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
2000-01-20
2002-09-10
Mullis, Jeffrey (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...
C525S069000, C525S070000, C525S071000, C525S078000, C525S080000, C525S086000, C525S087000
Reexamination Certificate
active
06448332
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to compositions comprising acrylonitrile/styrene/acrylic (“ASA”) polymeric materials and to methods for making such compositions. More particularly, the invention relates ASA polymeric materials which have one or more enhanced properties, such as impact resistance.
ASA polymeric materials are known and have been used in various applications which have taken advantage of the excellent properties, for example, 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 include, for example, those disclosed in Kakefuda et al U.S. Pat. No. 3,711,575, which provides an ASA terpolymer, prepared by grafting acrylate to styrene/acrylonitrile copolymer. Although such ASA terpolymers have good weatherability, they are difficult and cumbersome to produce.
Yu U.S. Pat. No. 3,994,631, disclosed a method for forming an ASA interpolymer wherein the acrylic polymers interpenetrate a web of styrene/acrylonitrile copolymers through sequence emulsion polymerization. This method, although it does not require grafting, does involve sequential polymerizations.
Recently, Hughes U.S. Pat. No. 5,883,191 disclosed a method of forming an ASA composition with excellent properties by physically mixing styrene/acrylonitrile copolymers and acrylate polymers. No grafting or sequential polymerizations are required.
There continues to be a need in the industry for ASA polymeric materials, particularly ASA materials in which the acrylic polymer is not chemically or covalently bonded to the styrene/acrylonitrile copolymer, to have better physical properties, such as better impact resistance properties.
SUMMARY OF THE INVENTION
New acrylonitrile/styrene/acrylic polymeric material-containing compositions and methods for making such compositions have been discovered. The present invention is based, at least in part, on the discovery that acrylonitrile/styrene/acrylic (ASA) polymeric materials in which the acrylic polymers are not chemically or covalently bonded to the styrene/acrylonitrile copolymers, for example, including ASA interpolymers and/or physical mixture of styrene/acrylonitrile copolymers and (meth)acrylate polymers, can be physically blended with certain impact modifiers in a single step, for example, using methodologies which can be cost effectively practiced to provide compositions having controlled and substantially uniform compositions or make-ups with enhanced impact resistance properties.
The present invention is particularly advantageous with ASA polymeric materials which are physical mixtures of styrene/acrylonitrile copolymers and acrylate/methacrylate ((meth)acrylate) polymers, such as described in Hughes U.S. Pat. No. 5,883,191, the disclosure of which is incorporated in its entirety herein by reference. This is so because the final material has enhanced properties, for example, enhanced impact resistance, and can be produced by straightforward physical mixing or blending and without one or more relatively complex polymerization steps being required. Control of the make-up and physical properties of such a physically blended ASA polymeric material is more easily achieved than with compositions involving one or more polymerizations.
In one broad aspect of the present invention, weatherable compositions are provided which comprise a first component selected from ASA polymeric materials in which the acrylic polymer is not chemically or covalently bonded to the styrene/acrylonitrile copolymer and a second component or an impact modifier component in an amount effective to enhance the impact resistance of the compositions. The presently useful second or impact modifier components are selected from (A) polymeric materials including units derived from ethylene, units derived from carbon monoxide and units derived from one or more monomers (termonomers) selected from copolymerizable ethylenically unsaturated organic compounds, for example, acrylic acid, acrylic acid esters and the like and mixtures thereof, hereinafter referred to as acrylates, (B) graft polymer components including ethylene-propylene-non-conjugated diene terpolymers grafted with styrene and acrylonitrile monomers, and mixtures thereof. Such impact modifier components are present in the compositions of the present invention in an amount effective to enhance the impact resistance of the composition relative to a substantially identical composition without the impact modifier component. Preferably, the present compositions have increased IZOD values, for example, increased by at least 0.5 ft. lbs./in. notch and preferably at least about 1 or about 2 ft. lbs./in. notch (ASTM D2965-94(97) test at 23° C.) relative to substantially identical compositions without the second or impact modifier component.
The presently useful second or impact modifier components preferably are present in an amount in a range of about 1% to about 20%, more preferably about 3% or about 5% to about 12% or about 15% by weight of the total weight of the first and second components present. Higher concentrations of the impact modifier components, even within the percentage ranges set forth herein, may :not result in compositions having higher impact resistances.
In one particularly useful embodiment of the present invention, compositions are provided which comprise a substantially uniform physical 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 the impact modifier component, as described herein.
Preferably, 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) an impact modifier component, as described herein, in an amount effective to enhance impact resistance in the composition.
In order to avoid component incompatibility within (1) above, 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.
In another broad aspect of the present invention, an ASA interpolymer is blended with an impact modifier component, as described herein, to produce a composition with enhanced impact resistance.
In one particularly useful embodiment of the present invention, the 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-acrylonitrile polymer. The alkyl acrylate polymer, crosslinked styrene acrylonitrile polymer and uncrosslinked styrene-acrylonitrile polymer may be alternating copolymers, random copolymers or block copolymers. Additionally, the alky
Hughes Processing, Inc.
Mullis Jeffrey
Stout, Uxa, Buyan & Mullins
Uxa Frank J.
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