Hot melt adhesive with high peel strength and preparation method thereof

Abstract

The invention relates to the technical field of hot melt adhesives, and discloses a hot melt adhesive with high peel strength and a preparation method thereof, and the hot melt adhesive comprises the following raw materials by weight: 35-55 parts of an ethylene-vinyl acetate copolymer; 20 to 35 parts by weight of polypropylene; 5-15 parts by weight of petroleum resin; 5-10 parts by weight of hydrogenated rosin resin; 1-3 parts by weight of a compatilizer; 0.5 to 1 part by weight of an antioxidant; 5-15 parts by weight of ethylene propylene diene monomer; and 0.1 to 0.5 part by weight of a reaction type compatilizer. A proper amount of crystalline polymer polyethylene is introduced into the formula of the hot melt adhesive, so that the temperature resistance and creep resistance of the hot melt adhesive can be improved, and the peel strength of the hot melt adhesive under a high-temperature or high-stress condition is improved; the introduction of the EPDM and the reactive compatibilizer significantly improves the compatibility of EVA and PP, effectively prevents layering, and improves the long-term stability of the hot melt adhesive.

Description

Technical Field

[0001] The present application relates to the technical field of hot melt adhesives, and mainly to a hot melt adhesive with high peel strength and a preparation method thereof. Background Art

[0002] Hot melt adhesives, as fast-acting and highly effective adhesives, are widely used in packaging, textiles, electronics, and other fields. Traditional hot melt adhesives are primarily based on amorphous polymers, such as ethylene-vinyl acetate (EVA) and styrene block copolymer (SBS). These amorphous polymers impart excellent flexibility and adhesion to hot melt adhesives, enabling them to quickly wet the adherend surface and form a bond. However, the shortcomings of amorphous hot melt adhesives are becoming increasingly prominent. First, they have poor temperature resistance and are prone to softening and creeping at high temperatures, resulting in a significant decrease in bond strength. For example, bond failure at high temperatures is a common problem in applications such as automotive interiors and outdoor advertising. Second, amorphous hot melt adhesives lack creep resistance and are prone to deformation under long-term loads, leading to bond loosening. For example, in applications such as heavy-duty packaging and structural bonding, bond reliability under long-term loads is crucial. To improve the temperature resistance and creep resistance of hot melt adhesives, a common strategy is to increase the polymer's molecular weight. However, increasing the molecular weight significantly increases the hot melt adhesive's melt viscosity, resulting in poor flowability and processability, making it difficult to meet the requirements of rapid coating and spraying processes. Therefore, how to improve the temperature resistance and creep resistance of hot melt adhesives without sacrificing fluidity and processability is a technical problem that needs to be solved urgently. At present, some studies have attempted to improve the performance of amorphous hot melt adhesives by adding fillers, crosslinking agents, etc. However, these methods often have problems such as poor dispersibility and difficulty in reaction control, making it difficult to achieve a comprehensive improvement in performance. Therefore, the development of a new hot melt adhesive formula that can significantly improve the temperature resistance and creep resistance while ensuring fluidity and processability has important research significance and application value.

[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a hot melt adhesive with high peel strength and a preparation method thereof, aiming to improve the temperature resistance and creep resistance of the hot melt adhesive.

[0005] The technical solution of this application is as follows: A hot melt adhesive with high peel strength, comprising the following raw materials in parts by weight: Ethylene-vinyl acetate copolymer: 35-55 parts by weight; Polypropylene: 20-35 parts by weight; Petroleum resin: 5-15 parts by weight; Hydrogenated rosin resin: 5-10 parts by weight; Compatibilizer: 1-3 parts by weight; Antioxidant: 0.5-1 parts by weight; EPDM rubber: 5-15 parts by weight; Reactive compatibilizer: 0.1-0.5 parts by weight; The compatibilizer is maleic anhydride grafted polypropylene, and the maleic anhydride grafting rate is 1-3%; The reactive compatibilizer is epoxy vinyl siloxane.

[0006] Introducing an appropriate amount of crystalline polymer polyethylene into the hot melt adhesive formula can improve the hot melt adhesive's temperature resistance and creep resistance, thereby increasing its peel strength under high temperature or high stress conditions. Furthermore, introducing a small amount of ethylene propylene diene monomer (EPDM) into the EVA / PP hot melt adhesive system. EPDM has excellent elasticity and weather resistance, which can improve the hot melt adhesive's flexibility and impact resistance. At the same time, the EPDM molecular chain contains a small amount of unsaturated double bonds, which can be blended or grafted with EVA and PP, improving the compatibility between the three and reducing the risk of delamination and precipitation. By using a reactive compatibilizer, a stronger chemical bond can be formed between EVA and PP, significantly improving compatibility, effectively preventing delamination, and improving the mechanical properties and stability of the hot melt adhesive.

[0007] The hot melt adhesive with high peel strength, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of 25-35% EVA and a melt index of 2.8-3.2 g / 10 min.

[0008] The hot melt adhesive with high peel strength, wherein the polypropylene is a homopolymer polypropylene resin with a melt index of 3-8 g / 10min.

[0009] In the hot melt adhesive with high peel strength, the petroleum resin is a C5 petroleum resin with a softening point of 90-120°C, and the hydrogenated rosin resin is a hydrogenated rosin resin with a softening point of 80-100°C.

[0010] In the hot melt adhesive with high peel strength, the antioxidant is antioxidant 1010 or antioxidant 1076.

[0011] The hot melt adhesive with high peel strength, wherein the ethylene content of the EPDM rubber is 50-70%, and the diene content is 3-8%.

[0012] A method for preparing the hot melt adhesive having high peel strength as described above, comprising the following steps: Raw material pretreatment: dry ethylene-vinyl acetate copolymer at 70-90℃ for 3-5 hours, and dry EPDM rubber at 70-90℃ for 3-5 hours; Melt blending: Add the dried ethylene-vinyl acetate copolymer and EPDM rubber to the No. 1 feed port of the twin-screw extruder, start the extruder to melt the ethylene-vinyl acetate copolymer and EPDM rubber, set the temperature of zone 1 to 100-120°C, the temperature of zones 2 to 5 to 150-170°C, and the screw speed to 150-250rpm; Feed in sequence: After the ethylene-vinyl acetate copolymer and EPDM rubber are completely melted, add polypropylene through the No. 2 feed port, then add petroleum resin, hydrogenated rosin resin, compatibilizer and antioxidant through the No. 3 feed port and continue mixing; Reaction and homogenization: Adjust the extruder temperature to 180-200°C, add the reactive compatibilizer through the No. 4 feed port, and increase the screw speed to 300-400 rpm to fully mix the components and allow the grafting reaction to occur; Cooling: The evenly mixed melt is extruded from the die into a rod shape, cooled to room temperature through a water cooling system, and cut into the required size.

[0013] Beneficial effects: This application can improve the temperature resistance and creep resistance of the hot melt adhesive by introducing an appropriate amount of crystalline polymer polyethylene into the hot melt adhesive formula, thereby improving its peel strength under high temperature or high stress conditions. At the same time, a compatibilizer is added to improve the compatibility between the crystalline polymer and the amorphous polymer, thereby improving the adhesion and fluidity of the hot melt adhesive. In addition, a small amount of ethylene propylene diene monomer rubber is introduced into the EVA / PP hot melt adhesive system. The EPDM molecular chain contains a small amount of unsaturated double bonds, which can be blended or grafted with EVA and PP to improve the compatibility between the three and reduce the risk of delamination and precipitation. In addition, by using a reactive compatibilizer, a stronger chemical bond can be formed between EVA and PP, significantly improving compatibility, effectively preventing delamination, and improving the mechanical properties and stability of the hot melt adhesive. DETAILED DESCRIPTION

[0014] To facilitate understanding of the present application, the present application lists the following examples. Those skilled in the art should understand that the examples are only provided to help understand the present application and should not be considered as specific limitations of the present application.

[0015] The present application also provides a hot melt adhesive with high peel strength, which comprises the following raw materials in parts by weight: Ethylene vinyl acetate copolymer (EVA): 35-55 parts by weight; Polypropylene (PP): 20-35 parts by weight; EPDM: 5-15 parts by weight; Petroleum resin: 5-15 parts by weight; Hydrogenated rosin resin: 5-10 parts by weight; Compatibilizer: 1-3 parts by weight; Reactive compatibilizer: 0.1-0.5 parts by weight; Antioxidant: 0.5-1 parts by weight.

[0016] This formulation uses EVA as the base resin, providing excellent adhesion and flexibility. PP, a crystalline polymer, improves the hot melt adhesive's temperature resistance and creep resistance, thereby enhancing its peel strength under high-temperature or high-stress conditions. Furthermore, the addition of a compatibilizer improves the compatibility between the crystalline and amorphous polymers, enhancing the adhesive's adhesion and fluidity. Both EVA and PP are commercially available, inexpensive, and economical.

[0017] Polypropylene has limited compatibility with ethylene-vinyl acetate copolymer, which may cause the hot melt adhesive to delaminate or precipitate during use, especially in high temperature or high humidity environments, affecting the bonding effect and long-term stability. In addition, although the addition of PP improves the temperature resistance, it may also cause the flexibility of the hot melt adhesive to decrease. It performs well when bonding hard materials, but is prone to cracking or debonding when bonding flexible materials or undergoing bending or torsional stress. Therefore, in the embodiment scheme of the present application, a small amount of ethylene propylene diene monomer rubber is introduced into the EVA / PP hot melt adhesive system. EPDM has good elasticity and weather resistance, which can improve the flexibility and impact resistance of the hot melt adhesive. At the same time, the EPDM molecular chain contains a small amount of unsaturated double bonds, which can be blended or grafted with EVA and PP to improve the compatibility between the three and reduce the risk of delamination and precipitation.

[0018] Although maleic anhydride grafted polypropylene can improve the compatibility of EVA and PP as a compatibilizer, its grafting rate and molecular weight have a greater impact on the compatibility effect. Therefore, in the embodiment scheme of the present application, epoxy vinyl siloxane is added as a reactive compatibilizer, which reacts with EVA and PP during the extrusion process to generate a copolymer in situ, thereby achieving a better compatibility effect. By adopting a reactive compatibilizer, a stronger chemical bond can be formed between EVA and PP, significantly improving the compatibility, effectively preventing stratification, and improving the mechanical properties and stability of the hot melt adhesive. At the same time, since the reaction occurs in situ during the extrusion process, the problem of excessive melt viscosity caused by excessive use of MAH-g-PP can be avoided, maintaining good fluidity and processability.

[0019] This embodiment scheme comprehensively considers factors such as compatibility, flexibility, and weather resistance, and comprehensively optimizes the hot melt adhesive formula by introducing EPDM and a reactive compatibilizer. EPDM serves as a toughening phase, and the unsaturated double bonds in its molecular chain can be blended or grafted with EVA and PP, improving the compatibility between the three and reducing the risk of delamination and precipitation. At the same time, EPDM has good elasticity and weather resistance, which can enhance the flexibility and impact resistance of the hot melt adhesive. Epoxy vinyl siloxane reacts with EVA and PP during the extrusion process to form a copolymer in situ, forming a stronger chemical bond between EVA and PP, significantly improving compatibility, effectively preventing delamination, and enhancing the mechanical properties and stability of the hot melt adhesive. Specifically, the epoxy group can react with the carboxyl group in EVA to form an ester bond, and the vinyl group can undergo a free radical addition reaction with the unsaturated bonds in PP to form a copolymer. These chemical reactions form a strong connection between EVA and PP, improving compatibility. MAH-g-PP is still present as an auxiliary compatibilizer to further enhance compatibility.

[0020] The vinyl acetate content of ethylene-vinyl acetate copolymer (EVA) can be 25-35%, and the melt index can be 2.8-3.2 g / 10 min. In the embodiment of the present application, the vinyl acetate content of ethylene-vinyl acetate copolymer is about 27%, and the melt index is 3.0 g / 10 min. Escorene UL00328 from ExxonMobil is used.

[0021] The polypropylene (PP) can be a homopolymer polypropylene resin with a melt index of 3-8 g / 10min. In the embodiments of this application, the polypropylene is a homopolymer polypropylene resin with a melt index of 3.0 g / 10min, using T30S from Sinopec. For polymers of the same structure, the melt index is inversely proportional to the molecular weight. A higher melt index indicates greater polymer melt fluidity and corresponds to a lower molecular weight.

[0022] The petroleum resin may be a C5 petroleum resin having a softening point of 90-120° C. In the embodiment of the present application, the softening point of the petroleum resin is 105° C. ± 5° C., and Puyang Hengtai R5110 is used. As a tackifier, petroleum resin can improve the wettability and bonding strength of the hot melt adhesive.

[0023] The hydrogenated rosin resin may have a softening point of 80-100° C. In the embodiment of the present application, the softening point of the hydrogenated rosin resin is 95-100° C., and JS-100L produced by Guangdong Hongtai New Materials Co., Ltd. is used.

[0024] Although petroleum resin can improve the wettability and bonding strength of hot melt adhesives, it is easy to volatilize or oxidize at high temperatures, resulting in a decrease in the performance of the hot melt adhesive and a pungent odor, which affects the user experience and environmental friendliness. In addition, the sources of petroleum resin are limited and the price fluctuates greatly, which is not conducive to reducing production costs and ensuring the stability of the supply chain. Therefore, in the present application scheme, a combination of petroleum resin and hydrogenated rosin resin is adopted. Hydrogenated rosin resin has better heat resistance and weather resistance, is not easy to volatilize or oxidize, can improve the long-term stability of hot melt adhesives, and reduce odor. At the same time, rosin resin is widely available and has a relatively stable price, which is conducive to reducing production costs and ensuring the stability of the supply chain.

[0025] The compatibilizer is maleic anhydride-grafted polypropylene, which can be polypropylene with a maleic anhydride grafting ratio of 1-3%. In the embodiments of this application, the maleic anhydride-grafted polypropylene is polypropylene with a maleic anhydride grafting ratio of 1-1.4%, using DuPont's Fusabond P353. The compatibilizer improves the compatibility between EVA and PP, preventing PP agglomeration in the EVA matrix, thereby enhancing the mechanical properties and stability of the hot melt adhesive. Maleic anhydride grafted onto the PP chains creates chemical bonding between the PP segments and the EVA segments, reducing interfacial tension and increasing compatibility.

[0026] The antioxidant may be antioxidant 1010 or antioxidant 1076. In the embodiment of the present application, the antioxidant is antioxidant 1010, which is BASF's antioxidant 1010. The function of the antioxidant is to prevent the hot melt adhesive from oxidative degradation during processing and use, thereby increasing its service life.

[0027] The ethylene content of EPDM rubber can be 50-70%, and the diene content can be 3-8%. In the embodiment of the present application, the ethylene content of EPDM rubber is 63%, and the diene content is 8%, and Vistalon 8780 from ExxonMobil is used.

[0028] The reactive compatibilizer is epoxy vinyl siloxane. In the embodiment of the present application, epoxy vinyl siloxane is Silquest A-186 produced by Momentive Advanced Materials Group.

[0029] In the present application, a method for preparing a hot melt adhesive with high peel strength is also provided, comprising the following steps: (1) Raw material pretreatment: Dry the EVA in a vacuum oven at 70-90°C for 3-5 hours to remove moisture and prevent bubbles from forming during extrusion; Dry the EPDM in a vacuum oven at 70-90°C for 3-5 hours to remove moisture.

[0030] (2) Melt blending: Add the dried EVA and EPDM into the No. 1 feed port of the twin-screw extruder, start the extruder, and melt the EVA and EPDM.

[0031] The temperature of zone 1 is set at 100-120°C, the temperature of zones 2 to 5 is set at 150-170°C, and the screw speed is set at 150-250rpm.

[0032] Adding EPDM and EVA together into feed port No. 1 and melt-blending EVA and EPDM first can improve the compatibility between the two and promote the subsequent dispersion of PP.

[0033] (3) Feed in sequence: After EVA and EPDM are completely melted, add PP through feed port No. 2, then add petroleum resin, hydrogenated rosin resin, compatibilizer and antioxidant through feed port No. 3 and continue mixing.

[0034] PP is added slowly and the feeding rate of PP is controlled to ensure that PP can be evenly dispersed in the EVA melt.

[0035] (4) Reaction and homogenization: Adjust the extruder temperature to 180-200 °C, add the reactive compatibilizer through the No. 4 feed port, and increase the screw speed to 300-400 rpm to fully mix the components and allow the grafting reaction to occur.

[0036] In step (4), a reactive compatibilizer is added through feed port No. 4. Increasing the extruder temperature and screw speed can promote the reaction between the reactive compatibilizer and EVA and PP, generating copolymers in situ, thereby improving compatibility and the mechanical properties and stability of the hot melt adhesive.

[0037] Preferably, a static mixer is installed at the end of the extruder to further improve mixing uniformity and reduce the agglomeration of PP in the EVA matrix, thereby improving the mechanical properties and stability of the hot melt adhesive.

[0038] (5) Cooling: The mixed melt is extruded from the die into a rod shape and cooled to room temperature through a water cooling system. Then, it is cut into hot melt adhesive sticks of the desired size.

[0039] (6) Packaging: The hot melt glue sticks are graded and screened to remove unqualified ones, and then packaged to obtain the finished products.

[0040] The present application is further described below through specific examples. Example 1:

[0041] The product formula is as follows: Ethylene vinyl acetate copolymer: 45 parts by weight (Escorene UL00328, ExxonMobil Corporation); Polypropylene: 30 parts by weight (T30S, Sinopec); EPDM: 10 parts by weight (Vistalon 8780, ExxonMobil); Petroleum resin: 7 parts by weight (R5110, Puyang Hengtai); Hydrogenated rosin resin: 8 parts by weight (JS-100L, Guangdong Hongtai New Materials Co., Ltd.); Compatibilizer maleic anhydride grafted polypropylene: 2 parts by weight (Fusabond P353, DuPont); Reactive compatibilizer epoxy vinyl siloxane: 0.3 parts by weight (Silquest A-186, Momentive Advanced Materials Group); Antioxidant 1010: 0.7 parts by weight (BASF).

[0042] The preparation method of the product is as follows: 1. Dry EVA and EPDM in a vacuum oven at 80°C for 4 hours to remove moisture.

[0043] 2. Add the dried EVA and EPDM to the No. 1 feed port of the twin-screw extruder, set the temperature of zone 1 to 100°C, the temperature of zones 2 to 5 to 150°C, and the screw speed to 200 rpm.

[0044] 3. After EVA and EPDM are completely melted, slowly add PP through feed port No. 2, then add petroleum resin, hydrogenated rosin resin, compatibilizer and antioxidant through feed port No. 3 and continue mixing.

[0045] 4. Adjust the extruder temperature to 190°C, add the reactive compatibilizer through the No. 4 feed port, and increase the screw speed to 400 rpm to fully mix the components.

[0046] 5. The evenly mixed melt is extruded from the die into a rod shape and cooled to room temperature through a water cooling system.

[0047] 6. Cut into required size to get hot melt glue stick. Example 2:

[0048] The product formula is as follows: Ethylene vinyl acetate copolymer: 40 parts by weight (Escorene UL00328, ExxonMobil); Polypropylene: 35 parts by weight (T30S, Sinopec); EPDM: 12 parts by weight (Vistalon 8780, ExxonMobil); Petroleum resin: 5 parts by weight (R5110, Puyang Hengtai); Hydrogenated rosin resin: 7 parts by weight (JS-100L, Guangdong Hongtai New Materials Co., Ltd.); Compatibilizer maleic anhydride grafted polypropylene: 1.5 parts by weight (Fusabond P353, DuPont); Reactive compatibilizer epoxy vinyl siloxane: 0.4 parts by weight (Silquest A-186, Momentive Advanced Materials Group); Antioxidant 1010: 0.6 parts by weight (BASF).

[0049] The preparation method of the product is the same as that in Example 1.

[0050] Comparative Example 1: The product formula is as follows: Ethylene vinyl acetate copolymer: 50 parts by weight (Escorene UL00328, ExxonMobil); Polypropylene: 30 parts by weight (T30S, Sinopec); Petroleum resin: 7 parts by weight (R5110, Puyang Hengtai); Hydrogenated rosin resin: 8 parts by weight (JS-100L, Guangdong Hongtai New Materials Co., Ltd.); Compatibilizer maleic anhydride grafted polypropylene: 3 parts by weight (Fusabond P353, DuPont); Antioxidant 1010: 0.7 parts by weight (BASF).

[0051] The preparation method of the product is as follows: 1. Dry the EVA in a vacuum oven at 80°C for 4 hours to remove moisture.

[0052] 2. Add the dried EVA to the No. 1 feed port of the twin-screw extruder, set the temperature of zone 1 to 120°C, the temperature of zones 2 to 5 to 160°C, and the screw speed to 200 rpm.

[0053] 3. After EVA is completely melted, slowly add PP through feed port No. 2, then add petroleum resin, hydrogenated rosin resin, compatibilizer and antioxidant through feed port No. 3 and continue mixing.

[0054] 4. Adjust the extruder temperature to 180°C and increase the screw speed to 300 rpm to fully mix the components.

[0055] 5. The evenly mixed melt is extruded from the die into a rod shape and cooled to room temperature through a water cooling system.

[0056] 6. Cut into required size to get hot melt glue stick.

[0057] Comparative Example 2: The product formula is as follows: Ethylene vinyl acetate copolymer: 55 parts by weight (Escorene UL00328, ExxonMobil Corporation); Polypropylene: 20 parts by weight (T30S, Sinopec); Petroleum resin: 5 parts by weight (R5110, Puyang Hengtai); Hydrogenated rosin resin: 7 parts by weight (JS-100L, Guangdong Hongtai New Materials Co., Ltd.); Compatibilizer maleic anhydride grafted polypropylene: 2 parts by weight (Fusabond P353, DuPont); Antioxidant 1010: 1 part by weight (BASF).

[0058] The preparation method of the product is the same as that of Control Example 1.

[0059] Comparative Example 3: A certain brand of EVA hot melt adhesive on the market (hereinafter referred to as the “control example”) was selected for performance testing.

[0060] The performance tests of the products prepared in Examples 1-2 and Comparative Examples 1-3 were performed as follows: Melt index was determined according to GB / T 3682.1-2018 at a test temperature of 190°C and a load of 2.16 kg. Softening point is determined according to GB / T 15332-2014; 180° peel strength is measured according to GB / T 2790-1995, the substrate is corrugated cardboard, and the test speed is 100mm / min; Shear strength was measured according to GB / T 7124-2008, with the substrate being corrugated cardboard; Heat resistance is measured according to ASTM D4498-00, maintaining the temperature at 70°C or 80°C for 24 hours and observing whether there is softening or flow. The tensile strength was determined according to GB / T 1040.1-2018 at a test speed of 50 mm / min; The elongation at break was determined in accordance with GB / T 1040.1-2018 at a test speed of 50 mm / min.

[0061] The performance test results of Examples 1-2 and Comparative Examples 1-3 are shown in Table 1.

[0062] Table 1 Melt index Softening point 180° peel strength Shear strength Heat resistance tensile strength Elongation at break Example 1 28g / 10min 105℃ 10 N / cm 1.0 MPa There is no significant change at 70℃ and 80℃ 12 MPa 400% Example 2 23g / 10min 110℃ 11 N / cm 1.1 MPa There is no significant change at 70℃ and 80℃ 13 MPa 450% Comparative Example 1 25g / 10min 95℃ 8 N / cm 0.8 MPa No significant change at 70℃ 9 MPa 310% Comparative Example 2 30g / 10min 90℃ 7 N / cm 0.7 MPa No significant change at 70℃ 10 MPa 340% Comparative Example 3 35g / 10min 85℃ 6 N / cm 0.6 MPa Slight softening at 70℃ - -

[0063] Compared with Comparative Examples 1-2 (without the addition of EPDM and reactive compatibilizer), the embodiment scheme of the present application has the following advantages: 1. Better compatibility: The introduction of EPDM and reactive compatibilizers significantly improves the compatibility of EVA and PP, effectively prevents delamination, and improves the long-term stability of hot melt adhesives.

[0064] 2. Higher flexibility and impact resistance: The addition of EPDM improves the flexibility and impact resistance of the hot melt adhesive, making it perform better in bonding flexible materials or bearing bending and torsional stress.

[0065] 3. Higher mechanical properties: The introduction of reactive compatibilizer improves the chemical bonding between EVA and PP, and improves the tensile strength and elongation at break of the hot melt adhesive.

[0066] 4. Better overall performance: This embodiment comprehensively considers factors such as compatibility, flexibility, weather resistance, and environmental friendliness, achieving comprehensive improvements in the performance of the hot melt adhesive. It is expected that peel strength, shear strength, temperature resistance, and long-term stability will all be significantly improved.

[0067] Compared with Comparative Example 3 (traditional EVA hot melt adhesive), the embodiment of the present application has the following advantages: 1. Higher temperature resistance: The addition of PP increases the melting point of the hot melt adhesive, allowing it to maintain good bonding strength at higher temperatures.

[0068] 2. Better anti-creep performance: The crystallinity of PP gives hot melt adhesive better anti-creep performance, making it less likely to deform under long-term load.

[0069] 3. Good fluidity and processability: By controlling the molecular weight and content of PP and adding a compatibilizer, the hot melt adhesive can be guaranteed to have good fluidity and processability to meet the process requirements of rapid coating, spraying, etc.

[0070] By comparing the above embodiments and control examples, it can be seen that the hot melt adhesive formula provided in this application effectively improves the temperature resistance, mechanical properties and long-term stability of the hot melt adhesive by introducing PP, EPDM, hydrogenated rosin resin and reactive compatibilizer, and all performance indicators are superior to existing commercially available EVA hot melt adhesive products.

[0071] It should be understood that the application of this application is not limited to the above examples. For ordinary technicians in this field, they can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of this application.

Claims

1. A hot melt adhesive with high peel strength, characterized in that: According to parts by weight, the following raw materials are included: Ethylene-vinyl acetate copolymer: 35-55 parts by weight; Polypropylene: 20-35 parts by weight; Petroleum resin: 5-15 parts by weight; Hydrogenated rosin resin: 5-10 parts by weight; Compatibilizer: 1-3 parts by weight; Antioxidant: 0.5-1 parts by weight; EPDM rubber: 5-15 parts by weight; Reactive compatibilizer: 0.1-0.5 parts by weight; The compatibilizer is maleic anhydride grafted polypropylene, and the maleic anhydride grafting rate is 1-3%; The reactive compatibilizer is epoxy vinyl siloxane.

2. The hot melt adhesive with high peel strength according to claim 1, characterized in that: The vinyl acetate content of the ethylene-vinyl acetate copolymer is 25-35%, and the melt index is 2.8-3.2 g / 10 min.

3. The hot melt adhesive with high peel strength according to claim 1, characterized in that: The polypropylene is a homopolymer polypropylene resin with a melt index of 3-8 g / 10min.

4. The hot melt adhesive with high peel strength according to claim 1, characterized in that: The petroleum resin is a C5 petroleum resin with a softening point of 90-120°C, and the hydrogenated rosin resin is a hydrogenated rosin resin with a softening point of 80-100°C.

5. The hot melt adhesive with high peel strength according to claim 1, characterized in that: The antioxidant is antioxidant 1010 or antioxidant 1076.

6. The hot melt adhesive with high peel strength according to claim 1, characterized in that: The ethylene content of the EPDM rubber is 50-70%, and the diene content is 3-8%.

7. A method for preparing a hot melt adhesive with high peel strength according to any one of claims 1 to 6, characterized in that: The following steps are involved: Raw material pretreatment: dry ethylene-vinyl acetate copolymer at 70-90℃ for 3-5 hours, and dry EPDM rubber at 70-90℃ for 3-5 hours; Melt blending: Add the dried ethylene-vinyl acetate copolymer and EPDM rubber to the No. 1 feed port of the twin-screw extruder, start the extruder to melt the ethylene-vinyl acetate copolymer, set the temperature of zone 1 to 100-120°C, the temperature of zones 2 to 5 to 150-170°C, and the screw speed to 150-250rpm; Feed in sequence: After the ethylene-vinyl acetate copolymer is completely melted, add polypropylene through feed port 2, then add petroleum resin, hydrogenated rosin resin and compatibilizer through feed port 3 and continue mixing; Reaction and homogenization: Adjust the extruder temperature to 180-200°C, add the reactive compatibilizer through the No. 4 feed port, and increase the screw speed to 300-400 rpm to fully mix the components and allow the grafting reaction to occur; Cooling: The evenly mixed melt is extruded from the die into a rod shape, cooled to room temperature through a water cooling system, and cut into the required size.