A foaming master batch, a preparation method and a low-temperature-resistant and low-thermal-conductivity PVC door seal material prepared by using the same

Abstract

The application provides a foaming master batch, a preparation method and a low-thermal-conductivity and low-temperature-resistant PVC door sealing material prepared from the same, and belongs to the technical field of door sealing materials. The raw materials of the foaming master batch are composed of organic expanded microspheres, EVA, SEBS, TBEC and TAIC. After the raw materials are uniformly mixed, the foaming master batch is obtained through closed-die kneading and underwater pelletizing. Then, the PVC base material and the foaming master batch are uniformly mixed and processed through single-screw extrusion to obtain the door sealing material. The synergistic components are innovatively designed to improve the low-thermal-conductivity and low-temperature-resistant performance of the door sealing material. Through the regulation of the closed pore structure, the thermal conductivity of the material can reach 0.14-0.16 W / (m*K). Through the improvement and enhancement of the crosslinking network, the tensile strength of the material can reach 12-13 MPa, and the elongation at break can reach 330-380%. Through the improvement of the SEBS component, the low-temperature-resistant performance of the material is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of door seal material technology, specifically relating to a foaming masterbatch, a preparation method, and a low-temperature resistant, low-thermal-conductivity PVC door seal material prepared using the masterbatch. Background Technology

[0002] The service conditions of refrigerator door seal materials are quite unique. They need to have low thermal conductivity to reduce heat exchange between the inside and outside of the refrigerator, while maintaining high elasticity at long-term low temperatures and resisting brittleness under repeated opening and closing pressure. However, current methods that rely on high inorganic fillers to reduce thermal conductivity inevitably block the heat conduction path, resulting in decreased mechanical strength and low-temperature brittleness. Therefore, in recent years, the development of low-temperature resistant, low-conductivity door seal materials has gradually become a new technological breakthrough point in the industry.

[0003] Furthermore, current refrigerator door seal materials have several drawbacks. For example, the use of AC foaming agent fails to form good closed-cell structures, resulting in an inability to effectively reduce thermal conductivity. The solid expanded microspheres used exhibit poor dispersion and low compatibility in the matrix, leading to insufficient interfacial bonding and consequently reduced mechanical properties. Even with TPU and SBR rubbers, which are compatible with PVC and designed for low-temperature resistance, the aging resistance, weather resistance, and low-temperature performance of the prepared door seal materials cannot be significantly improved.

[0004] Therefore, there is an urgent need to develop a low-temperature resistant, low-conductivity heat sealing material to meet the application requirements in low-temperature scenarios. Summary of the Invention

[0005] The purpose of this invention is to provide a foaming masterbatch, a preparation method, and a low-temperature resistant, low-thermal-conductivity PVC door seal material prepared using the masterbatch, so as to overcome the many problems existing in the door seal materials of the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A foaming masterbatch comprises the following components in parts by weight:

[0008] Solid foaming agent: organic expandable microspheres, 80-120 parts;

[0009] Foaming agent carrier: EVA or POE, 80~120 parts;

[0010] Synthetic rubber: SEBS, 20-40 parts;

[0011] Initiator: TBEC, 10-20 parts;

[0012] Crosslinking agent: TAIC, 12~40 parts.

[0013] As a further preferred embodiment of the present invention, the foaming masterbatch further includes the following components in parts by weight:

[0014] Lubricant: PE wax or stearic acid, 2-5 parts;

[0015] Compatibilizer: EVA-g-MAH, 6~10 parts.

[0016] Furthermore, the present invention also proposes a method for preparing the foaming masterbatch, which is as follows: first, the raw materials are mixed evenly, then the mixture is intensively kneaded at a temperature of 88~90℃ for 5~15 min, and finally the mixture is granulated underwater under cold water conditions to obtain the foaming masterbatch.

[0017] Furthermore, the present invention also proposes a low-temperature resistant, low-thermal-conductivity PVC door seal material, which is made of PVC base material and the above-mentioned foaming masterbatch, wherein the amount of foaming masterbatch added is 4% to 14% of the weight of PVC base material.

[0018] Furthermore, the present invention also proposes a method for preparing the low-temperature resistant and low-thermal-conductivity PVC door seal material, specifically: firstly, the PVC base material and foaming masterbatch are mixed evenly, and then processed by single-screw extrusion, with the extrusion temperature controlled at 140~160℃, thereby obtaining the low-temperature resistant and low-thermal-conductivity PVC door seal material.

[0019] Furthermore, the present invention also proposes a low-temperature resistant, low-thermal-conductivity PVC door seal prepared by the above method.

[0020] This invention proposes a foaming masterbatch and its preparation method, and also proposes a low-temperature resistant, low thermal conductivity PVC door sealing material and door seal strip prepared using this foaming masterbatch. Compared with the prior art, the beneficial effects of this invention are detailed as follows:

[0021] 1. The solid foaming agent used in this invention is expanded microspheres containing organosilicon-grafted acrylic acid. The initiator used is TBEC (2-ethylhexyl tert-butyl peroxide), with a half-life of 0.1 h (137°C). The crosslinking agent used is TAIC (1,3,5-triallyl-triazine-2,4,6(1H,3H,5H)-trione, also known as triallyl isocyanurate), which works in conjunction with the initiator to participate in crosslinking. EVA-g-MAH is added as a compatibilizer to improve the compatibility between EVA or POE and SEBS. In addition, this invention uses SEBS low-temperature resistant elastomer, which, compared with traditional TPU and SBR rubber, can achieve a comprehensive improvement in aging resistance, weather resistance, and low-temperature resistance.

[0022] 2. This invention features an innovative processing technology. During the mixing process at 88-90℃, the foaming masterbatch does not foam but undergoes a cross-linking reaction. Cooling and pelletizing with cold water protects the thermosensitive expandable microspheres, and underwater pelletizing facilitates subsequent processing. When the foaming masterbatch and PVC granules are extruded at 140-160℃, the foaming of the expandable microspheres increases the single-screw pressure, allowing for a more complete cross-linking reaction of SEBS and TBEC+TAIC, thereby improving the material's mechanical properties. Simultaneously, the improved mechanical properties after the cross-linking reaction, coupled with the mutual inhibition of micro-crosslinking and foaming, increase the closed-cell rate of the expandable microspheres, thus achieving dimensional control.

[0023] 3. This invention innovatively designs a synergistic composition of TBEC + expanded microspheres + SEBS + TAIC to jointly improve the low thermal conductivity and low-temperature resistance of the door seal material. By controlling the closed-cell structure, the thermal conductivity of the material can reach 0.14~0.16 W / (m·K). Through the improvement and reinforcement of the cross-linked network, the tensile strength of the material can reach 12~13 MPa, and the elongation at break can reach 330~380%. Through the improvement of the SEBS component, the low-temperature resistance of the material is significantly improved. Attached Figure Description

[0024] Figure 1 This is a microscope image of the side of the door seal material prepared in Example 2. Detailed Implementation

[0025] It should be noted that the raw materials used in the embodiments are from the following sources:

[0026] Organic expanded microspheres: Matsumoto Yushi-Seiyaku Co., Ltd;

[0027] AC foaming agent: Jinan Feiheng New Materials Co., Ltd.;

[0028] EVA: Yangzi Petrochemical-BASF Co., Ltd.;

[0029] POE: Mitsui Chemicals (China) Management Co., Ltd.;

[0030] SEBS: Sinopec Baling Petrochemical Company;

[0031] TBEC: Liaoning Zhongmao New Materials Co., Ltd.

[0032] TAIC: Hefei Anbang Chemical Co., Ltd.

[0033] PE wax: Hangzhou Wangjiang Oil & Chemical Co., Ltd., CH- type;

[0034] Stearic acid: Indonesia Green Treasure Group, type 1801;

[0035] EVA-g-MAH: Jiangsu Sirida Materials Technology Co., Ltd.;

[0036] PVC: Tianjin Dagu Chemical Co., Ltd., DG-800 type;

[0037] SBR: Sinopec Baling Petrochemical Company;

[0038] TPU: Huntsman Polyurethanes (China) Co., Ltd.

[0039] The group composition of each group during the preparation of foaming masterbatch in Examples 1-3 and Comparative Examples 1-5 is shown in Table 1.

[0040] Table 1. Components used in the preparation of foaming masterbatch in different embodiments and comparative examples (unit: g)

[0041] Example 1 80 120 (EVA) 20 (SEBS) 10 12 2 (Stearic acid) 6 Example 2 100 100 (EVA) 40 (SEBS) 16 24 3 (Stearic acid) 8 Example 3 120 80 (EVA) 30 (SEBS) 20 40 5 (Stearic acid) 10 Comparative Example 1 100 (AC foaming agent) 100 (EVA) 40 (SEBS) 16 24 3 (Stearic acid) 8 Comparative Example 2 100 100 (EVA) 40 (SBR) 16 24 3 (Stearic acid) 8 Comparative Example 3 100 100 (EVA) 40 (TPU) 16 24 3 (Stearic acid) 8 Comparative Example 4 100 100 (POE) 40 (SEBS) 8 16 3 (Stearic acid) 8 Comparative Example 5 100 100 (POE) 40 (SEBS) 23 28 3 (Stearic acid) 8

[0042] Preparation method:

[0043] ① Mix all raw materials evenly, knead at 88℃ for 10 minutes, and then granulate underwater in cold water to obtain foaming masterbatch.

[0044] ② Mix the PVC base material and foaming masterbatch evenly. The amount of foaming masterbatch added is 8% of the weight of the PVC base material. Use a single screw extrusion process and control the extrusion temperature at 155℃ to obtain PVC door seal material.

[0045] Performance testing:

[0046] ① Thermal conductivity: Tested according to standard GB / T 11205-2009, using the hot wire method for determining the thermal conductivity of rubber in that standard.

[0047] ②Tensile strength: Tested according to the method of standard GB / T 1040.3-2006.

[0048] ③ Elongation at break: Tested according to the method of standard GB / T 1040.1-2006.

[0049] ④ Low-temperature embrittlement temperature: The test shall be conducted in accordance with the method for testing the low-temperature embrittlement temperature of rubber in standard GB / T15256-2014.

[0050] ⑤ Weather resistance and color change: The fluorescent ultraviolet lamp / condensation test was conducted according to the provisions of GB16422.3 Plastics Laboratory Light Source Exposure Test Method, Part 3: Fluorescent Ultraviolet Lamps. Four 40W UVA-340 ultraviolet lamps were used at a distance of 5 cm, with a light intensity of 0.7 W / m. 2Under the conditions, the black mark temperature was 60 ± 3℃. Half of the sample surface was covered with aluminum foil and continuously irradiated for 48 h and 96 h. After the test, the colorimetric difference of the covered and uncovered parts was compared by colorimeter or visual inspection. A ΔE result <2 was considered normal, and a ΔE result ≥2 was considered yellowing.

[0051] Table 2 Performance tests of door seals prepared in different embodiments and comparative examples

[0052] Example 1 0.1522 12.1 330 -37 normal Example 2 0.1401 13.3 380 -40 normal Example 3 0.1378 12.4 350 -39 normal Comparative Example 1 0.1399 8.1 270 -30 normal Comparative Example 2 0.1403 13.4 385 -31 Turn yellow Comparative Example 3 0.1402 13.5 388 -37 Turn yellow Comparative Example 4 0.1410 11.5 301 -35 normal Comparative Example 5 0.1406 10.2 280 -32 normal

[0053] The experimental results are shown in Table 2. The tensile strength of the materials prepared in Examples 1-3 is greater than 12.1 MPa, the elongation at break is greater than 330%, the thermal conductivity is between 0.1378 and 0.1522 W / (m·K), the low-temperature embrittlement temperature is below -37 ℃, and the weather resistance is normal. These results indicate that the PVC door seal material prepared by this invention has good mechanical properties, low-temperature performance, thermal insulation performance, and weather resistance, and can meet the application requirements.

[0054] In Comparative Example 1, AC foaming agent was used instead of organic expandable microspheres. Since AC foaming agent is a gas-based foaming agent, the foaming process is relatively difficult to control precisely, easily leading to non-uniform cell structure, thus significantly reducing the tensile strength and elongation at break of the material. Although its thermal conductivity decreased slightly, the overall performance still did not meet the ideal requirements.

[0055] In Comparative Example 2, SBR was used instead of SEBS. This substitution slightly improved the tensile strength and elongation at break of the prepared door seal material, but its low-temperature embrittlement temperature increased significantly, indicating that the material's low-temperature performance deteriorated significantly. At the same time, its weather resistance was also unsatisfactory, indicating that SBR is not conducive to the long-term stable use of the material of this invention in low-temperature environments.

[0056] In Comparative Example 3, TPU was used instead of SEBS. The tensile strength, elongation at break, and low-temperature embrittlement temperature of this material were improved, but its weather resistance was unsatisfactory. This indicates that although TPU has certain advantages in some mechanical properties and low-temperature performance, it is difficult to meet the requirements for long-term weather resistance.

[0057] In Comparative Example 4, the amount of crosslinking agent was too low, making it difficult to form an effective crosslinking network, resulting in insufficient crosslinking and thus affecting the overall performance of the material. In Comparative Example 5, the amount of crosslinking agent was too high, easily causing over-crosslinking, which in turn led to local agglomeration or structural defects, reducing the tensile strength and elongation at break of the material, and also adversely affecting low-temperature performance. Therefore, the amount of TBEC needs to be controlled within an appropriate range; too low or too high a amount is detrimental to improving the overall performance of the material.

[0058] Depend on Figure 1It can be seen that in the low-temperature resistant and low-thermal-conductivity PVC door seal material prepared in Example 2, the organic expanded microspheres are distributed relatively evenly and the cell size is relatively consistent, indicating that the system can form a relatively stable microporous structure, which is beneficial to reducing the thermal conductivity of the material and maintaining good mechanical properties.

Claims

1. A foaming masterbatch, characterized in that, It consists of the following components in parts by weight: Solid foaming agent: Organic expanded microspheres, 100 parts; Foaming agent carrier: EVA, 80~120 parts; Synthetic rubber: SEBS, 20-40 parts; Initiator: 10-20 parts of tert-butyl peroxide-2-ethylhexyl carbonate (TBEC); Crosslinking agent: 1,3,5-triallyl-triazine-2,4,6(1H,3H,5H)-trione TAIC, 12~40 parts; Lubricant: PE wax or stearic acid, 2-5 parts; Compatibilizer: EVA-g-MAH, 6~10 parts; First, mix all the raw materials evenly, then knead them at a temperature of 88~90℃ for 5~15 minutes, and finally granulate them underwater in cold water to obtain foaming masterbatch.

2. A low-temperature resistant, low-thermal-conductivity PVC door sealing material, characterized in that, It is made from PVC base material and foaming masterbatch as described in claim 1, wherein the amount of foaming masterbatch added is 4% to 14% of the weight of PVC base material.

3. The preparation method of the low-temperature resistant, low-thermal-conductivity PVC door seal material as described in claim 2, characterized in that, First, the PVC base material and foaming masterbatch are mixed evenly, and then processed by single screw extrusion with the extrusion temperature controlled at 140~160℃ to obtain a low-temperature resistant, low thermal conductivity PVC door seal material.

4. A low-temperature resistant, low-thermal-conductivity PVC door seal, characterized in that, It is prepared from the low-temperature resistant, low-thermal-conductivity PVC door seal material as described in claim 2.

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