Low-temperature-resistant and low-heat-conductivity door sealing material, preparation method thereof and door sealing strip

Abstract

The invention discloses a low-temperature-resistant and low-thermal-conductivity door seal material, a preparation method thereof and a door seal strip, and relates to the technical field of low-thermal-conductivity door seal materials, the low-temperature-resistant and low-thermal-conductivity door seal material comprises a modified PVC base material and an expansion master batch; the modified PVC base material comprises PVC, a plasticizer, an elastomer, a stabilizer, a first lubricant, an antibacterial mildew inhibitor and GMA-SEBS-EVA; the expansion master batch comprises a polyolefin compound, expansion microspheres, an antioxidant, a dispersion compatilizer and a second lubricant; the door seal material prepared by the invention not only has excellent low temperature resistance and low heat-conducting property, but also has the advantages of high strength, high toughness, stable and controllable expansion, few defects, smaller and denser organic expansion microspheres, smoother surface and the like, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of door sealing materials, and in particular relates to a low-temperature resistant and low-heat conductive sealing material, a preparation method thereof, and a door sealing strip. Background Art

[0002] With increasing societal demands for energy conservation and environmental protection, the production of low-thermal-conductivity door seal materials has become a necessary industry trend. Traditional door seals primarily utilize polyvinyl chloride (PVC) and ethylene-vinyl acetate copolymer (EVA) as their base materials. Insulation is achieved by adding hollow glass microspheres, silicates, and organic expanded microspheres to reduce the seal's thermal conductivity. Furthermore, due to the increasing use of door seals in refrigeration equipment such as refrigerators and freezers, these seals must not only provide insulation but also withstand low-temperature conditions. To improve the low-temperature resistance of door seals, existing technologies have explored methods such as the addition of low-temperature-resistant materials such as styrene-ethylene-butylene-styrene block copolymer (SEBS) and thermoplastic polyurethane (TPU).

[0003] However, existing technologies have significant defects in the following two aspects: First, the PVC / EVA matrix has poor compatibility with modified materials such as styrene-ethylene-butylene-styrene block copolymer (SEBS), resulting in weak interfacial bonding of the composite material and susceptibility to brittle cracking in low-temperature environments; second, because conventional compatibilizers are difficult to coordinate multiphase systems, this can lead to the appearance of microbeads, uneven material dispersion, and a high breakage rate of organic expanded microspheres during product processing, and the density, strength, and thermal conductivity of the door seal material cannot be stabilized.

[0004] Patent application number CN118146595A, "Refrigeration Appliance Door Seal Material, Preparation Method, and Application thereof," describes a refrigeration appliance door seal material with excellent strength and low thermal conductivity. The material is prepared by preparing a modified PVC base material and an expansion masterbatch, employing low-temperature masterbatch carrier technology. The modified PVC base material is modified by adding maleic anhydride-grafted SEBS to the PVC base material. The modified PVC base material is then mixed with the low-temperature masterbatch carrier. However, the product becomes hard and brittle at low temperatures, significantly limiting its application in low-temperature environments. Therefore, there is an urgent need to develop a low-temperature-resistant, low-conductivity door seal material with strong interfacial bonding, high low-temperature toughness, and a smooth, defect-free surface to meet the needs of low-temperature applications. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-temperature resistant, low-conductivity thermal sealing material, a preparation method thereof, and a door seal strip, so as to solve the problems existing in the prior art such as weak interface bonding of composite materials, easy brittle cracking under low-temperature conditions, and high breakage rate of microbeads and organic expanded microspheres during processing.

[0006] The purpose of the present invention can be achieved through the following technical solutions: The present invention provides a low-temperature resistant, low-conductivity thermal sealing material, comprising a modified PVC base material and an expansion masterbatch, wherein the modified PVC base material comprises PVC, a plasticizer, an elastomer, a stabilizer, a first lubricant, an antibacterial and mildew-proof agent, and GMA-SEBS-EVA; the expansion masterbatch comprises a polyolefin compound, expansion microspheres, an antioxidant, a dispersing compatibilizer, and a second lubricant; The GMA-SEBS-EVA comprises the following raw materials in parts by weight: 180-200 parts of SEBS, 8-12 parts of EVA, 18-20 parts of GMA, 2-3.5 parts of initiator, 0.4-1.2 parts of lubricant, and 0.8-1.8 parts of antioxidant; Furthermore, the GMA-SEBS-EVA comprises the following preparation steps: S1, weighed 1.2-2.2 parts by mass of initiator, 0.3-0.8 parts by mass of lubricant, 0.5-1.1 parts by mass of antioxidant; SEBS and initiator were added to the solvent, heated to 70-85 ° C, stirred and mixed for 8-10min, GMA, lubricant and antioxidant were added, stirring and mixing was continued for 10-15min, heated to 80-120 ° C for 3-6h to obtain a mixture A; S2, weighing 0.8-1.3 parts by mass of initiator, 0.1-0.4 parts by mass of lubricant, 0.3-0.7 parts by mass of antioxidant; heating the mixture A and the initiator to 75-90 ° C, stirring and mixing for 6-8 min, adding EVA, lubricant and antioxidant, continuing to stir and mix for 12-18 min, heating to 90-140 ° C for 2-5 h to obtain a mixture B; S3, adding mixture B into a twin-screw extruder for melt blending, extrusion and granulation to obtain a GMA-SEBS-EVA finished product; Furthermore, the initiator is one of di-tert-butyl peroxide, dicumyl peroxide and dibenzoyl peroxide; Furthermore, the lubricant is one or more of ethylene bisstearamide, solid paraffin and polyethylene wax; Furthermore, the antioxidant is one or more of antioxidant 1010, antioxidant 1035 and antioxidant 1076; Furthermore, in the modified PVC base material, relative to 100 parts by weight of PVC, the plasticizer is 50-90 parts, the elastomer is 5-20 parts, the stabilizer is 1-5 parts, the first lubricant is 0.2-1 parts, the antibacterial and mildewproof agent is 0.2-2 parts, and the GMA-SEBS-EVA is 0.1-0.5 parts; Further, in the expanding masterbatch, relative to 100 parts by weight of the polyolefin compound, the expanding microspheres are 40-120 parts, the antioxidant is 0.2-1 parts, the second lubricant is 0.2-1 parts, the dispersing compatibilizer is 0.2-1 parts; Further, the plasticizer described low temperature resistant, low conductivity thermal seal material, characterized in that the plasticizer is an ester of adipic acid and a polyol polymerized, trioctyl trimellitate, dioctyl terephthalate, dioctyl sebum, cyclohexane 1,2-diisononyl dicarboxylate, dioctyl adipate and epoxy soybean oil in one or more; Furthermore, the polyolefin compound is any one of EVA, POE, PE, and LDPE, and the expanded microspheres are organic expanded microspheres containing silicone-modified acrylic resin; Furthermore, the VA content in the EVA is 25-35%; Furthermore, the particle size of the expanded microspheres is 1-50 μm; Furthermore, the first lubricant and the second lubricant are independently selected from one or more of stearic acid, paraffin wax and PE wax; Furthermore, the dispersing compatibilizer is ethylene bis stearamide; Furthermore, the antioxidant is at least one of 1010 antioxidant or 1072 antioxidant.

[0007] Furthermore, the stabilizer is selected from one or more of zinc stearate, calcium stearate, hydrotalcite, pentaerythritol, phosphite, β-diketone and 1010 antioxidant; Furthermore, the antibacterial and antifungal agent is one or two of DCOIT, ZPT and OIT; Further, the elastomer is at least one of TPU, TPEE and SEBS; Further, the weight ratio of the modified PVC base material and the expansion masterbatch is 100: (0.1-3); The present invention provides a method for preparing a low-temperature resistant and low-conductivity thermal sealing material, comprising the following steps: S1. Mixing PVC, a first lubricant, a stabilizer, and an antibacterial and mildew-proof agent according to the formula amount to obtain a mixture A; S2. Mixing the mixture A with the plasticizer and GMA-SEBS-EVA in order according to the formula amount to obtain a mixture B, and mixing the obtained mixture B with an elastomer to obtain a mixture C; S3, the mixture C is mixed at a temperature of 95-140 ℃, conveyed to a single-screw extruder, and extruded at 100-140 ℃ to obtain a modified PVC base material; S4, mixing the polyolefin compound, the second lubricant and the antioxidant, mixing them evenly and then blending them with the expanded microspheres and the dispersing compatibilizer to obtain a mixture D; S5. Put the mixture D into a banbury mixer for banburying at a temperature of 70-90° C. for 5-10 min to obtain a mixture E; S6, the mixture E is conveyed to a single-screw extruder for extrusion molding, wherein the temperature of the single screw zone 1 is 50-70 ° C, the temperature of the second zone is 70-90 ° C, the temperature of the third zone is 70-90 ° C, the temperature of the fourth zone is 70-90 ° C, and the head temperature is 80-100 ° C to obtain an expanded masterbatch; S7. Mix the modified PVC base material and the expansion masterbatch, and extrude at 140-160° C. to obtain a low-temperature resistant and low-conductivity thermal sealing material.

[0008] The present invention also provides an application of a low-temperature resistant, low-heat-conductivity thermal sealing material in a door seal of a refrigeration appliance.

[0009] Beneficial effects of the present invention: 1. The present invention introduces the compatibilizer GMA-SEBS-EVA. The epoxy groups in its amphiphilic structure can form a strong interfacial bond with PVC / polyolefin compounds, greatly improving the interfacial bonding ability compared to traditional systems. This effectively solves the problem of poor compatibility of the PVC / SEBS / polyolefin compound multiphase system. The prepared door seal has improved tensile strength and elongation at break.

[0010] 2. The present invention adds elastomers such as SEBS and a compatibilizer GMA-SEBS-EVA to the low-temperature-resistant, low-conductivity heat-sealing material. Since elastomers such as SEBS have excellent elasticity, flexibility, and low-temperature resistance, and the compatibilizer GMA-SEBS-EVA improves compatibility and enhances interfacial bonding, the toughening effect of the elastomer is fully utilized. The synergistic effect of the two enables the prepared low-temperature-resistant, low-conductivity heat-sealing material to maintain excellent flexibility at -40°C, and its low-temperature impact strength is greatly improved compared to conventional systems.

[0011] 3. The present invention introduces the compatibilizer GMA-SEBS-EVA. Due to its amphiphilic structure, it can induce the matrix elastomers such as PVC / SEBS to form a uniformly dispersed "sea island" phase. Combined with the fact that the organic expanded microspheres in the expanded microspheres can be evenly dispersed under the action of the compatibilizer, it has the advantages of stable microsphere size and low breakage rate. As a result, the prepared low-temperature resistant and low-heat conductive seal has the advantages of few defects and smooth surface.

[0012] 4. The present invention can adjust the size of the organic expandable microspheres by adjusting the addition amounts of the organic expandable microspheres and the polyolefin compound, achieving controllable micro-crosslinking and foaming of the system. This is because the elastomer such as SEBS / the compatibilizer GMA-SEBS-EVA / the matrix PVC form a "grid-coated island-in-the-sea structure." The presence of numerous phase interfaces within this structure effectively inhibits the expansion rate of the organic expandable microspheres. Therefore, by precisely adjusting the ratio of the organic expandable microspheres to the polyolefin compound, controllable micro-crosslinking and foaming of the system can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a microscope image of the side of the door sealing material of Example 1.

[0014] Figure 2 This is a microscope image of the side of the door sealing material of Example 2.

[0015] Figure 3 This is a microscope image of the side of the door sealing material of Example 3.

[0016] Figure 4 This is a schematic diagram of the appearance of the door sealing material of Example 1. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0018] The experimental methods in the following examples, unless otherwise specified, are conventional methods and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources. For example, the types and sources of the raw materials involved in the preparation examples, examples, and comparative examples are shown in Table 1, which is as follows: Table 1

[0019] Preparation Example 1

[0020] Preparation of GMA-SEBS-EVA: S1, weighed 44g of di-tert-butyl peroxide, 16g of solid paraffin, 22g of antioxidant 1035, 4kg SEBS and 0.4kgGMA; SEBS and di-tert-butyl peroxide were added to ethylbenzene, heated to 85 ° C, stirred and mixed for 10min, GMA, solid paraffin and antioxidant 1035 were added, stirring and mixing was continued for 15min, heated to 120 ° C for 6h to obtain a mixture A; S2, weighed 26g of di-tert-butyl peroxide, 8g of solid paraffin, 14kg parts by mass of antioxidant 1035 and 0.24kg of EVA; the mixture A and di-tert-butyl peroxide was heated to 90 ° C, stirred and mixed for 8min, EVA, solid paraffin and antioxidant 1035 were added, and stirring and mixing was continued for 18min, and heated to 140 ° C for 5h to obtain a mixture B; S3. Add mixture B into a twin-screw extruder, perform melt blending and extrusion at a temperature interval of 90-140° C. and a die head temperature of 140° C., and granulate through a water stranding machine and a cutting machine to finally obtain GMA-SEBS-EVA.

[0021] Preparation Example 2

[0022] S1, weighed 27g di-tert-butyl peroxide, 6.7g solid paraffin, 11g antioxidant 1035, 4kg SEBS and 0.4kgGMA; SEBS and di-tert-butyl peroxide were added to xylene, heated to 70 ° C, stirred and mixed for 8min, GMA, solid paraffin and antioxidant 1035 were added, stirring and mixing was continued for 10min, heated to 80 ° C for 3h to obtain a mixture A;

[0023] S2, weighed 17.8g of di-tert-butyl peroxide, 2.2g of solid paraffin, 6.67g of antioxidant 1035 and 0.18kg of EVA; the mixture A and di-tert-butyl peroxide was heated to 75 ° C, stirred and mixed for 6 minutes, EVA, solid paraffin and antioxidant 1035 were added, and the stirring was continued for 12 minutes, and the mixture was heated to 90 ° C for 2 hours to obtain a mixture B;

[0024] S3. Add mixture B into a twin-screw extruder, perform melt blending and extrusion at a temperature interval of 90-140° C. and a die head temperature of 140° C., and granulate through a water stranding machine and a cutting machine to finally obtain GMA-SEBS-EVA.

[0025] Comparative Preparation Example 1

[0026] Preparation of GMA-SEBS-TPU: Compared with Preparation Example 1, the only difference is that EVA is replaced by TPU of equal mass, and the other steps and conditions remain the same; finally, GMA-SEBS-TPU is prepared.

[0027] Comparative Preparation Example 2

[0028] S1, weighed 44g of di-tert-butyl peroxide, 16g of solid paraffin and 22g of antioxidant 1035, 4kg SEBS and 0.4kgGMA; SEBS and di-tert-butyl peroxide were added to the solvent, heated to 85 ° C, stirred and mixed for 10min, GMA, solid paraffin and antioxidant 1035 were added, stirring and mixing was continued for 15min, heated to 120 ° C for 6h to obtain a mixture A;

[0029] S2. Add mixture A into a twin-screw extruder, perform melt blending and extrusion at a temperature interval of 90-140° C. and a die head temperature of 140° C., and granulate through a water stranding machine and a cutting machine to finally obtain SEBS-g-GMA.

[0030] Example 1

[0031] S1. Add 3 kg of PVC, 15 g of paraffin wax, 0.12 kg of zinc stearate, and 9 g of DCOIT into a high-speed mixing pot and mix for 3 min to obtain a mixture A. S2. 1.98 kg of trioctyl trimellitate was added to a plasticizer storage cylinder, and the mixture was slowly added to mixture A after the temperature was raised to 50° C. When the temperature of the high-speed mixing pot reached 100° C., all the trioctyl trimellitate was added to mixture A to obtain mixture B; then, when the temperature of the high-speed mixing pot was raised to 115° C., GMA-SEBS-EVA was added to mixture B; the temperature was continued to be raised, and when the temperature of the high-speed mixing pot reached 125° C., the obtained mixture was mixed with SEBS powder butyronitrile, and mixed for 3 min to obtain mixture C; S3, mixing the mixture C in an internal mixer at a temperature of 130° C., conveying the mixture to a single-screw extruder after mixing, and extruding the mixture at 125° C. to obtain a modified PVC base material; S4, 1 kg of EVA, 2 g of antioxidant 1010, and 5 g of stearic acid were placed in a high-speed mixing pot and mixed for 3 min. The resulting mixture was then blended with 1 kg of organic expandable microspheres and 10 g of ethylene bisstearamide to obtain a mixture D; S5. Mixture D was put into an internal mixer for internal mixing at a temperature of 75° C. for 6 min to obtain mixture E. S6. The mixed material E is conveyed to a single-screw extruder for extrusion molding, wherein the temperature of the single-screw zone 1 is 60°C, the temperature of the second zone is 80°C, the temperature of the third zone is 80°C, the temperature of the fourth zone is 85°C, and the head temperature is 90°C to obtain an expanded masterbatch; S7. Mix 4 kg of modified PVC base material and 40 g of expansion masterbatch, and then foam and extrude at 140° C. to obtain a low-temperature resistant and low-conductivity thermal sealing material.

[0032] Example 2

[0033] S1. Add 3 kg of PVC, 15 g of paraffin wax, 0.12 kg of zinc stearate, and 9 g of DCOIT into a high-speed mixing pot and mix for 3 min to obtain a mixture A. S2. 1.98 kg of trioctyl trimellitate was added to a plasticizer storage cylinder, and the mixture was slowly added to mixture A after the temperature was raised to 50° C. When the temperature of the high-speed mixing pot reached 100° C., all the trioctyl trimellitate was added to mixture A to obtain mixture B; then, when the temperature of the high-speed mixing pot was raised to 115° C., GMA-SEBS-EVA was added to mixture B; the temperature was continued to be raised, and when the temperature of the high-speed mixing pot reached 125° C., the obtained mixture was mixed with TPU powder butyronitrile, and mixed for 3 min to obtain mixture C; S3, mixing the mixture C in an internal mixer at a temperature of 130° C., conveying the mixture to a single-screw extruder after mixing, and extruding the mixture at 125° C. to obtain a modified PVC base material; S4. 1 kg of EVA, 2 g of antioxidant 1010, and 5 g of stearic acid were placed in a high-speed mixing pot and mixed for 3 min. The resulting mixture was then blended with 1.2 kg of organic expandable microspheres and 10 g of ethylene bisstearamide to obtain a mixture D. S5. Mixture D was put into an internal mixer for internal mixing at a temperature of 75° C. for 6 min to obtain mixture E. S6. The mixed material E is conveyed to a single-screw extruder for extrusion molding, wherein the temperature of the single-screw zone 1 is 60°C, the temperature of the second zone is 80°C, the temperature of the third zone is 80°C, the temperature of the fourth zone is 85°C, and the head temperature is 90°C to obtain an expanded masterbatch; S7. Mix 4 kg of modified PVC base material and 40 g of expansion masterbatch, and then foam and extrude at 140° C. to obtain a low-temperature resistant and low-conductivity thermal sealing material.

[0034] Example 3

[0035] S1. Add 3 kg of PVC, 15 g of paraffin wax, 0.12 kg of zinc stearate, and 9 g of DCOIT into a high-speed mixing pot and mix for 3 min to obtain a mixture A. S2. 1.98 kg of trioctyl trimellitate was added to a plasticizer storage cylinder, and the mixture was slowly added to mixture A after the temperature was raised to 50° C. When the temperature of the high-speed mixing pot reached 100° C., all the trioctyl trimellitate was added to mixture A to obtain mixture B; then, when the temperature of the high-speed mixing pot was raised to 115° C., GMA-SEBS-EVA was added to mixture B; the temperature was continued to be raised, and when the temperature of the high-speed mixing pot reached 125° C., the obtained mixture was mixed with TPEE powder butyronitrile, and mixed for 3 minutes to obtain mixture C; S3, mixing the mixture C in an internal mixer at a temperature of 130° C., conveying the mixture to a single-screw extruder after mixing, and extruding the mixture at 125° C. to obtain a modified PVC base material; S4, 1 kg of EVA, 2 g of antioxidant 1010 and 5 g of stearic acid were placed in a high-speed mixing pot and mixed for 3 min. The resulting mixture was then blended with 0.4 kg of organic expandable microspheres and 10 g of ethylene bisstearamide to obtain a mixture D; S5. Mixture D was put into an internal mixer for internal mixing at a temperature of 75° C. for 6 min to obtain mixture E. S6. The mixed material E is conveyed to a single-screw extruder for extrusion molding, wherein the temperature of the single-screw zone 1 is 60°C, the temperature of the second zone is 80°C, the temperature of the third zone is 80°C, the temperature of the fourth zone is 85°C, and the head temperature is 90°C to obtain an expanded masterbatch; S7. Mix 4 kg of modified PVC base material and 40 g of expansion masterbatch, and then foam and extrude at 140° C. to obtain a low-temperature resistant and low-conductivity thermal sealing material.

[0036] Comparative Example 1

[0037] The preparation method was followed as in Example 1, except that the compatibilizer GMA-SEBS-EVA was replaced with an equal weight of SEBS grafted with maleic anhydride (SEBS-g-MAH).

[0038] Comparative Example 2

[0039] The preparation was carried out according to the method of Example 1, except that the compatibilizer GMA-SEBS-EVA was replaced with an equal weight of GMA-SEBS-TPU prepared in Comparative Preparation Example 1.

[0040] Comparative Example 3

[0041] The preparation was carried out according to the method of Example 1, except that the compatibilizer GMA-SEBS-EVA was replaced with an equal weight of SEBS-g-GMA prepared in Comparative Preparation Example 2.

[0042] Comparative Example 4

[0043] The preparation was carried out according to the method of Example 1, except that the compatibilizer GMA-SEBS-EVA was replaced with an equal weight of EVA-g-GMA.

[0044] Comparative Example 5

[0045] The method of Example 1 was used for preparation, except that the content of the expanded microspheres was 30 parts by weight (less than the preferred ratio) relative to 100 parts by weight of EVA.

[0046] Comparative Example 6

[0047] The method of Example 1 was used for preparation, except that the content of the expanded microspheres was 130 parts by weight (greater than the preferred ratio) relative to 100 parts by weight of EVA.

[0048] In order to more intuitively and clearly demonstrate the differences between the embodiments of the present invention and the comparative examples in various key performance indicators, and to facilitate understanding of the significant advantages brought about by the technical solution of the present invention, the formulas of the key materials of Examples 1-3 and Comparative Examples 1-6 are listed in Table 2.

[0049] Table 2

[0050] Test Case

[0051] Elongation at break: tested according to the method of GB / T 1040.1-2006. The results are shown in Table 3. Tensile strength: tested according to the method of GB / T 1040.3-2006. The results are shown in Table 3. HIPS board migration: Place the test piece in a desiccator for 24 hours and weigh it, record it as M1. Then sandwich it between two standard HIPS boards to form a test sample. Place the test sample horizontally in the oven and then apply a 1.1kg weight or iron block (equivalent to 0.22kg / cm 2 The test piece was placed in an oven at 70°C ± 2°C for 72 hours, and then taken out and separated from the standard plate. The test piece was placed in a desiccator and cooled to room temperature, which was recorded as M2. The mass loss rate was calculated using the formula (M1-M2) / M1×100%. The results are shown in Table 3. PCM board adhesion: stick a 100mm long door seal rubber sample (including magnetic strip) (50mm×10mm×2mm) on the board and apply 0.2kg / cm 2 The load was placed in a constant temperature and humidity chamber at 40±3℃ and humidity above 93% for 168 hours, then taken out and placed at room temperature for at least 30 minutes before conducting a tensile test. The results are shown in Table 3. Thermal conductivity: tested in accordance with GB / T 11205-2009, using the hot wire method for measuring thermal conductivity of rubber in the standard. The results are shown in Table 3. Low temperature brittle temperature: The test was conducted according to the method for testing the low temperature brittle temperature of rubber in the standard GB / T 15256-2014. The results are shown in Table 3. Table 3

[0052] As can be seen from Table 3, in terms of tensile strength, elongation at break, PCM board adhesion, HIPS board migration, and low-temperature brittle temperature performance, Examples 1-3 all have tensile strengths exceeding 11.8 MPa, elongations at break exceeding 336%, PCM board adhesion below 6 N, HIPS board migration below 1.23%, and low-temperature brittle temperatures of -40°C. In contrast, Comparative Examples 1-4 have poor compatibility with the PVC / SEBS / EVA system due to the lack of amphiphilicity of SEBS-g-MAH, GMA-SEBS-TPU, SEBS-g-GMA, and EVA-g-GMA. Consequently, their tensile strengths are all below 9.2 MPa, their elongations at break are all below 232%, their PCM board adhesion is all above 29 N, their HIPS board migration is all above 1.28%, and their low-temperature brittle temperatures are all -30°C. Further observation of Comparative Examples 5 and 6 shows that when the expanded microspheres are added in excess, the mechanical properties of the product decrease significantly. This is mainly because the excessive organic expanded microspheres increase the microsphere breakage rate, resulting in product defects. When the expanded microspheres are added inadequately, the thermal conductivity of the product increases, and the expected low thermal conductivity effect cannot be achieved. At the same time, the low-temperature brittle temperature also increases due to improper addition of expanded microspheres. Figure 1-3 It can be seen that by adjusting the addition ratio of organic expanded microspheres and EVA, the size of organic expanded microspheres and the degree of cross-linking of the system can be effectively controlled. Figure 1-3 We can see that the low-temperature resistant and low-conductivity thermal sealing material prepared by the present invention has uniform distribution of organic expanded microspheres, stable size, low breakage rate, dense foamed particles and a smooth surface without defects.

[0053] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A low temperature resistant and low conductivity heat sealing material, characterized in that: Contains modified PVC base material and expansion masterbatch; The modified PVC base material comprises PVC, a plasticizer, an elastomer, a stabilizer, a first lubricant, an antibacterial and mildew-proof agent, and GMA-SEBS-EVA; The expanding masterbatch comprises a polyolefin compound, expanding microspheres, an antioxidant, a dispersing compatibilizer and a second lubricant; The GMA-SEBS-EVA comprises the following raw materials in parts by weight: 180-200 parts of SEBS, 8-12 parts of EVA, 18-20 parts of GMA, 2-3.5 parts of initiator, 0.4-1.2 parts of lubricant, and 0.8-1.8 parts of antioxidant.

2. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: In the modified PVC base material, relative to 100 parts by weight of PVC, the plasticizer is 50-90 parts, the elastomer is 5-20 parts, the stabilizer is 1-5 parts, the first lubricant is 0.2-1 parts, the antibacterial and mildewproof agent is 0.2-2 parts, and the GMA-SEBS-EVA is 0.1-0.5 parts.

3. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: In the expanding masterbatch, relative to 100 parts by weight of the polyolefin compound, the expanding microspheres are 40-120 parts, the antioxidant is 0.2-1 part, the second lubricant is 0.2-1 part, and the dispersing compatibilizer is 0.2-1 part.

4. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: The plasticizer is one or more of the following: ester polymerized from adipic acid and polyol, trioctyl trimellitate, dioctyl terephthalate, dioctyl sebacate, diisononyl cyclohexane 1,2-dicarboxylate, dioctyl adipate and epoxidized soybean oil.

5. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: The polyolefin compound is any one of EVA, POE, PE and LDPE; and the expanded microspheres are organic expanded microspheres containing silicone-modified acrylic resin.

6. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: The first lubricant and the second lubricant are one or more of stearic acid, paraffin and PE wax; the dispersing compatibilizer is ethylene bis stearamide; and the antioxidant is at least one of 1010 antioxidant and 1072 antioxidant.

7. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: The stabilizer is one or more of zinc stearate, calcium stearate, hydrotalcite, pentaerythritol, phosphite, β-diketone and 1010 antioxidant; the antibacterial and mildew-proof agent is one or two of DCOIT, ZPT and OIT; and the elastomer is at least one of TPU, TPEE and SEBS.

8. The low temperature resistant and low conductive heat sealing material according to claim 1, characterized in that: The weight ratio of the modified PVC base material to the expansion masterbatch is 100:(0.1-3).

9. A method for preparing the low-temperature resistant, low-conductivity thermal sealing material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: S1. Mixing PVC, a first lubricant, a stabilizer, and an antibacterial and mildew-proof agent according to the formula amount to obtain a mixture A; S2. Mixing the mixture A with the plasticizer and GMA-SEBS-EVA in order according to the formula amount to obtain a mixture B, and mixing the obtained mixture B with an elastomer to obtain a mixture C; S3, the mixture C is mixed at a temperature of 95-140 ℃, conveyed to a single-screw extruder, and extruded at 100-140 ℃ to obtain a modified PVC base material; S4, mixing the polyolefin compound, the second lubricant and the antioxidant, mixing them evenly and then blending them with the expanded microspheres and the dispersing compatibilizer to obtain a mixture D; S5. Put the mixture D into a banbury mixer for banburying at a temperature of 70-90° C. for 5-10 min to obtain a mixture E; S6, the mixture E is conveyed to a single-screw extruder for extrusion molding, wherein the temperature of the single screw zone 1 is 50-70 ° C, the temperature of the second zone is 70-90 ° C, the temperature of the third zone is 70-90 ° C, the temperature of the fourth zone is 70-90 ° C, and the head temperature is 80-100 ° C to obtain an expanded masterbatch; S7. Mix the modified PVC base material and the expansion masterbatch, and extrude at 140-160° C. to obtain a low-temperature resistant and low-conductivity thermal sealing material.

10. A door seal, characterized in that: Prepared from the material according to any one of claims 1 to 8.

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