Heterophasic polyolefin alloy

Details Heterophasic polyolefin alloy Heterophasic polyolefin alloy

1999-06-30

2002-01-15

Michl, Paul R. (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...

C524S525000, C525S072000

Reexamination Certificate

active

06339123

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to heterophasic polyolefin alloys with a semi-interpenetrating network structure and an outstanding combination of high stiffness and low temperature toughness and optionally with a low coefficient of thermal expansion, consisting of propylene polymers and modified elastomers, which are suitable for the manufacture of films, sheets, fibers, panels, coatings, injection molded articles, pipes, hollow objects and foams. The invention also relates to a method for producing these heterophasic polyolefin alloys.
Thermoplastic elastomers, as heterophasic polyolefin alloys of high toughness, are known. Known elastomeric components for thermoplastic elastomers based on polypropylene are ethylene propylene elastomers (EP 672 712; EP 614 940), ethylene propylene diene elastomers (EP 547 843; EP 409 542), ethylene vinyl acetate copolymers (BE 899507; Coran, A., Rubber Chem. Technol. 54 (1981), 892), chlorosulfonated polyethylene (U.S. Pat. No. 4,141,878), elastomeric copolymers of ethylene and C
4
to C
8
olefins, such as elastomeric ethylene butene copolymers (Kautschuk-Gummi-Kunststoffe 49 (1996) 12, 812-813), ethylene hexene copolymers or ethylene octene copolymers (Yu, T. J. Plastic Film and Sheeting 10 (1994) 1, 539-564), as well as elastomeric atactic polypropylenes (EP:334-829) in amounts of 35 to 70% by weight, based on the polyolefin mixture.
The composition of the polyolefin components and of the elastomeric components and the distribution of the elastomeric components in the polyolefin component are of decisive significance for the material properties of heterophasic polyolefin alloys with elastomers, such as strength and elasticity (Moore, P., Polypropylene Handbook, Carl Hanser-Verlag Munich 1996, 218 to 225).
It is furthermore known that the elastomeric components in polyolefin alloys, which are based on polypropylene/ethylene propylene diene elastomers, can be vulcanized by additions, such as dodecyl mercaptan (DE 26 20 820), sulfur (EP 336 780) or tetrabutyl thiuram disulfide (EP 376 213). However, these formulations have the disadvantage of discoloring severely, so that semi-finished and molded products of these materials can be used only if they are dyed black.
Heterophasic polyolefin alloys based on polypropylene and elastomeric C
4
to C
8
olefins can be dyed particularly well. However, compared to heterophasic polyolefin alloys based on polypropylenes and vulcanized ethylene propylene diene elastomers, they have a significantly lower strength level.
For formulations from polypropylenes and elastomeric ethylene hexene copolymers, it is known that the blends can be modified by electron beam radiation (JP 96 301 927).
Furthermore, grafting of polyethylene as well as of ethylene copolymers with ethylenically unsaturated hydrolyzable organosilane compounds and the hydrolytic cross linking of these grafted copolymers is known (German patent 26 11 491; U.S. Pat. No. 3,646,155; British patent 1,406,680).
It is also known that the impact strength of polypropylenes can be modified by the addition of 10 to 35% by weight of amorphous ethylene propylene diene elastomers (Michaeli, W., Z. Kunststoffberater (1990) 3, 38-43; Kloos, F., Angewandte Makromolekulare Chemie 185/186 (1991), 97-108), ethylene propylene elastomers (Kim, B., J. Applied Polymer Science 60 (1996), 2207-2218, J. Applied Polymer Science 60 (1996), 1391-1403), likewise in the form of reactor blends of polypropylene and ethylene and ethylene propylene rubber (Kresge, E., Macromol. Symp. 53 (1992), 173-189, Schwager, H. Kunststoffe 82 (1992) 6, 499-501), ethylene butene elastomers (Yu, C., SPE-ANTEC 94, 2439-2442, SPE-ANTEC '96, 1995-2000), ethylene hexene copolymers (J 08 301 927, Yamaguchi, M., J. Applied Polymer Science 63 (1997), 467-474) and ethylene octene elastomers (EP 0 769 525, J 97 48 920).
DETAILED DESCRIPTION OF THE INVENTION
The object of the invention is to form heterophasic polyolefin alloys from propylene polymers and elastomers, which have a high stiffness, a low temperature toughness and optionally a low coefficient of thermal expansion.
Surprisingly, it was found that, by melt compounding partially cross linked blends, which were synthesized by the reaction of elastomeric polyolefins or styrene ethylene butadiene terpolymers or of mixtures of propylene polymers and elastomeric polyolefins or styrene ethylene butadiene terpolymers with ethylenically unsaturated, hydrolyzable organosilane compounds in the presence of free radical-forming agents and silanol condensation catalysts, with an excess of propylene polymers, heterophasic polyolefin alloys with a semi-interpenetrating network structure can be produced, which fulfill these requirements. At the same time, it was observed that the partially cross linked elastomeric polyolefins formed are distributed homogeneously in the polypropylene matrix as extended, filamentous network structures.
The objective of the invention was accomplished by heterophasic polyolefin alloys with a semi-interpenetrating network structure and an outstanding combination of high stiffness, low temperature toughness and optionally a low coefficient of thermal expansion, which consists of 65 to 99.6% by weight of propylene polymers and 35 to 0.4% by weight of elastomeric polyolefins or styrene ethylene butadiene terpolymers and optionally 0.01 to 2.5% by weight of stabilizers, 0.01 to 1% by weight of processing aids, 0.1 to 1% by weight of antistatic agents, 0.2 to 3% by weight of pigments, 0.05 to 1% by weight of nucleating agents and/or 2 to 20% by weight of flame retardants, in each case based on the sum of the polymers, as auxiliary materials, and/or optionally 10 to 70% by weight and preferably 20 to 50% by weight, based on the sum of the polymers, of inorganic and/or organic fillers and/or reinforcing materials, the heterophasic polyolefin alloys, pursuant to the invention, having a gel content of
G
HP
=10
−2
C
B
(
G
B
+N
(100
−G
B
)).
wherein
G
HP
=gel portion of the heterophasic polyolefin alloys in % by weight
C
B
=Concentration of the co-continuous blend B in the polyolefin alloy in % by weight
G
B
=gel portion of the co-continuous blend B in % by weight
N=post cross linking factor=0.10 to 0.90
and being prepared by melt compounding 60 to 98% by weight of conventional propylene homopolymers or propylene copolymers A with melt indexes ranging from 0.1 to 50 g/10 minutes at 230° C./2.16 kg with 40 to 2% by weight of a co-continuous blend B, optionally with the addition of 0.01 to 0.5% by weight of silanol condensation catalysts and/or 0.01 to 0.5% of water,
and wherein the co-continuous blends B on the basis of
B1) conventional propylene polymers or propylene copolymers with melt indexes ranging from 0.1 to 50 g/10 minutes at 230° C./2.16 kg,
which are present in the mixture in an amount of 20 to 90% by weight of the elastomeric polyolefins or elastomeric styrene ethylene butadiene terpolymers
B2) olefin copolymers of 50 to 95% by weight of ethylene and 50 to 5% by weight of propylene and/or &agr;-olefins with 4 to 18 carbon atoms and/or ethylenically unsaturated carboxylate esters of the vinyl acetate type and/or C
1
to C
8
alkyl (meth)acrylates with melt indexes of 0.2 to 30 g/10 minutes at 190° C./2.16 kg, and/or
B3) largely amorphous polypropylenes or propylene copolymers with a crystalline polypropylenes or crystalline propylene copolymers content of less than 10% by weight, an enthalpy of melting of less than 40 J/g and a melt index of 0.1 to 40 g/10 minutes at 230° C./2.16 kg, the elastomeric, largely amorphous polypropylene being a homopolymer of propylene and/or a copolymer of propylene of at least 80 mole percent propylene and not more than 20 mole percent of one or more &agr;-olefins of the general formula CH
2
=CHR, wherein R is a linear or branched alkyl group with 2 to 8 carbon atoms, and/or
B4) non-isotactic propylene homopolymers with a melting point of 145° to 165° C., a melt viscosity of more than 200,000 g/m/sec at 190° C.,

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