Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-07-31
2004-09-14
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C264S494000, C264S496000, C522S033000, C522S039000, C522S040000, C522S044000, C522S046000, C522S055000, C522S064000, C522S074000, C522S076000, C522S078000, C522S079000, C522S080000, C522S081000, C522S083000, C522S112000, C522S114000, C522S121000, C525S074000, C525S078000, C525S079000, C525S080000
Reexamination Certificate
active
06790874
ABSTRACT:
TECHNICAL FIELD
This invention relates to thermoplastic, polyolefin materials (“polyolefins”) having superior mar, scratch, wear, and abrasion resistance and methods of making such polyolefins by exposure to radiation to crosslink unsaturated polyolefins therein.
BACKGROUND OF THE INVENTION
Polyolefins are useful in a wide variety of applications due to their strength, environmental resistance and moldability. Many polyolefins are too easily scratched, marred, worm, abraded or otherwise damaged on their surface. These surface characteristics may be measured in a variety of ways. For example, scratch resistance may be measured by vertically penetrating a scratch needle, with a spherical tip into a polyolefin or other material surface under a constant load. The needle is then moved horizontally at a constant rate, and the width and/or depth of any formed scratch is measured (See, e.g., T. Nomura, et al.,
J. Applied Polymer Sci
. 55:1307-1315 (1995)). Generally, it has been desired to enhance the service life of a polyolefin by improving these surface characteristics to reduce scratching, marring, wearing, abrasion, and the like.
One conventional method to enhance surface characteristics has been to use inorganic particulate material, such as various silicas. 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, toughness, processability, and the like.
A more effective conventional method of providing surface enhancing characteristics to certain polyolefins is disclosed in U.S. Pat. No. 4,921,669. This patent discloses passing a web of extruded thermoplastic synthetic resin through a polishing roll stack, wherein at least one of the rolls has thereon a film of a material forming such a scratch resistant coating that is transferred from the roll to the web surface. Such conventional methods of enhancing the surface characteristics of a polyolefin require expensive, bulky equipment that also increase the processing time of polyolefin products.
Another way 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 m. The surface altering agent is preferably prepared by an endopolymerization, which is used with a compatible polyolefin to be altered.
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 (“UV”). The following patents describe a variety of examples of such conventional “apply coating and cure” methods and compositions.
U.S. Pat. Nos. 4,153,526 and 4,039,720 disclose safety glass made by laminating a saturated polyvinyl acetal film and a photoinitiator to a ply of glass, and irradiating the film with UV to initiate crosslinking and to provide improved solvent-abrasion resistance. U.S. Pat. No. 4,227,979 discloses radiation-curable coating compositions including one or more amide acrylate compounds that form mar-resistant protective and decorative film coatings.
U.S. Pat. No. 4,255,303 discloses a composition for coating electrical applications including ethylene polymer and at least 10 parts by weight of talc filler per 100 parts by weight of polymer, where the talc is coated with at least one metallic salt of a fatty acid having 8 to 20 carbon atoms. The ethylene polymers may be curable by irradiation with high-energy electron beams or a chemical curing agent, such as organic peroxide. U.S. Pat. No. 4,371,566 discloses actinic radiation curable coating compositions for application to many substrates having a pentaerythritol-based polyacrylate or polymethacrylate, such as pentaerythritol tetraacrylate, a vinyl chloride-vinyl acetate containing polymer, and a photoinitiator, preferably applied by spraying a solution onto the substrate.
U.S. Pat. No. 4,478,876 discloses a process of coating a solid substrate with an abrasion resistant silicone hard coating curable upon UV exposure under a non-inert atmosphere, such as air. The composition includes a UV crosslinkable polyfunctional acrylate monomer, SiO
2
in the form of colloidal silica, and acryloxy functional silanes and a selected blend of ketone-type and hindered amine-type photoinitiators.
U.S. Pat. No. 4,814,207 discloses a method for applying a scratch and weather resistant film coating to a shaped article by applying to the article a thin film of a mixture of free radically polymerizable monomer having at least two polymerizable olefinic bonds, a peroxide initiator having a half life of less than two minutes at 100° C., and an ultraviolet stabilizer, and curing the film by heating it to a temperature greater than 70° C. U.S. Pat. No. 4,902,578 discloses a radiation-curable coating for thermoplastic substrates having a polyfunctional acrylic monomer, a mono-, di-, or trifunctional acrylic monomer, a thermoplastic or elastomeric polymer, and a photoinitiator.
U.S. Pat. No. 5,006,436 discloses a UV curable, aqueous alkaline developable solder mask composition having a thermal free radical initiator capable of generating free radicals with heat, and a polyunsaturated compound capable of being thermally crosslinked by the free radicals to provide a substantially fully cured coating. U.S. Pat. No. 5,316,791 discloses a process for improving the impact resistance of a coated plastic substrate by applying an aqueous polyurethane dispersion as a primer layer, partially curing the layer by air drying, applying a coating composition over the primer layer, and curing the coating composition to form an abrasion-resistant hard coat. U.S. Pat. No. 5,382,604 discloses a crosslinked adhesive composition having an epoxidized diolefin block polymer crosslinked by UV radiation through at least some of the epoxy functionality.
U.S. Pat. No. 5,558,911 discloses a method of coating articles with powder coatings having polymers applied to the substrate to be coated, melting the polymers, and crosslinking by UV radiation.
U.S. Pat. No. 5,591,551 discloses a lithographic coating and method of coating at least a portion of a surface allow of an article with a radiation-crosslinkable polymer and exposing it to a pattern of radiation to produce an image. The polymer is disclosed to be a copolymer of an isoolefin of 4-7 carbon atoms and para-alkylstyrene.
U.S. Pat. No. 5,618,586 discloses self-crosslinkable film-forming compositions as coatings and a process for preparing multi-layered coated articles with a colored base coat and a clear top coat, wherein the composition includes a non-gelled addition polymer that is the free radical initiated reaction product of an N-alkoxymethyl(meth)acrylamide and at least one other ethylenically unsaturated monomer.
These conventional curable products generally require several steps, particularly coating or effectively laminating a prepared product with the V-curable coating. However, it would be advantageous to provide independent polyolefin compositions that are capable of being cured without the need for additional processing steps, such as coating or laminating an article with a curable composition. It is thus desired to produce such a product, preferably one having enhanced surface durability. The present invention provides new polyolefin compositions that satisfy this need.
SUMMARY OF THE INVENTION
The present invention relates to a thermoplastic polyolefin composition having enhanced surface durability, which includes a base component of a thermoplastic polyolefin, at least one radiation-crosslinkable component present in an amount sufficient to enhance th
Capocci Gerald
Chang Chia-Hu
DeBellis Anthony
Horsey Douglas
Lau Edmund K.
Solvay Engineered Polymers
Wenderoth , Lind & Ponack, L.L.P.
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