Novel environment-friendly foaming composite sheet and packaging hose

Abstract

The invention discloses a novel environment-friendly foaming composite sheet and a packaging hose. According to the novel environment-friendly foaming composite sheet, through the special foaming material structure and process, the strength problem caused by the loose structure of a foaming film layer is solved; according to the technology, through a reasonable sheet interlayer structure and printing process design, the technical problems that the interlayer peeling strength is weak, paste is prone to permeating and adsorbing, printing is not solid and becomes virtual and the like due to the fact that a foaming material is loose in structure are effectively solved, and the purposes of environment-friendly plastic reduction and green sustainable development are achieved; and moreover, the product package is endowed with unique appearance textures, and green, environment-friendly and differentiated product packages are provided for brands and consumers.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging containers and materials, and particularly relates to a novel environmentally friendly foamed composite sheet and a packaging hose. Background Art

[0002] Traditional foamed materials have many problems due to their loose structure and uneven surface. Packaging hoses prepared using traditional foamed materials have problems such as weak interlayer bonding force, low strength, easy adsorption of the contents, as well as poor printing and unsatisfactory color saturation. Among the current foamed packaging materials on the market, the bonding strength between the foamed film layer and other composite layers is low, and the contents (paste) are easily adsorbed. Further, due to the loose structure of the existing foamed materials, there may also be surface unevenness. Based on this, there is an urgent need to develop a novel environmentally friendly foamed composite sheet and a packaging hose. Summary of the Invention

[0003] In order to overcome the deficiencies and drawbacks of the prior art, the primary object of the present invention is to provide a novel environmentally friendly foamed composite sheet. This composite sheet solves many problems brought about by the loose structure and uneven surface of traditional foamed materials.

[0004] Another object of the present invention is to provide a preparation method for the novel environmentally friendly foamed composite sheet.

[0005] Another object of the present invention is to provide a novel environmentally friendly foamed composite packaging hose.

[0006] The primary object of the present invention is achieved through the following technical solutions:

[0007] A novel environmentally friendly foamed composite sheet, comprising an outer layer, a first bonding layer, a foamed film layer, a second bonding layer, and an inner layer. The outer layer is bonded to the foamed film layer through the first bonding layer, and the foamed film layer is bonded to the inner layer through the second bonding layer. The foamed film layer has a (2n + 1)-layer sandwich structure, where n is a positive integer. The (n + 1)-th layer of the foamed film layer is the middle core layer, and surface layer structures are symmetrically arranged on both sides of the middle core layer. The middle core layer is a gradient foamed PE layer, and the surface layer structures on both sides are PE layers added with a modified reinforcing agent.

[0008] Preferably, both the outer layer and the inner layer are three-layer PE film structures (modified high-strength PE layers), and the thickness ratio of the three-layer PE films is 1:3:1. The PE film is made of 50 - 70% by mass of high-density polyethylene material, 10 - 20% of poly-α-olefin, and 20 - 30% of linear low-density polyethylene ((LLDPE)). The density range of the high-density polyethylene material is 0.930 g / cc to 0.970 g / cc.

[0009] Preferably, the foamed film layer is prepared from a polar copolymer PE material added with 2-5% by mass of a modified reinforcing agent; the modified reinforcing agent is one of modified nano-silica (SiO 2 ), carbon fiber or natural fiber; the polar copolymer PE is ethylene-vinyl acetate copolymer (EVA).

[0010] Preferably, n is 1 or 2 in the foamed film layer.

[0011] Preferably, the adhesive materials of the first adhesive layer and the second adhesive layer are polar copolymer PE materials added with 4-10% by mass of a modified tackifier; the modified tackifier is maleic anhydride grafted PE material, and the high-polarity copolymer PE material is EVA.

[0012] Preferably, the thickness of the novel environmentally friendly foamed composite sheet is 300u-500u.

[0013] Preferably, in the novel environmentally friendly foamed composite sheet, the outer layer thickness is 50u, the first adhesive layer thickness is 20u, the foamed film layer thickness is 60u, the second adhesive layer thickness is 20u, and the inner layer thickness is 150u.

[0014] Preferably, the novel environmentally friendly foamed composite sheet further includes a barrier layer and a third adhesive layer. The outer layer and the foamed film layer are adhered through the first adhesive layer, the foamed film layer and the barrier layer are adhered through the second adhesive layer, and the barrier layer and the inner layer are adhered through the third adhesive layer.

[0015] Preferably, the barrier layer is a polyvinyl alcohol (EVOH) barrier layer, and the third adhesive layer material is a polyethylene copolymer.

[0016] Preferably, in the novel environmentally friendly foamed composite sheet, the outer layer thickness is 50u, the first adhesive layer thickness is 20u, the foamed film layer thickness is 60u, the second adhesive layer thickness is 20u, the barrier layer thickness is 50u, the third adhesive layer thickness is 20u, and the inner layer thickness is 150u.

[0017] Preferably, the novel environmentally friendly foamed composite sheet further includes a protective layer and a UV glue layer. The protective layer and the outer layer are adhered through the UV glue layer, the outer layer and the foamed film layer are adhered through the first adhesive layer, and the foamed film layer and the inner layer are adhered through the second adhesive layer.

[0018] Preferably, the protective layer is a high-strength PE layer.

[0019] Preferably, in the novel environmentally friendly foamed composite sheet, the outer layer has a thickness of 80u, the UV glue layer has a thickness of 5u, the outer layer is 80u, the first adhesive layer has a thickness of 25u, the second adhesive layer has a thickness of 25u, the foamed film layer has a thickness of 100u, and the inner layer has a thickness of 110u.

[0020] Another object of the present invention is achieved by the following technical solutions:

[0021] A preparation method of a novel environmentally friendly foamed composite sheet comprises the following steps:

[0022] (1) Preparation of the foamed film layer: The foamed film layer is prepared by a blown film process. The foamed film layer is a (2n + 1)-layer sandwich structure, where n is a positive integer; the (n + 1)-th layer of the foamed film layer is the middle core layer, and surface layer structures are symmetrically arranged on both sides of the middle core layer of the foamed film layer; the middle core layer is a gradient foamed PE layer, and the surface layer structures on both sides are prepared by a novel gradient foaming technology using high-density PE materials added with modified reinforcing agents.

[0023] (2) Preparation of the outer layer and the inner layer: Both the outer layer and the inner layer are completed by a blown film or casting process, and a three-layer PE film structure is adopted to help improve the overall toughness and impact resistance of the sheet.

[0024] (3) Preparation of the composite sheet: The outer layer, the foamed film layer, and the inner layer are sequentially combined by an extrusion compounding or glue compounding process using the first adhesive layer and the second adhesive layer respectively. The outer layer and the inner layer are both three-layer PE film structures, the foamed film layer is the sandwich structure foamed film layer prepared in step (1), and the first adhesive layer and the second adhesive layer are prepared from high-polarity copolymer PE materials added with 4-10% by mass of modified tackifiers.

[0025] (4) Printing of the composite sheet: A modified primer material with high transparency, low viscosity, and high leveling property is used to perform full-surface coating printing on the composite sheet prepared in step (3) to obtain a novel environmentally friendly foamed composite sheet.

[0026] In the present invention, the surface layer structures on both sides use high-density PE materials added with modified reinforcing agents, which can help improve the mechanical properties of the foamed film, as well as the tensile strength and impact resistance of the film. The surface layer structures maintain a relatively high density and small bubble sizes, while the middle core layer gradually becomes looser and the bubble sizes increase, ensuring surface strength while also retaining the internal lightness and buffering characteristics.

[0027] The addition of the modified tackifier in the present invention can help form stronger chemical bonding bonds, thereby improving the interlayer peel strength.

[0028] Preferably, the modified primer material with low viscosity, high transparency, and high leveling property in step (3) is prepared by introducing a high-purity and high-transparency monomer into the main resin to polymerize and generate a low-viscosity linear prepolymer, then adding an efficient leveling agent and mixing under low-frequency vibration; the main resin, high-purity and high-transparency monomer, and low-viscosity linear prepolymer are formulated according to a mass ratio of 3.5:4.5:2; the main resin is methacrylate, the high-purity and high-transparency monomer is hydroxyethyl acrylate, and the efficient leveling agent is polyether-modified silicone oxide.

[0029] Preferably, the low-frequency vibration mixing temperature is 4 - 10°C, and the low-frequency vibration refers to 500 - 800 Hz.

[0030] Among them, the reason for choosing to mix the resin under low-frequency vibration is to ensure that the viscosity of the mixed resin does not increase, while reducing bubbles, and finally obtaining a resin material with high transparency, low viscosity, and high leveling property.

[0031] Among them, the reason for choosing the modified primer material with low viscosity, high transparency, and high leveling property in step (3) is that the primer has low viscosity and good leveling property, which can improve the coating thickness, better fill the surface, and can be well colored without a very thick ink layer. At the same time, due to the high transparency of the primer material, the foamed texture can be well presented.

[0032] Preferably, the coating and printing in step (4) can achieve surface printing or reverse printing, and the coating and printing process includes one of letterpress printing, flexographic printing, gravure printing, offset printing, and screen printing; the coating and printing anilox roll is 200 - 400L.

[0033] Regarding the printing challenges brought by the uneven surface of the foamed material, it can be solved by the modified primer before printing.

[0034] Another object of the present invention is achieved by the following technical solution:

[0035] A new type of environmentally friendly foamed composite packaging hose, including a tube cap and a tube body, and the tube body is prepared from a new type of environmentally friendly foamed composite sheet.

[0036] Preferably, this new type of environmentally friendly foamed composite packaging hose cuts the printed sheet according to the hose specifications (diameter, length), and realizes the one-step completion of tube rolling, welding seam, shoulder injection, and capping through a high-speed tube-making device.

[0037] The foamed film layer of the present invention has the following characteristics:

[0038] 1) Special foaming structure design: By introducing 2 - 5% of a modified reinforcing agent, such as modified nano-silica (SiO 2) Carbon fiber or natural fiber is used to help improve the mechanical properties of the foamed film, as well as the tensile strength and impact resistance of the film. An (n + 1)-layer sandwich structure is selected, where n is an even number. The middle layer is a foamed PE layer, and polyethylene with a higher density is selected on both sides to help improve the overall strength of the film. Technologically, the foaming temperature is appropriately increased and the foaming pressure is controlled to avoid excessive expansion and too large foaming pore diameters during the foaming process, thereby maintaining the compactness of the structure.

[0039] 2) The new gradient foaming technology is adopted to achieve a progressive distribution of the internal bubble structure of the material, that is, the film surface layer maintains a relatively high density and small bubble size, while it gradually becomes loose near the core layer and the bubble size gradually increases. This can ensure the surface strength while retaining the internal light weight and buffering characteristics, making the film gradually become loose from the surface layer to the core layer, ensuring both the surface strength and the internal buffering performance.

[0040] 3) In addition to the special foamed film layer in the composite sheet, the composite sheet also adopts an auxiliary strengthening structure. The inner and outer layers adopt a three-layer PE film structure, preferably a 1:3:1 structure. The multi-layer PE film contains 50 - 70% high-density polyethylene material, and the density ranges from 0.930 g / cc to 0.970 g / cc, as well as 10 - 20% poly-α-olefin and 20 - 30% linear low-density polyethylene to improve the overall toughness and impact resistance strength of the sheet. Between the inner layer and the foamed film layer, a high-barrier material (barrier layer), such as ethylene vinyl alcohol, is used to prevent the content from permeating outwards and being adsorbed by the foamed film layer.

[0041] 4) Due to the uneven foaming surface, it is difficult to ensure the bonding strength between the foamed film layer and other composite layers. In the composite process, a copolymer PE with a higher polarity (such as EVA) is used as the bonding layer, and a modified tackifier (such as maleic anhydride grafted PE, 4 - 10%) is appropriately added to help form stronger chemical bonding, thereby improving the interlayer peel strength.

[0042] 5) To solve the problems of blurry, uneven printing and insufficient color saturation caused by the uneven surface of the foam, a primer needs to be printed before ink printing. The thicker the primer, the better it fills the surface and the better the ink printing. However, if the primer is too thick, it is not easy to flow, and it is also difficult to form a smooth surface. Therefore, a modified primer material with low viscosity, high transparency, and high leveling property is used to help increase the thickness of the primer. While better filling the surface, it can be well colored without using a very thick ink layer. At the same time, due to the high transparency of the modified primer, the texture of the foam is presented. The modified primer material uses methacrylate as the main resin, and at the same time introduces a high-purity and high-transparency monomer (2-hydroxyethyl acrylate), and generates a low-viscosity linear prepolymer by precisely controlling the polymerization conditions (low-temperature polymerization initiation, 4-10 °C). Then, an efficient leveling agent (polyether-modified silicone oxygen) is added, and an oscillating mixing device is used for sufficient dispersion and stirring to ensure that the viscosity of the mixed resin does not increase under the low-frequency vibration state, and at the same time reduce bubbles, and finally obtain a high-transparency, low-viscosity, and high-fluidity resin material. The ratio of the three is the main resin (60%-65%), the high-transparency monomer (30%-38%), and the leveling agent.

[0043] 6) In addition, by adopting the process of inner and outer surface connection printing and compounding, on the basis of the foam texture background, more surface printing decoration effects are given, such as expansion, visual 3D, embossing effects of text and patterns.

[0044] Advantages and beneficial effects of the present invention compared with the prior art:

[0045] (1) The novel environmentally friendly foam composite sheet described in the present invention solves the strength problem caused by the loose structure of the foam film layer through a special foam material structure and process;

[0046] (2) Through reasonable design of the sheet layer structure and printing process, this technology effectively solves the technical problems such as weak interlayer peeling strength, easy penetration and adsorption of paste, uneven printing, and blurriness caused by the loose structure of the foam material. While achieving the purpose of environmental protection and plastic reduction and green sustainable development, it also endows the product packaging with a unique appearance texture, providing green environmental protection and differentiated product packaging for brands and consumers;

[0047] (3) The composite sheet strengthens the structure, solving the problems of low bonding strength between the foam film layer and other composite layers and low adsorption to the contents (paste);

[0048] (4) Due to the uneven surface caused by the loose structure of the foam material, specific designs are made in the printing method, printing process and settings to ensure the coloring of the ink, the saturation of the color, and better presentation of the unique texture appearance effect of the foam material. Description of the Drawings

[0049] Figure 1Structural diagram of the foamed film layer prepared in Example 1;

[0050] Figure 2 Structural diagram of the new environmentally friendly foamed composite sheet prepared in Example 1;

[0051] Figure 3 Structural diagram of the new environmentally friendly foamed composite sheet prepared in Example 2;

[0052] Figure 4 Physical diagram of the new environmentally friendly foamed composite hose packaging prepared in Example 2;

[0053] Figure 5 Structural diagram of the new environmentally friendly foamed composite sheet prepared in Example 3;

[0054] Among them, the middle core layer - 1031, the surface layer mechanism - 1032;

[0055] Outer layer - 101, first bonding layer - 102, foamed film layer - 103, second bonding layer - 104, inner layer - 105, barrier layer 106, third bonding layer - 107, protective layer - 108, UV glue layer - 109. Detailed implementation manners

[0056] The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the implementation manners of the present invention are not limited thereto.

[0057] Example 1

[0058] Preparation method of the new environmentally friendly foamed composite sheet described in this example:

[0059] (1) Processing of the foamed film layer: A three - layer sandwich structure is adopted. High - density PE is selected on both sides to help improve the overall strength of the film, and a modified reinforcing agent (modified nano - silica) is introduced to help improve the mechanical properties of the foamed film, as well as the tensile strength and impact resistance of the film. The new gradient foaming technology is selected in the process, so that the surface layer maintains a relatively high density and small bubble size, while the core layer gradually becomes looser and the bubble size increases, ensuring the surface strength while also retaining the internal light weight and buffering characteristics. The overall thickness of the foamed film layer is controlled within the range of 50 - 100 microns.

[0060] (2) Composite sheet processing: The outer layer uses a high-transparency polyethylene film, and the inner layer of PE uses modified high-strength PE to enhance the overall toughness and impact resistance of the sheet. Between the inner layer and the foamed film layer, a high-barrier material is supplemented, such as a metal barrier material, ethylene-vinyl alcohol (EVOH), to prevent the contents from permeating from the inside to the outside and being adsorbed by the foamed film layer. Each layer of the composite sheet, including the outer layer, the foamed film layer, the barrier layer, and the inner layer, is combined by an extrusion lamination process. The layers are sequentially bonded together through a first adhesive layer, a second adhesive layer, and a third adhesive layer. Among them, the first adhesive layer and the second adhesive layer use a copolymer PE with a relatively high polarity (such as EVA) and appropriately add a modified tackifier (such as maleic anhydride grafted PE) as the bonding layer to help form stronger chemical bonding bonds, thereby enhancing the interlayer peel strength; the material of the third adhesive layer is a polyethylene copolymer. The thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer extruded are usually above 20 microns. In addition to the extrusion lamination process, polyurethane or solvent-free glue can also be used through a dry lamination process to combine the layers to form a composite sheet.

[0061] (3) Printing of the composite sheet: Before printing the composite sheet, a modified primer material (polyolefin copolymer) with low viscosity, high transparency, and high leveling property is used to coat the entire surface of the composite sheet to provide a flat surface. Since the primer has low viscosity and good leveling property, the coating thickness can be increased, and the surface can be better filled. Good coloring can be achieved without a very thick ink layer. The coating anilox roll for the primer material is selected to be 200 - 400L. At the same time, due to the high transparency of the primer material, the foamed texture is well presented. This embodiment uses surface printing.

[0062] As Figure 1 and Figure 2 shown, the new environmentally friendly foamed composite sheet described in this embodiment includes an outer layer, a first adhesive layer, a foamed film layer, a second adhesive layer, and an inner layer. The total thickness of the new environmentally friendly foamed composite sheet is 300u. Among them, the thickness of the outer layer is 50u, the thicknesses of the first adhesive layer and the second adhesive layer are 20u, the thickness of the foamed film layer is 60u, and the thickness of the inner layer is 150u. The foamed film layer includes an intermediate core layer and two surface layer structures on both sides. The thickness of the intermediate core layer is 20u, and the thickness of the surface layer structure is 20u.

[0063] Example 2

[0064] The preparation method of the new environmentally friendly foamed composite sheet described in this embodiment:

[0065] (1) Processing of the foamed film layer: A three-layer sandwich structure is adopted. High-density PE is selected on both sides to help improve the overall strength of the film, and a modified reinforcing agent (carbon fiber) is introduced to help improve the mechanical properties of the foamed film, as well as the tensile strength and impact resistance of the film. In terms of technology, a new gradient foaming technology is selected to keep the surface layer with a relatively high density and small bubble size, while the core layer gradually becomes looser and the bubble size increases, ensuring surface strength while also retaining the internal light weight and buffering characteristics. The overall thickness of the foamed film layer is controlled within the range of 50 - 100 microns.

[0066] (2) Processing of the composite sheet: The outer layer uses a high-transparency polyethylene film, and the inner layer PE uses modified high-strength PE to enhance the overall toughness and impact resistance of the sheet. Between the inner layer and the foamed film layer, high-barrier materials such as metal barrier materials and ethylene vinyl alcohol (EVOH) are used to prevent the contents from permeating outwards and being adsorbed by the foamed film layer. Each layer of the composite sheet, including the outer layer, foamed film layer, barrier layer, and inner layer, is combined through an extrusion lamination process. The layers are adhered together in sequence through the first adhesive layer, the second adhesive layer, and the third adhesive layer. Among them, the first adhesive layer and the second adhesive layer use a copolymer PE with a relatively high polarity (such as EVA) and appropriately add a modified tackifier (such as maleic anhydride grafted PE) as the bonding layer to help form stronger chemical bonding, thereby enhancing the interlayer peel strength; the material of the third adhesive layer is a polyethylene copolymer. The thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer extruded are usually above 20 microns. In addition to the extrusion lamination process, polyurethane or solvent-free glue can also be used through a dry lamination process to combine the layers to form a composite sheet.

[0067] (3) Printing of the composite sheet: Before printing the composite sheet, a modified primer material (polyolefin copolymer) with low viscosity, high transparency, and high leveling property is used to coat the composite sheet fully to provide a flat surface. Since the primer has low viscosity and good leveling, it can improve the coating thickness, better fill the surface, and can be well colored without a very thick ink layer. The coating anilox roll for the primer material is selected with 200 - 400L. At the same time, due to the high transparency of the primer material, the foaming texture is well presented. This embodiment uses surface printing.

[0068] Such as Figure 1 and Figure 3As shown in the figure, the new environmentally friendly foamed composite sheet described in this embodiment includes an outer layer, a first adhesive layer, a foamed film layer, a second adhesive layer, a barrier layer, a third adhesive layer, and an inner layer. The total thickness of the new environmentally friendly foamed composite sheet is 370u. Among them, the thickness of the outer layer is 50u, the thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer are 20u, the thickness of the foamed film layer is 60u, the thickness of the barrier layer is 50u, and the thickness of the inner layer is 150u. The foamed film layer includes an intermediate core layer and two surface layer mechanisms on both sides. The thickness of the intermediate core layer is 20u, and the thickness of the surface layer mechanism is 20u.

[0069] Further, the foamed film layer includes an intermediate core layer (30u) and two surface layer mechanisms on both sides (15u). The intermediate core layer is a gradient foamed PE layer, and the two surface layer structures on both sides are PE layers added with a modified reinforcing agent (nano-silica). The added modified reinforcing agent helps to improve the overall mechanical properties, tensile strength, and impact resistance of the foamed film layer. Due to the selection of the gradient foaming process for the intermediate core layer of the foamed film layer, the surface layer maintains a relatively high density and small bubble size, while the intermediate core layer gradually becomes looser and the bubble size gradually increases, ensuring the surface strength.

[0070] An EVOH barrier layer is added between the foamed film layer and the inner layer PE to further improve the strength of the composite sheet. More importantly, due to the addition of the EVOH barrier layer, the contents cannot easily penetrate from the inner layer PE to the outside and be adsorbed by the relatively loose foamed film layer, thereby affecting the contents.

[0071] As Figure 4 As shown in the figure is the new environmentally friendly foamed composite packaging hose prepared in this embodiment. The packaging hose includes a tube cap and a tube body, and the tube body is prepared from the new environmentally friendly foamed composite sheet.

[0072] The following table shows the test experiments on the new environmentally friendly foamed composite packaging hose in this embodiment, where the target refers to the performance compliance requirements of the packaging hose prepared by the present invention, and the actual refers to the actual performance of the new environmentally friendly foamed composite packaging hose prepared in this embodiment.

[0073] Item Target Actual Outer layer peel strength ≥5N 9.13 Inner layer peel strength ≥5N 8.38 Burst test 2 bar * 30 sec Pass Drop test 1.5 m, 3 times, 200 g Pass

[0074] Example 3

[0075] The preparation method of the new environmentally friendly foamed composite sheet described in this embodiment refers to Example 2. As Figure 5As shown, the novel environmentally friendly foamed composite sheet prepared in this embodiment includes an outer layer (high-strength PE), a UV glue layer, an intermediate layer (high-strength PE), a first adhesive layer, a foamed film layer, a second adhesive layer, and an inner layer. The total thickness of the novel environmentally friendly foamed composite sheet is 425u. Among them, the thickness of the protective layer is 80u, the thickness of the UV glue layer is 5u, the thickness of the outer layer is 80u, the thicknesses of the first and second adhesive layers are 25u, the thickness of the foamed film layer is 100u, and the thickness of the inner layer is 110u.

[0076] Furthermore, the foamed film layer includes an intermediate core layer (50u) and two side surface layer structures (25u). The intermediate core layer is a gradient foamed PE layer, and the two side surface layer structures are PE layers added with a modified reinforcing agent (carbon fiber). The added modified reinforcing agent helps to improve the overall mechanical properties, tensile strength, and impact resistance of the foamed film layer. Since the gradient foaming process is selected for the intermediate core layer of the foamed film layer, the surface layer maintains a relatively high density and small bubble size, while the intermediate core layer gradually becomes looser and the bubble size gradually increases, ensuring the surface strength. The novel environmentally friendly foamed composite sheet of the present invention adopts inside-out combined printing.

[0077] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A new type of environmentally friendly foamed composite sheet, characterized in that: It includes an outer layer, a first adhesive layer, a foaming film layer, a second adhesive layer and an inner layer, wherein the outer layer and the foaming film layer are bonded to each other through the first adhesive layer, and the foaming film layer and the inner layer are bonded to each other through the second adhesive layer, and the foaming film layer is a (2n+1)-layer sandwich structure, where n is a positive integer; the (n+1)th layer of the foaming film layer is an intermediate core layer, and surface structures are symmetrically arranged on both sides of the intermediate core layer; the intermediate core layer is a gradient foaming PE layer, and the surface structures on both sides are PE layers with modified reinforcing agents added.

2. The novel environmentally friendly foamed composite sheet according to claim 1, characterized in that: The outer layer and the inner layer are both three-layer PE film structures, and the thickness ratio of the three-layer PE film is 1:3:1; the PE film is made of a high-density polyethylene material with a mass fraction of 50-70%, 10-20% poly-alpha olefin and 20-30% linear low-density polyethylene; the density range of the high-density polyethylene material is 0.930g / cc to 0.970g / cc.

3. The novel environmentally friendly foamed composite sheet according to claim 1, characterized in that: The foaming film layer is prepared by adding 2-5% by mass of a modifying reinforcing agent and a polar copolymer PE material; the modifying reinforcing agent is one of modified nano silicon dioxide, carbon fiber or natural fiber; and the polar copolymer PE is ethylene-vinyl acetate copolymer.

4. The novel environmentally friendly foamed composite sheet according to claim 1, characterized in that: The adhesive material of the first adhesive layer and the second adhesive layer is a high-polarity copolymer PE material to which a modified tackifier is added at a mass fraction of 4 to 10%; the modified tackifier is a maleic anhydride grafted PE material, and the high-polarity copolymer PE material is EVA.

5. The novel environmentally friendly foamed composite sheet according to claim 1, characterized in that: The thickness of the novel environmentally friendly foamed composite sheet is 300u-500u.

6. The novel environmentally friendly foamed composite sheet according to any one of claims 1 to 5, characterized in that: The novel environmentally friendly foamed composite sheet also includes a barrier layer and a third adhesive layer. The outer layer is bonded to the foamed film layer through the first adhesive layer, the foamed film layer is bonded to the barrier layer through the second adhesive layer, and the barrier layer is bonded to the inner layer through the third adhesive layer.

7. The novel environmentally friendly foamed composite sheet according to any one of claims 1 to 5, characterized in that: The novel environmentally friendly foamed composite sheet also includes a protective layer and a UV glue layer, wherein the protective layer and the outer layer are bonded via the UV glue layer, the outer layer and the foamed film layer are bonded via a first bonding layer, and the foamed film layer and the inner layer are bonded via a second bonding layer.

8. A method for preparing a novel environmentally friendly foamed composite sheet according to any one of claims 1 to 5, comprising the following steps: (1) Preparation of the foamed film layer: The foamed film layer is prepared by a film blowing process, wherein the foamed film layer is a (2n+1)-layer sandwich structure, where n is an integer; the (n+1)th layer of the foamed film layer is an intermediate core layer, and surface structures are symmetrically arranged on both sides of the intermediate core layer of the foamed film layer; the intermediate core layer is a gradient foamed PE layer, and the surface structures on both sides are prepared by using a high-density PE material added with a modified reinforcing agent using a new gradient foaming technology; (2) Preparation of outer layer and inner layer: Both the outer layer and the inner layer are made by blown film or cast film process, and adopt a three-layer PE film structure to help improve the overall toughness and impact strength of the sheet; (3) Preparation of composite sheet: The outer layer, the foamed film layer and the inner layer are respectively combined by extrusion lamination or glue lamination process using the first adhesive layer and the second adhesive layer, wherein the outer layer and the inner layer are both three-layer PE film structures, the foamed film layer is the sandwich structure foamed film layer prepared in step (1), and the first adhesive layer and the second adhesive layer are prepared from a high-polarity copolymer PE material to which a modified tackifier is added in a mass fraction of 4 to 10%; (4) Printing of composite sheets: A modified primer material with high transparency, low viscosity and high leveling properties is used to perform full-plate coating and printing on the composite sheet prepared in step (3) to prepare a new environmentally friendly foamed composite sheet.

9. The method for preparing the novel environmentally friendly foamed composite sheet according to claim 8, characterized in that: The low-viscosity, high-transparency, high-leveling modified primer material described in step (3) is prepared by introducing a high-purity, high-transparency monomer into a main resin to polymerize a low-viscosity linear prepolymer, adding a high-efficiency leveling agent, and mixing by low-frequency vibration; the main resin, the high-purity, high-transparency monomer and the low-viscosity linear prepolymer are prepared in a mass ratio of 3.5:4.5:2; the main resin is methyl methacrylate, and the high-purity, high-transparency monomer is hydroxyethyl acrylate.

10. A new type of environmentally friendly foam composite packaging hose, characterized in that: It comprises a tube cover and a tube body, wherein the tube body is made from the new environmentally friendly foamed composite sheet according to any one of claims 1 to 7.

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