FAST CYCLING BLENDED POLYMER MATERIAL COMPRISING NYLON-6

Abstract: A composition comprising a Nylon, a maleated ethylen-propylen copolymer and an ethylene-methacrylic acid copolymer exhibits excellent toughness characteristics and fast molding times.

Description: I FAST CYCLING BLENDED POLYMER MATERIAL COMPRISING • Nylon-6 DESCRIPTION 1. Technical Field of the Invention The invention relates to polymer materials used in the production of molded articles; more particularly to molding materials comprising Nylon and other constituents which exhibit fast mold cycling time, and good toughness characteristics. Additionally, the molding material may comprise further constituents including styrene, maleic anhydride and other Nylons. 2. Background of the Invention Engineered materials enjoy widespread popularity for the production of formed articles. Typically, these materials comprise one or more polymers and other materials which exhibit specific properties, i.e., toughness, flexibility, chemical resistance, long-term stability, dielectric strength, etc. Frequently, materials which exhibit particular features such as those listed are used as constituents in formulations of so-called "polymer blends" which comprise a polymer and one or more constituent materials, such as an additional polymer or a non-polymeric material. Frequently, the purpose of the addition of such non-polymeric materials is to enhance the properties of the polymers, by acting as a "compatibilizer" and thus improve the adhesive properties of a polymer with a second "incompatible" polymer, or to impart other specific properties, such as increased toughness, elevated melting temperature, improved product clarity, abrasion resistance, chemical resistance, etc. Unfortunately, as is well known to the art, the formation of blended polymeric materials which feature all of the desirable characteristics of the constituents making up its formulation without simultaneously suffering some detrimental quality are rarely attained. Exemplary polymeric materials which exhibit satisfactory physical characteristics and good processability include the compositions described in U.S. Patent 4,174,358 for "Tough Thermoplastic Nylon Compositions" to Epstein, which discloses compositions which comprise a polya ide matrix and a second polymer which exhibits good impact toughness; U.S. Patent 4,879,324 for "Thermoplastic Molding Compositions Based On Polycarbonates, Polyesters and Polyamides" to Lausberg et.al. for thermoplastic molding compositions having favorable impact properties; and U.S. Patent 4,160,790 of Mason, et.al. for "High Impact Nylon Molding Compositions" which discloses compositions comprising nylon-6 and nylon-6,6 which feature improved toughness. Such materials provided in the prior art provide satisfactory solutions to many specific problems, problems which affect not only the considerations attendant upon the final product formed from a molding material, but also the problems peculiar to the production of articles from the material, including handling and processing. One important aspect of any production process is the time required to form each article, which is strongly dependent upon the characteristics of the particular composition being used. While materials known to the art provide satisfactory operating and performance characteristics suitable to many applications, the mere plurality of these available compositions demonstrates not only their great utility, but also the continuing need to provide new materials exhibiting yet further improved characteristics. Accordingly, it is an object of the invention to provide new compositions of polymeric materials comprising Nylon-6 which feature excellent physical characteristics, and superior processing features. SUMMARY OF THE INVENTION The instant invention is directed to new compositions of molding materials suitable for the production of molded articles; more particularly the invention relates to molding materials comprising a Nylon, a maleated polypropylene copolymer, and a modified ethylene-methacrylic acid copolymer. Additionally, the compositions may further include other constituents such as coloring agents, lubricants, plasticizers, mold releasing agents, nucleating agents, etc. Additionally, the use of co-modification agents is contemplated. Unlike the Nylon containing compositions known to the art, the compositions according to the present invention have been observed to exhibit excellent toughness as exhibited by Izod test values frequently in excess of 10, and relatively short mold retention time required for the production of formed articles therefrom. DESCSIPTIQN OF THE PREFERRED EMBODIMENTS In accordance with the present invention, the properties of unmodified Nylon-6 are improved by the addition of quantities of a maleated polypropylene copolymer, and quantities of an ethylene-methacrylic acid copolymer. As is well known to the art, maleic anhydride may be used as a reactant with the polypropylene copolymer to form a grafted copolymer exhibiting adhesive properties, said copolymer being the maleated copolymer comprised of the reaction product between the polypropylene copolymer and the maleic anhydride. Suitable maleated ethylene-propylene copolymer may be obtained from the USI Chemicals Co., of Rolling Meadows, Illinois under the trade name "PLEXAR", a U.S. registered trademark for a family of extrudable adhesive resins which are marketed for use as a tie layer between dissimilar polymer films. One especially suitable maleated polypropylene copolymer commercially available is marketed under the trademark "PLEXAR 420" from USI Chemicals Co. This particular PLEXAR is described as a modified, polypropylene based adhesive resin which provides excellent bonding between polyethylene or polypropylene, and Nylon or ethylene vinyl alcohol copolymers; typically exhibits a melt flow rate of 2.5 g/10 min. when tested according to test method ASTM D-1238, and exhibits a density of 0.918 g/cc tested according to test method ASTM D-1505. It is believed that this copolymer comprises isotactic polypropylene, ethylene-propylene copolymer and maleic anhydride. (Hereinafter, this composition will be interchangeably referred to as "ethylene-propylene copolymer.") The addition of the maleated ethylene-propylene copolymer primarily imparts the improvement of reducing the mold cycling time required in the production of articles utilizing materials according to the present invention, and contributes to imparting improved toughness, i.e. impact resistance to the otherwise unmodified Nylon-6. It is believed that the inclusion of the maleic anhydride is needed for the practice of the invention's teaching as it is hypothesized that the maleic anhydride provides a reaction site to which the Nylon may be attached. Other suitable reactive sites which find use in accordance with the present invention include glycidyl methacrylate, oxazolines, and related compounds, as listed in J.Appl.Polymer Science Vol.30, p.3325 et.seq. (1985) as well as oxazinones and related compounds as listed in J.Appl.Polymer Science Vol.32, p.4581 e .seq. (1986) , both of which are herein incorporated by reference. Suitable modified ethylene-methacrylic acid copolymers which may be used in the practice of the instant invention are those which are the reaction product between the ethylene-methacrylic .acid copolymer which is partially neutralized with alkali or alkaline earth ions, such as zinc, sodium, magnesium or lithium. The ethylene-methacrylic acid copolymer, may also be referred to as "E/MAA" . Suitable modified ethylene-methacrylic acid copolymers are presently commercially available from the E.I. DuPont de Nemours Company and are sold under the trademark "SURLYN" and are used as blending additives to polymers in order to improve the toughness of the polymer. Preferably, the modified ethylene-methacrylic acid copolymer selected from amongst the available SURLYNs should be those which have a relatively higher degree of neutralization. Generally, all SURLYNs will exhibit a beneficial effect, but the SURLYNs which have moderate and greater percentages of acid and percentages of neutralization are to be generally preferred in the practice of the invention. A preferred modified ethylene-methacrylic acid copolymer commercially available is "SURLYN 1801" which has been advantageously employed in the use of the present invention. The selection of the relative proportions of these constituent materials, which may also be termed the "initial polymer mixture" may be in any desired proportion in order to achieve the desired physical properties in any molded article to be ultimately produced from the initial polymer mixture. What "desired physical properties" is intended to mean is a set of satisfactory physical properties, i.e. satisfactory toughness and handling required for a particular application in conformity with the object of the present invention. It has been found that the objects of the present invention may be realized when initial polymer mixtures having respective weight percentages relative to the total weight of the composition, where Nylon-6 comprises between about 51 % to about 75 %, although percentages up to about 90% are contemplated as being useful, and wherein the maleated ethylene-propylene copolymer is present in excess of 0 % to about 25 %, and the modified ethylene-methacrylate copolymer is present in excess of 0 % to about 20 %. This convention of weight percentages relative to the total weight of a composition will be used hereinafter, and any percentages are to be understood as such, unless specifically noted to be otherwise. Preferably, the sum of the relative weight ratios of the maleated ethylene-propylene copolymer and the modified ethylene-methacrylate copolymers comprise in excess of about 16 % of the three constituents, although a sum of relative weight ratios as low as 10% is contemplated as being useful, and it has also been found that increasing the relative weight ratios has the desired effect of improving the characteristics of the material formed therefrom. The most advantageous range for the sum of these two constituents has been found to be between about 20 % to about 24 %. It has also been found that the ratio of the maleated ethylene-propylene copolymer to the modified ethylene-methacrylic acid copolymer allows for a significant range of variation without detracting from the improved toughness and handling properties of the product molding material. This ratio between the maleated ethylene-propylene copolymer and the modified ethylene-methacrylic acid copolymer can be adjusted so that the ratio varies between extremes of about 5 % and about 95 % maleated ethylene-propylene copolymer to ethylene-methacrylic acid copolymer which would be contemporaneously present in a ratio of between about 95% and about 5%. This variation in the ratios allows for the adjustment of the physical properties of the product material to have a degree of toughness in conformance with the particular need of a final molded article, while preserving the improved processability and handling of the material to be used for molding. Such a variation allows for the respective resultant properties, i.e., increased toughness imparted by increasing amounts of modified ethylene-methacrylic acid copolymer included as a constituent, which is balanced by a decrease in the residence time of the material in a mold used to produce an article which is attendant upon increasing amounts of maleated ethylene-propylene copolymer incorporated into a polymer material. As had been noted, additional constituents may be added to the composition which provide yet further improved characteristics to the material. These include such modifiers or other agents known to the art for imparting a particular effect upon a polymer and include plasticizers, viscosity stabilizers, mold release agents, fillers, nucleation agents, etc. which may be incorporated in any amount not found to have a detrimental effect upon the enjoyment of the instant invention. Further, amounts of different Nylons may be incorporated in the present invention. In a particular embodiment, a quantity of Nylon-6,6 in an amount which is to substitute up to about 10 % of the Nylon-6 constituent may be used. A suitable Nylon-6,6 should have amine end groups which will act to provide additional grafting sites for the maleated ethylene-propylene copolymer and the modified ethylene-methacrylic acid copolymer. It is preferred that the Nylon-6,6 comprise a preponderance of amine end groups, preferably in excess of about 75 %. It should be noted that the substitution of this relatively low amount of the Nylon-6,6 assures that Nylon-6 remains the major constituent used to form materials according to the instant invention. Examples of commercially available Nylon-6,6 having desirable numbers of amine terminal groups are marketed under the tradename "Polynil 50" and "Polynil 60" which are available from NILIT, Ltd. As an alternative to, or in addition to a quantity of Nylon-6,6 with a preponderance of amine end groups, it has also been found to be advantageous to provide Nylon-6 with a preponderance of amine end groups as a constitutent, as the amine end groups of the Nylon-6, also provide additional grafting sites for the maleated ethylene-propylene copolymer. Such a Nylon-6 should have an preponderance of amine end groups relative to the acid end groups, and is preferably in a proportion of amine to acid end groups of at least 70/30, with ratios of about 80/20 found to be advantageous, although a ratio of 70/30 is most preferred. Such a Nylon-6 is known to the art and is frequently available as an intermediate. A second constituent which may be added is a styrene maleic anhydride copolymer in an amount of up to about 1.0 % of the total mixture. The styrene maleic anhydride is a useful viscosity increasing additive which exhibits the desirous effect on the product polymer mixture of improved shape retention under high temperature conditions. A suitable styrene maleic anhydride which is commercially available is marketed under the designation "SMA 3000" by the Sartomer Company of West Chester, PA, U.S.A. This material is described as being a low molecular weight copolymer of styrene and maleic anhydride in anhydride and in partial ester form. Further, the compositions of the present invention may include conventional additives in small amounts, such as less than 5 % of a metal soap as a mold release agent or extrusion aid, and optionally a heat stabilizer such as a stabilizer based on copper. Further, plasticizers may be included, such as caprolactam monomers and water-extractable oligomers or sulfonamide plasticizers in amounts preferably not to exceed 15 % of the Nylon constituent. Further, other additives not specifically enumerated here may be incorporated in compositions according to the invention and are recognized as suitable for use as an additional constituent. It has been found that articles formed from compositions according to the invention feature exceptionally tough compositions and reduced "cycle time", i.e., retention time for the composition within a mold during the forming process as compared with compositions comprising Nylon-6 known to the art. The compositions of the present invention may be prepared by techniques well known to those skilled in the art including but not limited to the formation of a thermoplastic melt of the constituents, followed by a molding operation. Other methods for forming articles according to the compositions of the present invention may be utilized as desired. The following non-limiting examples are embodiments of the invention setting forth modes for carrying out the invention, and are not meant to be more limiting than the appendant claims. Examples: Examples 1-9 Compositions comprising Nylon-6, having both balanced and unbalanced end groups with an excess of amine end groups, "Polynil 50", a second Nylon-6 which is characterized to have unbalanced end groups, with an excess of amine to carboxyl end groups, preferably in a proportion of at least 70/30 and which is referred to in the Examples as "B-l", "SURLYN 1801", "PLEXAR 420", "SMA 3000" and "Acrawax C" were dry blended with the relative weight percentages to form compositions according to those outlined in Table 1. "SMA 3000" is a copolymer of styrene and maleic anhydride. "Acrawax C" is ethylene-bis-stearamide. TABLE 1 Sample : 1 2 3 4 5 6 7 8 9 Composition: Nylon-6 68.1 68.1 68.1 68.1 68.1 68.1 75.4 75.4 75.4 Polynil 50 7.3 7.3 7.3 B-l 7.3 7.3 7.3 SURLYN 1801 12 12 12 12 12 12 12 12 12 PLEXAR 420 12 12 12 12 12 12 12 12 12 SMA 3000 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Acrawax C 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 The respective constituents were dry mixed, after which they were melted and processed in a Leistritz twin screw extruder to form a blended composition. The temperature of the zones was typically as follows: zone 1; 210 deg.C, zone 2 through zone 5; 250 deg.C, zone 6, 230 deg.C. The exit die was maintained at a temperature of 255 deg.C. For these examples, all the constituents were introduced at a hopper located at the throat of the twin screws, and the feed rate was maintained at one of two rates, 25 or 55 lbs./hr. The composition was extruded through the exit die to form strands, which were subsequently quenched in a water bath, then pelletized. The pellets were dried, and then provided to an Arburg injection molding machine which was outfitted with a mold for the formation of standard sized 1/8-inch thick test bars used in accordance with ASTM test protocols for both impact and tensile tests. The pellets were melted, and pressure injected into the die under pressures of 1000 psi at barrel temperatures of 260 deg.C. The die was retained at a temperature of 150 deg.C. The die was retained at a temperature of 150 deg.F. Cycle time was tested on a Cincinnati Milacron molding machine, 150 ton, 6 oz. Barrel temperature profile was maintained at temperatures of 480 deg.F, 500 deg.F, 520 deg.F, as measured from the hopper then in a forward direction. The nozzle temperature was 530 deg.F, and the injection pressure was about 1700 psi. Mold temperature was maintained to be between about 150 to 160 deg.F. The article molded and used in the evaluation of the cycle time of the process utilizing the novel compositions of the instant invention were irregualarly shaped "dip stick" articles. For all Examples 1-9, the mold retention time of the compositions was 3 seconds, as is outlined in Tables 2 and 3 following, which also list the physical properties of the compositions according to Examples 1-9. It is to be noted that like numbered "Examples" correlate with correspondingly numbered results from physical property test data. TABLE 2 Sample: 1 2 3 4 5 Screw rpm: 220 220 150 220 220 Feed rate (lbs/hr): 25 55 25 25 55 Izod: 23.8 20.9 25.4 24.0 24.5 12.0 12.3 12.2 13.0 299.2 311.4 307.5 331.4 8.5 8.7 8.4 8.9 8.0 8.6 9.9 10.3 5 5 5 5 150 192 253 243 TABLE 3 Sample: Screw rpm: 150 220 220 220 Feed rate (lbs/hr): 25 25 55 25 Izod: 25.3 17.0 5.8 5.5 Flex Str (1000's): 11.9 12.0 11.6 13.2 Flex Modulus (1000's): 296.9 196.1 282.3 218.4 Tensile Yield (1000's): 8.5 8.7 8.3 9.4 Tensile Break (1000's): 10.0 6.5 6.3 7.2 Elongation Yield: 15 5 Elongation Break: 243 43 61 98 As may be ascertained from inspecting the physical property results outlined in Tables 2 and 3, the compositions exhibit high impact strength, in conjunction with short mold retention times of the compositions in the die of the injection molding process. (This mold retention time may also be termed "cycle time".) The materials also exhibited good overall flexural and tensile test results. Overall properties were improved when a small amount of the Nylon-6 was replaced fay Nylon-6,6 having predominant amine end group termination. The samples molded exhibited excellent mold release characteristics, Examples 10-23 Compositions comprising the Nylons of Examples 1-9, Polynil 50, SURLYN 1801, PLEXAR 420, SMA 3000 and Acrawax C having the compositions outlined in Tables 4A, 4B were prepared and subsequently molded in the manner generally outlined for Examples 1-9. As for the prior Examples 1-9, the compositions were fed at two different feed rates into.a Leistritz twin-screw extruder in order to determine if variations in the melt processing of the components effected modifications in the resultant physical properties, notably the Izod impact values and to a lesser extent, the tensile and flexural test values. Test bars were produced in a manner conforming to that used in Examples 1-9 including mold retention time of 3 seconds. A summary of the test results for Examples 10-23 are listed in Tables 5A, 5B and 5C below. TABLE 5A Sample: 10 11 12 13 14 Feed rate (lbs/hr): — — 25 55 25 Izod: 5.1 9.7 22.1 18.8 17.8 Flex Str. (1000's): 10.3 12.3 11.8 11.4 12.0 Flex Modulus (1000's): 266.7 337.0 297.1 284.5 299.9 Tensile Yield (1000's): 8.1 9.2 9.1 8.8 9.0 Tensile Break (1000's): 7.3 8.1 10.2 8.9 10.0 Elongation Yield: 5 5 5 5 5 Elongation Break: 150 109 284 242 285 TABLE 5B Sample: 15 16 17 18 19 Feed rate (lbs/hr): 55 25 55 25 55 Izod: 13.1 16.1 19.8 21.4 21.6 Flex Str. (1000's): 12.0 11.9 11.5 11.5 11.5 Flex Modulus (1000's): 296.8 299.7 283.8 290.1 273.3 Tensile Yield (1000's): 9.0 8.7 8.6 8.4 8.0 Tensile Break (1000's): 8.7 6.0 6.0 7.1 6.8 Elongation Yield: 5 Elongation Break: 238 136 129 100 112 TABLE 5C Sample: 20 21 22 23 Feed rate (lbs/hr): 25 55 25 55 Izod: 24.1 22.3 23.0 18.6 Flex Str. (1000's): 11.3 11.2 11.8 11.4 Flex Modulus (1000's): .285.7 269.9 286.3 281.6 Tensile Yield (1000's): 8.2 8.2 8.3 8.5 Tensile Break (1000's): 7.4 6.3 10.0 8.8 Elongation Yield: 5 Elongation Break: 167 202 233 293 The results from Tables 5A,5B and 5C illustrate that compositions having good impact properties, with Izod values frequently in excess of 10 may be formulated, while retaining short mold retention times. Examples 24-29 Compositions comprising the nylons used in Examples 1-9, Polynil 50, PLEXAR 420, SMA 3000 and Acrawax C were formulated to have the relative weight percentages outlined in Table 6. No SURLYN was utilized in the formulations. The constituents were mixed prior to processing in a manner corresponding to that used for Examples 1-9 including mold retention times of 3 seconds. TABLE 6 As the results in the Table 7 summarize, the respective compositions which lacked the modified ethylene-methacrylic acid copolymers, i.e. SURLYNs, showed satisfactory, although lower impact resistance as noted and as may be contrasted against other Examples which included amounts of SURLYN as a constituent, and which is evidenced in the resultant values for the Izod impact tests. TABLE 7 Sample: 24 25 26 27 28 29 Izod; 3.0 3.0 4.1 3.2 3.7 1.2 Flex Str. (1000's): 12.0 12.4 11.3 12.2 11.7 16.7 Flex Modulus (1000'S): 321.4 324.7 301.2 326.0 302.2 430.5 Tensile Yield (1000's): 8.5 8.5 8.2 8.5 8.3 11.6 Tensile Break (1000's): 6.2 6.7 6.3 6.6 δ .2 7.6 Elongation Yield: 5 5 Elongation Break: 82 88 85 30 80 117 Examples 30-40 Compositions comprising the nylons of Example 1-9, Polynil 50, SURLYN 1801, PLEXAR 420, SMA 3000 in weight proportions as outlined in Tables 8A and 8B were prepared in accordance with the procedure for extruding and molding generally outlined for Examples 1-9 including mold retention times of 3 seconds. •TABLE 8A Sample: 30 31 32 33 34 35 Composition: Nylon-6 Polynil 50 SURLYN 1801 PLEXAR 420 SMA 3000 Acrawax C TABLE 8B Sample: 36 37 38 39 40 Composition: a_aE-_-__ -__-_-a_ B_Ea Nylon-6 68.1 68.1 68.1 68.1 68.1 Polynil 50 7.3 7.3 7.3 7.3 10 SURLYN 1801 6 12 18 6 6 PLEXAR 420 18 12 6 18 21 SMA 3000 0.4 0.4 0.4 0.4 Acrawax C 0.2 0.2 0.2 0.2 0.2 The corresponding physical properties of each of Examples 30-40 are summarized on Tables 9A and 9B, TABLE 9A Sample: 30 31 32 33 34 35 Izod: 6.3 5.2 4.6 19.3 18.8 18.8 Flex Str. (1000'S): 11.9 11.9 12.0 11.6 11.5 11.5 Flex Modulus (1000's): 305.9 300.0 305.6 299.2 295.0 292.0 Tensi le Yield (1000's): 4.0 8.9 9.0 8.3 8.5 8.4 Tensile Break (1000's): 8.6 10.3 8.5 6.4 9.9 9.6 Elongation Yield: 5 5 5 5 5 5 Elongation Break: 199 296 241 216 253 282 TABLE 9B Sample: 36 37 38 39 40 Izod: 18.0 22.2 18.0 16.9 16.4 Flex Str. (1000's): 11.3 10.6 11.0 10.6 10.2 Flex Modulus (1000's): 292.3 269.4 282.6 267.7 262.4 Tensile Yield (1000's): 8.4 7.9 8.3 7.9 7.7 Tensile Break (1000's): 6.3 7.7 8.7 6.5 6.9 Elongation Yield: 5 Elongation Break: 252 284 220 229 190 As may be seen from the data tabularized on Tables 9A and 9B, the impact strength of compositions was found to be good when the total amount of the ethylene-methacrylic acid copolymer and the maleated ethylene-propylene copolymer is about 20% and shows further improvement when the total is about 24%. Further compositions comprising nylons of Examples 1-9 including the mold cycle time of 3 seconds, unless otherwise noted, Polynil 50, SURLYN 1801, PLEXAR 420 and Acrawax C were formulated. Additionally, the various compositions included further additives, including: amounts of magnesium oxide, and various grades of SMA's, specifically SMA .2000, SMA 2625 and SMA 3000. As noted above, these SMAs are materials, described as being a low molecular weight copolymer of styrene and maleic anhydride in anhydride and in partial ester form. Additionally, the amounts of Nylon-6,6 additives were alternated between "Polynil 50" and "Polynil 60". As noted above, "Polynil 50" is a Nylon-6,6 with predominantly amine end groups, while "Polynil 60" may be described as a Nylon-6,6 with a balanced ratio of amine end groups to acid end groups. The various compositions were prepared generally in accordance with the process utilized in the production of Examples 1-9. The compositions are listed in Tables 10A and 10B. TABLE 10A Sample: 41 42 43 44 45 46 47 48 49 Composition: Nylon-6 62.6 64.1 55.1 66.2 51.1 59.7 59.7 58.6 62.2 Polynil 50 10 10 15 Polynil 60 10 15 10 10 10 10 SURLYN 1801 6 2 6 2 6 6 6 6 2 PLEXAR 420 21 21 21 21 25 21 21 25 21 SMA 3000 0.4 0.4 0.8 SMA 2625 0.4 0.4 SMA 2000 0.8 0.4 0.8 0.8 MgO 2.5 2.5 2.5 2.5 2.5 TABLE 10B Sample: 50 51 52 53 54 55 56 57 58 Composition: Nylon-6 58.7 57.6 64.1 55.1 61.6 53.2 55.7 54.7 60.1 Polynil 50 15 10 15 10 Polynil 60 15 15 10 15 15 SURLYN 1801 2 2 2 6 2 6 6 2 2 PLEXAR 420 21 25 21 21 21 25 25 25 25 SMA 3000 0.8 0.4 0.4 0.8 0.4 SMA 2625 0.4 0.8 0.8 SMA 2000 0.4 MgO 2.5 2.5 2.5 2.5 2.5 2.5 Corresponding physical test date for Examples 41-58 are listed on Tables 11A,11B and 11C below. TABLE 11A Sample: 41 42 43 44 45 46 Cycle Time (sec. ) : Izod: 22.7 3.6 5.9 5.2 5.9 9.0 Flex Str. (1000's): 11.1 10.9 10.4 11.7 9.8 10.7 Flex Modulus (1000's): 281.9 271.8 268.1 300.6 248.4 273.8 Tensile Yield (1000's): 7.6 7.8 7.2 8.1 6.9 7.3 Tensile Break (1000's): 8.1 6.6 6.7 6.5 6.7 5.6 Elongation Yield: 5 3 Elongation Break: 163 33 41 26 58 64 TABLE 11B Sample: 47 48 49 50 51 52 Cycle Time (sec. ) : Izod: 8.0 13.9 5.7 4.8 14.7 4.3 Flex Str. (1000's): 10.6 10.5 10.8 11.2 10.7 11.2 Flex Modulus (1000's): 272.2 261.3 283.4 285.7 275.9 279.7 Tensile Yield (1000's): 7.2 7.6 7.3 7.7 7.6 7.9 Tensile Break (1000's): 7.7 7.0 6.6 5.4 7.0 6.6 Elongation Yield: 6 5 Elongation Break: 112 109 11 14 130 13 TABLE 11C Sample: 53 54 55 56 57 58 Cycle Time (sec. ) : Izod: 5.3 7.1 5.3 4.7 5.6 4.7 Flex Str. (1000's): 9.9 11.2 9.6 10.0 9.6 10.2 Flex Modulus (1000's) :249.4 279.8 256.2 246.9 256.7 252.0 Tensile Yield (1000's): 7.8 8.5 5.9 7.8 7.2 7.6 Tensile Break (1000's): 6.9 7.0 7.1 6.6 6.4 6.8 Elongation Yield: 5 Elongation Break: 23 14 17 16 19 27 From the resultant physical property data, it has been observed that the use of MgO exhibited a detrimental effect upon the impact properties of the compositions. While not wishing to be bound by any theory, it is hypothesized that the MgO reacts with the maleated ethylene-propylene copolymer and detrimentally affects the grafting with the Nylon polymer. Accordingly, compositions comprising MgO exhibit much poorer impact properties than compositions without MgO. The data also shows that the results obtained with the alternate usages of SMA 3000, SMA 2000 or SMA 2625 had little effect upon the resultant physical properties. Further, the total amount of modifiers used as constitutents to make up the compositions was seen to have an effect upon the resulting physical properties, particularly in the Izod impact test results Examples 59-66 Compositions including and omitting amounts of Nylon-6,6 ("Polynil 60") having the respective compositions listed in Table 12 were produced in accordance with the procedure followed for the production of Examples 1-9 as outlined above. The constituent "Stanyl KS 200" is a type 4,6 Nylon. TABLE 12 Example: 59 60 61 62 63 64 65 66 Composition: Nylon-6 75 74.4 67.5 66.96 67.5 66.96 7.44 7.44 Polynil 60 ~- 7.5 7.44 66.96 SURLYN 1801 4 4 4 4 4 4 4 4 PLEXAR 420 21 21 21 21 21 21 21 21 Stanyl KS 200 -- — — ~ 7.5 7.44 ~ 66.96 SMA 2625 ~ 0.6 0.6 0.6 0.6 0.6 Acrawax C 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 The resultant physical properties corresponding to Examples 59-66 are outlined in Tables 13A and 13B below. TABLE 13A Example: 59 60 61 62 Izod: 17.1 16.3 23.5 19.2 Flex Str. (1000's): 10.3 10.9 10.2 10.8 Flex Modulus (1000's): 254.0 264.2 245.4 267.6 Tensile Yield (1000's): 7.9 8.1 7.6 7.7 Tensile Break (1000's): 6.3 6.6 6.7 6.2 Elongation Yield: 5 5 Elongation Break: 178 96 160 149 TABLE 13B Example: 63 64 65 66 Izod: 17.6 21.5 5.7 6.7 Flex Str. (1000's): 10.5 10.5 11.4 11.2 Flex Modulus (1000's): 265.4 255.9 275.7 262.0 Tensile Yield (1000's): 8.4 7.7 8.3 8.9 Tensile Break (1000's): 6.2 6.0 7.1 8.6 Elongation Yield: 5 25 Elongation Break: 18 78 62 52 As may be ascertained from the resultant physical test data as summarized on Tables 13A and 13B, the use of compositions comprising Nylon-6, and which comprised no other species, or one other specie of Nylon could be formulated and still exhibit excellent strength retentive properties in molded articles while preserving short cycle times necessary for molding articles. Examples 67-72 Examples 67-72 comprise further compositions which include small amounts of Nylon-6,6 and Nylon-4,6 and which further omit the maleated propylene copolymer. These compositions were.produced in accordance with the procedure used in the production of Examples 1-9; particular constituents are tabularized in Table 14 below. The constituent "EEA 6169" is a copolymer of ethylene and ethyl acrylate which may be obtained from Union Carbide. TABLE 14 Example: 67 68 69 70 71 72 Composition: Nylon-6 59.4 56.9 56.9 56.9 Polynil 60 56.9 SURLYN 1801 20 20 20 18.5 18.5 18.5 Stanyl KS 200 56.9 SMA 2000 0.6 SMA 2625 0.6 0.6 0.6 0.6 0.6 EEA 6169 1.5 1.5 1.5 MgO 0.5 0.5 0.5 0.5 0.5 Corresponding physical properties for Examples 67-72 are presented in Table 15. TABLE 15 Sample: 67 68 69 70 71 72 Cycle Time (sec): 15 13 12 8 Izod: 12.2 17.6 29.7 28.9 3.1 4.3 11.4 11.0 11.8 273.8 252.7 273.7 7.8 8.1 9.3 10.7 7.4 8.8 5 20 30 201 61 86 As is indicated by the results on Table 15, good impact test results were achievable in compositions wherein the maleated propylene copolymer was omitted, however, the benefits of short mold residence times (i.e. cycle time) was diminished.

Claims: We claim: What is claimed is: 1. A polymeric composition comprising: at least one Nylon selected from: Nylon-6, Nylon-6,6, Nylon-4,6, Nylon-6/6,6; a maleated ethylene-propylene copolymer; an ethylene-methacrylic acid copolymer. 2. The polymeric composition according to claim 1 wherein at least one Nylon has a preponderance of amine end groups. 3. The polymeric composition according to claim 1 wherein the Nylon comprises between 51 weight % and 90 weight % of the composition. 4. The polymeric composition according to claim 1 wherein the Nylon comprises between 51 weight % and 75 weight % of the composition. 5. The polymeric composition according to claim 2 wherein the composition comprises Nylon-6,6 having an excess of amine terminal groups relative to the carboxylic acid end groups. 6. The polymeric composition according to claim 5 wherein the composition comprises Nylon-6,6 having a ratio of amine terminal groups relative to carboxylic acid end groups of at least 60/40. 7. The polymeric composition according to claim 1 wherein the composition comprises in excess of 0 weight % to 25 weight % maleated ethylene-propylene copolymer and, in excess of 0 weight % to 25 weight % modified ethylene-methacrylate copolymer. 8. The polymeric composition according to claim 1 which further includes a styrene-maleic anhydride copolymer. 9. The polymeric composition according to claim 1 which exhibits shorter molding times for forming articles therefrom than forming the same article from compositions consisting of Nylon-6 without the maleated ethylene-propylene copolymer and the ethylene-methacrylic acid copolymer of claim 1. 10. A molded article comprising the polymeric composition according to claim 1.

Inventors: ALPAUGH CHARLES W, GERVASI JAY A, SMITH WESLEY F, TULLER HAROLD W, ALPAUGH, CHARLES, W., GERVASI, JAY, A., SMITH, WESLEY, F., TULLER, HAROLD, W.
Applicants: ALLIED SIGNAL INC, ALLIED-SIGNAL INC.
Application year: 1991
Main classification: C08L77
IPC codes: C08L23, C08L25, C08L33, C08L51, C08L77, C08L91