Views:95 Author:Site Editor Publish Time: 2019-10-14 Origin:Site
At present, vacuum cleaners in the market contain plastic components. In order to improve the service life and outward appearance of vacuum cleaners, what should be paid attention to in vacuum cleaner materials selection and plastic coloring? Below we mainly introduce the rules of four plastic material selection and two common plastic coloring methods.
1)Heat-resistant Plastic Selection
Compared with traditional materials such as metal, ceramics and glass, one of the disadvantages of plastic is that the heat resistance is not high, which often limits its use in high temperature applications. Heat resistant plastic refers to those products which has a heat deflection temperature of 200 ° C or higher The indicators for measuring the heat resistance of plastic products are heat deflection temperature, Martin heat resistance temperature and Vicat softening point. Among them, the heat deflection temperature is the most commonly used. The relationship between the three properties of the same plastic is as follows: Vicat softening point>heat deflection temperature > Martin heat resistance temperature. For ABS, the corresponding values of the three heat-resistant temperatures are 160 ° C, 86 ° C, 75 ° C.
The heat deflection temperature mainly measures the rigidity of the plastic at a high temperature. The high heat deflection temperature means that the rigidity is still excellent at higher temperatures, and the low heat deflection temperature means that the softness is slightly worse at higher temperatures. The heat deflection temperature is closely related to the melting point, and the material having a high melting point always has a high heat deflection temperature.
Principles of heat-resistant plastic selection
①Consider the heat resistance level
A. It can be used to meet the heat resistance requirement. Do not choose too high heat resistance, it will increase the cost.
B. Use general modification plastic whenever possible. Most of the heat-resistant plastic belong to special plastics, the price is high, however, the price of general-purpose plastics is low.
②Consider environmental factors of heat-resistant
A. Instant heat resistance and long-term heat resistance. The heat resistance of plastics can be divided into instant heat resistance and long-term heat resistance.
B. Dry heat and wet heat. For hygroscopic plastic, the heat resistance is different under different dry and wet conditions. Take PA plastic as an example, the heat resistance is high under dry conditions and the heat resistance under wet conditions is low.
C. Resistance to media corrosion.
D. Aerobic heat or anaerobic heat
2)The Principle of Toughened Plastic Selection
Generally used in shells, the material is required to have the following properties while with excellent impact performance :
①Good processing fluidity (MI), which is suitable for the thin wall of shell products.
②The surface gloss and hardness of the products are high and the coloring performance is good.
③Enough mechanical strength.
④Good flame resistance, oxygen index should be above 30%.
⑤Anti-classical, electromagnetic shielding and electrical insulation are good.
The most commonly used shell plastics are ABS, HIPS., modified PP and PVC/ABS, of which modified PP is low in price and is replacing HIPS and ABS, only a few high-end shells products use PC, PPO heat-resistant plastics.
3)The Principle of Thermoplastic Elastomer Selection.
It shows the elasticity of rubber at normal temperature, and can be plasticized at high temperature. - Polymeric material, referred to as TPE. The thermoplastic elastomer combines the characteristics of both plastic and rubber, it has both high elasticity of rubber and thermoplasticity of plastic. There are both rubber and plastic segments in the form, copolymerized in blocks, and there is a chemical or physical cross-linking in the molecule. This cross-linking is reversible, and it loses cross-linking at high temperatures. The thermoplastic processing properties of plastics restore cross-linking at room temperature to give them high elasticity of rubber. It is divided into several types:
Vinyl chloride: TPVC
Plastic coloring is mainly divided into two types, one is direct injection molding, and the other is surface painting.
1)Direct injection molding: the color is added in the plastic injection molding granules. This method is more environmentally friendly. Because the physical properties of ABS are relatively stable, the harmful substances has very small amount of volatilization when used at normal temperature, and it will not cause harm to the human body.
2)Surface painting: There are two kinds of paint: PU paint and UV paint. PU paint is mostly used on the vacuum cleaner. If the PU paint is of lower quality, it will easily generate harmful gas. If the manufacturer uses high quality paint, the physical properties are stable with less volatile harmful gas.