Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-08-16
2004-07-27
Mullis, Jeffrey (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...
C525S067000, C525S068000, C525S069000, C525S071000
Reexamination Certificate
active
06767964
ABSTRACT:
ABS moulding compositions or moulding compositions of the ABS type have already been used for many years in large amounts as thermoplastic resins for producing moulded parts of all types. In this connection the property spectrum of these resins can be varied within wide ranges.
Particularly important properties of ABS moulding compositions that may be mentioned include toughness (impact strength, notched impact strength), modulus of elasticity, processability (MVR), heat resistance, surface gloss, attention being paid in general to specific property combinations depending on the area of use.
A particularly important feature for the processing of ABS moulding compositions, particularly when using fully automated production plants, is the constancy of the properties or property combinations of the moulding compositions to be processed.
Although products with relatively narrow tolerance limits can be produced by using modern processes in the ABS production (for example computerised control of polymerisation and compounding) nevertheless for special applications it is necessary to have even more improved constant properties that can be achieved only via the product composition or the product structure.
The object therefore existed of producing thermoplastic moulding compositions of the ABS type having a very constant property profile.
The object according to the invention is achieved by using combinations of two graft rubber polymers, in the production of which are employed rubbers with defined particle diameters obtained by seed polymerisation using seed latex particles with defined particle diameters.
The present invention provides polymer compositions containing
I) at least one graft rubber polymer obtained by emulsion polymerisation of styrene and acrylonitrile in a weight ratio of 95:5 to 50:50, styrene and/or acrylonitrile being able to be partially or completely replaced by &agr;-methylstyrene, methyl methacrylate or N-phenylmaleimide or mixtures thereof, in the presence of a butadiene polymer latex (A) with a mean particle diameter d
50
of 80 to 220 nm, preferably 90 to 210 nm, and particularly preferably 100 to 200 nm,
II) at least one graft rubber polymer obtained by emulsion polymerisation of styrene and acrylonitrile in a weight ratio of 95:5 to 50:50, styrene and/or acrylonitrile being able to be completely or partially replaced by &agr;-methylstyrene, methyl methacrylate or N-phenylmaleimide or mixtures thereof, in the presence of a butadiene polymer latex (B) with a mean particle diameter d
50
of 340 to 480 nm, preferably 350 to 470 nm, and particularly preferably 360 to 460 nm,
III) at least one rubber-free copolymer of styrene and acrylonitrile in a weight ratio of 95:5 to 50:50, styrene and/or acrylonitrile being able to be completely or partially replaced by &agr;-methylstyrene, methyl methacrylate or N-phenylmaleimide or mixtures thereof,
characterised in that the butadiene polymer latex (A) was obtained by seed polymerisation using a seed latex with a mean particle diameter of 10 to 100 nm, preferably 20 to 90 nm, and particularly preferably 30 to 80 nm, and the butadiene polymer latex (B) was obtained by seed polymerisation using the butadiene polymer latex (A) as seed latex.
The present invention also provides a process for producing the polymer compositions according to the invention, wherein the butadiene polymer latex (A) is obtained by seed polymerisation using a seed latex with a mean particle diameter of 10 to 100 nm and the butadiene polymer latex (B) is obtained by seed polymerisation using the butadiene polymer latex (A) as seed latex.
In general the polymer compositions according to the invention may contain the graft rubber components (I)+(II) in amounts of 1 to 60 parts by weight, preferably 5 to 50 parts by weight, and the rubber-free resin component (III) in amounts of 40 to 99 parts by weight, preferably 50 to 95 parts by weight.
The weight ratio of (I):(II) may be varied within wide limits; it is conventionally 90:10 to 10:90, preferably 80:20 to 30:70, and particularly preferably 70:30 to 40:60.
Apart from the aforementioned polymer components the polymer compositions according to the invention may contain further rubber-free thermoplastic resins not built up from vinyl monomers, these thermoplastic resins being used in amounts of up to 1000 parts by weight, preferably up to 700 parts by weight and particularly preferably up to 500 parts by weight (in each case referred to 100 parts by weight of I+II+III).
The butadiene polymer latices (A) and (B) are produced by emulsion polymerisation of butadiene according to the so-called seed polymerisation technique, in which first of all a finely particulate polymer, preferably a butadiene polymer, is produced as seed latex and is then polymerised further by reaction with butadiene-containing monomers into larger particles (see for example in Houben-Wyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, Part 1, p. 339 (1961), Thieme Verlag Stuttgart). In this connection the process is preferably carried out using a seed batch process or a continuous seed flow process.
As comonomers there may be used up to 50 wt. % (referred to the total amount of monomer used for the butadiene polymer production), of one or more monomers copolymerisable with butadiene.
Examples of such monomers include isoprene, chloroprene, acrylonitrile, styrene, &agr;-methylstyrene, C
1
-C
4
-alkylstyrenes, C
1
-C
8
-alkyl acrylates, C
1
-C
8
-alkyl methacrylates, alkylene glycol diacrylates, alkylene glycol dimethacrylates, divinyl benzene; preferably butadiene is used alone or mixed with up to 20 wt. %, preferably with up to 10 wt. %, of styrene and/or acrylonitrile.
As seed latex polymers there are preferably used butadiene polymers such as for example polybutadiene, butadiene/styrene copolymers, butadiene/acrylonitrile copolymers, or polymers obtained from the aforementioned monomers.
In principle there may also be used other finely particulate latex polymers, such as for example polystyrene or styrene copolymers, polymethyl methacrylate or methyl methacrylate copolymers, as well as polymers of other vinyl monomers.
Preferred seed latex polymers are polybutadiene latices.
In this connection a seed latex with a mean particle diameter d
50
of 10 to 100 nm, preferably 20 to 90 nm, and particularly preferably 30 to 80 nm, is used in the production of the butadiene polymer latex (A).
The butadiene polymer latex (A) is used as seed latex in the production of the butadiene polymer latex (B).
The seed latex for producing the butadiene polymer (A) has a gel content of 10 to 95 wt. %, preferably 20 to 90 wt. %, and particularly preferably 30 to 85 wt. %.
The butadiene polymer latex (A) has a mean particle diameter d
50
of 80 to 220 nm, preferably 90 to 210 nm, and particularly preferably 100 to 200 nm.
The gel content of (A) is 30 to 98 wt. %, preferably 40 to 95 wt. %, and particularly preferably 50 to 92 wt. %.
The butadiene polymer latex (B) has a mean particle diameter d
50
of 340 to 480 nm, preferably 350 to 470 nm, and particularly preferably 360 to 460 nm.
The gel content of (B) is 50 to 95 wt. %, preferably 55 to 90 wt. %, and particularly preferably 60 to 85 wt. %.
The mean particle diameter d
50
may be determined by ultracentrifuge measurements (see W. Scholtan, H. Lange: Kolloid Z. u. Z. Polymere 250, pp. 782 to 796 (1972)), the specified values for the gel content referring to the determination according to the wire cage method in toluene (see Houben-Weyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, Part 1, p. 307 (1961), Thieme Verlag Stuttgart).
The gel contents of the butadiene polymer latices (A) and (B) as well as of the seed polymer latex for producing the butadiene polymer latex (A) may in principle be adjusted in a known manner by employing suitable reaction conditions (e.g. high reaction temperature and/or polymerisation up to a high conversion, as well as optionally the addition of crosslinking substances in order to achieve a high gel content, or for example low reaction te
Eichenauer Herbert
Jansen Ulrich
Schmidt Adolf
Bayer Aktiengesellschaft
Gil Joseph C.
Mullis Jeffrey
Preis Aron
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