POLYESTER COMPOSITIONS AND CORRESPONDING ARTICLES
Described herein are polyester compositions including a semi-aromatic, semi-crystalline polyester, a polyolefin and a glass fiber having a low D k and low D f (“low D k /D f glass fiber”). The concentrations of the semi-crystalline polyester and polyolefin are selected such that the polyester weight ratio is from 70% to 95%. It was surprisingly found that when the polyester weight ratio was in the aforementioned range, the polyester compositions had an excellent balance of dielectric properties (D k and D f ) and mechanical properties (e.g., notched impact strength). It was also surprisingly found that when polyester composition further included high D k /D f glass fibers, the balance of dielectric and mechanical properties was still further improved when the polyester weight ratio was from 75% to 93%. Due at least in part to the excellent balance of dielectric and mechanical properties, the polyester compositions can be desirably incorporated into mobile electronic device components.
1 . A polyester composition comprising:
a semi-aromatic, semi-crystalline polyester;
a polyolefin comprising at least 80 mol % of a recurring unit (R PO ) including at least 4 carbons, the mol % being relative to the total number of recurring units in the polyolefin, the recurring unit (R PO ) being represented by the following formula:
wherein R 5 to R 8 are independently selected from the group consisting of a hydrogen and a C 1 -C 10 alkyl group;
a glass fiber having, as measured according to ASTM D150 at 1 MHz, a D k of no more than 5.5 and a D f of no more than 0.002; and
a polyester weight ratio of from 70% to 95%;
wherein
the polyester weight ratio is given by the formula:
100
×
W
PE
W
PO
+
W
PE
,
and
W PE and W PO are, respectively, the weights of the semi-aromatic, semi-crystalline polyester and the polyolefin in the polyester composition.
2 . The polyester composition of claim 1 , wherein the semi-aromatic, semi-crystalline polyester comprises a recurring unit R PE that is represented by the following formula:
wherein T is a C 1 -C 18 alkyl and Ar is an aryl.
3 . The polyester composition of claim 2 , wherein recurring unit R PE is represented by either one of the following formulae:
wherein R 1 to R 4 , at each location, are independently selected from the group consisting of a hydrogen and a C 1 -C 12 alkyl, and wherein q, n and m are independently selected integers from 1 to 12.
4 . The polyester composition of claim 1 , wherein the semi-aromatic, semi-crystalline polyester is selected from the group consisting of polycyclohexylenedimethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and polybutylene naphthalate.
5 . The polyester composition of claim 1 , wherein R 6 to R 8 are hydrogen.
6 . The polyester composition of claim 3 , wherein R 3 is a C 3 to C 10 alkyl.
7 . The polyester composition of claim 1 , wherein the polyolefin is selected from the group consisting of poly(4-methyl-1-pentene), poly(1-butene), and poly(1-pentene) and poly(1-hexene).
8 . The polyester composition of claim 1 , wherein the polyester weight ratio is from 75% to 95%.
9 . The polyester composition of claim 1 , further comprising a high D k /D f glass fiber.
10 . The polyester composition of claim 9 , wherein the polyester weight ratio is from 75% to 93%.
11 . The polyester composition of claim 1 , wherein the polyester composition comprises, as measured according to ASTM D150 at 1 kHz, a D k of no more than 3.5 and a D f of no more than 0.003.
12 . The polyester composition of claim 1 , wherein the polyester composition comprises, as measured according to ASTM D150 at 1 MHz, a D k of no more than 3.4 and a D f of no more than 0.03.
13 . The polyester composition of claim 1 , wherein the polyester composition comprises a notched impact strength of at least 80 J/m, as measured according to ASTM D256.
14 . A mobile electronic device component comprising the polyester composition of claim 1 .
15 . The mobile electronic device component of claim 14 , wherein the mobile electronic device is selected from the group consisting of a mobile phone, a personal digital assistant, a laptop computer, a tablet computer, a wearable computing device, a camera, a portable audio player, a portable radio, global position system receivers, and portable game consoles.
16 . The polyester composition of claim 1 , wherein the recurring unit (R PO ) of the polyolefin includes at least 5 carbon atoms.
17 . The polyester composition of claim 7 , wherein the polyolefin is poly(4-methyl-1-pentene).