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
2000-09-29
2002-06-11
Nutter, Nathan M. (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...
C525S201000, C525S216000, C525S232000, C525S240000, C525S241000
Reexamination Certificate
active
06403721
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to polyolefin blends having superior physical properties including enhanced scratch resistance, rigidity, and toughness. The invention also relates to the process of manufacturing such polyolefin blends and to articles produced from such polyolefin blends.
BACKGROUND ART
In numerous applications, such as many in the automotive industry, a polymeric material that exhibits a good level of scratch resistance balanced with rigidity and impact toughness is desired. These properties tend to vary, however, such that efforts to enhance one will often result in deterioration of one, or both, of the others.
Polypropylene blends are useful in a wide variety of applications due to their strength, environmental resistance and processability. While highly crystalline polypropylene does exhibit good mar and scratch resistance, it does not possess the impact toughness required in many important applications such as the making of automobile parts. Special polymeric materials have been developed that overcome this problem to some degree.
Attempts to remedy polypropylene's deficiency in impact toughness by blending with impact modifying copolymers of ethylene and other alpha-olefins, terpolymers of ethylene, other alpha-olefins, and dienes have not been completely successful. Elastomer modified polypropylene blends, also known as thermoplastic polyolefins, have the advantage of improved toughness, especially for cold temperature impact. They are widely used for formed or shaped articles such as automotive parts, toys, furniture, and housing products. Although the impact toughness of those compositions is improved by these modifiers, the scratch resistance has been found to decrease. That is, the scratch resistance of polypropylene blends containing impact modifiers such as ethylene-propylene copolymers, ethylene-propylene terpolymers, ethylene-butene copolymers, or ethylene-octene copolymers is poor.
Increasing the crystallinity of the polypropylene to obtain a harder surface, and/or adding hard mineral filler to these blends, has been attempted as a countermeasure without complete success. One conventional method to enhance surface characteristics is to use inorganic particulate material. Uniform dispersion of these particulates is difficult to achieve, however, and this results in non-uniform surface properties in such products. The use of these particulates also tends to damage other desirable physical properties of the polyolefin, resulting in loss of impact strength and/or toughness. Debonding of these particulates from the polyolefin system, also contributes to stress whitening, which is not desirable.
Another conventional way to enhance surface characteristics of various articles is to apply acrylic polymers or coatings to an article and subsequently cure the polymer or coating with a radiation source, such as ultraviolet radiation.
A method to enhance surface characteristics of polyolefins is described in U.S. Pat. No. 4,000,216 , which discloses an extrudable, moldable, or heat formable blend of a thermoplastic polymer and a surface altering agent of at least one monoethylenically unsaturated monomer for said thermoplastic polymer, wherein the surface altering agent has cross-linked polymer particles having an average size of 1 to 30 microns. The surface altering agent is preferably prepared by an endopolymerization, which is used with a compatible polyolefin to be altered.
European Patent Application 0794225A1 describes thermoplastic resin compositions comprising polypropylene, a styrene containing elastomer, and talc, and having an acceptable balance of toughness and rigidity. The disclosure stresses the importance of the proportions of each component used to achieve this balance. In PCT Application WO97/38050 , a similar balance of properties is reported for a thermoplastic resin comprising an ethylene-propylene based polymer composition, an ethylene/alpha-olefin copolymer based rubber and/or a rubber containing vinyl aromatic compounds and talc. Another example of a composition that provides an acceptable balance of toughness and rigidity is reported in Japanese Patent Application 10219040A for a resin composition consisting of a polyolefin based resin and a block copolymer based on aromatic vinyl and butadiene monomer units. Polymer blends which can be formed or shaped into lightweight and durable articles useful, for example, as automobile parts, toys, housings for various types of equipment, and the like, are well known in the art.
The physical and/or chemical properties of the thermoplastic polyolefin blends can be modified either by blending them with other thermoplastic polymers, or by incorporating into them materials having one or more polar groups, or both. For example, U.S. Pat. No. 4,946,896 describes a thermoplastic polyolefin comprising 20-80 weight percent polypropylene; 5-38 weight percent of an ethylene copolymer consisting of ethylene, an ester unit of either alkyl acrylate or methacrylate, and an unsaturated dicarboxylic acid anhydride; and 5-70 weight percent ethylene-propylene rubber. Similarly, U.S. Pat. No. 4,888,391 describes a polyolefin composition comprising a blend of a polyolefin as the continuous phase with an ethylene/acrylate/acrylic acid terpolymer as a discontinuous phase. These polyolefin-based blends are paintable.
Despite these prior art formulations, there remains a need to obtain polymeric materials which have a good level of mar/scratch resistance along with the physical property requirements of rigidity, strength, processability, and low temperature impact toughness. The present invention provides certain blends that meet these needs.
SUMMARY OF THE INVENTION
The present invention relates to polyolefin blends that have excellent scratch and mar resistance, rigidity, and toughness.
In one embodiment the blends contain: a first component of a first propylene containing polymer; a second component of a propylene-based polyolefin-metal salt that is a reaction product of a second propylene-containing polymer and a first organic monomer containing a hydrophilic moiety that is at least partially neutralized with a metal ion, and/or a copolymer of propylene and a first organic monomer containing a hydrophilic moiety that is at least partially neutralized with a metal ion; and a third component of an ethylene-based polyolefin-metal salt that is a reaction product of an ethylene-containing polymer and a second organic monomer and contains a hydrophilic moiety that is at least partially neutralized with a metal ion, and/or an ionomer that is at least partially neutralized with a metal ion.
The polyolefin blend may contain about 50 percent to about 75 percent of propylene polymers; about 1 percent to about 30 percent of propylene-based polyolefin-metal salts; and about 5 percent to about 49 percent of ethylene-based polyolefin-metal salts. Preferably, the polyolefin blend contains about 53 percent to about 70 percent of the propylene polymers; about 4 percent to about 20 percent of the propylene-based polyolefin-metal salts; and about 15 percent to about 35 percent of the ethylene-based polyolefin-metal salts. Even more preferably, the polyolefin blend contains about 57 percent to about 68 percent of propylene polymers; about 5 percent to about 15 percent of the propylene-based polyolefin-metal salts, and about 20 percent to about 30 percent of the ethylene-based polyolefin-metal salts.
The polyolefin-metal salts may include a polyolefin backbone functionalized with at least about 0.3 percent, preferably at least 0.5 percent, of hydrophilic organic compounds based on the combined weight of the polyolefin and the hydrophilic organic compounds. In some embodiments the polyolefin-metal salts may include a random copolymer of ethylene with an ethylenically unsaturated carboxylic acid, which is subsequently neutralized with a metal salt. Such a compound is commonly called an ionomer. In a preferred embodiment, the polyolefin-metal salts are comprised of an inert polyolefin, for example polypropylene, polyethyl
Ding Rui-dong
Lau Edmund K.
Srinivasan Satchit
Nutter Nathan M.
Solvay Engineered Polymers
Winston & Strawn
LandOfFree
Engineered polyolefin materials with enhanced surface... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Engineered polyolefin materials with enhanced surface..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Engineered polyolefin materials with enhanced surface... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2952765