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
1999-11-02
2002-02-12
Woodward, Ana (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...
C524S502000, C524S505000, C524S508000, C524S513000, C524S514000, C525S072000, C525S076000, C525S133000, C525S146000, C525S151000, C525S153000, C525S155000, C525S165000, C525S166000, C525S175000, C525S178000, C525S179000, C525S180000, C525S184000, C525S186000, C525S189000, C525S207000, C525S209000, C525S213000
Reexamination Certificate
active
06346571
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to thermoplastic compositions having improved properties and a process for preparing the compositions. Optionally, these blends may be dynamically vulcanized.
2. Description of Information Disclosures
In recent years, there has been a significant commercial interest in polymer blends which have a combination of both elastic and thermoplastic properties. These polymer blends have been given the generic designation of Thermoplastic Olefins (“TPO”). They exhibit some of the properties of a cured elastomer as well as the reprocessability of thermoplastic resins. The elastomeric characteristics may be enhanced if one component of the blend is a vulcanizable elastomer which is wholly or partially crosslinked.
U.S. Pat. No. 4,130,534 discloses elastoplastic compositions comprising a blend of a thermoplastic crystalline polyolefin resin and a rubber which may be butyl rubber, chlorobutyl rubber or bromobutyl rubber.
U.S. Pat. No. 4,172,859 discloses a thermoplastic composition containing a polyamide matrix resin and at least one polymer having a specified tensile modulus.
U.S. Pat. No. 4,174,358 discloses a thermoplastic composition containing a polyamide matrix resin and at least one polymer having a specified tensile modulus.
The earliest work in the curing of TPO compositions was by Gessler and Haslett; see U.S. Pat. No. 3,037,954. That patent teaches the concept of “dynamic curing” wherein a vulcanizable elastomer is dispersed into a resinous thermoplastic polymer and the elastomer cured while continuously mixing and shearing the polymer blend. The result is a micro-gel dispersion of cured rubber in an uncured matrix of resinous thermoplastic polymer. Gessler's U.S. Pat. No. 3,037,954 discloses compositions comprising polypropylene and a rubber wherein the rubber may be, butyl rubber, chlorinated butyl rubber, polybutadiene, polychloroprene and polyisobutene. Compositions of about 50 to 95 parts polypropylene and about 5 to 50 parts of rubber are disclosed.
U.S. Pat. No. 4,639,487 discloses a heat shrinkable thermoplastic composition of an ethylene copolymer resin with a dynamically vulcanized halogenated butyl rubber.
Dynamically vulcanized thermoplastic compositions comprising a polyamide and various types of elastomers are known. See, for example, U.S. Pat. No. 4,173,556; U.S. Pat. No. 4,197,379; U.S. Pat. No. 4,207,404; U.S. Pat. No. 4,297,453; U.S. Pat. No. 4,338,413; U.S. Pat. No. 4,348,502; and U.S. Pat. No. 4,419,499.
U.S. Pat. No. 4,287,324 discloses a dynamically vulcanized composition comprising a blend of a crystalline polyester and a cured epichlorohydrin.
U.S. Pat. No. 4,226,953 discloses a dynamically vulcanized composition comprising a blend of styrene-acrylonitrile resin and a nitrile rubber.
U.S. Pat. No. 4,350,794 discloses a polyamide molding and extrusion composition prepared by melt blending a polyamide resin and a polyamide reactive halogen functional elastomer.
There is still a need to improve the properties of uncured and of dynamically vulcanized alloys.
It has now been found that compositions comprising a thermoplastic engineering resin and a halogen-containing copolymer of an isoolefin and a para-alkylstyrene have improved properties, such as higher Vicat softening temperature, lower oil absorption, resistance to compression set, and retention of properties after heat aging. Moreover, these compositions may be stabilized to ultraviolet light exposure without adversely affecting their properties. The compositions may also comprise uncured or dynamically cured elastomers.
SUMMARY OF THE INVENTION
In accordance with one embodiment of the invention, there is provided a thermoplastic composition comprising a polymer blend of a thermoplastic engineering resin, and an elastomeric halogen-containing copolymer of a C
4
to C
7
isomonoolefin and a para-alkylstyrene.
In accordance with an other embodiment of the invention, there is provided a thermoplastic composition comprising a vulcanized polymer blend of a thermoplastic engineering resin, and an elastomeric halogen-containing copolymer of a C
4
to C
7
isomonoolefin and a para-alkylstyrene.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic composition of the present invention comprises a blend of a thermoplastic engineering resin, and an elastomeric halogen-containing copolymer of a C
4
to C
7
isomonoolefin and a para-alkylstyrene which may be an unvulcanized composition or which may be statically vulcanized or which may have been subjected to dynamic vulcanization.
The term “dynamic vulcanization” is used herein to connote a vulcanization process in which the engineering resin and a vulcanizable elastomer are vulcanized under conditions of high shear. As a result, the vulcanizable elastomer is simultaneously crosslinked and dispersed as fine particles of a “micro gel” within the engineering resin matrix.
Dynamic vulcanization is effected by mixing the ingredients at a temperature which is at or above the curing temperature of the elastomer in equipment such as roll mills, Banbury® mixers, continuous mixers, kneaders or mixing extruders, e.g., twin screw extruders. The unique characteristic of the dynamically cured compositions is that, notwithstanding the fact that the elastomer component may be fully cured, the compositions can be processed and reprocessed by conventional rubber processing techniques such as extrusion, injection molding, compression molding, etc. Scrap or flashing can be salvaged and reprocessed.
In the embodiment of the invention in which it is desired to obtain dynamically vulcanized alloys (DVA's) the alloys are generally prepared by blending together at least one engineering resin and at least one elastomer with curatives and fillers under conditions of dynamic vulcanization.
In preparing the preferred dynamically vulcanized composition of the present invention, at least a portion of one thermoplastic engineering resin is blended with the elastomeric halogen-containing copolymer.
The thermoplastic engineering resins suitable for practice of the present invention may be used singly or in combination and are resins containing nitrogen, oxygen, halogen, sulfur or other groups capable of interacting with an aromatic haloalkyl group. Suitable engineering resins include resins selected from the group consisting of polyamides, polycarbonates, polyesters, polysulfones, polylactones, polyacetals, acrylonitrile-butadiene-styrene resins (ABS), polyphenyleneoxide (PPO), polyphenylene sulfide (PPS), styrene-acrylonitrile resins (SAN), polyimides, styrene maleic anhydride (SMA), aromatic polyketones (PEEK, PEK, and PEKK) and mixtures thereof. Preferred thermoplastic engineering resins are polyamides. The more preferred polyamides are nylon 6 and nylon 11.
Suitable thermoplastic polyamides (nylons) comprise crystalline or resinous, high molecular weight solid polymers including copolymers and terpolymers having recurring amide units within the polymer chain. Polyamides may be prepared by polymerization of one or more epsilon lactams such as caprolactam, pyrrolidione, lauryllactam and aminoundecanoic lactam, or amino acid, or by condensation of dibasic acids and diamines. Both fiber-forming and molding grade nylons are suitable. Examples of such polyamides are polycaprolactam (nylon-6), polylauryllactam (nylon-12), polyhexamethyleneadipamide (nylon-6,6), polyhexamethyleneazelamide (nylon-6,9), polyhexamethylenesebacamide (nylon-6,10), polyhexamethyleneisophthalamide (nylon-6,IP) and the condensation product of 11-aminoundecanoic acid (nylon-11). Additional examples of satisfactory polyamides (especially those having a softening point below 275° C.) are described in Kirk-Othmer, Encyclopedia of Chemical Technology, v. 10, page 919, and Encyclopedia of Polymer Science and Technology, Vol. 10, pages 392-414. Commercially available thermoplastic polyamides may be advantageously used in the practice of this invention, with linear crystalline polyamides having a softening point or melting point between 160°-230° C
Dharmarajan Narayanaswami Raja
Hazelton Donald Ross
Powers Kenneth William
Puydak Robert Chester
Wang Hsien Chang
ExxonMobil Chemical Patents Inc.
Faulkner Kevin M.
Kurtzman Myron B.
Peebles Brent M.
Woodward Ana
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