Preparation Of Alkali-resistant Core-shell Emulsion Polymers For Fiberglass Mesh

More and more fiberglass mesh were applied in improving the strength of cement product in architecture. It was necessary that the fiberglass mesh had good strength and alkali resistance. By changing the chemical dosage of fiberglass mesh, the alkali resistance could be enhanced, but it made the cost too high. An effective method to enhance the alkali resistance was improving the property of the emulsion binder used in fiberglass mesh. The fiberglass mesh also was necessary to have good properties such as softness and tacky resistance. The conventional emulsion coating film was soft but tacky and easy corroding, or adhesive resistant but hard and easy corroding. In this paper, an alkali resistant emulsion binder was prepared by core-shell polymerization. And several crosslinking agent was used to correct these shortcomings in conventional emulsion. Results were as follows: 1. A coating binder was prepared by core-shell polymerization and an organosilicon coupler was copolymerized in it. The emulsion coating had good properties such as softness , adhesive resistance, high strength, alkali resistance and was satisfied with the property of product. 2. The performance of the coating binder is mainly influenced by the Tg of core polymer and shell polymer, the ratio of core polymer to shell polymer, the dosage of NMA, the dosage of KH-570. The best technology conditions were as follows: Tg of core polymer -45℃, Tg of shell polymer 20℃, the ratio of shell polymer to core polymer 5/4, dosage of NMA about 3%, dosage of KH-570 4%. 3. It was found that 2.0% A, 3.0%B, 2.0% calcium acetate monohydrate could obviously improve the strength and alkali resistance of the coated fiberglass mesh. Although glyoxal could improve the strength and alkali resistance of the coated fiberglass mesh, it could make the coating yellow and be limited in use. Urea, diethylenetriamine were poor in increasing the strength and alkali resistance of the coated fiberglass mesh. Melamine aldehyde could enhance the strength and alkali resistance of the coated fiberglass mesh, but when the dosage was 3.0%, the emulsion would be agglomerated. The crosslinking rate was also explored. 4.By DSC, the polymer was found that two phase were in it, and the Tg of shell polymer was higher than the calculated data because of copolymerizating with KH-570. Distributing of emulsion particles diameter was wide and the shape of latex particles was irregular from TEM. Si-O bond was found from IR spectrum and it proved that organosilicon coupler copolymerized with acrylate polymer.