Coating knowledge: modification of urea formaldehyde resin

It is suggested that urea formaldehyde resin should be modified to improve its performance and expand its application because of its disadvantages such as poor initial viscosity, large shrinkage, high brittleness, water resistance, easy aging, formaldehyde emission, formaldehyde emission from curing and environmental pollution The modification methods are listed as follows: 1 To improve the initial viscosity and improve the initial viscosity of urea formaldehyde resin, polyvinyl alcohol, polyethylene glycol, hydroxymethylcellulose and other modifiers can be added, but the price of these substances is higher, so starch can be selected, especially starch can be added at the beginning of urea formaldehyde resin synthesis, with better effect In the process of synthesis, starch may be hydrolyzed to form various dextrins, etc due to starch Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Home of coatings: due to the disadvantages of urea formaldehyde resin, such as poor initial viscosity, large shrinkage, brittleness, water resistance, easy aging, formaldehyde emission, formaldehyde emission from curing, environmental pollution and health damage, it must be modified to improve performance and expand application The modification methods are listed as follows: 1 To improve the initial viscosity and improve the initial viscosity of urea formaldehyde resin, polyvinyl alcohol, polyethylene glycol, hydroxymethylcellulose and other modifiers can be added, but the price of these substances is higher, so starch can be selected, especially starch can be added at the beginning of urea formaldehyde resin synthesis, with better effect In the process of synthesis, starch may be hydrolyzed to form various dextrins, etc due to the large relative molecular weight of starch, the viscosity of starch after dissolution is also very large The urea formaldehyde resin with high viscosity can be prepared by adding a small amount of starch At the same time, the hydroxyl group, hydroxymethyl group and aldehyde group on the starch molecular chain may participate in the synthesis of urea formaldehyde resin, which not only improves the initial viscosity, but also improves the bonding strength and storage stability 2 It is easy to produce cracks and internal stress in the adhesive layer, which leads to the decrease of viscosity and strength In order to reduce the shrinkage of urea formaldehyde resin during curing, some fillers, such as flour, starch, blood powder, a-cellulose powder, wood powder, bean powder, etc., are usually added to the resin solution 3, reduce brittleness, in order to reduce brittleness and improve toughness, polyvinyl alcohol, polyvinyl formal solution, polyvinyl acetate emulsion, VAE solution can be added, and the initial viscosity and aging resistance can also be improved 4 In the synthesis of urea formaldehyde resin, adding a small amount of melamine, phenol, Resorcinol, alkylamine, glycoaldehyde, etc can effectively improve the water resistance of urea formaldehyde resin Adding aluminum sulfate and aluminum phosphate as crosslinking agent can also improve water resistance obviously Adding wood powder, flour, soybean powder, iron oxide, expansive soil and other fillers can also improve water resistance The urea formaldehyde resin was modified by phenol The benzene ring structure was introduced into the resin to block the water absorption group of the resin, which improved the water resistance and aging resistance of the resin Resorcinol or melamine can also be added to the curing agent, and acrylic copolymer emulsion can be blended with urea formaldehyde resin to improve water resistance 5 To improve the bonding strength, multi-component composite additives such as polyvinyl alcohol and phenol can improve the brittleness, water resistance and bonding strength The shear strength of the UF resin is more than 10 times of that of the original UF resin, and the water resistance and boiling resistance are greatly improved The properties of UF resin can be improved obviously by adding modifier according to different requirements Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news 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