Nylon modifiers having enhanced flow properties

Details Nylon modifiers having enhanced flow properties Nylon modifiers having enhanced flow properties

2000-03-22

2001-05-22

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...

C525S069000, C525S074000, C525S207000, C525S179000

Reexamination Certificate

active

06235840

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to modifiers for use in thermoplastic polyamide compositions that have improved ductility and toughness and to processes for preparing such compositions; specifically, the modifiers of the present invention have better flow and easier dispersibility than previously known materials during compounding with polyamides.
2. Description of Related Art
Thermoplastic polyamides are a class of materials that possess a good balance of properties, e.g., excellent mechanical characteristics, high heat resistance, and good durability, that make them useful as structural materials. On the other hand, they are known to be deficient in impact resistance, notch sensitivity, and moisture resistance. One route to improving impact resistance is by blending the polyamide with another polymer. Unfortunately, it has often been found that such blends provide their own set of problems, e.g., immiscibility between the polyamide and the modifying polymer, which can bring about poor adhesion between the two, leading to weak areas at their interface that result in mechanical failure.
It is difficult to obtain a good dispersion of a combination of a polar polymer, such as a polyamide, with a non-polar polymer, such as a polyolefin. It is known that the addition of a graft or block copolymer of similar chemical structure to the blend components can improve the quality of the dispersion. These copolymers, generally referred to as compatibilizers, are often added as a third component to the blend. Maleic anhydride grafted polypropylene has been suggested as a compatibilizer for polypropylene
ylon blends by Ide et al.,
J. Appl. Polym. Sci.,
18:963 (1974). The compatibilization of polyethylene/polyamide blends with maleic anhydride grafted polypropylene has been reported by Chen et al.,
Polym. Engng. Sci.,
28:69 (1988). These and similar blends have been studied and the results reported by Park et al.,
Eur. Polym. J.
26(2):131-136 (1990).
A compatibilizing agent is a material that, on a molecular scale, has particular regions that are compatible with each of the incompatible constituent polymers. Such compatibilizing agents typically surround one polymeric phase providing a chemical and/or physical bridge to the other polymeric phase. Insofar as portions of the compatibilizing agent are compatible with each of the constituent polymers, the bonding between the two incompatible polymeric phases is effectively enhanced through this intermediate compatibilizing phase. Such a system of incompatible polymers coupled by a compatibilizing agent results in a material that advantageously combines the more desirable properties of the constituent polymers.
A method of reclaiming mixed immiscible polymers by employing a compatibilizing agent has been described by Lindsey et al.
J. Appl. Polymer Sci.
26:1-8 (1981). The system studied was a high density polyethylene (HDPE) and is polystyrene (PS) and a styrene-ethylene-butene-1-styrene (SEBS) copolymer (a linear triblock copolymer) as the compatibilizing agent. These ternary blends exhibited a considerable improvement in the balance of mechanical properties over a binary blend of high density polyethylene and polystyrene.
U.K. Patent Number 998,439 discloses a thermoplastic composition comprising a mixture of 50 to 99 percent linear polyamide and 1 to 50 percent of olefin copolymer particles, the olefin copolymer containing from 0.1 to 10 mole percent of acid groups.
U.S. Pat. No. 3,668,274 teaches improved impact strength of polycarbonamides modified with (A) a first elastomer phase of copolymers or terpolymers and (B) a final rigid phase thermoplastic stage containing amine-reactive moieties, preferably carboxylic acid groups.
U.S. Pat. No. 3,845,163 discloses blends of 60 to 85 percent by weight polyamide and an acid-containing olefin polymer in which the acid is derived from an &agr;,&bgr;-ethylenically unsaturated carboxylic acid and in which at least 10 percent of the acid groups has been neutralized with metal ions.
U.S. Pat. Nos. 3,388,186 and 3,465,059 disclose polyamide compositions that possess high impact strength with some values in excess of 10 foot pounds per inch. The disclosed compositions are graft copolymers prepared from an ethylene containing polymer.
U.S. Pat. No. 4,174,358 discloses toughened multiphase thermoplastic compositions consisting essentially of one phase containing 60 to 99 percent by weight of a polyamide matrix resin of number average molecular weight of at least 5,000 and 1 to 40 percent by weight of at least one other phase containing particles of at least one polymer that is adhered to the polyamide and has a particle size in the range of 0.01 to 3.0 microns and a tensile modulus in the range of 1.0 to 20,000 psi, wherein the ratio of the tensile modulus of the polyamide matrix to the tensile modulus of polymer is greater than 10 to 1.
U.S. Pat. No. 4,427,828 and WO83/00492 disclose blends of thermoplastic polyamide with a modified block copolymer to increase the impact strength of the polyamide.
U.S. Pat. No. 4,647,509 discloses a multilayer thermoformable packaging material comprising a first layer of (a) a vinylidene chloride polymer, (b) an incompatible polymer, e.g., polyesters and nylons, and (c) a compatibilizing agent, and a second layer of (a) a blend of an olefin polymer, a styrenic polymer, and a compatibilizing polymer, and (b) scrap material produced from the first and second layers. The compatibilizing polymers for the second layer are preferably block copolymers of olefins and styrene, such as copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, etc.
U.S. Pat. No. 4,657,970 describes polymer compositions comprising at least one thermoplastic polymer including polyamides, thermoplastic polyesters, thermoplastic polyurethanes, vinyl alcohol polymers, etc., and at least one modified block copolymer of a monovinyl-substituted aromatic hydrocarbon polymer block A and at least one olefin compound polymer block B, to which has been grafted at least one molecular unit containing at least one member selected from a carboxylic acid group and groups derived therefrom. The modified copolymers and compositions are said to have excellent impact resistance, adhesion, paint adhesion, weatherability, resistance to aging, transparency, etc.
U.S. Pat. No. 4,795,782 describes a polymer blend—said to exhibit improved impact resistance—comprising a polyamide, a functionalized polyolefin, and a functionalized elastomer. The functionalized polyolefins are obtained by reacting a polyolefin with an unsaturated mono- or polycarboxylic acid or derivative thereof. Suitable unsaturated mono- or polycarboxylic acids include maleic anhydride, maleic acid, fumaric acid, etc. The functionalized elastomers described are generally functionalized selectively hydrogenated block copolymers of conjugated dienes and vinyl aromatic compounds. The block copolymers are functionalized by grafting the copolymers with a mono- or polycarboxylic acid compound, such as maleic anhydride, maleic acid, fumaric acid, etc. Other monomers that are utilized for introducing the functionality include vinyl monomers, such as acrylamide, acrylonitrile, monovinyl aromatic compounds (e.g., styrene), vinyl esters, vinyl ethers, etc.
U.S. Pat. No. 5,278,231 describes blended polymer compositions said to have improved impact resistance comprising:
(I) from about 1 percent to about 97 percent by weight of at least one alpha-olefin polymer;
(II) from about 1 percent to about 97 percent by weight of at least one polyamide;
(III) from about 1 percent to about 97 percent by weight of at least one polymer of a vinyl aromatic hydrocarbon;
(IV) an effective amount of a mixture of two or more compatibilizing agents selected from the group consisting of
(a) at least one selectively hydrogenated block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene;
(b) at least one selectively hydrogenated block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene to w

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