US 12,168,729 B2
Flame-retardant epoxy composition and method of using the same
Leonard MacAdams, Woolwich Township, NJ (US); and Dalip K. Kohli, Churchville, MD (US)
Assigned to CYTEC INDUSTRIES INC., Princeton, NJ (US)
Appl. No. 17/414,132
Filed by CYTEC INDUSTRIES INC., Princeton, NJ (US)
PCT Filed Dec. 17, 2019, PCT No. PCT/US2019/066963
§ 371(c)(1), (2) Date Jun. 15, 2021,
PCT Pub. No. WO2020/131946, PCT Pub. Date Jun. 25, 2020.
Claims priority of provisional application 62/781,190, filed on Dec. 18, 2018.
Prior Publication US 2022/0081551 A1, Mar. 17, 2022
Int. Cl. C08L 63/00 (2006.01); B32B 3/12 (2006.01); C09D 163/00 (2006.01); C09K 21/04 (2006.01)
CPC C08L 63/00 (2013.01) [B32B 3/12 (2013.01); C09D 163/00 (2013.01); C09K 21/04 (2013.01); B32B 2250/40 (2013.01); B32B 2255/26 (2013.01); B32B 2305/024 (2013.01); C08L 2201/02 (2013.01); C08L 2205/035 (2013.01)] 14 Claims
 
1. A method for filling voids in a honeycomb sandwich panel, comprising:
providing a honeycomb sandwich panel comprising a honeycomb core disposed between two sheets of composite materials, said honeycomb core comprising one or more voids to be filled with a potting composition;
introducing a potting composition into the one or more voids of the honeycomb core;
curing the honeycomb sandwich panel with the potting composition,
wherein the potting composition is a halogen-free, curable epoxy composition comprising:
a) an epoxy component comprising at least one epoxide compound having an epoxide functionality of at least 1;
b) at least one curative;
c) at least one latent curing accelerator;
d) a toughening component comprising nano-sized core shell rubber (CSR) particles having particle size of less than 1 micron;
e) a fire-retardant component that is halogen-free; and
f) hollow microspheres for reducing the density of the composition;
wherein the latent curing accelerator is selected from amine-epoxy adducts, amine-ureido adducts, and amine-urethane adducts, which are insoluble in the epoxy component at room temperature in the range of 21° C. to 25° C.,
wherein the fire-retardant component comprises a mixture of: (i) at least one polyphosphate; (ii) at least one metal borate; and (iii) at least one compound selected from alkaline earth metal hydroxides and aluminum hydroxides, and
wherein, after curing, the cured potting composition possesses a density of less than 0.8 g/cm3.