A packaging bag laminate

Abstract

This application relates to the technical field of electronic device packaging materials, and specifically discloses a packaging bag laminate. The packaging bag laminate sequentially includes a polyurethane outer layer, a polyurethane aluminized composite layer, and a PE composite layer from outside to inside. The polyurethane aluminized composite layer includes a polyurethane inner layer and a vacuum aluminized film, wherein the vacuum aluminized film is connected to the polyurethane outer layer, and both the polyurethane outer layer and the polyurethane inner layer are biodegradable; a plurality of through holes penetrating through to the polyurethane inner layer are formed in the PE composite layer. When the packaging bag laminate of this application undergoes microbial degradation, both the polyurethane outer layer and the polyurethane inner layer can be degraded, which helps to recycle the aluminized film, and the packaging bag laminate has an environmental protection effect, which can avoid environmental pollution caused by aluminum heavy metal substances.

Description

Technical Field

[0001] This application belongs to the technical field of electronic device packaging materials, and more specifically, relates to a packaging bag laminate. Background Art

[0002] Plastic packaging bags are commonly used packaging and containment materials in life. For a long time, the white pollution problem of plastic products has had a significant impact on the environment. For the packaging bags of electronic devices, they often contain metal-coated layers, such as aluminum-coated and silver-coated layers, etc. The function of these metal-coated layers is to insulate heat, block light, and reflect external light to protect the internal electronic devices.

[0003] In the related art, the provided packaging bags are generally co-extruded and blow-molded from different layers of plastic films, and then supplemented with metal-coated films and covered with protective layers. This metal film is often located in the middle layer of the packaging bag. After the packaging bag is used up, it is often directly thrown away, and at the same time, the metal aluminum film is also thrown away with the packaging bag, which will cause metal pollution to the environment. Therefore, it is necessary to produce an environmentally friendly packaging bag. Summary of the Invention

[0004] In order to solve the problem that the direct throwing away of the packaging bag with an aluminum film after use will cause metal pollution, this application provides a packaging bag laminate.

[0005] This application provides a packaging bag laminate, adopting the following technical solutions:

[0006] A packaging bag laminate, which sequentially includes a polyurethane outer layer, a polyurethane aluminum-coated composite layer, and a PE composite layer from outside to inside. The polyurethane aluminum-coated composite layer includes a polyurethane inner layer and a vacuum aluminum-coated film. Among them, the vacuum aluminum-coated film is connected to the polyurethane outer layer, and both the polyurethane outer layer and the polyurethane inner layer are biodegradable;

[0007] A plurality of through holes penetrating through to the polyurethane inner layer are formed in the PE composite layer.

[0008] By adopting the above technical solutions, the polyurethane outer layer and the polyurethane inner layer have good oil resistance, wear resistance, low temperature resistance, aging resistance, heat insulation, and corrosion resistance, and have a protective effect on the packaged electronic devices. The polyurethane aluminum-coated composite layer includes a vacuum aluminum-coated film, and the vacuum aluminum-coated film is connected to the polyurethane outer layer. Utilizing the optical property of aluminum with a high reflectivity and being able to strongly reflect light, the polyurethane aluminum-coated composite layer has heat insulation and reflection effects. The PE composite layer has an anti-corrosion and smooth surface effect, so that the protected electronic products are not polluted and scratched by the outside during transportation, storage, and use, and thus protect the original smooth and shiny surface of the electronic products. The packaging bag laminate composed of the polyurethane outer layer, the polyurethane inner layer, the polyurethane aluminum-coated composite layer, and the PE composite layer has functions such as light shielding, leak prevention, shielding, flame retardancy, insulation, and protection for electronic products when storing electronic products.

[0009] The polyurethane aluminized composite layer includes a polyurethane inner layer and a vacuum aluminized film, and the vacuum aluminized film is connected to the polyurethane outer layer. A plurality of through holes penetrating through to the polyurethane inner layer are formed in the PE composite layer. When the packaging bag laminate undergoes microbial degradation, the polyurethane outer layer degrades. At the same time, microorganisms pass through the through holes in the PE composite layer and come into contact with the polyurethane inner layer, promoting the degradation of the polyurethane inner layer. At this time, the vacuum aluminized film can be very easily separated from the PE composite layer, and the polyurethane outer layer and the polyurethane inner layer are gradually degraded, thereby contributing to the recovery of aluminum, and the packaging bag laminate has an environmental protection effect, and pollution of the environment by heavy metal substances such as aluminum is avoided as much as possible.

[0010] Preferably, the thickness of the polyurethane outer layer is 10 - 15 μm, the thickness of the polyurethane aluminized composite layer is 13 - 17 μm, and the thickness of the PE composite layer is 180 - 200 μm.

[0011] By adopting the above technical solution, the thickness settings of the polyurethane outer layer, the polyurethane aluminized composite layer, and the PE composite layer ensure that the packaging bag laminate has good mechanical strength, heat insulation, and heat preservation effects.

[0012] Preferably, the PE composite layer includes five PE film layers, namely layer A, layer B, layer C, layer D, and layer E. The thickness percentages of layer A, layer B, layer C, layer D, and layer E are (13% - 17%): (13% - 17%): (38% - 42%): (13% - 17%): (13% - 17%).

[0013] By adopting the above technical solution, the PE composite layer includes five PE film layers, ensuring the mechanical strength, heat insulation, and insulation of the PE composite layer. The five PE film layers with different thicknesses can reduce the light transmittance of the PE composite layer, thereby increasing the number of light refractions of the PE composite layer and reducing the light transmittance, so as to have protective effects such as light shielding and insulation on the electronic products stored inside.

[0014] Preferably, by weight percentage, each of the five PE film layers is made of 25 - 35% of low - density polyethylene, 45 - 55% of linear low - density polyethylene, and 15 - 25% of metallocene linear low - density polyethylene based on the total weight of the PE film layer.

[0015] By adopting the above technical solution, metallocene linear low - density polyethylene has high mechanical strength and good toughness, but high transparency, high cost, and is not soft enough; low - density polyethylene has low cost and low light transmittance, but poor mechanical strength; linear low - density polyethylene has properties between the two. Using three different types of polyethylene in combination can simultaneously combine the mechanical advantages of different resin plastics to obtain a PE film with comprehensive properties.

[0016] Preferably, the polyurethane inner layer is made of the following raw materials: modified acetate denatured starch, polytetrahydrofuran ether diol, polyether triol, isophorone diisocyanate, aloe gel, 1,4-butanediol, methyl ethyl ketone, triethylamine, deionized water, silicone and dibutyltin dilaurate.

[0017] By adopting the above technical solution, part of the -OH in the modified acetate denatured starch reacts with the -NCO in the isophorone diisocyanate to carry out grafting of polymer groups, increasing the chain length of the modified acetate denatured starch. Part of the -OH in the polytetrahydrofuran ether diol and polyether triol reacts with the -NCO in the isophorone diisocyanate to carry out grafting. At the same time, the remaining hydroxyl groups in the modified acetate denatured starch, polytetrahydrofuran ether diol and polyether triol initiate the ring-opening polymerization reaction of caprolactone to form a ternary graft copolymer, and then form a crosslinked framework structure, further increasing the chain length and side chains of the modified acetate denatured starch, and thus ensuring the compatibility, film-forming property and dispersibility of the product.

[0018] Dibutyltin dilaurate is used as a catalyst to further accelerate the reaction rate of the modified acetate denatured starch. 1,4-butanediol is used as a chain extender to further increase the molecular chain length of the modified acetate denatured starch, so that the modified acetate denatured starch has good film-forming property. Aloe gel is used as a plasticizer, stabilizer and binder for the degradable material, so that the modified acetate denatured starch can form a film better, and the prepared polyurethane inner layer has good tensile strength, elongation at break, degradability and environmental protection performance. Therefore, the prepared packaging layers of various specifications are not easy to break when stretched, have good flexibility, and methyl ethyl ketone as a solvent greatly reduces the viscosity of the system. Triethylamine is used as a salt-forming agent to neutralize the carboxylic acid groups to emulsify the silicone in water, which helps to form an emulsion.

[0019] In addition, aloe gel contains more water. During microbial degradation, it provides the environmental humidity required for degradation for microorganisms and accelerates the degradation rate of the polyurethane inner layer. Aloe gel also contains amino acids and complex polysaccharide substances, which improve the hydrophilic property and degradation rate of the polyurethane inner layer. 1,4-butanediol as a chain extender not only increases the chain length of the modified acetate denatured starch, but also accelerates the decomposition rate of the modified acetate denatured starch during the microbial degradation process. Cooperating with aloe gel, it further improves the degradation rate of the polyurethane inner layer.

[0020] Preferably, the preparation method of the modified acetate denatured starch includes the following steps:

[0021] S1. Prepare a saturated starch aqueous solution of oxidized hydroxypropyl starch at a temperature of 20-30 °C;

[0022] S2. Adjust the pH value of the saturated starch aqueous solution prepared in S1 to 9.5 - 10 using sodium bicarbonate;

[0023] S3. Gradually add the acetic anhydride solution to the solution prepared in S2. The mass ratio of acetic anhydride to starch is 12:15 - 10, the reaction temperature is 70 - 90 °C, the reaction time is 2 - 3.5 h, then add wood cellulose and continue to react for 1 - 2 h. Finally, cool down, filter and wash to obtain the modified acetate modified starch.

[0024] By adopting the above technical solution, the oxidized hydroxypropyl starch is modified using the acetic anhydride solution. The prepared starch has good hydrophobicity and stability. At the same time, the prepared modified acetate modified starch has good dispersibility, enabling the modified acetate modified starch to react well with isophorone diisocyanate, further enhancing the mechanical properties, antibacterial properties and degradation properties of the polyurethane inner layer. At the same time, wood cellulose is added. Wood cellulose has a small specific gravity, a large specific surface area, and is an organic flocculent fiber material with excellent stability. The combination of wood cellulose and the acetic anhydride solution further improves the adhesiveness of the oxidized hydroxypropyl starch, thereby improving the film-forming property and degradation property of the polyurethane inner layer, and greatly reducing environmental pollution;

[0025] In addition, the modified acetate modified starch added with lignin fiber reduces the glass transition temperature T g of the polyurethane inner layer during the subsequent degradation process, increases the degree of microphase separation, and promotes the degradation of the polyurethane inner layer.

[0026] Preferably, the raw material of the polyurethane outer layer is castor oil-based polyurethane, and the castor oil-based polyurethane is made from castor oil, polytetrahydrofuran ether glycol, isophorone diisocyanate, dibutyltin dilaurate, triethylamine, deionized water and 1,2,3-butanetriol.

[0027] By adopting the above technical solution, castor oil has unique cross-linking characteristics. The -OH in castor oil and polytetrahydrofuran ether glycol grafts with the -NCO in isophorone diisocyanate to synthesize a macromolecular polymer with a small number of branched chains. The addition of dibutyltin dilaurate accelerates the grafting rate of castor oil, polytetrahydrofuran ether glycol and isophorone diisocyanate. 1,2,3-butanetriol is used as a chain extender to further increase the chain length of castor oil, thereby ensuring the compatibility and film-forming property of the castor oil-based polyurethane; triethylamine is used as a salt-forming agent to neutralize the carboxylic acid group and emulsify the silicone in water, which helps to form an emulsion.

[0028] During the degradation process of microorganisms, the outer polyurethane layer can be rapidly degraded. However, the degradation rate of the outer polyurethane layer is much lower than that of the inner polyurethane layer. The inner polyurethane layer degrades first, causing the aluminized polyurethane composite layer to separate from the PE composite layer first. Then, with the degradation of the outer polyurethane layer, it helps to recover the vacuum aluminized film. Moreover, the degradation of the outer and inner polyurethane layers does not cause soil pollution and can be used as a slow-release material, capable of maintaining the controlled-release ability of fertilizers in a short period of time.

[0029] Preferably, the thickness of the vacuum aluminized film is 380 - 600 angstroms.

[0030] By adopting the above technical solution, an aluminized film with a thickness of 380 - 600 angstroms can ensure its sufficient light impermeability, reflectivity, and heat insulation, and there is enough margin for it to be polished smooth.

[0031] Preferably, the diameter of the through-hole is 0.5 - 2 mm.

[0032] Preferably, there are 1 - 10 through-holes per square centimeter in the PE composite layer.

[0033] In summary, the present application has the following beneficial effects:

[0034] 1. When the packaging bag laminate undergoes microbial degradation in the present application, the outer polyurethane layer degrades. At the same time, microorganisms pass through the through-holes in the PE composite layer and contact the inner polyurethane layer, promoting the degradation of the inner polyurethane layer. At this time, the vacuum aluminized film can be very easily separated from the PE composite layer, and the outer and inner polyurethane layers can gradually degrade, thereby helping to recover aluminum, and the packaging bag laminate has an environmental protection effect, which can avoid the pollution of the environment by aluminum heavy metal substances.

[0035] 2. The aluminized polyurethane composite layer of the present application includes a vacuum aluminized film, and the vacuum aluminized film is connected to the outer polyurethane layer. Utilizing the optical property of aluminum with a high reflectivity and being able to strongly reflect light, the aluminized polyurethane composite layer has heat insulation and reflection functions. The PE composite layer has anti-corrosion and smooth surface functions, so that the protected electronic products are not polluted or scratched from the outside during transportation, storage, and use, thereby protecting the original smooth and shiny surface of the electronic products. The packaging bag laminate composed of the outer polyurethane layer, the inner polyurethane layer, the aluminized polyurethane composite layer, and the PE composite layer has functions such as light shielding, leak prevention, shielding, flame retardancy, insulation, and protection for storing electronic products.

[0036] 3. The PE composite layer of the present application comprises five PE film layers, ensuring the mechanical strength, heat insulation and insulation of the PE composite layer. The five PE film layers with different thicknesses can reduce the light transmittance of the PE composite layer, thereby increasing the number of light refractions of the PE composite layer and reducing the light transmittance, so as to provide protection such as light shielding and insulation for the electronic products stored inside. Detailed implementation manners

[0037] The present application will be further described in detail below in conjunction with embodiments.

[0038] The raw materials used in the examples and preparation examples can be obtained commercially.

[0039] Preparation example of the composite layer

[0040] Preparation example 1-1

[0041] The PE composite layer comprises five PE film layers, namely layer A, layer B, layer C, layer D and layer E. The thickness percentages of the layer A, layer B, layer C, layer D and layer E are 15%:15%:40%:15%:15%; the thickness of the PE composite layer is 190 μm.

[0042] Among them, by weight percentage, each of the five PE film layers is made of 30 kg of low-density polyethylene, 50 kg of linear low-density polyethylene, and 20 kg of metallocene linear low-density polyethylene.

[0043] Specifically, the preparation method of the five PE film layers includes the following steps:

[0044] Melting and plasticizing low-density polyethylene, linear low-density polyethylene, and metallocene linear low-density polyethylene at a temperature of 160 °C for 2 h to form melt I, and then melt II, melt III, melt IV, and melt V are all prepared by the above method;

[0045] Form billets from melt I, melt II, melt III, melt IV, and melt V at an extrusion speed of 1.2 m / s respectively, fix the billets in a prefabricated mold to obtain a parison; perform extrusion blow molding on the parison under a gas pressure of 1.5 MPa, control the blow-up ratio to be 2:1 and the length-diameter ratio to be 35:1, and use cooling water at 10 °C for cooling and solidification operation at a flow rate of 30 L / min to obtain a primary product; stretch the primary product through a screw roller device, control the draw ratio to be 2, and perform winding and packaging operations to obtain a five-layer coextrusion blow-molded PE composite film.

[0046] Preparation example 1-2

[0047] The difference from Preparation Example 1-1 is that the thickness percentages of the A layer, B layer, C layer, D layer and E layer are 13%:17%:42%:13%:15%; the thickness of the PE composite layer is 180 μm.

[0048] Preparation Example 1-3

[0049] The difference from Preparation Example 1-1 is that the thickness percentages of the A layer, B layer, C layer, D layer and E layer are 17%:15%:38%:17%:13%; the thickness of the PE composite layer is 200 μm.

[0050] Preparation Example 1-4

[0051] The difference from Preparation Example 1-1 is that the five-layer PE film layer is all made of 25 kg of low-density polyethylene, 45 kg of linear low-density polyethylene, and 30 kg of metallocene linear low-density polyethylene.

[0052] Preparation Example 1-5

[0053] The difference from Preparation Example 1-1 is that the five-layer PE film layer is all made of 35 kg of low-density polyethylene, 55 kg of linear low-density polyethylene, and 10 kg of metallocene linear low-density polyethylene.

[0054] Preparation Example 1-6

[0055] The difference from Preparation Example 1-1 is that the PE composite layer is composed of a single-layer PE film, and the thickness of the PE composite layer is 190 μm.

[0056] Preparation Example of Polyurethane Inner Layer

[0057] Preparation Example 2-1

[0058] The polyurethane inner layer is made of the following raw materials by weight: 40 kg of modified acetate-modified starch, 25 kg of polytetrahydrofuran ether glycol, 12 kg of polyether triol, 90 kg of isophorone diisocyanate, 15 kg of aloe gel, 6 kg of 1,4-butanediol, 80 kg of methyl ethyl ketone, 20 kg of triethylamine, 100 kg of deionized water, 3 kg of silicone, and 2 kg of dibutyltin dilaurate.

[0059] Specifically, the preparation method of the polyurethane inner layer includes the following steps:

[0060] Mix isophorone diisocyanate, polytetrahydrofuran glycol, polyether triol, and methyl ethyl ketone, keep the temperature at 75 °C for 2 h, then raise the temperature to 80 °C, add modified acetate modified starch, aloe gel, 1,4-butanediol, and dibutyltin dilaurate, keep the temperature for reaction for 3 h, after cooling to room temperature, add triethylamine under high-speed stirring, emulsify with deionized water, and remove methyl ethyl ketone by vacuum distillation to obtain degradable polyurethane; then add silicone and mix evenly, coat to form a film to obtain the polyurethane inner layer.

[0061] Among them, the preparation method of the modified acetate modified starch includes the following steps:

[0062] S1. Prepare a saturated starch aqueous solution of 10 kg of oxidized hydroxypropyl starch at a temperature of 25 °C;

[0063] S2. Adjust the pH value of the saturated starch aqueous solution prepared in S1 to 9.5 - 10 with a sodium bicarbonate solution with a mass fraction of 8%;

[0064] S3. Gradually drop 10 kg of acetic anhydride solution into the solution prepared in S2, the mass ratio of acetic anhydride to starch is 12:13, the reaction temperature is 80 °C, the reaction time is 3 h, then add 15 kg of lignocellulose, continue the reaction for 1.5 h, and finally cool down, filter, and wash to obtain the modified acetate modified starch.

[0065] Preparation Example 2-2

[0066] The difference from Preparation Example 2-1 is that in the raw materials of the polyurethane inner layer, an equal amount of acetate modified starch is used to replace the modified acetate modified starch.

[0067] Preparation Example 2-3

[0068] The difference from Preparation Example 2-1 is that in the raw materials of the polyurethane inner layer, an equal amount of modified acetate modified starch is used to replace polytetrahydrofuran glycol.

[0069] Preparation Example 2-4

[0070] The difference from Preparation Example 2-1 is that in the raw materials of the polyurethane inner layer, an equal amount of modified acetate modified starch is used to replace polyether triol.

[0071] Preparation Example 2-5

[0072] The difference from Preparation Example 2-1 is that in the raw materials of the polyurethane inner layer, an equal amount of modified acetate modified starch is used to replace aloe gel.

[0073] Preparation Example 2-6

[0074] The difference from Preparation Example 2-1 is that in the preparation method of the modified acetate modified starch, lignocellulose is not added.

[0075] Preparation Examples 2-7

[0076] It is different from Preparation Example 2-1 in that the polyurethane inner layer is purchased from Chiyue Century (Guangdong) New Materials Co., Ltd. Examples

[0077] Example 1

[0078] A packaging bag laminate, which sequentially includes a polyurethane outer layer, a polyurethane aluminized composite layer, and a PE composite layer from outside to inside. The polyurethane aluminized composite layer includes a polyurethane inner layer and a vacuum aluminized film. The raw material of the polyurethane outer layer is castor oil-based polyurethane. Among them, the vacuum aluminized film is connected to the polyurethane layer; the castor oil-based polyurethane is made of 30 kg of castor oil, 10 kg of polytetrahydrofuran ether glycol, 25 kg of isophorone diisocyanate, 2 kg of dibutyltin dilaurate, 15 kg of triethylamine, 80 kg of deionized water, and 10 kg of 1,2,3-butanetriol; specifically, the preparation method of the castor oil-based polyurethane includes the following steps:

[0079] Mix the castor oil, polytetrahydrofuran ether glycol, and isophorone diisocyanate, keep it warm at 80°C for 3 h, then raise the temperature to 90°C, add dibutyltin dilaurate and 1,2,3-butanetriol, keep it warm and react for 2 h, cool it down to 50°C, add triethylamine under high-speed stirring, add deionized water and continue to stir for 1 h to obtain a castor oil-based polyurethane emulsion, and then coat and form a film to obtain a castor oil-based polyurethane layer.

[0080] The PE composite layer is prepared from Preparation Example 1-1; the polyurethane inner layer is prepared from Preparation Example 2-1.

[0081] There are 1-2 through holes with a diameter of 0.5 mm per square centimeter in the PE composite layer, which penetrate through to the polyurethane inner layer.

[0082] The thickness of the polyurethane outer layer is 12 μm, the thickness of the polyurethane aluminized composite layer is 15 μm, and the thickness of the vacuum aluminized film is 500 Å.

[0083] Example 2

[0084] It is different from Example 1 in that the thickness of the polyurethane outer layer is 10 μm, the thickness of the polyurethane aluminized composite layer is 13 μm, and the thickness of the vacuum aluminized film is 380 Å.

[0085] Example 3

[0086] It is different from Example 1 in that the thickness of the polyurethane outer layer is 15 μm, the thickness of the polyurethane aluminized composite layer is 17 μm, and the thickness of the vacuum aluminized film is 600 Å.

[0087] Example 4

[0088] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 1-2.

[0089] Example 5

[0090] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 1-3.

[0091] Example 6

[0092] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 1-4.

[0093] Example 7

[0094] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 1-5.

[0095] Example 8

[0096] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 1-6.

[0097] Example 9

[0098] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 2-2.

[0099] Example 10

[0100] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 2-3.

[0101] Example 11

[0102] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 2-4.

[0103] Example 12

[0104] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 2-5.

[0105] Example 13

[0106] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 2-6.

[0107] Example 14

[0108] The difference from Example 1 is that the PE composite layer is prepared from Preparation Example 2-7.

[0109] Comparative Example

[0110] Comparative Example 1

[0111] The difference from Example 1 is that both the polyurethane outer layer and the polyurethane inner layer are obtained by reacting polybutylene glycol, 4,4'-diphenylmethane diisocyanate with 1,4-butanediol as a chain extender in a spiral basic equipment. The soft segment concentration is 44.3%, and the hard segment concentration is 58.6%.

[0112] Comparative Example 2

[0113] The difference from Example 1 is that there are no through holes on the PE composite layer.

[0114] Performance detection test

[0115] The packaging bag laminates prepared in Examples 1-14 and Comparative Examples 1-2 were cut into standard test sizes, and the mechanical properties of the films, including tensile strength, impact strength and tear strength, were tested according to ASTM D882-2010.

[0116] Degradation performance test: The samples prepared in Examples 1-14 and Comparative Examples 1-2 were placed in moist soil at 37 °C, and the degradation mass loss rates of the test specimens after 20 d and 45 d were tested, referring to GB / T 20197-2006 "Definition, Classification, Labeling and Degradation Performance Requirements for Degradable Plastics".

[0117] Table 1

[0118]

[0119] It can be seen from Table 1 that the packaging bag laminates prepared in Examples 1-3 of the present application have better mechanical properties and degradation performance. Among them, the tensile strength of the packaging bag laminate prepared in Example 1 is 59.3 MPa, the tear strength is 98.5 KN / m, the mass loss rate after 20 d is 23.5%, the mass loss rate after 60 d is 89.1%, and the mass loss rate after 90 d is 98.5%.

[0120] In Examples 4-5, by changing the thickness of the PE composite layer and adjusting the thickness percentages between layers A, B, C, D and E, the mechanical properties of the packaging bag laminate decreased slightly, but the degradation performance remained unchanged. In Examples 6-7, by changing the contents of low-density polyethylene, linear low-density polyethylene and metallocene linear low-density polyethylene, the mechanical properties of the prepared packaging bag laminate decreased slightly, but the degradation performance remained unchanged.

[0121] In Example 8, the PE composite layer is composed of a single-layer PE film. As can be seen from Table 1, the tensile strength of the prepared packaging bag laminate is 48.6 MPa, and the tear strength is 87.9 KN / m. The five-layer PE film in Example 1 is composed of layer A, layer B, layer C, layer D, and layer E according to a certain thickness percentage. Comparing Example 6 with Example 1, it can be seen that the five-layer PE film composed of layer A, layer B, layer C, layer D, and layer E has better tensile strength and tear strength; while the degradation performance in Example 6 is the same as that in Example 1. In Example 9, an equal amount of acetate-modified starch is used to replace the modified acetate-modified starch. As can be seen from Table 1, the mechanical properties of the packaging bag laminate decrease significantly, and the degradation performance also decreases, indicating that the modified acetate-modified starch prepared in this application has excellent degradation performance, improves the film-forming property and degradation performance of the polyurethane inner layer, and greatly reduces environmental pollution.

[0122] In Examples 10-11, an equal amount of modified acetate-modified starch is used to replace polytetrahydrofuran ether diol or polyether triol. As can be seen from Table 1, the mechanical properties of the packaging bag laminate decrease significantly, and the degradation performance also decreases, indicating that some -OH in polytetrahydrofuran ether diol and polyether triol grafts with -NCO in isophorone diisocyanate. At the same time, the remaining hydroxyl groups in modified acetate-modified starch, polytetrahydrofuran ether diol, and polyether triol initiate the ring-opening polymerization reaction of caprolactone to form a ternary graft copolymer, and then form a crosslinked framework structure, ensuring the compatibility, film-forming property, and dispersibility of the product.

[0123] In Example 12, an equal amount of modified acetate-modified starch is used to replace aloe vera gel. As can be seen from Table 1, the mechanical properties of the packaging bag laminate decrease significantly, and the degradation performance also decreases, indicating that the aloe vera gel prepared in this application provides the environmental humidity required for degradation for microorganisms during microbial degradation, accelerating the degradation rate of the polyurethane inner layer. Aloe vera gel, as a plasticizer, stabilizer, and binder for degradable materials, enables the modified acetate-modified starch to form a film better, and makes the prepared polyurethane inner layer have better tensile strength, tensile strength, degradability, and environmental protection performance.

[0124] In Example 13, an equal amount of modified acetate-modified starch is used to replace wood cellulose. As can be seen from Table 1, the mechanical properties of the packaging bag laminate decrease significantly, and the degradation performance also decreases, indicating that the wood cellulose prepared in this application reduces the glass transition temperature Tg of the polyurethane inner layer and increases the degree of microphase separation during the subsequent degradation process of the polyurethane inner layer, promoting the degradation of the polyurethane inner layer. Moreover, wood cellulose is an organic flocculent fiber substance with excellent stability performance. The combination of wood cellulose and acetic anhydride solution further improves the adhesiveness of oxidized hydroxypropyl starch, and then improves the mechanical properties of the polyurethane inner layer.

[0125] In Example 14, the polyurethane inner layer is commercially available. As can be seen from Table 1, the mechanical properties of the packaging bag laminate significantly decrease, and the degradation performance also decreases, indicating that the polyurethane inner layer and the castor oil-based polyurethane layer prepared in this application have good mechanical properties and degradation rates.

[0126] In Comparative Example 1, both the polyurethane outer layer and the polyurethane inner layer are prepared from non-degradable raw materials. As can be seen from Table 1, the mechanical properties of the packaging bag laminate change significantly and decrease. However, since both the polyurethane outer layer and the polyurethane inner layer are non-degradable, the vacuum aluminum film cannot be recycled.

[0127] In Comparative Example 2, there are no through holes in the PE composite layer. As can be seen from Table 1, the mechanical properties of the packaging bag laminate are slightly better than those in Example 1, but the degradation performance significantly decreases. Because there are no through holes in the PE composite layer, microorganisms cannot pass through the PE composite layer to reach the polyurethane inner layer, so the polyurethane inner layer cannot be degraded. Only the polyurethane outer layer can be degraded. At the same time, the vacuum aluminum film cannot be recycled.

[0128] This specific embodiment is only an explanation of this application and is not a limitation thereof. Those skilled in the art can make modifications without creative contributions to this embodiment according to their needs after reading this specification, but as long as they are within the scope of the claims of this application, they are protected by the patent law.

Claims

1. A packaging bag laminate, characterized in that: It sequentially includes a polyurethane outer layer, a polyurethane aluminized composite layer, and a PE composite layer from outside to inside. The polyurethane aluminized composite layer includes a polyurethane inner layer and a vacuum aluminized film, wherein the vacuum aluminized film is connected to the polyurethane outer layer, and both the polyurethane outer layer and the polyurethane inner layer can be degraded; Wherein a plurality of through holes penetrating to the polyurethane inner layer are formed in the PE composite layer; The polyurethane inner layer is made of the following raw materials: modified acetate modified starch, polytetrahydrofuran ether diol, polyether triol, isophorone diisocyanate, aloe gel, 1,4-butanediol, methyl ethyl ketone, triethylamine, deionized water, silicone, and dibutyltin dilaurate; The preparation method of the modified acetate modified starch includes the following steps: S1. Prepare a saturated starch aqueous solution by dissolving oxidized hydroxypropyl starch at a temperature of 20-30°C; S2. Adjust the pH value of the saturated starch aqueous solution prepared in S1 to 9.5-10 using sodium bicarbonate; S3. Gradually drop the acetic anhydride solution into the solution prepared in S2. The mass ratio of acetic anhydride to starch is 12:15-10, the reaction temperature is 70-90°C, the reaction time is 2-3.5 h, then add lignocellulose and continue the reaction for 1-2 h, and finally cool down, filter, and wash to obtain the modified acetate modified starch; The raw material of the polyurethane outer layer is castor oil-based polyurethane, and the castor oil-based polyurethane is made of castor oil, polytetrahydrofuran ether diol, isophorone diisocyanate, dibutyltin dilaurate, triethylamine, deionized water, and 1,2,3-butanetriol.

2. The laminate for packaging bag according to claim 1, wherein: The thickness of the polyurethane outer layer is 10-15 μm, the thickness of the polyurethane aluminized composite layer is 13-17 μm, and the thickness of the PE composite layer is 180-200 μm.

3. The laminate for a packaging bag according to claim 1, characterized in that: The PE composite layer includes five PE film layers, namely layer A, layer B, layer C, layer D, and layer E. The thickness percentages of layer A, layer B, layer C, layer D, and layer E are (13%-17%):(13%-17%):(38%-42%):(13%-17%):(13%-17%).

4. A packaging bag laminate according to claim 1, wherein: The thickness of the vacuum aluminized film is 380-600 angstroms.

5. A packaging bag laminate according to claim 1, characterized in that: The diameter of the through hole is 0.5-2 mm.

6. The laminate for a packaging bag according to claim 1, wherein: There are 1-10 through holes per square centimeter in the PE composite layer.

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