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OwnerLuz Adriana Gomez Ortiz, Ricardo Hernández Salas +4inventors
InventorsLuz Adriana Gomez Ortiz, Ricardo Hernández Salas, Eduardo Oliveira Cruz, Carlos Alfonso Cruz, Morris Christopher Wills, Charles J. Rand
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The present invention provides fiber cement articles, such as roof tiles having improved impact and hail resistance and methods for making them. The fiber cement articles comprise cement, an optional filler, reinforcing fibers, such as poly(vinyl alcohol) fibers or a mixture of cellulosic and synthetic fibers, one or more core-shell aqueous emulsion polymers having a crosslinked rubbery core with a calculated glass transition temperature (calculated Tg) of from −20 to −140° C., and an at least partially grafted acrylic or vinyl shell polymer having a calculated Tg of from 20 to 170° C., and having a Z-average primary particle size of from 55 to 800 nm, or, preferably, from 140 to 650 nm. The solids weight ratio of the crosslinked rubbery core to the shell of the core-shell aqueous emulsion polymer may range from 85:20 to 97:3.
A fiber cement article having improved impact resistance comprising from 1 to 25 wt. %, based on the total solids weight of the fiber cement article, of one or more core-shell aqueous emulsion polymers having a crosslinked rubbery core with a calculated glass transition temperature (calculated Tg) of from −20 to −140° C., and an at least partially grafted acrylic or vinyl shell polymer having a calculated Tg of from 20 to 170° C., and a Z-average primary particle size of from 55 to 800 nm, cement, and, further wherein, the fiber cement article comprises reinforcing fibers.
Dependencies are inferred from the claim text.