;

[0077] Adding the modified pelletized mixture into an extruder for melt extrusion and pelletization to obtain modified pellets;

[0078] The temperature of each section of the extruder is 150-200°C; more specifically, the temperature of each section of the extruder includes: the temperature of the feeding section is 120°C; the temperature of the first heating section is 150-160°C; the temperature of the second heating section is 180-200°C; the temperature of the third heating section is 180-200°C; the temperature of the compression section is 180-200°C; the temperature of the fourth heating section is 180-200°C; the temperature of the fifth heating section is 180-200°C; the temperature of the extrusion section is 180-200°C; and the temperature of the die head is 180-190°C;

[0079] Preferably, the obtained modified pellets are sent to a stirring oven for baking to remove moisture from polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), and are vacuum-packaged with aluminum foil bags; the temperature of the stirring oven is 80° C. and the baking time is 2 h.

[0080] In the preparation method provided by the present invention, in step S10, the core layer component includes low-density polyethylene (LDPE), and the specific component ratio and parameter indicators are consistent with the core layer components described above, and will not be repeated here;

[0081] In the preparation method provided by the present invention, in step S10, the sub-inner layer components include polypropylene (PP), low-density polyethylene (LDPE) and vinyl polymer grafted polyether polyol (POP). The specific component ratios and parameter indicators are consistent with those of the sub-inner layer components described above and are not repeated here.

[0082] In the preparation method provided by the present invention, in step S10, the inner layer components include metallocene polyethylene (MLLDPE), low-density polyethylene (LDPE), talc masterbatch and erucamide. The specific component ratios and parameter indicators are consistent with the inner layer components described above and are not repeated here.

[0083] S20, using the outer layer component, the modified pellets for preparing the sub-outer layer, the core layer component, the sub-inner layer component and the inner layer component as raw materials, performing multi-layer co-extrusion blown film to form a heat-shrinkable cushioning packaging air cushion film.

[0084] Specifically, the above-mentioned components / pellets of each layer are sequentially added into the hopper of a multi-layer co-extrusion film blowing machine, the inter-layer ratio and processing temperature are set, and the film is blown after being kept warm for 2 hours. The specific temperature settings of each section refer to Table 1.

[0085] Table 1

[0086] Serial number Heating section 1 Heating section 2 Heating section 3 Compression section 4 Heating section 5 die head Outer layer 150-160℃ 220-230℃ 220-230℃ 220-230℃ 220-230℃ 210-220℃ Sub-outer layer 150-160℃ 210-220℃ 210-220℃ 210-220℃ 210-220℃ 210-220℃ core layer 140-150℃ 190-200℃ 190-200℃ 190-200℃ 190-200℃ 210-220℃ Sub-inner layer 140-150℃ 200-210℃ 200-210℃ 200-210℃ 200-210℃ 210-220℃ Inner layer 140-150℃ 200-210℃ 200-210℃ 200-210℃ 200-210℃ 210-220℃

[0087] It should be noted that in order to better plasticize the outer layer of polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG), its temperature needs to reach 220°C or above; in order to avoid the phenomenon that the temperature of other layers of materials is too high during film blowing, resulting in too low die mouth bubble strength and unstable film bubble, the die mouth temperature is set between the processing temperature of polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG) and other materials, so as to avoid delamination and surface water marks caused by excessive temperature difference between the layers of materials.

[0088] S30, bag making;

[0089] The blown film is made into bags, and a special mold is used to heat seal the gourd ball, streamline and other patterns on the surface of the film, and fold it to form an L bag shape. Figure 2 Shown: Add flattened cloth at the bag making and winding position, refer to Figure 3 As shown, the material can remain flat during the winding process.

[0090] Based on the prepared L-bag, the items are placed in the inflated L-bag, placed in a hot air oven at 120-150°C, and baked for 5-10 seconds. The air cushion will shrink during the heating process and eventually completely wrap the entire product without leaving any gaps.

[0091] In order to make the technical solution of the present invention clearer, it is described in detail through the following examples and comparative examples.

[0092] The sources of the raw materials used in the following examples and comparative examples of the present invention are as follows, but are not limited to the following raw materials:

[0093] The model of polyethylene terephthalate-1,4-cyclohexanedimethanol (PETG) is sk k2012 (does not contain bisphenol);

[0094] The model of linear low-density polyethylene (LLDPE) is Exxon 1002ay;

[0095] The model of GMA modified adhesive is Akema;

[0096] The model of low-density polyethylene (LDPE) is Maoming Petrochemical 2426;

[0097] The model of polypropylene (PP) is Nordic 707;

[0098] The model of vinyl polymer grafted polyether polyol (POP) is Dow 1880G;

[0099] The model of metallocene polyethylene (MLLDPE) is Exxon 1018mf.

[0100] In addition, unless otherwise specified, the raw materials used may also be conventional commercial products in this field, or may be prepared by conventional methods in this field.

[0101] Example 1

[0102] In parts by weight, 35 parts of PETG, 10 parts of GMA modified binder and 55 parts of LLDPE were added to a high-speed mixer and mixed at a speed of 20 Hz for 3 minutes to obtain a modified pelletized mixture;

[0103] Add the secondary outer layer mixture into the hopper of the twin-screw extruder, and raise the temperature of the extruder to the set temperature and keep it warm for 2 hours. The specific temperature settings are as follows: the temperature of the feeding section is 120℃, the temperature of the heating section 1 is 150℃, the temperature of the heating section 2 is 180℃, the temperature of the heating section 3 is 180℃, the temperature of the compression section 4 is 180℃, the temperature of the heating section 5 is 180℃, the temperature of the heating section 6 is 180℃, the temperature of the extrusion section is 180℃, and the temperature of the die head is 180℃;

[0104] After extrusion and pelletization, the pellets were sent to a stirring oven at 80°C and baked for 2 hours to remove moisture from the PETG to obtain modified pellets, which were then vacuum-packed in aluminum foil bags.

[0105] S20. The outer layer component, the modified pellets for preparing the sub-outer layer, the core layer component, the sub-inner layer component and the inner layer component are added into the hopper of a multi-layer co-extrusion film blowing machine in sequence, the interlayer ratio and processing temperature are set, and the film is blown after keeping warm for 2 hours. For the specific temperature settings of each section, refer to Table 2.

[0106] Table 2

[0107] Serial number Heating section 1 Heating section 2 Heating section 3 Compression section 4 Heating section 5 die head Outer layer 150 220℃ 220℃ 220℃ 220℃ 210℃ Sub-outer layer 150℃ 210℃ 210℃ 210℃ 210℃ 210℃ core layer 140℃ 190℃ 190℃ 190℃ 190℃ 210℃ Sub-inner layer 140℃ 200℃ 200℃ 200℃ 200℃ 210℃ Inner layer 140℃ 200℃ 200℃ 200℃ 200℃ 210℃

[0108] S30, bag making;

[0109] The blown film is used to make bags, and gourd-shaped, streamlined and other patterns are heat-sealed on the surface of the film using a special mold, and then folded to form an L-bag shape: flattening cloth is added at the bag-making and winding position to keep the material flat during the winding process.

[0110] Comparative Example 1

[0111] The specific implementation of this comparative example is the same as that of Example 1, except that: when film blowing is performed, the processing temperature setting for preparing the modified pellets of the secondary outer layer is as shown in the table below;

[0112] Table 3

[0113] Serial number Heating section 1 Heating section 2 Heating section 3 Compression section 4 Heating section 5 die head Sub-outer layer 150℃ 230℃ 230℃ 230℃ 230℃ 230℃

[0114] The obtained products were subjected to performance comparison tests, see the table below:

[0115] Table 4

[0116]

[0117] Comparative Example 1 shows that when the temperature of the secondary outer layer exceeds 220° C., aging and degradation occur, the film turns yellow, and performance deteriorates.

[0118] Comparative Example 2

[0119] The specific implementation of this comparative example is the same as that of Example 1, except that the three materials of the secondary outer layer, PETG, GMA modified adhesive and LLDPE, are directly added together with the other component materials into the hopper of the co-extrusion upper blown film machine for mixing, heating and film blowing;

[0120] The obtained products were subjected to performance comparison tests, see the table below:

[0121] Table 5

[0122]

[0123]

[0124] The modified granulated components PETG, GMA modified adhesive and LLDPE materials used to prepare the secondary outer layer were not first added to the twin-screw modifier for modification, mixing and granulation. Therefore, they could not be fully plasticized and mixed in the film blowing screw and could not form a film.

[0125] Comparative Example 3

[0126] The specific implementation of this comparative example is the same as that of Example 1, except that: PP material is not added to the components of the secondary inner layer, and LDPE is used instead of PP;

[0127] The obtained products were subjected to performance comparison tests, see the table below:

[0128] Table 6

[0129]

[0130] In this comparative example, since no PP material was added to the secondary inner layer, the film exhibited curling, which was significantly different from Example 1 in which PP material was added, and the mechanical properties and heat shrinkage effects also decreased accordingly.

[0131] Comparative Example 4

[0132] The specific implementation of this comparative example is the same as that of Example 1, except that the material used in the core layer is replaced by LLDPE 1002ay.

[0133] The obtained products were subjected to performance comparison tests, see the table below:

[0134] Table 7

[0135]

[0136] It can be found from the examples and comparative example 4 that when the LDPE of the core layer is replaced with LLDPE, the most obvious feature is that the film blowing stability of LDPE is higher than that of LLDPE, the width fluctuation of the film is smaller, and the heat shrinkage performance is reduced.

[0137] Comparative Example 5

[0138] The specific implementation of this comparative example is the same as that of Example 1, except that: in this comparative example, the PETG material is replaced with MLLDPE model: Exxon 1018mf.

[0139] Comparative Example 6

[0140] The specific implementation of this comparative example is the same as that of Example 1, except that: in this comparative example, the PETG material is replaced with PET model: skbr8040.

[0141] The obtained products were subjected to performance comparison tests, see the table below:

[0142] Table 8

[0143]

[0144] It can be found from Example 1 and Comparative Example 5 that the addition of PETG can significantly improve the barrier properties of the film, making the film have better gas retention performance; not only that, the surface heat resistance is simultaneously improved by 70°C; and the material has heat shrinkage properties.

[0145] Comparative Example 7

[0146] The specific implementation of this comparative example is the same as that of comparative example 6, except that the temperature of the outer layer and the sub-outer layer is increased to 250° C., as shown in the table below;

[0147] Table 9

[0148]

[0149] The obtained products were subjected to performance comparison tests, see the table below:

[0150] Table 10

[0151]

[0152] From Example 1 and Comparative Example 6, it can be seen that PET cannot replace PETG because it cannot be molded after replacement. A comparison of Example 1 and Comparative Example 7 shows that when the processing temperature is increased to 250°C, although PET is plasticized, the film still cannot be formed. The main reason is that the temperature difference between the outer layer and sub-outer layer and the core layer, sub-inner layer, and inner layer is too large, and the materials in the core layer, sub-inner layer, and inner layer cannot withstand such high temperatures.

[0153] Comparative Example 8

[0154] The specific implementation of this comparative example is the same as that of Example 1, except that the PETG sk k2012 used in the outer layer is replaced with Dawn PETG modified material cr-501 with a haze of 23%.

[0155] Comparative Example 9

[0156] The specific implementation of this comparative example is the same as that of Example 1, except that: the PETG skk2012 used in the secondary outer layer is replaced with Dawn PETG modified material cr-501 with a haze of 23%; and the LLDPE with a haze of 3.3% is replaced with 7042 with a haze of 10%.

[0157] Comparative Example 10

[0158] The specific implementation of this comparative example is the same as that of Example 1, except that the LDPE 2426 with a haze of 7% used in the core layer is replaced with LLDPE 2230 with a haze of 70%.

[0159] Comparative Example 11

[0160] The specific implementation of this comparative example is the same as that of Example 1, except that the LDPE 2426 with a haze of 7% used in the secondary inner layer is replaced with LLDPE 2230 with a haze of 70%.

[0161] Comparative Example 12

[0162] The specific implementation of this comparative example is the same as that of Example 1, except that the MLLDPE with a haze of 18% used in the inner layer is replaced with LLDPE 2230 with a haze of 70%.

[0163] The products obtained in Comparative Examples 8-12 were subjected to performance comparison tests, as shown in the table below:

[0164] Table 11

[0165]

[0166]

[0167] As can be seen from Example 1 and Comparative Example 8, replacing the outer layer's PETG with a high-haze PETG significantly reduced the film's haze. Comparisons between Example 1 and Comparative Examples 9, 10, 11, and 12 reveal that replacing the outer layer's PETG with a higher-haze material has minimal impact on the overall film's haze.

[0168] Example 2

[0169] In parts by weight, 50 parts of PETG, 20 parts of GMA modified adhesive and 30 parts of LLDPE were added to a high-speed mixer and mixed at a speed of 20 Hz for 3 minutes to obtain a modified pelletized mixture;

[0170] The secondary outer layer mixture is added to the hopper of the twin-screw extruder, and the temperature of the extruder is raised to the set temperature and kept warm for 2 hours. The specific temperature settings are as follows: the temperature of the feeding section is 120°C, the temperature of the heating section 1 is 160°C, the temperature of the heating section 2 is 200°C, the temperature of the heating section 3 is 200°C, the temperature of the compression section 4 is 200°C, the temperature of the heating section 5 is 200°C, the temperature of the heating section 6 is 200°C, the temperature of the extrusion section is 200°C, and the temperature of the die head is 190°C;

[0171] After extrusion and pelletization, the pellets were sent to a stirring oven at 80°C and baked for 2 hours to obtain modified pellets, which were then vacuum-packed in aluminum foil bags.

[0172] S20, using the outer layer component, the modified pellets for preparing the sub-outer layer, the core layer component, the sub-inner layer component, and the inner layer component as raw materials, sequentially adding them into the hopper of a multi-layer co-extrusion blown film machine, setting the interlayer ratio and processing temperature, and maintaining the temperature for 2 hours for film blowing. Specific temperature settings for each section are shown in Table 12;

[0173] Table 12

[0174]

[0175]

[0176] S30, bag making;

[0177] The blown film is used to make bags, and gourd-shaped, streamlined and other patterns are heat-sealed on the surface of the film using a special mold, and then folded to form an L-bag shape: flattening cloth is added at the bag-making and winding position to keep the material flat during the winding process.

[0178] The obtained products were subjected to performance comparison tests, see the table below:

[0179] Table 13

[0180]

[0181] It can be found from Example 1 and Example 2 that within the specified temperature range and material range, the test results of the examples all meet the use requirements.

[0182] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention may be improved in only one or several aspects, without having to simultaneously solve all the technical problems listed in the prior art or background art. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as limiting the claim.

[0183] Although terms such as outer layer, sub-outer layer, core layer, sub-inner layer, and inner layer are frequently used herein, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitations is contrary to the spirit of the present invention; the terms "first," "second," and the like (if any) in the description and claims of the embodiments of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0184] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat-shrinkable cushioning packaging air cushion film, characterized in that: The film is co-extruded by at least five layers, and the five layers include, from the outside to the inside, an outer layer, a sub-outer layer, a core layer, a sub-inner layer and an inner layer; The components of the outer layer include polyethylene terephthalate-1,4-cyclohexanedimethanol ester; The secondary outer layer is made of modified pellets, and the components of the modified pellets include polyethylene terephthalate-1,4-cyclohexanedimethanol ester, GMA modified binder and linear low-density polyethylene; The core layer comprises low-density polyethylene; The method for preparing the film comprises the following steps: Providing outer layer components, modified pellets for preparing a sub-outer layer, core layer components, sub-inner layer components, and inner layer components; Using the outer layer component, modified pellets, core layer component, sub-inner layer component and inner layer component as raw materials, multi-layer co-extrusion blown film is carried out to form a heat-shrinkable cushioning packaging air cushion film; The modified pellets are prepared according to the following steps: Ethylene terephthalate-1,4-cyclohexanedimethanol ester, GMA modified binder and linear low-density polyethylene are mixed according to a proportion to obtain a modified pelletized mixture; Adding the modified pelletized mixture into an extruder for melt extrusion and pelletization to obtain modified pellets; During film blowing, the temperatures of the five heating sections of the outer layer are 150-160°C, 220-230°C, 220-230°C, 220-230°C, and 220-230°C, and the die head temperature is 210-220°C; the temperatures of the five heating sections of the secondary outer layer are 150-160°C, 210-220°C, 210-220°C, 210-220°C, and 210-220°C, and the die head temperature is 210-220°C; the temperatures of the five heating sections of the core layer are 140-150°C, 190-200°C, 1 90-200°C, 190-200°C, 190-200°C, and the die temperature is 210-220°C; the temperatures of the five heating sections of the secondary inner layer are 140-150°C, 200-210°C, 200-210°C, 200-210°C, and 200-210°C, and the die temperature is 210-220°C; the temperatures of the five heating sections of the inner layer are 140-150°C, 200-210°C, 200-210°C, 200-210°C, and 200-210°C, and the die temperature is 210-220°C; The haze of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer is less than 2%; The components of the secondary inner layer include polypropylene, low-density polyethylene and vinyl polymer grafted polyether polyol.

2. The heat-shrinkable cushioning packaging air cushion film according to claim 1, characterized in that: The polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer has a heat distortion temperature (HDT) of 65° C. or higher and 75° C. or lower, as measured at 0.45 MPa according to ASTM D648; and / or The specific gravity of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the outer layer is 1.25-1.28 g / cm 3 .

3. The heat-shrinkable cushioning packaging air cushion film according to claim 1, characterized in that: The modified pelletized material comprises, by weight, 35-50 parts of polyethylene terephthalate-1,4-cyclohexanedimethanol, 10-20 parts of a GMA modified binder, and 35-55 parts of a linear low-density polyethylene; and / or The specific gravity of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer is 1.25-1.28 g / cm 3 and / or The haze of polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer is less than 2%; and / or The polyethylene terephthalate-1,4-cyclohexanedimethanol used in the secondary outer layer has a heat distortion temperature (HDT) of less than 75° C. as measured at 0.45 MPa according to ASTM D648; and / or The linear low-density polyethylene used in the secondary outer layer has a melt index of 1.0-2.0 g / min at 190°C.

4. The heat-shrinkable cushioning packaging air cushion film according to claim 1, characterized in that: The low-density polyethylene used in the core layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or The haze of the low-density polyethylene used in the core layer is less than 8%.

5. The heat-shrinkable cushioning packaging air cushion film according to claim 1, characterized in that: In parts by weight, the components of the secondary inner layer include 35-50 parts of polypropylene, 35-50 parts of low-density polyethylene and 10-20 parts of vinyl polymer grafted polyether polyol; and / or The polypropylene used in the secondary inner layer has a melt index of 1.0-2.0 g / min at 190°C; and / or The haze of the polypropylene used in the secondary inner layer is less than 10%; and / or The low-density polyethylene used in the secondary inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or The haze of the low-density polyethylene used in the secondary inner layer is less than 8%; and / or The vinyl polymer grafted polyether polyol used in the secondary inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or The haze of the vinyl polymer grafted polyether polyol used in the secondary inner layer is less than 5%.

6. The heat-shrinkable cushioning packaging air cushion film according to claim 1, characterized in that: The components of the inner layer include metallocene polyethylene, low-density polyethylene, talc masterbatch and erucamide.

7. The heat-shrinkable cushioning packaging air cushion film according to claim 6, characterized in that: In parts by weight, the components of the inner layer include 50-60 parts of metallocene polyethylene, 30-50 parts of low-density polyethylene, 1-5 parts of talc masterbatch and 0.5-1 part of erucamide; The metallocene polyethylene used in the inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or The haze of the metallocene polyethylene used in the inner layer is less than 20%; and / or The low-density polyethylene used in the inner layer has a melt index of 1.0-2.0 g / min at 190° C.; and / or The haze of the low-density polyethylene used in the inner layer is less than 8%; and / or The mesh size of the talc powder in the talc powder masterbatch used in the inner layer is 800-1200 mesh; and / or The content of talc powder in the talc powder masterbatch used in the inner layer is 60%-70%.

8. The heat-shrinkable cushioning packaging air cushion film according to claim 1, characterized in that: The thickness of the outer layer accounts for 30% to 35% of the total thickness; and / or The thickness of the secondary outer layer accounts for 10% to 15% of the total thickness; and / or The thickness of the core layer accounts for 10% to 15% of the total thickness; and / or The thickness of the sub-inner layer accounts for 10% to 15% of the total thickness; and / or The thickness of the inner layer accounts for 30% to 35% of the total thickness.

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