POLYMER COMPOSITION COMPRISING CARBON BLACK AND SHAPED OBJECTS MADE THEREOF

Abstract

A polymer composition containing 0.1-0.6 wt. % nigrosine and 0.01-0.1 wt. % carbon black and 15-25 wt % flame retardant system and wherein the polymer composition contains polybutylene terephthalate (PBT). The invention also relates to a shaped object for use in electrical applications, comprising the composition, preferably a terminal block or a relay.

Claims

1. A polymer composition wherein the polymer composition contains: 0.01-0.1 wt % carbon black; 0.1-0.6 wt % nigrosine; 15-25 wt % flame retardant system; and wherein the polymer composition contains polybutylene terephthalate (PBT).

2. A polymer composition according to claim 1, wherein the L value of the composition is less than 32, as measured according to ISO 7724-1-2-3.

3. A polymer composition according to claim 1, wherein the composition has a Comparative Tracking Index (CTI) of at least 300 V as measured according to IEC standard 60112, preferably at least 350 V, more preferably at least 400 V and most preferred at least 500 V.

4. A polymer composition according to claim 1, wherein the polymer composition contains 0.2-0.55 wt. % nigrosine.

5. A polymer composition according to claim 1, wherein the polymer composition contains 0.3-0.5 wt. % nigrosine.

6. A polymer composition according to claim 1, wherein the polymer composition contains 0.03-0.8 wt. % carbon black.

7. A polymer composition according to claim 1, wherein the flame retardant system is chosen from the group consisting of metal phosphinates, nitrogen containing and nitrogen/phosphor containing flame retardants and combinations thereof wherein the metal phosphinate is a metal of a phosphinic acid of the formula
[R.sup.1R.sup.2P(O)O].sup..sub.mM.sup.m+(formula I) and/or a diphosphinic acid of the formula
[O(O)PR.sup.1R.sup.3PR.sup.2(O)O].sup.2.sub.nM.sub.x.sup.m+(formula II), and/or a polymer thereof, wherein R.sup.1 and R.sup.2 are equal or different substituents chosen from the group consisting of hydrogen, linear, branched and cyclic C1-C6 aliphatic groups, and aromatic groups, R.sup.3 is chosen from the group consisting of linear, branched and cyclic C1-C10 aliphatic groups and C6-C10 aromatic and aliphatic-aromatic groups, M is a metal chosen from the group consisting of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, and K, and m, n and x are equal or different integers in the range of 1-4.

8. A polymer composition according to claim 7, wherein the metal phosphinate comprises a hypophosphate and/or a C.sub.1-C.sub.2 dialkylphosphinate and the nitrogen containing and nitrogen/phosphor containing flame retardant is chosen from the group consisting of benzoguanamine, tris(hydroxyethyl)isocyanurate, allantoine, glycouril, melamine, melamine cyanurate, dicyandiamide, guanidine and carbodiimide, and derivatives thereof.

9. A polymer composition according to claim 1, wherein polymer composition contains an impact modifier.

10. A shaped object for use in electrical applications, comprising the composition of claim 1.

11. Shaped object according to claim 10, wherein the shaped object is a terminal block or a relay.

Description

EXAMPLES

Materials Used

[0043] Arnite T04 201, a PBT, delivered by DSM in the Netherlands. [0044] ICL-F2400-Brominated epoxy polymer, delivered by ICL in the Netherlands. [0045] Sb2O3, Antimony trioxide master batch, comprising 50 wt. % antimony trioxide, delivered by Campine in Belgium. [0046] Dupont Elvaloy AC 2615 an impact modifier delivered by Dupont. [0047] Arkema Lotader AX 8900 an impact modifier delivered by Arkema. [0048] Eurotard AD-70, anti-dripping agent, delivered by European Additives in Germany. [0049] Nigrosin MB deliverd Collids, UK [0050] Carbon black delivered by Cabot.

Preparation of PBT Composition by Compounding

[0051] The polymer compositions were prepared on a ZE40A UTX twin-screw extruder from Berstorff.

[0052] The barrel temperature was set at 260-300 C., the screw speed was 300 RPM and the yield was 180 kg/hour. Components such as PET, nucleating agent and mould release agent, and colorants were dosed to the hopper as a pre-blend. The titanium dioxide was introduced via a side-feeder into the polymer melt. Extruded strands were cooled in water and granulated.

Preparation of Test Specimens by Injection Moulding

[0053] Plaques for color measurements with dimension 80803 mm have been injection moulded from pre-dried (4 hours at 90 C. under vacuum with nitrogen flow) granulate on an Engel 75 injection moulding machine with 25 mm diameter barrier screw. A nozzle with a length of 60 mm was used to inject the material into a mould with high gloss inserts (With ISO 4287 roughness parameter NO, hand polished).

Methods Used

CTI

[0054] The CTI was determined according to the testing method is specified in IEC standard 60112. To measure the tracking, 50 drops of 0.1% ammonium chloride solution are dropped on the material at 20 C., and the voltage measured for a 3 mm plaques.

Colour Measurements

[0055] The colour co-ordinates L*a*b* have been determined with the Minolta CM-3700d spectrophotometer using a Xenon light-source, according to ISO 7724-1-2-3. The colour is measured in reflectance at 23 C. on the 80803 mm plaques; a white background, D65 illumination and geometry d/8 with observer 10, and a round measuring area with a diameter of 25.4 mm have been used

Comparative Experiment A and B

[0056] Comparative experiments A and B comprise only carbon black as black pigment. For the composition and the results of the CTI test and the color measurements see the table.

Comparative Experiment C

[0057] Comparative experiments comprise only nigrosin as black colorant. For the composition and the results of the CTI test and the color measurements see the table.

Examples 1 and 2

[0058] Examples 1 and 2 comprise both nigrosin and carbon black. For the composition and the results of the CTI test and the color measurements see the table.

TABLE-US-00001 TABLE Comp exp/example. A B 1 2 C Pocan 1400/PBT T04 201 67.55 67.3 67.5 67.5 67.3 Elvaloy AC 2615 5 5 5 5 5 LOTADER AX8900 3.5 3.5 3.5 3.5 3.5 Sb2 O3 MB 6.25 6.25 6.25 6.25 6.25 F2400 16 16 16 16 16 Carnaubawax T1 Flakes 0.25 0.25 0.25 0.25 0.25 Phenolic antioxidant 0.25 0.25 0.25 0.25 0.25 Eurotard AD 70 0.7 0.7 0.7 0.7 0.7 carbon black 0.5 0.75 0.05 0.05 Nigrosine black 0.5 0.5 0.75 100 100 100 100 100 CTI (Volts) 300 275 600 600 325 L* 32 31 29.91 30.5 29.51 a* 0.1 0.1 0.07 0.15 0.09 b* 1.2 1.2 2.89 2.79 2.73
From the results it is clear that with the examples according to the invention a deep black color (lower L-value) is obtained and that nevertheless a very favorable CTI of 600 Volts is obtained. This while with the comparative experiments the CTI value is only about 50% of the one obtained in the examples while also a less deep black color is obtained.