A self-adhesive composite film and a three-dimensional cushioning bubble bag made of the same

Abstract

The application relates to the field of plastic flexible packaging, and specifically provides a self-adhesive composite film and a three-dimensional buffer bubble bag made of the self-adhesive composite film. The self-adhesive composite film comprises the following three layers of structures in sequence: a high-efficiency buffer layer with a thickness of 1-10 mm, a stable buffer layer with a thickness of 0.1-4 mm, and a printed temperature-resistant layer with a thickness of 0.005-1 mm; the high-efficiency buffer layer is a bubble film, and the stable buffer layer is a pearl wool film; the printed temperature-resistant layer is a PE film which comprises an inner layer, a middle layer and an outer layer; the preparation raw materials of the inner layer comprise low-density polyethylene, medium-density polyethylene, linear low-density polyethylene and high-density polyethylene. The heat bonding temperature and the bonding effect of the PE film and the composite film are improved by optimizing the layer structure of the PE film, the wide sealing edge, the three-dimensional structure and the practicability of the bubble bag made of the composite film are realized, the grammage or the density of the high-efficiency buffer layer and the stable buffer layer is optimized, and the bubble bag also has excellent anti-shock buffering effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plastic flexible packaging, B32B27 / 08, and in particular to a self-adhesive composite film and a three-dimensional cushion bubble bag made of the same. BACKGROUND

[0002] Bubble bags generally have bubble films for shock absorption. These bubble films have a large number of bubble bodies, have the functions of light weight, high elasticity, shock resistance and scratch resistance, and are widely used in cushioning and protective packaging of fragile items such as household goods, glass products and precision instruments. The existing bubble bags are mostly envelope bags, which have a two-side sealing structure and cannot achieve a self-standing effect, which is not convenient for scenarios such as supermarket delivery. This is mainly because the film layer for preparing the bubble bag has poor high-temperature resistance, and various problems occur during heat sealing, which cannot achieve a wider sealing edge, firm sealing and higher heat-sealing adhesive strength, etc. Therefore, it is of great market value to solve the high-temperature resistance of the bubble bag film layer and improve its shock absorption performance.

[0003] Chinese patent CN103522699B discloses a PE film, which is provided with a three-layer structure, each layer of which comprises low-density polyethylene and linear low-density polyethylene, and the inner layer and the middle layer further comprise myrcene to make the PE film have an aromatic odor. However, the heat-sealing strength and tensile strength at break of the PE film are low, and the PE film does not have shock resistance. Chinese patent CN116515144A discloses a double-sided corona double-sided anti-static blown polyethylene film and a packaging bag, the polyethylene film substrate of which is composed of LDPE 50-75%, POE 3-10%, metallocene polyethylene 10-35%, LLDPE 2-10% and HDPE 10-25%, and both sides of the polyethylene film substrate are attached with an anti-static coating, which has good high-temperature resistance and will not be burned through during corona treatment. However, the high-temperature resistance of the polyethylene film substrate is still not enough after removing the anti-static coating, and the polyethylene film substrate does not have shock resistance. SUMMARY

[0004] To solve the above technical problems, the present application first provides a self-adhesive composite film, which comprises the following three layers of structures in sequence: a high-efficiency cushioning layer, a stable cushioning layer and a printed temperature-resistant layer.

[0005] Further, the self-adhesive composite film comprises the following three layers of structures in sequence: a high-efficiency cushioning layer with a thickness of 1-10 mm, a stable cushioning layer with a thickness of 0.1-4 mm and a printed temperature-resistant layer with a thickness of 0.005-1 mm.

[0006] Further, the thickness of the high-efficiency cushioning layer is 1.5-7 mm, preferably 2-5 mm, and more preferably 3-4 mm.

[0007] Further, the thickness of the stable buffer layer is 0.2-3mm, preferably 0.3-2mm, more preferably 0.5-1mm.

[0008] Further, the thickness of the printed temperature-resistant layer is 0.01-0.5mm, preferably 0.02-0.2mm, more preferably 0.03-0.1mm.

[0009] Further, the high-efficiency buffer layer is a bubble film.

[0010] Further, the raw material for preparing the bubble film includes but is not limited to at least one of polyethylene, polypropylene, polylactic acid.

[0011] Preferably, the raw material for preparing the bubble film includes polyethylene.

[0012] Further, the method for preparing the bubble film is not strictly regulated in the present application, and the polyethylene can be cast foamed into a bubble film by using a bubble film machine.

[0013] Further, the grammage of the bubble film is 30-100g / m 2 , preferably 40-80g / m 2 .

[0014] In a preferred embodiment, the grammage of the bubble film is 50-70g / m 2 .

[0015] Further, the stable buffer layer is a pearl cotton film, and the raw material for preparing the pearl cotton film is polyethylene.

[0016] Further, the density of the pearl cotton film is 8-28kg / m 3 ; preferably 15-25kg / m 3 .

[0017] In a preferred embodiment, the density of the pearl cotton film is 18-20kg / m 3 .

[0018] Optimizing the grammage or density of the bubble film and the pearl cotton film improves the compression resistance and buffering performance of the bubble bag, and avoids the damage of the contained object caused by external impact.

[0019] Further, the printed temperature-resistant layer is a PE film, which includes an inner layer, a middle layer and an outer layer.

[0020] Further, the thickness of the inner layer, the middle layer and the outer layer of the PE film is the same.

[0021] Further, the raw material for preparing the inner layer comprises at least one of low density polyethylene (LDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), ultra-high density polyethylene, cross-linked polyethylene (CLPE).

[0022] Preferably, the raw material for preparing the inner layer comprises low density polyethylene, medium density polyethylene, linear low density polyethylene and high density polyethylene.

[0023] Further, the raw material for preparing the inner layer comprises, by total mass: 5-25% low density polyethylene, 40-80% medium density polyethylene, 10-30% linear low density polyethylene and 3-15% high density polyethylene.

[0024] Preferably, the raw material for preparing the inner layer comprises, by total mass: 6-20% low density polyethylene, 50-70% medium density polyethylene, 15-25% linear low density polyethylene and 5-13% high density polyethylene.

[0025] Further, the density of the low density polyethylene in the inner layer is 0.91-0.93 g / cm 3 , preferably 0.92-0.93 g / cm 3 .

[0026] Further, the melt flow rate of the low density polyethylene in the inner layer at 190°C / 2.16 kg is 1.0-4.0 g / 10 min, preferably 1.5-3.0 g / 10 min.

[0027] In a preferred embodiment, the melt flow rate of the low density polyethylene in the inner layer at 190°C / 2.16 kg is 1.7-2.2 g / 10 min.

[0028] Further, the melt flow rate of the medium density polyethylene in the inner layer at 190°C / 2.16 kg is 0.7-2.0 g / 10 min, preferably 0.8-1.0 g / 10 min, more preferably 0.9 g / 10 min.

[0029] Further, the elongation at break of the medium density polyethylene in the inner layer is ≥ 350%, preferably ≥ 400%.

[0030] Further, the melt flow rate of the linear low density polyethylene in the inner layer at 190°C / 2.16 kg is 1.0-2.5 g / 10 min, preferably 1.5-2.0 g / 10 min.

[0031] Further, the density of the high density polyethylene in the inner layer is 0.94-0.97 g / cm 3The melt flow rate at 190°C / 2.16 kg is ≤ 1.3 g / 10 min, preferably 0.9-1.2 g / 10 min.

[0032] In a preferred embodiment, the raw materials for the inner layer comprise, by total mass: 8-15% low density polyethylene, 55-65% medium density polyethylene, 18-22% linear low density polyethylene and 8-12% high density polyethylene.

[0033] Further, the raw materials for the middle layer comprise, by total mass: 15-45% low density polyethylene and 55-85% linear low density polyethylene.

[0034] Further, the raw materials for the middle layer comprise, by total mass: 20-35% low density polyethylene and 65-80% linear low density polyethylene.

[0035] Preferably, the low density polyethylene of the middle layer has a melt flow rate at 190°C / 2.16 kg of 1.5-3.0 g / 10 min.

[0036] Further, the linear low density polyethylene of the middle layer has a melt flow index at 190°C / 2.16 kg of 0.6-1.8 g / 10 min, preferably 1-1.5 g / 10 min.

[0037] Further, the linear low density polyethylene of the middle layer has a tensile strength at break in the vertical direction of ≥ 30 MPa, preferably 35-50 MPa.

[0038] Further, the raw materials for the outer layer are 100% low density polyethylene.

[0039] The application controls the PE film to be a three-layer structure and strictly stipulates the type and amount of each layer of raw materials, can further improve the heat sealing performance of the packaging film by improving the temperature resistance of the PE film, realize the wide sealing edge, three-dimensional structure and load bearing of the bubble bag. LDPE has super short and long branches, low crystallinity and melt viscosity, good flowability during processing, and is prone to cause processing difficulties, quality problems such as lines, water marks and folding of the PE film when the addition amount is too low, but it is not resistant to high temperature. Compared with LDPE, LLDPE does not have long branches in its structure, has high crystallinity, which is beneficial to improve the melting point and tensile strength and tear resistance of the PE film, but its addition will cause the problem of increasing the surface roughness of the PE film, and the use of a certain amount of LDPE can improve the problem. The crystallinity of HDPE is higher, which can significantly improve the high temperature resistance of the PE film, but the molecular weight and melt flow rate are too high, the processing dispersion is very poor, which is easy to cause uneven dispersion of the system, and a certain amount of MDPE and LDPE can improve the above problems. The relative amount of LDPE, LLDPE, MDPE and HDPE is optimized and the melt index or melt flow rate (equivalent to indirectly controlling the molecular weight and molecular weight distribution), tensile strength, elongation rate and other parameters are strictly stipulated, so that the prepared PE film has excellent high temperature resistance and heat sealing performance, tensile and tear resistance.

[0040] Preferably, the low-density polyethylene in the outer layer is consistent with the low-density polyethylene of the middle layer.

[0041] Further, the preparation method of the PE film is: uniformly mixing the raw materials of the inner layer, the middle layer and the outer layer, adjusting the screw temperature of the three layers to 130-165℃, and co-extruding and blowing the three layers into a PE film.

[0042] Further, the screw temperature of the three layers is 140-160℃.

[0043] Further, the preparation method of the self-adhesive composite film is: compounding the inner layer of the printed temperature-resistant layer and the stable buffer layer by hot pressing and bonding to obtain a composite film, and then compounding the composite film and the high-efficiency buffer layer by hot lamination.

[0044] Further, the temperature of the hot pressing and bonding is 100-140℃, and the bonding speed is ≤15m / min.

[0045] Further, the temperature of the hot lamination is 100-140℃.

[0046] Secondly, the application also provides a three-dimensional buffer bubble bag made of the self-adhesive composite film.

[0047] Further, the structure of the three-dimensional buffer bubble bag from the inside to the outside is: high-efficiency buffer layer, stable buffer layer and printed temperature-resistant layer.

[0048] Further, the edge sealing width of the three-dimensional cushioning bubble bag is 0.5-1.5 cm, preferably 1-1.5 cm.

[0049] Advantages

[0050] 1、The present application composites high-efficiency cushioning layer, stable cushioning layer and printed temperature-resistant layer, which can realize the compression resistance and high-temperature resistance of the composite film; further optimizing the grammage or density of the high-efficiency cushioning layer and the stable cushioning layer indirectly controls the size and density of the foaming volume, which can make the compression resistance of the composite film more excellent;

[0051] 2、The present application optimizes the printed temperature-resistant layer to be PE film, and specifies the types and amounts of raw materials of the three-layer structure of the PE film, improves the high-temperature resistance of the PE film, improves the heat bonding temperature and bonding effect of the composite film, realizes the three-dimensional structure and practicality of the bubble bag prepared by the composite film;

[0052] 3、The bubble bag of the present application has a three-layer composite structure, has a self-adhesive seal, a three-dimensional flat bottom structure and a wide edge sealing, and has good load-bearing effect (without damage) and protection effect on the contents carried. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figures 1-3 : The physical map of the three-dimensional cushioning bubble bag of the present application;

[0054] Figure 4 : The anti-shock cushioning test diagram of the bubble bag of Example 1 of the present application. DETAILED DESCRIPTION

[0055] EMBODIMENT

[0056] Example 1

[0057] The present embodiment provides a self-adhesive composite film; the self-adhesive composite film comprises the following three layers in sequence: a high-efficiency cushioning layer with a thickness of 3 mm, a stable cushioning layer with a thickness of 0.5 mm, and a printed temperature-resistant layer with a thickness of 0.03 mm.

[0058] The high-efficiency cushioning layer is a polyethylene bubble film with a grammage of 60 g / m 2 .

[0059] The stable cushioning layer is a pearl cotton film, the raw material of the pearl cotton film is polyethylene, and the density of the pearl cotton film is 20 kg / m 3 .

[0060] The printed temperature-resistant layer is a PE film, which comprises an inner layer, a middle layer and an outer layer, and the thicknesses of the three layers are equal.

[0061] The raw materials for preparing the inner layer include 10% low-density polyethylene, 60% medium-density polyethylene, 20% linear low-density polyethylene and 10% high-density polyethylene, by total mass.

[0062] The low-density polyethylene in the inner layer has a melt flow rate of 1.7-2.2 g / 10 min at 190℃ / 2.16 kg, and a brand of LDPE2426. The medium-density polyethylene has a melt flow rate of 0.9 g / 10 min at 190℃ / 2.16 kg, and a breaking elongation ≥400%, and a brand of MDPE3410. The linear low-density polyethylene has a melt flow rate of 1.8 g / 10 min at 190℃ / 2.16 kg, and a brand of LLDPE7042. The high-density polyethylene has a melt flow rate of 1.0 g / 10 min at 190℃ / 2.16 kg, and a brand of HDPE5000s.

[0063] The raw materials for preparing the middle layer include 30% low-density polyethylene and 70% linear low-density polyethylene, by total mass. The low-density polyethylene has a melt flow rate of 1.7-2.2 g / 10 min at 190℃ / 2.16 kg, and a brand of LDPE2426. The linear low-density polyethylene has a melt index of 1 g / 10 min at 190℃ / 2.16 kg, and a breaking tensile strength of 40.6 MPa, and a brand of LLDPE2045G.

[0064] The raw materials for preparing the outer layer include 100% low-density polyethylene, and a brand of LDPE2426.

[0065] The method for preparing the PE film includes mixing the raw materials for the inner layer, the middle layer and the outer layer respectively, adjusting the screw temperature of the three layers to 150℃, and co-extruding and blowing the three layers into a PE film.

[0066] The method for preparing the self-adhesive composite film includes: compositing the inner layer of the printed temperature-resistant layer and the stable buffer layer through hot pressing (temperature of 130℃, bonding speed of 10 m / min) to obtain a composite film, and then compositing the composite film and the high-efficiency buffer layer through hot bonding (temperature of 130℃).

[0067] The embodiment also provides a three-dimensional buffer bubble bag made of the self-adhesive composite film, and the three-dimensional buffer bubble bag has an inner-to-outer structure of the high-efficiency buffer layer, the stable buffer layer and the printed temperature-resistant layer, and an edge sealing width of 1 cm.

[0068] Example 2

[0069] The embodiment provides a self-adhesive composite film, which includes the following three layers in sequence: a high-efficiency buffer layer with a thickness of 5 mm, a stable buffer layer with a thickness of 0.3 mm, and a printed temperature-resistant layer with a thickness of 0.2 mm.

[0070] The high-efficiency buffer layer is a polyethylene bubble film with a grammage of 50 g / m 2 .

[0071] The stable buffer layer is a pearl wool film, the raw material of which is polyethylene, and the density of the pearl wool film is 25 kg / m 3 .

[0072] The printed temperature-resistant layer is a PE film, which comprises an inner layer, a middle layer and an outer layer; the thicknesses of the three layers are equal.

[0073] According to the total mass, the raw material of the inner layer comprises 15% low-density polyethylene, 55% medium-density polyethylene, 18% linear low-density polyethylene and 12% high-density polyethylene.

[0074] In the inner layer, the melt flow rate of the low-density polyethylene at 190℃ / 2.16kg is 1.7-2.2 g / 10min, and the grade is LDPE2426. The melt flow rate of the medium-density polyethylene at 190℃ / 2.16kg is 0.9 g / 10min, the elongation at break is ≥400%, and the grade is MDPE3410. The melt flow rate of the linear low-density polyethylene at 190℃ / 2.16kg is 1.8 g / 10min, and the grade is LLDPE7042. The melt flow rate of the high-density polyethylene at 190℃ / 2.16kg is 1.0 g / 10min, and the grade is HDPE5000s.

[0075] According to the total mass, the raw material of the middle layer comprises 20% low-density polyethylene and 80% linear low-density polyethylene. The melt flow rate of the low-density polyethylene at 190℃ / 2.16kg is 1.7-2.2 g / 10min, and the grade is LDPE2426. The melt flow index of the linear low-density polyethylene at 190℃ / 2.16kg is 1 g / 10min, and the tensile strength at break is 40.6 MPa, and the grade is LLDPE2045G.

[0076] The raw material of the outer layer is 100% low-density polyethylene, and the grade is LDPE2426.

[0077] The preparation method of the PE film is that the raw materials of the inner layer, the middle layer and the outer layer are mixed uniformly respectively, the screw temperature of the three layers is adjusted to 140℃, and the three layers are co-extruded and blown into a PE film.

[0078] The preparation method of the self-adhesive composite film is that the inner layer of the printed temperature-resistant layer and the stable buffer layer are compounded by hot pressing (the temperature is 100℃, and the bonding speed is 12 m / min) to obtain a composite film, and then the composite film and the high-efficiency buffer layer are compounded by hot lamination (the temperature is 100℃).

[0079] The embodiment also provides a three-dimensional cushion bubble bag made of the self-adhesive composite film, which has, from inside to outside, a high-efficiency cushion layer, a stable cushion layer and a printed temperature-resistant layer; and the edge sealing width is 1 cm.

[0080] Embodiment 3

[0081] The embodiment provides a self-adhesive composite film, which comprises, in sequence, three layers of structures: a high-efficiency cushion layer with a thickness of 2 mm, a stable cushion layer with a thickness of 2 mm, and a printed temperature-resistant layer with a thickness of 0.02 mm.

[0082] The high-efficiency cushion layer is a polyethylene bubble film with a grammage of 70 g / m 2 .

[0083] The stable cushion layer is a pearl wool film, and the pearl wool film is prepared from polyethylene, and has a density of 15 kg / m 3 .

[0084] The printed temperature-resistant layer is a PE film, which comprises an inner layer, a middle layer and an outer layer, and the three layers have equal thicknesses.

[0085] According to the total mass, the inner layer is prepared from 8% low-density polyethylene, 62% medium-density polyethylene, 22% linear low-density polyethylene and 8% high-density polyethylene.

[0086] In the inner layer, the low-density polyethylene has a melt flow rate of 1.7-2.2 g / 10 min at 190 ℃ / 2.16 kg, and has a brand of LDPE2426. The medium-density polyethylene has a melt flow rate of 0.9 g / 10 min at 190 ℃ / 2.16 kg, and has an elongation at break of ≥400%, and has a brand of MDPE3410. The linear low-density polyethylene has a melt flow rate of 1.8 g / 10 min at 190 ℃ / 2.16 kg, and has a brand of LLDPE7042. The high-density polyethylene has a melt flow rate of 1.0 g / 10 min at 190 ℃ / 2.16 kg, and has a brand of HDPE5000s.

[0087] According to the total mass, the middle layer is prepared from 35% low-density polyethylene and 65% linear low-density polyethylene. The low-density polyethylene has a melt flow rate of 1.7-2.2 g / 10 min at 190 ℃ / 2.16 kg, and has a brand of LDPE2426. The linear low-density polyethylene has a melt index of 1 g / 10 min at 190 ℃ / 2.16 kg, and has a tensile strength at break of 40.6 MPa, and has a brand of LLDPE2045G.

[0088] The preparation raw material of the outer layer is 100% low-density polyethylene with a brand of LDPE2426.

[0089] The preparation method of the PE film is: uniformly mixing the raw materials of the inner layer, the middle layer and the outer layer, adjusting the screw temperature of the three layers to 160°C, and co-extrusion blowing the three layers into a PE film.

[0090] The preparation method of the self-adhesive composite film is: compounding the inner layer of the printed temperature-resistant layer and the stable buffer layer by hot pressing (temperature is 140°C, and the bonding speed is 15 m / min) to obtain a composite film, and then compounding the composite film and the high-efficiency buffer layer by hot lamination (temperature is 140°C).

[0091] The embodiment also provides a three-dimensional buffer bubble bag made of the self-adhesive composite film, and the three-dimensional buffer bubble bag has an inner-to-outer structure of a high-efficiency buffer layer, a stable buffer layer and a printed temperature-resistant layer; and the edge sealing width is 1 cm.

[0092] Comparative Example 1

[0093] The embodiment is basically identical with Example 1, except that the preparation raw material of the inner layer includes 70% low-density polyethylene, 20% linear low-density polyethylene and 10% high-density polyethylene according to the total mass.

[0094] Comparative Example 2

[0095] The embodiment is basically identical with Example 1, except that the preparation raw material of the inner layer includes 5% low-density polyethylene, 35% medium-density polyethylene, 40% linear low-density polyethylene and 20% high-density polyethylene according to the total mass.

[0096] Comparative Example 3

[0097] The embodiment is basically identical with Example 1, except that the gram weight of the bubble film is 30 g / m 2 , and the density of the pearl wool film is 12 kg / m 3 .

[0098] Comparative Example 4

[0099] The embodiment is basically identical with Example 1, except that the printed temperature-resistant layer is a PE film which includes an inner layer and an outer layer.

[0100] Comparative Example 5

[0101] The embodiment is basically identical with Example 1, except that POE is used to replace high-density polyethylene in the inner layer of the PE film, and the brand of the POE is POE 1881G.

[0102] Comparative Example 6

[0103] The comparative example provides a conventional heat preservation bag product, which is produced by Suzhou Zhifei Packaging Material Co., Ltd.

[0104] Comparative Example 7

[0105] The comparative example provides a conventional bubble bag product, which is a two-side sealing and envelope type structure, and is produced by Suzhou Zhifei Packaging Material Co., Ltd.

[0106] Performance test method:

[0107] 1. Anti-shock buffering performance: drop test, the same specification glass bottles (without filling) are placed in the bubble bag, and the bubble bag is dropped along the direction perpendicular to the ground, and the distance between the bubble bag and the ground when the glass breaks is tested; the longer the distance, the better the anti-shock buffering performance of the bubble bag. Among them, the glass bottles loaded in the bubble bag of Example 1 were not broken when the distance from the ground was 10, 25, 50 cm ( Figure 4 left), and the glass bottles were broken when the distance from the ground was 75 cm ( Figure 4 right).

[0108] 2. Compression test: a 10kg weight is applied to the bubble bag, and the single-side bag body thickness of the bubble bag is measured within different test times (0h, 0.5h, 1h, 3h). Among them, the test results of Example 1: 0h thickness is 4.1mm, 0.5h thickness is 3.84-3.96mm, 1h thickness is 3.74mm, and 3h thickness is 3.47mm. The change amount of the thickness is very small, which indicates that the bubble bag has good compression resistance.

[0109] 3. Heat sealing strength: GBL-L electronic tensile testing machine.

[0110] Performance test results:

[0111] The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114]

Claims

1. A self-adhesive composite film, characterized by, The self-adhesive composite film comprises a laminated three-layer structure in sequence: a high-efficiency buffer layer with a thickness of 1-10 mm, a stable buffer layer with a thickness of 0.1-4 mm, and a printed temperature-resistant layer with a thickness of 0.005-1 mm. The high-efficiency buffer layer is a bubble film, the gram weight of the bubble film is 40-80 g / m 2 ; the stable buffer layer is a pearl wool film; the density of the pearl wool film is 15-25 kg / m 3 ; The printed temperature-resistant layer is a PE film comprising an inner layer, a middle layer and an outer layer, and the preparation raw materials of the inner layer comprise, according to the total mass: 5-25% low-density polyethylene, 40-80% medium-density polyethylene, 10-30% linear low-density polyethylene and 3-15% high-density polyethylene. The preparation raw materials of the middle layer comprise 15-45% low-density polyethylene and 55-85% linear low-density polyethylene; and the preparation raw materials of the outer layer are 100% low-density polyethylene.

2. The self-adhesive composite film according to claim 1, characterized in that, The melt flow rate of the low-density polyethylene in the inner layer at 190℃ / 2.16kg is 1.0-4.0g / 10min, the melt flow rate of the medium-density polyethylene at 190℃ / 2.16kg is 0.7-2.0g / 10min, the melt flow rate of the linear low-density polyethylene at 190℃ / 2.16kg is 1.0-2.5g / 10min, and the melt flow rate of the high-density polyethylene at 190℃ / 2.16kg is ≤1.3g / 10min.

3. The self-adhesive composite film according to claim 1, wherein The melt flow rate of the low-density polyethylene in the inner layer at 190℃ / 2.16kg is 1.7-2.2g / 10min, the melt flow rate of the medium-density polyethylene at 190℃ / 2.16kg is 0.8-1.0g / 10min, the melt flow rate of the linear low-density polyethylene at 190℃ / 2.16kg is 1.5-2.0g / 10min, and the melt flow rate of the high-density polyethylene at 190℃ / 2.16kg is 0.9-1.2g / 10min.

4. The self-adhesive composite film according to claim 1, wherein The preparation raw materials of the inner layer comprise, according to the total mass: 8-15% low-density polyethylene, 55-65% medium-density polyethylene, 18-22% linear low-density polyethylene and 8-12% high-density polyethylene.

5. The three-dimensional cushioning bubble bag made of the self-adhesive composite film according to any one of claims 1-4, characterized in that, The three-dimensional buffer bubble bag comprises, from inside to outside: a high-efficiency buffer layer, a stable buffer layer and a printed temperature-resistant layer.

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