Novel efficient DOPO‐based flame‐retardants for PWB relevant epoxy resins with high glass transition temperatures

Abstract

Novel derivatives of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) were obtained by a simple synthetic route and incorporated in epoxy resins, consisting of epoxy novolac (DEN 438), dicyandiamide (DICY), and fenuron. The thermal and fire‐retardant properties of DICY‐cured DEN 438 epoxy samples containing the novel DOPO‐based additives were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the UL 94 test. The obtained results were compared to those of specimens containing commercially available phosphates as flame‐retardants. UL 94 tests showed that nitrogen‐containing substituents at the phosphorus atom increase the fire‐retardant efficiency of DOPO‐based additives. Two nitrogen‐substituted DOPO derivatives 4,4′‐Diaminodiphenylmethane (DDM)‐(DOP)2 and DDM‐(DOP)2‐S were found to be very powerful fire‐retardants in DICY‐cured DEN 438 epoxy resins. The V0 rating was achieved at approximately 1% phosphorus in the resin and the glass transition temperature (Tg) was maintained at the high level of the pure DEN 438/DICY epoxy material (Tg = 180–185°C). These novel DOPO derivatives are the first non‐reactive additives having no influence on the Tg of the epoxy material. They not only surpass the capabilities of the other additives used in this work, but also those of all commercially available flame‐retardants for epoxy resins. Therefore, DDM‐(DOP)2 and DDM‐(DOP)2‐S are expected to be qualified for high‐Tg resins commonly used in printed wiring boards (PWB) for high‐performance applications. Copyright © 2008 John Wiley & Sons, Ltd.

Establishment of a highly efficient flame-retardant system for rigid polyurethane foams based on bi-phase flame-retardant actions

“…HQ was originally adapted for epoxy thermosets and exhibits prominent ame-retardant properties in the gas phase. [13][14][15] In addition, HQ can produce active POc radicals during its decomposition, which are capable of reacting with Hc and OHc radicals during the combustion process of the matrix to decrease heat release, prevent further oxidation and consequently suppress ame propagation. 16,17 Besides, the incorporation of HQ into polyurethane can improve the ame retardancy without changing the structure of the matrix, and there is no long-term migration phenomenon.…”

Synthesis of a Novel Phosphorus-containing Flame Retardant for Epoxy Resins

“…The result can be attributed to the fact that the SPD-BS forms a carbonaceous char during combustion, which acts as a physical barrier to insulate heat from the flame and to retard the diffusion of combustible gases, thus improving the flame-retardant properties. 3,6,17,18 This result also indicated that incorporating SPD-BS is very effective in improving the flame retardancy of epoxy resins.…”

Synthesis and reactivity of 6-mercapto-6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide

“…[1][2][3][4][5] Our group is interested in using the versatility of the phosphorus atom to rationally design organophosphorus compounds that could act as flame retardants. [6][7][8][9] 6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (a) is a commercially available flame retardant. To broaden its scope of application, novel derivatives of (a) with tailored chemical structures are synthesized in our working group.…”