Preparation method and application of epoxy resin modified polyamide resin and powder coating

Abstract

The invention discloses a preparation method and application of epoxy resin modified polyamide resin and powder coating. The resin is prepared from raw materials containing polyamide resin and bifunctional epoxy resin. A terminal group of the polyamide resin is a carboxyl group, molecular weight of the polyamide resin is 1000-8000 g/mol, the dosage of the epoxy resin is 5-50% of the mass of the polyamide resin, and the mass of monomers having a carbon number of ten or more in polymerized monomers accounts for 50-100% of total monomer mass. The preparation method includes the step that the polyamide resin and the epoxy resin are subjected to melt mixing or homogenate dispersion mixing. By using the epoxy resin modified polyamide resin, the powder coating can be prepared, and a polymer coating layer with high-strength and excellent characteristics can be obtained after baking heat treatment.

Description

technical field [0001] The invention belongs to the technical field of polyamide material preparation methods, in particular to an epoxy resin modified polyamide resin and their applications. Background technique [0002] In recent years, powder coating has become the fastest-growing variety among various coating varieties due to its solvent-free, excellent performance and ease of automatic coating. As a kind of thermoplastic powder coating, polyamide powder coating has been paid attention to and widely used for its unique wear resistance, physical and mechanical properties and durability. Generally, long carbon chain polyamide is the main type, such as nylon 1010, nylon 11, nylon 12. Although its total usage is not large, as a high-end coating, it plays an important role in the fields of coastal equipment protection, chemical industry, coating of food contact and human contact articles, and small parts coating. [0003] However, like most other thermoplastic powder coatin...

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Problems solved by technology

[0003] However, like most other thermoplastic powder coatings, polyamide powder coatings also have obvious disadvantages, for example: first, the resin cannot be pulverized at room temperature by a simple mechanical pulverization method like a thermosetting resin, and generally requires a cryogenic pulverization method Carry out pulverization (CN201210432025.X), pulverization efficiency is relatively low, and energy consumption is also bigger; Or adopt solvent precipitation method to prepare polyamide microsphere (US Patent US20080249237A1), need to use a large amount of solvents, efficiency will be lower, and cannot Continuous production; second, the melting point of thermoplastic polyamide resin is relatively high, under the condition of powder coating baking temperature, the melt viscosity is very high, and the leveling property of the coating film is not good; third, the extreme The density of reactive groups is relatively low, so the adhesion to metal substrates is average, and primers are required in many cases, which increases the difficulty of construction; fourth, the high melt viscosity of long-carbon chain polyamide powder coatings easily leads to the resin’s adhesion to pigments and fillers. The wettability is also relatively poor, the dispersion is not good, and the amount of addition is relatively small

Therefore, based on the above shortcomings, although the long carbon chain polyamide powder coating has good performance, its current application is relatively limited.

[0004] If the preparation performance and fluidity of the powder are improved by reducing the molecular weight of polyamide, the impact strength and toughness of the polyamide coating film sprayed by electrostatic spraying will be significantly reduced due to the reduction of molecular weight, and the performance will inevitably be affected.

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