What are the modification technologies of plastic modifiers?
First, enhance technology
Fiber reinforcement is an important method for plastic modification. Both magnesium salt whisker and glass fiber can effectively improve the comprehensive properties of polypropylene.Polypropylene reinforced with glass fiber has the advantages of low density, low price and can be recycled. It is gradually replacing engineering plastics and metals in the application of automobile instrument panel, automobile body and chassis parts: Compared with glass fiber, magnesium salt whisker molding products have higher accuracy, dimensional stability and surface finish, suitable for the preparation of a variety of complex shape parts, light and high strength flame retardant parts and electronic and electrical parts. As a modifier, magnesium salt whisker can greatly improve the strength, stiffness, impact resistance and flame retardant properties of polypropylene.Therefore, the application of magnesium salt whisker and glass fiber in polypropylene modification has been paid more and more attention.
Two, toughening technology
Mineral enhancement and toughening is one of the most common modification methods. Minerals added to polypropylene raw materials are usually calcium carbonate, talc powder, wollastonite, glass beads, mica powder, etc. These minerals can not only improve the mechanical properties and impact toughness of polypropylene materials to a certain extent, reduce the molding shrinkage rate of polypropylene materials to strengthen its dimensional stability, and because of the huge difference in cost between minerals and polypropylene matrix, can greatly reduce the cost of polypropylene materials.
Mineral reinforced toughened polypropylene is one of the most widely used modified polypropylene materials in household appliances. The inner barrel of wave washing machines and drum washing machines is generally made of mineral reinforced and toughened polypropylene, instead of the earlier stainless steel inner barrel. Polypropylene material by mineral reinforcement toughened, can overcome the original strength is insufficient, glossiness is not good, shrinkage is too big and other problems.Haier alone consumes about 1,700 tonnes of the modified polypropylene a year (each washing machine cartridge weighs about 2kg), as well as parts such as corrugators and mouthpieces. The mineral content of this material is as high as 40%, its tensile strength can reach 33Mpa, elongation at break can reach more than 90%, notch impact strength is about 10KJ/m2.
Many parts of the microwave oven are also made of mineral-reinforced and toughened polypropylene. Due to the addition of minerals, the heat resistant temperature can be further improved on the basis of the high heat resistant temperature of polypropylene material itself, so as to meet the high temperature requirements of microwave oven. For example, this modified polypropylene material is used in the sealing strip of the microwave door body, the horn mouth of the microwave oven speaker, and the horn bracket. The shelf on the refrigerator is also basically made of mineral reinforced and toughened polypropylene material, due to the overall injection molding with the glass panel, so as to solve the original ABS material panel qinling problem.
Three, filling modification
A new type of highly packed glass fiber modified plastic can overcome the defects of conventional glass fiber reinforced thermoplastics. This material is based on high-temperature thermoplastics such as liquid crystal polymers, polyether sulfone, polyether imide and polyphenylene sulfide. When the filling amount of glass fiber is 80%, the modified material still has good machinability. The parts produced with the new materials have good characteristics of abrasion resistance and temperature change resistance. This new material can be bonded with plastic and metal, suitable for surface molding equipment processing, potential applications include automotive and fuel system components, bearings, electronic parts, scratch resistant enclosures, etc. The complementary benefits of this glass reinforcement are good flame retardant, recyclable, high heat resistance and dimensional stability.
Iv. Blending and plastic alloy technology
Plastic blending modification refers to a modification method in which one or more other resins (including plastics and rubber) are incorporated into a resin to change the properties of the original resin. Fluorine plastic alloy is the domestic existing ultra high molecular weight polyperfluoropepropylene (FER) as the main raw material, and PTFE filler directly mixed, with the physical method of manufacturing, the material performance exceeds the world recognized “plastic king” polytetrafluoroethylene.
Five, flame retardant technology
Polymer flame retardant technology, currently mainly to add bromo-based flame retardants, commonly used decabromodiphenyl ether, octabromodiphenyl ether, tetrabromodiphenol A, hexabromocyclododecane, especially in the use of decabromodiphenyl is the largest, bromo-based epoxy resin because of its excellent melt flow rate, high flame retardant efficiency, excellent thermal stability and light stability,And can make the flame retardant material has good physical and mechanical properties, no frost, so it is widely used in PBT, PET, ABS, nylon 66 and other engineering plastics, thermoplastic to PC/ABS plastic alloy flame retardant treatment.
The other varieties of flame retardants in the family are phosphorus series, triazine series, silicon series, expansion type, no type, etc. These flame retardants in a variety of different fields play their own unique flame retardant effect. In the phosphorous flame retardant, the varieties of organophosphorus are mostly oil liquid, not easy to add in the polymer processing process, generally used in polyurethane foam, transformer oil, cellulose resin, natural and synthetic rubber. Red phosphorus in inorganic phosphorus is a pure flame-retardant element with good flame-retardant effect, but its color is bright, so its application is partially limited. The application of red phosphorus should pay attention to the microparticles and surface coating, so that it has a better dispersion in polymer, high compatibility with polymer is good, not easy to migrate, can keep the polymer inflammability for a long time.
