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 polyester resin as the hydroxyl component is firstly synthesized with terephthalic acid diol or amidoimide diol, and then polymerized with polybasic acid and polyol, semi-finished terephthalic acid diol or amidoimide The final index of imine dihydric alcohol is unstable, which has an impact on the next step reaction; in the synthesis of blocked isocyanate components, dimethylformamide (DMF) is used as a solvent, which is easily mixed with aromatic compounds in the synthesis of blocked isocyanate components. Diisocyanate TDI and MDI react to form by-products, and it is difficult to realize the structure of the formula design; in addition, from the enameled wire test data disclosed in the patent, the thickness of the painted film is already ultra-thick compared to the wire diameter. The ultra-thick paint film formed by polyurethane wire enamel has good salt water pinhole resistance. Therefore, the salt water pinhole performance achieved by it does not indicate that the polyurethane wire enamel provided by this patent application itself has this property. a characteristic