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
1999-09-21
2001-05-29
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...
C525S098000, C525S099000, C524S505000
Reexamination Certificate
active
06239217
ABSTRACT:
BACKGROUND
The present invention relates to syndiotactic vinylaromatic polymer compositions containing impact modifiers. More particularly the present invention relates to such compositions wherein the impact modifier comprises an oil extended elastomeric polyolefin. The compositions may further be modified to incorporate crystal modifiers, compatibilizers, fillers, and optionally reinforcing aids. Surprisingly, according to the present invention, high temperature resistant syndiotactic vinylaromatic polymer compositions can be produced having improved elongation, rigidity and toughness.
SUMMARY OF THE INVENTION
According to the present invention there is provided a composition of matter comprising (based on total composition weight:
A) from 25 to 90 parts by weight of a syndiotactic, vinylaromatic polymer,
B) from 5 to 30 parts by weight of an oil extended, elastomeric polyolefin;
C) from 1 to 10 parts by weight of a compatibilizer comprising a styrene containing block copolymer or a hydrogenated derivative thereof;
D) from 0 to 25 parts by weight of a domain forming rubbery polymer comprising a triblock copolymer of styrene and a conjugated diene or a hydrogenated derivative thereof;
E) from 0 to 5 parts by weight of a nucleator for the syndiotactic, vinylaromatic thermoplastic resin,
F) from 0 to 60 parts by weight of a reinforcing agent, and
G) from 0 to 90 parts by weight of a polyarylene ether or polar group modified polyarylene ether.
The polymeric blend has been found to possess increased elongation properties, especially ultimate elongation or elongation at rupture (Er). In addition, in glass filled compositions, the use temperature is also improved, as measured for example by distortion temperature under load (DTUL). Advantageously, while demonstrating improvement in ultimate elongation and DTUL, the resins of the present invention retain advantageous impact properties and tensile strength properties of resin blends not containing the oil extended elastomeric polyolefin resin.
DETAILED DESCRIPTION OF THE INVENTION
Syndiotactic vinylaromatic polymers especially include syndiotactic polystyrene prepared by coordination polymerization of styrene monomer under conditions to provide a high degree of syndiotacticity. Most highly preferred are those polymers containing greater than 75 percent syndiotacticity at a racemic triad, preferably greater than 95 percent syndiotacticity at a racemic triad. Such polymers are known in the art having been previously disclosed in, for example, U.S. Pat. No. 4,680,353; U.S. Pat. No. 4,959,435; U.S. Pat. No. 4,950,724; and U.S. Pat. No. 4,774,301. Preferred compositions according to the invention comprise from 50 to 90 parts by weight syndiotactic vinylaromatic polymer.
Elastomeric polyolefins include any polymer comprising one or more C
2-20
&agr;-olefins in polymerized form, having Tg less than 25° C., preferably less than 0° C. Examples of the types of polymers from which the present elastomeric polyolefins are selected include homopolymers and copolymers of &agr;-olefins, such as ethylene/propylene, ethylene/1-butene, ethylene/1-hexene or ethylene/1-octene copolymers, and terpolymers of ethylene, propylene and a comonomer such as hexadiene or ethylidenenorbornene. Grafted derivatives of the foregoing rubbery polymers such as polystyrene-, maleic anhydride-, polymethylmethacrylate- or styrene/methyl methacrylate copolymer-grafted elastomeric polyolefins may also be used.
The elastomeric polyolefins are softened by incorporation of an aliphatic oil to extend the polyolefin phase, making it softer and more readily dispersed into the syndiotactic vinyl aromatic polymer phase. The extending oils, also referred to as paraffinic
aphthenic oils, are usually fractions of refined petroleum products having less than about 30 percent by weight of aromatics (by clay-gel analysis) and having viscosities between about 100 and 500 SSU at 100° F. (38° C.). Commercial extending oils include SHELLFLEX® oils, numbers 310, 371 and 311 (which is a blend of 310 and 371), available from Shell Oil Company or Drakeol™, numbers 34 or 35, available from Penreco division of Pennzoil Products Company. The amount of extending oil employed varies from 0.01 to 35.0 percent by weight of the elastomeric polyolefin, preferably from 0.1-25 percent.
Preferred elastomeric polyolefins for use herein are such polymers that are characterized by a narrow molecular weight distribution and a uniform branching distribution. Preferred elastomeric polyolefins are linear or substantially linear ethylene interpolymers having a density from 0.85 to 0.93 g/cm
3
, a melt index from 0.1 to 5 g/10 min, and a polydispersity of from 1.8 to 5. Such polymers are preferably those prepared using a Group 4 metal constrained geometry complex by means of a continuous solution polymerization process, such as are disclosed in U.S. Pat. Nos. 5,272,236 and 5,278,272, the teachings of which are hereby incorporated by reference.
Preferred elastomeric polyolefins have a density of from 0.860 to 0.920 g/cm
3
, more preferably from 0.865 to 0.915 g/cm
3
, and especially less than or equal to 0.910 g/cm
3
. Advantageously, component (B) has a melt index from 0.2 to 3 g/10 min. This provides good processing characteristics, gloss, impact resistance, and environmental stress cracking resistance. At polydispersity values exceeding 5, the mechanical properties and gloss of the molded articles decreases. Preferably, component (B) has a polydispersity of 1.8 to 4, more preferably from 1.8 to 2.5.
All references herein to elements or metals belonging to a certain Group refer to the Periodic Table of the Elements published and copyrighted by CRC Press, Inc., 1989. Also, any reference to the Group or Groups shall be to the Group or Groups as reflected in this Periodic Table of the Elements using the IUPAC system for numbering Groups.
The term “polymer” as used herein refers to a polymeric compound prepared by polymerizing one or more monomers. The generic term polymer thus embraces the term homopolymer, usually employed to refer to polymers prepared from only one monomer, and the term interpolymer as defined hereinafter.
The term “interpolymer” as used herein refers to polymers prepared by the polymerization of at least two different monomers. The generic term interpolymer thus embraces copolymers, usually employed to refer to polymers prepared from two different monomers, and polymers prepared from more than two different monomers.
While describing in the present invention a polymer or interpolymer as comprising or containing certain monomers, it is meant that such polymer or interpolymer comprises or contains polymerized therein units derived from such a monomer. For example, if the monomer is ethylene CH
2
═CH
2
, the derivative of this unit as incorporated in the polymer is —CH
2
—CH
2
—.
Where melt index values are specified in the present application without giving measurement conditions, the melt index as defined in ASTM D-1238, Condition 190° C./2.16 kg (formerly known as “Condition (E)” and also known as I2) is meant. Melt index is inversely proportional to the molecular weight of the polymer. Thus, the higher the molecular weight, the lower the melt index, although the relationship is not linear.
The term “substantially linear” ethylene polymer or interpolymer as used herein means that, in addition to the short chain branches attributable to intentionally added &agr;-olefin comonomer incorporation in interpolymers, the polymer backbone is substituted with an average of 0.01 to 3 long chain branches/1000 carbons, more preferably from 0.01 long chain branches/1000 carbons to 1 long chain branches/1000 carbons, and especially from 0.05 long chain branches/1000 carbons to 1 long chain branches/1000 carbons.
Long chain branching is defined herein as a chain length of at least 1 carbon less than the number of carbons in the longest intentionally added &agr;-olefin comonomer, whereas short chain branching is defined herein as a chain length of the same number of carbons in the branch formed from any inten
Bank David H.
Sehanobish Kalyan
Warakomski John M.
Wu Shaofu
Mullis Jeffrey
The Dow Chemical Company
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