Multi-layer composite hot melt adhesive film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer material preparation, in particular to a multi-layer composite hot melt adhesive film and a preparation method and application thereof.The multi-layer composite hot melt adhesive film at least comprises a layer A, a layer B and a layer C. The layer A and the layer C are composited through the layer B. The layer A is a polyolefin hot melt adhesive film, the layer B is a modified polyamide film, and the layer C is a polyurethane hot melt adhesive film; the modified polyamide membrane at least comprises the following preparation raw materials in parts by weight: 80-120 parts of long carbon chain nylon, 5-50 parts of polystyrene, 0.1-8 parts of maleic anhydride monomer, 0.1-1 part of peroxide and 0.5-2 parts of solvent, a polar material and a non-polar material can be bonded together through hot pressing, and the modified polyamide membrane is prepared through hot pressing. The bonding and compounding requirements between metal and polar materials such as at least one polar material of polycarbonate, acrylonitrile-butadiene-styrene plastic, polyurethane or glass fiber reinforced materials in automotive trim or other application scenes are met.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material preparation, and specifically relates to a multi-layer composite hot melt adhesive film, a preparation method thereof, and an application thereof. Background Art

[0002] There are many injection-molded parts in automobile spare parts. For the parts that can be seen by people in the car, a certain texture (such as matte, shiny, carbon fiber, pattern, etc.) is required. It is difficult to achieve the effect on the surface of the injection-molded parts and it is not durable. The general process is to first stamp an aluminum alloy sheet into the same shape as the injection-molded part, and then perform printing, water transfer printing or film laminating on the surface of the aluminum alloy to achieve effects such as matte, shiny, carbon fiber, pattern, etc. Then, the aluminum alloy and the injection-molded part are glued together, or the aluminum alloy sheet is first stamped and formed and glued to the injection-molded part, and then the surface of the aluminum alloy is treated. This process has complex procedures, and there are tolerances between the stamping of the aluminum alloy sheet and the injection-molded part, resulting in a low yield rate. At the same time, gluing affects the VOC test results.

[0003] Based on the above problems, the vehicle factory hopes to optimize the process by stamping and forming the aluminum alloy sheet, then directly injection-molding in the cavity of the formed aluminum alloy sheet, and finally treating the surface of the aluminum alloy. On the one hand, the gluing process can be omitted and the VOC meets the standard; on the other hand, direct injection-molding in the aluminum alloy cavity eliminates the tolerance problem between the aluminum alloy and the injection-molded part, and the yield rate is greatly improved. However, the problem faced by the optimized process is that bonding metals requires non-polar materials, usually polyolefin-based (such as polyethylene, ethylene-vinyl acetate copolymer, ethylene propylene diene monomer rubber, ethylene acrylic copolymer, etc.) hot melt adhesive films, and injection-molding materials are usually polar materials, including at least one polar material among polycarbonate, acrylonitrile-butadiene-styrene plastic, polyurethane, or glass fiber-reinforced material. Non-polar materials and polar materials are incompatible, and it is difficult to make a film that can bond both metals and the above-mentioned polar materials. Chinese Patent (authorized publication number CN101429413B) discloses a double-layer composite hot melt adhesive film for bonding metal and plastic, which meets the bonding requirements of metal and plastic by directly compounding different hot melt adhesives for bonding metal and plastic after modification. However, the adhesion between the upper and lower double-layer films of this hot melt adhesive is poor, resulting in a low peel strength for metal and plastic. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a multi-layer composite hot melt adhesive film, which can bond polar materials and non-polar materials together by hot pressing, and meet the bonding and compounding requirements between metals and at least one polar material such as polycarbonate, acrylonitrile-butadiene-styrene plastic, polyurethane, or glass fiber-reinforced material in automotive interiors or other application scenarios.

[0005] On the one hand, the present invention provides a multi-layer composite hot melt adhesive film, which at least includes layer A, layer B and layer C. Layer A and layer C are compounded through layer B, wherein: layer A is a polyolefin hot melt adhesive film, layer B is a modified polyamide film, and layer C is a polyurethane hot melt adhesive film.

[0006] In one embodiment, the thickness ranges of layer A, layer B and layer C are all 0.003 - 0.1 mm.

[0007] In one embodiment, the thickness range of the polyolefin hot melt adhesive film is 0.003 - 0.05 mm.

[0008] In one embodiment, the thickness range of the polyolefin hot melt adhesive film is 0.02 - 0.025 mm.

[0009] In one embodiment, the thickness range of the modified polyamide film is 0.003 - 0.05 mm.

[0010] In one embodiment, the thickness range of the modified polyamide film is 0.015 - 0.025 mm.

[0011] In one embodiment, the thickness range of the polyurethane hot melt adhesive film is 0.003 - 0.05 mm.

[0012] In one embodiment, the thickness range of the polyurethane hot melt adhesive film is 0.010 - 0.015 mm.

[0013] In one embodiment, the raw materials for preparing the modified polyamide film, by weight, at least include: 80 - 120 parts of long-chain nylon, 5 - 50 parts of polystyrene, 0.1 - 8 parts of maleic anhydride monomer, 0.1 - 1 part of peroxide, and 0.5 - 2 parts of solvent.

[0014] In one embodiment, the raw materials for preparing the modified polyamide film, by weight, at least include: 100 parts of long-chain nylon, 10 - 30 parts of polystyrene, 3 - 5 parts of maleic anhydride monomer, 0.2 - 0.5 part of peroxide, and 0.5 - 1.5 parts of solvent.

[0015] In one embodiment, the number of carbon atoms of the long-chain nylon ≥ 10.

[0016] In one embodiment, the melting point of the long-chain nylon ≤ 220 °C.

[0017] In one embodiment, the long-chain nylon is selected from at least one of modified or unmodified PA12, PA1212, PA11 or PA612.

[0018] In one embodiment, the long-chain nylon is selected from one of PA12, PA1212, PA11 or PA612.

[0019] In one embodiment, the long-chain nylon is PA12 or PA612. The grade of PA12 is Wanhua Nylon PA12 L2000, and the grade of PA612 is Swiss EMS D1523A.

[0020] In one embodiment, the peroxide is dicumyl peroxide (DCP).

[0021] In one embodiment, the solvent is acetone.

[0022] The purpose of the multi-layer composite hot melt adhesive film provided by the present invention is to achieve the composite between polar materials and non-polar materials, especially the adhesive composite between metals and injection-molded materials. One layer of the multi-layer composite hot melt adhesive film is a polyolefin hot melt adhesive film, which can be hot-pressed and bonded with non-polar metal materials, and the other layer is a polyolefin hot melt adhesive film, which can be used with at least one polar material such as polar polycarbonate, acrylonitrile-butadiene-styrene plastic, polyurethane or glass fiber reinforced material, so as to achieve the bonding and composite between polar-non-polar materials. However, in the process of compounding the polyolefin hot melt adhesive film and the polyurethane hot melt adhesive film in the present invention, it is found that the interlayer peel strength between the polyolefin hot melt adhesive film and the polyurethane hot melt adhesive film is low, and the peel strength with polar materials and non-polar materials also needs to be further improved. In the early stage of the present invention, the selection of the polyolefin hot melt adhesive film was optimized, but the improvement of the interlayer peel strength and the peel strength between it and polar and non-polar materials is small.

[0023] In further exploration of the present invention, it is found that by setting a modified polyamide film between the polyolefin hot melt adhesive film and the polyurethane hot melt adhesive film, and designing the modified polyamide film to be prepared from long-chain nylon, and compounding and adding maleic anhydride monomer, polystyrene and peroxide for modification, the obtained modified polyamide film has good adhesiveness, flexibility and heat resistance, and can have good compatibility with the materials of layer A and layer C, and the co-extrusion processing is not delaminated. In particular, the modified polyamide film prepared from one of PA12, PA1212, PA11 or PA612 has extremely high adhesion fastness with both the polyolefin hot melt adhesive film and the polyurethane hot melt adhesive film. The interlayer peel strength, the peel strength with metal and the peel strength with TPU are all > 4 kg / 2.5 cm, and there will be no delamination or falling-off problems, better meeting the actual application requirements.

[0024] In one embodiment, the preparation raw materials of the polyolefin hot melt adhesive film include polyolefin resin.

[0025] In one embodiment, the polyolefin resin is selected from at least one of polyethylene, ethylene-vinyl acetate copolymer, ethylene propylene diene monomer rubber, or ethylene acrylic acid copolymer.

[0026] In one embodiment, the melt mass flow rate (2.16 kg, 190 °C) of the polyolefin resin is 1.5 - 75 g / 10 min.

[0027] In one embodiment, the polyolefin resin is ethylene acrylic acid copolymer, the melt mass flow rate (2.16 kg, 190 °C) is 7.8 g / 10 min, and the grade is PRIMACOR TM 3003, sourced from SK Functional Polymers.

[0028] In one embodiment, the polyolefin resin is polyethylene, and the polyethylene is maleic anhydride grafted modified polyethylene, the melt mass flow rate (2.16 kg, 190 °C) is 9.2 g / 10 min, and the grade is ADMERTM MF528, sourced from Mitsui Chemicals.

[0029] In one embodiment, the raw materials for preparing the polyurethane hot melt adhesive film at least include polyurethane resin.

[0030] In one embodiment, the raw materials for preparing the polyurethane hot melt adhesive film, by weight, at least include 90 - 100 parts of polyurethane resin and 2 - 8 parts of slip agent.

[0031] In one embodiment, the polyurethane resin is thermoplastic polyurethane elastomer.

[0032] In one embodiment, the thermoplastic polyurethane elastomer is polyester-based thermoplastic polyurethane elastomer.

[0033] In one embodiment, the melting point range of the polyester-based thermoplastic polyurethane elastomer is 60 - 180 °C.

[0034] In one embodiment, the melting point of the polyester-based thermoplastic polyurethane elastomer is 105 °C, and the grade is HF-3H85A, sourced from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd.

[0035] In one embodiment, the melting point of the polyester-based thermoplastic polyurethane elastomer is 120 °C, and the grade is Lubrizol's 58271.

[0036] In one embodiment, the slip agent is Lubrizol slip agent T5075.

[0037] In one embodiment, the mass ratio of the polyolefin resin to the long-chain nylon is 1:(0.8 - 1.2).

[0038] In one embodiment, the mass ratio of the polyolefin resin to the long-chain nylon is 1:1.

[0039] Furthermore, by optimizing the polyolefin-based hot melt adhesive film and the polyurethane-based hot melt adhesive film, in the presence of the modified polyamide film, the present invention greatly improves the bonding strength between aluminum metal and polycarbonate, acrylonitrile-butadiene-styrene plastic, polycarbonate and acrylonitrile-butadiene-styrene blend alloy plastic, thermoplastic polyurethane or the above materials and glass fiber reinforced materials.

[0040] On the other hand, the present invention provides a method for preparing a multi-layer composite hot melt adhesive film, which at least includes the following steps: separately preparing layer A, layer B, and layer C, and then hot-pressing and bonding layer A, layer B, and layer C, or preparing layer A raw material, layer B raw material, and layer C raw material through a three-layer co-extrusion device.

[0041] In one embodiment, the method for preparing the multi-layer composite hot melt adhesive film at least includes the following steps: preparing granular materials for layer B and performing dehumidifying and drying; stirring and mixing the raw materials for layer C and then performing dehumidifying and drying; putting the raw materials for layer A, the granular materials for layer B, and the raw materials for layer C into three screws of a three-layer co-extrusion blown film machine, and co-extruding into a film to obtain the multi-layer composite hot melt adhesive film.

[0042] In one embodiment, the method for preparing the granular materials for layer B is as follows: mixing maleic anhydride monomer, peroxide, and solvent into a solution, stirring and mixing the solution with long-chain nylon and polystyrene to obtain a mixture, adding the mixture to a twin-screw extruder, extruding, pelletizing, cutting, and drying to obtain the granular materials for layer B.

[0043] In one embodiment, the process parameters of the twin-screw extruder are set as follows: zone 1: 175 - 180 °C, zone 2: 185 - 190 °C, zone 3: 195 - 230 °C, zone 4: 195 - 230 °C.

[0044] In one embodiment, the parameter settings of the three screws of the three-layer co-extrusion blown film machine include: the temperature setting of the screw for layer A: zone 1: 160 °C, zone 2: 163 °C, zone 3: 168 °C, zone 4: 168 °C; the temperature setting of the screw for layer B: zone 1: 175 °C, zone 2: 180 °C, zone 3: 190 °C, zone 4: 190 °C; the temperature setting of the screw for layer C: zone 1: 168 °C, zone 2: 170 °C, zone 3: 172 °C, zone 4: 175 °C; the die head temperature is set to 175 - 185 °C.

[0045] In one embodiment, the temperature for dehumidifying and drying is 70 - 80 °C, and the time is ≥ 4 h.

[0046] The third aspect of the present invention provides an application of a multi-layer composite hot melt adhesive film for the composite between a metal and at least one polar material among polycarbonate, acrylonitrile-butadiene-styrene plastic, thermoplastic polyurethane or glass fiber reinforced material.

[0047] Beneficial effects

[0048] 1. The present invention provides a multi-layer composite hot melt adhesive film, which can bond polar materials and non-polar materials together through hot pressing, meeting the bonding and composite requirements between a metal and at least one polar material such as polycarbonate, acrylonitrile-butadiene-styrene plastic, polyurethane or glass fiber reinforced material in automotive interiors or other application scenarios.

[0049] 2. The present invention sets a modified polyamide film between a polyolefin-based hot melt adhesive film and a polyurethane-based hot melt adhesive film. The modified polyamide film is designed to be prepared from long-chain nylon, and is modified by adding maleic anhydride monomer, polystyrene and peroxide, so that the obtained modified polyamide film has good adhesiveness, flexibility and heat resistance, and can have good compatibility with the materials of layer A and layer C, and there is no delamination during co-extrusion processing.

[0050] 3. By optimizing the polyolefin-based hot melt adhesive film and the polyurethane-based hot melt adhesive film, the present invention greatly improves the composite between aluminum metal materials and polycarbonate, acrylonitrile-butadiene-styrene plastic, polycarbonate and acrylonitrile-butadiene-styrene blend alloy plastic, thermoplastic polyurethane or the above materials and glass fiber reinforced material in the presence of the modified polyamide film.

[0051] 4. The modified polyamide film prepared by using one of PA12, PA1212, PA11 or PA612 in the present invention has extremely high adhesion fastness with both the polyolefin-based hot melt adhesive film and the polyurethane-based hot melt adhesive film. The interlayer peel strength, the peel strength with metal, and the peel strength with TPU (thermoplastic polyurethane elastomer) are all > 4 kg / 2.5 cm, and there will be no delamination or peeling problems, better meeting the actual application requirements.

[0052] 5. The preparation method of the multi-layer composite hot melt adhesive film provided by the present invention is simple and easy to control, greatly reducing the difficulty and cost of industrial production, and having high practical value. Detailed implementation manners

[0053] Example 1

[0054] One aspect of Example 1 of the present invention provides a multi-layer composite hot melt adhesive film, including layer A, layer B and layer C. Layer A and layer C are composite through layer B, wherein: layer A is a polyolefin-based hot melt adhesive film, layer B is a modified polyamide film, and layer C is a polyurethane-based hot melt adhesive film.

[0055] The thickness of the polyolefin hot melt adhesive film is 0.02 mm, the thickness of the modified polyamide film is 0.015 mm, and the thickness of the polyurethane hot melt adhesive film is 0.010 mm.

[0056] The raw materials for preparing the modified polyamide film, by weight, include: 100 parts of long-chain nylon, 20 parts of polystyrene, 4 parts of maleic anhydride monomer, 0.3 parts of peroxide, and 1 part of solvent.

[0057] The long-chain nylon is PA12, and the grade of the PA12 is Wanhua Nylon PA12 L2000.

[0058] The peroxide is dicumyl peroxide (DCP).

[0059] The solvent is acetone.

[0060] The grade of the polystyrene is GP5350, sourced from Formosa Plastics; the grade of the maleic anhydride monomer is Xuchen 13, sourced from Shandong Xuchen Chemical Industry.

[0061] The raw materials for preparing the polyolefin hot melt adhesive film include polyolefin resin. The polyolefin resin is ethylene acrylic copolymer, with a melt mass flow rate (2.16 kg, 190 °C) of 7.8 g / 10 min, and the grade is PRIMACOR TM 3003, sourced from SK Functional Polymers.

[0062] The raw materials for preparing the polyurethane hot melt adhesive film, by weight, include 96 parts of polyurethane resin and 4 parts of slip agent.

[0063] The melting point of the polyester-based thermoplastic polyurethane elastomer is 105 °C, the grade is HF-3H85A, sourced from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd.

[0064] The slip agent is Lubrizol Slip Agent T5075.

[0065] The mass ratio of the polyolefin resin to the long-chain nylon is 1:1.

[0066] On the other hand, Example 1 of the present invention provides a method for preparing a multi-layer composite hot melt adhesive film, including the following steps: preparing the B-layer granular material and performing dehumidifying drying at 80 °C for 5 h; stirring and mixing the C-layer raw materials and performing dehumidifying drying at 70 °C for 5 h; putting the A-layer raw materials, B-layer granular materials, and C-layer raw materials into three screws of a three-layer co-extrusion blown film machine, and obtaining the multi-layer composite hot melt adhesive film after co-extrusion into a film.

[0067] The preparation method of the granular material of layer B is as follows: Mix maleic anhydride monomer, peroxide and solvent to form a solution, stir and mix the solution with long-chain nylon and polystyrene to obtain a mixture, add the mixture to a twin-screw extruder, extrude and pelletize, cut the pellets, and dry them to obtain the granular material of layer B.

[0068] The process parameters of the twin-screw extruder are set as follows: Zone 1: 175 °C, Zone 2: 185 °C, Zone 3: 195 °C, Zone 4: 195 °C.

[0069] The parameter settings of the three screws of the three-layer coextrusion blown film machine include: For the screw of layer A, the temperature is set as follows: Zone 1: 160 °C, Zone 2: 163 °C, Zone 3: 168 °C, Zone 4: 168 °C; for the screw of layer B, the temperature is set as follows: Zone 1: 175 °C, Zone 2: 180 °C, Zone 3: 190 °C, Zone 4: 190 °C; for the screw of layer C, the temperature is set as follows: Zone 1: 168 °C, Zone 2: 170 °C, Zone 3: 172 °C, Zone 4: 175 °C; the die head temperature is set at 175 °C.

[0070] Example 2

[0071] Example 2 of the present invention provides a multi-layer composite hot melt adhesive film and its preparation method. The specific implementation manner is the same as that of Example 1, except that the polyolefin resin is polyethylene, the polyethylene is maleic anhydride graft-modified polyethylene, the melt mass flow rate (2.16 kg, 190 °C) is 9.2 g / 10 min, the grade is ADMERTM MF528, and it is sourced from Mitsui Chemicals; the hardness of the polyester-based thermoplastic polyurethane elastomer is 85A, and the grade is Lubrizol's 58271; the long-chain nylon is PA612, and the grade of the PA612 is Swiss EMSD1523A; in the parameter settings of the three screws of the three-layer coextrusion blown film machine, the die head temperature is set at 185 °C.

[0072] Example 3

[0073] Example 3 of the present invention provides a multi-layer composite hot melt adhesive film and its preparation method. The specific implementation manner is the same as that of Example 1, except that the thickness of the polyolefin hot melt adhesive film is 0.005 mm, the thickness of the modified polyamide film is 0.005 mm, and the thickness of the polyurethane hot melt adhesive film is 0.005 mm.

[0074] Example 4

[0075] Example 4 of the present invention provides a multi-layer composite hot melt adhesive film and its preparation method. The specific implementation manner is the same as that of Example 1, except that the thickness of the polyolefin hot melt adhesive film is 0.05 mm, the thickness of the modified polyamide film is 0.05 mm, and the thickness of the polyurethane hot melt adhesive film is 0.05 mm.

[0076] Comparative Example 1

[0077] Comparative Example 1 of the present invention provides a multi-layer composite hot melt adhesive film and a preparation method thereof. The specific implementation is the same as that of Example 1, except that the B layer is replaced with a maleic anhydride grafted SEBS film. The raw material for preparing the maleic anhydride grafted SEBS film is maleic anhydride grafted SEBS with the brand name of Kraton MD6186. The preparation method of the multi-layer composite hot melt adhesive film includes the following steps: dehumidifying and drying the raw material of the B layer at 60 °C for 5 h; stirring and mixing the raw material of the C layer and then dehumidifying and drying it at 70 °C for 5 h; putting the raw materials of the A layer, B layer, and C layer into three screws of a three-layer co-extrusion blown film machine, and obtaining a multi-layer composite hot melt adhesive film after co-extrusion into a film. The parameter settings of the three screws of the three-layer co-extrusion blown film machine include: the temperature setting of the A layer screw: 160 °C in zone 1, 163 °C in zone 2, 168 °C in zone 3, 168 °C in zone 4; the temperature setting of the B layer screw: 175 °C in zone 1, 180 °C in zone 2, 185 °C in zone 3, 190 °C in zone 4; the temperature setting of the C layer screw: 168 °C in zone 1, 170 °C in zone 2, 172 °C in zone 3, 175 °C in zone 4; the die head temperature setting is 185 °C.

[0078] Comparative Example 2

[0079] Comparative Example 2 of the present invention provides a multi-layer composite hot melt adhesive film and a preparation method thereof. The specific implementation is the same as that of Example 1, except that the B layer is replaced with a blend modified film. The raw materials for preparing the blend modified film, by weight, include 50 parts of maleic anhydride grafted SEBS and 50 parts of polyester-based thermoplastic polyurethane elastomer. The brand name of the maleic anhydride grafted SEBS is Kraton MD6186, and the brand name of the polyester-based thermoplastic polyurethane elastomer is HF-3H85A, which is sourced from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd.

[0080] The preparation method of the multi-layer composite hot melt adhesive film includes the following steps: preparing B layer granular materials and dehumidifying and drying them at 60 °C for 5 h; stirring and mixing the raw material of the C layer and then dehumidifying and drying it at 70 °C for 5 h; putting the raw materials of the A layer, B layer granular materials, and C layer into three screws of a three-layer co-extrusion blown film machine, and obtaining a multi-layer composite hot melt adhesive film after co-extrusion into a film.

[0081] The preparation method of the B layer granular materials is as follows: stirring and mixing maleic anhydride grafted SEBS and polyester-based thermoplastic polyurethane elastomer to obtain a mixture, adding the mixture to a twin-screw extruder, extruding, pelletizing, cutting, and drying to obtain the B layer granular materials.

[0082] The process parameter settings of the twin-screw extruder are: 160 °C in zone 1, 165 °C in zone 2, 170 °C in zone 3, 175 °C in zone 4.

[0083] The parameter settings of the three screws of the three-layer coextrusion blown film machine are as follows. For the screw of layer A, the temperature settings are: zone 1: 160 °C, zone 2: 163 °C, zone 3: 168 °C, zone 4: 168 °C; for the screw of layer B, the temperature settings are: zone 1: 175 °C, zone 2: 180 °C, zone 3: 185 °C, zone 4: 185 °C; for the screw of layer C, the temperature settings are: zone 1: 168 °C, zone 2: 170 °C, zone 3: 172 °C, zone 4: 175 °C; the die head temperature is set at 180 °C.

[0084] Comparative Example 3

[0085] Comparative Example 3 of the present invention provides a multi-layer composite hot melt adhesive film and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the layer B is replaced with a blend modified film. The preparation raw materials of the blend modified film, by weight, include 50 parts of polyolefin resin, 50 parts of polyester-based thermoplastic polyurethane elastomer, and 4 parts of maleic anhydride monomer. The polyolefin resin has the trade name PRIMACOR TM 3003, sourced from SK Functional Polymers; the polyester-based thermoplastic polyurethane elastomer has the trade name HF-3H85A, sourced from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd.

[0086] The preparation method of the multi-layer composite hot melt adhesive film includes the following steps: preparing the granular material of layer B and carrying out dehumidifying and drying at 60 °C for 5 h; stirring and mixing the raw materials of layer C and carrying out dehumidifying and drying at 70 °C for 5 h; putting the raw materials of layer A, the granular material of layer B, and the raw materials of layer C into the three screws of the three-layer coextrusion blown film machine, and obtaining the multi-layer composite hot melt adhesive film after coextrusion into a film.

[0087] The preparation method of the granular material of layer B is: stirring and mixing the polyolefin resin, the polyester-based thermoplastic polyurethane elastomer, and the maleic anhydride monomer to obtain a mixture, adding the mixture into a twin-screw extruder, extruding, pelletizing, cutting, and drying to obtain the granular material of layer B.

[0088] The process parameter settings of the twin-screw extruder are: zone 1: 160 °C, zone 2: 165 °C, zone 3: 170 °C, zone 4: 170 °C.

[0089] The parameter settings of the three screws of the three-layer coextrusion blown film machine are as follows. For the screw of layer A, the temperature settings are: zone 1: 160 °C, zone 2: 163 °C, zone 3: 168 °C, zone 4: 168 °C; for the screw of layer B, the temperature settings are: zone 1: 165 °C, zone 2: 170 °C, zone 3: 175 °C, zone 4: 175 °C; for the screw of layer C, the temperature settings are: zone 1: 168 °C, zone 2: 170 °C, zone 3: 172 °C, zone 4: 175 °C; the die head temperature is set at 180 °C.

[0090] Comparative Example 4

[0091] Comparative Example 4 of the present invention provides a multi-layer composite hot melt adhesive film and a preparation method thereof. The specific implementation is the same as that of Example 1, except that it includes an A layer and a C layer, where: the A layer is a polyolefin-based hot melt adhesive film, and the C layer is a polyurethane-based hot melt adhesive film. The thickness of the polyolefin-based hot melt adhesive film is 0.025 mm, and the thickness of the polyurethane-based hot melt adhesive film is 0.025 mm. The preparation raw materials of the polyolefin-based hot melt adhesive film include polyolefin resin, and the polyolefin resin is the TPEE material HP4091 of Shanghai Yidan New Materials Co., Ltd. The preparation raw materials of the polyurethane-based hot melt adhesive film are the same as those of Example 1.

[0092] The preparation method of the multi-layer composite hot melt adhesive film includes the following steps: dehumidifying and drying the raw materials of the A layer at 60 °C for 5 h; stirring and mixing the raw materials of the C layer and then dehumidifying and drying them at 70 °C for 5 h; putting the raw materials of the A layer and the raw materials of the C layer into two screws of a double-layer co-extrusion blown film machine, and obtaining the multi-layer composite hot melt adhesive film after co-extrusion into a film.

[0093] The parameter settings of the two screws of the double-layer co-extrusion blown film machine include: the temperature setting of the A layer screw: 160 °C in zone 1, 163 °C in zone 2, 168 °C in zone 3, 168 °C in zone 4; the temperature setting of the C layer screw: 165 °C in zone 1, 170 °C in zone 2, 175 °C in zone 3, 175 °C in zone 4; the die head temperature is set at 175 °C.

[0094] Comparative Example 5

[0095] Comparative Example 5 of the present invention provides a multi-layer composite hot melt adhesive film and a preparation method thereof. The specific implementation is the same as that of Example 1, except that it includes an A layer and a C layer, where: the A layer is a polyolefin-based hot melt adhesive film, and the C layer is a polyurethane-based hot melt adhesive film. The thickness of the polyolefin-based hot melt adhesive film is 0.025 mm, and the thickness of the polyurethane-based hot melt adhesive film is 0.025 mm. The preparation raw materials of the polyolefin-based hot melt adhesive film include polyolefin resin, and the polyolefin resin includes 50 parts by weight of the TPEE material HP4091 of Shanghai Yidan New Materials Co., Ltd. and 50 parts by weight of the EAA material PRIMACOR TM 3003 of SK; the preparation raw materials of the polyurethane-based hot melt adhesive film are the same as those of Example 1.

[0096] The preparation method of the multi-layer composite hot melt adhesive film includes the following steps: preparing the granular materials of the A layer and dehumidifying and drying them at 60 °C for 5 h; stirring and mixing the raw materials of the C layer and then dehumidifying and drying them at 70 °C for 5 h; putting the raw materials of the A layer and the raw materials of the C layer into two screws of a double-layer co-extrusion blown film machine, and obtaining the multi-layer composite hot melt adhesive film after co-extrusion into a film.

[0097] The preparation method of the granular material of layer A is as follows: Mix 50 parts by weight of the TPEE material HP4091 from Shanghai Yidan New Materials Co., Ltd. and 50 parts by weight of the EAA material PRIMACOR from SK TM 3003 to obtain a mixture. Add the mixture to a twin-screw extruder, extrude and pelletize, cut the pellets, and dry them to obtain the granular material of layer A. The process parameters of the twin-screw extruder are set as follows: Zone 1: 155 °C, Zone 2: 160 °C, Zone 3: 165 °C, Zone 4: 165 °C.

[0098] The parameter settings of the two screws of the double-layer co-extrusion blown film machine include: For the screw temperature setting of layer A: Zone 1: 160 °C, Zone 2: 163 °C, Zone 3: 168 °C, Zone 4: 168 °C; For the screw temperature setting of layer C: Zone 1: 165 °C, Zone 2: 170 °C, Zone 3: 175 °C, Zone 4: 175 °C; The die head temperature is set at 175 °C.

[0099] Performance testing

[0100] Perform the various tests in Table 1 on the multi-layer composite hot melt adhesive films obtained in the examples and comparative examples. See Table 1 for the test standards and test results.

[0101] Table 1

[0102]

[0103]

[0104] Analyzing the results in Table 1, it can be seen that:

[0105] 1. Compared with Example 1, in Example 3, the thickness of each layer is relatively thin, 0.005 mm, and the overall thickness is 0.015 mm. It can bond with metal and TPU, but the peel strength is insufficient; Compared with Example 1, in Example 3, the thickness of each layer is relatively thick, 0.05 mm, and the overall thickness is 0.15 mm. Increasing the hot pressing temperature, time, and pressure can achieve a better bonding effect, but the efficiency is reduced and the cost is too high, which is not suitable.

[0106] 2. The results of Comparative Examples 1-5 show that: For polyolefin hot melt adhesive materials, maleic anhydride grafted SEBS, TPU hot melt adhesive materials, and TPEE hot melt adhesive materials, after various combinations of pelletization and then made into films, it is still impossible to bond both metal and TPU materials while ensuring a high interlayer peel strength.

[0107] 3. Only maleic anhydride grafted modified PA612, PA12, PA1212, PA11 materials and polyolefin hot melt adhesive films and TPU all have good compatibility, high bonding strength, and are suitable intermediate layer materials. Using it as the intermediate layer, polyolefin hot melt adhesive films and TPU hot melt adhesive films can be made into three-layer films, one side can bond polar materials, and the other side can bond non-polar materials.

Claims

1. A multi-layer composite hot melt adhesive film, characterized in that: The invention comprises at least layer A, layer B and layer C, wherein layer A and layer C are compounded by layer B, wherein layer A is a polyolefin hot melt adhesive film, layer B is a modified polyamide film, and layer C is a polyurethane hot melt adhesive film; the raw materials for preparing the modified polyamide film, by weight, at least comprise: 80-120 parts of long carbon chain nylon, 5-50 parts of polystyrene, 0.1-8 parts of maleic anhydride monomer, 0.1-1 parts of peroxide, and 0.5-2 parts of solvent, and the number of carbon atoms in the long carbon chain nylon is ≥10.

2. The multi-layer composite hot melt adhesive film according to claim 1, characterized in that: The raw materials for preparing the polyolefin hot melt adhesive film include polyolefin resin; the raw materials for preparing the polyurethane hot melt adhesive film include thermoplastic polyurethane resin.

3. The multi-layer composite hot melt adhesive film according to claim 2, characterized in that: The thickness of the A layer, the B layer and the C layer are all in the range of 0.003 to 0.1 mm.

4. The multi-layer composite hot melt adhesive film according to claim 2, characterized in that: The melting point of the long carbon chain nylon is ≤220°C.

5. The multi-layer composite hot melt adhesive film according to claim 4, characterized in that: The long carbon chain nylon is selected from at least one of modified or unmodified PA12, PA1212, PA11 or PA612.

6. The multi-layer composite hot melt adhesive film according to claim 2, characterized in that: The polyolefin resin is selected from at least one of polyethylene, ethylene-vinyl acetate copolymer, ethylene propylene diene monomer rubber and ethylene acrylic acid copolymer.

7. The multi-layer composite hot melt adhesive film according to claim 2, characterized in that: The polyurethane resin is a thermoplastic polyurethane elastomer.

8. The multi-layer composite hot melt adhesive film according to claim 7, characterized in that: The melting point of the thermoplastic polyurethane elastomer is in the range of 60-180°C.

9. A method for preparing a multilayer composite hot melt adhesive film according to any one of claims 2 to 8, characterized in that: The method comprises at least the following steps: preparing layer A, layer B and layer C respectively, and then heat-pressing and bonding the layers A, B and C, or preparing the raw materials of layer A, layer B and layer C through three-layer co-extrusion equipment.

10. An application of the multi-layer composite hot melt adhesive film according to any one of claims 1 to 8, characterized in that: It is used for compounding between metal and at least one polar material among polycarbonate, acrylonitrile-butadiene-styrene plastic, thermoplastic polyurethane or glass fiber reinforced material.

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