FLAME RETARDANT POLYAMIDE COMPOSITION

1 . Flame retardant polyamide composition comprising

(A) a semi-crystalline semi-aromatic polyamide having a melting temperature (TmA);

(B) a semi-crystalline aliphatic polyamide having a melting temperature (TmB); and

(C) a halogen free flame retardant system comprising a metal salt of a phosphinic acid and/or a diphosphinic acid

wherein

the weight ratio of (A):(B) is in the range between 50:50 and 75:25;

(A) has a number average molecular weight (Mn-A) in the range between 7,500 and 30,000 g/mol;

(B) has a number average molecular weight (Mn-B) in the range between 7,500 and 50,000 g/mol;

TmA is higher than TmB.

2 . Flame retardant polyamide composition according to claim 1 , wherein Mn-A is in the range of 10,000-25,000 g/mol, and/or wherein Mn-B in the range of 10,000-40,000 g/mol.

3 . Flame retardant polyamide composition according to claim 1 , wherein Tm-A is in the range of 290-350° C., and/or wherein Tm-B is in the range of 250-300° C.

4 . Flame retardant polyamide composition according to claim 1 , wherein the weight ratio of (A):(B) is in the range of 55:45 72.5:27.5.

5 . Composition according to claim 1 , wherein (A) and (B) have a negative X parameter, the X parameter being calculated for (A) and (B) by applying the method according to T. S. Ellis in Macromolecules 1991,24, 3845-3852 and using the following formula

X

blend

=

[

(

1

-

x

)



(

y

-

x

)

+

z



(

x

-

y

)

]

*



7.982

+

(

1

-

y

-

z

)



(

1

-

x

-

z

)

*



7.46

-

(

1

-

y

-

z

)



(

x

-

y

)

*



0.288

wherein x and 1-x represent the relative amounts of methylene and amide phenyl repeat units in (A), and y, z and 1-y-z represent the relative amounts of methylene, amide and phenyl repeat units in (B).

6 . Flame retardant polyamide composition according to claim 1 , wherein the flame retardant system (C) comprises an aluminium (di)phosphinate.

7 . Flame retardant polyamide composition according to claim 1 , wherein (C) is present in an amount of at least 5 wt. % and at most 30 wt. %, relative to the total weight of the composition.

8 . Composition according to claim 1 , wherein the composition comprises at most 1 wt. % ZnBorate.

9 . Flame retardant polyamide composition according to claim 1 , wherein the composition comprises inorganic fillers and/or fibrous reinforcement agents (D) in a total amount of at least 5 wt. %, relative to the total weight of the composition.

10 . Flame retardant polyamide composition according to claim 1 , comprising 5-25 wt. % of flame retardant (C), and 5-60 wt. % of glass or carbon fibre reinforcement, wherein the wt. % are relative to the total weight of the composition.

11 . Process for the production of moulded parts from a flame retardant polyamide composition by injection moulding, comprising a step wherein the composition is heated in an injection moulding machine to form a polymer melt, characterized in that the composition is a the flame retardant polyamide composition according to claim 1 comprising a semi-crystalline semi-aromatic polyamide (A) having a melting temperature (TmA); and a semi-crystalline aliphatic polyamide (B) having a melting temperature (TmB); and wherein the melt is heated to a temperature of at most 10° C. above TmA.

12 . Process according to claim 11 , wherein the polymer melt is injected into a mould with a mould temperature of at least 100° C., preferably in the range of 110 150° C.

13 . Article made from a composition according to claim 1 .

14 . Article according to claim 13 , being a plastic part for a connector.

15 . Article according to claim 13 , being a housing or a stiffener frame for an electronic device.