Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-06-21
2004-05-18
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S116000, C524S127000, C524S148000
Reexamination Certificate
active
06737465
ABSTRACT:
The present invention relates to polycarbonate compositions filled with talc which, in addition to excellent flame resistance, are distinguished even at small wall thicknesses by improved rigidity, good resistance to stress cracking, i.e. resistance to chemicals, and by low tool abrasion and low coating formation (“juicing”) during processing.
Filled or reinforced PC/ABS moulding compositions are known.
EP-A 0 391 413 describes, for example, PC/ABS moulding compositions containing inorganic fillers having particular geometric properties, the moulding compositions being specified by a relatively low linear thermal expansion coefficient, high strength under impact loading, and a high dimensional stability under heat. Talc and uncalcined clay materials are described as fillers according to the invention. Flameproofing agents are mentioned only generally in a group of additives.
In EP-A 0 452 788 there are described talc-containing PC/ABS moulding compositions which are distinguished especially by a matt surface of the material. Here too, flameproofing agents are mentioned only generally.
Filled or reinforced PC/ABS moulding compositions which have been rendered flame-resistant are also already known.
JP-A 0 219 9162 describes reinforced, flame-resistant PC/ABS moulding compositions provided with a halogen-containing flameproofing agent having a halogen content of from 0.5 to 15 wt. %. Talc is mentioned generally as a possible filler.
EP-A 0 363 608 and EP-A 0 640 655 relate to PC/ABS moulding compositions which have been rendered flame-resistant by oligophosphoric acid esters or mixtures of oligo- and mono-phosphoric acid esters. It is mentioned in general that the moulding compositions may contain reinforcing materials. Examples of reinforced moulding compositions are not disclosed, however.
WO 99/07778 describes reinforced PC/ABS moulding compositions which have been rendered flame-resistant by organic phosphorus compounds, the polycarbonate content of those moulding compositions being a mixture of two aromatic polycarbonates having different solution viscosities. Only the use of glass fibres as reinforcing agent is demonstrated by means of examples. Those lead to undesirable tool abrasion during processing of the moulding composition. WO 99/07778 teaches that PC/ABS moulding compositions having a better modulus of elasticity, notched bar impact strength and processing properties are obtained when particular mixtures of polycarbonates of different viscosities are used.
In EP-A 0 754 531 it is mentioned that the use of fibrous fillers having a high L/D ratio leads to products having anisotropic properties (tensile strength, rigidity, linear thermal expansion coefficient, shrinkage ratio), which often has undesirable consequences such as warping, deformation on heating, etc. There is described a PC/ABS moulding composition which has been rendered flame-resistant by the use of particular oligophosphoric acid esters and reinforced by a filler having a lamellar structure. Examples containing glass flakes, micas and mixtures thereof as filler are disclosed in particular. Talc is not mentioned explicitly as a filler. EP-A 754 531 teaches that the described moulding compositions are distinguished by low deformation in the case of variations in temperature, allowing them to be used for high-precision components. Further advantages mentioned are a low tendency towards bleeding of the flameproofing agent and towards the formation of a coating in the injection-moulding tool.
JP-A 0 731 6411 describes PC/ABS moulding compositions which contain from 1 to 30% of an aromatic monophosphate as flameproofing agent and from 1 to 20% of a calcined talc having an average particle size of 2 &mgr;m or less as filler. The moulding compositions are distinguished by good processability, strength and dimensional stability under heat as well as by excellent flame protection. Experience teaches, however, that monophosphates tend to bleed and to form undesirable coatings on the tools during processing by injection moulding.
U.S. Pat. No. 5,849,827 and WO 99/07788 disclose flame-resistant thermoplastic moulding compositions, based on polycarbonate, which contain very finely divided inorganic powders. Talc is not mentioned. It is described that, by the addition of the finely divided inorganic powders, the after-burning times at 1.6 mm according to UL 94 V, and hence the flameproofing properties, are improved.
The object of the present invention is to improve the flame resistance (reduction of the after-burning times and dripping tendency in the UL 94 V test) in the case of thin wall thicknesses, especially of 1.5 mm and below, while at the same time increasing the rigidity of the material, which is especially important in the case of thin-walled mouldings. Furthermore, the moulding compositions are to have good resistance to stress cracking, good hydrolytic stability, a low warping tendency, good flowability, dimensional stability under heat and strength and, during processing, negligible tool abrasion and negligible coating formation as a result of bleeding of the flameproofing agent during processing.
It has now been found that impact-modified polycarbonate compositions which contain the particular talc described below have the desired properties. The profile of properties of the compositions according to the invention especially permits their use in the production of thin-walled mouldings, especially for applications which require reliable flame protection.
Accordingly, the present invention provides polycarbonate compositions containing impact modifier, at least one phosphorus-containing flameproofing agent, and
from 0.05 to 40 parts by weight, preferably from 0.5 to 30 parts by weight, particularly preferably from 1 to 20 parts by weight, based on the total composition, of a particular highly pure talc having an MgO content of from 28 to 35 wt. %, preferably from 30 to 33 wt. %, particularly preferably from 30.5 to 32 wt. %, and an SiO
2
content of from 55 to 65 wt. %, preferably from 58 to 64 wt. %, particularly preferably from 60 to 62.5 wt. %, in each case based on the talc.
Especially preferred types of talc are further distinguished by an Al
2
O
3
content of less than 5 wt. %, especially less than 1 wt. %, more especially less than 0.7 wt. %, based on the talc.
Preference is given to polycarbonate compositions containing
A) from 40 to 98 parts by weight, preferably from 45 to 95 parts by weight, particularly preferably from 50 to 90 parts by weight, of at least one aromatic polycarbonate,
B) from 0.5 to 50 parts by weight, preferably from 1 to 35 parts by weight, particularly preferably from 1.5 to 25 parts by weight, of at least one graft polymer,
C) from 0.5 to 40 parts by weight, especially from 2 to 20 parts by weight, of at least one phosphorus-containing flameproofing agent,
D) from 0.05 to 40 parts by weight, especially from 0.5 to 30 parts by weight, particularly preferably from 1 to 20 parts by weight, of a talc according to the above definition.
The sum of the parts by weight of all the components (A to D and, optionally, further constituents) is 100.
Very particularly preferred polycarbonate compositions are distinguished especially by the fact that, at wall thicknesses of less than or equal to 1.5 mm, preferably at wall thicknesses of 1.2 mm or less, they pass the UL 94V test with the rating V-0.
Component A
Aromatic polycarbonates and/or aromatic polyester carbonates according to component A which are suitable according to the invention are known in the literature or can be prepared by processes which are known in the literature (for the preparation of aromatic polycarbonates see, for example, Schnell, “Chemistry and Physics of Polycarbonates”, Interscience Publishers, 1964 and DE-AS 1 495 626, DE-OS 2 232 877, DE-OS 2 703 376, DE-OS 2 714 544, DE-OS 3 000 610, DE-OS 3 832 396; for the preparation of aromatic polyester carbonates see, for example, DE-OS 3 077 934).
The preparation of aromatic polycarbonates is carried out, for example, by reacting diphenols with carbonic acid halides,
Derr Torsten
Eckel Thomas
Seidel Andreas
Wittmann Dieter
Zobel Michael
Bayer Aktiengesellschaft
Gil Joseph C.
Preis Aron
Szekely Peter
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