Reactive flame retardants blends for flexible polyurethane foams

#This invention relates to reactive flame retardant blends for flexible polyurethane foams.

#The flexible polyurethane foams that are a part or the invention are well known in the industry. Information on preparation and common reactants can be found in many resources, including the Encyclopedia of Polymer Science and Engineering, Vol. 13, copyright 1988. John Wiley & Sons, Inc. Flexible polyurethane foams are used to make resilient structural materials such as cushioning or padding materials in the furniture and automotive industries. It is known to incorporate tire-retardant compounds into such foam materials to produce combustion modified flexible foam. However, care has to be taken so that adequate fire retardancy can be achieved without adversely affecting the desired physical properties of such foam materials. Increasing concerns over volatile organic compound emission levels and odor have resulted in a desire for incorporating polymeric or reactive flame retardant compounds into flexible polyurethane foam instead of additive flame retardant compounds.

#Polyurethane foam is formed by a reaction between a polyol and diisocyanate. This reaction is highly exothermic.

#The new reactive flame retardant composition of the present invention can be used in combustion modified flexible slabstock polyurethane foams to solve the problem of inconsistent air permeability. This new reactive flame retardant is a two component liquid blend Of (a) at least one brominated aromatic diester diol and (b) at least one epoxy resin, and can optionally contain an additional component, such as (c) at least one hindered phenolic antioxidant, to improve scorch prevention. The amounts of components (a), (b) and (c) used in forming said mixture are such that in a base resin blend of 100 parts, the proportions of (a):(b) are about 98.5:1.5 to about 96.5:3.5, or even about 98:2 to about 97:3; and when component (c) is present, the relative proportion of (c):(a)+(b) is in the range of about 0.1:100 to about 1:100.

#The brominated aromatic diester diol is a diester diol of tetrabromophthalic acid, which is the reaction product of tetrabromophthalic anhydride (TBPA), a C2 to C6 polyhydric aliphatic alcohol (PAA), preferably diethylene glycol, and a substituted or unsubstituted C3 to C8 alkylene oxide (AO), preferably propylene oxide. In one practical embodiment, in which the PAA is diethylene glycol and the AO is propylene oxide, the diester diol has the following formula:

#where n is typically in the range from about 1 to about 5. The synthesis of this material is disclosed in U.S. Provisional Patent Application No. 61/292,988, incorporated by reference herein in its entirety.