A kind of high toughness epoxy resin and its preparation method and application

Abstract

The invention discloses a high-toughness epoxy resin as well as its preparation method and application. Specifically, the present invention introduces a method for preparing the high-molecular-weight epoxy resin in a short period of time. The synthesis reaction is carried out in a solvent-free state, the synthesis reaction speed is fast, and the reaction temperature is low, which is set at 170-185 ° C; the reaction time is short , only 2 to 4 hours, greatly improving production efficiency, and can effectively reduce the formation of gelatinized insoluble matter. The epoxy resin of the invention has the characteristics of high molecular weight and low viscosity, and the prepared coating has fast curing speed, good flexibility of the cured paint film, good butanone wiping resistance and excellent water boiling performance.

Description

technical field [0001] The invention relates to the field of coatings, and relates to a preparation method of a high-molecular-weight epoxy resin as a base material used for improving the performance of metal food can coatings in a short period of time, and an application of the epoxy resin. Background technique [0002] Packaging container materials are generally divided into metal cans, glass jars, and retort bags. Among them, metal containers are widely used because of their beautiful appearance and high-grade characteristics. [0003] Metal packaging cans are generally made of tinplate, aluminum sheets and other materials, but the metal materials will react with food, beverages and other contents, such as reacting with organic acids to dissolve tin, generate hydrogen, or generate brown-black sulfur spots etc., thereby contaminating food and beverages and causing container damage. Therefore, it is necessary to cover a layer of organic protective coating on the can contai...

AI Technical Summary

Problems solved by technology

[0009] (1) The commonly used production process takes 6-9 hours. If a solvent is added, the temperature of the reaction process is lower, so the reaction time is longer, even reaching 10-12 hours, and the weight-average molecular weight Mw of the resin can reach 20,000; The boiling point of the solvent is high to increase the reaction speed and shorten the reaction time, so there will be more solvent remaining in the finished epoxy resin, and the solvent will be released during the granulation and packaging process, polluting the air environment and harming human health

[0010] (2) By increasing the reaction temperature (generally set at 180-200°C) or prolonging the reaction time for production, it is easy to produce gel particles with very high molecular weight, which are insoluble and infusible. If it cannot be filtered out, it will remain on the surface of the coating, affecting its appearance and corrosion resistance

[0011] (3) The molecular weight of epoxy resin increases, the solution viscosity also increases, the viscosity of the coating is high, the surface tension is large, and the wettability to the substrate is poor

Generally, a small amount of 7# epoxy resin with slightly lower molecular weight can be added for adjustment, but the production process is increased

[0012] (4) Generally, the coating made of 9# resin needs to be baked at 200-220°C for 10-20 minutes (adding catalyst), which has high energy consumption and low production efficiency

[0013] (5) After the can coating is cured, the uncured small molecules or solvent residues in the paint film may be dissolved and extracted by the content, thus causing quality problems for food, beverages, etc.

If the baking time is prolonged, the small molecular polymers can be reduced, but over-baking will increase the hardness of the coating, the adhesion will drop sharply, the coating will become discolored and brittle, and the impact resistance will be poor.

Images