POLYAMIDE COMPOSITION RESISTANT TO FLUOROCARBON AND HYDROCARBON PERMEATION

Abstract: The present invention is a polyamide composition which is resistant to fluorocarbon and hydrocarbon permeation and at the same time has controllable flexibility. The composition of the present invention comprises from about 50 to 90 percent by weight of a polyamide, from about 5 to 40 percent by weight of a rubber phase that may be melt-processed at from about 425 to 625 DEG F (218 to 329 DEG C) without significant degradation, and from about 5 to 40 percent of a polar polyethylene. The composition can also have from about 0 to 15% by weight of a plasticizer and from about 0 to 10% by weight of a polyamide chain extender.

Description: POLYAMIDE COMPOSITION RESISTANT TO FLUOROCARBON AND HYDROCARBON PERMEATION BACKGROUND OF THE INVENTION This invention relates to polyamide compositions; and more particularly, to polyamide compositions which are resistant to fluorocarbon and hydrocarbon permeation. At the present time, it is Known to use nitrile rubber-based compositions to make fluorocarbon permeation resistant articles, such as hosing and tubing. Nitrile rubbers are butadiene acrylonitrile copolymers. They are flexible and known for gas permeation resistance and oil resistance. Babbit, The Vahderbilt Rubber Handbook. RT Vanderbilt (1978) discloses a typical nitrile rubber composition, useful to make hosing (at page 720). While such compositions may be useful to blend with polya ides and form fluorocarbon permeation resistant articles, the processing of such compositions presents certain limitations. A critical concern is that at the temperatures necessary to process polyamides, nitrile rubbers might decompose to form hydrogen cyanide and acryloni rile monomer. Both of these materials are undesirable. Therefore there is a eed in the art for a polyamide composition which is resistant to hydrocarbon and fluorocarbon permeation, which is controllable with respect to flexibility, and which can be processed at processing conditions typically used to process nylon, i.e., 425 to 625 β F (218 to 329 β C) , without emitti undesirable degradation compounds. SUMMARY OF THE INVENTION The present invention is a polyamide composition which is resistant to fluorocarbon and hydrocarbon permeation and at the same time has controllable flexibility. The polyamide composition of the invention contains a rubber phase to flexibilize, which is not in and of itself resistant to the permeation of fluorocarbons and hydrocarbons, but can be processed at the high processing temperatures of polyamides wh?ch are typically between, about 425° to 625°F(218 to 329"c). it h discovered"that selective polyethylenes functionalized with polar groups can be incorporated with this rubber phase to result in a fluorocarbon and hydrocarbon permeation resistant composition that also retains tensile-type physical properties while maintaining a lower flex modulus. Thus, the composition of the present invention comprises from about 50 to 90 percent by weight of a polyamide, from about 5 to 40 percent by weight of a rubber phase that ay be melt-processed at from about 425 to 625 β F (218 to 329*0) without significant degradation, and from about 5 to 40 percent of a polar polyethylene. The composition as indicated above can also have from about 0 to 151 by weight of a plasticizer and from about 0 to 10*. by weight of a polyamide chain extender. These last two ingredients can be used to further flexibilize the polyamide or balance and fine-tune flexibility and physical properties, without deterring from fluorocarbon and hydrocarbon resistance. The present invention also includes fluorocarbon and hydrocarbon permeation resistant articles made from the above-recited composition. Articles of particular interest are tube and hosing used as conduits for fluorocarbons commonly used as refrigerants for refrigerators and air conditioning systems. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a polyamide composition which comprises polyamide, a rubber phase, a polyethylene functionalized with polar groups and optionally a plasticizer and polyamide chain extender. The polyamide component of the composition of the invention is the predominant component. Preferred percent ranges by weight of this component are from about 50 to 90%. preferably about 60 to 90* and more preferably about 70 to 80* by weight of the total composition. Polyamides suitable for use herein include the long chain polymeric amides having recurring amide groups as part of the polymer backbone and preferably having a number average molecular weight, as measured by end group titration of about 15,000 to 40.000. The polyamides suitable for use herein can be produced by any conventional process known in the art. Non-limiting examples of such polyamides are: (a) those prepared by the polymerization of lactams, preferably epsilon-caprolactam (nylon 6); (b) those prepared by the condensation of a diamine with a dibasic acid, preferably the condensation of hexamethylene diamine with adipic acid (nylon 6,6). the condensation of hexamethylene diamine with sebacic acid (nylon 6.10) and polytetramethylene adipamide (nylon 4.6); and (c) those prepared by self-condensation of amino acids, preferably self-condensation of ll-aminodecanoic acid (nylon -li) ,- or random, block, or graft interpoly ers consisting of two or more of these polyamides. Preferred are those obtained by the polymerization of epsilon-caprolactam. The most preferred are copolymers of caprolactam and hexamethylene adipamide ^ N 6.66 ) - Polyamides such as nylon-6 or nylon 6,6 can contain a variety of terminal functionalities, including: (a) a carboxyl group attached to both ends of the polyamide chain; (b) a carboxyl group attached to one end and an amide group attached to - the other end of the polyamide chain (the "capped" end) (only polycaprolacta s) ; (c) an amino group attached to both ends of the polyamide chain; and (d) a carboxyl group attached to one end and one amine group attached to the other end of the polyamide chain (polycaprolactams. ) The polycaprolactam if unwashed can contain up to 15%, and typically from 0.5 to 12* by weight based on the weight of polycaprolactam. of a caprolactam monomer or water extractable caprolactam oligomers. 5 In a N- , c composition, the caprolactam amount corresponds to the amount of caprolactam in the No,,b.b, polymer. The composition contains a rubber phase which can be polar or nonpolar. and is capable of being melt processed at from about 425 to 625°F (218 to 329 c), without significant degradation. It is preferred that nσn-nitrile type rubbers be used. As used herein, a polar rubber phase means a low modulus flexible polymer with a glass transition below 0°C, preferably 5 below -25°C and containing polar monomers of acids, esters, ethers, aldehydes, ketones, alcohols and halides. The polar rubber may also contain an anhydride for reaction with the nylon. In some cases the rubber phase may be 0 considered to be nonpolar. By this is meant a low modulus flexible polymer with a glass transition below 0°C. and preferably below -25°C, and containing non-polar monomers such as ethylene and alpha-oiefins such as propylene, butylene and the like. The 5 non-polar rubber may also contain an anhydride group for reaction with the nylon. It should be appreciated, however, that when the rubber phase is nonpolar, the third component of the compositions of the invention (as described in detail below) should be adjusted accordingly, to attain the desired fluorocarbon or hydrocarbon resistance. Preferred in the context of nonpolar rubbers are copolymers of ethylene and other than ethylene monomers, such as alpha-olefins, having a reactive moiety graf-ted to the ethylene copolymer. The ethylene and alpha-oiefin is preferably a copolymer of ethylene and an alpha-olefiή selected from at least one C ~C Q , and pref erably C -C alpha-oiefin Propylene is a 3 6 pref erred monomer selected as the C -C alpha-oiefin j 8 in the copolymer. Other C 3 -C fi aipha-olefins,. such as 1-butene. 1-pentene. and 1-hexene can be used in place of or in addition to propylene in the copolymers. Ethylene/propylene diene polymers are also preferred for use herein. In other preferred embodiments, either polar or nonpolar rubbers may be functionalized. For example, a carboxyl or carboxylate functionality can be supplied by reacting the ethylene/C,-C £ alpha-oiefin copolymer with an unsaturated reactive graft moiety taken from the class consisting of alpha,beta- sthylenically unsaturated dicarboxylic acids having from 4 to 8 carbon atoms, or derivatives thereof. Such derivatives include anhydrides of the dicarboxylic acids. Illustrative of such acids and derivatives are maleic acid, maleic anhydride, maleic acid rnanoethyl ester, metal salts of maleic acid monoethyl ester, fumaric acid, fumaric acid monoethyl ester, itaconic acid, vinyl benzoic acid, vinyl phthalic acid, metal salts of fumaric acid monoethyl ester, monoesters of maleic or fumaric acid or itaconic acids where the alcohol is methyl, propyl, isopropyl. butyl, isobutyl. hexyl, cyclohexyl, octyl, 2-ethyl hexyl. decyl. stearyl. methoxy ethyl, ethoxy 48 —6— ethyl, hydroxy or ethyl, and the like. The reactive moiety can be grafted to the ethylene copolymer by any well-known grafting process. A useful reactive copolymer of ethylene and alpha-oiefin contains from 30 to 60 and preferably 40 to 45 weight percent of the alpha-oiefinbased on the ethylene. The copolymer also contains from 0.1 to 9%, and preferably 0.1 to 4 percent, and more preferably 0.3 to 2.0 percent by weight of the grafting moiety. The graft copolymer has a number average molecular weight of from 2,000 to 100,000, preferably.2.000 to 65.000, more preferably 5.000 to 35,000. and most preferably 5.000 to 20.000. Typical values of reduced solution viscosity (RSV) are from 0.5 to 3.5. A RSV of 2.8 corresponds to a number average molecular weight of about 80,000, an RSV of 2.0 corresponds to 35.000. and RSV of 1.0 corresponds to a number average molecular weight of 12,000. RSV is measured on a 0.1* solution in xylene at ilo°c. A good guideline to the selection of a rubbery phase component can be made by referring to that rubber's solubility parameter. A very soluble material will have a relatively high solubility parameter, and could be considered .polar in nature. The reverse would be true for a relatively nonpolar material. The solubility parameter in its use in permeation resistance is reviewed in U.S. Patent No. 4.261.473.. The solubility parameter, as used in that patent and for use in the present invention, is defined as the square root of the cohesion energy density (calories per cubic centimeter. CAL/cc) and is reviewed in Brandrup et al.. Polymer Handbook, Chapter 4. published by John Wiley & Sons. Inc. (1967). The solubility parameter of typical fluorocarbons is about 5.5. The solubility parameter of various materials is summarized in the following Table 1 for ease of reference: 48 -7 - TABLE 1 Solubility Parameter (cal/cc) fluorocarbon 5.5 polyethylene 8.0 polypropylene 7.9 EPR' Nitrile Rubber (B/AN) 80/20 8.7 70/30 9.4 60/40 10.5 0/100 12.8 polyvinyl acetate 9, polyvinyl alcohol 12, polylauryllactam (N.- 9. polyundercanamide (N ) 9. polycaprolactam (No,) 12. polyhexanethylene-sebacamide(N ) 12. polyhexamethylene adipamide(N ) 13. . 6.6 caprolactam/hexamethylene dxammonium 12.8 adipate copolymer N 6.66 n-ethyl o.p-toluenesul onamide 11.9 Thus, one of skill in the art will appreciate that if a nonpolar rubber is chosen as the rubbery phase component, it is preferred to use about 0 to 40*. and preferably from 10 to 30* and more preferably about 5 to 20* of a nonpolar rubber having a solubility parameter of less than about 9. Such rubbers have been found to further flexibilize the polyamide composition without substantially affecting tensile properties of the polymer. As indicated above, these nonpolar polymers can include polymers and copolymers having the same monomeric units as the polar polymers described above so long as the total ' -8- solubility parameter of the polymer is less than about 9.0. While these nonpolar rubbers need not contain groups that react with the end groups of the polyamide, it is preferred that they contain a small amount of reactive groups so as to form a network graft structure wherein the end groups of the polyamide are bonded to the reactive groups on the nonpolar rubber. The present inventors do not wish to be bound by theory; however, it is believed that this network structure is one of the reasons that the use of such materials helps to maintain physical properties while providing a lower flexural modulus. Particularly preferred for purposes of the rubbery phase of the compositions of the present invention are ethylene polymers such as ethylene ethyl acrylates, ethylene vinyl acetates and ethylene vinyl alcohols, and ethylene copolymers, such as ethylene/propylene copolymers. ethylene/propylene/diene copolymers. ethylene/butylene copolymers; and the like. The present inventors have also discovered that the addition of a functionalized polyethylene can be incorporated into the composition of the present invention to impart hydrocarbon resistance without detracting from the mechanical properties of the composition as a whole. Thus, the present composition also includes from about 5 to 40*, and preferably from about 10 to 35* of a polyethylene having functional groups. Said polyethylene preferably has a solubility parameter equal to or greater than about 9.0, and said polyethylene is capable- e-f being melt- processed at from about 425 to 625°F (218 to 329°C) without significant degradation. The polyethylene of the present invention is preferably an ethylene-based copolymer having sufficient polar groups along the backbone or grafted or otherwise attached thereto so that the solubility parameter of the total copolymer is preferably greater than about 9.0. The polar moiety may or may not be reactive with the end groups such as acid or a ine groups of the polyamide. Preferred polyethylenes for purposes of the present invention are those composed of ethylene monomeric units and polar monomeric units, such as anhydrides, acid groups and salts thereof, ester groups, aldehydes, ketones, ethers, hydroxyl groups, halogen groups, salts, and the like. Particularly preferred are salts of metals, such as salts of zinc, sodium., potassium, calcium, copper, lead and the like; esters, alcohol, acids, and the like. A good description of ionomers may be found in U.S. Patent No. 4,404.325. Ionomers having relatively low molecular weight, for example, a molecular weight of about 1500-3500. may also be useful. The composition may also contain a plasticizer that is suitable for plasticizing the polyamide component of the composition. The flexibility of the overall composition of the invention can be improved to an even greater extent with the addition of such a plasticizer. Preferred amounts range from about 2 to 20* by weight of a plasticizer. particularly preferred being about 5* to about 20*. Such plasticizers may vary widely and include but are not limited to lactams such as caprolactams and lauryl lacta . sulfona ides such as o.p-toluene sulfonamide. n-ethyl o.p-toluene sulfonamide, n-ethyl o.p-toluene sulfonamide, and n-butyl benzenesulfonamide. Other plasticizers include those selected from the group consisting of phthalate plasticizers. adipate plasticizers, phosphate plasticizers, glycolate plasticizers as well as the indicated sulfonamide plasticizers, tri ellitate plasticizers and polymeric-type permanent plasticizers. Optionally, it has been found that if large amounts of a plasticizer are used to attain greater flexibility in the overall composition, it may also be desirable to add a fifth component, a polyamide chain extender to attain a higher molecular weight species with a melt index suitable for extrusion type products. A higher molecular weight species will also retain greater levels of plasticizer without exuding them from the composition. By polyamide chain extender is meant a compound which can react with both the amine and acid to form amide links to increase molecular weight. For example. U.S. Patents Nos. 4.433.116, 4.417,031 and 4.417.032 describe suitable chain extenders. Suitable amounts range from about 0 to 10* by weight, preferably 0 to 5% and most preferably about 0.1 to about 3*. The composition can contain other polar materials such as polyvinylacetates, inorganic salts, and the like to increase resistance to fluorocarbon or hydrocarbon premeation. The compositions of the invention may also contain one or more conventional additives which do not materially affect the impact properties of the composition, such as stabilizers and inhibitors of oxidative. thermal, and ultraviolet light degradation, lubricants and mold release agents. colorants, including dyes and pigments, flame-retardants. fibrous and particulate fillers and reinforcements, nucleators, and the like. These additives are commonly added during the mixing step. Representative oxidative and thermal stabilizers which may be present in blends of the present invention include Group I metal halides, e.g.. sodium, potassium, lithium; cuprous halides, e.g., chloride, bromide, iodide; hindered phenols, hydroquinones. aromatic amines, and varieties of 8 - 11- substituted members of those groups and combinations thereof. Representative ultraviolet light stabilizers, include various substituted resorcinols, salicylates. benzotriazoles, benzophenones, and the like. Representative lubricants and mold release agents include stearic acid, stearyl alcohol, and stearamides. Representative organic dyes include nigrosine, while representative pigments, include titanium dioxide, cadmium sulfide, cadmium selenide, phthalocyanines. ultramarine blue, carbon black, and the like. Representative flame-retardants include organic halogenated compounds such as decabromodiphenyl ether and the like. The compositions of this invention can be prepared by melt blending a polyamide and at least one polymer into a uniform mixture in a single or twin screw extruder or other melt-compounding equipment. The compositions can be made into a wide range of useful articles by conventional molding methods employed in the fabrication of thermoplastic articles, i.e., as molded parts, extruded shapes, e.g.. tubing, films, sheets, fibers, sheets, fibers and oriented fibers, laminates and wire coating. "Molding" means forming an article by deforming the blend in the heated plastic state. The composition of the present invention is particularly, useful for extruded articles including tube and hosing to transport fluorocarbon fluids. The compositions are useful in making a variety of these types of tubing and hose as well as extruded tube and hose, pipe made of nylon, coextrusions of nylon with other polymeric materials, and coatings. EXAMPLES Several examples are set forth below to illustrate the nature of the invention and the manner of carrying it out. However, the invention should not be considered as being limited to the details thereof. All parts are perσents by weight unless otherwise indicated. Raw materials employed are as follows: Raw Materials Employed XPN - 1576 Nylon 6/66 (85/15) also ' referred to as €-Caproamide/ hexamethylene diamine adipate (85/15) containing approximate 7 to 8% caprolactam. MP Nylon 6 containing 9 to 11* caprolactam unextracted. EPM-g-MA Ethylene propylene rubber with 0.45* maleic anhydride grafted to it. The ethylene content is 45*. E/EA/MA Ethylene/ethyl acrylate (66/33) copolymer containing 1* maleic anhydride. ΞAA Ethylene/acrylic acid copolymer (93.5/6.5 from Dow Chemical Co.) S-9721 A zinc ionomer from DuFont. namely Surlyή 9721 chemically named ethylehe/methacrylic acid/zinc methacrylate (90/4/6) terpolymer. OPTSA ortho, para-toluene sulfonamide. a nylon plasticizer. U.C.BK Universal carbon black dispersion as 40* black on 60* ethylene vinyl acetate carrier. EVOH An ethylene vinyl alcohol copolymer. specially ethylene/vinyl alcohol/vinyl acetate (80/19/1) terpolymer. 8 The compositions in. the following Examples were generally prepared by first dry blending the materials, melt-extruding at about 500°F (260 c c) on a l" (2.54cm) single screw, extruder, using a conventional screw with an L/D of 25:1 and equipped with a Maddock mixing head. Extrudate strands were capidly passed through a water bath. The strands were passed through a pelletizing machine, and the pellets were collected. Test specimens were molded at a temperature slightly above the polyamide melting point.. The mold temperature was maintained at about 160-180*F (71-82 β C) . The molding cycle was 10 to 30 seconds forward ram, and 10 to 25 seconds on hold. The melt index was determined according to ASTM D-1238 Condition Q. The impact values were tested according to ASTM D=256 notched Izod using 1/8" (,32cm) or 1/4" (.64cm) test specimens as indicated. The tensile and elongation were tested according to ASTM D-638. and the flexural modulus was tested according to ASTM D-790. In the Examples, the following materials were used. The polyamide was nylon 6/66 copolymer which is a copolymer containing 92 mole percent of caprolactam and 8 mole percent of .hexamethylene adipamide. This copolymer was unwashed and contained from 7 to 9 percent of caprolactam monomer. The copolymer had a formic acid viscosity of 70. The formic acid viscosity is measured using 5.5 grams of nylon dissolved in 50 ml. of formic acid, 90* concentrated. Fluorocarbon permeation testing was performed according to the Springborn Testing Institute procedure. In general, the test procedure entailed obtaining tare weight of equipment assembly (this included a cell, pressure cap, test specimen, screen); clamping the test specimen, cooling assembly to below O c C, charging 60 grams of dichlorodi- fluoro ethane (Refrigerant 12j. sealing the charged cell with pressure cap, conditioning for 2 hours in a 100°C oven, cooling to ambient and obtaining initial weight (co 0.01 gram). The specimens were then exposed for 3 days at 100°C. cooled, weighed. Weight checks were repeated. Weight losses were reported between successive data times. EXAMPLES 1-6 Example 1-6 illustrate compositions of the present invention based on nylon 6/66 copolymers described above. These examples illustrate various combinations of a rubber phase, a polar ethylene copolymer and a plasticizer. The rubber phase consisted of an ethylene propylene copolymer having a maleic anhydride grafted thereto. The ethylene propylene maleic anhydride graft (EPMA) contained 45* ethylene. 55% propylene. and 0.45* maleic anhydride grafted thereto. It had a reduced solution viscosity of 1.6. The reduced solution viscosity was measured in a 1% solution in xylene at 110°C. The polar polyethylene was suriyn 9721 ionomer sold by DuPont. This material is indicated to be an ethylene methacrylic acid copolymer containing about 10% methacrylic acid which is 60* neutralized with zinc. This material has a melt index of 1.0. The plasticizer was Santicizer 9 which is o.p-toluene sulfonamide previously sold by Monsanto Corporation and described in their bulletin entitled "Plasticizers and Resin Modifiers"-IC/PL-361. EXAMPLE 1 Example 1 illustrates a composition of the present invention. It is based on a nylon 6.66 copolymer having 85 mole percent of caprolactam and N-ethyl o.p-toluene sulfonamide. and 15 mole percent of hexamethylene adipamide. The copolymer is unwashed and contains from 7 to 9 percent of caprolactam monomer. The composition further contains an ethylene propylene copolymer having maleic anhydride grafted thereto (hereinafter ETMA) . The EPMA contains a 45 ' o 55 wt. percent ratio ot ethylene to propylene. There is 0.66% by weight maleic anhydride grafted to the ethylene propylene copolymer. This copolymer has a reduced solution viscosity of 1.5 weight estimated as 10.000 to 12.000. The reduced solution viscosity is measured using a 0.1 percent solution in xylene at llo°C. The EPMA is the nonpolar rubber having insufficient maleic anhydride to have a solubility parameter of greater than 9.0. The solubility parameter of the EPMA is estimated to be approximately 8.0. The composition additionally contains an ethylene acrylic acid copolymer. The ethylene acrylic acid copolymer (hereinafter EAA) was commercially available from Dow Chemical as Dow EAA resin 455. It is described as having a melt index of 5.5 grams per 10 minutes and an acrylic acid content of 6.5 percent and an ethylene content of 93.5% with percents by weight. The physical properties of the composition are summarized in Table 1 below: TABLE 1 Co p 1 Comp 2 Comp 3 Ex 1 60 50 60 40 50 30 10 Nil Nil Nil 49K (338) 2900 (20) 40 5650 (39) 290 The melt flow ratio was measured according to ASTM test number D-1238. All compositions had nil melt flow under this test. A review of the Comparative I and II and Example 1 shows that the substitution of 10* of the polar EAA rubber resulted in the maintenance of physical properties when compared to Comparative II. The flexural modulus was somewhat higher than when using a corresponding equivalent amount of nonpolar rubber. However, when considering Comparative I. the flexural modulus was still significantly lower. The composition of Example 3, with 50% level of nylon and reactive rubber respectively, shows that excessive rubber to flexible can deteriorate physical properties. EXAMPLES 2-5 Examples 2-5 illustrate compositions containing varying amounts of the nylon 6/66. EPMA and EAA. of the type used in Example 1. The compositions and physical property results are summarized in Table 3 below : Ex 4 Ex 5 XPN-1576 50 50 EPM-g-MA 20 10 EAA 30 40 FL.MOD . PSI 55K 70K (MPa) (379) (483 ) FL . STR. , PSI 2000 2400 (MPa) (14) (17) YIELD ST. PSI 2560 2960 (MPa) (18) (20) YIELD EL. , % 30 30 U.T.ST . , PSI 3960 3500 (MPa) (27) (24) U .E . . . % 270 150 A review of Table 3 indicates that the amounts of polar polyethylene and rubber phase can be widely varied while maintaining satisfactory tensile properties and demonstrating relatively low flexural modulus. Reference is made to the comparatives in Table 2 which indicate that when only the rubber is used at a 50% level, flexural modulus is reduced substantially. However, physical properties also deteriorate. A review of Examples 2 through 4 show that a 50% level of the combination of polar polyethylene and rubber phase, the flexural modulus is still relatively low, although not as low as when using only the nonpolar rubber, and still enjoys the benefits achieved with varying amounts of the polar polyethylene. More importantly, a review of the physical properties of each of the Examples 2 through 5 indicate a higher tensile strength then when only the rubber phase is used. Therefore, the combination of a polar polyethylene and rubber phase enables the flexural modulus to be decreased while maintaining a higher tensile strength then is possible when no polar polyethylene is used, and at the same time having a lower flexural modulus similar to that achieved when only the polar polyethylene is used. '" Table 3 shows that flexible fluorocarbon and hydrocarbon resistant compositions can be produced by incorporating an ionomer or an ionic copolymer (S9721). This salt-containing copolymer can be expected to product a very high level of permeation resistance. What is also shown, is that flexibility can be maintained by the inclusion of the OPTSA (o.p-toluene sulfonamide) plasticizer. EXAMPLES 12 - 17 Examples 12 - 17 include embodiments of the present invention containing only a polar rubber, with and without a nylon plasticizer. The polymer used is a terpolymer of ethylene. ethylacrylate and maleic anhydride in a mole ratio of 66:33:1. It has a reduced viscosity of 1.4 and an estimated solubility parameter of 8.4. The compositions evaluated also contain a mixture of o.p-toluene sulfonamides (OPTSA) as described above. Certain of the compositions also contain universal carbon black which is an ethylene vinyl acetate copolymer containing 40% carbon black. The compositions and physical properties are summarized on Table 4 below: TABLE 4 Ex 12 The above examples illustrate that flexible compositions with excellent mechanical properties can also be achieved with a semi-polar rubber to contribute to hydrocarbon and fluorocarbon resistance. It should be noted that relatively good flexibility is achieved. The compositions evaluated in Table 5 illustrate polyamide compositions containing polar rubber of the present invention. The compositions also include varying amounts of OPTSA plasticizer and an evaluation of the use of universal carbon black master batch. The examples also illustrate that flexible highly polar blends can readily be pigmented without deterring from properties. For example, highly polar flexible compound as described in Examples 12 through 17. demonstrate very desirable mechanical properties, • plus measured fluorocarbon resistance. Table 5 below describes heat stabilized compounds with an excellent combination of flunroαarbon permeation resistance and good mechanical properties. -21- TABLE 5 EX. 18 10 15 20 25 30 35 TABLE 5 (Continued ) 19 20 21 55 60 20 15 25 15 10 97K 30K (669) (207) 1600 (11) 3370 3255 (23) (22) 5 5 6430 7380 (44) (51) 290 360 The above examples (19 and 20) show that in identical ormulations, replacement of the polar ethylene acrylic acid with a highly polar salt ionomer (high solubility parameter), results in a noticeable resistance to fluorocarbon permeation. If part of the ionomer is replaced with plasticizer (Ex.21), flexibility is increased, but at a slight sacrifice in resistance to fluorocarbons. TABLE 6 FLUOROCARBON RESISTANT EXTRUSION GRADES FLUOROCARBON RESIST: (SPRINGBORN) 39A TESTED 48A TESTED 0.31 G. LOSS 0.21g. loss in 7 days AFTER 19 DAYS 0.35g. loss in 14 days 0.44g. loss in 21 days. The above examples illustrate that a high level of fluorocarbon resistance can be achieved with a non-polar rubber like EPM-g-MA, by the use of lower modulus Nylon 6/66 with increased ionomer content. TABLE 7 FLEXIBLE FLUOROCARBON AND HYDROCARBON RESISTANT COMPOUNDS WITH LOW LEVELS OF NON-POLAR RUBBERS MFR 0.35 0.41 0.91 1.70 This table shows that highly polar compounds can still be produced but further lowering the non-polar rubber by replacing with an ionomer'. With as little as 8 wt%. the flex modulus is below 100K si ( 690 MPa ) . The following table reports-permeation data, as measured by hexane. of the various components used in the compositions of the present invention. Another useful guide to the development of flexible polyamide compositions is the measurement of permeability of the individual polymer components, themselves, as shown in Table 8. TABLE 8 RAW MATERIAL PERMEATION DATA PERMEABILITY (HEXANE) 2 -5 SAMPLE DESCRIPTION GMS - CM/CM /HRX10 AVER. Poly Latador 8040 E/EA/MA 154.0 147.0 158.0 153 (66/32/2) Prima E/P/KA 186.0 202.0 197.0 195 (45/55/0.5) Promar E/AA 2.6 2.6 2.7 2.6 (93.5/6.5) Surlyn 9721 E/MA/MA-Zn 2.1 2.1 2.2 2.1 (90/4/6) Dumilan 1595 E/VOH(80/20) 0.04 Pakto E/EA (82/18) 40.7 Nylon XPN-1576 6/66 (85/15) 0.03 TABLE 9 NOVEL FLUOROCARBON RESISTANT COMPOUNDS CONTAINING EVOH EX.28 EX.29 Ex.30 EX.31 EX.32 56 MFR 3.00 1.90 1.10 1/7 2.1 8 -26 - The fluorocarbon resistant advantage of using an EVOH was demonstrated with hexane permeation testing. These examples illustrate that EVOH can be incorporated to besto resistance in nylon flexible grades, while still maintaining low modulus. For a modulus Of 76K psi (524 MPa), only 8 wt% non-polar rubber was required ro flexibilize. TABLE 10 Ex.36. is that combinations of ionic polymers can be utilized to balance mechanical properties.

Claims: WHAT IS CLAIMED IS: 1. A composition comprising: from about 50 to 90 percent by weight of polyamide; from about 5 to 40 percent by weight of a functionalized rubber phase capable of being melt processed at from about 218 to 329°c wi.thout si.gni.fi.cant degradation and having a solubility parameter of less than about 9.0; and from about 5 to 40 percent by weight of a ■ polyethylene having a solubility parameter equal to or greater than about 9.0. 2. The composition of claim 1 also comprising from about 5 to 15 percent by weight of a plasticizer for the polyamide. 3. The composition of claim 2 also comprising from .about 1 to 10 percent by weight of a polyamide chain extender. 4. The composition of claim 1 wherein said polyamide component is present in a range from about 60 to about 90% by weight of the total composition. 5. The composition of claim 4 wherein said polyamide component is present in a range from about 70 to 80% by weight of the total composition. 6. The composition of claim 5 wherein said rubber is functionalized with a carboxyl or carboxylate functionality. 7. The composition of claim 5 wherein said rubber phase is selected from the group consisting of ethylene ethyl acrylates, ethylene vinyl acetates, ethylene vinyl alcohols, ethylene propylene copolymers, ethylene propylene diene terpolymers, and ethylene butylene copolymers. 8. The composition of claim 7 wherein said rubbery phase component is present in amounts from about 5 to 20% by total weight of the composition. 9. The composition of claim 8 wherein said polyethylene is formed from ethylene monomeric units and polar monomeric groups selected from the group consisting of anhydrides, acid groups and salts thereof, ester groups, hydroxyl groups, halogen groups, aldehydes. ketones, and ethers. 10. The composition of claim 9 further including about 5 to 20% by weight of a plasticizer suitable for plasticizing the polyamide component of the composition.

Inventors: MASON CHARLES DRISCOLL, SMITH WESLEY FOREST, MASON, CHARLES, DRISCOLL, SMITH, WESLEY, FOREST
Applicants: ALLIED SIGNAL INC, ALLIED-SIGNAL INC.
Application year: 1988
Main classification: C08L77
IPC codes: C08L77