Heat-resistant adhesive composition for multilayer pipe as well as preparation method and application of heat-resistant adhesive composition

Abstract

The invention discloses a heat-resistant adhesive composition for a multilayer pipe as well as a preparation method and application of the heat-resistant adhesive composition, and relates to the field of adhesive materials. The invention relates to a heat-resistant adhesive composition for a multilayer pipe. The heat-resistant adhesive composition comprises the following raw materials in percentage by weight: 20-30% of nylon powder; 40%-50% of a polypropylene graft; 5%-12% of polypropylene; 3%-8% of a polyolefin-based compatilizer; 10%-15% of a toughening agent; 0.2%-0.5% of a lubricant; 0.4%-0.7% of an antioxidant; wherein the polypropylene graft is selected from one or more of maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene, itaconic anhydride grafted polypropylene and methyl methacrylate grafted polypropylene, and the grafting rate of the polypropylene graft is 0.3%-0.5%. The adhesive composition prepared by the invention has good bonding strength and heat resistance, and can avoid the problems of poor bonding and performance degradation of a multi-layer pipe caused by softening of the adhesive in the forming process of the pipe.

Description

Technical Field

[0001] This invention relates to the field of adhesive materials, and in particular to a heat-resistant adhesive composition for multilayer pipes, its preparation method, and its application. Background Technology

[0002] With the development of the new energy vehicle industry, battery safety and efficiency have become core issues. Battery cooling systems ensure battery safety and improve energy conversion efficiency, making them a crucial component for extending battery life in new energy vehicles. Battery cooling systems typically employ multi-layer tubes, whose design offers excellent thermal insulation, hydrolysis resistance, and strength, thus making them widely used in cooling systems.

[0003] In multilayer tube systems for battery cooling, the outer layer tubes are often made of nylon to ensure flexibility and corrosion resistance. The middle or inner layer tubes are often made of polypropylene to ensure hydrolysis resistance and reduce weight. Adhesive materials are used for bonding and fixing between the outer and middle layers, and between the middle and inner layers.

[0004] Most adhesive materials on the market use polypropylene grafts, which have problems with poor heat resistance and poor long-term stability. Under extreme working conditions, adhesive materials are also prone to aging, softening or failure, which affects the service life of the entire stable system and threatens the overall safety of the battery pack.

[0005] Faced with the ever-growing demand in the new energy market, there is an urgent need for an adhesive composition that can improve the overall efficiency of the battery cooling system, has good bonding strength and heat resistance, avoid the problem of poor bonding and performance degradation of multilayer tubes due to adhesive softening during the tube molding process, and reduce maintenance costs. Summary of the Invention

[0006] To address the aforementioned issues, this application provides a multilayer heat-resistant adhesive composition for pipes, its preparation method, and its application.

[0007] This application provides a multilayer heat-resistant adhesive composition for pipes, its preparation method, and its application, using the following technical solution: In a first aspect, this application discloses a heat-resistant adhesive composition for multilayer tubes, comprising the following raw materials by weight percentage: 20%-30% nylon powder; 40%-50% polypropylene graft; Polypropylene 5%-12%; 3%-8% polyolefin-based compatibilizer; Toughening agent 10%-15%; Lubricant 0.2%-0.5%; Antioxidant content: 0.4%-0.7%; The polypropylene graft material is selected from one or more of maleic anhydride-grafted polypropylene, acrylic acid-grafted polypropylene, itaconic anhydride-grafted polypropylene, and methyl methacrylate-grafted polypropylene, and the grafting rate of the polypropylene graft material is 0.3%-0.5%.

[0008] By adopting the above technical solution, nylon powder is added to the adhesive composition. The anhydrides and carboxyl groups in the polypropylene graft can react with the amide groups in the nylon powder, achieving blending of nylon powder, polypropylene graft, and polypropylene. The polyolefin compatibilizer promotes the compatibility between the polar component nylon powder and the non-polar polymer polypropylene, which is beneficial to improving interfacial bonding and adhesive strength. The addition of the toughening agent can form a dispersed phase structure, improving toughness and impact resistance. When the adhesive composition is used for bonding between multilayer pipes, the addition of nylon powder and polypropylene, which are made of the same material as the pipe, facilitates compatibility and bonding with the pipe. The groups in the polypropylene graft and the polyolefin compatibilizer that react with nylon enhance the adhesive strength with the nylon pipe.

[0009] Through specific raw material ratios, the adhesive composition possesses excellent heat resistance and bonding strength. Cooling systems using this adhesive material can operate normally at higher temperatures. During the molding process of multilayer tubes, it can prevent poor adhesion and performance degradation caused by adhesive softening, thereby improving the long-term stability of multilayer tubes.

[0010] Optionally, the polyolefin-based compatibilizer is prepared from the following raw materials in parts by weight: 100 parts of matrix resin, selected from one or more of PP, POE, and HDPE; 4-9 parts of grafting monomer, selected from one or more of maleic anhydride, glycidyl methacrylate, 2-hydroxyethyl methacrylate, and 3-isopropenyl-α,α-dimethylbenzyl-isocyanate; 2-5 parts of monomers, styrene is selected; The initiator is 0.1-0.3 parts, and one or more of diethylphenylpropene peroxide and di-tert-butyl peroxide are selected.

[0011] By adopting the above technical solution, the polyolefin matrix resin is modified by melt grafting, and groups that can react with nylon are introduced into the matrix resin, thereby achieving high adhesion between the nylon outer layer and the polypropylene layer. The addition of styrene comonomer increases the grafting rate, thus preparing a compatibilizer that can promote the compatibility of nylon powder and polypropylene.

[0012] Optionally, the polyolefin-based compatibilizer is prepared from the following raw materials in parts by weight: 100 parts POE resin; 3-7 parts 2-hydroxyethyl methacrylate; 2-4 parts 3-isopropenyl-α,α-dimethylbenzyl-isocyanate; 2-4 parts styrene; and 0.15-0.3 parts diethylstyrene peroxide.

[0013] By adopting the above technical solution, a specific combination of polyolefin-based compatibilizers was selected. After grafting, isocyanate groups and hydroxyl groups were introduced into the POE resin. During melt blending and bonding, they can chemically react with the amino groups of nylon, thereby further improving the compatibility of the system.

[0014] Optionally, the polypropylene graft is a mixture of maleic anhydride-grafted polypropylene and methyl methacrylate-grafted polypropylene in a weight ratio of (1.4-1.8):1.

[0015] By adopting the above technical solution, maleic anhydride-grafted polypropylene provides anhydride groups, which can react with the amino groups of nylon, significantly improving the interfacial bonding strength; in addition to introducing carboxyl groups, the addition of methacrylic acid-grafted polypropylene can also improve the high temperature resistance and aging resistance of the adhesive layer, which is beneficial for high temperature bonding, thereby improving high temperature resistance while ensuring bonding strength.

[0016] Optionally, the toughening agent is selected from one or more of ethylene propylene diene monomer (EPDM) rubber, liquid nitrile rubber, and ethylene-vinyl acetate copolymer.

[0017] Optionally, the lubricant is selected from one or more of stearic acid and paraffin, and the antioxidant is selected from one or more of antioxidant 186 and antioxidant 1010.

[0018] Secondly, this application provides a method for preparing a heat-resistant adhesive composition for multilayer pipes, comprising the following steps: mixing nylon powder, polypropylene graft and polypropylene evenly, adding polyolefin-based compatibilizer, toughening agent, lubricant and antioxidant, and continuing to stir until fully dispersed to form a mixture; The mixture is added to a twin-screw extruder for melt mixing to form a continuous phase structure. The main machine speed for melt mixing is set at 250-300 r / min and the temperature is 215-235℃. After the continuous phase structure is cooled and cured, it is granulated by a pelletizer to obtain a multilayer heat-resistant adhesive composition for pipes.

[0019] By adopting the above technical solution and controlling the temperature of melt mixing, a uniformly dispersed adhesive composition with strong impact resistance can be obtained.

[0020] Optionally, the polyolefin-based compatibilizer is prepared by the following steps: The matrix resin, graft monomer, comonomer and initiator are thoroughly mixed. The uniformly mixed material is then subjected to a grafting reaction in a twin-screw extruder in a molten state. The extruder is set at a temperature of 190-210℃. After traction, cooling and pelleting, the grafted product is obtained. The reaction product was placed in a three-necked flask containing xylene and heated under reflux for 2-2.5 hours. The mixture was then filtered while hot, and the filtrate was poured into acetone to settle for 10-12 hours. After filtration, the mixture was washed with acetone, and the precipitate obtained by filtration was placed in a vacuum drying oven at 60-80°C for 24 hours to obtain a polyolefin-based compatibilizer.

[0021] By adopting the above technical solution, after obtaining the melt grafted product, unreacted grafted monomers are removed by purification, and the grafting rate is high.

[0022] Thirdly, this application discloses the application of a heat-resistant adhesive composition for multilayer tubes in the bonding of multilayer tube materials in the cooling system of new energy vehicle batteries.

[0023] In summary, this application has the following beneficial effects: 1. Nylon powder is added to the adhesive composition. The anhydrides and carboxyl groups in the polypropylene graft react with the amide groups of nylon, achieving blending of nylon powder, polypropylene graft, and polypropylene. A polyolefin compatibilizer promotes the compatibility between the polar component nylon and the non-polar polymer polypropylene, which is beneficial for improving interfacial bonding and adhesive strength. The addition of a toughening agent forms a dispersed phase structure, improving toughness and impact resistance. When the adhesive composition is used for bonding multilayer pipes, the addition of nylon powder and polypropylene, which are made of the same material as the pipe, facilitates compatibility and bonding with the pipe. The groups in the polypropylene graft and the polyolefin compatibilizer that react with nylon further enhance the adhesive strength with the nylon pipe.

[0024] Through specific raw material ratios, the adhesive composition possesses excellent heat resistance and bonding strength. Cooling systems using this adhesive material can operate normally at higher temperatures. During the molding process of multilayer tubes, it can prevent poor adhesion and performance degradation caused by adhesive softening, thereby improving the long-term stability of multilayer tubes.

[0025] 2. The polyolefin matrix resin is modified by melt grafting, introducing groups that can react with nylon into the matrix resin, thereby achieving high adhesion between the nylon outer layer and the polypropylene layer. The addition of styrene comonomer increases the grafting rate, thus preparing a compatibilizer that can promote the compatibility of nylon and polypropylene. Detailed Implementation

[0026] The present application will be further described in detail below with reference to Examples 1-8 and Comparative Examples 1-2.

[0027] Preparation Example Preparation Example 1 A polyolefin-based compatibilizer is prepared from the following raw materials: 100 parts of matrix resin, specifically PP; Four parts of graft monomer, specifically maleic anhydride; Two monomers were used, specifically styrene. 0.1 parts of initiator, specifically diethylphenylpropene peroxide.

[0028] Polyolefin-based compatibilizers are prepared through the following steps: The matrix resin, graft monomer, comonomer and initiator are thoroughly mixed. The uniformly mixed material is then subjected to a grafting reaction in a twin-screw extruder in a molten state. The extruder is set at 190°C. After traction, cooling and pelleting, the grafted product is obtained. The reaction product was placed in a three-necked flask containing xylene and heated under reflux for 2 hours. The mixture was then filtered while hot using a Buchner funnel. The filtrate was poured into acetone and allowed to settle for 10 hours. After filtration, the precipitate was washed multiple times with acetone. The filtered precipitate was then dried in a vacuum drying oven at 60°C for 24 hours to obtain a polyolefin-based compatibilizer.

[0029] Preparation Example 2 A polyolefin-based compatibilizer is prepared from the following raw materials: 100 parts of matrix resin, specifically HDPE; Nine parts of graft monomer, specifically glycidyl methacrylate; A total of 5 parts of monomers were used, specifically styrene; 0.3 parts of initiator, specifically di-tert-butyl peroxide.

[0030] Polyolefin-based compatibilizers are prepared through the following steps: The matrix resin, graft monomer, comonomer and initiator are thoroughly mixed. The uniformly mixed material is then subjected to a grafting reaction in a twin-screw extruder in a molten state. The extruder is set at 210°C. After traction, cooling and pelleting, the grafted product is obtained. The reaction product was placed in a three-necked flask containing xylene and heated under reflux for 2.5 h. The mixture was then filtered while hot using a Buchner funnel. The filtrate was poured into acetone and allowed to settle for 12 h. After filtration, the precipitate was washed multiple times with acetone. The filtered precipitate was then placed in a vacuum drying oven and dried at 80 °C for 24 h to obtain a polyolefin-based compatibilizer.

[0031] Preparation Example 3 A polyolefin-based compatibilizer is prepared from the following raw materials: 100 parts of POE resin; 3 parts of 2-hydroxyethyl methacrylate; 2 parts of 3-isopropenyl-α,α-dimethylbenzyl-isocyanate; 2 parts styrene; 0.15 parts of diethylphenylpropene peroxide.

[0032] Polyolefin-based compatibilizers are prepared through the following steps: POE resin, 2-hydroxyethyl methacrylate, 3-isopropenyl-α,α-dimethylbenzyl-isocyanate, styrene and diethylstyrene peroxide are thoroughly mixed. The uniformly mixed material is then subjected to a grafting reaction in a twin-screw extruder in a molten state. The extruder is set at 210°C. After traction, cooling and pelleting, the grafted product is obtained. The reaction product was placed in a three-necked flask containing xylene and heated under reflux for 2.5 h. The mixture was then filtered while hot using a Buchner funnel. The filtrate was poured into acetone and allowed to settle for 12 h. After filtration, the precipitate was washed multiple times with acetone. The filtered precipitate was then placed in a vacuum drying oven and dried at 80 °C for 24 h to obtain a polyolefin-based compatibilizer.

[0033] Preparation Example 4 A polyolefin-based compatibilizer is prepared from the following raw materials: 100 parts of POE resin; 7 parts of 2-hydroxyethyl methacrylate; 4 parts of 3-isopropenyl-α,α-dimethylbenzyl-isocyanate; 4 parts styrene; 0.3 parts of diethylphenylpropene peroxide.

[0034] Polyolefin-based compatibilizers are prepared through the following steps: POE resin, 2-hydroxyethyl methacrylate, 3-isopropenyl-α,α-dimethylbenzyl-isocyanate, styrene and diethylstyrene peroxide are thoroughly mixed. The uniformly mixed material is then subjected to a grafting reaction in a twin-screw extruder in a molten state. The extruder is set at 200°C. After traction, cooling and pelleting, the grafted product is obtained. The reaction product was placed in a three-necked flask containing xylene and heated under reflux for 2 hours. The mixture was then filtered while hot using a Buchner funnel. The filtrate was poured into acetone and allowed to settle for 12 hours. After filtration, the precipitate was washed multiple times with acetone. The filtered precipitate was then dried in a vacuum drying oven at 70°C for 24 hours to obtain a polyolefin-based compatibilizer. Example

[0035] Example 1 This application discloses a heat-resistant adhesive composition for multilayer pipes used in battery cooling systems for new energy vehicles. Multilayer pipe designs are commonly used in the cooling pipes of battery cooling systems. The most common design uses an outer nylon pipe, with the middle and inner layers made of polypropylene. The heat-resistant adhesive composition is used for bonding and fixing the pipes together.

[0036] A heat-resistant adhesive composition for multilayer pipes, comprising the following raw materials in weight percentages: 20% nylon powder, specifically PA6 powder with a particle size of 200 mesh, purchased from Dongguan Hangyi Hot Melt Adhesive Co., Ltd. The polypropylene graft material was 43.8%, specifically maleic anhydride-grafted polypropylene with a grafting rate of 0.3%, purchased from Dongguan Xingyuan Chemical Co., Ltd. 12% polypropylene, specifically Yanshan Petrochemical B8101 polypropylene, purchased from Dongguan Qingchuan Plastics Co., Ltd. 8% polyolefin-based compatibilizer, specifically the polyolefin-based compatibilizer prepared in Preparation Example 1; Toughening agent 15%, specifically EPDM rubber; Lubricant 0.5%, specifically stearic acid; Antioxidant 0.7%, specifically antioxidant 1010.

[0037] The preparation method of the above-mentioned heat-resistant adhesive composition for multilayer pipes includes the following steps: Mix nylon powder, polypropylene grafts and polypropylene evenly, add polyolefin compatibilizer, toughening agent, lubricant and antioxidant, and continue stirring until fully dispersed to form a mixture; The mixture is added to a twin-screw extruder for melt mixing to form a continuous phase structure. The main machine speed for melt mixing is set at 250 r / min and the temperature is 215℃. After the continuous phase structure is cooled and cured, it is granulated by a pelletizer to obtain a multilayer heat-resistant adhesive composition for pipes.

[0038] Example 2 A heat-resistant adhesive composition for multilayer pipes, comprising the following raw materials in weight percentages: 30% nylon powder, specifically PA6 powder with a particle size of 200 mesh, purchased from Dongguan Hangyi Hot Melt Adhesive Co., Ltd. The polypropylene graft material is 45%, specifically acrylic acid grafted polypropylene with a grafting rate of 0.5%, purchased from Hangzhou Huizhi New Material Technology Co., Ltd. Polypropylene 10.4%, specifically Yanshan Petrochemical B8101 polypropylene, purchased from Dongguan Qingchuan Plastics Co., Ltd.; polyolefin compatibilizer 4%, specifically the polyolefin compatibilizer prepared in Preparation Example 1. Toughening agent 10%, specifically ethylene-vinyl acetate copolymer; Lubricant 0.2%, specifically paraffin wax; Antioxidant 0.4%, specifically antioxidant 168.

[0039] The preparation method of the above-mentioned heat-resistant adhesive composition for multilayer pipes includes the following steps: Mix nylon powder, polypropylene grafts and polypropylene evenly, add polyolefin compatibilizer, toughening agent, lubricant and antioxidant, and continue stirring until fully dispersed to form a mixture; The mixture is added to a twin-screw extruder for melt mixing to form a continuous phase structure. The main machine speed for melt mixing is set at 300 r / min and the temperature is 235℃. After the continuous phase structure is cooled and cured, it is granulated by a pelletizer to obtain a multilayer heat-resistant adhesive composition for pipes.

[0040] Example 3 A heat-resistant adhesive composition for multilayer pipes, comprising the following raw materials in weight percentages: 25% nylon powder, specifically PA6 powder with a particle size of 200 mesh, purchased from Dongguan Hangyi Hot Melt Adhesive Co., Ltd. The polypropylene graft material was 45%, specifically itaconic anhydride-grafted polypropylene with a grafting rate of 0.5%, purchased from Hangzhou Huizhi New Material Technology Co., Ltd. 9% polypropylene, specifically Yanshan Petrochemical B8101 polypropylene, purchased from Dongguan Qingchuan Plastics Co., Ltd. 7% polyolefin-based compatibilizer, specifically the polyolefin-based compatibilizer prepared in Preparation Example 2; Toughening agent 13.2%, specifically liquid nitrile rubber; Lubricant 0.3%, specifically stearic acid; Antioxidant 0.5%, specifically antioxidant 168.

[0041] The preparation method of the heat-resistant adhesive composition for multilayer pipes is the same as that in Example 1.

[0042] Example 4 The difference between this embodiment and Embodiment 1 is that the polyolefin-based compatibilizer in the adhesive composition raw materials is different.

[0043] The polyolefin-based compatibilizer used in this embodiment is the polyolefin-based compatibilizer prepared in Preparation Example 3.

[0044] The preparation method of the heat-resistant adhesive composition for multilayer pipes is the same as that in Example 1.

[0045] Example 5 The difference between this embodiment and Embodiment 1 is that the polyolefin-based compatibilizer in the adhesive composition raw materials is different.

[0046] In this embodiment, the polyolefin-based compatibilizer used is the polyolefin-based compatibilizer prepared in Preparation Example 4.

[0047] The preparation method of the heat-resistant adhesive composition for multilayer pipes is the same as that in Example 1.

[0048] Example 6 The difference between this embodiment and Embodiment 1 is that the polypropylene graft material in the adhesive composition raw materials is different.

[0049] In this embodiment, the polypropylene graft material is a mixture of maleic anhydride-grafted polypropylene and methyl methacrylate-grafted polypropylene in a weight ratio of 1.4:1. Specifically, it is 25.6% maleic anhydride-grafted polypropylene with a grafting rate of 0.3%, purchased from Dongguan Xingyuan Chemical Co., Ltd.; and 18.2% methyl methacrylate-grafted polypropylene with a grafting rate of 0.4%, purchased from Mitsubishi Chemical (Shanghai) Co., Ltd.

[0050] The preparation method of the heat-resistant adhesive composition for multilayer pipes is the same as that in Example 1.

[0051] Example 7 The difference between this embodiment and Embodiment 1 is that the polypropylene graft material in the adhesive composition raw materials is different.

[0052] In this embodiment, the polypropylene graft material is a mixture of maleic anhydride-grafted polypropylene and methyl methacrylate-grafted polypropylene in a weight ratio of 1.8:1. Specifically, it consists of 28.1% maleic anhydride-grafted polypropylene with a grafting rate of 0.3%, purchased from Dongguan Xingyuan Chemical Co., Ltd., and 15.7% methyl methacrylate-grafted polypropylene with a grafting rate of 0.4%, purchased from Mitsubishi Chemical (Shanghai) Co., Ltd.

[0053] The preparation method of the heat-resistant adhesive composition for multilayer pipes is the same as that in Example 1.

[0054] Example 8 The difference between this embodiment and Embodiment 1 is that the polyolefin-based compatibilizer and polypropylene graft in the adhesive composition raw materials are different.

[0055] The polyolefin-based compatibilizer used in this embodiment is the polyolefin-based compatibilizer prepared in Preparation Example 4; the polypropylene graft used in this embodiment is a mixture of maleic anhydride-grafted polypropylene and methyl methacrylate-grafted polypropylene in a weight ratio of 1.4:1, specifically 25.6% maleic anhydride-grafted polypropylene and 18.2% methyl methacrylate-grafted polypropylene.

[0056] Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 is that an equal mass of polypropylene grafted material is used instead of polyolefin-based compatibilizer in the raw materials of the adhesive composition.

[0057] The other components and preparation method of the adhesive composition are the same as in Example 1.

[0058] Comparative Example 2 The difference between this comparative example and Example 1 is that an equal mass of polypropylene is used instead of nylon powder in the raw materials of the adhesive composition.

[0059] The other components and preparation method of the adhesive composition are the same as in Example 1.

[0060] Performance testing The adhesive composition was used for bonding nylon / polypropylene composite pipes: On a three-layer co-extrusion pipe processing equipment, polypropylene was used as the inner layer, and the adhesive composition and nylon 12 were used as the outer layers. The temperatures of the nylon extruder were controlled at 210℃, the adhesive composition extruder at 230℃, and the polypropylene extruder at 190℃ to obtain a polypropylene / nylon 12 composite pipe through co-extrusion. The thickness of the polypropylene inner layer was 0.4-0.5 mm, the adhesive composition thickness was 0.1-0.2 mm, and the nylon outer layer thickness was 0.4-0.9 mm, with a total thickness of 1-1.5 mm. Peel test samples of 25 mm wide were cut along the pipe direction, and the 90° peel strength was tested at a tensile speed of 100 mm / min. The relevant data are shown in Table 1.

[0061] High-temperature resistance of adhesive composition: The shear strength of adhesive composition was tested according to standard GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)". Then the adhesive composition was aged at a constant high temperature of 200℃ for 7 days and the shear strength was re-measured. The relevant data are shown in Table 1.

[0062] Table 1 As shown in Table 1, the adhesive composition prepared in this application exhibits good interfacial bonding strength and high adhesive strength against both nylon and polypropylene materials. A comparison of shear strength data before and after high-temperature aging demonstrates the excellent high-temperature resistance of the adhesive composition prepared from the raw materials of this application. Therefore, the adhesive composition prepared in this application can meet the bonding requirements of multilayer tubes in battery cooling systems and exhibits good long-term stability.

[0063] Compared to Example 1, Examples 4-5 used polyolefin-based compatibilizers prepared from specific raw materials. Specific selections were made for the grafted monomers 2-hydroxyethyl methacrylate and 3-isopropenyl-α,α-dimethylbenzyl-isocyanate. By introducing more reactive hydroxyl and isocyanate groups into the compatibilizer, the compatibility of the adhesive composition was improved through chemical interaction with nylon, achieving a stronger chemical bond to nylon or polypropylene.

[0064] Compared to Example 1, Examples 6-7 involved the selection of specific proportions for the polypropylene grafts. Maleic anhydride-grafted polypropylene served as an important component, achieving chemical bonding through the reaction of anhydride groups and nylon amino groups. Methacrylic acid-grafted polypropylene introduced carboxyl groups, which also participated in the reaction. Furthermore, this improved the high-temperature resistance of the adhesive composition.

[0065] Compared to Example 1, Comparative Example 1 and Comparative Example 2 lacked polyolefin-based compatibilizer and nylon powder, respectively. Without polyolefin-based compatibilizer, the adhesive composition had poor compatibility and low bonding strength; without nylon powder, the adhesive composition had poor adhesion to nylon tubing.

[0066] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A heat-resistant adhesive composition for multilayer pipes, characterized in that, Including the following raw materials by weight percentage: 20%-30% nylon powder; 40%-50% polypropylene graft material; Polypropylene 5%-12%; Polyolefin-based compatibilizer 3%-8%; Toughening agent 10%-15%; Lubricant 0.2%-0.5%; Antioxidant content: 0.4%-0.7%; The polypropylene graft material is selected from one or more of maleic anhydride-grafted polypropylene, acrylic acid-grafted polypropylene, itaconic anhydride-grafted polypropylene, and methyl methacrylate-grafted polypropylene, and the grafting rate of the polypropylene graft material is 0.3%-0.5%.

2. The heat-resistant adhesive composition for multilayer pipes according to claim 1, characterized in that: The polyolefin-based compatibilizer is prepared from the following raw materials in parts by weight: 100 parts of matrix resin, selected from one or more of PP, POE, and HDPE; 4-9 parts of grafting monomer, selected from one or more of maleic anhydride, glycidyl methacrylate, 2-hydroxyethyl methacrylate, and 3-isopropenyl-α,α-dimethylbenzyl-isocyanate; 2-5 parts of monomers, styrene is selected; The initiator is 0.1-0.3 parts, and one or more of diethylphenylpropene peroxide and di-tert-butyl peroxide are selected.

3. The heat-resistant adhesive composition for multilayer pipes according to claim 2, characterized in that: The polyolefin-based compatibilizer is prepared from the following raw materials in parts by weight: 100 parts POE resin; 3-7 parts 2-hydroxyethyl methacrylate; 2-4 parts 3-isopropenyl-α,α-dimethylbenzyl-isocyanate; 2-4 parts styrene; and 0.15-0.3 parts diethylstyrene peroxide.

4. The heat-resistant adhesive composition for multilayer pipes according to claim 1, characterized in that: The polypropylene graft is a mixture of maleic anhydride-grafted polypropylene and methyl methacrylate-grafted polypropylene in a weight ratio of (1.4-1.8):

1.

5. The heat-resistant adhesive composition for multilayer pipes according to claim 1, characterized in that: The toughening agent is selected from one or more of EPDM rubber, liquid nitrile rubber, and ethylene-vinyl acetate copolymer.

6. The heat-resistant adhesive composition for multilayer pipes according to claim 1, characterized in that: The lubricant is selected from one or more of stearic acid and paraffin, and the antioxidant is selected from one or more of antioxidant 186 and antioxidant 1010.

7. A method for preparing a multilayer heat-resistant adhesive composition for pipes according to any one of claims 1-6, characterized in that, Includes the following steps: Mix nylon powder, polypropylene grafts and polypropylene evenly, add polyolefin compatibilizer, toughening agent, lubricant and antioxidant, and continue stirring until fully dispersed to form a mixture; The mixture is added to a twin-screw extruder for melt mixing to form a continuous phase structure. The main machine speed for melt mixing is set at 250-300 r / min and the temperature is 215-235℃. After the continuous phase structure is cooled and cured, it is granulated by a pelletizer to obtain a multilayer heat-resistant adhesive composition for pipes.

8. The method for preparing a multilayer heat-resistant adhesive composition for pipes according to claim 7, characterized in that: The polyolefin-based compatibilizer is prepared through the following steps: The matrix resin, graft monomer, comonomer and initiator are thoroughly mixed. The uniformly mixed material is then subjected to a grafting reaction in a twin-screw extruder in a molten state. The extruder is set at a temperature of 190-210℃. After traction, cooling and pelleting, the grafted product is obtained. The reaction product was placed in a three-necked flask containing xylene and heated under reflux for 2-2.5 hours. The mixture was then filtered while hot, and the filtrate was poured into acetone to settle for 10-12 hours. After filtration, the mixture was washed with acetone, and the precipitate obtained by filtration was placed in a vacuum drying oven at 60-80°C for 24 hours to obtain a polyolefin-based compatibilizer.

9. The application of the heat-resistant adhesive composition for multilayer tubes according to any one of claims 1-6 in the bonding of multilayer tube materials in the cooling system of new energy vehicle batteries.

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