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
2001-04-16
2004-08-31
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...
C525S222000, C525S223000, C525S236000, C525S240000, C525S241000, C526S290000, C526S318000, C526S318400, C526S318410, C526S318430, C526S319000, C526S326000, C428S500000
Reexamination Certificate
active
06784249
ABSTRACT:
BACKGROUND OF THE INVENTION
Automotive instrument panels and door panels are typically composites which are made of a rigid backing which supports a semi-rigid urethane foam with the semi rigid urethane foam being covered with a skin compound. Such skin compounds are typically blends of polyvinyl chloride (PVC) with a nitrile rubber (NBR). The nitrile rubber is included in such blends as a permanent modifier for the PVC that provides it with a higher degree of flexibility.
The automotive industry is continuing to move toward more aerodynamic body designs that typically include larger glass areas. Such design changes have significantly increased the heat and ultraviolet light aging requirements of automotive interiors. This has in turn significantly increased the demands put upon the polymers that are utilized as skins in automotive interior panels.
Heat and light stabilizers can be employed to improve the heat and ultraviolet light aging characteristics of conventional PVC/NBR blends that are utilized as skins for automotive interior panels. However, the degree to which the aging characteristics of such blends can be improved by the addition of additives is limited. In fact, there is a demand for performance characteristics in such applications that heretofore has not been realized by the utilization of heat and light stabilizers. For instance, it would be highly desirable for the skins used in automotive panels to resist discoloration and cracking under conditions of high heat and intense ultraviolet light throughout the life of the vehicle.
NBR/PVC blends offer an array of physical properties that make them useful as a skin composition for automotive panels. The NBR acts as a permanent flexibilizing monomer for the PVC. It also acts as a shrinkage control agent, and embossing aid, and improves grain retention. The NBR in such blends further provides vacuum forming gauge control and exhibits low fog characteristics. NBR is highly compatible with PVC and has the capability of being recycled. It is essential for any polymer that is substituted for NBR to display these essential characteristics.
U.S. Pat. No. 5,415,940 discloses a rubbery polymer that can be blended with PVC to make leathery compositions that are particularly useful in automotive applications by virtue of their high level of heat and ultra-violet light resistance. The rubbery polymers disclosed by U.S. Pat. No. 5,415,940 is comprised of repeat units which are comprised of (a) butyl acrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a half ester maleate soap, and (f) a crosslinking agent.
SUMMARY OF THE INVENTION
There is a growing demand being made by the automotive and other industries for halogen-free materials. The present invention relates to a rubbery polymer that can be blended with polyolefins, such as polyethylene or polypropylene, to make leathery compositions that exhibit a high level of resistance to heat and ultra-violet light. These compositions are particularly useful in manufacturing skins for automotive interior paneling. Skin compositions that are made utilizing this rubbery polymer provide a higher level of resistance to heat and ultraviolet light than those made utilizing conventional NBR/PVC blends. The rubbery polymer compositions of this invention also offer low fog characteristics, low odor, shrinkage control, and grain retention. They also act as an embossing aid and as a permanent flexibilizing modifier. The rubbery polymers of this invention also have characteristics that make them useful in building gasket applications.
This invention more specifically discloses a rubbery polymer that can be blended with polyolefins to make leathery compositions having good heat and ultraviolet light resistance, said rubbery polymer being comprised of repeat units which are derived from (a) butyl acrylate, (b) an alkoxyalkylene acrylate, (c) styrene, (d) a half ester maleate soap, and (e) a crosslinking agent.
The present invention also discloses a leathery composition which is useful in automotive applications which is comprised of (1) a polyolefin, (2) a plasticizer, and (3) a rubbery polymer which is comprised of repeat units which are derived from (a) butyl acrylate, (b) an alkoxyalkylene acrylate, (c) styrene, (d) a half ester maleate soap, and (e) a crosslinking agent.
The subject invention further reveals a panel for automotive applications which is comprised of a semirigid urethane foam which is supported by a rigid backing, wherein said semirigid urethane foam is covered with a leathery skin which is comprised of (1) polyolefin, (2) a plasticizer, and (3) a rubbery polymer which is comprised of repeat units which are derived from (a) butyl acrylate, (b) an alkoxyalkylene acrylate, (c) styrene, (d) a half ester maleate soap, and (e) a crosslinking agent.
DETAILED DESCRIPTION OF THE INVENTION
The rubbery polymers of this invention are synthesized utilizing a free radical emulsion polymerization technique. These rubbery polymers are comprised of repeat units which are derived from (a) butyl acrylate, (b) an alkoxyalkylene acrylate, (c) styrene, (d) a half ester maleate soap, and (e) a crosslinking agent. The crosslinking agent is typically a multi-functional acrylate, a multi-functional methacrylate or divinylbenzene. Some specific examples of crosslinking agents that can be used include ethylene glycol methacrylate, divinylbenzene, and 1,4-butanediol dimethacrylate.
Technically, the rubbery polymers of this invention contain repeat units (chain linkages) that are derived from (a) butyl acrylate, (b) an alkoxyalkylene acrylate, (c) styrene, (d) a half ester maleate soap, and (e) a crosslinking agent. These repeat units differ from the monomers that they were derived from in that they contain one less carbon-carbon double bond than is present in the respective monomer. In other words, a carbon-to-carbon double bond is consumed during the polymerization of the monomer into a repeat unit in the rubbery polymer. Thus, in saying that the rubbery polymer contains various monomers in actuality means that it contains repeat units that are derived from those monomers.
The rubbery polymers of this invention will normally contain (a) about 30 to about 65 weight percent butylacrylate, (b) from about 30 to about 65 weight percent of the alkoxyalkylene acrylate, (c) from about 3 to about 25 weight percent styrene, (d) from about 1 weight percent to about 5 weight percent of a half ester maleate soap, and (e) from about 0.25 to about 8 weight percent crosslinking agent. Such rubbery polymers will preferably contain (a) from about 40 weight percent to about 54 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate, (b) from about 40 to about 54 weight percent of the alkoxyalkylene acrylate, (c) from about 5 weight percent to about 18 weight percent styrene, (e) from about 1 weight percent to about 5 weight percent of a half ester maleate soap, and (f) from about 0.5 weight percent to about 4 weight percent of a crosslinking agent. The rubbery polymers of this invention will more preferably be comprised of repeat units which are derived from (a) from about 42 weight percent to about 47 weight percent butyl acrylate, or optionally a mixture of butyl acrylate and 2-ethylhexyl acrylate containing up to about 40% 2-ethylhexyl acrylate, (b) from about 42 to about 47 weight percent of the alkoxyalkylene acrylate, (c) from about 8 weight percent to about 14 weight percent styrene, (d) from about 2 weight percent to about 4 weight percent of a half ester maleate soap, and (e) from about 1 weight percent to about 3 weight percent of a crosslinking agent. The percentages reported in this paragraph are based upon the total weight of the rubbery polymer.
The rubbery polymers of the present invention are synthesized in an aqueous reaction mixture by utilizing a free radical polymerization technique. T
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