Preparation method for environmental protection type polyamide-imide wire enamel

Abstract

The present invention discloses a preparation method for an environment protection type polyamide-imide wire enamel. The preparation method comprises: adopting an ester solvent with a boiling point of more than 150 DEG C as a main solvent; adding the main solvent to a reactor, and stirring; heating to a temperature of 50-60 DEG C, and dissolving; pouring isocyanate and anhydride, controlling a reaction temperature to a range of 80-85 DEG C, and maintain for 1-3 h; heating to a temperature of 120-125 DEG C within 1 h, and maintain for 1-3 h; heating to a temperature of 155-160 DEG C within 1 h, and performing the reaction until a transparent state is achieved; cooling to a temperature of 130-135 DEG C, adding the main solvent, and concurrently and rapidly adding a mixture of a blocking agent and a catalyst, and carrying out thermal insulation for 1-1.5 h at a temperature of 100-115 DEG C; and finally adding a diluent to carry out wire enamel adjustment, wherein a solid content of the wire enamel is adjusted to 36-20%.

Description

technical field [0001] The invention relates to a wire enamel technology, in particular to a preparation method of an environment-friendly polyamide-imide wire enamel. Background technique [0002] Polyamide-imide has outstanding advantages such as high heat resistance and good refrigerant resistance, and is widely used in the production of enameled wires with high heat resistance requirements and high performance, such as composite enameled wires with refrigerant resistance. [0003] However, the polyamide-imide wire enamel produced at present has the following disadvantages at the same time. 1) The cost is high, because its main solvent N-methylpyrrolidone is the highest price among the solvents used in wire enamel. As a solvent, it is used in enameled wire The production process is also converted into heat by catalytic combustion, and the heat obtained after combustion of N-methylpyrrolidone (NMP) is not as good as cresol (combustion heat: NMP=3010kJ / mol, cresol=3706kJ / mo...

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Problems solved by technology

[0003] However, the polyamide-imide wire enamel produced at present has the following disadvantages at the same time. 1) The cost is high, because its main solvent N-methylpyrrolidone is the highest price among the solvents used in wire enamel. As a solvent, it is used in enameled wire The production process is also converted into heat by catalytic combustion, and the heat obtained by burning N-methylpyrrolidone (NMP) is not as good as cresol (heat of combustion: NMP=3010kJ / mol, cresol=3706kJ / mol)

2) High toxicity. Currently, the main solvent N-methylpyrrolidone used in polyamide-imide wire enamel is toxic, and its use is restricted in the chemical convention

3) Insufficiency in the enamelling process, because polyamideimide paint uses N-methylpyrrolidone as the main solvent, N-methylpyrrolidone is a strong polar solvent, easy to absorb moisture, and the enameled wire paint is exposed in the paint tank It absorbs moisture in the air, especially under the process conditions of felt painting. After absorbing moisture, resin will precipitate in the felt, blocking the flow of paint in the felt, and affecting the painting of enameled wires. In this way, new felts must be replaced in time. In wet weather, it is often necessary to change it every two or three days, which not only affects the work efficiency, but also increases the pollution to the environment

4) It is incompatible with other types of enameled wires. The current polyamide-imide enameled wire enamel cannot be mixed with polyesterimide and other enameled wire enameled with cresol as the main solvent. If it is accidentally mixed, it will be cloudy and precipitated immediately. It is very inconvenient to the enamelling process. For example, the cleaning of the enamelling machine should be particularly clean when changing the production type, which will produce a large amount of cleaning solvent; special care should be taken when producing composite enameled wires, and special attention should be paid to the top coat and primer. mix

[0004] The current polyamide-imide wire enamel not only has its irreplaceable outstanding advantages, but also has the disadvantages of being limited and inconvenient to use. In order to meet the needs of the continuous development of modern society, especially for environmental protection, it must Change the main solvent of polyamideimide wire enamel, and replace N-methylpyrrolidone with other main solvents

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