Stabilized thermoplastic molding materials

Details Stabilized thermoplastic molding materials Stabilized thermoplastic molding materials

2002-11-25

2004-12-28

Seidleck, James J. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S071000, C525S149000, C525S227000, C525S193000, C525S290000, C525S316000, C525S327300, C525S187000, C524S504000

Reexamination Certificate

active

06835776

ABSTRACT:

The invention relates to thermoplastic molding compositions comprising, based on components A) to F),
A) from 5 to 70% by weight of at least one graft copolymer A) made from, based on A),
a1) from 10 to 90% by weight of at least one elastomeric graft base with a glass transition temperature below 0° C., and
b2) from 10 to 90% by weight of at least one graft made from, based on a2),
a21) from 50 to 100% by weight of at least one styrene compound,
a22) from 0 to 50% by weight of acrylonitrile or methacrylonitrile, or a mixture of these, and
a23) from 0 to 50% by weight of at least one other monoethylenically unsaturated monomer,
B) from 29 to 90% by weight of a hard copolymer made from, based on B),
b1) from 50 to 100% by weight of at least one styrene compound,
b2) from 0 to 50% by weight of acrylonitrile or methacrylonitrile, or a mixture of these, and
b3) from 0 to 50% by weight of at least one other monoethylenically unsaturated monomer,
C) from 0 to 5% by weight of at least one three-block copolymer X-Y-X having a central block Y made from propylene oxide units and having terminal blocks X made from ethylene oxide units,
D) from 0.01 to 5% by weight of at least one butylated reaction product of p-cresol with dicyclopentadiene of the formula (I)
where n≦10,
E) from 0.01 to 5% by weight of at least one thiocarboxylic ester,
F) from 0.01 to 5% by weight of at least one alkali metal salt, or alkaline earth metal salt, of a C
6
-C
20
carboxylic acid, and
G) from 0 to 30% by weight, based on components A) to G), of other conventional additives,
where the weathered db* value of the molding compositions is below +5.0 after 100 hours of exposure to light and weathering to ISO 4892/2, method A, black-panel temperature 65° C., using the CIE-Lab color system, to DIN 6174 and DIN 5033.
The invention also relates to processes for preparing the molding compositions, and to the use of the molding compositions for preparing moldings, fibers and films, and also to the moldings, fibers and films.
Impact-modified styrene-acrylonitrile polymers, such as ABS (polybutadiene rubber particles grafted with polystyrene-acrylonitrile, in a polystyrene-acrylonitrile matrix) or ASA (polyalkyl acrylate rubber, structure otherwise as ABS) are used in a wide variety of applications. They are preferably used to produce moldings intended to have good mechanical properties. It is often necessary to use additives to give the molding compositions certain properties, such as antistatic properties, and in particular good weathering resistance, etc.
French Patent 1 239 902 discloses thermoplastic molding compositions comprising an antistatic, EO-PO-EO three-block copolymers (EO is ethylene oxide, and PO is propylene oxide).
EP-A 135 801 describes blends made from polycarbonate, from ABS or ASA and from an EO-PO-EO three-block copolymer, with certain molar masses for individual blocks.
EP-A 536 483 discloses ABS molding compositions which comprise a PO polymer whose ends have been capped with EO and which contains 1,4-butylene terephthalate units.
U.S. Pat. No. 5,346,959 describes blends made from ABS, from styrene-maleic anhydride copolymer, and from OH-functionalized PO-EO-PO block copolymers (i.e. an EO central block).
DE-OS 16 940 101 describes ABS molding compositions stabilized with a phenolic stabilizer, with dilauryl thiodipropionate, and with C
1
-C
20
fatty esters (butyl stearate).
British Patent 1 369 589 discloses styrene-butadiene-acrylonitrile copolymers which comprise phenolic stabilizers and dilauryl thiodipropionate, besides asbestos fibers.
EP-A 184 788 discloses flame-retardant ABS molding compositions which comprise stearically hindered phenols and costabilizers.
WO-A 95/02639 describes the stabilization of recycled styrene-containing plastic from waste and collection of useful materials. The stabilizers used comprise stearically hindered phenols, metal oxides/metal hydroxides/metal carbonates, esters of thiodipropionic acid, and, if desired, metal salts of fatty acids.
WO-A 94/07951 discloses the stabilization of plastics from waste, using a mixture made from a stearically hindered phenol, from an organic phosphite or phosphonite, and from metal oxides/metal hydroxides/metal carbonates.
EP-A 506 614 describes the stabilization of recycled thermoplastics using stearically hindered phenols and phosphoric esters.
EP-A 669 367 describes ABS molding compositions stabilized with a trialkyl phenol, with a stearically hindered phenol, and, if desired, with dilauryl or distearyl thiodipropionate.
EP-A 712 894 discloses ABS molding compositions, mentioning, inter alia, stearically hindered phenols as stabilizers.
DE-A 197 50 747 describes stabilizers for styrene co- and terpolymers, such as ABS, composed of a stearically hindered phenol, of dilauryl and/or distearyl thiodipropionate, and of a phosphite.
None of the documents discloses impact-modified styrene-acrylonitrile molding compositions which comprise all three of the additives D), E) and F), as described above, together, and where the weathered db* value of the molding compositions is below +5.0 after 100 hours of exposure to light and weathering to ISO 4892/2, method A, black-panel temperature 65° C., using the CIE-Lab color system, to DIN 6174 and DIN 5033.
A feature common to all of the prior art molding compositions is that their stabilization with respect to weathering (rain, UV light) and heat-aging is unsatisfactory or is achieved only by sacrificing other advantageous properties, in particular by sacrificing their good mechanical properties, such as toughness.
It is an object of the present invention to remove these disadvantages, and in particular to provide uncolored molding compositions which in particular when uncolored (i.e. without any addition of colorants which hide the intrinsic color of the molding compositions) have better weathering resistance and heat-aging resistance than the prior art molding compositions and which at the same time have a balanced mechanical property profile, in particular high toughness even after weathering and heat-aging. In addition, the molding compositions should have good flowability, and also good antistatic properties. Compared with prior art molding compositions, the molding compositions should show less color change on weathering.
The molding compositions should also ensure that moldings produced from them have reduced tendency to form dust patterns when the moldings are stored in a dusty atmosphere. In addition, the molding compositions should have improved colorant dispersion, that is to say that colorants, such as pigments, should be capable of particularly uniform dispersion in the molding compositions. Finally, the molding compositions should have better demoldability when injection-molded.
We have found that this object is achieved by means of the thermoplastic molding compositions defined at the outset, and also by processes for their preparation, by their use, and by the resultant moldings, fibers or films.
In the molding compositions of the invention, based in each case on components A) to F),
the proportion of component A) is from 5 to 70% by weight, preferably from 8 to 65% by weight, and particularly preferably from 10 to 60% by weight,
the proportion of component B) is from 29 to 90% by weight, preferably from 34 to 88% by weight, and particularly preferably from 39 to 85% by weight,
the proportion of component C) is from 0 to 5% by weight, preferably from 0.01 to 5% by weight, and particularly preferably from 0.01 to 4% by weight, in particular from 0.01 to 3% by weight,
the proportion of component D) is from 0.01 to 5% by weight, preferably from 0.03 to 4% by weight, and particularly preferably from 0.05 to 3% by weight,
the proportion of component E) is from 0.01 to 5% by weight, preferably from 0.03 to 4% by weight, and particularly preferably from 0.05 to 3% by weight,
the proportion of component F) is from 0.01 to 5% by weight, preferably from 0.02 to 4% by weight, and particularly preferably from 0.1 to 3% by weight, and
the proportion of component G), based on

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