Barrier bag

Abstract

The application discloses a single-material barrier bag, which comprises a plurality of functional films arranged in a thickness direction, at least one of the functional films comprises a plurality of sub-functional films, the plurality of sub-functional films are combined into one by a plurality of co-extrusion, the plurality of films have oriented lamellar structures by longitudinal stretching, and a polyethylene weight ratio of the barrier bag is greater than or equal to 90%.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic flexible packaging, in particular to a barrier bag. Background Art

[0002] Traditional aluminum-containing packaging bags often utilize aluminum foil and aluminized layers for oxygen and moisture resistance. The aluminized layer is a 300-400 angstrom thick layer of aluminum vapor-deposited onto the surface of a plastic film. However, a high aluminum content hinders the separation and recycling of packaging materials, making aluminum reduction crucial for packaging bags. Currently, the barrier ingredients added to reduce aluminum content often contain chlorine, which is environmentally harmful and toxic, and therefore does not meet environmental standards. Furthermore, aluminized substrates primarily include polyester film (PET), cast polypropylene film (CPP), and biaxially oriented polypropylene film (BOPP). Polyethylene film (PE) exhibits poor adhesion to aluminum plating, resulting in poor durability after lamination, making it unsuitable for direct aluminization.

[0003] Furthermore, the printed films on packaging bags are commonly made of PET and oriented polypropylene (OPP) films, which differ from the remaining PE materials in the bag, making them less suitable for recycling. Furthermore, bags made from a single PE material are generally softer and fall short of the desired appearance, texture, and strength. Furthermore, packaging bags must tear easily when opened, preventing leakage of contents, while standard polyethylene films exhibit poor linear tear resistance.

[0004] Therefore, developing a single-material barrier bag with low aluminum content, high barrier, high light-shielding, high temperature resistance, high printing accuracy, texture, easy to tear horizontally, and recyclable is an urgent problem to be solved in this field. Summary of the Invention

[0005] The present invention aims to solve one of the technical problems in the related art to a certain extent. To this end, the present invention provides a barrier bag.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a barrier bag, comprising a multi-layer functional film stacked along the thickness direction, at least one layer of the functional film comprises a multi-layer sub-functional film, the multi-layer sub-functional film is combined into one by multi-layer co-extrusion, the multi-layer sub-functional film has an oriented lamellar structure by longitudinal stretching, and the polyethylene weight ratio of the barrier bag is greater than or equal to 90%.

[0007] Furthermore, the components of the sub-functional membrane include polyethylene and its copolymers having at least one molecular chain length with at least one degree of branching.

[0008] Furthermore, the components of the sub-functional film include at least one of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, metallocene polyethylene, ethylene-vinyl alcohol polymer, and cycloolefin copolymer.

[0009] Furthermore, the number of layers of the sub-functional films of the functional film is an odd number, and the number of layers of the sub-functional films of the functional film does not exceed 11 layers.

[0010] Furthermore, the multilayer functional film includes a first barrier film, a second aluminized film and a third heat-sealing film, the first barrier film is located in the outermost layer, the heat-sealing film is located in the innermost layer, the aluminized film also includes an aluminized layer, and the aluminized layer is arranged on the outermost side of the aluminized film and is respectively bonded to the innermost sub-functional film of the first barrier film and the sub-functional film of the aluminized film.

[0011] Further, the first barrier film includes nine layers of the sub-functional films; the components of the fifth sub-functional film of the first barrier film include ethylene-vinyl alcohol polymer, the components of the fourth and sixth sub-functional films of the first barrier film are the same and include polyolefin adhesive resin, the components of the first layer and the eighth sub-functional film of the first barrier film are the same and include linear low-density polyethylene, the components of the second, third and seventh sub-functional films of the first barrier film are the same and include low-density polyethylene and metallocene polyethylene, and the mass ratio of the low-density polyethylene to the metallocene polyethylene is between 4:1 and 9:1, and the components of the ninth sub-functional film of the first barrier film include low-density polyethylene and linear low-density polyethylene, and the mass ratio of the low-density polyethylene to the linear low-density polyethylene is between 2:3 and 1:1.

[0012] Furthermore, the thickness of the first barrier film is between 15um and 35um.

[0013] Furthermore, the first barrier film includes: nine layers of the sub-functional films; the components of the second to seventh sub-functional films of the first barrier film all include low-density polyethylene and metallocene polyethylene in a mass ratio between 4:1 and 9:1, the components of the first sub-functional film and the eighth sub-functional film of the first barrier film are the same and include linear low-density polyethylene, and the components of the ninth sub-functional film of the first barrier film include low-density polyethylene and linear low-density polyethylene and the mass ratio of the low-density polyethylene and the linear low-density polyethylene is between 2:3 and 1:1.

[0014] Furthermore, the aluminized film includes: nine layers of the sub-functional film and the aluminized layer; the first layer of the sub-functional film to the ninth layer of the aluminized film have the same components and include high-density polyethylene, the thickness of the aluminized film is between 25um and 70um, and the thickness of the aluminized layer is between 2.9 angstroms and 3.5 angstroms.

[0015] Furthermore, the heat-sealing film includes: nine layers of the sub-functional films; the components of the first to eighth layers of the heat-sealing film include linear low-density polyethylene and cyclic olefin copolymer, and the mass ratio of the low-density polyethylene to the cyclic olefin copolymer is between 7:3 and 9:1; the components of the ninth layer of the heat-sealing film include low-density polyethylene and linear low-density polyethylene, and the mass ratio of the low-density polyethylene to the linear low-density polyethylene is between 4:1 and 9:1; the thickness of the heat-sealing film is between 30um and 60um.

[0016] The barrier bag of the present invention has the following beneficial effects:

[0017] The barrier bag of the present invention has a multi-layer functional film, which includes a multi-layer sub-functional film. Compared with the barrier bag with an ordinary single-layer functional film, the setting of the multi-layer sub-functional film provides more layers, and each layer of sub-functional film can have different properties. The multi-layer sub-functional film is co-extruded to obtain a functional film, which enhances the different properties of the functional film, so that the functional film has better comprehensive performance (higher barrier properties, higher mechanical properties such as strength, stiffness and toughness, better gloss, higher temperature resistance, etc.), broadens the scope of application projects of the barrier bag, and solves challenging industrial problems. The components of the multi-layer sub-functional film can also be the same, thereby improving the compatibility between the functional film layers.

[0018] In addition, each layer of sub-functional film has an oriented lamellar structure through longitudinal stretching, and the functional film composed also has a higher orientation, further improving the overall strength, stiffness, glossiness, barrier properties and heat resistance of the barrier bag.

[0019] On the other hand, the components of each functional film layer of the barrier bag of the present invention include polyethylene, with the polyethylene weight ratio exceeding 90%. It is a barrier bag made of a single material and can therefore be recycled and reused at a lower cost and higher efficiency.

[0020] In summary, the barrier bag of the present invention adopts the above-mentioned components and structure to replace aluminum foil and conventional thickness aluminum-plated layers to play the role of oxygen and moisture barrier, reduce the thickness of the aluminum-plated layer, greatly reduce the aluminum content, and is more conducive to recycling. In addition, various performances are further improved, and the bag has high barrier properties, high strength, high stiffness, high gloss, high temperature resistance and the like.

[0021] These features and advantages of the present invention will be further disclosed in the following detailed description and accompanying drawings. The preferred embodiments and means of the present invention will be fully illustrated in conjunction with the accompanying drawings, but are not intended to limit the technical solutions of the present invention. Furthermore, although multiple features, elements, and components may be present in each of the following text and accompanying drawings, they may be labeled with different symbols or numbers for convenience, but all represent components with the same or similar structure or function. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings:

[0023] Figure 1 This is a schematic structural diagram of an embodiment of a barrier bag provided by the present invention;

[0024] Figure 2 This is a schematic structural diagram of an embodiment of the first barrier film provided by the present invention;

[0025] Figure 3 This is a schematic structural diagram of an embodiment of the aluminum-plated film provided by the present invention;

[0026] Figure 4 This is a schematic structural diagram of an embodiment of the heat-sealing film provided by the present invention;

[0027] Figure 5 is a schematic structural diagram of another embodiment of the first barrier film provided by the present invention;

[0028] Figure 6 A schematic structural diagram of another embodiment of a barrier bag provided by the present invention;

[0029] Figure 7 This is a flow chart of an implementation method of the barrier bag manufacturing method provided by the present invention.

[0030] Description of Reference Numerals

[0031] 1: Barrier bag 11: First barrier film

[0032] 12: Aluminum film 13: Heat sealing film

[0033] 110: EVOH barrier layer 111: outer barrier layer

[0034] 112: First composite layer 113: Secondary barrier layer

[0035] 114: Adhesive layer

[0036] 120: Aluminum coating 121: Aluminum substrate

[0037] 130: easy-tear heat seal layer 131: first easy-tear layer DETAILED DESCRIPTION

[0038] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described in the embodiments are intended to explain the present invention and are not to be construed as limiting the present invention.

[0039] Reference in this specification to "one embodiment" or "an embodiment" or "example" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0040] It should be noted that in the present application, "inner side" refers to the side of the packaging bag close to the packaged articles, and "outer side" refers to the side away from the packaged articles.

[0041] According to the Circular Economy Design Guide of the European Flexible Packaging Circularity Consortium (CEFLEX), the single material of the flexible packaging mainly refers to a single polyolefin material, such as a single polypropylene (PP) or a single polyethylene (PE) material, and the weight ratio of the single material is more than 90%, and other barrier components such as silicon oxide, aluminum oxide, aluminum plating, and ethylene-vinyl alcohol polymer are allowed to contain at most 5% by weight.

[0042] The present application provides a barrier bag, comprising a plurality of functional films stacked in the thickness direction, at least one of the functional films comprising a plurality of sub-functional films, the plurality of sub-functional films being combined into one by multi-layer co-extrusion, the plurality of sub-functional films having oriented lamellar structures by longitudinal stretching, and the weight ratio of polyethylene of the barrier bag being greater than or equal to 90%.

[0043] Compared with the barrier bag of the ordinary single-layer functional film, the plurality of sub-functional films provides more layers, each sub-functional film has different properties, the plurality of sub-functional films are combined into one functional film by multi-layer co-extrusion, thereby enhancing the different properties of the functional film, so that the functional film has better comprehensive performance (higher barrier property, higher mechanical properties such as strength, stiffness and toughness, better gloss, higher temperature resistance, etc.), which widens the application engineering range of the barrier bag, solves challenging industrial problems, and the properties of the plurality of sub-functional films can also be the same, thereby improving the overall compatibility of the functional film and enhancing a certain specific function of the barrier bag.

[0044] The components of the plurality of sub-functional films include polyethylene and its copolymers having a plurality of molecular chains of different lengths and a plurality of branching degrees, and as a preferred, the components of the sub-functional film include at least one of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, metallocene polyethylene, ethylene-vinyl alcohol polymer, and cyclic olefin copolymer.

[0045] In addition, each sub-functional film has oriented lamellar structures by longitudinal stretching, and the functional film composed of the sub-functional films also has higher orientation, which further improves the overall strength, stiffness, gloss, barrier property, and heat resistance of the barrier bag. The components of each functional film of the barrier bag of the present application include polyethylene, and the weight ratio of polyethylene is more than 90%, which is a barrier bag with a single material, and therefore can be recycled and reused at a lower cost and higher efficiency.

[0046] The barrier bag adopting the structure and components of the application can replace the aluminum foil or the aluminized layer in the prior art to play the role of oxygen and moisture resistance, greatly reduces the aluminum content, is more conducive to recycling, and further improves various performances, and has high barrier property, high strength, high stiffness, high gloss, high temperature resistance and other performances.

[0047] The number of layers of the sub-functional film is not specially limited in the application, only needs to satisfy that the number of layers of the sub-functional film of the functional film is odd, and the number of layers of the sub-functional film of the functional film does not exceed 11, and as a preferred, the functional film of the application can be one of one-layer sub-functional film, three-layer sub-functional film, five-layer sub-functional film, seven-layer sub-functional film, nine-layer sub-functional film and eleven-layer sub-functional film or a combination of one or more thereof.

[0048] In some embodiments, the barrier bag is three-layer functional films stacked from outside to inside, wherein the outer layer functional film comprises five-layer co-extruded sub-functional films, the middle layer functional film comprises one layer of functional film prepared by casting, and the inner layer functional film comprises seven-layer co-extruded sub-functional films, and the functional films all have oriented lamellar structures by longitudinal stretching.

[0049] In some embodiments, the barrier bag is two-layer functional films stacked from outside to inside, wherein the outer layer functional film comprises three-layer co-extruded sub-functional films, and the inner layer functional film comprises nine-layer co-extruded sub-functional films, and the functional films all have oriented lamellar structures by longitudinal stretching.

[0050] In some embodiments, the barrier bag is three-layer functional films stacked from outside to inside, wherein the outer layer functional film comprises nine-layer co-extruded sub-functional films, the middle layer functional film comprises nine-layer co-extruded sub-functional films, and the inner layer functional film comprises nine-layer co-extruded sub-functional films, and the three-layer functional films all have oriented lamellar structures by longitudinal stretching.

[0051] In some embodiments, the multilayer sub-functional film in the functional film also has multiple thicknesses. For high-barrier multilayer co-extruded composite films, the film thickness and uniformity have a significant impact on the film quality. The thickness of the produced sub-functional film depends on the extrusion amount, the pulling speed, and the film width. The thickness of the sub-functional film is controlled by controlling the corresponding component extrusion amount, the pulling speed, and the width of the film. The present invention does not specifically limit the thickness of the multilayer sub-functional film, and it only needs to be within the thickness range of the conventional co-extruded film. The thickness can represent the degree of enhanced performance. For example, in order to improve the strength of the barrier bag, in the film after nine layers of co-extrusion and longitudinal stretching, a high-strength polyethylene component is added to the extruder during the preparation stage, its content is increased, and the same high-strength polyethylene component is added to the adjacent extruder. The above method can increase the thickness of the sub-functional film with high-strength function, so that the sub-functional film with greater thickness and high strength can improve the overall strength of the film to a greater extent. In order to improve other properties, the thickness of the corresponding sub-functional film can also be increased.

[0052] In some embodiments, as Figure 1 As shown, the multi-layer functional film of the barrier bag 1 includes a first barrier film 11, an aluminized film 12 and a heat-sealing film 13. The first barrier film 11 is located in the outermost layer, the heat-sealing film 13 is located in the innermost layer, and the aluminized film 12 also includes an aluminized layer 120. The aluminized layer 120 is arranged on the outermost side of the aluminized film 12 and is respectively bonded to the sub-functional film of the first barrier film and the sub-functional film of the aluminized film. The outermost surface of the heat-sealing film 13 is bonded to the innermost surface of the aluminized film 12.

[0053] In the present invention, the addition of an aluminized layer 120 imparts excellent barrier properties to the barrier bag against light, oxygen, and water vapor. The aluminized layer comprises aluminum. However, the composition and structure of the barrier bag of the present invention already provide high barrier properties, making it a suitable alternative to conventional aluminized layers in the art. Therefore, the thickness of the aluminized layer provided in the present invention can be significantly less than conventional aluminized layers in the art. As an optional embodiment, the thickness of the aluminized layer provided in the present invention is between 2.9 angstroms and 3.5 angstroms.

[0054] In some embodiments, the sub-functional film of the aluminum-plated film is also called an aluminum-plated substrate, such as Figure 3As shown, the present invention does not impose any special restrictions on the aluminum-plated substrate 121 of the aluminum-plated film 12. It only needs to be a single material of polyethylene and be able to fit with the aluminum-plated layer 120 and meet the standards specified in the application. The aluminum-plated layer 120 is arranged on the outermost surface of the aluminum-plated substrate 121. Therefore, the outermost surface of the aluminum-plated substrate 121 requires a higher aluminum adhesion. The higher aluminum adhesion requires that the aluminum-plated substrate 121 needs to be high-strength, hard and not easy to deform, so that the aluminum-plated layer 120 is more completely plated on the surface of the aluminum-plated substrate 121 during vacuum aluminum plating and is not easy to fall off. This requires that the aluminum-plated substrate 121 of the aluminum-plated film needs a certain stiffness to meet the overall strength and hardness of the aluminum-plated film 12.

[0055] Preferably, the components of the aluminum-plated substrate 121 of the aluminum-plated film 12 include high-density polyethylene (HDPE). HDPE has the characteristics of low branching, and the molecular chains as branches are very short. At the same time, the molecular structure is tightly arranged, and the degree of crystallization is higher than 90%, so that the sub-functional film prepared by co-extrusion and longitudinal stretching of the components has good stiffness and water vapor barrier properties. The stiff film surface is more conducive to aluminum plating. Furthermore, the surface of the aluminum-plated substrate 121 formed by multi-layer HDPE co-extrusion blow molding and longitudinal stretching can be corona treated to increase the surface roughness, so that the aluminum-plated layer 120 can be well attached to the surface of the aluminum-plated substrate 121 during subsequent aluminum plating, thereby increasing the adhesion of the aluminum plating on the surface of the aluminum-plated substrate 121, making the aluminum-plated layer 120 more firmly bonded to the aluminum-plated substrate 121, and compensating for the shortcoming of weak bonding force of PE film aluminum plating causing decreased barrier properties.

[0056] The innermost sub-functional film of the first barrier film is bonded to the aluminum coating layer. Preferably, the two films are bonded together using an adhesive. Furthermore, in order to increase the composite strength between the two films, Figure 1 and Figure 2 As shown, the surface of the first composite layer 112 of the first barrier film may be subjected to corona treatment to increase the surface roughness, thereby improving the adhesion of the first composite layer 112 to the aluminum plating layer 120 and facilitating printing processing.

[0057] The present invention imposes no specific restrictions on the composition of the first barrier film; it only needs to be a single polyethylene material, adhere to the surface of the aluminum coating, and meet the specified application standards. Preferably, the first barrier film comprises low-density polyethylene (LDPE), metallocene polyethylene (MPE), and linear low-density polyethylene (LLDPE).

[0058] In some embodiments, the sub-functional film of the first barrier film can also be used as a printing layer for printing patterns. The present invention does not impose special restrictions on the specific position of the printing layer. It only needs to meet the requirements of being able to print patterns and the printed patterns meeting the application requirements. Preferably, the innermost sub-functional film of the first barrier film is used for printing patterns. The present invention does not impose special restrictions on the components of the printing layer. Preferably, the components of the printing layer include at least one of low-density polyethylene, metallocene polyethylene and linear low-density polyethylene.

[0059] Traditional PE films are prone to stretching and deformation during high-speed printing, resulting in poor printing results and low precision. This elongation requires reducing printing speeds by at least 30% to 40%. However, the first barrier film of the present invention, formed by coextruding multiple sub-functional films and then longitudinally orienting them (MDO), offers high strength, stiffness, resistance to deformation, and high-temperature resistance. The structure and composition of the printing layer within the first barrier film provide the film with the rigidity to withstand elongation during high-speed printing. This ensures excellent printing results without reducing printing speeds, thereby improving printing efficiency.

[0060] Furthermore, the LLDPE component added to the first barrier film has a linear backbone with short, evenly branched chains. These short branches are able to slide against each other during elongation. Therefore, the film obtained by co-extrusion and longitudinal stretching of the LLDPE components is highly flexible and has excellent thermal and dimensional stability. During the printing process, it exhibits high impact strength and rigidity, preventing excessive elongation and deformation of the film during printing, thereby achieving better printing precision and quality. The high rigidity also provides a certain degree of hardness to the barrier bag. Furthermore, the film exhibits excellent chemical resistance over a wide temperature range, allowing for printing with inks of various compositions. Its heat resistance, melting point, and softening point are all among the best among plastic films, making the film surface more resistant to high temperatures and non-sticky to hot knives. Furthermore, the film exhibits high ink adhesion, achieving ideal printing results. The printing process is preferably, but not limited to, gravure, flexographic, and offset printing.

[0061] Low-density polyethylene (LDPE) contains numerous short and long chain branches. Coextrusion and longitudinal stretching of LDPE components yields films with reduced hardness and strength, but excellent plasticity. As a sub-functional film, this provides enhanced plasticity for the overall functional film. Its high transparency also contributes to a higher gloss, lower melting point, and improved fluidity, resulting in lower heat-seal temperatures and seal bond strengths than other PE materials. Compared to traditional polyethylene, metallocene polyethylene (MPE) has a higher molecular weight and a denser distribution, resulting in greater impact strength and elongation at break. However, MPE also exhibits excellent transparency and low haze.

[0062] The first barrier film having the above components is longitudinally stretched after multi-layer co-extrusion, and has higher gloss and transparency, making it more beautiful. In addition, after longitudinal stretching, the tensile strength of the first barrier film in the transverse and longitudinal directions is greatly improved, thereby increasing the overall strength of the barrier bag, while also having certain barrier properties.

[0063] In other embodiments, the first barrier film also comprises ethylene vinyl alcohol (EVOH). The addition of EVOH further enhances the film's oxygen and moisture barrier properties. Films co-extruded and longitudinally stretched from the EVOH component significantly improve the barrier bag's overall oxygen and moisture barrier properties, replacing the thicker aluminum coatings typically used in the art. This further reduces the aluminum content of the barrier bag, allowing for a thinner aluminum coating, reducing aluminum content and facilitating its separation and recycling. Furthermore, EVOH is environmentally friendly and contributes to the development of a circular economy. In some embodiments, the aluminum coating has a thickness between 2.9 and 3.5 angstroms, significantly reducing the thickness of the aluminum coating compared to conventional aluminum coatings, which typically range from 300 to 400 angstroms.

[0064] like Figure 1 and Figure 2 As shown, the present invention does not impose any particular restrictions on the placement of the EVOH barrier layer 110, as long as it can perform a barrier function, adheres to other sub-functional films, and does not cause the first barrier film to curl. As an optional embodiment, in order to improve the bonding between the EVOH barrier layer 110 and other sub-functional films and prevent curling of the first barrier film, the EVOH barrier layer 110 is positioned in the middle of the first barrier film 11 and connected to the adjacent secondary barrier layers 113 on both sides via adhesive layers 114. Preferably, the adhesive layers 114 are selected from polyethylene adhesive resins, and the EVOH barrier layer 110 is used as the middle layer. The adhesive layers 114 on the adjacent two sides are symmetrically structured with the same components, the same proportions, and the same thickness, and are symmetrically positioned. The secondary barrier layers 113 on the adjacent two sides are also structured with the same components, the same proportions, and the same thickness. The outer barrier layers 111 on the adjacent two sides are also structured with the same components, the same proportions, and the same thickness. This ensures that the forces on both sides of the EVOH barrier layer are equal, and the curling problem of the first barrier film is solved.

[0065] The present invention imposes no specific restrictions on the composition of the heat-sealing film. It only needs to be a single polyethylene material, exhibit a certain heat-sealing effect and transverse tear resistance, and meet the application standards. Preferably, the heat-sealing film comprises linear low-density polyethylene (LLDPE), cyclic olefins, and low-density polyethylene (LDPE).

[0066] It is difficult to tear polyethylene packaging bags into straight lines, that is, the tear orientation is poor, such as Figure 1 and Figure 4As shown, the present invention produces a first tearable layer 131 by coextruding and longitudinally stretching LLDPE and cycloolefin components. This longitudinal stretching imparts significant longitudinal orientation to the structure of the first tearable layer 131. When the multi-layer functional film is composited to form a barrier bag, the bag is produced horizontally, with the tear direction aligned with the film material, both being longitudinal. This allows the bag to be easily torn in the shear direction, with the tearing action acting as a tearing notch. Furthermore, LLDPE has a short, evenly branched linear main chain, eliminating significant tensile resistance due to complex transverse branching, thereby achieving transverse tearability. The addition of a tearable cycloolefin component to the coextruded, longitudinally stretched base film of the first tearable layer 131 introduces a tear failure point into the first tearable layer 131. Under external force, the tear failure point tears first, then drives other non-tearable areas, further extending the tearing action to the entire barrier bag, imparting transverse tearability and enhancing ease of use.

[0067] The heat-sealable film also includes an easy-tear heat-sealable layer 130. The easy-tear heat-sealable layer 130 is preferably, but not limited to, LDPE. LDPE has a low melting point, resulting in a low melting point and heat-sealing temperature for the barrier bag of the present invention. During the heat-sealing process, the easy-tear heat-sealable layer 130 preferentially melts to form a fluid and viscous melt. This melt is then pressed together with the easy-tear heat-sealable layer 130 of the adjacent barrier bag to form a sealed barrier bag. The easy-tear heat-sealable layer 130 may also include LLDPE.

[0068] The present invention does not impose any particular restrictions on the placement of the first easy-tear layer 131 and the easy-tear heat-seal layer 130. The easy-tear heat-seal layer 130 only needs to be located on the outside of the heat-seal film 13 and heat-sealed to the easy-tear heat-seal layer 130 of another heat-seal film 13. Preferably, the easy-tear heat-seal layer 130 is located on the innermost side of the heat-seal film 13, and the first easy-tear layer 131 is located on the outside of the heat-seal film 13 and in contact with the aluminized film 12.

[0069] The heat-sealing film of the present invention also has the advantages of excellent environmental stress crack resistance, low sealing temperature, high heat-sealing strength and high stiffness.

[0070] The present invention does not impose any particular restrictions on the number of sub-functional film layers included in the functional film, as long as they meet the corresponding functions. Preferably, the first barrier film, the aluminized film, and the heat-sealing film each include nine sub-functional film layers, with the nine sub-functional film layers including the first to ninth layers stacked from the outside inward.

[0071] The present invention does not impose any special restrictions on the number of layers and composition ratio of the first barrier film. Preferably, Figure 2 As shown, the first barrier film includes nine layers of sub-functional films. Specifically, the first barrier film includes: a first layer; a second layer; a third layer; a fourth layer; a fifth layer; a sixth layer; a seventh layer; an eighth layer; a ninth layer;

[0072] The fifth layer is an EVOH barrier layer 110, the components of which include ethylene-vinyl alcohol polymer. Preferably, the fifth layer includes 100 wt% of ethylene-vinyl alcohol polymer.

[0073] The fourth and sixth layers are adhesive layers 114, which have the same composition and include polyolefin adhesive resin. The adhesive layer 114 is used to bond the EVOH barrier layer 110 to the adjacent sub-functional film, thereby improving the bonding strength and preventing the film from curling due to poor interlayer compatibility.

[0074] The first layer and the eighth layer are outer barrier layers 111, which have the same composition and include linear low-density polyethylene, preferably 100 wt% linear low-density polyethylene;

[0075] The second, third and seventh layers are secondary barrier layers 113, which have the same composition and include low-density polyethylene and metallocene polyethylene, and the mass ratio of LDPE to MPE is between 4:1 and 9:1;

[0076] The ninth layer is the first composite layer 112 , and its components include low-density polyethylene and linear low-density polyethylene, and the mass ratio of the low-density polyethylene to the linear low-density polyethylene is between 2:3 and 1:1.

[0077] As a preference, the first barrier film has an oxygen permeability of 0.9 cm 3 / m 2 day to 2.0cm 3 / m 2 ·The moisture permeability is 3.0g / m 2 Daily up to 5.0g / m 2 day, the thickness of the first barrier film is between 15um and 35um.

[0078] In other embodiments, Figure 5 As shown, the first barrier film includes nine layers of sub-functional films. Specifically, the first barrier film includes: a first layer; a second layer; a third layer; a fourth layer; a fifth layer; a sixth layer; a seventh layer; an eighth layer; a ninth layer;

[0079] The second to seventh layers are secondary barrier layers 113, each comprising low-density polyethylene and metallocene polyethylene in a mass ratio of 4:1 to 9:1.

[0080] The first layer and the eighth layer are outer barrier layers 111, which have the same composition and include linear low-density polyethylene, preferably 100 wt% linear low-density polyethylene;

[0081] The ninth layer is the first composite layer 112 , and its components include low-density polyethylene and linear low-density polyethylene, and the mass ratio of the low-density polyethylene to the linear low-density polyethylene is between 2:3 and 1:1.

[0082] In some embodiments, as Figure 4 As shown, the heat-sealing film includes nine layers of sub-functional films. Specifically, the heat-sealing film includes: a first layer; a second layer; a third layer; a fourth layer; a fifth layer; a sixth layer; a seventh layer; an eighth layer; and a ninth layer. Layers one through eight comprise linear low-density polyethylene (LLDPE) and cyclic olefin copolymer (COCO) in a weight ratio of 7:3 to 9:1. The ninth layer comprises low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) in a weight ratio of 4:1 to 9:1. The heat-sealing film has a thickness of 30 to 60 μm.

[0083] In some embodiments, as Figure 3 As shown, the aluminized film includes nine layers of sub-functional films and an aluminized layer. Specifically, the aluminized film 12 includes an aluminized substrate 121 and an aluminized layer 120. The aluminized substrate 121 includes: a first layer; a second layer; a third layer; a fourth layer; a fifth layer; a sixth layer; a seventh layer; an eighth layer; and a ninth layer. The first to ninth layers have the same composition and include high-density polyethylene, preferably 100 wt% high-density polyethylene. The overall oxygen permeability of the aluminized film is 8.0 cm 3 / m 2 day to 15.0cm 3 / m 2 ·The moisture permeability is 1.0g / m 2 Daily up to 2.0 g / m 2 The thickness of the aluminum coating ranges from 25um to 70um, and the thickness of the aluminum coating ranges from 2.9 angstroms to 3.5 angstroms.

[0084] As a preference, Figure 1 and Figure 6 As shown, the first barrier film, aluminized film and heat-sealing film having nine layers of sub-functional films and corresponding components are compounded to form a bag to obtain a barrier bag. Figure 1 It is a high barrier bag with EVOH component. Figure 6 Barrier bags without EVOH have higher oxygen and moisture barrier properties than those without. The overall structure enables the bag to have high oxygen and moisture barrier properties (less than or equal to 0.5), high light-blocking properties, high temperature resistance, and higher strength. Different components can be added to meet different performance requirements based on actual usage scenarios.

[0085] The first barrier film and the aluminized film are compounded by an adhesive, and the aluminized film and the heat-sealing film are compounded by an adhesive. The present invention does not specifically limit the components of the adhesive, and the adhesive is not limited to commercially available glues such as polyurethane composite glue and polyethylene adhesive resin. The adhesive used in the present invention may further contain tackifying resins, plasticizers, drying delay agents, defoaming agents, thickeners, waxes, preservatives, colorants, etc. as needed. Preferably, the compounding method is solvent-free compounding, and the compounding method without solvent is more environmentally friendly. In addition, in order to improve the composite strength, the functional film is corona-treated on the surface of the composite to make the surface rougher and improve the composite strength. Preferably, the corona value is between 38 dynes and 42 dynes. The functional film subjected to corona treatment includes: the surface of the innermost sub-functional film of the first barrier film and the surface of the outermost sub-functional film of the heat-sealing film.

[0086] The present invention does not impose any specific limitations on the application of barrier bags. Barrier bags can be customized based on actual performance requirements. By adjusting the component ratio, the number of layers, structure, placement, and thickness of the multi-layered functional films, and other parameters, functional films with different properties can be produced. These functional films can be combined to form barrier bags with different functions, allowing for diverse applications. As some alternative embodiments, the barrier bags of the present invention can be facial mask bags, food packaging bags, coffee bags, milk powder packaging bags, pharmaceutical packaging bags, retortable bags, shopping bags, and the like.

[0087] like Figure 7 As shown in FIG. 1 , as an embodiment of the method for making a barrier bag of the present invention, the specific steps include:

[0088] In step S100, EVOH, LDPE, MPE and LLDPE in a first set ratio are added to a multilayer co-extruder, blown into a plastic film, and then longitudinally stretched to obtain a first barrier film;

[0089] In step S200, HDPE of a second set ratio is added to a multi-layer co-extruder, blown into a plastic film, and then longitudinally stretched to obtain an aluminum-plated substrate;

[0090] In step S300, the aluminum-plated substrate is aluminum-plated to obtain an aluminum-plated film;

[0091] In step S400, LLDPE, cycloolefin, and LDPE in a third set ratio are added to a multilayer co-extruder, blown into a plastic film, and then longitudinally stretched to obtain a heat-sealed film;

[0092] In step S500, the first barrier film, the aluminized film and the heat-sealing film are compounded to obtain the above-mentioned barrier bag.

[0093] The barrier bag produced by the above-mentioned production method is the barrier bag provided in the first aspect of the present disclosure.

[0094] Films made by multi-layer co-extrusion have multiple sub-functional films, and the formula can be more flexible and varied. The component combination of each sub-functional film makes each sub-functional film have different properties, thereby enhancing the different properties of the overall functional film, making the functional film have better comprehensive performance (higher barrier properties, higher mechanical properties such as strength, stiffness and toughness, better gloss, higher temperature resistance, etc.), broadening the scope of application engineering of barrier bags and solving challenging industrial problems.

[0095] In addition, the multi-layer co-extruded film undergoes longitudinal stretching to increase its orientation in the longitudinal direction, thereby improving its stiffness, optical properties, and barrier properties. MDO stretching equipment utilizes multiple rollers that undergo four stages: preheating, stretching, annealing, and cooling.

[0096] The weight ratio of polyethylene used as the raw material component of the present invention exceeds 90%. By adopting the production method of the present invention, this single-material barrier bag can replace thick aluminum to play the role of oxygen and moisture barrier, greatly reducing the aluminum content and being more conducive to recycling. Compared with conventional polyethylene packaging bags, various performances are further improved, with high barrier properties, high strength, high stiffness, high gloss, high temperature resistance and other properties.

[0097] In step S100, the first barrier film is preferably stretched longitudinally at a ratio of 5 to 5.5. The present invention does not impose any particular limitations on other methods for manufacturing the first barrier film. For example, to increase the composite strength between the first barrier film and the adjacent functional film, the surface of the first barrier film may be subjected to a corona treatment to increase surface roughness. For another example, a pattern may be printed on the inner surface of the first barrier film for the purpose of printing a logo.

[0098] In step S200, preferably, the longitudinal stretching ratio of the aluminum-plated substrate is between 1 and 1.5. The present invention does not specifically limit other methods for making the aluminum-plated substrate. For example, the surface of the aluminum-plated substrate can also be corona treated to increase the surface roughness, so that the aluminum layer can be well adhered to the surface during subsequent aluminum plating, thereby increasing the adhesion of the aluminum plating on the surface of the aluminum-plated substrate, making the aluminum plating layer more firmly bonded to the surface of the aluminum-plated substrate, and compensating for the shortcoming of the weak bonding force of the aluminum plating of the PE film causing a decrease in barrier properties.

[0099] In step S300, the present invention does not specifically limit the aluminum plating method, and it is only necessary to provide the aluminum plating layer on the surface of the aluminum-plated substrate in step S200 and adhere to the surface of the aluminum-plated substrate. For example, a vacuum sputtering aluminum plating method can be used.

[0100] In step S400, preferably, the longitudinal stretching ratio of the heat-sealing film is between 1 and 1.5 times.

[0101] In step S500, laminating the first barrier film, the aluminized film, and the heat-sealing film includes laminating the first barrier film, the aluminized film, and the heat-sealing film using an adhesive. The present invention does not specifically limit the laminating method. For example, a dry laminating method can be used, in which an adhesive (glue) is applied to a plastic film, then dried in a drying oven to evaporate excess solvent, and then pressed together with another plastic film or an aluminized layer using a hot pressing roller. Another example is a wet laminating method, in which an adhesive (glue) is applied to a plastic film or an aluminized layer, pressed together with another plastic film or an aluminized layer, and then dried in a drying oven. Another example is a solventless laminating method, in which a plastic film pre-coated with a hot melt adhesive layer is pressed together with another plastic film using a hot roller.

[0102] The present invention will be further described below with reference to the examples.

[0103] Example

[0104] Example 1

[0105] The first barrier film is prepared, and the specific steps include:

[0106] The feeding machine grabs the raw materials of the corresponding components according to the set ratio and adds them to the co-extruder. The components and set ratios used in each layer are as follows: first layer: 100% linear low-density polyethylene; second layer: 80% low-density polyethylene and 20% metallocene polyethylene; third layer: 80% low-density polyethylene and 20% metallocene polyethylene; fourth layer: 100% polyolefin adhesive resin; fifth layer: 100% vinyl alcohol-ethylene copolymer; sixth layer: 100% polyolefin adhesive resin; seventh layer: 80 low-density polyethylene and 20% metallocene polyethylene; eighth layer: 100% linear low-density polyethylene; ninth layer: 40% low-density polyethylene and 60% linear low-density polyethylene;

[0107] The extruder melts and plasticizes the raw materials in the above proportions in sequence and then feeds them into a die head for extrusion and blow molding to form a film, thereby obtaining a primary barrier film with a nine-layer co-extrusion structure;

[0108] The primary barrier film is longitudinally stretched at a stretching ratio of 5 to obtain a first barrier film, wherein the thickness ratio of the first to ninth layers of the first barrier film is 2:1:2:1:2:2:3:2:4;

[0109] The specific steps of preparing the aluminum-plated film include:

[0110] The aluminized film is prepared using the same method as the first barrier film, except that the raw materials and the ratio of 100% high-density polyethylene are added to the nine-layer co-extruder. The extruder melts and plasticizes the raw materials in the above ratio in sequence and then feeds them into the die head for extrusion and blow molding to form a film, thereby obtaining the first aluminized substrate;

[0111] The first aluminized substrate is longitudinally stretched, and the stretching multiple is set to 1, to obtain an aluminized substrate, the thickness ratio of the first layer to the ninth layer of the aluminized substrate is 2:1:2:1:2:2:3:2:4;

[0112] The aluminized substrate is vacuum aluminized to obtain an aluminized film;

[0113] The heat-seal film is prepared by the following steps:

[0114] The heat-seal film is prepared by the same method as the first barrier film, except that the raw materials and the proportions of each layer are as follows: the first layer to the eighth layer are 70% linear low-density polyethylene and 30% cyclic olefins; the ninth layer: 80% low-density polyethylene and 20% linear low-density polyethylene, the extruder melts and plasticizes the above-mentioned raw materials in the above-mentioned proportions in turn and then sends them into the die to be extruded and blow-molded into a film, to obtain a first heat-seal film with a nine-layer co-extrusion structure;

[0115] The first heat-seal film is longitudinally stretched, and the stretching multiple is set to 1, to obtain a heat-seal film, the thickness ratio of the first layer to the ninth layer of the heat-seal film is 2:1:2:1:2:2:3:2:4;

[0116] The first barrier film, the aluminized film, and the heat-seal film are compounded by solvent-free method through glue to obtain a barrier bag 1.

[0117] Example 2

[0118] The barrier bag is prepared by the same materials and preparation method as in Example 1, except that the first barrier film is set to a stretching multiple of 5.5, and the aluminized film is set to a stretching multiple of 1.5, to obtain a barrier bag 2.

[0119] Example 3

[0120] The barrier bag is prepared by the same materials and preparation method as in Example 1, except that the raw materials and the proportions of the extruder of the fourth layer, the fifth layer, and the sixth layer of the first barrier film are all 80% low-density polyethylene and 20% metallocene polyethylene, to obtain a barrier bag 3.

[0121] Example 4

[0122] The barrier bag is prepared by the same materials and preparation method as in Example 3, except that the first barrier film is set to a stretching multiple of 5.5, and the aluminized film is set to a stretching multiple of 1.5, to obtain a barrier bag 4.

[0123] Comparative Example 1

[0124] This product does not utilize the components and structure of the present invention and is a common barrier bag currently available on the market. Its specific structure includes a three-layer composite of KOPP / NY / CPE. KOPP is a biaxially oriented polypropylene film coated with polyvinylidene chloride, NY is a nylon filter membrane, and CPE is a chlorinated polyethylene film. This barrier bag is a commonly used commercially available material.

[0125] Test Case

[0126] A set of test items were performed on the barrier bags of the examples and the barrier bags of the comparative examples. The specific test items are shown in Table 1. The specific results of the examples and the comparative examples are shown in Table 1.

[0127] The use of the EVOH material of the present invention in Examples 1 and 2 can further improve the oxygen and moisture barrier properties of the barrier bag, and also improve the longitudinal tensile strength of the film. However, the EVOH material of the present invention is not used in Examples 3 and 4 and the comparative example, so the corresponding oxygen and moisture barrier properties are both lower than those in Examples 1 and 2.

[0128] Example 1 uses a 5-fold longitudinally stretched printed film, adds 100% vinyl alcohol-ethylene copolymer to the middle layer of the printed film, and uses a 1-fold longitudinally stretched aluminized film. The performance of the prepared barrier bag meets the standard requirements, and the oxygen permeability is 1.5cc / m 2 *day, moisture permeability is 1.6 g / m 2 *day, heat seal strength (top seal) is 3.7kgf / 15mm, heat seal strength (bottom seal) is 3.5kgf / 15mm, tensile strength in MD direction is 4.6 kgf / 15mm, TD direction is 3.4 kgf / 15mm, thickness is 108um, weight is 104g / m 2 , and the rest of the test performances are within the qualified range.

[0129] Compared with Example 1, Example 2 increases the stretching ratio of the first barrier film and the aluminized film. The stretching ratio of the first barrier film is increased from 5 times to 5.5 times, and the stretching ratio of the aluminized film is increased from 1 times to 1.5 times. The heat sealing strength and tensile strength of the barrier bag prepared are significantly improved compared with Example 1, and the oxygen permeability is 0.8 cc / m 2 *day, moisture permeability is 0.9 g / m 2 *day, heat seal strength (top seal) is 4.6kgf / 15mm, heat seal strength (bottom seal) is 4.9kgf / 15mm, tensile strength in MD direction is 6.5kgf / 15mm, TD direction is 5.2 kgf / 15mm, thickness is 108um, weight is 104g / m 2 , and the rest of the test performances are within the qualified range.

[0130] Example 3 does not add vinyl alcohol-ethylene copolymer. The stretch ratio is the same as that of Example 1. The oxygen barrier performance is significantly reduced, the moisture barrier performance is slightly reduced, the heat seal strength and tensile strength are slightly reduced, and the oxygen permeability is 3.4 cc / m 2 *day, moisture permeability is 1.5 g / m 2 *day, heat seal strength (top seal) is 4.2kgf / 15mm, heat seal strength (bottom seal) is 4kgf / 15mm, tensile strength in MD direction is 4.5 kgf / 15mm, TD direction is 3.9 kgf / 15mm, thickness is 143um, weight is 134g / m 2 , and the rest of the test performances are within the qualified range.

[0131] Example 4 does not add vinyl alcohol-ethylene copolymer. The stretch ratio is the same as that of Example 2. The oxygen barrier performance is significantly reduced, the tensile strength is reduced, the heat seal strength is increased, the oxygen barrier performance is significantly reduced, the moisture barrier performance is slightly reduced, the heat seal strength and tensile strength are slightly reduced, and the oxygen permeability is 3.1 cc / m 2 *day, moisture permeability is 0.9 g / m 2 *day, heat seal strength (top seal) is 3.8 kgf / 15mm, heat seal strength (bottom seal) is 3.1 kgf / 15mm, tensile strength in MD direction is 5.3 kgf / 15mm, TD direction is 4.7 kgf / 15mm, thickness is 143um, weight is 134g / m 2 , and the rest of the test performances are within the qualified range.

[0132] The comparative example did not adopt the barrier bag structure and components of the present invention, and its performance was inferior to that of the barrier bag of the present invention, with an oxygen permeability of 8.5 cc / m 2 *day, moisture permeability is 2.3 g / m 2 *day, heat seal strength (top seal) is 3.2 kgf / 15mm, heat seal strength (bottom seal) is 3.2 kgf / 15mm, tensile strength in MD direction is 3.6 kgf / 15mm, TD direction is 2.3 kgf / 15mm, thickness is 68um, weight is 68g / m 2 , and the rest of the test performances are within the qualified range.

[0133] Table 1

[0134]

[0135] In summary, the barrier bag using the structure and components of the present invention has higher oxygen and moisture barrier properties, higher tensile strength and heat sealing strength than the comparative example. The increase in the longitudinal stretching ratio will further improve the oxygen and moisture barrier properties, tensile strength and heat sealing strength of the barrier bag of the present invention. In addition, the barrier bag of the present invention with the addition of EVOH component has higher oxygen and moisture barrier properties than the barrier bag of the present invention without EVOH. Different components can be added according to the actual usage scenario to meet different performance requirements.

[0136] The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

[0137] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A barrier bag, characterized in that: The barrier bag comprises a multilayer functional film stacked in a thickness direction, wherein at least one layer of the functional film comprises a multilayer sub-functional film, the multilayer sub-functional film being integrated into one by multi-layer co-extrusion, the multilayer functional film having an oriented lamellar structure by longitudinal stretching, and the polyethylene weight ratio of the barrier bag being greater than or equal to 90%; The multilayer functional film includes a first barrier film, an aluminized film and a heat-sealing film, wherein the first barrier film is located at the outermost layer, the heat-sealing film is located at the innermost layer, the aluminized film includes multiple sub-functional films, and the barrier bag further includes an aluminized layer, which is arranged at the outermost side of the aluminized film and is respectively bonded to the sub-functional film of the first barrier film and the sub-functional film of the aluminized film; The aluminized film comprises: nine layers of the sub-functional films; the first to ninth layers of the aluminized film have the same components and include high-density polyethylene, the thickness of the aluminized film is between 25 μm and 70 μm, and the thickness of the aluminized layer is between 2.9 angstroms and 3.5 angstroms; The first barrier film includes nine layers of sub-functional films; the fifth layer of the first barrier film includes ethylene-vinyl alcohol polymer, the fourth and sixth layers of the first barrier film have the same components and include polyolefin adhesive resin, the first and eighth layers of the first barrier film have the same components and include linear low-density polyethylene, the second, third, and seventh layers of the first barrier film have the same components and include low-density polyethylene and metallocene polyethylene, and the mass ratio of the low-density polyethylene to the metallocene polyethylene is between 4:1 and 9:1, the ninth layer of the first barrier film includes low-density polyethylene and linear low-density polyethylene, and the mass ratio of the low-density polyethylene to the linear low-density polyethylene is between 2:3 and 1:1, and the thickness of the first barrier film is between 15 μm and 35 μm; The stretching ratio of the first barrier film is between 5 times and 5.5 times, the stretching ratio of the aluminized film is between 1 times and 1.5 times, and the functional film comprises nine layers of co-extrusion plus longitudinal stretching.

2. The barrier bag according to claim 1, characterized in that: The components of the sub-functional membrane include polyethylene and its copolymers having at least one molecular chain length with at least one degree of branching.

3. The barrier bag according to claim 2, characterized in that: The components of the sub-functional film include at least one of low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, metallocene polyethylene, ethylene-vinyl alcohol polymer, and cyclic olefin copolymer.

4. The barrier bag according to claim 3, characterized in that: The number of layers of the sub-functional films of the functional film is an odd number, and the number of layers of the sub-functional films of the functional film does not exceed 11 layers.

5. The barrier bag according to claim 1, characterized in that: The first barrier film includes: nine layers of the sub-functional films; the components of the second to seventh sub-functional films of the first barrier film all include low-density polyethylene and metallocene polyethylene in a mass ratio between 4:1 and 9:1, the components of the first sub-functional film and the eighth sub-functional film of the first barrier film are the same and include linear low-density polyethylene, and the components of the ninth sub-functional film of the first barrier film include low-density polyethylene and linear low-density polyethylene and the mass ratio of the low-density polyethylene and the linear low-density polyethylene is between 2:3 and 1:

1.

6. The barrier bag according to any one of claims 1 to 5, characterized in that: The heat-sealing film includes: nine layers of the sub-functional films; components of the first to eighth layers of the heat-sealing film include linear low-density polyethylene and cyclic olefin copolymer, and the mass ratio of the low-density polyethylene to the cyclic olefin copolymer is between 7:3 and 9:1; components of the ninth layer of the heat-sealing film include low-density polyethylene and linear low-density polyethylene, and the mass ratio of the low-density polyethylene to the linear low-density polyethylene is between 4:1 and 9:1; the thickness of the heat-sealing film is between 30 μm and 60 μm.

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