Bonding resin, bonding resin composition, composite film and preparation method

Abstract

The invention relates to a bonding resin, a bonding resin composition, a composite film and a preparation method, the bonding resin comprises a graft polymer, and the graft polymer is prepared by grafting a polar monomer on a first polyolefin; the first polyolefin is selected from at least one of LLDPE, LDPE, HDPE, EVA and POE; the polar monomer is anhydride with alkenyl and a carboxylic acid compound with alkenyl; the mass ratio of the first polyolefin to the polar monomer is 100: (1-20). The adhesive resin is used for a lamination material, and can improve the stripping stability, chemical resistance and temperature resistance of a composite film.

Description

Technical Field

[0001] The present invention relates to the field of functional plastic bonding and laminating materials, and particularly to an adhesive resin, an adhesive resin composition, a composite film and a preparation method thereof. Background Art

[0002] Currently, in multi-layer composite packaging materials such as PET, BOPP composite aluminum foil, aluminized film, etc., the coating and gluing process is mostly used to produce composite films. The advantages of the coating and gluing process are small equipment investment and mature technology. The disadvantages are multiple processes, low efficiency, and VOC emission collection and treatment, resulting in high environmental protection costs.

[0003] To increase the production scale of composite films, some manufacturers use the extrusion coating and laminating process to produce multi-layer composite films. The extrusion coating and laminating process has fewer processes, high efficiency, reduces the problem of VOC emission collection and treatment, and saves costs. The disadvantages are large initial investment in laminating equipment and limited selection of bonding materials. Currently, there is a technical gap in the extrusion coating and laminating adhesive resin with good heat resistance, stable peel strength, and good chemical resistance. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the first object of the present invention is to provide an adhesive resin, which can improve the peel stability, chemical resistance and heat resistance of the composite film when used as a laminating material.

[0005] The second object of the present invention is to provide a preparation method of the above adhesive resin, which has the advantages of simple steps and the like.

[0006] The third object of the present invention is to provide a composition containing the above adhesive resin, which can be used as a laminating material to improve the peel stability, chemical resistance and heat resistance of the composite film.

[0007] The fourth object of the present invention is to provide a composite film containing the above adhesive resin composition, which has good peel stability, chemical resistance and heat resistance.

[0008] The fifth object of the present invention is to provide a preparation method of the above composite film, which can cooperate with the resin composition to obtain a composite film with good peel stability, chemical resistance and heat resistance, and is suitable for large-scale industrial production.

[0009] To achieve the first object of the present invention, the present invention provides an adhesive resin, which comprises a graft polymer prepared by grafting a polar monomer onto a first polyolefin; the first polyolefin is selected from at least one of LLDPE, LDPE, HDPE, EVA, and POE; the polar monomer is an acid anhydride with an alkenyl group and a carboxylic acid compound with an alkenyl group; the mass ratio of the first polyolefin to the polar monomer is 100:(1-20).

[0010] In some embodiments of the present invention, the acid anhydride with an alkenyl group is maleic anhydride or its derivative.

[0011] In some embodiments of the present invention, the carboxylic acid compound with an alkenyl group is at least one of acrylic acid and methacrylic acid.

[0012] In some embodiments of the present invention, the mass ratio of the acid anhydride with an alkenyl group to the carboxylic acid compound with an alkenyl group is 1:(0.2 - 5).

[0013] In some embodiments of the present invention, the adhesive resin further comprises an auxiliary agent, and the auxiliary agent is selected from at least one of an antioxidant, a stabilizer, an antistatic agent, an antibacterial agent, a mildew-proof agent, and a colorant; the mass ratio of the graft polymer to the auxiliary agent is 1:(0.01 - 0.05).

[0014] In some embodiments of the present invention, the mass ratio of the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, and the auxiliary agent is (50 - 90):(1 - 5):(1 - 5):(1 - 2).

[0015] To achieve the second object of the present invention, the present invention provides a method for preparing the adhesive resin according to any one of the above solutions, which comprises the following steps:

[0016] Step 1: Add the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, and the auxiliary agent into a high-speed mixer, mix evenly, and seal and stand still.

[0017] Step 2: Add the mixture obtained in Step 1 and the initiator into a twin-screw extruder respectively for extrusion reaction.

[0018] Step 3: Wash and dry the extruded product.

[0019] In some embodiments of the present invention, the mass ratio of the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, the initiator, and the auxiliary agent is (50 - 90):(1 - 5):(1 - 5):(1 - 4):(1 - 2).

[0020] In some embodiments of the present invention, the initiator is at least one of azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide.

[0021] In some embodiments of the present invention, in Step 1, the mixing temperature is 35 - 45°C, and the mixing time is 3 - 10 min.

[0022] In some embodiments of the present invention, in Step 2, the mixture obtained in Step 1 is added from the main feeding port of the extruder, and the initiator is added by a side feeding automatic metering system; the temperature of the extrusion reaction is 100 - 300°C.

[0023] In some embodiments of the present invention, in the third step, washing and drying the extruded product includes pelletizing the discharged extruded product, washing, filtering until neutral, and devolatilizing and drying to obtain the product.

[0024] To achieve the third object of the present invention, the present invention provides an adhesive resin composition, which comprises a uniformly mixed base material and an adhesive resin. The adhesive resin is the adhesive resin described in any of the above solutions, and the adhesive resin accounts for 10-30% of the total mass of the base material and the adhesive resin; the base material is a second polyolefin.

[0025] To achieve the fourth object of the present invention, the present invention provides a composite film, which comprises a base film and a resin layer covering at least one side of the base film. The resin layer is formed from the above-mentioned adhesive resin composition.

[0026] To achieve the fifth object of the present invention, the present invention provides a method for preparing the above composite film, which comprises the following steps:

[0027] Extrude the base film, and coat the liquefied adhesive resin composition onto the base film by a curtain coating process.

[0028] In some embodiments of the present invention, the base film is a metal, plastic or composite film of both.

[0029] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0030] The present invention provides a self-developed adhesive resin, adhesive resin composition, composite film and preparation method. The obtained composite film material can replace existing imported materials such as extruded PET, BOPP, aluminum foil, aluminized film, etc. The interlayer peel strength of the composite film is stable, without attenuation, resistant to acids, alkalis and various organic solvents, and has a relatively high use temperature. Detailed Embodiments

[0031] Embodiments of the present invention provide an adhesive resin, which is suitable for forming an adhesive resin composition with a base resin. The adhesive resin composition can prepare a composite film by an extrusion coating and curtain coating process. The obtained composite film has advantages such as good peel strength stability, good heat resistance, and good chemical resistance, and can be used as a packaging film, such as a packaging film for food including sauces. Of course, the composite film of this embodiment can also be used in other packaging scenarios.

[0032] The adhesive resin of this embodiment includes a graft polymer, which is prepared by grafting a polar monomer onto a first polyolefin. The polar monomer can improve the adhesion performance of the material. Among them, the first polyolefin is selected from at least one of LLDPE, LDPE, HDPE, EVA, and POE. The first polyolefin itself has a low polarity and can graft a side-chain polymer through an initiator. The polar monomer is an acid anhydride with an alkenyl group and a carboxylic acid compound with an alkenyl group. The alkenyl groups in their molecules can participate in polymerization to form a graft chain covalently connected to the first polyolefin on the molecular chain of the first polyolefin. At the same time, the acid anhydride group and the carboxylic acid group have polarity and certain reactivity. The obtained graft polymer can improve the adhesion of the material through chemical reactions or intermolecular forces. The acid anhydride with an alkenyl group and the carboxylic acid compound with an alkenyl group are used in combination, which can increase the polarity and reactivity of the material when introduced into the polyolefin, improve the compatibility and adhesion of the material with other polar substances, such as enhancing the adhesion performance of the polyolefin with materials such as metal and glass. Among them, the acid anhydride can also endow the resin with better heat resistance, weather resistance, and mechanical properties, broadening the application field of the material.

[0033] Among them, the mass ratio of the first polyolefin to the polar monomer is 100:(1 - 20), for example, it can be 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, 100:15, 100:16, 100:17, 100:18, 100:19, 100:20, etc. When the mass ratio of the first polyolefin to the polar monomer is within the above range, the obtained graft polymer has good adhesion and good storage stability, and will not become sticky during storage. The adhesive resin of this embodiment meets the safety requirements and is consistent with the transportation and storage methods of conventional polyolefin resin materials, and does not require special storage.

[0034] In some examples, the acid anhydride with an alkenyl group is maleic anhydride or its derivative, and the derivative of maleic anhydride can be a substituent of maleic anhydride, etc. Maleic anhydride or its derivative has both an alkenyl group and an acid anhydride group, can participate in the graft reaction, improve the polarity of the resin, thereby improving the adhesion performance of the material, and can also improve the mechanical properties and temperature resistance of the material, and has the advantages of easy availability of raw materials.

[0035] In some examples, the carboxylic acid compound with an alkenyl group is at least one of acrylic acid and methacrylic acid. Acrylic acid and methacrylic acid can participate in the graft reaction, improve the polarity of the resin, and have the advantages of easy availability of raw materials.

[0036] In some examples, the mass ratio of the acid anhydride with an alkenyl group to the carboxylic acid compound with an alkenyl group is 1:(0.2 - 5). For example, the mass ratio of the acid anhydride with an alkenyl group to the carboxylic acid compound with an alkenyl group can be 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1, 1:2, 1:3, 1:4, 1:5, etc. When the mass ratio of the two is within the above range, the adhesiveness of the obtained adhesive resin is better.

[0037] In some examples, the adhesive resin further includes an auxiliary agent. The auxiliary agent can be a processing auxiliary agent or a functional auxiliary agent, and can be selected from at least one of antioxidants, stabilizers, antistatic agents, antibacterial agents, mildew-proof agents, and colorants. The mass ratio of the graft polymer to the auxiliary agent can be 1:(0.01 - 0.05), such as 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, etc., to provide corresponding improved functions.

[0038] In some examples, the mass ratio of the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, and the auxiliary agent is (50 - 90):(1 - 5):(1 - 5):(1 - 2), for example, it can be (80 - 90):(3 - 5):(2 - 5):(1 - 2). When the dosage of each raw material is within the above range, the performance of the obtained material is better.

[0039] In some examples, the preparation method of the above adhesive resin includes the following steps:

[0040] Step 1: Add the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, and the auxiliary agent into a high-speed mixer, mix evenly and seal for static placement to make the above raw materials mix evenly.

[0041] Step 2: Add the mixture obtained in Step 1 and the initiator into a twin-screw extruder respectively for extrusion reaction to graft the acid anhydride with an alkenyl group and the carboxylic acid compound with an alkenyl group onto the first polyolefin to form polar side chains.

[0042] Step 3: Wash and dry the extrusion product.

[0043] It can be seen that the above preparation method has simple steps, the obtained adhesive resin has low impurity content and good adhesion performance.

[0044] In some examples, the mass ratio of the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, the initiator, and the auxiliary agent is (50 - 90):(1 - 5):(1 - 5):(1 - 4):(1 - 2), for example, (80 - 90):(3 - 5):(2 - 5):(2 - 4):(1 - 2). When the dosage ratio of the initiator to other raw materials is within the above range, the grafted chain distribution is uniform, the grafted chain length is appropriate, while providing greater adhesion force, the existence of small crystal points is reduced, which is beneficial to the subsequent mixing of the adhesive resin with the base material and the dispersion of the raw materials.

[0045] In some examples, the first polyolefin can be selected from products of manufacturers such as Sinopec, Shell, Dow, and Basell. The anhydride can be selected from products of manufacturers such as Shandong Huilong and Shengze. The initiator can be selected from products of manufacturers such as Nouryon and Mackerey. The auxiliary agent can be selected from products of manufacturers such as BASF and Rianlon.

[0046] In some examples, the initiator is at least one of azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide, and the above initiator can initiate the grafting reaction under heating conditions.

[0047] In some examples, in Step 1, the mixing temperature is 35 - 45 °C and the mixing time is 3 - 10 min to make the raw materials mix more evenly.

[0048] In some examples, in Step 2, the mixture obtained in Step 1 is added from the main feed port of the extruder, and the initiator is added by a side feed automatic metering system. For example, the initiator can be added in segments along the length of the screw of the extruder, which is beneficial to the control of the grafting reaction. The temperature of the extrusion reaction is 100 - 300 °C, which is beneficial to rapid grafting and has a wide processing temperature adaptation range.

[0049] In some examples, in Step 3, washing and drying the extrusion product includes pelletizing the discharged extrusion product, washing, filtering until neutral, and devolatilizing and drying to obtain the product, which improves the purity of the adhesive resin.

[0050] In some examples, this embodiment also provides an adhesive resin composition, which includes a uniformly mixed base material and the above adhesive resin. The base material and the adhesive resin can be uniformly mixed in the form of particles or powders, or can be melt - blended, such as extrusion - blended uniformly. The adhesive resin accounts for 10 - 30% of the total mass of the base material and the adhesive resin. For example, 10%, 15%, 20%, 25%, 30%, etc., and the appropriate addition amount can be selected according to the adhesive force requirement to obtain different peel strengths and meet the bonding requirements of various products, which is flexible to use and cost - saving. Among them, the base material is a second polyolefin, which can be selected from at least one of LLDPE, LDPE, HDPE, EVA, and POE. The second polyolefin and the first polyolefin can be of the same or different types. The same type is beneficial to the compatibility between the base material and the adhesive resin. The adhesive resin can be directly mixed with the base material without drying.

[0051] In some examples, this embodiment also provides a composite film, which includes a base film and a resin layer covering at least one side of the base film. The resin layer is formed from the above adhesive resin composition. The multi - layer composite film has better barrier properties and can be applicable to the packaging of special items such as food.

[0052] In some examples, the method for preparing the composite film comprises the following steps:

[0053] Extrude the base film, and coat the liquefied adhesive resin composition onto the base film by the film laminating process.

[0054] This preparation method adopts the extrusion coating and laminating process, making the adhesive resin composition firmly bonded to the base film, and the obtained composite film does not require curing, reducing VOC emissions. Moreover, this preparation method is simple and convenient, reducing the process flow and having high production efficiency.

[0055] In some examples, the liquefied adhesive resin composition can be the melt of the adhesive resin composition.

[0056] In some examples, the base film is a metal, plastic or composite film of both. For example, it can be PET, BOPP composite aluminum foil, aluminized film, etc.

[0057] The technical solution of the present invention will be further described in detail through specific examples below. In the following examples and comparative examples, the substances with the same name are from the same source. Among them, low-density polyethylene is purchased from Sinopec, maleic anhydride is purchased from Shandong Longhui, methacrylic acid is purchased from Shandong Xinjieao, initiators azobisisobutyronitrile, azodiisooctanenitrile and benzoyl peroxide are purchased from Nouryon, and the antioxidant is purchased from BASF.

[0058] Example 1

[0059] According to the weight ratio of each raw material component, 90 parts of low-density polyethylene, 3 parts of maleic anhydride, 2 parts of methacrylic acid, and 1 part of antioxidant are added to a high-speed mixer, mixed evenly at 40°C for 5 minutes, and then sealed and left standing.

[0060] Add the raw material mixture pretreated in the above step to the main feeding port of a twin-screw extruder, and add 4 parts of initiator (an equal-mass mixture of azobisisobutyronitrile, azodiisooctanenitrile and benzoyl peroxide) to the reaction extrusion equipment through the side feeding automatic metering system, and carry out extrusion grafting reaction at about 150°C.

[0061] Granulate the reaction product through the discharge port, wash, filter to neutral, and remove volatiles and dry to obtain the adhesive resin product.

[0062] Example 2

[0063] According to the weight ratio of each raw material component, 80 parts of low-density polyethylene, 5 parts of maleic anhydride, 5 parts of methacrylic acid, and 2 parts of antioxidant are added to a high-speed mixer, mixed evenly at 40°C for 5 minutes, and then sealed and left standing.

[0064] Add the pre-treated raw material mixture in the above steps to the main feeding port of a twin-screw extruder, and add 2 parts of initiator (an equimolar mixture of azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile) and benzoyl peroxide) to the reactive extrusion equipment through a side-feeding automatic metering system, and carry out an extrusion grafting reaction at about 150 °C.

[0065] Pelletize the reaction product through the discharge port, wash, filter it to neutrality, and remove volatiles and dry it to obtain a bonding resin product.

[0066] Example 3

[0067] According to the weight ratio of each raw material component, add 85 parts of low-density polyethylene, 5 parts of maleic anhydride, 1 part of methacrylic acid, and 2 parts of antioxidant to a high-speed mixer, mix evenly at 40 °C for 5 minutes, and then seal and let stand.

[0068] Add the pre-treated raw material mixture in the above steps to the main feeding port of a twin-screw extruder, and add 2 parts of initiator (an equimolar mixture of azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile) and benzoyl peroxide) to the reactive extrusion equipment through a side-feeding automatic metering system, and carry out an extrusion grafting reaction at about 150 °C.

[0069] Pelletize the reaction product through the discharge port, wash, filter it to neutrality, and remove volatiles and dry it to obtain a bonding resin product.

[0070] Example 4

[0071] According to the weight ratio of each raw material component, add 85 parts of low-density polyethylene, 1 part of maleic anhydride, 5 parts of methacrylic acid, and 2 parts of antioxidant to a high-speed mixer, mix evenly at 40 °C for 5 minutes, and then seal and let stand.

[0072] Add the pre-treated raw material mixture in the above steps to the main feeding port of a twin-screw extruder, and add 1 part of initiator (an equimolar mixture of azobisisobutyronitrile, azobis(2,4-dimethylvaleronitrile) and benzoyl peroxide) to the reactive extrusion equipment through a side-feeding automatic metering system, and carry out an extrusion grafting reaction at about 150 °C.

[0073] Pelletize the reaction product through the discharge port, wash, filter it to neutrality, and remove volatiles and dry it to obtain a bonding resin product.

[0074] Comparative Example 1

[0075] According to the weight ratio of each raw material component, add 85 parts of low-density polyethylene, 8 parts of methacrylic acid, and 1 part of antioxidant to a high-speed mixer, mix evenly at 40 °C for 5 minutes, and then seal and let stand.

[0076] Add the pre-treated raw material mixture in the above steps to the main feeding port of a twin-screw extruder, and add 4 parts of initiator (an equimolar mixture of azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide) to the reactive extrusion equipment through a side feeding automatic metering system, and conduct an extrusion grafting reaction at about 150 °C.

[0077] Pelletize the reaction product through the discharge port, wash, filter it to neutrality, and remove volatiles and dry to obtain the adhesive resin product.

[0078] Comparative Example 2

[0079] According to the weight ratio of each raw material component, add 85 parts of low-density polyethylene, 8 parts of maleic anhydride, and 1 part of antioxidant to a high-speed mixer, mix evenly at 40 °C for 5 minutes, and then seal and let stand.

[0080] Add the pre-treated raw material mixture in the above steps to the main feeding port of a twin-screw extruder, and add 4 parts of initiator (an equimolar mixture of azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide) to the reactive extrusion equipment through a side feeding automatic metering system, and conduct an extrusion grafting reaction at about 150 °C.

[0081] Pelletize the reaction product through the discharge port, wash, filter it to neutrality, and remove volatiles and dry to obtain the adhesive resin product.

[0082] Comparative Example 3

[0083] According to the weight ratio of each raw material component, add 80 parts of low-density polyethylene, 10 parts of maleic anhydride, 10 parts of methacrylic acid, and 1 part of antioxidant to a high-speed mixer, mix evenly at 40 °C for 5 minutes, and then seal and let stand.

[0084] Add the pre-treated raw material mixture in the above steps to the main feeding port of a twin-screw extruder, and add 4 parts of initiator (an equimolar mixture of azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide) to the reactive extrusion equipment through a side feeding automatic metering system, and conduct an extrusion grafting reaction at about 150 °C.

[0085] Pelletize the reaction product through the discharge port, wash, filter it to neutrality, and remove volatiles and dry to obtain the adhesive resin product.

[0086] Prepare a composite film:

[0087] Respectively mix the adhesive resins obtained in the above examples and comparative examples with the base material low-density polyethylene in different proportions (10%, 20% of the total mass) in a high-speed mixer at 25 °C for 10 minutes to obtain an adhesive resin composition.

[0088] Melt the adhesive resin composition at 130 °C and coat it on both sides of the extruded substrate through a film laminating process to obtain a composite film. The thickness of a single resin layer is 0.05 mm.

[0089] The adhesion and peel strength of the obtained composite film was tested according to the test method of GB / T 2790, and the results are shown in Table 1 below.

[0090] Table 1 Adhesion and Peel Strength Test

[0091]

[0092]

[0093] As can be seen from the above, for the composite film prepared in the embodiment of the present invention, the adhesion and peel strength to the aluminum foil substrate is greater than 3.0 N / 15 mm, and the adhesion and peel strength to PET and aluminized PET is greater than 2.0 N / 15 mm, which can well meet the application requirements of food packaging film bags.

[0094] The obtained extrusion-coated composite film with a binder resin content of 10% and an aluminum foil substrate was made into packaging film bags of the same size according to the same process. The following treatments were carried out on the packaging film bags respectively, and the color change and leakage of the film material were observed, and the interlayer peel strength of the film was tested with reference to GB / T 2790. The results are shown in Table 2 below.

[0095] Table 2 Test Results of Packaging Film Bags

[0096]

[0097]

[0098] As can be seen from the above, the packaging film prepared in the embodiment of the present invention has better chemical resistance and heat resistance, can maintain a stable peel force for a long time, and is suitable for encapsulating high-acidity slurries.

[0099] Finally, it should be emphasized that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A bonding resin, characterized in that It includes a graft polymer which is prepared by grafting a polar monomer onto a first polyolefin; The first polyolefin is selected from at least one of LLDPE, LDPE, HDPE, EVA, and POE; The polar monomer is an acid anhydride with an alkenyl group and a carboxylic acid compound with an alkenyl group; The mass ratio of the first polyolefin to the polar monomer is 100:(1 - 20).

2. The adhesive resin according to claim 1, wherein The acid anhydride with an alkenyl group is maleic anhydride or its derivative; The carboxylic acid compound with an alkenyl group is at least one of acrylic acid and methacrylic acid.

3. The adhesive resin according to claim 1 or 2, characterized in that The mass ratio of the acid anhydride with an alkenyl group to the carboxylic acid compound with an alkenyl group is 1:(0.2 - 5).

4. The adhesive resin according to claim 1 or 2, characterized in that It further includes an auxiliary agent which is selected from at least one of an antioxidant, a stabilizer, an antistatic agent, an antibacterial agent, a mildew-proof agent, and a colorant; the mass ratio of the graft polymer to the auxiliary agent is 1:(0.01 - 0.05).

5. The adhesive resin according to claim 4, wherein The mass ratio of the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, and the auxiliary agent is (50 - 90):(1 - 5):(1 - 5):(1 - 2).

6. The method for preparing the adhesive resin according to any one of claims 1 to 5, characterized in that It includes the following steps: Step 1: Add the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, and the auxiliary agent into a high-speed mixer, mix evenly, and seal and stand still; Step 2: Add the mixture obtained in Step 1 and the initiator into a twin-screw extruder respectively for extrusion reaction; Step 3: Wash and dry the extruded product.

7. According to the preparation method described in claim 6, it is characterized in that: The mass ratio of the first polyolefin, the acid anhydride with an alkenyl group, the carboxylic acid compound with an alkenyl group, the initiator, and the auxiliary agent is (50 - 90):(1 - 5):(1 - 5):(1 - 4):(1 - 2); The initiator is at least one of azobisisobutyronitrile, azobisisoheptonitrile, and benzoyl peroxide; In Step 1, the mixing temperature is 35 - 45°C and the mixing time is 3 - 10 min; In Step 2, the mixture obtained in Step 1 is added from the main feeding port of the extruder, and the initiator is added by a side feeding automatic metering system; the temperature of the extrusion reaction is 100 - 300°C; In Step 3, washing and drying the extruded product includes pelletizing the discharged extruded product, washing, filtering until neutral, and devolatilizing and drying to obtain the product.

8. An adhesive resin composition, characterized in that It includes a uniformly mixed base material and an adhesive resin, the adhesive resin is the adhesive resin described in any one of claims 1 to 5 or the adhesive resin obtained by the preparation method described in claim 6 or 7, and the adhesive resin accounts for 10 - 30% of the total mass of the base material and the adhesive resin; the base material is a second polyolefin.

9. A composite film, characterized in that It includes a base film and a resin layer covering at least one side of the base film, and the resin layer is formed by the adhesive resin composition described in claim 8.

10. The method for preparing the composite film according to claim 9, characterized in that It includes the following steps: Extrude the base film, and coat the liquefied adhesive resin composition onto the base film by a curtain coating process; The base film is a metal, a plastic, or a composite film of both.

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