Polyolefin adhesive for stainless steel and preparation method thereof

Abstract

The invention relates to a polyolefin adhesive for stainless steel and a preparation method thereof, and belongs to the technical field of adhesives. According to the invention, quinic acid and shikimic acid are firstly used for modifying sodium carbonate, then modified calcium carbonate and ramie fiber are used as fillers for filling so as to construct an efficient stress transfer system, and meanwhile, maleic anhydride grafted polyethylene is also added for assisting filling of the fillers, so that the impact resistance of the prepared adhesive is effectively improved; besides, malonaldehyde is added to reduce the activity of molecules in the material and limit molecular motion, vinyl neodecanoate with a side group is doped to increase the steric hindrance of molecular motion in the system, and hexanediol diglycidyl ether is doped to increase the density of a cross-linked network of the system, so that the composite material has excellent mechanical properties. The adhesive prepared by the method has relatively high peel strength.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a polyolefin adhesive for stainless steel and its preparation method. Background Technology

[0002] Stainless steel, as an important engineering material, is widely used in construction decoration, home appliance manufacturing, electronics, transportation, and chemical equipment due to its excellent mechanical properties, corrosion resistance, and aesthetics. In the processing and use of stainless steel products, it is often necessary to firmly bond them to plastics, composite materials, or other metal components to meet structural, functional, or aesthetic requirements. Polyolefin adhesives have become a popular choice in stainless steel bonding due to their advantages such as good sealing performance, weather resistance, low cost, and simple processing. However, existing polyolefin adhesives, when applied to stainless steel, often fail to meet the stringent requirements of high-end applications in terms of overall performance, particularly impact resistance and peel strength. When the adhesive is subjected to external impact, the adhesive layer cannot effectively absorb and disperse energy through deformation, easily leading to streaks that quickly develop into cracks and brittle fracture. This compromises the safety of the bonded structure under dynamic loads or accidental collisions. Furthermore, adhesives with low peel strength are prone to detaching from the stainless steel substrate under sustained peel stress, severely affecting the reliability and durability of the product.

[0003] Therefore, developing a polyolefin adhesive for stainless steel with high peel strength and high impact resistance will positively promote the application of adhesives in high-end manufacturing industries. Summary of the Invention

[0004] The purpose of this invention is to provide a polyolefin adhesive for stainless steel and its preparation method, which solves the problems of low impact resistance and peel strength in the prior art.

[0005] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention provides a method for preparing a polyolefin adhesive for stainless steel, comprising the following steps: (1) Mix calcium carbonate and deionized water to prepare a slurry, add quinic acid and shikimic acid under controlled temperature, stir, filter, take the filter residue, wash, dry, grind and sieve A to obtain modified calcium carbonate; dry, crush, grind and sieve B of ramie fiber to obtain treated ramie fiber. (2) Mix EVA and xylene and stir under controlled temperature. Add sodium hydroxide-ethanol solution dropwise and stir again. Cool, add anhydrous ethanol, filter, take the filter residue, wash, and dry under controlled temperature to obtain intermediate material A. (3) Introduce nitrogen gas, mix p-toluenesulfonic acid and EVA, and then knead A under controlled temperature. Cool to room temperature to obtain kneaded material A; bubble malondialdehyde aqueous solution with nitrogen gas, mix it with intermediate material A and kneaded material A, and then knead B under controlled temperature to obtain intermediate material B. (4) The intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, neodecanoate vinyl ester, hexanediol diglycidyl ether, tackifying resin, wax and antioxidant are placed in a twin-screw extruder and extruded, cooled, discharged and pelletized to obtain polyolefin adhesive.

[0006] As a preferred technical solution of the present invention, the quinic acid in step (1) is dextrorotatory quinic acid.

[0007] As a preferred technical solution of the present invention, the mass fraction of the slurry in step (1) is 15-20 wt%; the amount of quinic acid added is 5-8% of the mass of the slurry, and the amount of shikimic acid added is 3-5% of the mass of the slurry.

[0008] As a preferred technical solution of the present invention, the calcium carbonate in step (1) is 2800 mesh; the temperature for temperature control is 65-70℃; the stirring time is 0.5-1h; the washing is washing with deionized water 2-3 times; the drying is drying to a moisture content ≤2%; the sieving is passing through a 1000 mesh sieve; and the sieving B is passing through a 140 mesh sieve.

[0009] As a preferred technical solution of the present invention, the ratio of EVA, xylene, sodium hydroxide-ethanol solution and anhydrous ethanol in step (2) is 22-24.5g:235-250mL:95-102mL:350-368mL.

[0010] As a preferred technical solution of the present invention, the concentration of sodium hydroxide-ethanol solution in step (2) is 0.5 mol / L.

[0011] As a preferred technical solution of the present invention, the temperature-controlled stirring in step (2) is magnetic stirring at 85-90℃ for 20-30 minutes; the re-stirring time is 1.5-2 hours; the cooling is cooling to room temperature; the filter residue washing is washing the filter residue once with hydrochloric acid solution, 5-7 times with deionized water, and 4-5 times with anhydrous ethanol; and the temperature-controlled drying is vacuum drying at 45-50℃ to constant weight.

[0012] Furthermore, the concentration of the hydrochloric acid solution is 1 mol / L.

[0013] As a preferred technical solution of the present invention, the mass ratio of toluenesulfonic acid and EVA in step (3) is 1-1.2:8-9; the mass ratio of malondialdehyde aqueous solution, intermediate material A and mortar A is 4-4.8:88-95:7.5-9.

[0014] As a preferred technical solution of the present invention, the mass concentration of the malondialdehyde aqueous solution in step (3) is 30-35%.

[0015] As a preferred technical solution of the present invention, the temperature of the temperature-controlled mixing A in step (3) is 105-110℃ and the time is 5-8min; the time of nitrogen bubbling is 10-12min; the temperature of the temperature-controlled mixing B is 85-95℃ and the time is 2-3min.

[0016] As a preferred technical solution of the present invention, the mass ratio of intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, neodecanoate, hexanediol diglycidyl ether, tackifying resin, wax and antioxidant in step (4) is 21-24:30-38:3-5.5:4-6:2-3:6-8:1.4-2:30-45:5-10:0.5-1.

[0017] Furthermore, the tackifying resin includes at least one of α-terpene resin, β-terpene resin, maleic rosin ester, C5 petroleum resin, C5C9 copolymer petroleum resin, C5 hydrogenated petroleum resin, and C9 hydrogenated petroleum resin.

[0018] Furthermore, the wax includes at least one of paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and polyethylene wax.

[0019] Furthermore, the antioxidant includes antioxidant 1010 or antioxidant 1076.

[0020] As a preferred technical solution of the present invention, the temperatures of the inlet section, the middle section and the outlet section of the twin-screw extruder in step (4) are 100-110℃, 160-170℃ and 110-120℃, respectively.

[0021] The second aspect of the present invention provides a polyolefin adhesive prepared by the above-mentioned method for preparing polyolefin adhesive for stainless steel.

[0022] The beneficial effects of this invention are: (1) In this invention, calcium carbonate and ramie fiber, which have good mechanical properties, are selected as fillers. Quinic acid and shikimic acid are used to form coordination bonds with calcium ions on the surface of calcium carbonate through carboxyl groups, thereby improving the surface activity of calcium carbonate, effectively inhibiting the aggregation of calcium carbonate and further enhancing the interfacial bonding strength between calcium carbonate and the matrix. At the same time, the free hydroxyl groups in quinic acid and shikimic acid molecules will form a hydrogen bond network with the surface groups of ramie fiber, thereby enhancing the multiphase interfacial bonding between calcium carbonate-ramie fiber-matrix. In addition, the hydrogen bonds and coordination bonds formed in the system also have a synergistic effect, which can effectively construct an efficient stress transfer system, thus significantly improving the impact resistance of the adhesive.

[0023] (2) In this invention, maleic anhydride-grafted polyethylene is used to assist in filling the filler. The maleic anhydride groups are introduced to interact with the filler surface, making the filler more uniform and delicate in dispersion. In addition, the molecular chains formed by maleic anhydride-grafted polyethylene due to its good compatibility with the matrix are intertwined and diffused with each other, which can improve the adhesion between the filler and the matrix and thus effectively improve the impact resistance of the adhesive.

[0024] (3) In this invention, malondialdehyde is added to the system to form an acetal, which reduces the activity of molecules inside the material and restricts molecular movement. At the same time, neodecanoic acid vinyl ester with side groups is added to increase the steric hindrance of molecular movement inside the system, and hexanediol diglycidyl ether is added to increase the crosslinking network density of the system. Therefore, the adhesive obtained in this way has high peel strength. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the finished product of the polyolefin adhesive for stainless steel according to the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In the following embodiments and comparative examples: Calcium carbonate, type C-2800, purchased from Hezhou Yitai Chemical Co., Ltd. Ramie fiber, model: TEADIT 2153, purchased from: Nanjing Ruipingde Electromechanical Equipment Co., Ltd.; Dextrorotatory quinic acid, purchased from: Hubei Xinhongli Chemical Co., Ltd.; Shikimic acid, purchased from: Xi'an Jinheng Chemical Co., Ltd.; EVA (ethylene-vinyl acetate copolymer), product number: HH60113IBHLC, purchased from: Dongguan Shenghao Plastic Raw Materials Co., Ltd. Linear low-density polyethylene, grade: 9730, purchased from: Dongguan Mingyuan Plastics Co., Ltd. Maleic anhydride-grafted polyethylene, model: TG915, manufactured in-house; The above will not be repeated hereafter.

[0029] The technical solution of the present invention will be further described below with reference to the embodiments.

[0030] Example 1 A method for preparing a polyolefin adhesive for stainless steel includes the following steps: (1) Mix calcium carbonate and deionized water to prepare a slurry with a mass fraction of 15wt%. Add dextrorotatory quinic acid and shikimic acid at a temperature of 67.5℃, stir for 0.5h, filter, take the filter residue, wash it with deionized water 3 times, dry it to a moisture content of ≤2%, grind it, and pass it through a 1000-mesh sieve to obtain modified calcium carbonate; dry ramie fiber to a moisture content of ≤2%, crush it, grind it, and pass it through a 140-mesh sieve to obtain treated ramie fiber; The calcium carbonate is 2800 mesh; the amount of dextrorotatory quinic acid added is 5% of the slurry mass; the amount of shikimic acid added is 4% of the slurry mass. (2) Mix EVA and xylene and stir magnetically at 90℃ for 20 min. Add 0.5 mol / L sodium hydroxide-ethanol solution dropwise and stir for 2 h. Cool to room temperature, add anhydrous ethanol, filter, and take the filter residue to wash once with 1 mol / L hydrochloric acid solution, five times with deionized water, and five times with anhydrous ethanol. Dry under vacuum at 50℃ to constant weight to obtain intermediate material A. The ratio of EVA, xylene, sodium hydroxide-ethanol solution and anhydrous ethanol is 22-24.5g:235-250mL:95-102mL:350-368mL; (3) Introduce nitrogen gas, mix p-toluenesulfonic acid and EVA at a mass ratio of 1.2:8.5, and knead at 105°C for 5 minutes. Cool to room temperature to obtain kneaded material A. Bubble a 30% malondialdehyde aqueous solution with nitrogen gas for 10 minutes, mix it with intermediate material A and kneaded material A, and knead at 90°C for 3 minutes to obtain intermediate material B. The mass ratio of the malondialdehyde aqueous solution, intermediate material A, and internal mixer A is 4.4:91.5:8.2; (4) The intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, neodecanoate vinyl ester, hexanediol diglycidyl ether, tackifying resin, wax and antioxidant are placed in a twin-screw extruder and extruded, cooled, discharged and pelletized to obtain polyolefin adhesive. The mass ratio of intermediate material B, linear low-density polyethylene, maleic anhydride-grafted polyethylene, modified calcium carbonate, treated ramie fiber, vinylidene neodecanoate, hexanediol diglycidyl ether, tackifying resin, wax, and antioxidant is 24:34:5.5:5:2.5:6:1.4:37.5:7.5:0.5. The tackifying resin is C5 petroleum resin; the wax is paraffin wax; the antioxidant is antioxidant 1076. The temperatures of the inlet section, middle section, and outlet section of the twin-screw extruder are 105℃, 160℃, and 110℃, respectively.

[0031] Example 2 A method for preparing a polyolefin adhesive for stainless steel includes the following steps: (1) Mix calcium carbonate and deionized water to prepare a slurry with a mass fraction of 20wt%, add dextrorotatory quinic acid and shikimic acid at a temperature of 65℃, stir for 1h, filter, take the filter residue, wash it twice with deionized water, dry it to a moisture content of ≤2%, grind it, and pass it through a 1000-mesh sieve to obtain modified calcium carbonate; dry ramie fiber to a moisture content of ≤2%, crush it, grind it, and pass it through a 140-mesh sieve to obtain treated ramie fiber; The calcium carbonate is 2800 mesh; the amount of dextrorotatory quinic acid added is 6.5% of the slurry mass; the amount of shikimic acid added is 3% of the slurry mass. (2) Mix EVA and xylene and stir magnetically at 85℃ for 25 min. Add 0.5 mol / L sodium hydroxide-ethanol solution dropwise and stir for 1.5 h. Cool to room temperature, add anhydrous ethanol, filter, and take the filter residue to wash once with 1 mol / L hydrochloric acid solution, six times with deionized water, and four times with anhydrous ethanol. Dry under vacuum at 45℃ to constant weight to obtain intermediate material A. The ratio of EVA, xylene, sodium hydroxide-ethanol solution and anhydrous ethanol is 22-24.5g:235-250mL:95-102mL:350-368mL; (3) Introduce nitrogen gas, mix p-toluenesulfonic acid and EVA at a mass ratio of 1.1:9, and knead at 110°C for 6.5 min. Cool to room temperature to obtain kneaded material A. Bubble a 33% malondialdehyde aqueous solution with nitrogen gas for 11 min, mix it with intermediate material A and kneaded material A, and knead at 85°C for 2 min to obtain intermediate material B. The mass ratio of the malondialdehyde aqueous solution, intermediate material A, and mortar A is 4:88:7.5; (4) The intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, neodecanoate vinyl ester, hexanediol diglycidyl ether, tackifying resin, wax and antioxidant are placed in a twin-screw extruder and extruded, cooled, discharged and pelletized to obtain polyolefin adhesive. The mass ratio of intermediate material B, linear low-density polyethylene, maleic anhydride-grafted polyethylene, modified calcium carbonate, treated ramie fiber, vinyl decanoate, hexanediol diglycidyl ether, tackifying resin, wax, and antioxidant is 21:30:3:4:2:8:1.7:30:10:0.75. The tackifying resin is C9 hydrogenated petroleum resin; the wax is Fischer-Tropsch wax; the antioxidant is antioxidant 1010. The temperatures of the inlet section, middle section, and outlet section of the twin-screw extruder are 100℃, 165℃, and 120℃, respectively.

[0032] Example 3 A method for preparing a polyolefin adhesive for stainless steel includes the following steps: (1) Mix calcium carbonate and deionized water to prepare a slurry with a mass fraction of 18wt%, add dextrorotatory quinic acid and shikimic acid at a temperature of 70℃, stir for 1 hour, filter, take the filter residue, wash it with deionized water 3 times, dry it to a moisture content of ≤2%, grind it, and pass it through a 1000-mesh sieve to obtain modified calcium carbonate; dry ramie fiber to a moisture content of ≤2%, crush it, grind it, and pass it through a 140-mesh sieve to obtain treated ramie fiber; The calcium carbonate is 2800 mesh; the amount of dextrorotatory quinic acid added is 8% of the slurry mass; the amount of shikimic acid added is 5% of the slurry mass. (2) Mix EVA and xylene and stir magnetically at 87.5℃ for 30 min. Add 0.5 mol / L sodium hydroxide-ethanol solution dropwise and stir for 2 h. Cool to room temperature, add anhydrous ethanol, filter, and take the filter residue to wash once with 1 mol / L hydrochloric acid solution, seven times with deionized water, and five times with anhydrous ethanol. Dry under vacuum at 47.5℃ to constant weight to obtain intermediate material A. The ratio of EVA, xylene, sodium hydroxide-ethanol solution and anhydrous ethanol is 22-24.5g:235-250mL:95-102mL:350-368mL; (3) Introduce nitrogen gas, mix p-toluenesulfonic acid and EVA at a mass ratio of 1:8, and knead at 107.5℃ for 8 minutes. Cool to room temperature to obtain kneaded material A. Bubble a 35% malondialdehyde aqueous solution with nitrogen gas for 12 minutes, mix it with intermediate material A and kneaded material A, and knead at 95℃ for 3 minutes to obtain intermediate material B. The mass ratio of the malondialdehyde aqueous solution, intermediate material A, and internal mixing material A is 4.8:95:9; (4) The intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, neodecanoate vinyl ester, hexanediol diglycidyl ether, tackifying resin, wax and antioxidant are placed in a twin-screw extruder and extruded, cooled, discharged and pelletized to obtain polyolefin adhesive. The mass ratio of intermediate material B, linear low-density polyethylene, maleic anhydride-grafted polyethylene, modified calcium carbonate, treated ramie fiber, vinyl decanoate, hexanediol diglycidyl ether, tackifying resin, wax, and antioxidant is 22.5:38:4.2:6:3:7:2:45:5:1. The tackifying resin is C5 hydrogenated petroleum resin; the wax is polyethylene wax; the antioxidant is antioxidant 1076. The temperatures of the inlet section, middle section, and outlet section of the twin-screw extruder are 110℃, 170℃, and 115℃, respectively.

[0033] Comparative Example 1 Compared with Example 1, the difference is that dextroquinic acid is not added in step (1), while the rest remains the same.

[0034] Comparative Example 2 Compared with Example 1, the difference is that shikimic acid is not added in step (1), while the rest remains the same.

[0035] Comparative Example 3 Compared with Example 1, the difference is that modified calcium carbonate is not added in step (4), while the rest remains the same.

[0036] Comparative Example 4 Compared with Example 1, the difference is that no treated ramie fiber is added in step (4), while the rest remains the same.

[0037] Comparative Example 5 Compared with Example 1, the difference is that maleic anhydride-grafted polyethylene is not added in step (4), while the rest remains the same.

[0038] Comparative Example 6 Compared with Example 1, the difference is that malondialdehyde is not added in step (3), while the rest remains the same.

[0039] Comparative Example 7 Compared with Example 1, the difference is that vinyl decanoate is not added in step (4), while the rest remains the same.

[0040] Comparative Example 8 Compared with Example 1, the difference is that hexanediol diglycidyl ether is not added in step (4), while the rest remains the same.

[0041] Test case (1) Activation test: The activation of modified calcium carbonate prepared in step (1) of Examples 1-3 and Comparative Examples 1-2 was tested according to GB / T 19281-2014 to reflect the dispersibility of modified calcium carbonate. The results are shown in Table 1. (2) Impact resistance test: The shear impact strength of the polyolefin adhesives prepared in Examples 1-3 and Comparative Examples 1-5 were tested according to GB / T 6328-2021, and the results are shown in Table 1. (3) Peel strength test: According to GB / T 2791-1995, the peel strength of the polyolefin adhesives prepared in Examples 1-3 and Comparative Examples 6-8 were tested respectively. The tensile rate was set to 100 mm / min. The results are shown in Table 1.

[0042] Table 1 As can be seen from the activation data in Table 1, the present invention uses quinic acid and shikimic acid to modify calcium carbonate, which can effectively inhibit the aggregation of calcium carbonate and further enhance the interfacial bonding strength between calcium carbonate and the matrix. The shear impact strength data clearly shows that the efficient stress transfer system constructed in this invention and the added maleic anhydride-grafted polyethylene have a positive effect on improving the impact resistance of the adhesive. It is easy to see from the 180° peel strength data that the adhesive prepared in this application has high peel strength.

[0043] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0044] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a polyolefin adhesive for stainless steel, characterized by, It comprises the following steps: (1) mixing calcium carbonate and deionized water to configure a slurry, adding quinic acid and shikimic acid under temperature control, stirring, filtering, taking the filter residue, washing, drying, grinding, and sieving A, to obtain modified calcium carbonate; drying, crushing, grinding, and sieving B of ramie fiber, to obtain treated ramie fiber; (2) mixing EVA and xylene under temperature control and stirring, adding sodium hydroxide-ethanol solution drop by drop and stirring again, cooling, adding anhydrous ethanol, filtering, taking the filter residue, washing, and drying under temperature control, to obtain intermediate material A; (3) introducing nitrogen, mixing p-toluenesulfonic acid and EVA under temperature control and internal mixing A, cooling to room temperature, to obtain internal mixing material A; bubbling the malondialdehyde aqueous solution with nitrogen, mixing with intermediate material A and internal mixing material A under temperature control and internal mixing B, to obtain intermediate material B; (4) placing intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, vinyl neodecanoate, hexanediol diglycidyl ether, tackifying resin, wax, and antioxidant in a double-screw extruder for extrusion, cooling, discharging, and pelletizing, to obtain polyolefin bonding adhesive.

2. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, In step (1), the quinic acid is d-quinic acid; the mass fraction of the slurry is 15-20 wt%; the addition amount of the quinic acid is 5-8% of the mass of the slurry, and the addition amount of the shikimic acid is 3-5% of the mass of the slurry.

3. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, In step (2), the amount ratio of EVA, xylene, sodium hydroxide-ethanol solution, and anhydrous ethanol is 22-24.5 g:235-250 mL:95-102 mL:350-368 mL.

4. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, In step (2), the temperature-controlled stirring is magnetic stirring at 85-90℃ for 20-30 min; the stirring time is 1.5-2 h; the cooling is cooling to room temperature; the filter residue is washed with hydrochloric acid solution once, deionized water 5-7 times, and anhydrous ethanol 4-5 times; and the temperature-controlled drying is vacuum drying at 45-50℃ until constant weight.

5. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, In step (3), the mass ratio of p-toluenesulfonic acid to EVA is 1-1.2:8-9; and the mass ratio of the malondialdehyde aqueous solution, intermediate material A, and internal mixing material A is 4-4.8:88-95:7.5-9.

6. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, In step (3), the temperature of the temperature-controlled internal mixing A is 105-110℃, and the time is 5-8 min; the nitrogen bubbling time is 10-12 min; and the temperature of the temperature-controlled internal mixing B is 85-95℃, and the time is 2-3 min.

7. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, In step (4), the mass ratio of intermediate material B, linear low-density polyethylene, maleic anhydride grafted polyethylene, modified calcium carbonate, treated ramie fiber, vinyl neodecanoate, hexanediol diglycidyl ether, tackifying resin, wax, and antioxidant is 21-24:30-38:3-5.5:4-6:2-3:6-8:1.4-2:30-45:5-10:0.5-1.

8. The method for preparing the polyolefin adhesive for stainless steel according to claim 7, characterized in that, The tackifying resin comprises at least one of α-terpene resin, β-terpene resin, maleated rosin, C5 petroleum resin, C5C9 copolymer petroleum resin, C5 hydrogenated petroleum resin, C9 hydrogenated petroleum resin; the wax comprises at least one of paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax; the antioxidant comprises antioxidant 1010 or antioxidant 1076.

9. The method for preparing the polyolefin adhesive for stainless steel according to claim 1, characterized in that, The temperatures of the inlet section, the middle section and the outlet section of the twin-screw extruder in step (4) are 100-110 DEG C, 160-170 DEG C, 110-120 DEG C respectively.

10. A polyolefin adhesive for stainless steel prepared by the method of any one of claims 1-9.

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