Compression-resistant heat-insulating buffer cotton and preparation method thereof

Abstract

This invention belongs to the field of polymer foaming materials technology, specifically relating to a pressure-resistant and heat-insulating cushioning cotton and its preparation method. The invention uses low-density polyethylene (LDPE) as the main component, providing good melt ductility for foaming and facilitating cell growth and molding. High-density polyethylene (HDPE) is added as a reinforcing phase, bearing and dispersing compressive stress within the LPE. Toughening agents absorb crack energy in the cushioning cotton through an anchoring effect, improving the cotton's strength and impact resistance. Azodicarbonamide is intercalated between montmorillonite layers through ball milling, and then encapsulated with epoxy resin to obtain a composite foaming agent. Montmorillonite acts as a heterogeneous nucleation site, refining the cell structure. Staged heating controls the gas production rate, avoiding the problems of bursting and uneven cell size caused by concentrated gas production in a single event. The cushioning cotton prepared by this invention exhibits excellent heat and pressure resistance, solving the problem of softening and shrinkage leading to cushioning failure in areas near heat sources.

Description

Technical Field

[0001] This invention belongs to the field of polymer foaming materials technology, specifically relating to a pressure-resistant and heat-insulating cushioning cotton and its preparation method. Background Technology

[0002] Cushioning foam is a type of elastic material with a porous structure and deformation recovery capability. It absorbs and disperses impact force through its own deformation to mitigate vibration, and is therefore commonly used in packaging, construction, and automotive cushioning and insulation. Existing polyethylene cushioning foam suffers from low strength and insufficient heat resistance. Insufficient heat resistance makes the foam structure more prone to irreversible collapse, creating internal voids and cracks, severely affecting its mechanical properties and durability, and compromising its impact-resistant performance. Therefore, current technologies often address these issues by altering the composition of the cushioning foam matrix.

[0003] Chinese invention patent CN110216958B discloses a low thermal conductivity, tensile and compressive resistant multilayer foamed material and its preparation method. The multilayer foamed material is composed of alternating foamed layers and solid layers. The solid layer is a single polyolefin material, while the foamed layer is a blend of two polyolefin materials. The preparation method involves adding a mixture of polypropylene and ethylene-octene copolymer with low-density polyethylene to two extruders. The melts extruded from the two extruders are compounded in a co-extrusion die head, and after passing through a layer multiplier, multiple layers are stacked. The multilayer melt is then shaped to obtain a micro-sheet of alternating PP / (POE / LDPE) layers. Utilizing the difference in melting temperature between the PP and POE / LDPE blends, the multilayer foamed material with alternating foamed and solid layers is prepared through intermittent foaming. This foamed material exhibits high thermal insulation and mechanical properties, and its low cost expands the application of polyolefins in packaging, thermal insulation, and sound insulation materials. However, existing technologies have a technical problem: they do not improve the cushioning cotton's pressure resistance and heat insulation performance by modifying the additives used in the cushioning cotton. Summary of the Invention

[0004] The purpose of this invention is to provide a pressure-resistant and heat-insulating cushioning cotton and its preparation method, in order to solve the technical problem in the prior art that the cushioning cotton has not been improved by modifying the additives to enhance its pressure resistance and heat insulation performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A pressure-resistant and heat-insulating cushioning cotton is made from the following raw materials in parts by weight: 100 parts low-density polyethylene resin, 10-15 parts high-density polyethylene resin, 15-25 parts ethylene-vinyl acetate copolymer, 1-3 parts toughening agent, 0.5-2 parts antioxidant, 0.5-3 parts crosslinking agent and 1-5 parts composite foaming agent.

[0006] The antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076; The crosslinking agent is dicumyl peroxide.

[0007] The preparation method of the toughening agent includes the following steps: S11. Add zinc ethanol and zinc nitrate to N-N' dimethylformamide, add P-123 dropwise, and electrospin to obtain precursor fibers. Add the precursor fibers to a muffle furnace for calcination to obtain zinc oxide fibers. S12. Add zinc oxide fiber to ethanol and ultrasonically stir to disperse it. Add KH-581 and deionized water, heat to modify the reaction, filter to collect the solid, wash with deionized water and ethanol in sequence, and dry to obtain toughening agent.

[0008] Preferably, the mass ratio of zinc ethoxide, zinc nitrate, NN, dimethylformamide, and P-123 in S11 is 1.5~2:2~3:30~50:1~1.5, and the mixture is heated to 550~570℃ at a rate of 1.5~2.5℃ / min and calcined for 2~4 hours.

[0009] Preferably, the mass ratio of zinc oxide fiber, ethanol, kH-581 and deionized water in S12 is 5~6:10~20:1~3:20~40. The mixture is ultrasonically dispersed at a power of 30~50W for 10~20 minutes, heated to 50~60℃ for 1~2 hours, and then dried at 50~60℃.

[0010] The preparation method of the composite foaming agent includes the following steps: S21. Azodiamide Dn6, azodiamide Dn15, carboxymethyl cellulose, montmorillonite and deionized water are added to a ball mill and ball-milled, then dried at room temperature to obtain a mixture. S22. Add the mixture to the reactor, add ethanol and stir to disperse evenly, add epoxy resin and stir, and finally add triethylenetetramine curing agent to cure, filter to collect the solid, wash with deionized water, and dry at room temperature to obtain composite foaming agent.

[0011] Preferably, in S21, the mass ratio of azodiamide Dn6, azodiamide Dn15, carboxymethyl cellulose, montmorillonite, and deionized water is 20~25:10~15:0.1~0.2:2~5:10~20, the grinding balls in the ball mill are stainless steel balls, the ball-to-material ratio is 10~15:1, and the ball milling is carried out at a speed of 500~800 rpm for 4~6 hours.

[0012] Preferably, in step S22, the mass ratio of the mixture, ethanol, epoxy resin, and triethylenetetramine curing agent is 100:50~70:30~40:3~5. After adding ethanol, the mixture is stirred at 1000~2000 rpm for 10~20 min. After adding epoxy resin, the mixture is stirred at 300~500 rpm for 20~30 min. Finally, the triethylenetetramine curing agent is added and the temperature is raised to 50~60℃ for curing for 4~6 h.

[0013] A method for preparing a pressure-resistant and heat-insulating cushioning cotton includes the following steps: S1. Polyethylene resin, nano toughening agent, antioxidant and crosslinking agent are added to a high-speed mixer and mixed. Then, the mixture is added to a kneader and heated to knead to obtain kneaded rubber. The kneaded rubber is added to an extruder for extrusion granulation, heated to crosslink, and cooled to obtain crosslinked polyethylene masterbatch. S2. After mixing cross-linked polyethylene masterbatch, ethylene-vinyl acetate copolymer and foaming agent, the mixture is added to an extruder and heated to extrude and obtain master sheet. The master sheet is then added to a foaming machine and heated to foam, and degassed and cooled to obtain pressure-resistant and heat-insulating cushioning cotton.

[0014] Preferably, the high-speed mixer in S1 is stirred at a speed of 1000~2000 rpm for 30~50 min, heated to 60~70℃ and kneaded for 8~13 min, the feeding speed is 0.5~0.6 kg / h, the main screw speed is 40~50 rpm, and the temperature settings of each temperature zone of the extruder are as follows: die head 140~150℃, zone 1 90~100℃, zone 2 110~120℃, zone 3 130~140℃, zone 4 140~150℃, zone 5 140~150℃, zone 6 145~155℃, and crosslinked at 160~180℃ for 10~20 min.

[0015] Preferably, the temperature settings of each temperature zone of the extruder in S2 are as follows: die head 120~140℃, zone 1 110~120℃, zone 2 110~120℃, zone 3 120~130℃, zone 4 130~135℃, zone 5 135~145℃, zone 6 130~140℃. The foaming machine is heated to 150~160℃ at a pressure of 10~15MPa for 5~10 minutes, then heated to 160~170℃ for 5~10 minutes, and degassed at 70~80℃ for 20~24 hours.

[0016] An application of a pressure-resistant and heat-insulating cushioning cotton for use as a shock-absorbing layer in packaging boxes.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention uses low-density polyethylene (LDPE) as the main component, providing good melt ductility for foaming and facilitating cell growth and molding. The addition of ethylene-vinyl acetate copolymer improves the interfacial compatibility of LPE, and the inclusion of high-density polyethylene (HDPE) as a reinforcing phase enhances the compressive strength and dimensional stability of the cushioning cotton by bearing and dispersing compressive stress within the LPE, preventing permanent deformation under pressure. The cushioning cotton produced by this invention exhibits excellent heat and pressure resistance, solving the problem of softening and shrinking near heat sources, leading to cushioning failure.

[0018] 2. The present invention uses zinc oxide fibers obtained by electrospinning and then modifies the surface with kH-581 to obtain a toughening agent, which introduces octyl groups, thereby improving the dispersibility of zinc oxide fibers in the cushioning cotton. In the cushioning cotton, the fiber absorbs crack energy through the anchoring effect, thereby improving the strength and impact resistance of the cushioning cotton. The fiber steric hindrance inhibits the size of the foamed cells, making the resulting cushioning cotton have a uniform distribution of cells. The refined cells restrict the air flow inside the cushioning cotton, thereby improving the thermal insulation performance of the cushioning cotton.

[0019] 3. This invention uses ball milling to intercalate azodiamide particles of different sizes between montmorillonite particles, and then encapsulates them with epoxy resin to obtain a composite foaming agent. Montmorillonite serves as a heterogeneous nucleation site, inducing gas to nucleate at more sites, thereby significantly refining the pores and increasing the pore density. By using azodiamide particles of different sizes in combination, the gas production rate is controlled by staged heating, avoiding the problems of bursting pores and uneven pore size caused by single concentrated gas production. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The low-density polyethylene resin involved in this invention is designated as LD100AC, the high-density polyethylene resin as HE1878, the acetic acid content of the ethylene-vinyl acetate copolymer is 18wt%, and the epoxy resin is designated as E44.

[0022] Example 1: A pressure-resistant and heat-insulating cushioning cotton of this example is made from the following raw materials: 100g of low-density polyethylene resin, 10g of high-density polyethylene resin, 15g of ethylene-vinyl acetate copolymer, 1g of toughening agent, 1g of antioxidant, 2g of crosslinking agent and 4g of composite foaming agent.

[0023] The antioxidant is prepared by mixing antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2; The crosslinking agent is dicumyl peroxide.

[0024] The preparation method of the toughening agent in this embodiment includes the following steps: S11. Add 1.5g of zinc ethanol and 2.5g of zinc nitrate to 50g of N-N'-dimethylformamide, add 1.5g of P-123 dropwise, and electrospin to obtain precursor fibers. Add the precursor fibers to a muffle furnace and calcine at 550℃ for 2h at a rate of 1.5℃ / min to obtain zinc oxide fibers. S12. Add 5g of zinc oxide fiber to 20g of ethanol and ultrasonically stir and disperse for 10min at 50W power. Add 3g of kH-581 and 40g of deionized water, heat to 60℃ for 2h for modification reaction, filter to collect solid, wash with deionized water and ethanol in sequence, and heat to 60℃ to dry to obtain toughening agent.

[0025] The preparation method of the composite foaming agent in this embodiment includes the following steps: S21. Add 20g of azodiamide Dn6, 10g of azodiamide Dn15, 0.2g of carboxymethyl cellulose, 2.5g of montmorillonite and 20g of deionized water to a ball mill. The grinding balls are stainless steel balls with a ball-to-material ratio of 15:1. The mixture is ball-milled at 500rpm for 4 hours and then dried at room temperature to obtain a mixture. S22. Add 100g of the mixture to the reactor, add 50g of ethanol and stir at 1000rpm for 10min to disperse evenly, add 30g of epoxy resin and stir at 300rpm for 20min, finally add 3g of triethylenetetramine curing agent and heat to 50℃ to cure for 4h, filter to collect the solid, wash with deionized water, and dry at room temperature to obtain the composite foaming agent.

[0026] The method for preparing a pressure-resistant and heat-insulating cushioning cotton according to this embodiment includes the following steps: S1. Polyethylene resin, nano toughening agent, antioxidant, and crosslinking agent are added to a high-speed mixer and stirred at 1000 rpm for 30 minutes. Then, the mixture is added to an internal mixer and heated to 60°C for 8 minutes to obtain an internally mixed rubber. The internally mixed rubber is added to an extruder for granulation. The feeding speed is 0.5 kg / h, the main screw speed is 40 rpm, and the temperature settings of each zone of the extruder are as follows: die head 140°C, zone 1 90°C, zone 2 110°C, zone 3 130°C, zone 4 140°C, zone 5 140°C, zone 6 145°C. The mixture is then heated to 160°C and crosslinked for 10 minutes. After cooling, crosslinked polyethylene masterbatch is obtained. S2. After mixing the cross-linked polyethylene masterbatch, ethylene-vinyl acetate copolymer and foaming agent, the mixture is added to the extruder. The temperature settings of each zone of the extruder are as follows: die head 130℃, zone 1 110℃, zone 2 120℃, zone 3 120℃, zone 4 130℃, zone 5 135℃, zone 6 130℃. The masterbatch is extruded to obtain a masterbatch. The masterbatch is added to a foaming machine. The foaming machine is heated to 150℃ at a pressure of 10MPa for 5 minutes, then heated to 160℃ for 5 minutes. The masterbatch is degassed at 70℃ for 24 hours and cooled to obtain a pressure-resistant and heat-insulating cushioning cotton.

[0027] Example 2: A pressure-resistant and heat-insulating cushioning cotton of this example is made from the following raw materials: 100g of low-density polyethylene resin, 12g of high-density polyethylene resin, 16g of ethylene-vinyl acetate copolymer, 1.5g of toughening agent, 0.5g of antioxidant, 1g of crosslinking agent and 1.5g of composite foaming agent.

[0028] The antioxidant is antioxidant 1010; The crosslinking agent is dicumyl peroxide.

[0029] The preparation method of the toughening agent in this embodiment includes the following steps: S11. Add 1.5g of zinc ethanol and 2g of zinc nitrate to 50g of N-N'-dimethylformamide, add 1g of P-123 dropwise, and electrospin to obtain precursor fibers. Add the precursor fibers to a muffle furnace and calcine at a rate of 2℃ / min to 560℃ for 2.5h to obtain zinc oxide fibers. S12. Add 6g of zinc oxide fiber to 10g of ethanol and ultrasonically stir and disperse for 10min at 30W power. Add 3g of kH-581 and 30g of deionized water, heat to 60℃ for 1h for modification reaction, filter to collect solid, wash with deionized water and ethanol in sequence, and heat to 50℃ to dry to obtain toughening agent.

[0030] The preparation method of the composite foaming agent in this embodiment includes the following steps: S21. Add 20g of azodiamide Dn6, 15g of azodiamide Dn15, 0.15g of carboxymethyl cellulose, 3g of montmorillonite and 20g of deionized water to a ball mill. The grinding balls are stainless steel balls with a ball-to-material ratio of 13:1. The mixture is ball-milled at 600 rpm for 6 hours and then dried at room temperature to obtain a mixture. S22. Add 100g of the mixture to the reactor, add 60g of ethanol and stir at 1500rpm for 15min to disperse evenly, add 35g of epoxy resin and stir at 300rpm for 25min, finally add 4g of triethylenetetramine curing agent and heat to 50℃ to cure for 5h, filter to collect the solid, wash with deionized water, and dry at room temperature to obtain the composite foaming agent.

[0031] The method for preparing a pressure-resistant and heat-insulating cushioning cotton according to this embodiment includes the following steps: S1. Polyethylene resin, nano toughening agent, antioxidant, and crosslinking agent are added to a high-speed mixer and stirred at 1500 rpm for 35 minutes. Then, the mixture is added to an internal mixer and heated to 65°C for 10 minutes to obtain an internally mixed rubber. The internally mixed rubber is added to an extruder for extrusion and granulation. The feeding speed is 0.55 kg / h, the main screw speed is 45 rpm, and the temperature settings of each zone of the extruder are as follows: die head 150°C, zone 1 100°C, zone 2 120°C, zone 3 140°C, zone 4 150°C, zone 5 150°C, zone 6 155°C. The mixture is then heated to 180°C and crosslinked for 20 minutes. After cooling, crosslinked polyethylene masterbatch is obtained. S2. After mixing the cross-linked polyethylene masterbatch, ethylene-vinyl acetate copolymer and foaming agent, the mixture is added to the extruder. The temperature settings of each zone of the extruder are as follows: die head 140℃, zone 1 120℃, zone 2 120℃, zone 3 130℃, zone 4 135℃, zone 5 145℃, zone 6 140℃. The masterbatch is extruded to obtain a master sheet. The master sheet is added to a foaming machine. The foaming machine is heated to 155℃ at a pressure of 15MPa for 10 minutes, then heated to 160℃ for 8 minutes. The foaming is then degassed at 75℃ for 20 hours and cooled to obtain a pressure-resistant and heat-insulating cushioning cotton.

[0032] Example 3: A pressure-resistant and heat-insulating cushioning cotton of this example is made from the following raw materials: 100g of low-density polyethylene resin, 14g of high-density polyethylene resin, 20g of ethylene-vinyl acetate copolymer, 2g of toughening agent, 1.5g of antioxidant, 3g of crosslinking agent and 2g of composite foaming agent.

[0033] The antioxidant is prepared by mixing antioxidant 1010 and antioxidant 1076 in a mass ratio of 1:1; The crosslinking agent is dicumyl peroxide.

[0034] The preparation method of the toughening agent in this embodiment includes the following steps: S11. Add 2g of zinc ethanol and 3g of zinc nitrate to 50g of N-N'-dimethylformamide, add 1g of P-123 dropwise, and electrospin to obtain precursor fibers. Add the precursor fibers to a muffle furnace and calcine at a rate of 2.5℃ / min to 570℃ for 4h to obtain zinc oxide fibers. S12. Add 5g of zinc oxide fiber to 10g of ethanol and ultrasonically disperse it for 10min at 40W. Add 1.5g of KH-581 and 20g of deionized water, heat to 60℃ for 2h for modification reaction, filter to collect solid, wash with deionized water and ethanol in sequence, and heat to 60℃ to dry to obtain toughening agent.

[0035] The preparation method of the composite foaming agent in this embodiment includes the following steps: S21. Add 23g of azodiamide Dn6, 13g of azodiamide Dn15, 0.2g of carboxymethyl cellulose, 5g of montmorillonite and 15g of deionized water to a ball mill. The grinding balls are stainless steel balls with a ball-to-material ratio of 11:1. The mixture is ball-milled at 500 rpm for 6 hours and then dried at room temperature to obtain a mixture. S22. Add 100g of the mixture to the reactor, add 70g of ethanol and stir at 2000rpm for 10min to disperse evenly, add 40g of epoxy resin and stir at 500rpm for 20min, finally add 5g of triethylenetetramine curing agent and heat to 50℃ for 6h to cure, filter to collect the solid, wash with deionized water and dry at room temperature to obtain the composite foaming agent.

[0036] The method for preparing a pressure-resistant and heat-insulating cushioning cotton according to this embodiment includes the following steps: S1. Polyethylene resin, nano toughening agent, antioxidant, and crosslinking agent are added to a high-speed mixer and stirred at 2000 rpm for 30 minutes. Then, the mixture is added to an internal mixer and heated to 60°C for 13 minutes to obtain an internally mixed rubber. The internally mixed rubber is added to an extruder for granulation. The feeding speed is 0.6 kg / h, the main screw speed is 50 rpm, and the temperature settings of each zone of the extruder are as follows: die head 145°C, zone 1 95°C, zone 2 115°C, zone 3 130°C, zone 4 140°C, zone 5 145°C, zone 6 150°C. The mixture is then heated to 170°C and crosslinked for 15 minutes. After cooling, crosslinked polyethylene masterbatch is obtained. S2. After mixing the cross-linked polyethylene masterbatch, ethylene-vinyl acetate copolymer and foaming agent, the mixture is added to the extruder. The temperature settings of each zone of the extruder are as follows: die head 130℃, zone 1 115℃, zone 2 120℃, zone 3 130℃, zone 4 135℃, zone 5 135℃, zone 6 130℃. The masterbatch is extruded to obtain a masterbatch. The masterbatch is added to a foaming machine. The foaming machine is heated to 160℃ at a pressure of 13MPa for 5 minutes, then heated to 170℃ for 10 minutes. The masterbatch is degassed at 80℃ for 24 hours and cooled to obtain a pressure-resistant and heat-insulating cushioning cotton.

[0037] Example 4: A pressure-resistant and heat-insulating cushioning cotton of this example is made from the following raw materials: 100g of low-density polyethylene resin, 10g of high-density polyethylene resin, 25g of ethylene-vinyl acetate copolymer, 2.5g of toughening agent, 1.5g of antioxidant, 3g of crosslinking agent and 3g of composite foaming agent.

[0038] The antioxidant is prepared by mixing antioxidant 1010 and antioxidant 1076 in a mass ratio of 1:1; The crosslinking agent is dicumyl peroxide.

[0039] The preparation method of the toughening agent in this embodiment includes the following steps: S11. Add 1.5g of zinc ethanol and 3g of zinc nitrate to 30g of N-N'-dimethylformamide, add 1g of P-123 dropwise, and electrospin to obtain precursor fibers. Add the precursor fibers to a muffle furnace and calcine at a rate of 1.5℃ / min to 570℃ for 2h to obtain zinc oxide fibers. S12. Add 5g of zinc oxide fiber to 15g of ethanol and ultrasonically disperse it for 10min at 50W. Add 2.5g of KH-581 and 30g of deionized water, heat to 50℃ and modify for 2h. Filter and collect the solid, wash it with deionized water and ethanol in sequence, and dry it at 50℃ to obtain the toughening agent.

[0040] The preparation method of the composite foaming agent in this embodiment includes the following steps: S21. Add 25g of azodiamide Dn6, 10g of azodiamide Dn15, 0.1g of carboxymethyl cellulose, 3g of montmorillonite and 15g of deionized water to a ball mill. The grinding balls are stainless steel balls with a ball-to-material ratio of 14:1. The mixture is ball-milled at 800rpm for 6 hours and then dried at room temperature to obtain a mixture. S22. Add 100g of the mixture to the reactor, add 55g of ethanol and stir at 1000rpm for 15min to disperse evenly, add 30g of epoxy resin and stir at 500rpm for 30min, finally add 5g of triethylenetetramine curing agent and heat to 50℃ for 6h to cure, filter to collect the solid, wash with deionized water and dry at room temperature to obtain the composite foaming agent.

[0041] The method for preparing a pressure-resistant and heat-insulating cushioning cotton according to this embodiment includes the following steps: S1. Polyethylene resin, nano toughening agent, antioxidant, and crosslinking agent are added to a high-speed mixer and stirred at 2000 rpm for 50 minutes. Then, the mixture is added to an internal mixer and heated to 70°C for 8 minutes to obtain an internally mixed rubber. The internally mixed rubber is added to an extruder for granulation. The feeding speed is 0.6 kg / h, the main screw speed is 50 rpm, and the temperature settings of each zone of the extruder are as follows: die head 140°C, zone 1 100°C, zone 2 110°C, zone 3 135°C, zone 4 145°C, zone 5 150°C, zone 6 155°C. The mixture is then heated to 170°C and crosslinked for 15 minutes. After cooling, crosslinked polyethylene masterbatch is obtained. S2. After mixing the cross-linked polyethylene masterbatch, ethylene-vinyl acetate copolymer and foaming agent, the mixture is added to the extruder. The temperature settings of each zone of the extruder are as follows: die head 135℃, zone 1 110℃, zone 2 115℃, zone 3 120℃, zone 4 135℃, zone 5 140℃, zone 6 140℃. The masterbatch is extruded to obtain a masterbatch. The masterbatch is added to a foaming machine. The foaming machine is heated to 150℃ at a pressure of 10MPa for 5 minutes, then heated to 170℃ for 10 minutes. The masterbatch is degassed at 75℃ for 24 hours and cooled to obtain a pressure-resistant and heat-insulating cushioning cotton.

[0042] Comparative Example 1 differs from Example 1 in that it does not contain high-density polyethylene.

[0043] Comparative Example 2 differs from Example 1 in that the toughening agent is replaced with zinc oxide powder with an average particle size of 30 μm.

[0044] Comparative Example 3 differs from Example 1 in that the composite foaming agent is replaced with azodicarbonamide Dn15.

[0045] Performance testing The compressive strength of the cushioning cotton prepared in each example and comparative example was measured according to GB / T 8813-2020 "Determination of compressive properties of rigid foamed plastics" at 50% compression relative deformation.

[0046] According to GB / T 6343-2009 "Determination of Apparent Density of Foamed Plastics and Rubber", the actual density of the cushioning cotton prepared in each example and comparative example was measured, and the average cell diameter of the cushioning cotton prepared in each example and comparative example was observed and statistically analyzed.

[0047] The thermal conductivity of the buffer cotton prepared in each embodiment and comparative example was measured according to GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Heat Flow Meter Method".

[0048] The test results are shown in Table 1 below: Table 1 Test Results As shown in Table 1, the compressive strength of the cushioning cotton prepared in Examples 1-4 under 50% compression relative deformation is 1.86-3.21 MPa, indicating that the cushioning cotton prepared by this invention has excellent compressive strength. The actual density of the cushioning cotton prepared in Examples 1-4 is 25.64-25.73 kg / m³. 3 The average cell diameter was 1042~1083 μm. In Comparative Example 3, the composite foaming agent was replaced with azodicarbonamide Dn15, which caused concentrated gas generation during the foaming stage, resulting in bursting cells. The average cell diameter of this example was 1564 μm, indicating that the present invention can refine the cell diameter of the prepared cushioning cotton. The thermal conductivity of the cushioning cotton prepared in Examples 1~4 was 0.075~0.083 W×K.-1 ×m -1 This demonstrates that the cushioning cotton prepared by this invention has excellent heat insulation properties.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0050] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A pressure-resistant and heat-insulating cushioning cotton, characterized in that, It is prepared from the following raw materials in parts by weight: 100 parts low-density polyethylene resin, 10-15 parts high-density polyethylene resin, 15-25 parts ethylene-vinyl acetate copolymer, 1-3 parts toughening agent, 0.5-2 parts antioxidant, 0.5-3 parts crosslinking agent and 1-5 parts composite foaming agent.

2. The pressure-resistant and heat-insulating cushioning cotton according to claim 1, characterized in that, The antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076; the crosslinking agent is dicumyl peroxide.

3. The pressure-resistant and heat-insulating cushioning cotton according to claim 1, characterized in that, The preparation method of the toughening agent includes the following steps: S11. Add zinc ethanol and zinc nitrate to N-N' dimethylformamide, add P-123 dropwise, and electrospin to obtain precursor fibers. Add the precursor fibers to a muffle furnace for calcination to obtain zinc oxide fibers. S12. Add zinc oxide fiber to ethanol and ultrasonically stir to disperse it. Add KH-581 and deionized water, heat to modify the reaction, filter to collect the solid, wash with deionized water and ethanol in sequence, and dry to obtain toughening agent.

4. The pressure-resistant and heat-insulating cushioning cotton according to claim 3, characterized in that, In S11, the mass ratio of zinc ethoxide, zinc nitrate, NN, dimethylformamide, and P-123 is 1.5~2:2~3:30~50:1~1.5, and the mixture is calcined at 550~570℃ for 2~4 hours at a rate of 1.5~2.5℃ / min. In S12, the mass ratio of zinc oxide fiber, ethanol, kH-581, and deionized water is 5~6:10~20:1~3:20~40, and the mixture is ultrasonically dispersed at 30~50W for 10~20 minutes, reacted at 50~60℃ for 1~2 hours, and then dried at 50~60℃.

5. The pressure-resistant and heat-insulating cushioning cotton according to claim 1, characterized in that, The preparation method of the composite foaming agent includes the following steps: S21. Azodiamide Dn6, azodiamide Dn15, carboxymethyl cellulose, montmorillonite and deionized water are added to a ball mill and ball-milled, then dried at room temperature to obtain a mixture. S22. Add the mixture to the reactor, add ethanol and stir to disperse evenly, add epoxy resin and stir, and finally add triethylenetetramine curing agent to cure, filter to collect the solid, wash with deionized water, and dry at room temperature to obtain composite foaming agent.

6. The pressure-resistant and heat-insulating cushioning cotton according to claim 5, characterized in that, In S21, the mass ratio of azodiamide Dn6, azodiamide Dn15, carboxymethyl cellulose, montmorillonite, and deionized water is 20~25:10~15:0.1~0.2:2~5:10~20. The grinding balls in the ball mill are stainless steel balls, and the ball-to-material ratio is 10~15:

1. The milling is carried out at a speed of 500~800 rpm for 4~6 hours. In S22, the mass ratio of the mixture, ethanol, epoxy resin, and triethylenetetramine curing agent is 100:50~70:30~40:3~5. After adding ethanol, the mixture is stirred at a speed of 1000~2000 rpm for 10~20 minutes. After adding epoxy resin, the mixture is stirred at a speed of 300~500 rpm for 20~30 minutes. Finally, the triethylenetetramine curing agent is added, and the temperature is raised to 50~60℃ for curing for 4~6 hours.

7. A method for preparing a pressure-resistant and heat-insulating cushioning cotton according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Polyethylene resin, nano toughening agent, antioxidant and crosslinking agent are added to a high-speed mixer and mixed. Then, the mixture is added to a kneader and heated to knead to obtain kneaded rubber. The kneaded rubber is added to an extruder for extrusion granulation, heated to crosslink, and cooled to obtain crosslinked polyethylene masterbatch. S2. After mixing cross-linked polyethylene masterbatch, ethylene-vinyl acetate copolymer and foaming agent, the mixture is added to an extruder and heated to extrude and obtain master sheet. The master sheet is then added to a foaming machine and heated to foam, and degassed and cooled to obtain pressure-resistant and heat-insulating cushioning cotton.

8. The method for preparing a pressure-resistant and heat-insulating cushioning cotton according to claim 7, characterized in that, The S1 high-speed mixer stirs at 1000-2000 rpm for 30-50 minutes, then heats to 60-70℃ and kneads for 8-13 minutes. The feeding rate is 0.5-0.6 kg / h, and the main screw speed is 40-50 rpm. The temperature settings for each zone of the extruder are as follows: die head 140-150℃, zone 1 90-100℃, zone 2 110-120℃, zone 3 130-140℃, zone 4 140-150℃, zone 5 140-150℃, zone 6 145-155℃, and then heats to 160℃. Crosslinking at 180℃ for 10-20 min; the temperature settings of each zone of the extruder in S2 are as follows: die head 120-140℃, zone 1 110-120℃, zone 2 110-120℃, zone 3 120-130℃, zone 4 130-135℃, zone 5 135-145℃, zone 6 130-140℃. The foaming machine is heated to 150-160℃ at a pressure of 10-15MPa for 5-10 min, then heated to 160-170℃ for 5-10 min, and degassed at 70-80℃ for 20-24 h.

9. The application of the compression-resistant and heat-insulating cushioning cotton according to any one of claims 1-6, characterized in that, Used as a shock-absorbing layer for packaging boxes.

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