A high-temperature-resistant polyolefin hot melt adhesive and a preparation method thereof

Abstract

This invention relates to a high-temperature resistant polyolefin hot melt adhesive and its preparation method. The hot melt adhesive, by weight, comprises the following components: 25-40 parts polypropylene copolymer; 5-8 parts metallocene-catalyzed ethylene-octene copolymer; 1-2 parts nano-nucleating modifier; 3-8 parts reactive compatibilizer; 20-35 parts hyperbranched polyester-modified hydrogenated petroleum resin; 2-6 parts viscosity modifier; 0.5-1 part primary antioxidant; 0.2-0.4 parts auxiliary antioxidant; wherein the polypropylene copolymer is a copolymer of propylene and ethylene; the hyperbranched polyester-modified hydrogenated petroleum resin is prepared by the following method: hyperbranched polyester with a generation number of 3-5 and a molecular weight of 2000-5000 is melt-blended with hydrogenated petroleum resin at 180-200°C for 20-30 minutes, and cooled to obtain the hyperbranched polyester-modified hydrogenated petroleum resin, wherein the hyperbranched polyester grafting rate is 3-8 wt% and the melt index is 5-12 g / 10 min. Hot melt adhesives exhibit good performance in terms of high temperature resistance, bonding strength, low-temperature flexibility, storage stability, and thermal aging properties, which can meet the needs of various current applications.

Description

Technical Field

[0001] This invention relates to the field of hot melt adhesive technology, and in particular to a high-temperature resistant polyolefin hot melt adhesive and its preparation method. Background Technology

[0002] Polyolefin hot melt adhesives have advantages such as being solvent-free, environmentally friendly, fast curing speed, and wide bonding adaptability, and are widely used in automotive parts, electronics, high-end packaging and other fields.

[0003] As applications expand to high-temperature conditions, traditional polyolefin hot melt adhesives exhibit significant drawbacks: insufficient heat resistance, susceptibility to creep at high temperatures, and a substantial decrease in bond strength. Therefore, developing a polyolefin hot melt adhesive with superior high-temperature resistance has become a pressing technical challenge in this field. Summary of the Invention

[0004] Therefore, it is necessary to provide a high-temperature resistant polyolefin hot melt adhesive and its preparation method to address the problem of insufficient high-temperature resistance of polyolefin hot melt adhesives.

[0005] In one aspect, the present invention provides a high-temperature resistant polyolefin hot melt adhesive, comprising the following components by weight: 25-40 parts polypropylene copolymer; 5-8 parts of metallocene-catalyzed ethylene-octene copolymer; 1-2 parts of nano-nucleating modifier; 3-8 parts reactive compatibilizer; 20-35 parts of hyperbranched polyester modified hydrogenated petroleum resin; 2-6 parts viscosity modifier; 0.5-1 part of the main antioxidant; 0.2-0.4 parts of adjuvant antioxidant; Among them, the polypropylene copolymer is a copolymer of propylene and ethylene; Hyperbranched polyester modified hydrogenated petroleum resin is prepared by the following method: hyperbranched polyester with a generation number of 3-5 and a molecular weight of 2000-5000 is melt-blended with hydrogenated petroleum resin at 180-200℃ for 20-30 minutes, and then cooled to obtain hyperbranched polyester modified hydrogenated petroleum resin. The grafting rate of hyperbranched polyester is 3-8wt%, and the melt index is 5-12g / 10min.

[0006] In one embodiment, the nanonucleating modifier is a silane coupling agent modified nano-silica.

[0007] In one embodiment, the reactive compatibilizer is a maleic anhydride-grafted ethylene-octene copolymer.

[0008] In one embodiment, the mass ratio of polypropylene copolymer to hyperbranched polyester modified hydrogenated petroleum resin is 1:(1-1.2).

[0009] In one embodiment, the polypropylene copolymer has an ethylene content of 2-5 wt%, an isotacticity of 96%, and a melt index of 8-15 g / 10 min (230 °C, 2.16 kg).

[0010] In one embodiment, the metallocene-catalyzed ethylene-octene copolymer has a 1-octene content of 15-25 wt% and a melt index of 3-10 g / 10 min (190 °C, 2.16 kg).

[0011] In one embodiment, the viscosity modifier is Fischer-Tropsch wax and / or microcrystalline wax.

[0012] In one embodiment, the primary antioxidant is pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0013] In one embodiment, the auxiliary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:(1-2).

[0014] On the other hand, the present invention provides a method for preparing a high-temperature resistant polyolefin hot melt adhesive, for preparing any of the above-mentioned hot melt adhesives, comprising the following steps: A pre-dispersion was prepared by pre-mixing a nano-nucleating modifier with a metallocene-catalyzed ethylene-octene copolymer in a high-speed mixer. A mixture of polypropylene copolymer, metallocene-catalyzed ethylene-octene copolymer, reactive compatibilizer, and hyperbranched polyester-modified hydrogenated petroleum resin is prepared by mixing, adding pre-dispersant and main antioxidant, heating to 165-200℃, and stirring continuously for 2-4 minutes to obtain a melt. Add a viscosity modifier and an auxiliary antioxidant to the melt, control the temperature at 175-185℃, and stir for 10-15 minutes to form a mixture. The mixture is subjected to vacuum devolatilization, cooled, pelletized, and dried to obtain hot melt adhesive.

[0015] In one embodiment, in the melt preparation step, melting is performed using a twin-screw extruder, wherein polypropylene copolymer, metallocene-catalyzed ethylene-octene copolymer, reactive compatibilizer, and hyperbranched polyester-modified hydrogenated petroleum resin are added to the main feed port, and pre-dispersant and main antioxidant are added from the side feed port.

[0016] In the aforementioned high-temperature resistant polyolefin hot melt adhesive, the polypropylene copolymer and the metallocene-catalyzed ethylene-octene copolymer synergistically construct a high-temperature resistant matrix, endowing the hot melt adhesive with excellent high-temperature resistance and rigidity. The metallocene-catalyzed ethylene-octene copolymer has a narrow molecular weight distribution and excellent elasticity, providing good low-temperature flexibility and impact resistance. The synergistic effect of the two achieves a balance between high-temperature resistance and low-temperature flexibility. In addition, hyperbranched polyester modified hydrogenated petroleum resin achieves a unity of tackification and compatibility. Hyperbranched polyester has a highly branched three-dimensional dendritic structure and a large number of end functional groups. By melt blending and grafting onto the hydrogenated petroleum resin molecular chain, it significantly improves the compatibility between the tackifying resin and the polyolefin matrix. The introduction of hyperbranched polyester not only enhances the tackification effect but also inhibits the migration of the tackifying resin at high temperatures through its unique spatial configuration, improving the storage stability and high-temperature retention of the hot melt adhesive. At the same time, the terminal hydroxyl groups of the hyperbranched polyester can react with the maleic anhydride groups of the reactive compatibilizer to form a chemical cross-linking network, further improving the heat resistance. Nanonucleating modifiers exhibit excellent interfacial compatibility with the polyolefin matrix, significantly improving the crystallization rate and crystallinity of polypropylene and refining grain size, thereby enhancing the heat resistance and mechanical strength of the hot melt adhesive. Simultaneously, the physical entanglement and interfacial interactions between nanoparticles and polymer segments enhance the material's load-bearing capacity. Reactive compatibilizers also demonstrate good compatibility with the polyolefin matrix, improving the cohesive strength and high-temperature resistance of the hot melt adhesive. A two-stage antioxidant system provides comprehensive thermal and oxygen protection, significantly improving the processing stability and long-term thermal aging performance of the hot melt adhesive. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0018] Example 1: S1: 1 part of nano-nucleating modifier (1 part of nano-silica was surface-treated with 0.2 parts of silane coupling agent and then dried to obtain nano-nucleating modifier) ​​and 8 parts of metallocene-catalyzed ethylene-octene copolymer were pre-mixed in a high-speed mixer for 12 min at a speed of 1000 rpm to obtain a pre-dispersion.

[0019] S2: 25 parts of highly crystalline polypropylene copolymer (random copolymer of propylene and ethylene, ethylene content 2-5 wt%, isotacticity 96%, melt index 8-15 g / 10 min (230℃, 2.16 kg)), 15 parts of metallocene-catalyzed ethylene-octene copolymer (copolymer of ethylene and 1-octene, 1-octene content 15-25 wt%, melt index 3-10 g / 10 min (190℃, 2.16 kg)), and 3 parts of reactive compatibilizer (maleic anhydride-grafted ethylene-octene copolymer). 20 parts of hyperbranched polyester modified hydrogenated petroleum resin (hyperbranched polyester (generation 3-5, molecular weight 2000-5000) and hydrogenated petroleum resin were melt-blended at 190℃, the grafting rate of hyperbranched polyester was 3-8wt%, and the melt index was 5-12g / 10min) were added to the main feed port of a twin-screw extruder, and the nano-nucleating modifier predispersant obtained in step S1 and 1 part of the main antioxidant (pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were added from the side feed port.

[0020] The extruder temperature distribution was controlled as follows: Zone 1 170℃, Zone 2 180℃, Zone 3 190℃, Zone 4 195℃, and Die Head 195℃. The screw speed was 200 rpm, the vacuum degree was -0.07 MPa, and the residence time was 3.5 min to obtain the melt.

[0021] S3: Transfer the melt to an internal mixer, add 6 parts of viscosity modifier (microcrystalline wax) and 0.2 parts of auxiliary antioxidant (tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:2), the mixing temperature is 180℃, the rotor speed is 50 rpm, and the mixing time is 12 min to form a mixture.

[0022] S4: The mixture is transferred to a single-screw extruder, where volatiles are removed at 185°C and a vacuum of -0.09MPa. The mixture is then granulated using an underwater pelletizing system at a cooling water temperature of 20°C and dried to obtain the finished hot melt adhesive granules.

[0023] Example 2 S1: Two parts of nano-nucleating modifier (two parts of nano-silica were surface-treated with 0.5 parts of silane coupling agent and then dried to obtain nano-nucleating modifier) ​​and five parts of metallocene-catalyzed ethylene-octene copolymer were premixed in a high-speed mixer for 12 min at a speed of 1000 rpm to obtain a pre-dispersion.

[0024] S2: 40 parts of highly crystalline polypropylene copolymer (random copolymer of propylene and ethylene, ethylene content 2-5 wt%, isotacticity 96%, melt index 8-15 g / 10 min (230℃, 2.16 kg)), 10 parts of metallocene-catalyzed ethylene-octene copolymer (copolymer of ethylene and 1-octene, 1-octene content 15-25 wt%, melt index 3-10 g / 10 min (190℃, 2.16 kg)), and 8 parts of reactive compatibilizer (maleic anhydride-grafted ethylene-octene copolymer). 35 parts of hyperbranched polyester modified hydrogenated petroleum resin (hyperbranched polyester (generation 3-5, molecular weight 2000-5000) and hydrogenated petroleum resin were melt-blended at 190℃, the grafting rate of hyperbranched polyester was 3-8wt%, and the melt index was 5-12g / 10min) were added to the main feed port of a twin-screw extruder, and the nano-nucleating modifier predispersant obtained in step S1 and 0.5 parts of the main antioxidant (pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were added from the side feed port.

[0025] The extruder temperature distribution was controlled as follows: Zone 1 170℃, Zone 2 180℃, Zone 3 190℃, Zone 4 195℃, and Die Head 195℃. The screw speed was 200 rpm, the vacuum degree was -0.07 MPa, and the residence time was 3.5 min to obtain the melt.

[0026] S3: Transfer the melt to an internal mixer, add 2 parts of viscosity modifier (Fischer-Tropsch wax) and 0.4 parts of auxiliary antioxidant (tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:1), the mixing temperature is 180℃, the rotor speed is 50 rpm, and the mixing time is 12 min to form a mixture.

[0027] S4: The mixture is transferred to a single-screw extruder, where volatiles are removed at 185°C and a vacuum of -0.09MPa. The mixture is then granulated using an underwater pelletizing system at a cooling water temperature of 20°C and dried to obtain the finished hot melt adhesive granules.

[0028] Example 3: S1: 1.5 parts of nano-nucleating modifier (1.5 parts of nano-silica were surface-treated with 0.35 parts of silane coupling agent and then dried to obtain nano-nucleating modifier) ​​and 6 parts of metallocene-catalyzed ethylene-octene copolymer were pre-mixed in a high-speed mixer for 12 min at a speed of 1000 rpm to obtain a pre-dispersion.

[0029] S2: 30 parts of highly crystalline polypropylene copolymer (random copolymer of propylene and ethylene, ethylene content 2-5 wt%, isotacticity 96%, melt index 8-15 g / 10 min (230℃, 2.16 kg)), 12 parts of metallocene-catalyzed ethylene-octene copolymer (copolymer of ethylene and 1-octene, 1-octene content 15-25 wt%, melt index 3-10 g / 10 min (190℃, 2.16 kg)), and 5 parts of reactive compatibilizer (maleic anhydride-grafted ethylene-octene copolymer). 33 parts of hyperbranched polyester modified hydrogenated petroleum resin (hyperbranched polyester (generation 3-5, molecular weight 2000-5000) and hydrogenated petroleum resin were melt-blended at 190℃, the grafting rate of hyperbranched polyester was 3-8wt%, and the melt index was 5-12g / 10min) were added to the main feed port of a twin-screw extruder, and the nano-nucleating modifier predispersant obtained in step S1 and 0.7 parts of the main antioxidant (pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were added from the side feed port.

[0030] The extruder temperature distribution was controlled as follows: Zone 1 170℃, Zone 2 180℃, Zone 3 190℃, Zone 4 195℃, and Die Head 195℃. The screw speed was 200 rpm, the vacuum degree was -0.07 MPa, and the residence time was 3.5 min to obtain the melt.

[0031] S3: Transfer the melt to an internal mixer, add 5 parts of viscosity modifier (Fischer-Tropsch wax and microcrystalline wax in a weight ratio of 1:2) and 0.3 parts of auxiliary antioxidant (tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:1.5), the mixing temperature is 180℃, the rotor speed is 50 rpm, and the mixing time is 12 min to form a mixture.

[0032] S4: The mixture is transferred to a single-screw extruder, where volatiles are removed at 185°C and a vacuum of -0.09MPa. The mixture is then granulated using an underwater pelletizing system at a cooling water temperature of 20°C and dried to obtain the finished hot melt adhesive granules.

[0033] Example 4: S1: 1.5 parts of nano-nucleating modifier (1.5 parts of nano-silica were surface-treated with 0.35 parts of silane coupling agent and then dried to obtain nano-nucleating modifier) ​​and 6 parts of metallocene-catalyzed ethylene-octene copolymer were pre-mixed in a high-speed mixer for 10 min at a speed of 800 rpm to obtain a pre-dispersion.

[0034] S2: 30 parts of highly crystalline polypropylene copolymer (random copolymer of propylene and ethylene, ethylene content 2-5 wt%, isotacticity 96%, melt index 8-15 g / 10 min (230℃, 2.16 kg)), 12 parts of metallocene-catalyzed ethylene-octene copolymer (copolymer of ethylene and 1-octene, 1-octene content 15-25 wt%, melt index 3-10 g / 10 min (190℃, 2.16 kg)), and 5 parts of reactive compatibilizer (maleic anhydride-grafted ethylene-octene copolymer). 33 parts of hyperbranched polyester modified hydrogenated petroleum resin (hyperbranched polyester (generation 3-5, molecular weight 2000-5000) and hydrogenated petroleum resin were melt-blended at 190℃, the grafting rate of hyperbranched polyester was 3-8wt%, and the melt index was 5-12g / 10min) were added to the main feed port of a twin-screw extruder, and the nano-nucleating modifier predispersant obtained in step S1 and 0.7 parts of the main antioxidant (pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) were added from the side feed port.

[0035] The extruder temperature distribution was controlled as follows: Zone 1 165℃, Zone 2 175℃, Zone 3 185℃, Zone 4 190℃, and Die Head 190℃. The screw speed was 150 rpm, the vacuum degree was -0.08 MPa, and the residence time was 4 min to obtain the melt.

[0036] S3: Transfer the melt to an internal mixer, add 5 parts of viscosity modifier (Fischer-Tropsch wax) and 0.3 parts of auxiliary antioxidant (tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:1.5), control the mixing temperature at 185°C, the rotor speed at 40 rpm, and the mixing time at 15 min to form a mixture.

[0037] S4: The mixture is transferred to a single-screw extruder, where volatiles are removed at 180°C and a vacuum of -0.09MPa. The mixture is then granulated using an underwater pelletizing system, cooled at 15°C, and dried to obtain the finished hot melt adhesive granules.

[0038] Example 5: S1: 1.5 parts of nano-nucleating modifier (1.5 parts of nano-silica were surface-treated with 0.35 parts of silane coupling agent and dried to obtain nano-nucleating modifier) ​​and 6 parts of metallocene-catalyzed ethylene-octene copolymer were pre-mixed in a high-speed mixer for 15 min at a speed of 1200 rpm to obtain a pre-dispersion.

[0039] S2: 30 parts of highly crystalline polypropylene copolymer (random copolymer of propylene and ethylene, ethylene content 2-5 wt%, isotacticity 96%, melt index 8-15 g / 10 min (230℃, 2.16 kg)), 12 parts of metallocene-catalyzed ethylene-octene copolymer (copolymer of ethylene and 1-octene, 1-octene content 15-25 wt%, melt index 3-10 g / 10 min (190℃, 2.16 kg)), and 5 parts of reactive compatibilizer (maleic anhydride-grafted ethylene-octene copolymer). 33 parts of hyperbranched polyester modified hydrogenated petroleum resin (hyperbranched polyester (generation 3-5, molecular weight 2000-5000) and hydrogenated petroleum resin were melt-blended at 180-200℃, the grafting rate of hyperbranched polyester was 3-8wt%, and the melt index was 5-12g / 10min) were added to the main feed port of a twin-screw extruder. The nano-nucleating modifier predispersant obtained in step S1 and 0.7 parts of the main antioxidant (pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) were added from the side feed port.

[0040] The extruder temperature distribution was controlled as follows: Zone 1 175℃, Zone 2 185℃, Zone 3 195℃, Zone 4 200℃, and Die head 200℃. The screw speed was 250 rpm, the vacuum degree was -0.06 MPa, and the residence time was 2 min to obtain the melt.

[0041] S3: Transfer the melt to an internal mixer, add 5 parts of viscosity modifier (Fischer-Tropsch wax) and 0.3 parts of auxiliary antioxidant (tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:1.5), control the mixing temperature at 175°C, the rotor speed at 60 rpm, and the mixing time at 10 min to form a mixture.

[0042] S4: The mixture is transferred to a single-screw extruder, where volatiles are removed at 190°C and a vacuum of -0.09MPa. The mixture is then granulated using an underwater pelletizing system, cooled at 25°C, and dried to obtain the finished hot melt adhesive granules.

[0043] Comparative Example 1: A commercially available brand of polyolefin hot melt adhesive.

[0044] Comparative Example 2: S1: Add 25 parts polypropylene, 23 parts metallocene-catalyzed ethylene-octene copolymer (a copolymer of ethylene and 1-octene), 3 parts reactive compatibilizer (maleic anhydride-grafted ethylene-octene copolymer), and 20 parts hydrogenated petroleum resin to the main feed port of the twin-screw extruder. Add 1 part nano silica and 1 part main antioxidant (pentaerythritol tetrakis[-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) from the side feed port.

[0045] The extruder temperature distribution was controlled as follows: Zone 1 170℃, Zone 2 180℃, Zone 3 190℃, Zone 4 195℃, and Die Head 195℃. The screw speed was 200 rpm, the vacuum degree was -0.07 MPa, and the residence time was 3.5 min to obtain the melt.

[0046] S3: Transfer the melt to an internal mixer, add 6 parts of viscosity modifier (microcrystalline wax) and 0.2 parts of auxiliary antioxidant (tris(2,4-di-tert-butylphenyl) phosphite and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate in a weight ratio of 1:2), the mixing temperature is 180℃, the rotor speed is 50 rpm, and the mixing time is 12 min to form a mixture.

[0047] S4: The mixture is transferred to a single-screw extruder, where volatiles are removed at 185°C and a vacuum of -0.09MPa. The mixture is then granulated using an underwater pelletizing system at a cooling water temperature of 20°C and dried to obtain the finished hot melt adhesive granules.

[0048] Performance testing 1. Adhesive Peel Strength: Peel strength tests were conducted on the hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 using a T-peel test according to ASTM D1876-2015. Rectangular steel strips with dimensions of 25mm x 200mm x 0.2mm were used as the test substrate. The hot melt adhesive coating thickness was 0.10mm x 0.005mm. The curing time was 48 hours. Test environmental conditions: temperature 232℃, relative humidity 50.5%.

[0049] Each embodiment or comparative example was tested five times, and the data recorded in the table is the average of the five tests. The test results are shown in Table 1.

[0050] 2. Softening point test The hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 were tested according to GB / T 15332-1994 "Determination of softening point of hot melt adhesives - Ring and Ball Method". The test results are shown in Table 1.

[0051] 3. Melt viscosity test According to GB / T2794-2013 "Determination of viscosity of adhesives", the melt viscosity of the hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 was tested at a test temperature of 180℃. The test results are shown in Table 1.

[0052] 4. High temperature resistance: The hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 were placed in an oven at 150°C and observed for 72 hours to see if the adhesive layer softened, flowed or delaminated. The test results are shown in Table 1.

[0053] 5. Low-temperature flexibility: The hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 were cast into 2mm thick test pieces, placed in a -20℃ low-temperature chamber for 2 hours, and then immediately bent at 180 degrees to observe whether brittle cracking occurred. The test results are shown in Table 1.

[0054] 6. Storage stability: The hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 were placed in an oven at 60°C for 30 days to observe whether oil seepage, clumping or discoloration occurred. The test results are shown in Table 1.

[0055] 7. Thermal Aging Performance: The hot melt adhesives prepared in Examples 1-5 and Comparative Examples 1-2 were heated at 180°C for 4 hours. The change rate of melt viscosity and color change (Gardner colorimetry) before and after heating were measured. The test results are shown in Table 1. Table 1: Test Data Table Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Peel strength (N / 25mm) 9.5 8.8 10.2 9.2 8.9 5.8 5 Softening point (°C) 160 158 162 159 158 148 140 Melt viscosity (180℃, mPas) 8500 8600 8800 8500 8400 6500 10000 High temperature resistance (150℃ for 72 hours) No softening flow No softening flow No softening flow No softening flow No softening flow Slightly flowing at the edges Noticeably softened Low-temperature flexibility (-20℃) No brittleness No brittleness No brittleness No brittleness No brittleness Slight brittleness Moderate brittleness Storage stability (60℃ for 30 days) No change No change No change No change No change Slight oil seepage Slight caking Change rate of viscosity due to thermal aging (%) 8.5 8.8 7.2 8.3 8.1 12.6 13.1 Color change due to thermal aging (Gardner) 1 1 1 1.5 1 3 1 The test data above show that the hot melt adhesives prepared in Examples 1-5 all have a softening point of 158℃, which is significantly higher than that in Comparative Examples 1-2. This indicates that the present invention significantly improves the high temperature resistance of the hot melt adhesive through the synergistic effect of polypropylene copolymer, nano-nucleating modifier and reactive compatibilizer.

[0056] The hot melt adhesives prepared in Examples 1-5 all had a peel strength of 8.8 N / 25 mm, which was much higher than that of Comparative Examples 1-2, indicating that the introduction of hyperbranched polyester modified hydrogenated petroleum resin and reactive compatibilizer significantly enhanced the adhesive properties of the hot melt adhesive.

[0057] Examples 1-5 showed no softening or flowing under 150℃ for 72 hours, while commercially available polyolefin hot melt adhesives showed slight edge flowing. Comparative Example 2 (common nano-silica, common polypropylene, and common hydrogenated petroleum resin) also showed slight edge flowing. This indicates that the selection of the matrix resin, modification of the hydrogenated petroleum resin, and modification of the nano-nucleating agent play a crucial role in the high-temperature resistance of this invention. Examples 1-5 showed no brittleness at -20℃ and exhibited excellent low-temperature flexibility, which is attributed to the toughening effect of the metallocene-catalyzed ethylene-octene copolymer.

[0058] Examples 1-5 showed no changes after 30 days of storage at 60°C, demonstrating excellent storage stability. In contrast, Comparative Examples 1 and 2 showed oil seepage, indicating that the hyperbranched polyester modification effectively inhibited the migration of the tackifying resin.

[0059] The thermal aging viscosity change rate of Examples 1-5 was 8.8%, and the color change was 1.5. The thermal stability was significantly better than that of Comparative Example 1, indicating that the two-stage antioxidant system provided effective thermal and oxygen protection.

[0060] In summary, the polypropylene copolymer and metallocene-catalyzed ethylene-octene copolymer in the high-temperature resistant polyolefin hot melt adhesive prepared in this invention synergistically construct a high-temperature resistant matrix, endowing the hot melt adhesive with excellent high-temperature resistance and rigidity. The metallocene-catalyzed ethylene-octene copolymer has a narrow molecular weight distribution and excellent elasticity, providing good low-temperature flexibility and impact resistance. The synergistic effect of the two achieves a balance between high-temperature resistance and low-temperature flexibility. In addition, hyperbranched polyester modified hydrogenated petroleum resin achieves a unity of tackification and compatibility. Hyperbranched polyester has a highly branched three-dimensional dendritic structure and a large number of end functional groups. By melt blending and grafting onto the molecular chain of hydrogenated petroleum resin, it significantly improves the compatibility between the tackifying resin and the polyolefin matrix. The introduction of hyperbranched polyester not only enhances the tackification effect, but also inhibits the migration of the tackifying resin at high temperatures through its unique spatial configuration, improving the storage stability and high-temperature retention of the hot melt adhesive. At the same time, the terminal hydroxyl groups of hyperbranched polyester can react with the maleic anhydride groups of the reactive compatibilizer to form a chemical cross-linking network, further improving the heat resistance. Nanonucleating modifiers exhibit excellent interfacial compatibility with the polyolefin matrix, significantly improving the crystallization rate and crystallinity of polypropylene and refining grain size, thereby enhancing the heat resistance and mechanical strength of the hot melt adhesive. Simultaneously, the physical entanglement and interfacial interactions between nanoparticles and polymer segments enhance the material's load-bearing capacity. Reactive compatibilizers also demonstrate good compatibility with the polyolefin matrix, improving the cohesive strength and high-temperature resistance of the hot melt adhesive. A two-stage antioxidant system provides comprehensive thermal and oxygen protection, significantly improving the processing stability and long-term thermal aging performance of the hot melt adhesive.

[0061] Therefore, the high-temperature resistant polyolefin hot melt adhesive prepared by this invention has good performance in terms of high temperature resistance, bonding strength, low-temperature flexibility, storage stability and thermal aging performance, and can meet the requirements of current multi-scenario applications.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A high temperature resistant polyolefin hot melt adhesive, characterized in that, By weight parts, including the following components: 25-40 parts of polypropylene copolymer; 5-8 parts of metallocene catalyzed ethylene-octene copolymer; 1-2 parts of nano nucleating modifier; 3-8 parts of reactive compatibilizer; 20-35 parts of hyperbranched polyester modified hydrogenated petroleum resin; 2-6 parts of viscosity modifier; 0.5-1 parts of primary antioxidant; 0.2-0.4 parts of auxiliary antioxidant; The polypropylene copolymer is a copolymer of propylene and ethylene; The hyperbranched polyester modified hydrogenated petroleum resin is prepared by the following method: melt blending hyperbranched polyester with a degree of 3-5 and a molecular weight of 2000-5000 with hydrogenated petroleum resin at 180-200℃ for 20-30 minutes, and cooling to obtain the hyperbranched polyester modified hydrogenated petroleum resin, the hyperbranched polyester grafting rate is 3-8wt%, and the melt index is 5-12g / 10min.

2. The high temperature resistant polyolefin hot melt adhesive according to claim 1, wherein, The nano nucleating modifier is nano silicon dioxide modified by silane coupling agent.

3. The high temperature resistant polyolefin hot melt adhesive according to claim 1, wherein, The reactive compatibilizer is maleic anhydride grafted ethylene-octene copolymer.

4. The high temperature resistant polyolefin hot melt adhesive of claim 1, wherein, The mass ratio of the polypropylene copolymer to the hyperbranched polyester modified hydrogenated petroleum resin is 1:(1-1.2).

5. The high temperature resistant polyolefin hot melt adhesive of claim 1, wherein, In the polypropylene copolymer, the ethylene content is 2-5wt%, the isotacticity is 96%, and the melt index is 8-15g / 10min (230℃, 2.16kg).

6. The high temperature resistant polyolefin hot melt adhesive of claim 1, wherein, The viscosity modifier is Fischer-Tropsch wax and / or microcrystalline wax.

7. The high temperature resistant polyolefin hot melt adhesive of claim 1, wherein, The primary antioxidant is tetra [-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester.

8. The high temperature resistant polyolefin hot melt adhesive of claim 1, wherein, The auxiliary antioxidant is tris (2,4-di-tert-butylphenyl) phosphite and n-hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, the weight ratio of the two is 1:(1-2).

9. A process for the preparation of a high temperature resistant polyolefin hot melt adhesive, for the preparation of the hot melt adhesive according to any one of claims 1 to 8, characterized in that, Including the following steps: Pre-mixing the nano nucleating modifier and the metallocene catalyzed ethylene-octene copolymer in a high-speed mixer to obtain a pre-dispersion; Mixing the polypropylene copolymer, the metallocene catalyzed ethylene-octene copolymer, the reactive compatibilizer, and the hyperbranched polyester modified hydrogenated petroleum resin, adding the pre-dispersion and the primary antioxidant, heating to 165-200℃, and continuously stirring for 2-4min to obtain a melt; Adding the viscosity modifier and the auxiliary antioxidant to the melt, controlling the temperature to be 175-185℃, and stirring for 10-15min to form a mixture; Vacuum devolatilizing the mixture, cooling and granulating, and drying to obtain the hot melt adhesive.

10. The high temperature resistant polyolefin hot melt adhesive according to claim 9, wherein, In the melt preparation step, the melt is carried out by a double screw extruder, wherein the polypropylene copolymer, the metallocene catalyzed ethylene-octene copolymer, the reactive compatibilizer, and the hyperbranched polyester modified hydrogenated petroleum resin are added to the main feeding port, and the pre-dispersion and the primary antioxidant are added from the side feeding port.