Dispensing needle has excellent electrical cutoff functionDate: 2015-09-16
Dispensing needles have excellent electrical cut-off edge function, and their films are one of the larger dielectric losses of various plastic films. Therefore, as high-voltage materials, their corona resistance is poor. Electrical breakdown strength reaches 4500V / mil at 25 ℃ and 60Hz. Temperature has little effect on electrical function, but it is not as good as polystyrene film. At higher temperatures, it can withstand high concentrations of hydrofluoric acid, phosphoric acid, acetic acid, and oxalic acid, but hydrochloric acid, sulfuric acid, and nitric acid can cause it to be destroyed at different levels. Strong bases, especially bases at high temperatures, can cause the appearance of hydrolysis, and the effect of ammonia is more fierce. After being affected by ammonia, the ester chain is broken due to the amidation of the ester chain, and this effect is obvious even at room temperature. It is resistant to ethyl acetate, methyl ethyl ketone, xylene, naphtha, ethylene glycol methyl ether, methanol, and acetic acid. It is not corroded at room temperature or near its boiling point, but can be dissolved in the inclusion liquid of o-chlorophenol, tetrachloroethane, cresol or an excess of nitrobenzene. Emulsifiers can be selected according to the following criteria: ① The HLB value of the selected emulsifier should match the emulsion polymerization system to be performed; ② The triple point of the ionic emulsifier selected should be lower than the reaction temperature; ③ The selected emulsifier The cloud point of non-ionic emulsifiers should be higher than the reaction temperature: ④ For ionic emulsifiers, the larger the masking area as of an emulsifier molecule, the smaller the surface charge density of the latex particles and the more constant the emulsion. Use as small an emulsifier as possible; for nonionic emulsifiers, the greater the as. The stronger the hydration effect, the stronger the constant effect on the emulsion, so an emulsifier with a large as should be used; ⑤ an emulsifier with a critical micelle concentration as small as possible; ⑥ an emulsifier with a large solubilization should be used; ⑦ ion type Emulsifiers and non-ionic emulsifiers have a synergistic effect, that is, the combined use of the two is better than the use of each alone; ⑧ choose an emulsifier similar to the monomer chemical structure can achieve better emulsification results; 较大 more hydrophilic and Emulsifiers with greater lipophilicity have better emulsification results when used in combination; ⑩ The selected emulsifier should not disturb the polymerization reaction; ⑥ When selecting an emulsifier, consider the production process and the use of polymer emulsions, for example, some Although the emulsifier has good emulsification results, the foam is severe under the premise of production and should not be used. For the production of composition rubber, it should be used to make the emulsion system unchanged during the polymerization process, and easy to use during the post-treatment process. Emulsifier from rubber agglutination; ⑩Emulsifier selected should be used in a wide range of sources, domestically, and at a low price.