Flame retardant and preparation process thereof
Provided are a process for preparing a flame retardant, a flame retardant obtained by the process and use of the flame retardant in a polymer composition.
1. A process for preparing a flame retardant, the process comprising the steps of:
(i) providing a reaction product of a Compound (N) with a Compound (P) in the absence of a catalyst;
(ii) adding an oxidant to the reaction product in (i) and reacting the mixture to obtain the flame retardant;
wherein:
the Compound (N) is a compound according to general formula (I) or general formula (II):
R 1 , R 2 , and R 3 is independently hydrogen, hydroxyl, amino, or mono- or diC 1 -C 8 alkyl amino; or C 1 -C 8 alkyl, C 5 -C 16 cycloalkyl, alkylcycloalkyl, each being optionally substituted by a hydroxyl or a C 1 -C 4 hydroxyalkyl, C 2 -C 8 alkenyl, C 1 -C 8 alkoxyl, acyl, acyloxy, C 6 -C 12 aryl, —OR 1 and —N(R 1 )R 2 ; or is N-alicyclic or N-aromatic, where N-alicyclic denotes cyclic nitrogen containing compounds and N-aromatic denotes nitrogen containing heteroaromatic ring compounds; provided that at least one of R 1 , R 2 , and R 3 is an amino group, or a mono- or diC 1 -C 8 alkyl amino group;
a and q is each independently 1, 2, 3 or 4;
X is an acid selected from the group consisting of phosphoric acid, pyrophosphoric acid, cyanuric acid and a C 6 -C 12 aromatic carboxylic acid;
the Compound (P) is according to general formula (III):
R 4 , R 5 , R 6 and R 7 is independently a C 1 -C 5 hydroxylalkyl;
Y is an anion, n is valence of Y.
2. The process of claim 1 , wherein the Compound (N) is selected from the group consisting of melamine, melamine cyanurate, melamine phosphate compounds, dimelamine phosphate compounds, melamine pyrophosphate compounds, melem, melam, melon, ammeline, ammelide, and a mixture thereof.
3. The process of claim 1 , wherein the compound (N) is melamine.
4. The process of claim 1 , wherein the Compound (P) is according to general formula (IV):
wherein Y is an anion, n is valence of Y.
5. The process of claim 1 , wherein Y is a halide anion, SO 4 2− , NO 3 − , PO 4 3− , H 2 PO 2 − , HPO 3 2− , or RCOOH − wherein R is an alkyl, hydroxyalkyl, alkenyl or hydroxylalkenyl.
6. The process of claim 1 , wherein Y is Cl − , Br − , SO 4 2− , NO 3 − , PO 4 3− , H 2 PO 2 − , or HPO 3 2− .
7. The process of claim 1 , wherein the Compound (P) is bis[tetrakis(hydroxymethyl)phosphonium]sulfate (THPS) or tetrakis(hydroxymethyl)phosphonium Chloride (THPC) or a mixture thereof.
8. The process of claim 1 , wherein the molar ratio of the Compound (N) to the Compound (P) is from 1:5 to 5:1.
9. The process of claim 1 , wherein in the step (ii), the oxidant is selected from H 2 O 2 , oxygen, a pyrosulfite salt, a persulphate salt, a peroxodisulfate salt and an organic peroxide.