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The modification of polypropylene materials is generally through minerals reinforced toughening, weather modification, glass fiber reinforced, flame retardant modification and other ways. Each type of modified product has a large number of applications in the field of household appliances.
Mineral enhancement and toughening is one of the most common modifications. The minerals added to the polypropylene raw materials are usually calcium carbonate, talc, wollastonite, glass beads, mica powder and the like. These minerals can not only improve the mechanical properties and impact toughness of polypropylene materials to a certain degree, reduce the molding shrinkage of polypropylene materials to enhance their dimensional stability, and due to the huge difference in cost between minerals and polypropylene matrix, Can significantly reduce the cost of polypropylene materials. At present, the inner barrel of the washing machine and the drum washing machine is generally made of mineral reinforced and toughened polypropylene material instead of the early stainless steel inner tube. After the polypropylene material is reinforced and toughened by minerals, it can overcome the problems of insufficient original strength, poor gloss, and too much shrinkage. This modified polypropylene is used in the production of pulsator and pick-up parts in addition to the inner drum of the washing machine. The Haier Group only uses about 1700 tons per year (the weight of each inner tub 2kg). In addition, many parts of microwave ovens are also made of mineral reinforced toughened polypropylene materials. Due to the addition of minerals, the heat-resistant temperature of the polypropylene material itself can be further improved on the basis of the higher heat-resistant temperature of the polypropylene material so as to adapt to the high temperature requirement of the microwave oven. For example, microwave oven door seals, microwave oven speaker bells, horn mounts, etc., use this modified polypropylene material. In addition, the shelves on the refrigerator are now also basically using mineral reinforced toughened polypropylene material. Due to the integral injection molding with the glass panel, the problem of panel scumming of the original ABS material is well solved.
The weather-resistant modified polypropylene material is due to the unstable tertiary carbon group contained in the polypropylene. After the action of light, heat, and oxygen, it is prone to aging degradation, resulting in discoloration, strength reduction, and other issues, limiting its outdoor products. application. Therefore, through the weather modification of polypropylene, the service life of polypropylene materials in outdoor harsh weather conditions can be greatly improved. The modified material is mainly used for manufacturing household appliances that are exposed to the open air all the year round, and is particularly used in the manufacture of outdoor air-conditioner main-body casings to replace the conventional metal-sprayed plastic casings, thereby overcoming the existing production of the metal spray-molded casings. The process is complex, the cost is high, the weight is large, and the rust is easy (which can affect the performance and service life of the entire machine), and finally, the labor intensity of the workers is reduced, the energy consumption is reduced, and the service life is prolonged. This technology was first developed and put into use by Sumitomo Corporation and Mitsubishi Chemical Corporation in the early 1990s.
The glass fiber reinforced polypropylene material is polypropylene. The mechanical properties of the material vary greatly from the requirements of the engineering structure. Generally, the tensile strength is between 20-30MPa, the bending strength is between 25-50MPa, and the flexural modulus is 800- Between 1500MPa. If you want to use it in the engineering structure, you must use glass fiber for reinforcement. In general, the mechanical properties of glass fiber-reinforced polypropylene products can be doubled or even several times improved. Specifically, the tensile strength reaches 65 to 85 MPa, the bending strength reaches 70 to 95 MPa, and the flexural modulus reaches 3,000 to 4,500 MPa. This mechanical strength is completely comparable to ABS and reinforced ABS products and is more heat-resistant. Generally, the heat-resistant temperature of ABS and reinforced ABS is between 80°C and 98°C, while the heat-resistant temperature of glass-fiber-reinforced polypropylene material can reach 135°C-145°C. It can be used to make axial fans and cross-flow fans in refrigerators, air conditioners, and other refrigeration machines at a much lower cost than ABS-enhanced or AS-enhanced products. In addition, it can also be used to manufacture inner cylinders of high-speed washing machines to meet their high requirements for mechanical properties.
Fire-retardant modified polypropylene material is used to avoid fire. Nowadays, many countries require that the materials used in electronic and electrical components in household appliances must be flame-retardant. Generally, they must meet UL94 flame retardant rating V0. Because polypropylene belongs to flammable materials, it is generally used in the flame retardant modified Br/Sb composite system. Through the flame-retardant modification, polypropylene products can be extinguished in the event of fire, and can withstand 6500C or even 7500C glow wire without ignition. This flame-retardant modified polypropylene material is generally used for making components such as a washing machine control tray, a remote controller housing, a refrigerator evaporating dish, a ventilating duct, etc., which are potentially dangerous to burn.
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