CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application (under 35 U.S.C. § 371) of PCT/EP2017/059706, filed Apr. 25, 2017, which claims benefit of European Application No. 16167315.7, filed Apr. 27, 2016, both of which are incorporated herein by reference in their entirety.

The present invention relates to permanently antistatically endowed thermoplastic moulding materials and compositions thereof comprising at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester, to the use of the moulding materials for producing moulded articles and to the moulded articles themselves.

The invention further provides for the use of pigments based on titanium dioxide for improving toughness and electrical surface conductivity of compositions endowed with polyether-based polymers and comprising at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester.

BACKGROUND OF THE INVENTION

The accumulation of dust with the formation of dust figures caused by electrostatic charging is a widespread problem in moulded plastics articles. Dust deposits on high-gloss moulded articles are particularly troublesome and functionally limiting.

The abovementioned problems are often solved by application of an antistatic coating (for example by painting). Examples of relevant fields of application include housings applications in information technology and decorative automotive interior components. Especially in the latter field of application a high material ductility even at low temperatures is generally a further component requirement.

If a downstream coating process is to be eschewed the moulding materials must naturally not only possess the desired mechanical properties but must moreover also inherently possess the required surface properties (high electrical dissipative conductivity/low specific electrical surface resistance). However, the required combination of ductility even at low temperatures and high electrical dissipative conductivity is often not sufficiently realized by thermoplastic compositions of the prior art.

Polycarbonate combinations are often employed in the recited fields of application because of their advantageous combination of properties including good processability (high melt flowability), exceptional mechanical properties, high heat distortion resistance and flame retardancy. Additionally, while permanently antistatically endowed polycarbonate compositions are known in principle, the addition of the additives required therefor generally, has a deleterious effect on the properties sought.

The provision of polycarbonate compositions which are not only sufficiently permanently antistatic but also possess low-temperature toughness is thus also an insufficiently solved technical problem.

The literature describes antistats for thermoplastics (see for example Gächter, Müller, Plastic Additives, Hanser Verlag, Munich 1996, p. 749 et seq.) which reduce dust accumulation. These antistats reduce the electric surface resistance of the plastics moulding materials, thus better discharging surface charges which form during production and through friction during use. Dust particles are thus electrostatically attracted to a lesser extent.

Polyetheramides, polyesteramides or polyetheresteramides are commonly described antistats and these compounds are capable of endowing polyester compositions with a permanent antistatic activity. Their activity is based on the formation of a three-dimensional network of the antistat in the antistat-immiscible polymer to be antistatically endowed. On account of the comparatively high electrical conductivity of polyetheramides, polyesteramides and polyetheresteramides this results in an instant and permanent reduction in the electrical surface and volume resistance of the polymer to be antistatically endowed, onset of which occurs even at very low atmospheric humidities and is far less dependent thereupon than is the case for the surface-active compounds such as salts of long-chain sulphonic acids likewise recited in the literature.

Permanently antistatically endowed polycarbonate compositions are disclosed for example in U.S. Pat. No. 6,784,257 B2. This application describes antistatic polymer compositions comprising a thermoplastic polymer and a polyether-polyamide block copolymer having a melting point between 80° C. and 150° C., wherein the polyether blocks comprise ethylene oxide units.

U.S. Pat. No. 6,706,851 B1 discloses antistatic polymer compositions comprising a thermoplastic polymer and a polyetheresteramide block copolymer, wherein the polyether blocks consist essentially of ethylene oxide units.

U.S. Pat. No. 6,913,804 B2 discloses antistatic polymer compositions comprising a thermoplastic polymer and a mixture of a copolymer which comprises polyamide and polyether blocks and does not comprise any ionically-functional groups and a copolymer comprising polyamide and polyether blocks which does comprise conically-functional groups.

All three of the abovementioned patents also disclose compositions in which the thermoplastic polymer is polycarbonate, ABS or a mixture thereof.

CN 101967274 A discloses permanently antistatic polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) compositions having excellent mechanical properties and weathering resistance comprising polycarbonate, an ABS resin, antistatic agents, compatibilizers, antioxidants, light stabilizers and other additives. Antistatic agents disclosed include polyetheresters, polyetheresteramides and polyetheramides.

CN 101759974 A discloses antistatic polycarbonate compositions having low odour and high toughness for automotive interior applications comprising polycarbonate, ABS resin produced in a bulk polymerization process and having a melt flow index of 4 to 25 g/10 min, a polymeric antistatic agent, a compatibilizer and optionally further additives selected from for example the group comprising colourants, fillers, stabilizers and lubricants. Antistatic agents disclosed include polyetheramides.

JP 3663701 B2 discloses antistatic polycarbonate compositions comprising polycarbonate, rubber-modified thermoplastic comprising vinyl polymer and graft polymer obtained by grafting vinyl monomers onto rubber-like polymers and polyetheramides.

DE 3544295 A1 discloses moulding materials comprising halogenated copolycarbonates, graft polymers based on an acrylate rubber, thermoplastic copolymers, tetrafluoroethylene polymers, metal compounds of antimony or bismuth, titanium dioxide and optionally low molecular weight, organic halogen compounds, stabilizers, flow agents, antistats and/or demoulding agents. The moulding materials feature a combination of good flame retardancy, tracking resistance, thermal resilience and processability.

WO 2012/084848 A1 discloses antistatic polycarbonate moulding materials having improved heat distortion resistance, low-temperature toughness, processing stability, stress fracture resistance and hydrolysis resistance comprising polycarbonate, rubber-modified vinyl (co)polymer, a compound selected from the group consisting of polyetheramides, polyesteramides and polyetheresteramides, a special Brønsted acid and optionally further additives.

It was desirable to provide permanently antistatic compositions comprising at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester having an improved combination of lowest possible specific electrical surface resistance (sufficiently high electrical dissipative conductivity) and low-temperature ductility. The compositions should moreover exhibit high heat distortion resistance. The compositions should accordingly fulfill the requirements of the automotive industry for unpainted decorative components in automotive interiors. Such a composition as is disclosed in the present invention has not hitherto been described in the prior art.

BRIEF SUMMARY OF THE INVENTION

It has now been found that compositions comprisingA) 50 to 90% by weight, preferably 60 to 80% by weight, particularly preferably from 65 to 75% by weight, of at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester, preferably aromatic polycarbonate,B) 5 to 40% by weight, preferably 10 to 30% by weight, particularly preferably 15 to 25% by weight, of rubber-based graft polymer or a mixture of rubber-based graft polymer and rubber-free vinyl (co)polymer,C) 3 to 25% by weight, preferably 5 to 15% by weight, particularly preferably 6 to 12% by weight, of at least one polyether-based polymer or copolymer selected from the group consisting of polyether block polymers and polyether-based polyurethanes,D) 0.8 to 9% by weight, preferably 2 to 8% by weight, particularly preferably 3 to 7% by weight, of at least one pigment based on titanium dioxide,E) 0 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.2 to 10% by weight, of one or more further additives,have the advantageous properties.

In a preferred embodiment components C and D are employed in a ratio of C/D, in % by weight in each case, of 0.7 to 15, preferably of 1 to 6, particularly preferably of 1.1 to 4, most preferably of 1.2 to 2.5.

A further embodiment of the present invention is the use of pigments based on titanium dioxide for improving toughness and surface conductivity of compositions endowed with polyether block polymers and comprising at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester.

Particular embodiments 1 to 31 of the present invention are listed hereinbelow.

1. Compositions comprising

A) 50 to 90% by weight of at least one representative selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester,

B) 5 to 40% by weight of rubber-based graft polymer or a mixture of rubber-based graft polymer and rubber-free vinyl (co)polymer,

C) 3 to 25% by weight of at least one polyether-based polymer or copolymer selected from the group consisting of polyether block polymers and polyether-based polyurethanes,

D) 0.8 to 9% by weight of at least one pigment based on titanium dioxide,

E) 0 to 20% by weight of one or more further additives.

2. Compositions according to embodiment 1, wherein component A comprises aromatic polycarbonate.

3. Compositions according to embodiment 1, wherein component A is aromatic polycarbonate.

4. Compositions according to any of the preceding embodiments, wherein the graft polymers employed in component B compriseB.1 5 to 95% by weight, based on the graft polymer, of at least one vinyl monomer onB.2 95 to 5% by weight, based on the graft polymer, of one or more rubber-elastic graft substrates having glass transition temperatures <−50° C.

5. Compositions according to embodiment 4, wherein the graft substrate B.2 is pure polybutadiene rubber.

6. Compositions according to embodiment 4, wherein the graft substrate B.2 is styrene-butadiene block copolymer rubber.

7. Compositions according to any of the preceding embodiments, wherein component B comprises vinyl (co)polymer not chemically bonded to the rubber substrate and not included in the rubber particles which consists of the monomers according to B.1 in a proportion of at least 5% by weight based on component B.

8. Compositions according to any of the preceding embodiments, wherein component B comprises vinyl (co)polymer not chemically bonded to the rubber substrate and not included in the rubber particles which consists of the monomers according to B.1 in a proportion of at least 50% by weight based on component B.

9. Compositions according to any of the preceding embodiments, wherein components C and D are employed in a weight ratio C/D of 1.1 to 4.

10. Compositions according to any of the preceding embodiments, wherein components C and D are employed in a weight ratio C/D of 1.2 to 2.5.

11. Compositions according to any of the preceding embodiments, wherein component C is a block copolymer comprising polyethylene glycol and polyamide blocks.

12. Compositions according to any of the preceding embodiments, wherein component C is a block copolymer composed of polyethylene glycol and polyamide 12 blocks.

13. Compositions according to any of the preceding embodiments, wherein component C has a specific electrical surface resistance of ≤1013Ω.

14. Compositions according to any of the preceding embodiments, wherein component C has a specific electrical surface resistance of ≤1011Ω.

15. Compositions according to any of the preceding embodiments, wherein component D consists to an extent of at least 95% by weight of titanium dioxide in the rutile modification.

16. Compositions according to any of the preceding embodiments, wherein component D is employed in a proportion of 0.8 to 8% by weight.

17. Compositions according to any of the preceding embodiments, wherein component D is employed in a proportion of 2 to 8% by weight.

18. Compositions according to any of the preceding embodiments, wherein component D is employed in a proportion of 3 to 7% by weight.

19. Compositions according to any of embodiments 1 to 16, wherein component D is employed in a proportion of 0.8 to 7% by weight.

20. Compositions according to any of embodiments 1 to 16, wherein component D is employed in a proportion of 0.8 to 5% by weight.

21. Compositions according to any of embodiments 1 to 16, wherein component D is employed in a proportion of 0.8 to 3% by weight.

22. Compositions according to any of embodiments 1 to 16, wherein component D is employed in a proportion of 1.5 to 5% by weight.

23. Compositions according to any of embodiments 1 to 16, wherein component D is employed in a proportion of 1.5 to 3% by weight.

24. Composition according to any of the preceding embodiments, comprising as component E at least one additive selected from the group consisting of lubricants and demoulding agents, stabilizers, flow promoters, compatibilizers and dyes and pigments distinct from component D.

25. Compositions according to any of the preceding embodiments, wherein as component E a salt which increases the conductivity of the component is further employed.

26. Compositions according to any of the preceding embodiments, wherein as component E potassium bis(oxalato) borate or sodium bis(oxalato) borate is further employed.

27. Compositions according to any of the preceding embodiments consisting of components A) to E).

28. Use of compositions according to any of embodiments 1 to 27 for producing moulded articles.

29. moulded articles produced from compositions according to any of embodiments 1 to 27.

30. Use of pigments based on titanium dioxide for improving toughness and electrical surface conductivity of compositions endowed with polyether-based polymers and comprising at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester.

31. Use according to embodiment 30, wherein compositions according to any of embodiments 1 to 27 are employed.

