Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-01-20
2002-09-17
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S504000, C524S567000
Reexamination Certificate
active
06451882
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to compositions comprising acrylonitrile/styrene/acrylic (“ASA”) polymeric materials and wood, and to methods for making such compositions. More particularly, the present invention relates to compositions comprising ASA polymeric materials and wood which include physical mixtures of ASA polymers and wood and to methods for making such physical mixture-containing compositions.
ASA polymeric materials are known and have been used in various applications which have taken advantage of the weatherability of such materials. As used herein, the term “weatherability” refers to the ability or property of a material to effectively withstand the conditions of an out-of-doors environment over a long period of time, for example, at least five years and preferably at least seven years, with substantially no degradation or decomposition.
ASA polymeric materials that have been taught include, for example, those disclosed in Yu in U.S. Pat. No. 3,994,631, which provides a multi-stage interpenetrating interpolymer. These ASA polymeric materials provide for excellent weatherability. Additionally, Ting U.S. Pat. Nos. 4,731,414 and 4,831,079 and Aliberto et al. U.S. Pat. No. 4,517,339 disclose that other additives may be blended with ASA interpolymers to achieve better optical quality, impact resistance, and fire retardancy. Other patents, for example, Walker et al U.S. Pat. No. 4,537,933 and Morinaga et al, U.S. Pat. No. 4,151,226 disclose ASA polymeric materials including terpolymers, such as styrene acrylonitrile polymers to which are grafted acrylate and/or methacrylate polymers. The disclosure of each of these patents is incorporated in its entirety herein by reference.
Although wood is commonly used as a material of construction because of its strength, look and texture, it has the substantial disadvantage of being not very weatherable. None of the above-noted patents even suggest the use of wood in combination with ASA polymeric materials.
It would be advantageous to provide a component having one or more of the aforementioned weatherability properties and a wood-like look and texture for many applications.
SUMMARY OF THE INVENTION
New acrylonitrile/styrene/acrylic polymeric material, wood component-containing compositions and methods for making such compositions have been discovered. The present invention is based on the discovery that acrylonitrile/styrene/acrylic (ASA) polymeric materials, however produced, can be physically blended together with wood in a single step, for example, using methodologies which can be cost effectively practiced to provide ASA polymeric material, wood component-containing compositions which have controlled and substantially uniform compositions or make-ups. One advantage of the present invention is that the compositions can be fabricated into products which have a wood-like look and texture, derived at least in part from the wood component included in the compositions. Moreover, the present compositions advantageously have desirable properties, for example, weatherability, strength, flexibility and the like, of the ASA polymeric materials included in the compositions.
In a broad aspect of the present invention, weatherable compositions are provided which comprise an ASA polymeric material and a wood component in an amount effective as a filler in the compositions. The ASA polymeric material preferably is present in an amount in the range of about 30% or about 40% to about 99.5%, more preferably about 60% to about 99%, based on the total weight of the composition. The wood preferably is present in the present weatherable compositions in an amount in a range of about 0.5% to about 60% or about 70%, more preferably about 1% to about 40%, based on the total weight of the composition. Although the wood component may be present in any suitable form, it is preferred that the wood be present as wood particles, such as wood chips, wood flakes, sawdust, wood flour, and the like and mixtures thereof. More preferably, such particles have a size in the range of about 40 to about 200 U.S. mesh, still more preferably, about 50 to about 150 U.S. mesh.
In one embodiment of the present invention, compositions are provided which comprise a substantially uniform blend of an uncrossed-linked acrylonitrile/styrene copolymer, for example, a linear uncross-linked acrylonitrile/styrene copolymer, an acrylate copolymer, such as a cross-linked alkyl acrylate/graft (meth)acrylate copolymer, and filler, for example, wood component particles. Wood is a preferred filler component because it is weatherable and, in addition, may be used to provide an aesthetically pleasing wood-like look and/or texture to the outer surface of the final product, e.g., housing siding, structural members and the like, including the present compositions.
In one particularly useful embodiment of the present invention, weatherable compositions are provided which comprise a substantially uniform blend including (1) a physical mixture of at least about 30% by weight, based on the total weight of the physical mixture, of an uncrossed-linked acrylonitrile/styrene copolymer and at least about 5% by weight, based on the total weight of the physical mixture of a cross-linked alkyl acrylate/graft (meth)acrylate copolymer; and (2) a wood component in an amount effective as a filler in the composition.
Without wishing to limit the invention to any particular theory of operation, it is believed that the uncross-linked (e.g., linear) acrylonitrile/styrene copolymer is substantially miscible or compatible with the (meth)acrylate of the cross-linked alkyl acrylate/graft (meth)acrylate copolymer at effective blending conditions. Thus, during the blending operation, the two copolymer components can be combined with the filler component into a substantially uniform combination even though the cross-linked alkyl acrylate may not be miscible or compatible with the uncross-linked acrylonitrile/styrene copolymer. In other words, the (meth)acrylate appears to mitigate against the incompatibility between the uncross-linked acrylonitrile/styrene copolymer and the cross-linked alkyl acrylate. The cross-linked alkyl acrylate/graft (meth)acrylate copolymer provides the acrylic portion of the present ASA polymeric material, wood-containing compositions and, in addition, facilitates the formation of the present substantially uniform, preferably physical, mixtures of copolymers. Moreover, the cross-linked alkyl acrylate/graft (meth)acrylate copolymer is effective to provide beneficial impact resistance to the present compositions.
In order to avoid component incompatibility, the present compositions preferably are substantially free of cross-linked acrylonitrile/styrene copolymers.
As used herein, the terms “physical blend” or “physical mixture” refers to a composition in which the constituent components are combined or mixed with substantially no chemical bonding, in particular with substantially no covalent chemical bonding between the constituents.
The uncross-linked acrylonitrile/styrene copolymers preferably are present in amounts in a range of about 30% to about 95% by weight of the copolymers present. The cross-linked alkyl acrylate/graft (meth)acrylate copolymers preferably are present in amounts in a range of about 5% to about 70% by weight of the copolymers present.
As noted above, it has been found that ASA polymeric materials, however produced, can be effectively blended with wood components, for example, wood particles, to produce compositions having advantageous properties and/or applications.
For example, one type of ASA polymeric material useful in the present compositions is in the form of one or more interpolymers. Such interpolymers preferably are formed from styrene, acrylonitrile and at least one component selected from the group consisting of acrylates, methacrylates and mixtures thereof. The presently useful interpolymers more preferably comprise a crosslinked alkyl (meth)acrylate polymer, crosslinked styrene acrylonitrile polymer and an uncrosslinked styrene-acr
Hughes Processing, Inc.
Stout, Uxa Buyan & Mullins, LLP
Uxa Frank J.
Yoon Tae H.
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