Polypropylene (PP)
Source: China polypropylene network - China Fiber Network's website added: amy69 Add time: 2009-6-15
Polypropylene (propylene):
(1) Production Process of Polypropylene (PP) Polypropylene is obtained by adding polyacrylic acid, CH2=CHCH3, under the action of a ZN metal catalyst.
(2) Production method of polypropylene (PP):
1 slurry method. Polymerization in a diluent such as hexane is the first industrialization and the largest production method to date.
2 liquid phase bulk method. Polymerization was carried out in liquid propylene at 70 ° C and 3 MPa.
3 gas phase method. The polymerization is carried out under conditions in which propylene is in a gaseous state. The latter two methods do not use thinner, the process is short, and the energy consumption is low. The liquid phase bulk method has now shown an advantage in the later stage, and the gas phase method is also rapidly developing.
1. The classification of PP is divided into isotactic and atactic according to the structure.
The commonly used polypropylenes are all isotactic polypropylene.
2. Characteristics of PP Its molecular structure is similar to that of polyethylene, but the carbon atoms on the carbon chain carry a methyl group (–CH3). Polypropylene is slightly more brittle than polyethylene and has a melting temperature of 160 °C.
Usually a translucent, colorless solid, odorless and non-toxic.
Due to the regular structure and high crystallization, the melting point is as high as 167 ° C, heat resistance, steam sterilization of products can be its outstanding advantages.
With a density of 0.90g/cm3, it is the lightest general purpose plastic.
Corrosion resistance, tensile strength 30MPa, strength, rigidity and transparency are better than polyethylene.
The disadvantage is that it is poor in low temperature impact resistance and easy to age, but can be overcome by modification and addition of antioxidants.
3, PP application (1) injection molding products: is the largest application area of ​​polypropylene, products have turnover boxes, containers, suitcases, automotive parts (automotive interior parts, such as dashboard, fenders, ventilation pipes, fans , bumpers), household appliance parts, medical equipment (disposable syringes), instruments (dishwasher door liners, dryer vents, washing machine frames and covers, refrigerator door liners, etc., consumer goods (turf and Gardening equipment such as lawn mowers and sprinklers, etc.) and furniture.
(2) Extrusion products: made of polypropylene fiber, can also be made into polypropylene film, wherein the strength and transparency of the biaxially stretched film are greatly improved, and it is an important polymer material for packaging.
Polypropylene is the most versatile general-purpose plastic, which can be used as a plastic or as a fiber (polypropylene). Polypropylene is a low-absorbency, high-corrosion-resistant fiber that can be used in clothing and furniture, especially for woven carpets. It can also be extruded or blown into a film, and then drawn into a flat yarn, a woven bag, or a tying material - a strap. In recent years, polypropylene composite film has developed rapidly, and it can be used for moisture protection, gas barrier and cooking, and is used as a soft package for food and beverage.
Polypropylene pipes are used to transport hot water – PPR pipes, industrial wastewater and chemicals.
The plates are used to make containers.
(3) Thermoformed products: The flakes are thermoformed into thin-walled products for use as a single-use food container-drinking cup.
Others, such as blow molded products, are widely used in food packaging, such as yogurt containers, hot-filled beverage bottles. toy. Blocked polypropylenes with isotactic and random segments, respectively, can also be produced by special catalytic methods (metallocene catalysis). The properties of this polypropylene are similar to rubber.
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