A microcellular foamed door gasket material and method of making same

Abstract

The application provides a kind of microcellular foamed heat insulation door seal material and its preparation method, it relates to plastic material technical field.The microcellular foamed heat insulation door seal of the application is obtained by PVC granules and TPU foaming master batch together extrusion molding.The synergistic effect between raw materials is utilized in the application, the heat insulation, toughness, low temperature resistance, aging resistance and resilience of the material are improved, the power consumption of refrigerator is reduced, and the energy saving effect is remarkable.Furthermore, the application also provides a high heat insulation door seal structure part prepared by the material, the sealing and heat insulation performance of the door seal is improved, and has the advantages of smooth opening and closing, avoiding cold leakage, good condensation prevention effect and the like.

Description

Technical Field

[0001] This invention relates to the field of plastic materials technology, and in particular to a microporous foamed insulation and sealing material and its preparation method. Background Technology

[0002] To improve the sealing and heat insulation performance of door seals and reduce refrigerator power consumption to meet higher energy efficiency requirements, current methods typically involve adjusting the structural characteristics of door seals and improving or upgrading raw material formulas.

[0003] Existing foamed door seals typically have a cell diameter greater than 50mm and a cell density less than 10⁶ cells / cm³. Due to their large cell diameter, these large cells are easily damaged under stress, becoming the source of material cracks and reducing the material's mechanical properties. Furthermore, frequent opening and closing accelerates the aging of the door seal, leading to breakage. Meanwhile, existing refrigerator door seal components mainly meet energy-saving requirements by incorporating airbag structures in their design. However, airbag-type refrigerator door seal components are prone to problems such as difficult opening and closing, condensation, and poor sealing.

[0004] Therefore, how to improve the refrigerator door seal in terms of both raw materials and structure to enhance its sealing and heat insulation performance, reduce the refrigerator's power consumption, and meet requirements such as smooth opening and closing, preventing cold leakage, and good anti-condensation effect is one of the technical problems that urgently need to be solved. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a microporous foamed door seal material. By modifying PVC raw materials and using a specific foaming agent, the invention solves the problems of poor pressure resistance and easy breakage of foamed door seals, and significantly improves the material's thermal insulation, toughness, and strength.

[0006] The microporous foamed insulation and sealing material of this invention comprises the following raw materials in parts by weight:

[0007] 80-90 parts PVC granules, 10-20 parts TPU foaming masterbatch.

[0008] Further, the PVC granules comprise the following raw materials in parts by weight: 100 parts PVC resin powder, 50-70 parts plasticizer, 20-35 parts filler, 0.2-0.5 parts lubricant, 2-5 parts heat stabilizer, 0.1-1.2 parts auxiliary stabilizer, 0.5-2 parts antibacterial and antifungal agent, 0.2-2 parts crosslinking agent, and 0.9-1.8 parts initiator; wherein the crosslinking agent is trimethylolpropane trimethacrylate.

[0009] Furthermore, the TPU foaming masterbatch comprises the following raw materials in parts by weight: 60-80 parts TPU, 20-40 parts foaming agent, 1-5 parts filler, and 0.1-0.5 parts lubricant.

[0010] Furthermore, the TPU is a low-melting-point polyester polyurethane with a melting point of 90℃-120℃ and a hardness of 60-70A.

[0011] Furthermore, the foaming agent is an acrylic foaming agent, and the foaming temperature is 140℃-180℃.

[0012] Furthermore, the acrylic foaming agent is Expansion microspheres.

[0013] The antibacterial and antifungal agent is zinc phosphate or nano zinc.

[0014] Furthermore, the plasticizer is one or more of epoxidized soybean oil, DOA, DOTP, and TOTM plasticizer.

[0015] Furthermore, the filler is one or more of hollow glass microspheres, calcium carbonate, and barium sulfate.

[0016] Furthermore, the initiator is azobisisobutyronitrile.

[0017] Furthermore, the lubricant is one or two of Fischer-Tropsch wax, oxidized polyethylene wax, and oleamide.

[0018] Furthermore, the heat stabilizer is one or both of dibutyltin dilaurate and dibutyltin maleate.

[0019] Furthermore, the auxiliary stabilizer is hydrotalcite.

[0020] The method for preparing the PVC granules includes the following steps:

[0021] First, add PVC resin powder and antibacterial and antifungal agent, adjust the speed to 100-200 r / min, add 2 / 3 of the plasticizer, and then adjust the speed to 500 r / min and stir. When the temperature reaches 90℃, first add foaming agent, filler, heat stabilizer, auxiliary stabilizer and lubricant, and add the remaining plasticizer at the same time. When the temperature reaches 105℃, add filler, stir to 130℃, add crosslinking agent and initiator to carry out crosslinking reaction for 10-120 min. After the reaction is completed, cool and stir to 70℃ and enter the twin-screw extruder for granulation.

[0022] The preparation method of the TPU foaming masterbatch includes the following steps:

[0023] Weigh out TPU, foaming agent, filler and lubricant according to the weight ratio, stir in a high-speed mixer of 400-600r / min for 15-30min, heat to 90℃-120℃, and then extrude and granulate through a twin-screw extruder to obtain TPU foaming masterbatch.

[0024] This invention utilizes the synergistic effect of trimethylolpropane trimethacrylate and acrylic foaming agents to improve the toughness and anti-aging properties of materials without adding anti-aging agents.

[0025] The present invention also provides a method for preparing the microporous foamed insulation door sealing material, specifically including the following steps:

[0026] Weigh out PVC granules and TPU foaming masterbatch according to the weight ratio. Add the PVC granules through the main feed port of the extruder and add the above-mentioned weight proportions of TPU foaming masterbatch through the side feed port. The product is obtained after single-screw extrusion.

[0027] Furthermore, the extrusion temperature is 120℃-150℃.

[0028] Furthermore, the extruded microporous foamed door sealing material is cut to a predetermined size and then left to stand for 6-12 hours to produce a finished door seal sleeve. A magnetic strip is inserted into the finished door seal sleeve, and after corner cutting and welding, the door seal is formed.

[0029] Adding TPU foaming masterbatch after the initial stage of the preparation process avoids mixing with PVC and then granulating again using a twin-screw extruder. Using a single-screw extruder for extrusion molding can reduce the breakage rate of air bubbles.

[0030] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0031] This invention improves the thermal insulation, toughness, low-temperature resistance, aging resistance, and resilience of PVC by crosslinking modification and combining the synergistic effect of crosslinking agents and foaming agents, thereby reducing refrigerator power consumption and achieving significant energy-saving effects. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of the insulated door sealing structure of the present invention.

[0034] Explanation of reference numerals in the attached drawings: 1. Refrigerator body; 2. Door seal structure; 3. Refrigerator door; 4. Magnetic strip; 5. Telescopic deformation rib; 6. Main airbag; 7. Cover sealing wing; 8. Installed cabin airbag; 9. Cabin sealing wing; 10. Cabin anti-slip rib; 11. Middle thickened crossbeam; 12. Small connecting part; 13. U-shaped connecting rib part; 14. First sealing short wing; 15. Second sealing short wing; 16. C-shaped sealing edge; 17. Secondary airbag; 18. Magnetic strip airbag. Detailed Implementation

[0035] The technical solution provided by the present invention will be further described below with reference to the embodiments.

[0036] Example 1

[0037] A microporous foamed insulation and sealing material is composed of 85 parts of PVC particles and 15 parts of TPU foaming masterbatch.

[0038] The PVC granules are composed of the following raw materials in parts by weight: 100 parts PVC resin powder, 55 parts TOTM plasticizer, 35 parts calcium carbonate, 0.2 parts Fischer-Tropsch wax, 2 parts dibutyltin dilaurate, 0.1 parts hydrotalcite, 1.5 parts nano zinc, 1.5 parts trimethylolpropane trimethacrylate, and 1.0 part azobisisobutyronitrile.

[0039] The TPU foaming masterbatch comprises the following raw materials in parts by weight: 80 parts TPU, 40 parts foaming agent, 5 parts hollow glass microspheres, and 0.3 parts oxidized polyethylene wax; the TPU is a low-melting-point polyester polyurethane with a melting point of 120°C and a hardness of 70A; the foaming agent is Expansion microsphere foaming agent, model 920DU40, purchased from Nourion Chemicals (Guangzhou) Co., Ltd.

[0040] The steps for preparing the PVC granules are as follows:

[0041] First, add PVC resin powder and antibacterial and antifungal agent, adjust the speed to 200 r / min and add 2 / 3 of the plasticizer. After adding the plasticizer, adjust the speed to 500 r / min and stir. When the temperature reaches 90℃, first add foaming agent, filler, heat stabilizer, auxiliary stabilizer and lubricant, and add the remaining plasticizer at the same time. When the temperature reaches 105℃, add filler and stir to 130℃. Then add crosslinking agent and initiator to carry out crosslinking reaction for 90 min. After the reaction is completed, cool and stir to 70℃ and enter the twin-screw extruder for granulation.

[0042] The preparation method of the TPU foaming masterbatch is as follows:

[0043] Weigh out TPU, foaming agent, filler and lubricant according to the weight ratio, stir in a high-speed mixer at 600r / min for 30min, heat to 120℃, and then extrude and granulate through a twin-screw extruder to obtain TPU foaming masterbatch.

[0044] The preparation method of the microporous foamed insulation door sealing material is as follows:

[0045] Weigh out PVC granules and TPU foaming masterbatch according to the weight ratio. Add the PVC granules through the main feed port of the extruder and add the above-mentioned weight proportions of TPU foaming masterbatch through the side feed port. Extrude at 150°C to obtain the final product.

[0046] Example 2

[0047] Same as Example 1, except that: the microporous foamed insulation door sealing material is composed of 80 parts of PVC particles and 20 parts of TPU foaming masterbatch;

[0048] The PVC granules are composed of the following raw materials in parts by weight: 100 parts PVC resin powder, 70 parts DOA plasticizer, 25 parts hollow glass microspheres, 0.5 parts oleamide, 3 parts dibutyltin maleate, 0.6 parts hydrotalcite, 0.5 parts zinc phosphate, 1.0 part trimethylolpropane trimethacrylate, and 1.0 part azobisisobutyronitrile.

[0049] The TPU foaming masterbatch comprises the following raw materials in parts by weight: 60 parts TPU, 35 parts foaming agent, 3 parts barium sulfate, and 0.35 parts oxidized polyethylene wax; the TPU is a low-melting-point polyester polyurethane with a melting point of 120°C and a hardness of 70A; the foaming agent is Expansion microsphere foaming agent, model 920DU40, purchased from Nourion Chemicals (Guangzhou) Co., Ltd.

[0050] Example 3

[0051] Same as Example 1, except that: the microporous foamed insulation door sealing material is composed of 90 parts of PVC particles and 10 parts of TPU foaming masterbatch;

[0052] The PVC granules are composed of the following raw materials in parts by weight: 100 parts PVC resin powder, 55 parts epoxidized soybean oil, 20 parts hollow glass microspheres, 0.25 parts Fischer-Tropsch wax, 2.5 parts dibutyltin maleate, 1.2 parts hydrotalcite, 1.5 parts zinc phosphate, 2 parts trimethylolpropane trimethacrylate, and 1.1 parts azobisisobutyronitrile.

[0053] The TPU foaming masterbatch comprises the following raw materials in parts by weight: 75 parts TPU, 30 parts foaming agent, 2 parts barium sulfate, and 0.3 parts oxyoleamide; the TPU is a low-melting-point polyester polyurethane with a melting point of 120°C and a hardness of 70A; the foaming agent is Expansion microsphere foaming agent, model 920DU40, purchased from Nourion Chemicals (Guangzhou) Co., Ltd.

[0054] Comparative Example 1

[0055] Same as Example 1, except that no crosslinking agent and initiator were added.

[0056] Comparative Example 2

[0057] Same as Example 1, except that the foaming agent is replaced with an equal amount of AC foaming agent.

[0058] Example 3

[0059] Same as Example 1, except that trimethylolpropane trimethacrylate is replaced with an equal amount of dicumyl peroxide.

[0060] Test Example 1

[0061] The elongation at break and aging resistance of the products prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0062] The aging resistance test method is as follows: After the sample is placed under 40W ultraviolet light irradiation for 2500h, the elongation retention rate is tested.

[0063]

[0064]

[0065] like Figure 1 As shown, a door seal structure using the microporous foamed insulation door seal material described in this application includes a refrigerator body 1, a door seal structure 2, and a refrigerator door 3.

[0066] The door seal component 2 is disposed on the contact surface between the refrigerator door 3 and the refrigerator body 1.

[0067] The door seal structure 2 is made of the microporous foamed insulating door seal material described in this application. The door seal structure 2 includes a main airbag 6, a secondary airbag 17 and a magnetic strip airbag 18, wherein the magnetic strip airbag 18 is provided with a magnetic strip 4 for attracting the refrigerator body 1.

[0068] The auxiliary airbag 17 is located at the right end of the magnetic strip airbag 18, and the main airbag 6 is located at the lower end of the magnetic strip airbag 18 and the auxiliary airbag 17.

[0069] The main airbag 6 includes a thickened crossbeam 11, a telescopic deformation rib 5, and a U-shaped connecting rib 13. The upper left end of the thickened crossbeam 11 is connected to the lower wall of the magnetic strip airbag 18 via the telescopic deformation rib 5, and the upper right end of the thickened crossbeam 11 is connected to the lower wall of the auxiliary airbag 17 via the U-shaped connecting rib 13. The lower left end of the thickened crossbeam 11 engages with the refrigerator door 3 via a sealing fin 7, and the lower right end of the thickened crossbeam 11 engages with the refrigerator door 3 via a small connecting part 12. This prevents excessive stretching and warping, which could lead to cold leakage.

[0070] The lower end of the thickened crossbeam 11 is provided with a small mounting airbag 8. Small mounting airbag 8 has anti-slip ribs 10 on its left and right sides. The two upward-sloping anti-slip ribs 10 allow the left and right sides of the small mounting airbag 8 to form two relatively sealed chambers with the inner side of the recessed groove of the refrigerator door 3, further improving the sealing performance between the refrigerator body 1 and the refrigerator door 3 and preventing condensation when opening and closing the refrigerator door 3. The bottom end of the small mounting airbag 8 is provided with small mounting sealing wings 9 to reduce installation resistance. The refrigerator door 3 has grooves that engage with the small mounting airbag 8, ensuring good connection stability.

[0071] The U-shaped connecting rib 13 is provided with a first sealing short wing 14 that cooperates with the refrigerator door 3. The U-shaped connecting rib 13, the first sealing short wing 14, the small connecting part 12, and the refrigerator door 3 form a third chamber. The third chamber can ensure good sealing between the lower part of the step of the refrigerator door 3 and the refrigerator body 1, and prevent cold leakage or condensation between the lower part of the step of the refrigerator door 3 and the refrigerator body 1.

[0072] The auxiliary airbag 17 is provided with a second sealing wing 15 on the right end to cooperate with the refrigerator door 3. The second sealing wing 15, the first sealing wing 14, the auxiliary airbag 17 and the refrigerator door 3 form a second chamber to prevent cold leakage or condensation between the middle part of the step of the refrigerator door 3 and the refrigerator body 1. This achieves a multi-seal effect, further enhances the sealing performance of the door seal, increases the temperature gradient distance between the inside and outside of the refrigerator, reduces the possibility of heat exchange, and thus achieves the purpose of reducing refrigerator energy consumption.

[0073] The upper right end of the auxiliary airbag 17 is provided with a C-shaped sealing edge 16 that cooperates with the refrigerator door 3. The deformable overlapping part, the auxiliary airbag 17, and the second sealing short wing 15 form a first chamber. The first chamber can enhance the overall resistance to compression and deformation, and can prevent cold leakage or condensation between the upper part of the step of the refrigerator door 3 and the refrigerator body 1.

[0074] The top edge of the magnetic stripe airbag 18, the top edge of the auxiliary airbag 17, and the variable overlapping part can form an upward-curving S-shaped sealing structure. The right side of the upward-curving S-shaped sealing structure can form a smooth overlapping air chamber between the refrigerator door 3 and the refrigerator body 1. The smooth overlapping air chamber allows the refrigerator door 3 to open and close smoothly and ensures a good seal between the refrigerator door 3 and the refrigerator body 1. The left side of the upward-curving S-shaped sealing structure can magnetically adhere to the refrigerator body 1, ensuring that the top surface of the entire door seal component 2 is tightly fitted to the refrigerator body 1, preventing cold leakage.

[0075] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A microcellular foam weather-stripping material, characterized by, The raw materials include the following weight parts: PVC particles 80-90 parts, TPU foaming master batch 10-20 parts; The PVC particles include the following weight parts of raw materials: PVC resin powder 100 parts, plasticizer 50-70 parts, filler 20-35 parts, lubricant 0.2-0.5 parts, heat stabilizer 2-5 parts, auxiliary stabilizer 0.1-1.2 parts, antibacterial and mildew-proof agent 0.5-2 parts, crosslinking agent 0.2-2 parts, initiator 0.9-1.8 parts; the crosslinking agent is trimethylolpropane trimethacrylate; The TPU foaming master batch includes the following weight parts of raw materials: TPU 60-80 parts, foaming agent 20-40 parts, filler 1-5 parts, lubricant 0.1-0.5 parts; The foaming agent is Expancel microspheres, and the foaming temperature is 140-180℃; The antibacterial and mildew-proof agent is zinc phosphate or nano-zinc.

2. The material of claim 1, wherein, The plasticizer is one or several of epoxy soybean oil, DOA, DOTP, TOTM plasticizer.

3. The material of claim 1, wherein, The filler is one or several of hollow glass microbeads, calcium carbonate, barium sulfate.

4. The material of claim 1, wherein, The initiator is azobisdimethyl isobutyronitrile.

5. The material of claim 1, wherein The lubricant is one or two of Fischer-Tropsch wax, oxidized polyethylene wax, oleic acid amide.

6. The material of claim 1, wherein The heat stabilizer is one or two of dibutyltin dilaurate and dibutyltin maleate.

7. The material of claim 1, wherein The auxiliary stabilizer is hydrotalcite.

8. The material of claim 1, wherein, The preparation method of the TPU foaming master batch includes the following steps: The TPU, foaming agent, filler and lubricant are weighed according to the weight ratio, stirred in a 400-600 r / min high-speed stirrer for 15-30 min, heated to 90-120℃, and then extruded and granulated by a double-screw extruder to obtain the TPU foaming master batch.

9. The method of making a microcellular foam gasket material of any of claims 1-8, characterized in that, The method includes the following steps: The PVC particles and TPU foaming master batch are weighed according to the weight ratio, the PVC particles are added from the main feeding port of the extruder, and the TPU foaming master batch in the above weight parts is added from the side feeding port, and the product is obtained after extrusion.

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