	US 11,920,034 B2
	Polyamide composition containing flat glass fibres (B) with improved fatigue resistance
Gilles Robert, Craponne (FR); Tae-Kyun Kim, Gyeonggi-do (KR); Weibing Wang, Lyons (FR); and Franco Speroni, Ceriano Laghetto (IT)
Assigned to BASF SE, Ludwigshafen am Rhein (DE)
Appl. No. 17/287,957
Filed by BASF SE, Ludwigshafen am Rhein (DE)
PCT Filed Oct. 22, 2019, PCT No. PCT/EP2019/078709 § 371(c)(1), (2) Date Apr. 22, 2021, PCT Pub. No. WO2020/083901, PCT Pub. Date Apr. 30, 2020.
Claims priority of application No. 18306379 (EP), filed on Oct. 22, 2018.
Prior Publication US 2021/0371652 A1, Dec. 2, 2021
Int. Cl. C08L 77/02 (2006.01); B29C 45/00 (2006.01); C08K 3/40 (2006.01); C08K 7/14 (2006.01); B29K 77/00 (2006.01); B29K 309/08 (2006.01)

CPC C08L 77/02 (2013.01) [B29C 45/0001 (2013.01); B29C 45/0005 (2013.01); C08K 3/40 (2013.01); C08K 7/14 (2013.01); B29K 2077/00 (2013.01); B29K 2309/08 (2013.01); C08K 2201/004 (2013.01)]

14 Claims

1. A polyamide composition (P) for the production of molded parts, wherein the polyamide composition (P) comprises:

(a) 25 to 85 wt.-%, based on the total weight of the polyamide composition (P), of polyamide (A);

(b) 15 to 75 wt.-%, based on the total weight of the polyamide composition (P), of at least one flat glass fibre (B) with elongated shape having a non-circular cross-sectional area;

(c) 0 to 30 wt.-%, based on the total weight of the polyamide composition (P), of at least one reinforcement agent (C) different from the flat glass fibre (B),

(d) 0 to 30 wt.-%, based on the total weight of the polyamide composition (P), of at least one additive (D);

wherein

the at least one polyamide has a viscosity number (VN), measured according to ISO 307 in a 0.005 g/ml solution in 90 wt.-% formic acid at 25° C., in a range of from 80 to 200 mL/g;

the at least one flat glass fibre (B) as comprised in the polyamide composition (P) is defined by the following parameter:

(i) an aspect ratio of the length of a main cross-sectional axis w to the length of a secondary cross-sectional axis d of the non-circular cross-sectional area of the flat glass fibre (B) is from >3 to 10;

(ii) an average length L_zof the flat glass fibre (B), defined by the following formula (1), has a minimum value of 400 μm and a maximum value of 700 μm:

L_z=Σ_i=1ⁿ(L_i)³n_i/Σ_i=1ⁿ(L_i)²n_i (1),

wherein:

L_iis the length of the largest dimension in one of the spatial directions of a fraction of the flat glass fibre (B) in the polyamide composition (P),

n_iis the number of flat glass fibres (B) having the length L_i,

n is the total number of flat glass fibres (B), and

i is an integer from 1 to ∞; and

(iii) a ratio between an average longest dimension L_n, defined by the following formula (2), of the flat glass fibre (B) and a shortest average dimension d of the flat glass fibre (B) is

L_n=Σ_i=1ⁿL_in_i/Σ_i=1ⁿn_i (2),

wherein:

L_iis the length of the largest dimension in one of the spatial directions of a fraction of the flat glass fibre (B) in the polyamide composition (P),

n_iis the number of flat glass fibres (B) having the length L_i,

n is the total number of flat glass fibres (B),

i is an integer from 1 to ∞, and

d is the length of the shortest dimension in one of the spatial directions of a fraction of the flat glass fibre (B); and

wherein the polyamide composition (P) comprises no other polyamide than PA 6.6.