Coating knowledge: overview of urea formaldehyde resin

Core tip: urea formaldehyde resins trade name beetle Also known as urea formaldehyde resin, referred to as UF, with an average molecular weight of about 10000 Under the catalysis of acid or alkali, urea and 37% formaldehyde aqueous solution can polycondensate to obtain linear urea powder urea formaldehyde resin aldehyde oligomer In industry, alkali is used as catalyst, reaction temperature is about 95 ℃, and the molar ratio of formaldehyde / urea is 1.5-2.0, so as to ensure the resin can be solidified The first step is to produce one and dimethylmethyl urea, then the hydroxyl group is further condensed with the amino group to get the soluble resin If it is catalyzed by acid, it will lead to gel Product requirement Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Home of coatings: urea formaldehyde resins trade name beetle Also known as urea formaldehyde resin, referred to as UF, with an average molecular weight of about 10000 Under the catalysis of acid or alkali, urea and 37% formaldehyde aqueous solution can polycondensate to obtain linear urea powder urea formaldehyde resin aldehyde oligomer In industry, alkali is used as catalyst, reaction temperature is about 95 ℃, and the molar ratio of formaldehyde / urea is 1.5-2.0, so as to ensure the resin can be solidified The first step is to produce one and dimethylmethyl urea, then the hydroxyl group is further condensed with the amino group to get the soluble resin If it is catalyzed by acid, it will lead to gel The product can only be stored in neutral condition The linear urea formaldehyde resin can be cured at room temperature with ammonium chloride as curing agent The curing temperature of molding powder is 130-160 ℃, and the curing process can be accelerated by promoters such as zinc sulfate, trimethyl phosphate, diethyl oxalate, etc Urea formaldehyde resin is mainly used in the manufacture of molding plastics, daily necessities and electrical parts, as well as board adhesives, paper and fabric pastes, veneers, building decorative boards, etc Because of its light color and easy coloring, products are often rich and magnificent in color Urea formaldehyde resin has low cost, light color, high hardness, oil resistance, mildew resistance, good insulation and temperature resistance, but poor weather and water resistance It is one of the early thermosetting resins In 1924, the British cyanamide company developed and sold products in 1928 In the mid-1930s, the output reached a thousand tons, and in the 1980s, the world's annual output has exceeded 1.5MT The amount of urea formaldehyde resin used to make plastic products only accounts for about 10% of the total output When the molar ratio of formaldehyde and urea is low, the urea formaldehyde resin is mixed with fillers (pulp, wood powder), colorants, lubricants, curing agents, stabilizers (hexamethylenetetramine, ammonium carbonate), plasticizers (urea or thiourea) and other components, and then dried, crushed, milled and screened to obtain the urea formaldehyde compression molding powder The temperature and pressure of urea formaldehyde plastics are 140-150 ℃ and 25-35mpa respectively The pressing time varies with the thickness of products, generally 10-60min Plastic products are mainly electrical lighting equipment and telephone parts Urea formaldehyde resin is generally water-soluble resin, which is easy to cure The cured resin is non-toxic, colorless and light resistant It does not change color in long-term use and does not change color in hot forming Various colorants can be added to prepare products with bright colors Urea formaldehyde resin is hard, scratch resistant, weak acid and alkali resistant, oil and other media It is cheap and has certain toughness, but it is easy to absorb water, so its water resistance and electrical properties are poor, and its heat resistance is not high Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,