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
1998-12-17
2001-01-23
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...
C525S064000, C525S078000
Reexamination Certificate
active
06177515
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to compositions comprising a graft copolymer of a propylene polymer material, to which one or more vinyl monomers are graft polymerized.
BACKGROUND OF THE INVENTION
Molded articles made from polyolefins tend to have poor scratch and mar resistance. That is, the surface is easily marred or scratched by lightly rubbing with an object such as a fingernail. Articles made from modified polyolefins, for example, propylene polymer materials grafted with one or more vinyl monomers such as styrene and acrylic compounds, also exhibit poor scratch and mar resistance. When rubber is added to these graft copolymers, the scratch and mar resistance of articles made therefrom usually deteriorate.
The scratch and mar resistance of thermoplastic olefins, which are uncrosslinked blends of crystalline olefin polymers and olefin polymer elastomers, was improved by adding a lubricant such as a polysiloxane, either alone or in combination with an aliphatic amide such as erucamide and/or oleamide, as disclosed in European Patent Application 832,925.
There is a need for improving the scratch and mar resistance of a graft copolymer comprising a backbone of a propylene polymer material to which are grafted polymerized vinyl monomers, while still maintaining a good balance of mechanical properties and high surface gloss.
SUMMARY OF THE INVENTION
The composition of this invention comprises (1) a graft copolymer comprising a backbone of a propylene polymer material having graft polymerized thereto at least one vinyl monomer capable of being polymerized by free radicals, wherein the polymerized monomers are present in an amount of about 10 to about 120 parts per hundred parts of the propylene polymer material, and (2) an additive selected from the group consisting of (a) about 0.5% to about 10% of at least one low molecular weight ethylene polymer or a functionalized derivative thereof having a number average molecular weight of about 300 to about 5000, and (b) a combination of (i) about 0.5% to about 10% of at least one of the low molecular weight ethylene polymers in (a) and (ii) about 0.5% to about 10% of inorganic microspheres, based on the total weight of the composition. Optionally the composition can also contain a coupling agent such as an unsaturated carboxylic acid-functionalized propylene polymer.
The composition optionally contains about 2% to about 30% of one or more rubber components, about 15% to about 50% of a broad molecular weight distribution propylene polymer material, or a combination of the two.
Molded articles made from these compositions have a glossy surface that is much more resistant to scratching and marring than typical graft copolymers of the type described above.
DETAILED DESCRIPTION OF THE INVENTION
Component (1) of the composition of this invention is a graft copolymer, comprising a backbone of a propylene polymer material having graft polymerized thereto at least one vinyl monomer capable of being polymerized by free radicals.
The propylene polymer material that is used as the backbone of the graft copolymer can be:
(1) a homopolymer of propylene having an isotactic index greater than 80, preferably about 85 to about 99;
(2) a copolymer of propylene and an olefin selected from the group consisting of ethylene and 4-10 C alpha-olefins, provided that when the olefin is ethylene, the maximum polymerized ethylene content is about 10%, preferably about 4%, and when the olefin is a 4-10 C alpha-olefin, the maximum polymerized content thereof is about 20% by weight, preferably about 16%, the copolymer having an isotactic index greater than 85;
(3) a terpolymer of propylene and two olefins selected from the group consisting of ethylene and 4-8 C alpha-olefins, provided that the maximum polymerized 4-8 C alpha-olefin content is 20% by weight, preferably about 16%, and, when ethylene is one of the olefins, the maximum polymerized ethylene content is 5% by weight, preferably about 4%, the terpolymer having an isotactic index greater than 85;
(4) an olefin polymer composition comprising:
(a) about 10% to about 60% by weight, preferably about 15% to about 55%, of a propylene homopolymer having an isotactic index greater than 80, preferably about 85 to about 98, or a copolymer of monomers selected from the group consisting of (i) propylene and ethylene, (ii) propylene, ethylene and a 4-8 C alpha-olefin, and (iii) propylene and a 4-8 C alpha-olefin, the copolymer having a polymerized propylene content of more than 85% by weight, preferably about 90% to about 99%, and an isotactic index greater than 85;
(b) about 5% to about 25% by weight, preferably about 5% to about 20%, of a copolymer of ethylene and propylene or a 4-8 C alpha-olefin that is insoluble in xylene at ambient temperature; and
(c) about 30% to about 70% by weight, preferably about 40% to about 65%, of an elastomeric copolymer of monomers selected from the group consisting of (i) ethylene and propylene, (ii) ethylene, propylene, and a 4-8 C alpha-olefin, and (iii) ethylene and a 4-8 C alpha-olefin, the copolymer optionally containing about 0.5% to about 10% by weight of a polymerized diene and containing less than 70% by weight, preferably about 10% to about 60%, most preferably about 12% to about 55%, of polymerized ethylene and being soluble in xylene at ambient temperature and having an intrinsic viscosity, measured in tetrahydronaphthalene at 135° C., of about 1.5 to about 4.0 dl/g,
wherein the total amount of (b) and (c), based on the total olefin polymer composition, is about 50% to about 90%, the weight ratio of (b)/(c) is less than 0.4, preferably 0.1 to 0.3, and the composition is prepared by polymerization in at least two stages and has a flexural modulus of less than 150 MPa; or
(5) a thermoplastic olefin comprising:
(a) about 10% to about 60%, preferably about 20% to about 50%, of a propylene homopolymer having an isotactic index greater than 80, or a copolymer of monomers selected from the group consisting of (i) ethylene and propylene, (ii) ethylene, propylene and a 4-8 C alpha-olefin, and (iii) ethylene and a 4-8 C alpha-olefin, the copolymer having a polymerized propylene content greater than 85% and an isotactic index of greater than 85;
(b) about 20% to about 60%, preferably about 30% to about 50%, of an amorphous copolymer from monomers selected from the group consisting of (i) ethylene and propylene, (ii) ethylene, propylene, and a 4-8 C alpha-olefin, and (iii) ethylene and a 4-8 C alpha-olefin, the copolymer optionally containing about 0.5% to about 10% of a polymerized diene, and containing less than 70% polymerized ethylene and being soluble in xylene at ambient temperature; and
(c) about 3% to about 40%, preferably about 10% to about 20%, of a copolymer of ethylene and propylene or a 4-8 C alpha-olefin that is insoluble in xylene at ambient temperature,
wherein the thermoplastic olefin has a flexural modulus of greater than 150 but less than 1200 MPa, preferably about 200 to about 1100 MPa, and most preferably about 200 to about 1000 MPa.
Room or ambient temperature is ~25° C.
The 4-8 C alpha-olefins useful in the preparation of (4) and (5) include, for example, butene-1, pentene-1; hexene-1; 4-methyl-1-pentene, and octene-1.
The diene, when present, is typically a butadiene; 1,4-hexadiene; 1,5-hexadiene, or ethylidenenorbornene.
Propylene polymer materials (4) and (5) can be prepared by polymerization in at least two stages, where in the first stage the propylene; propylene and ethylene; propylene and an alpha-olefin, or propylene, ethylene and an alpha-olefin are polymerized to form component (a) of (4) or (5), and in the following stages the mixtures of ethylene and propylene; ethylene and the alpha-olefin, or ethylene, propylene and the alpha-olefin, and optionally a diene, are polymerized in the presence of (a) to form components (b) and (c) of (4) or (5).
The polymerization can be conducted in liquid phase, gas phase, or liquid-gas phase using separate reactors, all of which can be done either by batch or continuously. For example, it is
Berta Dominic A.
Khasat Nitya P.
Rosenthal Jay S.
Smith Jeanine A.
Asinovsky Olga
Montell Technology Company BV
Seidleck James J.
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