A kind of preparation method of melamine resin
A technology of melamine resin and melamine, applied in the field of polymer material chemical industry, can solve the problems of complex device preparation process, short shelf life, poor toughness, etc., and achieve the effects of enhancing thermal processing properties, stable product performance and stable composition
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Embodiment 1
[0010] Embodiment 1: 1) 37% formaldehyde, melamine, hexamethylenetetramine are added to the reactor for reaction to obtain melamine formaldehyde resin (prepolymer); the reaction time is 70-75 minutes, and the prepolymerization reaction temperature is controlled to be 100 ℃. The molar weight of formaldehyde feeding is twice that of melamine, and the feeding amount of hexamethylenetetramine is 6% of the melamine quality; the pH value is 8-8.5, 2) adding polyethylene glycol to carry out polycondensation reaction, adding hydrochloric acid to control the pH value is 5-6, the quality of polyethylene glycol is 50% of the mass of melamine, and the molecular weight of polyethylene glycol is about 1000; the polycondensation temperature is controlled at 45-55°C, and the polycondensation time is 80-100min; the pH value is controlled at 5-6 Obtain composite melamine formaldehyde resin; 3) the resin that obtains in step 2) is dropped into kneader, and in kneader, add and adopt short cotton ...
Embodiment 2
[0013] Embodiment 2: 1) 37% formaldehyde aqueous solution, melamine, add reactor and carry out prepolymerization reaction under stirring condition, the mol ratio of melamine and formaldehyde is 1:3, control pH value (by adding hexamethylenetetramine and ) is 8.5, the prepolymerization temperature is controlled at 85°C, and the prepolymerization time is 120min; the quality of hexamethylenetetramine is 10% of the quality of melamine; -6, the quality of polyethylene glycol is 40-60% of the quality of melamine, wherein the molecular weight of polyethylene glycol is 800-1500; the polycondensation temperature is controlled at 45-55°C, and the polycondensation time is 80-100min; composite melamine formaldehyde resin is obtained ; 3) using short cotton fibers and impregnated with an aqueous emulsion acrylic resin, adding inorganic fillers, kneading with the composite melamine-formaldehyde resin obtained in 2) in a kneader (heating temperature 75-85 ° C) to obtain a thick slurry; The a...
Embodiment 3
[0015] Embodiment 3: with embodiment 1-3), then material adopts high-speed kneader mixing, and the rotor of high-speed continuous kneader has two feedings, two feeding sections, two kneading sections (heating temperature 95- 100°C), the upper opening of the second feeding section is specially used for dehumidification, and feeds to the hole in the middle of the rotor through the screw feeding device arranged vertically with the rotor. The use of secondary feeding expands the range of materials processed by the mixer. It can mix and process two materials with different melting temperatures or a large difference, and can also mix materials containing high volatile components. The mixing degree of materials is controlled by two adjustment gates at the end of the front and rear mixing sections. The number of times the material is dispersed and distributed in the mixing chamber will increase until it reaches a certain degree of mixing before it can flow to the next working section ...
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