Paint for H grade polyurethane enamelled wire with good saline water needle performace capable of directing welding at low temp.

Abstract

The invention relates to an H-grade wire coating enamel that has good salt water pinhole performance and can be directly welded at low temperature, containing hydroxyl component, sealed isocyanate component and solvent, where its hydroxyl component has an acid value less than 2, a hydroxyl value of 150-300, and number-average molecular weight of 1500-5000, and as synthesized, the raw materials has at least m-phthalic acid, p-phthalic acid, adilic acid, glycerin and a kind of dibasic alcohol in the weight ratio of 1 to (0.2-2) to (0.2-0.5) to (0.5-3) to (0.5-1.5); and its sealed isocyanate component is partially added of MDI by mixed polyalcohol that at least has a dibasic alcohol and a tribasic alcohol; in the paint base, the equivalent ratio of isocyanate base to OH is (0.9-1.2) : 1, and it reaches H-grade and has good salt water pinhole property of paint film, tin daubing temperature less than or equal to 375 deg.C.

Description

technical field [0001] The invention relates to an H-level polyurethane wire enamel with good salt water pinhole performance and low-temperature direct welding. Background technique [0002] Enameled wire enamel mainly forms a continuous and dense paint film on the outer layer of various types of wire diameters (round wire, flat wire) bare copper wire, alloy wire and glass wire by dip coating, so that a good insulation layer is formed between the wires in the winding. to prevent the flow of current. Polyurethane wire enamel is widely used in low-current electrical products such as precision coils, motors, instruments, and household appliances due to its unique excellent properties such as low dielectric loss, direct solderability, and easy dyeing. With the development of the electrical industry, small and medium-sized motor insulation products tend to have high withstand voltage, large capacity and miniaturization, and the miniaturization of motors leads to an increase in o...

AI Technical Summary

Problems solved by technology

The synthesis of polyester resin as a hydroxyl component adopts a two-step synthesis method that first synthesizes terephthalic acid diol or amidoimide diol, and then polymerizes with polybasic acid and polyol. The disadvantage of this method is that the process The control is more complicated, and the final index of the semi-finished terephthalic acid diol or amidoimide diol is unstable, which has an impact on the next reaction; in the synthesis of blocked isocyanate components, dimethylformamide (DMF) is used as a solvent , the solvent is easy to react with aromatic diisocyanate TDI and MDI to form by-products during the synthesis of the blocked isocyanate component, and it is difficult to realize the structure of the formula design; in addition, from the detection data of the enameled wire disclosed in the patent, relative to the wire diameter , the thickness of the painted film is ultra-thick paint film, and the ultra-thick paint film formed by the existing polyurethane wire enamel has good salt water pinhole resistance. Therefore, the salt water pinhole performance achieved by it does not indicate It is the characteristic of the polyurethane wire enamel provided by the patent application itself