Additive mixtures containing thermoplastic moulding...

Details Additive mixtures containing thermoplastic moulding... Additive mixtures containing thermoplastic moulding...

2001-09-19

2003-08-05

Sanders, Kriellion A. (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...

C524S062000, C524S232000, C524S251000, C524S394000, C524S399000, C524S400000

Reexamination Certificate

active

06602939

ABSTRACT:

The subject of the present invention are compositions containing matrix polymer, graft polymer and special additive mixtures, their use for the production of moulded articles, as well as the moulded articles obtainable therefrom. The subject of the invention is also the additive combination.
ABS moulding compositions have already been used for many years in large quantities as thermoplastic resins for the production of all types of moulded parts. The property spectrum of these resins ranges from relatively brittle to extremely tough.
A special area of use of ABS moulding compositions is the production of moulded parts by injection moulding (e.g. housings, toys, vehicle parts), an important factor being in particular a very good flowability of the polymer material. Also, the moulded parts produced in this way must as a rule have a good notched-bar impact strength as well as a good resistance to thermal stresses.
The object therefore exists of achieving, for a given rubber content, a given rubber particle size and given matrix resin molecular weight, toughness values that are as high as possible while retaining the good thermoplastic flowability. In this connection the high toughness values should as far as possible be obtained independently of the type of matrix resin that is employed, and especially when using the styrene/acrylonitrile copolymers and &agr;-methylstyrene/acrylonitrile copolymers typical of ABS.
One possible way of improving the toughness of ABS polymers with a given rubber content, given rubber particle size and given matrix molecular weight is to add special silicone oil compounds (see EP-A 6521); however, disadvantages may arise such as poor paintability, unsatisfactory printability or impaired yield stress values (danger of stress whitening). The addition of minor amounts of EPDM rubber (see EP-A 412 370) or AES polymer (see EP-A 412 371) has also been described. Both methods require the use of considerable amounts of relatively expensive additive components however.
The use of large amounts of individual low molecular weight additive components may in special cases improve the processability, although this is normally offset by a negative effect on other properties such as for example toughness, modulus of elasticity and thermal stability.
It has now been found that by using special additive mixtures, ABS products can be obtained having a very good combination of notched-bar impact strength (at room temperature as well as at low temperatures) and excellent processability.
The invention provides thermoplastic moulding compounds or compositions containing
A) 5 to 95 wt. %, preferably 10 to 90 wt. % and particularly preferably 20 to 75 wt. % of one or more thermoplastic homopolymers, copolymers or terpolymers of styrene, &agr;-methylstyrene, nuclear-substituted styrene, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic anhydride, N-substituted maleimide or mixtures thereof,
B) 5 to 95 wt. %, preferably 10 to 90 wt. % and particularly preferably 25 to 80 wt. % of one or more graft polymers of
B.1) 5 to 90 parts by weight, preferably 20 to 80 parts by weight and particularly preferably 25 to 60 parts by weight of styrene, &agr;-methylstyrene, nuclear-substituted styrene, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic anhydride, N-substituted maleimide or mixtures thereof, on
B.2) 95 to 10 parts by weight, preferably 80 to 20 parts by weight and particularly preferably 75 to 40 parts by weight of at least one rubber having a glass transition temperature of ≦10° C.
and
C) 0.05 to 10 parts by weight, preferably 0.1 to 8 parts by weight and particularly preferably 0.5 to 5 parts by weight, in each case per 100 parts by weight of A)+B), of a combination of at least 3 components selected from compounds I), II), III) and IV), wherein I) denotes a compound with at least one structural unit
 where
M=metal, preferably Mg, Ca, Zn
n=valency of the metal M, preferably 1 or 2
II) denotes a compound with at least one structural unit
 and at least one structural unit
wherein R
1
and R
2
are, independently of one another, H or C
1
-C
20
hydrocarbon radicals,
III) denotes a compound with at least one structural unit
 and
IV) denotes a compound with structural units that are different from the specified structural units or combination of structural units contained in the compounds (I) to (III), i.e. the compounds (IV) contain none of the structural units or combinations of structural units contained in the compounds (I) to (III).
Preferably each of the compounds I) to IV) contains at least one terminal aliphatic C
6
-C
32
hydrocarbon radical.
According to the invention suitable thermoplastic polymers A) are those of styrene, &agr;-methylstyrene, p-methylstyrene, vinyltoluene, halogenated styrene, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, N-substituted maleimide or mixtures thereof.
The polymers A) are resin-like, thermoplastic and rubber-free. Particularly preferred polymers A) are those of styrene, methyl methacrylate, styrene/acrylonitrile mixtures, styrene/acrylonitrile/methyl methacrylate mixtures, styrene/methyl methacrylate mixtures, acrylonitrile/methyl methacrylate mixtures, &agr;-methylstyrene/acrylonitrile mixtures, styrene/&agr;-methylstyrene/acrylonitrile mixtures, &agr;-methylstyrene/methyl methacrylate/acrylonitrile mixtures, styrene/&agr;-methylstyrene/methyl methacrylate mixtures, styrene/(&agr;-methylstyrene/methyl methacrylate/acrylonitrile mixtures, styrene/maleic anhydride mixtures, methyl methacrylate/maleic anhydride mixtures, styrene/methyl methacrylate/maleic anhydride mixtures and styrene/acrylonitrile/N-phenylmaleimide mixtures.
The polymers A) are known and can be produced by free-radical polymerisation, in particular by emulsion, suspension, solution or bulk polymerisation. The polymers preferably have molecular weights {overscore (M)}
w
of 20,000 to 200,000 and intrinsic viscosities [&eegr;] of 20 to 110 ml/g (measured in dimethylformamide at 25° C.).
Suitable rubbers for the production of the graft polymers B) are in particular polybutadiene, butadiene/styrene copolymers, butadiene/acrylonitrile copolymers, polyisoprene or alkyl acrylate rubbers based on C
1
-C
8
alkyl acrylates, in particular ethyl acrylate, butyl acrylate and ethylhexyl acrylate.
The acrylate rubbers may optionally contain up to 30 wt. % (referred to the rubber weight) of monomers such as vinyl acetate, acrylonitrile, styrene, methyl methacrylate and/or vinyl ether incorporated by copolymerisation. The acrylate rubbers may also contain small amounts, preferably up to 5 wt. % (referred to the weight of rubber) of crosslinking, ethylenically unsaturated monomers incorporated by polymerisation. Crosslinking agents are for example alkylene diol diacrylates and methacrylates, polyester diacrylates and methacrylates, divinyl benzene, trivinyl benzene, triallyl cyanurate, allyl acrylate and methacrylate, butadiene and isoprene. Graft bases may also be acrylate rubbers with a core/shell structure, with a core of crosslinked diene rubber of one or more conjugated dienes such as polybutadiene, or a copolymer of a conjugated diene with an ethylenically unsaturated monomer such as styrene and/or acrylonitrile.
Further suitable rubbers are for example the so-called EPDM rubbers (polymers of ethylene, propylene and a non-conjugated diene such as for example dicyclopentadiene), EPM rubbers (ethylene/propylene rubbers) and silicone rubbers that may optionally have a core/shell structure.
Preferred rubbers for the production of the graft polymers B) are diene rubbers and alkyl acrylate rubbers as well as EPDM rubbers.
The rubbers in the graft polymer B) are present in the form of at least partially crosslinked particles having a mean particle diameter (d
50
) of 0.05 to 20 &mgr;m, preferably 0.1 to 2 &mgr;m and particularly preferably 0.1 to 0.8 &mgr;m. The mean particle diameter d
50
is determined by ultracentrifuge measurements according to W. Scholtan et al., Kolloid-Z. u.Z. Polymere

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