Irradiation cross-linked polypropylene superfine pore foam material as well as preparation method and application thereof

Abstract

The invention discloses an irradiation crosslinking polypropylene superfine pore foam material as well as a preparation method and application thereof. According to the preparation method, ethylene silane modified azodicarbonamide and liquid polyisoprene are taken as assistant crosslinking agents, zinc toluenesulfinate is taken as a foaming catalyst, montmorillonite intercalated azodicarbonamide is taken as a foaming agent, homo-polypropylene, low-density polyethylene and an elastomer are compounded, and the irradiation crosslinking high-foaming polypropylene material with a superfine uniform cellular structure is obtained. The product obtained by the preparation method disclosed by the invention is uniform in foam structure, and the pore diameter is within 0.05 mm; the heat resistance is good and can reach 120 DEG C or above; the strength is high, the foaming ratio is large, and when the apparent density is smaller than 0.067 g / cm < 3 > and the thickness is 1 mm, the tensile strength is 1.3 MPa or above, and the elongation is 250% or above; the permanent compression deformation rate is within 25%; and the material is widely applied to the field of power battery gaskets.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to an irradiated cross-linked polypropylene ultrafine pore foam material, a preparation method thereof and an application thereof. Background Art

[0002] Radiation cross-linked polyethylene foam plastic is a foamed plastic with a closed-cell structure between soft (polyurethane) and hard (polystyrene) foam plastics, and has a series of characteristics such as superior toughness, elasticity, flexibility, wear resistance, chemical corrosion resistance, low temperature resistance and good insulation. It can be used as good insulation, heat insulation, shock-proof and buoyancy materials, and is widely used in various fields such as industry, agriculture, construction and transportation. However, the application of PE foam plastic is limited due to its poor mechanical properties, poor heat resistance (the maximum use temperature is only about 80 °C) and difficulty in degradation. Polypropylene (PP) foam has many excellent properties, including low price, good heat resistance, high melting point, high tensile modulus, low density and good chemical resistance, becoming the "new favorite" in the foaming industry. In terms of mechanical properties, PP has a higher static load-bearing capacity than PE and higher impact toughness than PS. Polypropylene (PP) foaming materials have received extensive attention due to their excellent heat resistance, mechanical properties and environmental friendliness, and have become high-performance green foaming materials replacing PU, PE and PS foam materials in developed countries such as Europe, the United States and Japan.

[0003] Despite its excellent performance, PP foaming still faces many difficulties. The main reason is that the molecular chain of ordinary PP is a linear structure. During the foaming process, the biaxial stretching effect experienced by the cell wall will quickly open the entanglement of the linear chain, and the molecular chain is prone to relative sliding, so the tensile viscosity is relatively low. Even a small stress will cause a large deformation of PP, so the strength of the cell wall is not high during the foaming process and is prone to rupture. At the same time, a large amount of gas in the bubbles escapes and diffuses into the environment, ultimately resulting in defects such as thick cell wall, uneven cell size and low foaming ratio of the foamed product. At the same time, due to the high melting point of homopolymer PP, the extrusion processing temperature is above 150 °C. During this high-temperature processing process, the traditional Ac foaming system of polyethylene cannot be used. In the field of power battery gaskets, strict requirements are imposed on the pore structure of the foaming material. Generally, only microcellular foamed polypropylene meets the requirements. However, the preparation conditions of supercritical carbon dioxide microcellular foaming materials are harsh and require high-pressure conditions. There are obvious differences in the foaming degree between the surface and the center of the obtained materials, and it is difficult to meet the requirements of continuous production. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides an irradiated cross-linked polypropylene ultrafine pore foam material, its preparation method and application. The present invention uses ethylene silane modified azodicarbonamide and liquid polyisoprene as co-crosslinking agents to promote the cross-linking of polypropylene, avoid the degradation of tertiary carbon, utilize the high affinity of polyisoprene with PP to promote its uniform distribution in PP, utilize the high melting point of polyisoprene to solve the problem of migration and precipitation of traditional small molecule co-crosslinking agents, and utilize the participation of alkenyl silane in cross-linking to form uniform and fine foaming nuclei to promote uniform foaming. Zinc benzenesulfinate is used as a foaming catalyst to effectively increase the decomposition temperature of azodicarbonamide and promote the uniformity of the cell structure. Montmorillonite intercalated azodicarbonamide is used as a foaming agent to effectively increase the foaming pressure and reduce gas escape, forming a uniform ultrafine cell structure to replace expensive MPP foaming materials.

[0005] To achieve the above invention purpose, the present invention is realized by the following technical solutions:

[0006] The present invention provides an irradiated cross-linked polypropylene ultrafine pore foam material, and by weight, its raw materials include:

[0007]

[0008] Furthermore, the foam material has good heat resistance, up to above 120 °C; the material has high strength, large foaming ratio, and the apparent density is less than 0.067 g / cm 3 When it is, with a thickness of 1 mm, the tensile strength is above 0.8 MPa, and the elongation at break is above 250%; the permanent compression set rate of the material is within 25%.

[0009] Furthermore, the preparation steps of the ethylene silane modified azodicarbonamide are as follows: Azodicarbonamide with a particle size of 15 - 30 um is dispersed in toluene at a mass ratio of 1:10, then vinyltriethoxysilane with a mass ratio of 3 - 15:10 to azodicarbonamide is added, and reflux reaction is carried out for 4 - 24 h, then filtration and separation are carried out, and vacuum drying is carried out to obtain ethylene silane modified azodicarbonamide.

[0010] Preferably, the preparation steps of the ethylene silane modified azodicarbonamide are as follows: 10 parts by mass of azodicarbonamide with a particle size of 15 - 30 um is dispersed in 100 parts by mass of toluene, 10 parts by mass of vinyltriethoxysilane is added, and reflux reaction is carried out for 12 h, then filtration and separation are carried out, then pressure filtration is carried out with a 1000-mesh filter bag, washed twice with toluene, and vacuum dried at 80 °C to obtain ethylene silane modified azodicarbonamide.

[0011] Further, the preparation steps of the montmorillonite intercalated azodicarbonamide are as follows: fully disperse sodium montmorillonite in deionized water with a mass ratio of 1:100, and stir for 2 h to form a slurry; disperse azodicarbonamide with a particle size of 15-30 μm and a mass ratio of 1-3:2 to sodium montmorillonite in dimethyl sulfoxide with a mass ratio of 10:1 to it, and then add it to the slurry. After vigorously stirring at a high temperature for 24 h, centrifuge and vacuum dry to obtain montmorillonite intercalated azodicarbonamide.

[0012] Preferably, the preparation steps of the montmorillonite intercalated azodicarbonamide are as follows: fully disperse 10 parts by mass of sodium montmorillonite in 1000 parts by mass of deionized water, and stir for 2 h to form a slurry; disperse 10 parts by mass of azodicarbonamide with a particle size of 15-30 μm in 100 parts by mass of dimethyl sulfoxide, and add it to the montmorillonite slurry; after vigorously stirring at 80 °C for 24 h, centrifuge (centrifugation speed 2000 rpm, time 5 min) and separate, and then vacuum dry at 80 °C to obtain montmorillonite intercalated azodicarbonamide.

[0013] Further, the elastomer is at least one of ethylene-propylene-diene monomer rubber, ethylene-octene copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, natural rubber, isobutyl rubber, styrene-butadiene rubber, styrene-butadiene block copolymer, and pentaphenyl block copolymer.

[0014] Further, the polypropylene is homopolypropylene, with a melt index of 0.5-5 g / 10 min and a melting point of 145-167 °C; the molecular weight of the liquid polyisoprene is 20000-70000, and the viscosity is 50-280 Pa·s; the low-density polyethylene is general low-density polyethylene with a density of 0.901-0.922 g / cm 3 , melt index of 1-6 g / 10 min, or linear low-density polyethylene with a density of 0.905-0.930 g / cm 3 , melt index of 0.3-5 g / 10 min.

[0015] Preferably, the molecular weight of the liquid polyisoprene is 30000-50000, and the viscosity is 70-100 Pa·s.

[0016] Further, the flame retardant is a composite of decabromodiphenylethane and antimony trioxide, and the mass ratio of the two is 3:1; the antioxidant is at least one of pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene, butylated hydroxyanisole, dibutylhydroxytoluene, propyl gallate, tert-butylhydroquinone.

[0017] The present invention also provides a method for preparing the irradiated cross-linked polypropylene ultrafine pore foam material, which comprises the following steps:

[0018] (1) Mix polypropylene, elastomer, low-density polyethylene, liquid polyisoprene, vinyl silane-modified azodicarbonamide, montmorillonite intercalated azodicarbonamide, zinc benzenesulfinate, flame retardant, and antioxidant, and then add them to a screw extruder for kneading and extrusion to obtain a masterbatch;

[0019] (2) Electronically irradiate and cross-link the masterbatch, and then subject the obtained material to high-temperature foaming treatment to obtain the irradiated cross-linked polypropylene ultrafine pore foam material.

[0020] Further, in the step (1), the extrusion temperature of the screw extruder is 120-170°C, the screw speed is 5-50 rpm, and the die head temperature is 160-180°C.

[0021] Further, in the step (2), an electron accelerator is used for irradiation cross-linking, and the irradiation dose of the irradiation cross-linking is 4-40 kGy; the high-temperature foaming treatment is carried out in a foaming furnace, the temperature of the foaming furnace is 180-280°C, and the foaming time is 0.1-3 min.

[0022] The present invention also provides the application of the irradiated cross-linked polypropylene ultrafine pore foam material in the preparation of power battery gaskets.

[0023] Further, the thickness of the foam material is 0.1-10 mm, and the thickness deviation is within 10%; at least 2 layers of pores are included in the thickness direction; the pore diameter is within 0.05 mm and is evenly distributed.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The product has a uniform pore structure, and the pore diameter is within 0.05 mm;

[0026] (2) The product has good heat resistance and can reach above 120°C;

[0027] (3) The product has high strength, large foaming ratio, and apparent density less than 0.067 g / cm 3 When the thickness is 1 mm, the tensile strength is above 0.8 MPa and the elongation at break is above 250%;

[0028] (4) The permanent compression set rate of the product is within 25%;

[0029] (5) The obtained material has wide applications in the field of power battery gaskets.

[0030] The present invention uses ethylene silane modified azodicarbonamide and liquid polyisoprene as co-crosslinking agents, zinc benzenesulfonate as a foaming catalyst, montmorillonite intercalated azodicarbonamide as a foaming agent, and a blend of homopolypropylene, low-density polyethylene and elastomer, and obtains an irradiated cross-linked high-foaming polypropylene material with an ultra-fine and uniform cell structure, which is the most suitable method at present. Detailed Embodiments

[0031] The present invention introduces ethylene silane modified azodicarbonamide and liquid polyisoprene as co-crosslinking agents, zinc benzenesulfonate as a foaming catalyst, montmorillonite intercalated azodicarbonamide as a foaming agent into the polyethylene foam material formula, blends polypropylene with linear low-density polyethylene, and forms a three-dimensional cross-linked network through irradiation cross-linking and high-temperature foaming to prepare an irradiated cross-linked high-foaming polypropylene material with an ultra-fine and uniform cell structure.

[0032] The following will describe the preferred embodiments of the present invention in detail to more clearly understand the purpose, features and advantages of the present invention.

[0033] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0034] It should be noted that:

[0035] (1) The present invention uses GB / T 6344-1996 Test Method for Tensile Strength and Elongation at Break of Flexible Cellular Polymer Materials to test the tensile strength and elongation at break;

[0036] (2) The present invention uses GBT6669-2001 Test Method for Compression Set of Flexible Cellular Polymer Materials to test the permanent deformation rate of the sample after being compressed to 50% and placed at 100 °C for 24 h and then restored at room temperature for 24 h;

[0037] (3) The present invention uses GB / T 3682-2000 Determination of Melt Mass-Flow Rate and Melt Volume-Flow Rate of Thermoplastics to test the melt index;

[0038] (4) The present invention uses GB / T1033-1986 Test Method for Density and Relative Density of Plastics to test the material density;

[0039] (5) The surface hardness of the material is measured by using a durometer to measure the indentation hardness (Shore hardness) according to GB / T 2411-2008 for plastics and hard rubbers.

[0040] (6) The water absorption rate of the material is measured according to ASTM D1056.

[0041] Example 1

[0042] A preparation method of an irradiated cross-linked polypropylene ultra-fine pore foam (MIXPP) material, comprising the following steps:

[0043] Step 1: Ethylene silane modified azodicarbonamide

[0044] 10 parts by mass of azodicarbonamide with a particle size of 15 - 30 μm is dispersed in 100 parts by mass of toluene, 10 parts by mass of vinyltriethoxysilane is added, and reflux reaction is carried out for 12 h. Then, it is pressure-filtered with a 1000-mesh filter bag, washed twice with toluene, and vacuum-dried at 80 °C to obtain ethylene silane modified azodicarbonamide.

[0045] Step 2: Montmorillonite intercalated azodicarbonamide

[0046] 10 parts by mass of sodium montmorillonite is fully dispersed in 1000 parts by mass of deionized water, and stirred for 2 h to form a slurry. 10 parts by mass of azodicarbonamide with a particle size of 15 - 30 μm is dispersed in 100 parts by mass of dimethyl sulfoxide, and then added to the previous montmorillonite slurry. After vigorously stirring at 80 °C for 24 h, centrifugal separation is carried out at a centrifugal speed of 2000 rpm for 5 min, and vacuum-dried at 80 °C to obtain montmorillonite intercalated azodicarbonamide.

[0047] Step 3: Preparation of polypropylene foam

[0048] 40 parts by weight of homopolypropylene (PP PPC 5660, Total of France, 0.905 g / cm 3 , MI 7 g / 10 min), 5 parts by weight of elastomer (POE Engage 8842, Dow, 0.857 g / cm 3 , MI (230 °C / 2.16 kg) 1.0 g / 10 min), 15 parts by weight of low density polyethylene (LLDPE 4157, DowDuPont, 0.92 g / cm 3, MI (230 °C / 2.16 kg) 3.0 g / 10 min), 5 parts by weight of liquid polyisoprene (molecular weight of about 30,000, viscosity 120 Pa·s), 10 parts by weight of ethylene silane-modified azodicarbonamide, 20 parts by weight of montmorillonite intercalated azodicarbonamide, 1.5 parts by weight of zinc benzenesulfinate, 10 parts by weight of flame retardant (a composite of decabromodiphenylethane and antimony trioxide mixed in a mass ratio of 3:1), 2 parts by weight of antioxidant 1010, added to a screw extruder for plasticizing and extruding a masterbatch sheet, controlling the extrusion temperature at 135 - 165 °C, screw speed 11 rpm, die head temperature 160 °C, to obtain a masterbatch sheet with a thickness of 0.3 mm; then, the masterbatch sheet is irradiated and crosslinked through an electron accelerator, controlling the irradiation dose to be 25 kGy to form a crosslinked polymer network; finally, the crosslinked masterbatch sheet is placed in a foaming furnace for foaming, controlling the foaming furnace temperature to be 180 - 260 °C, and the residence time of the crosslinked masterbatch sheet is 0.3 min, to obtain a highly foamed irradiated crosslinked polypropylene foaming material with an apparent density of 0.065 g / cm 3 , thickness 1 mm, tensile strength 1.9 MPa, elongation at break 240%, permanent compression set 22%, water absorption rate 1.5%, no large bubble holes on the surface, uniform cell structure, cell diameter 0.2 mm, smooth surface, and this polypropylene foam can be used in the field of power battery gaskets.

[0049] Example 2

[0050] Replace the elastomer in step 3 of Example 1 with POE Engage 8842 (Dow, 0.87 g / cm 3 , MI 5.0 g / 10 min), and keep other raw materials and steps the same as in Example 1. The various index parameters of the prepared highly foamed irradiated crosslinked polypropylene foaming material are shown in Table 1.

[0051] Example 3

[0052] Replace the elastomer in step 3 of Example 1 with POE Engage 8840 (Dow, 0.897 g / cm 3 , MI 1.6 g / 10 min), and keep other raw materials and steps the same as in Example 1. The various index parameters of the prepared highly foamed irradiated crosslinked polypropylene foaming material are shown in Table 1.

[0053] Example 4

[0054] Replace the elastomer in step 3 of Example 1 with POP COHERE 8402 (Saudi, 0.902 g / cm 3 , MI 3.5 g / 10 min), and keep other raw materials and steps the same as in Example 1. The various index parameters of the prepared highly foamed irradiated crosslinked polypropylene foaming material are shown in Table 1.

[0055] Example 5

[0056] Replace the elastomer in the third step of Example 1 with POP Queo 1001 (Borealis, 0.91 g / cm 3 , MI 1.1 g / 10 min). Keep other raw materials and steps the same as in Example 1. The index parameters of the high-foamed irradiated crosslinked polypropylene foam material prepared are shown in Table 1.

[0057] Example 6

[0058] Replace the elastomer in the third step of Example 1 with POP Exact 3132F (ExxonMobil, 0.90 g / cm 3 , MI 1.2 g / 10 min). Keep other raw materials and steps the same as in Example 1. The index parameters of the high-foamed irradiated crosslinked polypropylene foam material prepared are shown in Table 1.

[0059] Table 1 Parameters of polypropylene foams prepared with different elastomers

[0060]

[0061] Example 7

[0062] Replace the low-density polyethylene in the third step of Example 1 with LLDPE PP-0118-F (NOVA, Canada, 0.918 g / cm 3 , MI 1.0 g / 10 min). Keep other raw materials and steps the same as in Example 1. The index parameters of the high-foamed irradiated crosslinked polypropylene foam material prepared are shown in Table 2.

[0063] Example 8

[0064] Replace the low-density polyethylene in the third step of Example 1 with LLDPE WPP692D (Southern, USA, 0.918 g / cm 3 , MI 1.0 g / 10 min). Keep other raw materials and steps the same as in Example 1. The index parameters of the high-foamed irradiated crosslinked polypropylene foam material prepared are shown in Table 2.

[0065] Example 9

[0066] Replace the low-density polyethylene in the third step of Example 1 with LLDPE LL1001 (ExxonMobil, 0.918 g / cm 3 , MI 1.0 g / 10 min). Keep other raw materials and steps the same as in Example 1. The index parameters of the high-foamed irradiated crosslinked polypropylene foam material prepared are shown in Table 2.

[0067] Example 10

[0068] Replace the low-density polyethylene in the third step of Example 1 with mLLDPE 5220G (DowDuPont, 0.916 g / cm 3 , MI 3.5 g / 10 min). Keep all other raw materials and steps the same as in Example 1. The parameter indicators of the prepared high-foamed irradiated cross-linked polypropylene foam material are shown in Table 2.

[0069] Table 2 Parameter indicators of polypropylene foams prepared with different low-density polyethylenes

[0070]

[0071] Example 11

[0072] Replace the polypropylene in the third step of Example 1 with PP R3410 (LG of South Korea, 0.9 g / cm 3 , MI 7 g / 10 min). Keep all other raw materials and steps the same as in Example 1. The parameter indicators of the prepared high-foamed irradiated cross-linked polypropylene foam material are shown in Table 3.

[0073] Example 12

[0074] Replace the polypropylene in the third step of Example 1 with PP PC366-3 (Formosa Plastics (FPC), 0.902 g / cm 3 , MI 3.0 g / 10 min). Keep all other raw materials and steps the same as in Example 1. The parameter indicators of the prepared high-foamed irradiated cross-linked polypropylene foam material are shown in Table 3.

[0075] Example 13

[0076] Replace the polypropylene in the third step of Example 1 with PP 4017 (Hanwha Chemical, 0.9 g / cm 3 , MI 8.5 g / 10 min). Keep all other raw materials and steps the same as in Example 1. The parameter indicators of the prepared high-foamed irradiated cross-linked polypropylene foam material are shown in Table 3.

[0077] Example 14

[0078] Replace the polypropylene in the third step of Example 1 with PP H710 (GS of South Korea, 0.903 g / cm 3 , MI 0.7 g / 10 min). Keep all other raw materials and steps the same as in Example 1. The parameter indicators of the prepared high-foamed irradiated cross-linked polypropylene foam material are shown in Table 3.

[0079] Table 3 Parameter indicators of polypropylene foams prepared with different polypropylenes

[0080]

[0081]

[0082] Comparative Example 1

[0083] According to the preparation method of Example 1, without adding ethylene silane modified azodicarbonamide, 40 parts by weight of homopolypropylene (PP PPC 5660, Total, France, 0.905 g / cm 3 , MI 7 g / 10 min), 5 parts by weight of elastomer (POE Engage8842, Dow, 0.857 g / cm 3 , MI (230 °C / 2.16 kg) 1.0 g / 10 min), 15 parts by weight of low density polyethylene (LLDPE4157, DowDuPont, 0.92 g / cm 3 , MI (230 °C / 2.16 kg) 3.0 g / 10 min), 5 parts by weight of liquid polyisoprene (molecular weight about 30000, viscosity 120 Pa·s), 20 parts by weight of montmorillonite intercalated azodicarbonamide, 1.5 parts by weight of zinc benzenesulfinate, 10 parts by weight of flame retardant, 2 parts by weight of antioxidant 1010, added to a screw extruder for plasticizing and extruding a masterbatch sheet, controlling the extrusion temperature at 135 - 165 °C, screw speed 11 rpm, die head temperature 160 °C, to obtain a masterbatch sheet with a thickness of 0.3 mm; then, the masterbatch sheet was irradiated and crosslinked through an electron accelerator, controlling the irradiation dose to be 25 kGy to form a crosslinked polymerization network; finally, the crosslinked masterbatch sheet was placed in a foaming furnace for foaming, controlling the foaming furnace temperature to be 180 - 260 °C, and the residence time of the crosslinked masterbatch sheet was 0.3 min, to obtain an irradiated crosslinked polypropylene foamed material, with an apparent density of 0.075 g / cm 3 , thickness 0.83 mm, tensile strength 0.75 MPa, elongation at break 180%, permanent compression set rate 59%, water absorption rate 2.5%, the uniformity of the cell structure is poor, the pore size distribution is wide, 0.1 - 2 mm, and this polypropylene foam cannot be used in the field of power battery gaskets.

[0084] Comparative Example 2

[0085] According to the preparation method of Example 1, directly use azodicarbonamide, 40 parts by weight of homopolypropylene (PP PPC5660, Total, France, 0.905 g / cm 3 , MI 7 g / 10 min), 5 parts by weight of elastomer (POE Engage 8842, Dow, 0.857 g / cm 3 , MI (230 °C / 2.16 kg) 1.0 g / 10 min), 15 parts by weight of low density polyethylene (LLDPE 4157, DowDuPont, 0.92 g / cm3 , MI (230 °C / 2.16 kg) 3.0 g / 10 min), 5 parts by weight of liquid polyisoprene (molecular weight of about 30,000, viscosity 120 Pa·s), 20 parts by weight of azodicarbonamide, 1.5 parts by weight of zinc benzenesulfinate, 10 parts by weight of flame retardant, 2 parts by weight of antioxidant 1010, were added to a screw extruder for plasticizing and extruding a masterbatch sheet. The extrusion temperature was controlled at 135 - 165 °C, the screw speed was 11 rpm, and the die head temperature was 160 °C to obtain a masterbatch sheet with a thickness of 0.3 mm; then, the masterbatch sheet was irradiated and crosslinked by an electron accelerator, and the irradiation dose was controlled at 25 kGy to form a crosslinked polymer network; finally, the crosslinked masterbatch sheet was placed in a foaming furnace for foaming, the temperature of the foaming furnace was controlled at 180 - 260 °C, and the residence time of the crosslinked masterbatch sheet was 0.3 min to obtain an irradiated crosslinked polypropylene foamed material with an apparent density of 0.092 g / cm 3 , thickness 0.73 mm, tensile strength 0.78 MPa, elongation at break 190%, permanent compression set 61%, water absorption 2.4%, the uniformity of the cell structure was poor, the pore size distribution was wide, 0.3 - 3 mm, and this polypropylene foam could not be used in the field of power battery gaskets.

[0086] The above results prove that the products prepared by the preparation method of the present invention all have good heat resistance, mechanical strength, and long-term adhesiveness, and can be used in the field of power battery gaskets.

[0087] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A radiation cross-linked polypropylene ultrafine pore foam material, characterized in that: The raw materials of the material include, by weight:

2. The radiation cross-linked polypropylene ultrafine pore foam material according to claim 1, characterized in that: The preparation steps of the vinyl silane modified azodicarbonamide are as follows: azodicarbonamide with a particle size of 15 to 30 μm is dispersed in toluene at a mass ratio of 1:10, and then vinyl triethoxysilane is added at a mass ratio of 3 to 15:10 to azodicarbonamide, and reflux reaction is performed for 4 to 24 hours, and then filtered and separated, and vacuum dried to obtain the vinyl silane modified azodicarbonamide.

3. The radiation cross-linked polypropylene ultrafine pore foam material according to claim 1, characterized in that: The preparation steps of the montmorillonite intercalated azodicarbonamide are as follows: fully dispersing sodium montmorillonite in deionized water at a mass ratio of 1:100, stirring for 2 hours to form a slurry; dispersing azodicarbonamide with a particle size of 15 to 30 μm and a mass ratio of 1 to 3:2 with sodium montmorillonite in dimethyl sulfoxide at a mass ratio of 10:1 with the azodicarbonamide, and then adding the azodicarbonamide to the slurry, stirring vigorously at high temperature for 24 hours, centrifuging, and vacuum drying to obtain the montmorillonite intercalated azodicarbonamide.

4. The radiation cross-linked polypropylene ultrafine pore foam material according to claim 1, characterized in that: The elastomer is at least one of EPDM rubber, ethylene-octene copolymer, ethylene-hexene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, natural rubber, isobutyl rubber, styrene-butadiene rubber, styrene-butadiene block copolymer and pentylbenzene block copolymer.

5. The radiation cross-linked polypropylene ultrafine pore foam material according to claim 1, characterized in that: The polypropylene is homopolymer polypropylene, with a melt index of 0.5-5 g / 10 min and a melting point of 145-167° C. The molecular weight of the liquid polyprene is 20,000-70,000, and the viscosity is 50-280 Pa·s. The low-density polyethylene has a density of 0.901-0.922 g / cm 3 , general low-density polyethylene with a melt index of 1 to 6 g / 10 min, and a density of 0.905 to 0.930 g / cm 3 , at least one of linear low-density polyethylenes having a melt index of 0.3 to 5 g / 10 min.

6. The radiation cross-linked polypropylene ultrafine pore foam material according to claim 1, characterized in that: The flame retardant is a composite of decabromodiphenylethane and antimony trioxide, and the mass ratio of the two is 3:1; the antioxidant is at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, butylated hydroxyanisole, dibutylhydroxytoluene, propyl gallate, and tert-butylhydroquinone.

7. The method for preparing the radiation cross-linked polypropylene ultrafine pore foam material according to claim 1, characterized in that: The following steps are involved: (1) mixing polypropylene, elastomer, low-density polyethylene, liquid polyprene, vinyl silane-modified azodicarbonamide, montmorillonite intercalated azodicarbonamide, zinc benzenesulfinate, flame retardant, and antioxidant, and adding the mixture into a screw extruder for mixing and extrusion to obtain a master sheet; (2) The master sheet is subjected to electron irradiation cross-linking, and then the obtained material is subjected to high-temperature foaming treatment to obtain a radiation cross-linked polypropylene ultrafine pore foam material.

8. The preparation method according to claim 7, characterized in that: In the step (1), the extrusion temperature of the screw extruder is 120-170°C, the screw speed is 5-50 rpm, and the die head temperature is 160-180°C.

9. The preparation method according to claim 7, characterized in that: In the step (2), an electron accelerator is used for radiation crosslinking, and the radiation dose of the radiation crosslinking is 4 to 40 kGy; the high-temperature foaming treatment is carried out in a foaming furnace, the temperature of the foaming furnace is 180 to 280° C., and the foaming time is 0.1 to 3 minutes.

10. Use of the radiation cross-linked polypropylene ultrafine pore foam material according to claim 1 in the preparation of power battery gaskets.

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