Polyolefin and polystyrene alloy material, preparation method thereof and refrigerator liner

Abstract

The invention discloses a polyolefin and polystyrene alloy material, a preparation method thereof and a refrigerator liner. The alloy material is prepared from high-gloss HIPS, GPPS, ternary atactic polypropylene, LLDPE, a high-flow compatilizer and mica. Compared with a conventional HIPS box liner material, the alloy material has more excellent comprehensive mechanical properties, and the glossiness of an extruded plate is larger than 85 (60-degree angle). The alloy material has excellent heat resistance and solvent corrosion resistance, the refrigerator inner container formed through plastic uptake is free of the problems of cracking, sinking and deformation after being subjected to polyurethane high-temperature foaming, the alloy material has good cohesiveness with a polyurethane heat preservation material, the problem that a foaming layer falls off does not exist, and the problem that a conventional HIPS refrigerator inner container is prone to being corroded and cracked when meeting edible oil is solved. And the types of materials used by refrigerator factories are reduced, the energy consumption of forming processing is greatly reduced, and the economic benefits of the refrigerator factories are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyolefin alloy materials, and relates to a polyolefin and polystyrene alloy material suitable for extrusion thermoforming, a preparation method thereof, and a refrigerator inner liner. Background Art

[0002] Most of the existing refrigerator inner liners are made of HISP (high impact polystyrene) extrusion sheets and then vacuum thermoformed. However, in the process of producing and preparing the refrigerator liners, in order to control costs, it has become an industry consensus to use thinner sheets for thermoforming; but the thin-walled HIPS refrigerator liners are prone to solvent corrosion cracking during the foaming process of the refrigerator insulation material, and are prone to swelling and corrosion cracking by edible oil during normal use, resulting in a relatively high scrapping rate of the thin-walled refrigerator liners and causing waste of resources. Polyolefin materials have excellent oil resistance, chemical corrosion resistance, and stress cracking resistance. They are low in price, non-toxic, low in density, and low in odor during the processing process, and have become alternative materials for many materials in the household appliance industry; however, the melting temperature of polyolefin materials is higher than that of HIPS, and its softening point is very close to the melting point, with a narrow melting range, resulting in low melt strength and poor anti-drooping performance of the melt, making it difficult to thermoform some parts with complex structures; moreover, polyolefin materials are non-polar materials, and it is difficult for the prepared refrigerator inner liner parts to bond with the polyurethane insulation layer after assembly, resulting in a decrease in the refrigerator insulation effect. Therefore, it is necessary to improve the surface polarity by corona, plasma, flame, etc. treatment on the surface of the refrigerator liner to solve the problem of poor bonding with the polyurethane insulation layer. At the same time, in order to meet the high-gloss requirements of the conventional high-gloss refrigerator inner liner, it is necessary to co-extrude three layers of corrosion-resistant PS + conventional HIPS + high-gloss HIPS to meet the requirements, which not only increases the number of extruders and leads to higher extrusion energy consumption, but also increases the types and difficulties of raw material procurement in the refrigerator factory. Although the existing PS & polyolefin alloy materials can balance the thermoforming performance and improve the problem of poor oil corrosion resistance, the gloss of the prepared refrigerator liner is relatively low, and it is necessary to co-extrude with high-gloss HIPS to prepare a double-layer structure to meet the high-gloss requirements of the refrigerator liner. Since the addition of polyolefin will affect the interfacial bonding force between the PS & polyolefin alloy material and high-gloss HIPS, the high-gloss layer is easily torn off by the fixing tape during the refrigerator manufacturing process, resulting in product unqualified.

[0003] Patent CN112724514A uses PP resin, polystyrene, high impact polystyrene, talc powder, and compatibilizer to extrude sheets by high-temperature melting, making it have good oil resistance and corrosion resistance. However, the gloss of the prepared alloy material is low, and at the same time, it does not evaluate the bonding effect between the material and the polyurethane insulation layer.

[0004] Patent CN109438602 uses a catalyst with a wide molecular weight distribution to prepare a special polypropylene that is easy to thermoform. This material has the characteristics of low processing temperature, high melt strength, and good fluidity. However, the impact performance of this material at normal and low temperatures is low and cannot meet the requirements of the low-temperature performance of the refrigerator inner liner.

[0005] Patent CN106700375 uses high-impact polystyrene, polyethylene, and compatibilizer to prepare a corrosion-resistant PS / PE alloy material. However, the tensile strength and flexural modulus of this alloy material are relatively low, which easily leads to the depression of the refrigerator liner after foaming. Moreover, the glossiness of this alloy material is low and it is impossible to prepare a high-gloss refrigerator inner liner.

[0006] Patent CN105504638 uses high-impact polystyrene, polyethylene, compatibilizer, and naphthenic oil to prepare a PS / PE alloy material for injection molding to prepare refrigerator end cap materials. However, this alloy material uses polyethylene material and cannot meet the high-temperature resistance requirements of thin-wall liners. And the thickness of the injection-molded parts is relatively thick, and its high-temperature resistance defects are not easy to be found. At the same time, naphthenic oil is added by blending, which makes it easy to precipitate during the later use process, resulting in the problem of sticky surface of the parts.

[0007] Patent CN105061880 uses general-purpose polystyrene, high-density polyethylene, linear low-density polyethylene, compatibilizer, and toughening agent to prepare a PS / PE alloy material. Its formulation system uses a large amount of polyethylene resin, resulting in lower flexural strength and flexural modulus of the material and reduced heat resistance, making the liners prepared from it prone to defects such as depression during high-temperature foaming.

[0008] It can be seen that there are still many problems in the application of existing polyolefin & polystyrene alloy materials suitable for extrusion thermoforming to refrigerator inner liner parts. Summary of the Invention

[0009] The purpose of the present invention is to address the above-mentioned drawbacks in the prior art and provide a polyolefin and polystyrene alloy material suitable for extrusion thermoforming and its preparation method. This alloy material has more excellent comprehensive mechanical properties compared with conventional HIPS liner materials. Moreover, the softening temperature of this material is low, making its preheating and softening speed fast in the early stage of thermoforming, which is beneficial to rapid molding. The glossiness of the sheet extruded from this material > 85 (60° angle), which can meet the requirements of high-gloss refrigerator inner liners. This alloy material has excellent solvent corrosion resistance. The refrigerator inner liner formed by thermoforming has no problems such as cracking and depression deformation after polyurethane high-temperature foaming, and has good adhesion with polyurethane thermal insulation materials, and there is no problem of the foaming layer falling off, solving the problem of easy corrosion and cracking of conventional HIPS liners when exposed to edible oil.

[0010] To achieve the above invention purpose, the present invention adopts the following technical solutions:

[0011] A polyolefin and polystyrene alloy material suitable for extrusion thermoforming, comprising the following raw materials in parts by mass:

[0012] 20 - 60 parts of high-gloss HIPS resin,

[0013] 10 - 40 parts of GPPS resin,

[0014] 8 - 20 parts of random terpolymerized polypropylene resin,

[0015] 10 - 20 parts of LLDPE resin,

[0016] 5 - 20 parts of high-flow compatibilizer resin,

[0017] 5 - 8 parts of mica,

[0018] 0.2 - 1 part of lubricant,

[0019] 0.1 - 0.5 part of nucleating agent,

[0020] 0.2 - 1 part of antioxidant.

[0021] In the present invention, the melt index of the high-gloss HIPS resin is 3 - 15 g / 10 min (200 °C, 5 kg). For example, Chi Mei PH-888G, Sumitomo Chemical HIPS1180, Ineos HIPS576H, etc.

[0022] In the present invention, the melt index of the GPPS resin is 10 - 20 g / 10 min (200 °C, 5 kg). For example, Ineos GPPS2601, Formosa Plastics GP5000, Ineos GPPS2601, etc.

[0023] In the present invention, the melt index range of the random terpolymerized polypropylene resin is 5 - 20 g / 10 min (230 °C, 2.16 kg), and 130 °C ≤ melting temperature ≤ 145 °C. For example, TPC FL7540L, TPC FL7632L, Lotte SFC-750, etc.

[0024] In the present invention, the melt index range of the LLDPE resin is 3 - 30 g / 10 min (190 °C, 2.16 kg), and preferably it is LLDPE synthesized by metallocene catalyst. For example, ExxonMobil 3518PA, Dow Chemical 5220G, etc.

[0025] In the present invention, the high-flow compatibilizer is polystyrene-ethylene-propylene-styrene or polystyrene-ethylene-butene-styrene block copolymer, the mass fraction of styrene in the block copolymer is 12 - 30%, and the melt index range of the block copolymer is 5 - 20 g / 10 min (230 °C, 5 kg). For example, Taixiang SEBS 6014, Taixiang SEBS 6152, etc.

[0026] In the present invention, the lubricants are respectively amide lubricants and / or stearic acid lubricants, preferably ethylene bisstearamide and / or zinc stearate.

[0027] In the present invention, the mica is phlogopite with good heat resistance.

[0028] In the present invention, the nucleating agent is a polypropylene β-nucleating agent. For example, TMB-5 from Shanxi Research Institute of Chemical Industry, NAB-83 from Guangdong Chenghe Co., Ltd., etc.

[0029] In the present invention, the antioxidant is any one or more of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants. For example, hindered phenol antioxidant 1010, phosphite antioxidant 168, thioester antioxidant DSTDP, etc.

[0030] In the present invention, the method for preparing a polyolefin and polystyrene alloy material suitable for extrusion thermoforming includes the following steps:

[0031] Step (1): Mix a random terpolymerized polypropylene resin, an LLDPE resin, a high-flow compatibilizer resin, a lubricant, a nucleating agent, and an antioxidant, and feed them into the main feeding port of a twin-screw extruder. After high-temperature melting and dispersion, pelletize by extrusion to obtain modified resin 1.

[0032] Step (2): Mix modified resin 1, a high-gloss HIPS resin, and a GPPS resin, and feed them into the main feeding port of a twin-screw extruder. Feed mica into the side feeding port of the twin-screw extruder. After high-temperature melting and dispersion, pelletize by extrusion to obtain a polyolefin and polystyrene alloy material suitable for extrusion thermoforming.

[0033] In the present invention, the ratio of the length to the diameter of the screw of the twin-screw extruder in step (1) is (40 - 52):1, the screw rotation speed is 500 - 700 r / min, and the extrusion temperature is 210 - 230 °C.

[0034] In the present invention, the ratio of the length to the diameter of the screw of the twin-screw extruder in step (2) is (40 - 52):1, the screw rotation speed is 300 - 400 r / min, and the extrusion temperature is 210 - 230 °C.

[0035] The polyolefin and polystyrene alloy material of the present invention can be used to prepare a high-gloss refrigerator inner liner with excellent solvent resistance and corrosion and crack resistance, and has good adhesion to polyurethane foaming material.

[0036] A high-gloss single-layer thin-wall refrigerator inner liner is prepared from the polyolefin and polystyrene alloy material described in the present invention. The types of materials used in the refrigerator factory are reduced, and the extrusion molding is simplified from the original three extruders to one extruder. The thermoforming process of the alloy material is the same as that of the conventional HIPS material, significantly reducing the energy consumption of the forming process and improving the economic benefits of the refrigerator factory.

[0037] The technical solution of the present invention has the following advantages over the prior art solution:

[0038] (1) The PS resins used in the present invention are high-gloss HIPS and GPPS. The rubber phase contained in the high-gloss HIPS itself has a small size and has no influence on the forming surface, so it has excellent gloss. GPPS has no rubber phase and also has excellent gloss. For traditional HIPS resins, in order to improve the impact resistance, the size of the rubber phase will be larger, so it is impossible to achieve a high-gloss surface effect. Using a certain proportion of PS resin as the matrix resin can, on the one hand, take into account the thermoforming efficiency of the material, and on the other hand, can improve the surface polarity of the material to ensure the bonding effect between the prepared and formed inner liner and the polyurethane foaming material.

[0039] (2) The polyolefin materials used in the alloy material of the present invention are random terpolymerized polypropylene resin and metallocene LLDPE. Using only PE as the corrosion-resistant component can improve the anti-foaming agent and oil corrosion resistance of the alloy material. However, with the improvement of the foaming efficiency of the inner liner, the temperature of the polyurethane foaming material during the foaming process will be higher than 100 °C. The inner liner prepared using only PE as the corrosion-resistant component is easily deformed by heat, and is prone to problems such as inner liner concavity and inner liner deformation, resulting in the scrapping of the refrigerator. Using the compound of random terpolymerized polypropylene resin and LLDPE can improve the heat resistance of the alloy material and solve the problems of easy concavity and deformation of the inner liner due to heat. Moreover, compared with conventional block or homopolymerized polypropylene resins, random terpolymerized polypropylene has a relatively low melting point and a relatively wide melting range, which can take into account a relatively high thermoforming efficiency and a relatively low thermoforming energy consumption. And random terpolymerized polypropylene uses a β-nucleating agent to induce the formation of β-crystals, which can improve the low-temperature toughness and anti-cracking performance of the material.

[0040] (3) The compatibilizer used in the present invention is a high-flow polystyrene-ethylene-propylene-styrene or polystyrene-ethylene-butene-styrene block copolymer. Compared with traditional SBS, it does not contain unsaturated double bonds and has excellent processing stability and aging resistance. The ethylene-propylene block or ethylene-butene block it contains has a similar structure to random terpolymerized polypropylene and LLDPE, and has excellent compatibility; due to the high fluidity and good compatibility of the selected compatibilizer, it is easy to disperse the polyolefin component into small-particle-size components during the shear dispersion process, ensuring the surface gloss of the final alloy material.

[0041] (4) The extrusion process used in the present invention is a two-step method. In the first step, the polyolefin component and the high-flow compatibilizer are extruded and dispersed. A high-speed extrusion process is adopted to ensure that the polyolefin component is pre-mixed with the compatibilizer sufficiently to form a good wrapping effect, ensuring the particle size requirement of the dispersed phase in the final alloy material, so as to meet the requirement of high gloss of the alloy material. In the second extrusion process, medium and low speeds are adopted. On the one hand, it ensures the effective dispersion of the PS, polyolefin & compatibilizer components. On the other hand, it ensures the morphology retention of the flaky mica in the material and avoids the damage of its lamellar structure by high speed, thereby improving the mechanical properties and barrier properties of the alloy material and enhancing the anti-deformation ability and corrosion resistance of the box liner. Detailed implementation mode

[0042] To better understand the technical solution of the present invention, the content of the present invention will be further elaborated below in conjunction with embodiments. However, the content of the present invention is not limited to the following embodiments. Unless otherwise specified, the raw materials used in the examples or comparative examples are all commercially available raw materials.

[0043] The devices and main raw material sources used in the examples and comparative examples of the present invention are as follows:

[0044] Twin-screw extruder: Model CTE-35, screw length-diameter ratio 48:1, Coperion (Nanjing) Machinery Co., Ltd.

[0045] High-gloss HIPS resin: PH-888G, melt index 4 g / 10 min (200 °C, 5 kg), Chi Mei Industries Co., Ltd.

[0046] Ordinary HIPS resin: HIPS2710, melt index 4.5 g / 10 min (200 °C, 5 kg), Yangzi Petrochemical-BASF Co., Ltd.

[0047] GPPS resin: GPPS2601, melt index 11 g / 10 min (200 °C, 5 kg), Ineos Styrolution Group Ltd.

[0048] Ternary random polypropylene resin: FL7540L, melt index 7 g / 10 min (230 °C, 2.16 kg), TPC Corporation

[0049] Block copolymerized polypropylene resin: PP8285E1, melt index 30 g / 10 min (230 °C, 2.16 kg), ExxonMobil Chemical Company

[0050] LLDPE resin: 3518PA, melt index 3.5 (190 °C, 2.16 kg), ExxonMobil Chemical Company

[0051] High-flow compatibilizer resin: SEBS 6014, melt index is 6 (230 °C, 5 kg), Taixiang Co., Ltd.

[0052] Common compatibilizer resin: SBS1401, melt index is 2.3 (230 °C, 5 kg), Yanshan Petrochemical Co., Ltd.

[0053] Mica: 150-S, IMERYS

[0054] Lubricant: Zinc stearate, Faji Co., Ltd.

[0055] β-nucleating agent: TMB-5, Shanxi Research Institute of Chemical Industry

[0056] Antioxidant: Antioxidant 1010, belonging to hindered phenol catalysts, BASF (BASF (China) Co., Ltd.);

[0057] Antioxidant: Antioxidant 168, belonging to phosphite catalysts, BASF (BASF (China) Co., Ltd.);

[0058] The performance characterization methods of the materials in the present invention are as follows:

[0059] Flexural modulus: GB / T 9341-2008;

[0060] Tensile strength: GB / T 1040.2-2006;

[0061] Izod impact strength: GB / T 1843-2008;

[0062] Surface glossiness: ISO2813;

[0063] Test method for solvent resistance of materials: Fix the tensile specimen to the ESCR mold, with the mold bending strain of 2%, place it in a pressure-resistant corrosion tank containing the foaming agent cyclopentane liquid, the temperature in the tank is 40 ± 1 °C, keep it for 4 h, take out the specimen after corrosion, and place it for 24 h for tensile strength test.

[0064] Test for forming time of box liner: Extrude the sheet of alloy material on the thermoforming equipment for box liner thermoforming, keep the power of the heating tile during thermoforming unchanged, investigate the forming cycle of different alloy materials by adjusting the heating time, and investigate the thermoforming time of the materials by the number of box liners formed per hour. The more the number, the higher the efficiency.

[0065] Test method for bonding effect of polyurethane foam: Place the refrigerator inner liner parts in the foaming mold, add polyol, isocyanate, and foaming agent for foaming. After foaming is completed, take out the inner liner parts and place them for 24 h. Cut out a 100 mm * 100 m plane on the inner liner parts with a knife and then conduct a peel test to check the bonding situation of the polyurethane foam on the material surface.

[0066] High and low temperature test method for thermoformed refrigerator inner liner parts: Place the foamed refrigerator in a high and low temperature test chamber. The test time for each temperature is 12 hours. The high temperature is 70 ± 5 °C, and the low temperature is -40 ± 5 °C. One cycle consists of one high temperature and one low temperature test, and a total of 3 cycles are carried out. Observe the appearance of the inner liner surface after the test.

[0067] Oil corrosion resistance test method for thermoformed refrigerator inner liner parts: After the refrigerator is assembled by foaming, apply chili oil on its inner liner and then plug it in to run. Reapply chili oil every week to ensure that there is always oil on the inner liner. Observe whether there is any abnormality on the inner liner after continuous operation for 2 months.

[0068] Examples 1-4 (i.e., S1-4) and Comparative Examples 1-7 (i.e., D1-7), prepare the alloy materials according to the raw materials and dosages in Table 1.

[0069] Example 1

[0070] Step (1): Mix 9.2 parts of FL7540L, 10 parts of 3518PA, 5 parts of SEBS 6014, 0.3 parts of zinc stearate, 0.1 part of TMB-5, 0.2 parts of 1010, and 0.2 parts of 168, and feed them from the main feeding port of the twin-screw extruder. The rotation speed of the extruder is 700 r / min. After high-temperature melting and dispersion, pelletize to obtain modified resin 1.

[0071] Step (2): Mix 25 parts of modified resin 1, 30 parts of PH-888G, and 40 parts of GPPS2601, and feed them from the main feeding port of the twin-screw extruder. Feed 5 parts of 150-S from the side feeding port of the twin-screw extruder. The rotation speed of the extruder is 400 r / min. After high-temperature melting and dispersion, pelletize to obtain a polyolefin and polystyrene alloy material suitable for extrusion and thermoforming.

[0072] Examples 2-4

[0073] Prepare the alloy materials according to the raw materials and dosages in Table 1. The specific preparation method is the same as that of Example 1.

[0074] Comparative Examples 1-7

[0075] Prepare the alloy materials according to the raw materials and dosages in Table 1. The specific preparation method is the same as that of Example 1.

[0076] Comparative Example 8

[0077] Mix 20 parts of PH-888G, 10.8 parts of GPPS2601, 20 parts of FL7540L, 20 parts of 3518PA, 20 parts of SEBS 6014, 8 parts of 150-S, 0.3 part of zinc stearate, 0.5 part of TMB-5, 0.2 part of 1010, and 0.2 part of 168, and feed them into the main feeding port of a twin-screw extruder. The rotational speed of the extruder is 700 r / min. After high-temperature melting and dispersion, pelletize by extrusion to obtain an alloy material.

[0078] Table 1 Raw materials and their dosages in Examples 1-4 and Comparative Examples 1-8

[0079]

[0080]

[0081] Table 2 Performance test results of Examples 1-4 and Comparative Examples 1-8, and HIPS2710

[0082]

[0083]

[0084] As can be seen from Table 2, the PS resins used in Examples 1 to 4 are high-gloss HIPS and GPPS, which inherently have excellent gloss. When combined with high-flow polystyrene-ethylene-propylene-styrene or polystyrene-ethylene-butene-styrene block copolymers, the ethylene-propylene block or ethylene-butene block they contain is similar in structure to that of terpolymer random polypropylene and LLDPE, and has excellent compatibility. Since the selected compatibilizer has high fluidity and good compatibility, it is easy to disperse the polyolefin component into small-particle-size components during the high-speed shear dispersion process in the first step of the two-step method, ensuring the surface gloss of the final alloy material. The gloss of the alloy materials in Examples 1 to 4 all meets the requirements for high-gloss inner linings (at a 60° angle, gloss > 85). In the second extrusion process, medium and low speeds are used. On the one hand, it ensures the effective dispersion of the PS, polyolefin & compatibilizer components, and on the other hand, it ensures the morphology retention of the flaky mica in the material, avoiding the damage of its lamellar structure by high speeds, thereby improving the mechanical properties and barrier properties of the alloy material, and greatly enhancing the anti-deformation ability and oil corrosion resistance test ability of the inner lining during high and low temperature tests. The polyolefin system of the alloy materials in Examples 1 to 4 uses a blend of terpolymer random copolymer polypropylene resin and LLDPE. On the one hand, the low-temperature plasticization ability of the LLDPE resin is utilized to improve the thermoforming efficiency of the alloy material. Using the terpolymer random copolymer polypropylene resin can improve the heat resistance of the alloy material in the LLDPE system and solve the problems of easy denting and deformation of the inner lining when heated. Moreover, compared with conventional block or homopolymer polypropylene resins, the terpolymer random copolymer polypropylene has a relatively low melting point and a relatively wide melting range, which can balance a relatively high thermoforming efficiency and a relatively low thermoforming energy consumption. In addition, the terpolymer random copolymer polypropylene uses a β-nucleating agent to induce the formation of β-crystals, which can enhance the low-temperature toughness and anti-cracking performance of the material.

[0085] In Comparative Example 1, the matrix resin used was conventional HIPS 2710, which had a relatively large rubber phase size, resulting in a lower surface gloss of the product and failing to meet the requirements of a high-gloss inner liner. In Comparative Example 2, the polyolefin component used was a combination of block copolymerized polypropylene and LLDPE. Since the block copolymerized polypropylene itself had a low gloss, the gloss of the alloy material was low. At the same time, the melting temperature of the block copolymerized polypropylene was 165 °C, much higher than that of the terpolymer random copolymerized polypropylene, resulting in a significant reduction in its thermoforming efficiency. In Comparative Example 3, mica filler was not used. Compared with Example 1, its tensile and flexural properties decreased to a certain extent. Moreover, the lamellar structure of mica had good barrier properties and anti-deformation ability. The lack of mica filler led to the problem of inner liner concave deformation in the high and low temperature tests of Comparative Example 3, and there was one crack in the oil corrosion resistance. In Comparative Example 4, the polyolefin component used was LLDPE, and the terpolymer random copolymerized polypropylene was not added, resulting in poor heat resistance and the problem of inner liner concave deformation in the high and low temperature tests of the box inner liner. In Comparative Example 5, the polyolefin component used was the terpolymer random copolymerized polypropylene, and LLDPE was not added, resulting in a significant reduction in its thermoforming efficiency. At the same time, LLDPE had more excellent low-temperature toughness than the terpolymer random copolymerized polypropylene, resulting in the problem of inner liner cracking in the high and low temperature tests. In Comparative Example 6, the high-flow compatibilizer was not used, making the compatibility between the PS and polyolefin components poor, resulting in poor overall mechanical properties of the material and the problems of cracking and inner liner concavity in the box inner liner. In Comparative Example 7, the compatibilizer used was SBS 1401. Since its compatibilizing effect on PS and polyolefin was worse than that of the high-flow SEBS, the material had a lower gloss and poor high and low temperature resistance. In Comparative Example 8, one-step direct extrusion was used, which would cause serious shearing of mica during the extrusion process, making its stiffening and barrier properties worse, resulting in the problem of inner liner concave deformation in the high and low temperature tests and cracking problems in the oil corrosion resistance. The HIPS material in Comparative Example had poor resistance to foaming agent corrosion and poor rigidity, resulting in the problem of inner liner concavity in the high and low temperature tests and multiple cracking problems in the box inner liner during the oil corrosion process.

[0086] The above description of the embodiments is for the convenience of those skilled in the art of this technical field to understand and apply the present invention. Those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the embodiments here. The improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A polyolefin and polystyrene alloy material, comprising the following raw materials in parts by mass: 20 - 60 parts of high-gloss HIPS resin, 10 - 40 parts of GPPS resin, 8 - 20 parts of random terpolymerized polypropylene resin, 10 - 20 parts of LLDPE resin, 5 - 20 parts of high-flow compatibilizer resin, 5 - 8 parts of mica, 0.2 - 1 part of lubricant, 0.1 - 0.5 part of nucleating agent, 0.2 - 1 part of antioxidant.

2. The alloy material according to claim 1, wherein, the melt index of the high-gloss HIPS resin is 3 - 15 g / 10 min, and the test conditions are 200 °C and 5 kg.

3. The alloy material according to claim 1 or 2, wherein, the melt index of the GPPS resin is 10 - 20 g / 10 min, and the test conditions are 200 °C and 5 kg.

4. The alloy material according to any one of claims 1 - 3, wherein, the melt index range of the random terpolymerized polypropylene resin is 5 - 20 g / 10 min, the test conditions are 230 °C and 2.16 kg, and 130 °C ≤ melting temperature ≤ 145 °C.

5. The alloy material according to any one of claims 1 - 4, wherein, the melt index range of the LLDPE resin is 3 - 30 g / 10 min, and the test conditions are 190 °C and 2.16 kg.

6. The alloy material according to any one of claims 1 - 5, wherein, the high-flow compatibilizer is polystyrene-ethylene-propylene-styrene or polystyrene-ethylene-butene-styrene block copolymer, the mass fraction of styrene in the block copolymer is 12 - 30%, and the melt index range of the block copolymer is 5 - 20 g / 10 min, and the test conditions are 230 °C and 5 kg.

7. The alloy material according to any one of claims 1 - 6, wherein, the lubricants are amide lubricants and / or stearic acid lubricants, preferably ethylene bisstearamide and / or zinc stearate; the mica is phlogopite with good heat resistance; the nucleating agent is a polypropylene β-nucleating agent; the antioxidant is any one or more of hindered phenol antioxidants, phosphite antioxidants and thioester antioxidants.

8. A method for an alloy material according to any one of claims 1 - 7, comprising the following steps: Step (1): Mix the random terpolymerized polypropylene resin, LLDPE resin, high-flow compatibilizer resin, lubricant, nucleating agent and antioxidant, and feed them from the main feeding port of a twin-screw extruder, and after high-temperature melting and dispersion, extrude and pelletize to obtain modified resin 1; Step (2): Mix modified resin 1, high-gloss HIPS resin and GPPS resin, and feed them from the main feeding port of a twin-screw extruder, and feed mica from the side feeding port of the twin-screw extruder, and after high-temperature melting and dispersion, extrude and pelletize.

9. The method according to claim 8, wherein, The L / D ratio of the screw of the twin-screw extruder in the step (1) is 40-52:1, the screw rotation speed is 500-700 r / min, and the extrusion temperature is 210-230 °C; the L / D ratio of the screw of the twin-screw extruder in the step (2) is 40-52:1, the screw rotation speed is 300-400 r / min, and the extrusion temperature is 210-230 °C.

10. A high-gloss single-layer thin-wall refrigerator inner liner is prepared by using the alloy material described in any one of claims 1-7 or the alloy material prepared by the method described in claim 8 or 9.

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