Polyethylene glycol melamine modification
CN" face="宋体" size="3">This method is mainly used in the production of post-formed decorative laminates. The post-formed sheet requires a good bend after curingThe performance of the curve, that is, the good flexibility, can be hot pressed again without cracking or brittle when the edge banding and curved veneer decoration
Broken. This resin formula is: melamine
1 mole; formaldehyde 1 . 5 to 2 moles, polyethylene glycol (molecular weight in 200 ~1000
) 5 to 15% (the weight ratio of melamine-formaldehyde solids in aqueous solution), plus the amount of water. In the ratio, if the amount of polyethylene glycol is less than 1 %, the post formability is poor. If it is more than 45 %, the clarity, water resistance and toughness of the resin are damaged. Polyethylene glycol is added during the reaction of melamine with formaldehyde (before and after reflux) at a temperature of 80 to 90 °C. At this point, polyethylene glycol can participate in the chemical reaction. Subsequently, a solvent (methanol) pH adjuster (tetraamine carbonate), a 20 % internal plasticizer (toluene phosphate, etc.) are added. The lower molar ratio of melamine to formaldehyde in the formulation is to reduce the formation of branches of the resin, reduce the degree of crosslinking after hot pressing and cure, and improve the toughness of the sheet. Before impregnation, adjust the resin concentration so that the solid content (containing polyethylene glycol) is 40 to 60 %. At the same time, 1 % release agent (ethyl phosphate and alkyl phosphate) and potential catalyst (aluminum trichloride, magnesium nickel, etc.) are added in an amount of 0.1 to 0.2% by weight of the solid resin . The low-grade decorative laminate is impregnated with this resin, and the bending radius can be as small as 6 mm after the molding, and the temperature only needs to be118
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